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June 26, 2020
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https://www.sciencedaily.com/releases/2020/06/200626161205.htm
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International team of scientists warns of increasing threats posed by invasive species
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In a new study, scientists from around the world -- including a professor at the University of Rhode Island -- warn that the threats posed by invasive alien species are increasing. They say that urgent action is required to prevent, detect and control invaders at both local and global levels.
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Alien species are plants, animals and microbes that are introduced by people, accidentally or intentionally, into areas where they do not naturally occur. Many of them thrive, spreading widely with harmful effects on the environment, economy, or human health.The study, published in the journal According to Laura Meyerson, URI associate professor of natural resources science, the escalation in biological invasions is due to the increase in the number and variety of pathways along which species spread, and to the increasing volume of traffic associated with those pathways. For example, she notes the role played by emerging pathways such as the online trade in unusual pets and the transport of species across oceans on rafts of plastic.The researchers note that the scale of the problem is enormous. A 2017 analysis of global extinctions revealed that alien species contributed to 25 percent of plant extinctions and 33 percent of terrestrial and freshwater animal extinctions. Meanwhile, annual environmental losses caused by introduced species in the United States, United Kingdom, Australia, South Africa, India and Brazil have been calculated at more than $100 billion.The study also shows how drivers of global change, such as climate change, land-use change, and international trade, are exacerbating the impacts of biological invasions. Species transported through shipping can now thrive in new regions, for instance, owing to climate warming. And the permanent opening of the Arctic Ocean due to global warming is allowing marine species to move between the Atlantic and Pacific Oceans.The research paper is part of an initiative called World Scientists' Warning to Humanity: A Second Notice, which calls for urgent change in stewardship of the Earth and the life on it. The first notice, in 1992, was supported by 1,700 eminent scientists from around the globe who warned that humanity was on a collision course with the rest of the natural world. Twenty-five years later, a follow-up evaluation supported by 15,000 scientists declared that humanity had failed to make sufficient progress in dealing with the environmental challenges. Indeed, they found that most of these problems had worsened.The authors of the new paper stress that biological invasions can be managed and mitigated. They point to approaches that are working around the world and make specific recommendations for improved management. For example, the introduction of more stringent border controls, including X-ray machines and detector dogs, has led to a progressive decline in the rate of fungal plant pathogens entering New Zealand.Professor Petr Pyšek of the Czech Academy of Sciences and Charles University in Prague, lead author of the study, said: "As our knowledge about invasive alien species increases, the problems associated with biological invasions are becoming clearer. The threats posed by invasive alien species to our environment, our economies and our health are very serious, and getting worse. Policy makers and the public need to prioritize actions to stem invasions and their impacts."Professor David Richardson of the Centre for Invasion Biology at Stellenbosch University in South Africa, the other lead author, added: "Nations such as Australia and New Zealand have made biosecurity a national priority. South Africa has invested heavily in a massive national programme focussed on reducing the negative impacts of widespread invaders on ecosystem services, especially the delivery of water from catchments invaded by alien trees. But action is needed more widely at both national and international levels in order to tackle the challenges effectively."Meyerson, who contributed to the paper and is leading the chapter on trends in invasions for a report on invasive alien species for the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, said, "It has been so exciting to see developments in our knowledge and understanding of biological invasions in recent decades, achieved through truly inspiring global collaborations. It is so important that we continue to share our knowledge and engage with relevant stakeholders across sectors and borders."
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Geography
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June 26, 2020
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https://www.sciencedaily.com/releases/2020/06/200626141420.htm
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Geochemists solve mystery of Earth's vanishing crust
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Thank goodness for the Earth's crust: It is, after all, that solid, outermost layer of our planet that supports everything above it.
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But much of what happens below that layer remains a mystery, including the fate of sections of crust that vanish back into the Earth. Now, a team of geochemists based at the Florida State University-headquartered National High Magnetic Field Laboratory has uncovered key clues about where those rocks have been hiding.The researchers provided fresh evidence that, while most of the Earth's crust is relatively new, a small percentage is actually made up of ancient chunks that had sunk long ago back into the mantle then later resurfaced. They also found, based on the amount of that "recycled" crust, that the planet has been churning out crust consistently since its formation 4.5 billion years ago -- a picture that contradicts prevailing theories.Their research is published in the journal "Like salmon returning to their spawning grounds, some oceanic crust returns to its breeding ground, the volcanic ridges where fresh crust is born," said co-author Munir Humayun, a MagLab geochemist and professor at Florida State's Department of Earth, Ocean and Atmospheric Science (EOAS). "We used a new technique to show that this process is essentially a closed loop, and that recycled crust is distributed unevenly along ridges."In addition to Humayun, the research team included MagLab postdoctoral researcher Shuying Yang, lead author on the paper, and MagLab Geochemistry Group Director and EOAS Chair Vincent Salters.The Earth's oceanic crust is formed when mantle rock melts near fissures between tectonic plates along undersea volcanic ridges, yielding basalt. As new crust is made, it pushes the older crust away from the ridge toward continents, like a super slow conveyer belt. Eventually, it reaches areas called subduction zones, where it is forced under another plate and swallowed back into the Earth.Scientists have long theorized about what happens to subducted crust after being reabsorbed into the hot, high-pressure environment of the planet's mantle. It might sink deeper into the mantle and settle there, or rise back to the surface in plumes, or swirl through the mantle, like strands of chocolate through a yellow marble cake. Some of that "chocolate" might eventually rise up, re-melt at mid-ocean ridges, and form new rock for yet another millions-year-long tour of duty on the sea floor.This new evidence supports the "marble cake" theory.Scientists had already seen clues supporting the theory. Some basalts collected from mid-ocean ridges, called enriched basalts, have a higher percentage of certain elements that tend to seep from the mantle into the melt from which basalt is formed; others, called depleted basalts, had much lower levels.To shed more light on the mystery of the disappearing crust, the team chemically analyzed 500 samples of basalt collected from 30 regions of ocean ridges. Some were enriched, some were depleted and some were in between.Early on, the team discovered that the relative proportions of germanium and silicon were lower in melts of recycled crust than in the "virgin" basalt emerging from melted mantle rock. So they developed a new technique that used that ratio to identify a distinct chemical fingerprint for subducted crust.They devised a precise method of measuring that ratio using a mass spectrometer at the MagLab. Then they crunched the numbers to see how these ratios differed among the 30 regions sampled, expecting to see variations that would shed light on their origins.At first the analysis revealed nothing of note. Concerned, Yang, a doctoral candidate at the time, consulted with her adviser. Humayun suggested looking at the problem from a wider angle: Rather than compare basalts of different regions, they could compare enriched and depleted basalts.After quickly re-crunching the data, Yang was thrilled to see clear differences among those groups of basalts."I was very happy," recalled Yang, lead author on the paper. "I thought, 'I will be able to graduate!'"The team had detected lower germanium-to-silicon ratios in enriched basalts -- the chemical fingerprint for recycled crust -- across all the regions they sampled, pointing to its marble cake-like spread throughout the mantle. Essentially, they solved the mystery of the vanishing crust.It was a lesson in missing the forest for the trees, Humayun said."Sometimes you're looking too closely, with your nose in the data, and you can't see the patterns," he said. "Then you step back and you go, 'Whoa!'"Digging deeper into the patterns they found, the scientists unearthed more secrets. Based on the amounts of enriched basalts detected on global mid-ocean ridges, the team was able to calculate that about 5 to 6 percent of the Earth's mantle is made of recycled crust, a figure that sheds new light on the planet's history as a crust factory. Scientists had known the Earth cranks out crust at the rate of a few inches a year. But has it done so consistently throughout its entire history?Their analysis, Humayun said, indicates that, "The rates of crust formation can't have been radically different from what they are today, which is not what anybody expected."The MagLab is funded by the National Science Foundation and the State of Florida. It is headquartered at Florida State University with additional locations at University of Florida and Los Alamos National Laboratory.
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Geography
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June 26, 2020
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https://www.sciencedaily.com/releases/2020/06/200626114754.htm
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Unknown currents in Southern Ocean have been observed with help of seals
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Using state-of-the-art ocean robots and scientific sensors attached to seals, researchers in Marine Sciences at the University of Gothenburg have for the first time observed small and energetic ocean currents in the Southern Ocean. The currents are critical at controlling the amount of heat and carbon moving between the ocean and the atmosphere -- information vital for understanding our global climate and how it may change in the future.
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Two new studies, one led by Associate Professor Sebastiaan Swart and the other led by Dr Louise Biddle, both working at the University of Gothenburg, use highly novel techniques to collect rare data in the ocean both under and near the sea ice surrounding Antarctica.These papers present for the first time upper ocean currents of approximately 0.1-10 km in size. These currents, which are invisible to satellite and ship-based data, are seen to interact with strong Southern Ocean storms and with physical processes occurring under sea ice."Using the data collected by the seals, we're able to look at the impact these upper ocean currents have underneath the sea ice for the first time. It's a really valuable insight into what was previously completely unknown in the Southern Ocean," says Dr Louise Biddle, Department of Marine Sciences, University of Gothenburg.The winter had assumed to be a "quiet" time due to the dampening effect of sea ice on the ocean's surface. However, the two studies show that these upper ocean currents have a significant effect on the ocean during winter.Some of the findings by Sebastiaan Swart and his team gives further insight how these observed ocean currents work. Their study highlights that during times when there are no storms and winds are weak, upper ocean currents start to become much more energetic. This energy enhances the rate of ocean mixing and transport of properties, like heat, carbon and nutrients, around the ocean and into the deep ocean."These new ocean robots, so-called gliders, which we control by satellite for months at a time, have allowed us to measure the ocean at unprecedented high resolution. The measurements have revealed strong physical linkages between the atmosphere and ocean. It's pretty amazing we can remotely 'steer' these robots in the most far-flung parts of the world -- the ocean around Antarctica -- while collecting new science data," says Associate Professor Sebastiaan Swart, Department of Marine Sciences, University of Gothenburg.Together, these studies contribute to improving our understanding of small-scale ocean and climate processes that have impacts globally. These kinds of observations are a critical knowledge gap in the ocean that has an impact on various processes occurring at global scale, such as ecosystems and climate."We are excited to grow this research capability at the University of Gothenburg. This is really a world-leading direction we should be taking to collect part of our data in marine sciences," says Sebastiaan Swart.
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Geography
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June 26, 2020
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https://www.sciencedaily.com/releases/2020/06/200626092724.htm
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Maryland offshore wind farm could become stop-over for migrating sturgeon, striped bass
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For the endangered Atlantic sturgeon and the commercially and recreationally important striped bass, the Delaware-Maryland-Virginia coastal shelf serves as an important spring and fall "flyway." Typically thought of as an established aerial route used by migratory birds to travel between feeding and breeding grounds, a recent study by scientists at the University of Maryland Center for Environmental Science applies the term to fish species of concern. Authors suggest that the development of wind farms on the Delmarva coastal shelf, 17-26 miles from Ocean City's shoreline, may alter the migratory behavior of these fish as new wind turbines in this otherwise featureless region could create habitat around which fish linger.
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Studies within the Maryland Wind Energy Area -- the coastal shelf waters leased by the Bureau of Ocean Energy Management for offshore wind farms -- prior to construction activities reveal that Atlantic sturgeon and striped bass are frequent visitors. Seasonal trends lead scientists to believe that the wind energy area lies within an important migration corridor for both species. Atlantic sturgeon were most commonly observed moving through the area during the spring and fall, while striped bass had an increased migratory presence in spring and winter. The Atlantic sturgeons' "flyway" tended to favor shallower, warmer waters, while striped bass were more likely to be found at great depths and cooler conditions.Both species spent longer periods of time in the corridor during the autumn and winter. This trend was particularly strong for striped bass, with many individuals prolonging their presence on the outer shelf during winter. However, during the summer, Atlantic sturgeon were rarely detected and striped bass were absent.The construction of an off-shore wind farm creates loud noises and increased activity that can disrupt typical animal behaviors. The low occurrence of these important fish species during the summer months suggests a potential window for wind turbine construction, when impacts could be minimized."Scientists have learned a lot about the Atlantic sturgeon and striped bass' seasonal patterns of habitat selection within spawning rivers, estuaries, and shelf foraging habitats," says study author Ellie Rothermel, who recently received her master's degree from the University of Maryland Center for Environmental Science. "During these times, we know where the fish are likely to be and when to expect them there, but information on the location and timing of key coastal migrations is limited. Coastal waters have been largely inaccessible to scientists. Our study uses acoustic telemetry to understand the critical migratory periods in the lives of these fish species."Rothermel compares acoustic telemetry to the E-ZPass system used for vehicles. When a car with E-ZPass is driven over the Bay Bridge, a toll booth collects its identification number, along with the time and date. Just like toll booths and the E-Z Pass system, scientists use acoustic receivers and tags to track where fish go, and when they go there.After catching and determining the size, weight and sex of a striped bass, scientists surgically implanted an acoustic tag into the fish prior to releasing it. An acoustic tag is a small device, about the size of a thumb, that has a unique ID and makes a "ping" sound every few seconds.Scientists also deployed 20 acoustic receivers in the Maryland Wind Energy Area. When a tagged fish swims past a receiver, a listening device about the size of a liter soda bottle, the receiver records the "ping" sent out by the tag. Each "ping" transmits its unique ID and the depth at which the fish was swimming to the receiver, which also records the time and date. The array of receivers allows scientists to monitor the movements of tagged fish. During the study, "pings" from 352 individual Atlantic sturgeon and 315 individual striped bass were recorded by receivers.Scientists believe that Maryland's future offshore wind farm could become a stop-over region where striped bass and sturgeon might linger longer. The DelMarVa coastal shelf is a fairly barren area. The development of high relief wind turbines would provide structure around which fish may gather and linger during migrations."To extend the highway travel metaphor, the wind farm that will be built in the area off-shore from Ocean City may become a 'rest stop' where fish and sharks can grab a bite to eat and take a break before resuming their travels," says study co-author Dave Secor of the University of Maryland Center for Environmental Science.As wind farms are developed and operated offshore of the Mid-Atlantic and Southern New England regions, which together comprises a multispecies "flyway," scientists could use the telemetry array design to monitor potential impacts. Cooperation among researchers, expanded scale of acoustic telemetry arrays, and increased incorporation of oceanographic data will improve understanding of how fishes will respond to wind energy development in the northwest Atlantic Ocean.
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Geography
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June 28, 2020
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https://www.sciencedaily.com/releases/2020/06/200628094249.htm
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First completely remote at-sea science expedition in Australia's coral sea marine park
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Scientists working remotely with Schmidt Ocean Institute, one of the only at-sea science expeditions to continue operating during the global pandemic, have completed a first look at deep waters in the Coral Sea never before seen.
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The Australian science team discovered the deepest living hard corals in Eastern Australian waters, sighted fish in regions where they had never been found before, and identified up to 10 new marine species of fish, snails, and sponges.Schmidt Ocean Institute's research vessel Falkor -- the only year-round philanthropic research vessel in the world -- spent the last 46 days in one of the world's largest protected areas, the Coral Sea Marine Park.The team of Australian scientists connected remotely to the ship from their homes, collecting high-resolution seafloor maps and video footage of the deep ocean down to 1,600 meters. Led by chief scientist Dr. Robin Beaman of James Cook University, the expedition enabled the team to develop a better understanding of the physical and long-term changes that have occurred on the deep reefs. This marked the first time the region had been viewed, using an underwater robot that streamed real-time 4K video.The extraordinary mapping effort has illuminated a complex seafloor of 30 large coral atolls and banks, revealing submarine canyons, dune fields, submerged reefs, and landslides. More than 35,500 square kilometers were mapped-an area larger than half of Tasmania, transforming the Queensland Plateau from one of the poorest-mapped to one of the best-mapped frontier areas of Australia's marine estate. The maps created will be available through AusSeabed , a national Australian seabed mapping program, and will also contribute to the Nippon Foundation GEBCO Seabed 2030 Project . Only the shallower parts of these reefs had been mapped previously, and until now no detailed mapping data existed of the deeper areas."This expedition has provided us with a unique window into both the geological past and the present day conditions, allowing scientists and park managers to be able to see and tell the full story of the interconnected environments," said Dr. Beaman. "This vision is invaluable for science, management, and education."Over 91 hours of high-resolution video surveys were collected with Falkor's underwater robot, SuBastian, showing no evidence of coral bleaching below 80 meters."We know that the shallower coral counterparts are currently undergoing their third mass bleaching event in five years, so it's an invaluable insight for scientists and managers to know how deep that bleaching extends, " said Dr. Jyotika Virmani, executive director of Schmidt Ocean Institute. "It's important to note, however, that the corals discovered are specialized to these deep habitats and are not found in the shallows. This expedition was the first time these species have been recorded in such high abundance in the Coral Sea."The 14 historic deep sea dives completed with SuBastian have also helped give a much better understanding of the depth and habitat preferences of the Coral Sea deep reef community. All of the data collected has been publicly shared through more than 74 hours of video surveys and highlights available on the Schmidt Ocean Institute YouTube channel and website . The live streamed dives created an online platform, drawing spectators from around the world to witness unique species like deep water sharks and chambered nautiluses -- a distant cousin to squids that uses jet propulsion to move."The footage coming from our dives is just astounding, '' Virmani said. "The Falkor 's robust telepresence technology has allowed scientists from all over the world to collaborate on some of these discoveries. The data will greatly advance the characterization of Australia's massive and ecologically important marine estate."Research Vessel Falkor will return to the Coral Sea Marine Park for an additional month of research at the end of July.
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Geography
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June 25, 2020
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https://www.sciencedaily.com/releases/2020/06/200625102521.htm
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Spider baby boom in a warmer Arctic
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Climate change leads to longer growing seasons in the Arctic. A new study, which has just been published in
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Arctic spiders are at the top of the food chain among invertebrates and are numerous on the Arctic tundra. They typically take several years to become adults, and only produce offspring .But something is happening in the high north in these years. A lot, actually.Climate change is more dramatic here than in no other place on Earth. The average temperature is increasing significantly and this affects the ecosystems.Researchers have previously reported how plants bloom earlier and earlier in the season. There are also signs that species move farther north and up into the mountains.A team of researchers led by senior researcher Toke T. Høye from the Arctic Research Centre and Department of Bioscience at Aarhus University has now shown that changes are also occurring in the reproduction of invertebrates.For almost 20 years, researchers at the Zackenberg Research Station in north-eastern Greenland have caught wolf spiders as part of the monitoring programme Greenland Ecosystem Monitoring. The spiders were caught in small pitfall traps set up in different vegetation types.Wolf spiders carry their eggs in a so-called egg sac. The researchers counted the number of eggs in the individual spider's egg sacs and compared this information with the time of the season that the animal was caught. By looking at the distribution of the number of eggs in the egg sacs throughout the season, it became clear that in some summers the spiders produced two egg sacs -- a phenomenon that is known from warmer latitudes, but which has not previously been observed in the Arctic."We now have the longest time series of spiders collected the Arctic. The large amount of data allows us to show how small animals in the Arctic change their life history in response to climate change," says Toke T. Høye.The long time series tells the researchers that the earlier the snow disappears from the ground, the greater the proportion of spiders that can produce a second clutch of offspring."These changes in the life history have not been seen earlier and evidence suggests that the phenomenon plays an important role for Arctic insects and spiders," Toke T. Høye says.The researchers see the spiders' response to climate change as an ability to adapt to the new conditions.Wolf spiders feed on small organisms such as springtails in the soil. If there are more spiders -- or insects -- in the future Arctic, it can have an influence on the food chains on land."We can only speculate about how the ecosystems change, but we can now ascertain that changes in the reproduction of species are an important factor to include when we try to understand how Arctic ecosystems react to the rising temperatures on the planet," Toke T. Høye says.
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Geography
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June 24, 2020
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https://www.sciencedaily.com/releases/2020/06/200624172044.htm
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Changes in water of Canadian Arctic
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Melting of Arctic ice due to climate change has exposed more sea surface to an atmosphere with higher concentrations of carbon dioxide. Scientists have long suspected this trend would raise CO
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Now University of Montana researcher Michael DeGrandpre and his patented sensors have helped an international team determine that, indeed, COThe work was published this month in the journal DeGrandpre is a UM chemistry professor, and in 2015 he and the company he founded, Sunburst Sensors, won two coveted XPRIZE awards for developing inexpensive, durable sensors to better understand ocean acidification. Sunburst Sensor technology also was used in this recent study for a CODeGrandpre said ocean measurements are taken while the icebreaker is underway, sometimes crashing through ice one to two meters thick. DeGrandpre and UM research associate Cory Beatty have participated in these research cruises since 2012 with support from the National Science Foundation Office of Polar Programs."Because of the inaccessibility of the Arctic and the typically harsh work conditions, we really need a world-class icebreaker to access these areas," DeGrandpre said. "It also has given us a high-quality, consistent dataset, which really helped with this latest study. Most Arctic COHe said the new study combines sporadic data dating back to 1994 with the more-frequent data they have collected since 2012. DeGrandpre said their consistent dataset will only improve, as NSF recently awarded them an $890,000 grant to continue the icebreaker project through 2023.
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Geography
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June 24, 2020
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https://www.sciencedaily.com/releases/2020/06/200624151537.htm
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Adirondack boreal peatlands near southern range limit likely threatened by warmer climate
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A study published in the journal
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"Shingle Shanty Preserve was an ideal location to conduct this research," said Stephen Langdon, Shingle Shanty Director and principal investigator. "Peatlands, like those at Shingle Shanty Preserve, are some of the best protected, most-intact examples of the ecosystem around the world at this latitude: a fact that makes them a critical resource for understanding the biological response to climate change and nitrogen deposition." Langdon has 25 years of experience in the Adirondacks working in conservation from shovel-in-hand trail maintenance to biodiversity research with government and private organizations."These are hard-earned data," Langdon said. "The result of weeks of bushwhacking through buggy bogs and thick black spruce forests."Researchers collected data on vascular species, including their composition, environmental drivers, and ages in 50 plots spread throughout a nearly 1000-acre portion of the Preserve."A peatland complex of this size at its southern geographical limit in the eastern U.S. is highly significant ecologically and for its conservation values," said Don Leopold, ESF Distinguished Teaching Professor and research collaborator. Leopold has studied peatlands throughout the U.S. for the past 35 years.Large peatlands, like Shingle Shanty Preserve near their southern range limits in eastern North America, are particularly important for biodiversity conservation because they are nested in a relatively intact biome and they are a refuge for many disjunct boreal species at their southern range limits, like the threatened spruce grouse. The biodiversity in these peatlands is threatened by direct modification (e.g., drainage for agriculture) and by invasions of woody species linked to human-caused environmental changes such as climate warming and atmospheric nitrogen deposition"This research should serve as a wake-up call, as it provides an early warning that even the most remote and protected boreal peatlands may be lost at their southern range limits, in potentially just over a few decades, due to this ongoing and abundant colonization by temperate tree species -a process likely to be dramatically accelerated by continuously warming climate and fertilizing effects of nitrogen emissions," said Martin Dovciak, ESF Associate Professor and research collaborator. Dovciak has studied forest dynamics in a variety of forested ecosystems in North America and Europe over the last 25 years.Shingle Shanty Preserve is a 23-square-mile remote tract of land located in the middle of the 6-million-acre Adirondack Park, about nine miles west of Long Lake, NY. Although all of the Preserve is protected by a Forever Wild conservation easement, it is still quite susceptible to large-scale changes due to climate. The Preserve and Research Station was formally established as a 501(c)3 non-profit biological field research station in 2008 with a mission of supporting scientific research to improve the understanding and management of Adirondack Ecosystems. This remote, private Preserve is positioned at the top of the Beaver, Raquette and Moose River watersheds and has 2000 acres of pristine boreal wetlands, 9 lakes and ponds, 6 miles of headwater streams and over 12,500 acres of northern hardwood and successional northern hardwood forests. Shingle Shanty is home to numerous species that benefit from large scale protection, including a suite of boreal bird species such as spruce grouse, rusty black birds and olive-sided flycatchers, as well as moose, American martin and river otters. The Preserve is located in an unusually cold area for its latitude in the southernmost area of USDA hardiness Zone 3 in the northeastern United States. Temperature data loggers at the site recorded a growing season of only 19-days as recently as 2014 in the low-lying peatland complex.
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Geography
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June 23, 2020
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https://www.sciencedaily.com/releases/2020/06/200623145322.htm
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Tropical forest loss is increased by large-scale land acquisitions
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In recent years, there has been a rise in foreign and domestic large-scale land acquisitions -- defined as being at least roughly one square mile -- in Latin America, Asia, and Africa where investing countries and multinational investors take out long-term contracts to use the land for various enterprises.
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In some cases, this leads to the creation of new jobs for local communities, and governments often welcome these investments as a means to promote the transfer of technologies and the inflow of capital. But the investments can also have adverse outcomes for local people, who rely on the acquired areas for food and income but have no legal claim to the land, and the environment -- as the land will likely need to be converted to serve its intended use.An international group of researchers led by the University of Delaware's Kyle Davis has recently published a study in The study's findings show that large-scale land acquisitions can lead to elevated deforestation of tropical forests and highlight the role of local policies in the sustainable management of these ecosystems.Researchers used a georeferenced database of more than 82,000 land deals -- covering 15 countries in Latin American, sub-Saharan Africa and Southeast Asia -- with global data on annual forest cover and loss between 2000 and 2018.They found that since the start of the century, 76% of all large-scale land acquisitions in the Global South -- an emerging term which refers to the regions of Latin America, Asia, Africa and Oceania -- can be attributed to foreign land investment. These land acquisitions covered anywhere from 6% to 59% of a particular country's land area and 2% to 79% of its forests.The information came from the Global Forest Watch database run by the World Resources Institute as well as other sources such as government ministries, which provides information for thousands of individual investments that show the exact area, boundary and intended use."This collection of datasets on individual land investments provided me with information on the exact area, boundary, and intended use of each deal. I then combined these data with satellite information on forest cover and forest loss to understand whether large-scale land investments are associated with increased rates of forest loss," said Davis, assistant professor in the Department of Geography and Spatial Sciences in UD's College of Earth, Ocean and Environment and the Department of Plant and Soil Sciences in UD's College of Agriculture and Natural Resources.With regards to the environmental damage done by oil palm, wood fiber and tree plantations, Davis said a lot of it has to do with the ways in which those products are grown."Investments to establish new oil palm or tree plantations seem to consistently have higher rates of forest loss, and that makes sense because basically, you have to completely clear the land in order to convert it to that intended use," said Davis. "If you want to establish a tree plantation or a palm oil plantation in place of natural vegetation, you've first got to cut down the forest."For the other investment types, such as logging and mining, however, the results were much more mixed. Logging investments, in fact, served a small, protective role where the rates of forest loss in logging concessions were slightly lower than the rates of forest loss in surrounding, comparable areas. Davis attributed this to the specific requirements for the logging industry where only trees of a certain size or species can often be harvested.These large-scale land acquisitions are now widespread across the planet, which was caused largely by rising globalization and the world's increasing interconnectedness."There's been a rapid increase in land investments in recent decades due to growing global demands for food, fuel, and fiber," said Davis.He pointed to the global food crisis in 2008 when many import-reliant countries realized they were vulnerable to food or resource shortages. To help offset that vulnerability, they have pursued investments abroad to expand the pool of resources available to them in case another large-scale shock occurs.Davis emphasized the importance for governments to provide detailed information on land investments, to ensure that these deals were carried out transparently and to allow researchers to objectively assess their effects.He also said that by performing this comparison across different countries, it makes it possible to start identifying specific policies that are more effective in protecting forests."If you see deals in one country that aren't leading to enhanced forest loss but the same type of investment in another country is accelerating deforestation, then this suggests that there are opportunities to compare the policies in both places and leverage what's working in one country and adapt that to another context," said Davis. "But it also clearly shows that countries will inevitably experience deforestation should they seek to promote certain investments such as palm oil, wood fiber, and tree plantations, which we found were consistently associated with increased forest loss."
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Geography
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June 23, 2020
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https://www.sciencedaily.com/releases/2020/06/200623104240.htm
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New opportunities for ocean and climate modelling
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The continuous development and improvement of numerical models for the investigation of the climate system is very expensive and complex. At GEOMAR a new modular system has now been presented, which allows investigations to be carried in a flexible way, with varying levels of complexity. The system, called FOCI (Flexible Ocean and Climate Infrastructure), consists of different components that can be adapted and used, depending on the research question and available computing power.
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In their model simulations, climate researchers always have to make compromises. Even with the largest computers available worldwide, they can only reproduce the real world to a limited extent. Depending on the application, simplifications have to be made in the spatial resolution, but also in the physical processes represented by the model. While model experiments over periods of months to a few years can often still be made with high spatial resolution, integrations over centuries to millennia can only be performed at coarser resolution. In the past, models were developed for a specific purpose. Now, GEOMAR Helmholtz Centre for Ocean Research Kiel presented a flexible model kit, called FOCI (Flexible Ocean and Climate Infrastructure). It is based on the Earth system model of the Max Planck Institute for Meteorology in Hamburg and has been modified with the NEMO ocean model, in order to represent small-scale processes in the oceans at higher resolution."In FOCI we combine decades of expertise in ocean and climate modelling at GEOMAR. The new system enables the investigation of new questions such as the influence of the stratospheric ozone hole on the circulation in the Southern Ocean or the impact of the Gulf Stream on atmospheric processes," explains Professor Dr. Katja Matthes from the Maritime Meteorology Research Unit at GEOMAR."With the new system, we can investigate many different research questions on ar range of time scales," Professor Dr. Arne Biastoch, head of the Ocean Dynamics Research Unit at GEOMAR, points out. "We initially performed a set of standardised basic tests with the FOCI system," the oceanographer continues. "We had to find out whether the model system is capable of reproducing the observed climate and the present ocean circulation. Only if we are confident that the system can successfully simulate the present conditions within limited error bands it can be used to investigate unknown phenomena or for the predictions of future climate conditions." The results, which have been published in the international journal The basic experiments carried out so far include a control run over 1,500 years with pre-industrial greenhouse gas concentrations and several experiments covering the period from 1850 to the present day, for which observational data are available for verification. "The current results are very encouraging," says Katja Matthes. The system will be further improved and used for various questions to study natural climate fluctuations, but also anthropogenic climate change. "From our point of view, FOCI is the ideal system for GEOMAR to simulate small-scale processes in the ocean, interactions between stratosphere and troposphere as well as biogeochemical processes in the ocean. It also allows us to carry out complex projects such as a large number of model simulations over several decades with a reasonable amount of computing time," Professor Matthes concludes.
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Geography
| 2,020 |
June 22, 2020
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https://www.sciencedaily.com/releases/2020/06/200622133008.htm
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Research sheds new light on the role of sea ice in controlling atmospheric carbon levels
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A new study has highlighted the crucial role that sea ice across the Southern Ocean played in controlling atmospheric carbon dioxide levels during times of past climate change, and could provide a critical resource for developing future climate change models.
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For the study an international team of researchers, led by Keele University and including experts from the University of Exeter, demonstrated that seasonal growth and destruction of sea ice in a warming world enhances the amount of marine life present in the sea around Antarctica, which draws down carbon from the atmosphere and stores it in the deep ocean.Having captured half of all human-related carbon that has entered the ocean to date, the Southern Ocean around Antarctica is crucial for regulating carbon dioxide levels resulting from human activity, so understanding the processes that determine its effectiveness as a carbon sink through time are crucial to reducing uncertainty in future climate change models.To understand this process further, the researchers studied data relating to one period where atmospheric COThis occurred after the Last Ice Age, around 18,000 years ago, when the world transitioned naturally into the warm interglacial world we live in today.During this period, COThe cause of this plateau, which occurred around 14,600 years ago, is unknown, but understanding what happened during this period could be crucial for improving climate change projections.Professor John Love, from Exeter's Biosciences department and co-author of the study said: "My research group and I are very excited about being part of this important investigation. We developed new techniques in cell biology to find, collect and analyse the rare and very tiny particles and cells that had been frozen in the ice for millennia."Like flies in amber, these minute fragments give us a unique window into past events, enabling our colleagues in the Earth, Atmosphere and Ocean sciences to develop a better understanding of climate change then, and now."Lead author Professor Chris Fogwill, Director of Keele University's Institute for Sustainable Futures said: "The cause of this long plateau in global atmospheric COTo resolve this question, researchers travelled to the Patriot Hills Blue Ice Area of Antarctica to develop new records of evidence of marine life that are captured in ice cores, with support from Antarctic Logistics and Expeditions (ALE).Blue ice areas are the perfect laboratory for Antarctic scientists due to their unique topography. Created by fierce, high-density katabatic winds, the top layer of snow is effectively eroded, exposing the ice below. As a result, ice flows up to the surface, providing access to ancient ice below.Professor Chris Turney, a visiting Fellow at Keele's Institute for Liberal Arts and Sciences from UNSW Sydney said: "Instead of drilling kilometres into the ice, we can simply walk across a blue ice area and travel back through time."This provides the opportunity to sample large amounts of ice for studying past environmental changes in detail. Organic biomarkers and DNA from the Southern Ocean are blown onto Antarctica and preserved in the ice, providing a unique record in a region where we have few scientific observations."Using this approach the team discovered that there was a marked increase in the number and diversity of marine organisms present across the 1,900 year period when the COThis provides the first recorded evidence of increased biological productivity and suggests that processes in the high latitude Southern Ocean may have caused the COThis modelling revealed that the plateau period coincided with the greatest seasonal changes in sea ice during a pronounced cold phase across the Southern Ocean known as the Antarctic Cold Reversal. During this period, sea ice grew extensively across the Southern Ocean, but as the world was warming rapidly, each year the sea ice would be rapidly destroyed during the summer.The researchers will now use these findings to underpin the development of future climate change models. The inclusion of sea ice processes that control climate-carbon feedbacks in a new generation of models will be crucial for reducing uncertainties surrounding climate projections and will help society adapt to future warming.
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Geography
| 2,020 |
June 22, 2020
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https://www.sciencedaily.com/releases/2020/06/200622132937.htm
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Ice core research in Antarctica sheds new light on role of sea ice in carbon balance
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New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO
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Surrounding the remote continent of Antarctica, the Southern Ocean is one of the most important yet poorly understood components of the global carbon cycle. Having captured half of all human-related carbon that has entered the ocean to date, the Southern Ocean is crucial to regulating human-induced COAfter the Last Ice Age, around 18,000 years ago, the world transitioned naturally into the warm interglacial world we live in today. During this period, COOne period stands out: a 1,900-year plateau of near-constant CO"We found that in sediment cores located in the sea-ice zone of the Southern Ocean biological productivity increased during this critical period, whereas it decreased farther north, outside of the sea-ice zone," says Michael Weber, co-author of the study from the Institute for Geosciences at the University of Bonn. "It was now important to find out how climate records on the Antarctic continent depict this critical time period."To resolve this question researchers from Keele University, U.K., and the University of New South Wales (UNSW) in Sydney, Australia, travelled to the Patriot Hills Blue Ice Area to obtain new records of marine biomarkers captured in ice cores. Chris Fogwill, lead author of the study from Keele University, says "the cause of this long plateau in global atmospheric COBlue ice areas are created by fierce, high-density katabatic winds that erode the top layer of snow effectively and expose the ice below. As a result, ice flows up to the surface, providing access to ancient ice below. While most Antarctic researchers drill down into the ice to extract samples with a conventional ice core, this team used a different method: horizontal ice core analysis. Chris Turney (UNSW, Sydney) says "Instead of drilling kilometres into the ice, we can simply walk across a blue ice area to travel back through time. This provides the opportunity to sample large volumes of ice necessary for studying new organic biomarkers and DNA that were blown from the Southern Ocean onto Antarctica and preserved in the blue ice."The results demonstrated a marked increase in the number and diversity of marine organisms across the 1,900 year period of the COThe team will use this work to underpin the development of climate models that seek to improve our understanding of future climate change. The inclusion of sea ice processes that control climate-carbon feedbacks in a new generation of models will be crucial for reducing uncertainties surrounding climate projections and help society adapt to future warming.
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Geography
| 2,020 |
June 22, 2020
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https://www.sciencedaily.com/releases/2020/06/200622132933.htm
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Parallel evolution in three-spined sticklebacks
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A group of researchers from the University of Helsinki used novel and powerful methods to disentangle the patterns of parallel evolution of freshwater three-spined sticklebacks at different geographic scales across their distribution range. The group concludes that the conditions under which striking genome-wide patterns of genetic parallelism can occur may in fact be far from common -- perhaps even exceptional.
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The three-spined stickleback ("What is really remarkable in our results is that the repeatability of evolution in response to similar selection pressures in different oceans can be so different," says group leader Juha Merilä, Professor at the Faculty of Biological and Environmental Sciences, University of Helsinki.The genetic underpinnings of such parallel evolution have fascinated scientists for years, and they have discovered that the observed marine-freshwater differentiation is underlain by surprisingly parallel changes also at the genetic level. However, most studies on this topic have been based on either limited geographic sampling or focused only on populations in the Eastern Pacific region."As scientists, we are often tempted to provide simple narratives to extremely complex problems. What I liked the most about this project is that we did the exact opposite: we show that the story behind the three-spined stickleback's spectacularly fast adaptation to novel habitats may be more complex than previously thought. I think that deciphering the role of demographic history in shaping evolutionary adaptation is a necessary step in solving the mystery," says co-author Paolo Momigliano, postdoctoral researcher at the Faculty of Biological and Environmental Sciences, University of Helsinki.With novel and powerful methods, a group of researchers from the University of Helsinki disentangled patterns of parallel evolution of freshwater three-spined sticklebacks at different geographic scales across their distribution range. They found that the extraordinary level of genetic parallelism observed in the Eastern Pacific region is not observed in the rest of the species' range. In fact, they found approximately 10-fold higher levels of genetic parallelism in the Eastern Pacific compared to the rest of the world."I have been studying the worldwide population histories of the species in my PhD. We found their ancestral populations are residing in the Eastern Pacific. We predicted that the region harbours the source of ancestral genetic variations for parallel evolution, and such genetic variation could be lost during colonisation to the rest of the world, for instance in the Atlantic. These predictions were tested by both empirical and simulated data," explains first author Bohao Fang, PhD candidate from the Faculty of Biological and Environmental Sciences, University of Helsinki.Their simulations showed that this difference in the degree of parallelism likely depends on the loss of standing genetic variation -- the raw material upon which selection acts -- during the colonisation of the Western Pacific and Atlantic Oceans from the Eastern Pacific Ocean.This discrepancy could have been further accentuated by periods of strong isolation and secondary contact between marine and freshwater habitats in the Eastern Pacific, consistent with the group's results and the geological history of the area. This secondary contact likely happened after the colonisation of the Atlantic Basin, resulting in much more genetic variation available for local adaptation in the Eastern Pacific -- variation that never had the chance to spread to the Atlantic. In other words, the discrepancy in genetic patterns of parallel evolution between the two oceans is a result of the complex demographic history of the species, which involved range expansions and demographic bottlenecks."Our less assumption-burdened methods have been a key to quantifying parallel evolution at different geographic scales for the type of data that was available for this study. I thoroughly enjoy developing novel methods to study adaptation and evolution, and the idea that parallel evolution might be exceptional in the Eastern Pacific compared to the rest of the world has intrigued me for a long time. It was a lucky coincidence that I became a part of the Ecological Genetics Research Unit led by Juha Merilä where the samples to finally test this hypothesis became available," concludes Petri Kemppainen, co-first author, method developer, and postdoctoral researcher at the Faculty of Biological and Environmental Sciences, University of Helsinki.
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Geography
| 2,020 |
June 18, 2020
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https://www.sciencedaily.com/releases/2020/06/200618150257.htm
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Forest loss escalates biodiversity change
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New international research reveals the far-reaching impacts of forest cover loss on global biodiversity.
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The research, led by the University of Edinburgh and the University of St Andrews, investigated the impacts of forest loss on species and biodiversity over time and around the world, revealing both losses and gains in species.Focussing on biodiversity data spanning 150 years and over 6,000 locations, the study, published in the journal Forest loss amplifies the gains and losses of biodiversity - the numbers of individual plant and animal species, as well as the wider diversity and composition of ecosystems around the planet.Forests support around 80% of all species living on land, from eagles, bluebells, beetles, and many more. This biodiversity provides important ecosystem services and some species, such as the rosalia longicorn beetle, survive best in intact old forests. However, forests are being altered by human activities, for example deforestation for the cultivation of agricultural crops or the conversion to rangeland for grazing cattle. The research reveals that forest loss amplified both gains and losses in the abundance of different species as well as in the overall biodiversity.This study used the BioTIME and Living Planet biodiversity databases - that contain data collected by researchers working at sites around the world. Bringing together over 5 million records of the numbers of different plants and animals with information on both historic and contemporary peaks in forest loss, the researchers analysed the worldwide impacts of forest loss on biodiversity.The international research team discovered both immediate and delayed effects of forest loss on ecosystems, indicating that biodiversity responses to human impacts are diverse and play out across decades.Findings also reveal that some tropical areas experience more forest loss now than they have ever seen in the past, resulting in declining numbers of different animal species. In North America and Europe, the greatest loss of forests often occurred centuries ago, however even the smaller amounts of forest loss in the present day led to different biodiversity responses, escalating gains in certain species and losses in others.The pace at which biodiversity responds to forest loss varies from a few years, as is the case for many short-lived grasses, light-loving plants and insects, to decades for long-living trees and larger birds and mammals.For long-lived species, the effects of forest loss do not happen right away and could take decades to become apparent in the biodiversity data that scientists collect.Gergana Daskalova, PhD student in the School of GeoSciences at the University of Edinburgh and lead author of the study, said: "Biodiversity, the types of species like different plants and animals around the world, is always changing and the species we see on our forest walks today are likely different from the ones we saw growing up."We're harnessing the power of generations of scientists recording data as they walk through forests. This allowed us to find signals amidst the noise and pick apart the influence of forest loss from the natural variation in biodiversity over time."Surprisingly, we found that forest loss doesn't always lead to biodiversity declines. Instead, when we lose forest cover, this can amplify the ongoing biodiversity change. For example, if a plant or animal species was declining before forest loss, its decline becomes even more severe after forest loss. That same intensification of the signal was also true for increasing species."Changes in the biodiversity of the planet's forests matter because they will echo through how these landscapes look, the types of species they support and the benefits that forests provide for society like clean air and water."Dr Isla Myers-Smith, co-senior author, from the School of GeoSciences at the University of Edinburgh, continued: "To get a global picture of how the planet is changing we need to combine different types of information from observations of plants and animals on the ground through to satellite records of ecosystem change from space. Our study brings together these two perspectives to make new insights into how biodiversity responds when forests are lost around the world."Ecology is being reshaped by the new tools available to us as researchers. From satellite observations through to high-performance computers, we ecologists can now ask questions with larger and more complex datasets. We are now coming to a new understanding of how ecosystems are responding to human impacts around the planet."Dr Maria Dornelas, co-senior author from the School of Biology at the University of St Andrews, added: "Humans are undoubtedly changing the planet. Yet, global analyses of how biodiversity is changing over time, like our study, are revealing biodiversity changes are nuanced and variable."With a better understanding of the different ways, both positive and negative, in which forest loss influences biodiversity, we can improve future conservation and restoration of global ecosystems. Only with collaborative science combining datasets from around the world can we assess both the state of the world's forests, as well as the millions of plants and animals they support.
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Geography
| 2,020 |
June 18, 2020
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https://www.sciencedaily.com/releases/2020/06/200618102418.htm
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Fish fossils become buried treasure
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Rare metals crucial to green industries turn out to have a surprising origin. Ancient global climate change and certain kinds of undersea geology drove fish populations to specific locations. As remains of the fish fossilized, they accumulated valuable elements and these fossil beds became concentrated deposits of such metals. This discovery could aid future prospects for deposits of so-called rare-earth elements in other undersea locations.
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Did you know that key components for things like wind turbines, LEDs and rechargeable batteries rely heavily on a group of metals known as rare-earth elements and yttrium (REY)? At present, the world's supply of these metals mainly comes from mines in China; however, a large deposit near the Japanese island of Minamitorishima could soon help satisfy the ever-increasing demand. But how did the REY deposit get there and why that location?"That story begins back in time in the Eocene epoch 34.5 million years ago, about halfway between now and the time of the dinosaurs," said Assistant Professor Junichiro Ohta. "At that time, several things happened that led to the REY deposit. Firstly, vast amounts of nutrients accumulated in the deep ocean. Secondly, the planet underwent cooling which altered sea currents, stirring up these nutrient deposits. The seamounts then caused upwellings of nutrients delivering them to the fish, which thrived as a result."Surprisingly, it's these fish, or rather their fossilized remains around Minamitorishima, that account for the REY deposits. As the fish died and underwent fossilization, REY metals in the environment, which would otherwise remain diffuse, accumulate inside the fossils. The research group had previously made this fish-to-REY deposit connection, but how and when the fossil deposits formed was an open question until now."I'm really pleased we made this discovery by looking at fragments of bones and teeth," said Ohta. "It was a difficult but satisfying task dating the deposits by comparing fossils we uncovered against a database of fossils with known ages. Equally so was another way we dated the deposits, by measuring the ratio of osmium isotopes in seawater trapped in REY-rich mud and comparing those to established records."The story of fish that became a useful resource for renewable energy technology is, ironically, parallel to that of the ancient organisms that became oil, which led to the very problems renewable technologies now aim to solve. And how could this study help?"Based on this new theory for the genesis of REY deposits in the ocean, we can improve the way we find future deposits," said Ohta. "We can target the feet of large seamounts on the seabed, many of which are distributed from the western North Pacific Ocean to the Central Pacific Ocean, so are in theory accessible to Japan."The REY sources by Minamitorishima could sufficiently satisfy current global demand for hundreds of years. However, getting to them may be extremely difficult as the deposit is just over 5 kilometers below sea level, and at present no resource has ever been commercially mined from such a depth. Additional or alternative sources may be useful so improved ways to find them would be a great benefit.
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Geography
| 2,020 |
June 17, 2020
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https://www.sciencedaily.com/releases/2020/06/200617145947.htm
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Arctic Ocean acidification worse than previously expected
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The Arctic Ocean will take up more CO
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The ocean takes up large amounts of human-made COA study that was recently published in the scientific journal Ocean acidification negatively impacts organisms that build calcium carbonate skeletons and shells. In sufficiently acidic waters, these shells become unstable and begin to dissolve. "Our results suggest that it will be more difficult for Arctic organisms to adapt to ocean acidification than previously expected," says co-author Lester Kwiatkowski. A loss of these organisms is likely to impact the entire Arctic food chain up to fish and marine mammals.The international research team exploited the large divergence in simulated Arctic Ocean carbon uptake by current climate models. The researchers found a physical relationship across the models between the simulation of present-day Arctic sea surface densities and associated deep-water formation, with greater deep-water formation causing enhanced transport of carbon into the ocean interior and therefore enhanced acidification. Using measurements of Arctic sea surface density the research team was able to correct for biases in the models and reduce the uncertainty associated with projections of future Arctic Ocean acidification.
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Geography
| 2,020 |
June 17, 2020
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https://www.sciencedaily.com/releases/2020/06/200617121458.htm
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Antarctic sea ice loss explained in new study
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Scientists have discovered that the summer sea ice in the Weddell Sea sector of Antarctica has decreased by one million square kilometres -- an area twice the size of Spain -- in the last five years, with implications for the marine ecosystem. The findings are published this month (June 2020) in the journal
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Sea ice surrounding Antarctica provides an important habitat for many species including penguins and seals, which rely on it to access food and to breed.An international team of researchers studied satellite records of sea ice extent and weather analyses starting in the late 1970s to understand why summer sea ice in the Weddell Sea area of Antarctica has reduced by a third over the last five years. They found that ice loss occurred due to a series of severe storms in the Antarctic summer of 2016/17, along with the re-appearance of an area of open water in the middle of the 'pack ice' (known as a polynya), which had not occurred since the mid-1970s.Lead author Professor John Turner, a climate scientist at British Antarctic Survey, says:"Antarctic sea ice continues to surprise us. In contrast to the Arctic, sea ice around the Antarctic had been increasing in extent since the 1970s, but then rapidly decreased to record low levels, with the greatest decline in the Weddell Sea. In summer, this area now has a third less sea ice, which will have implications for ocean circulation and the marine wildlife of the region that depend on it for their survival."The ocean around Antarctica freezes and doubles the size of the continent in the austral winter, with the sea ice extent reaching over 18 million square kilometres by late September. Through the spring and summer, the sea ice almost completely melts in most parts of the Antarctic, with only the Weddell Sea retaining a significant amount of sea ice.There are few storms around the Antarctic in the austral summer, but in December 2016, a number of intense and unseasonal storms developed in the Weddell Sea and drew warm air towards the Antarctic, melting a large amount of sea ice. The ice-free ocean absorbed energy from the Sun and then created a warm ocean temperature anomaly that still persists today.The winter of 2016 also saw the development of a polynya in the Weddell Sea, a large area of open water within the sea ice, which also contributed to the overall decline in sea ice extent. This polynya was created by the strong winds associated with the storms and unprecedented warm ocean conditions.This recent rapid sea ice loss is affecting both the Weddell Sea ecosystem and the wider Antarctic wildlife/plants and animals. Many species, ranging from tiny ice algae and shrimp-like crustaceans called krill to seabirds, seals and whales, are highly adapted to the presence of sea ice. If the drastic changes observed continue, they will have repercussions throughout the food chain, from affecting nutrients to the reduction of essential habitat for breeding and feeding for vast numbers of animals, such as ice seals and some species of penguins.Author and ecologist Professor Eugene Murphy from British Antarctic Survey says:"The dramatic decline in sea ice observed in the Weddell Sea is likely to have significant impacts on the way the entire marine ecosystem functions. Understanding these wider consequences is of paramount importance, especially if the decline in ice extent continues."Because of the large year-to-year variability in Antarctic sea ice extent the scientists cannot be sure if the ice in the Weddell Sea will in the short-term recover to the values seen before 2016 or whether they are seeing the start of the expected long-term decline of sea ice.
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Geography
| 2,020 |
June 17, 2020
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https://www.sciencedaily.com/releases/2020/06/200617121435.htm
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Uncovering hidden flow patterns in coastal waters likely leads to faster disaster response
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Each year, the U.S. Coast Guard performs thousands of search and rescue missions at sea. In situations where every minute matters, it is critical to have the most efficient ocean modeling data and algorithms at hand.
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Researchers at Virginia Tech are part of a multi-institutional group using mathematical techniques with ocean models and experiments to better understand near-surface flow patterns and hidden flow structures. With more accurate modeling data, response teams can better predict the search area grid from the air, and reduce emergency response time when lives are on the line.Throughout this study, published in "From the moment they are alerted that someone is lost, search and rescue teams use sophisticated software to try to pinpoint the last known location in the water, factor in how much time has passed, and make their best prediction on how far they have drifted," said Shane Ross, professor in the Kevin T. Crofton Department of Aerospace and Ocean Engineering. "By improving the modeling of drifting objects in unsteady currents, search teams will have more efficient probability computations that enable them to set a tighter search grid and make faster, safer rescues."Current flow models used in search and rescue operations factor in ocean dynamics, weather prediction, and in-situ observations, such as self-locating datum marker buoys deployed from air. According to the research team, even with high-resolution ocean models and improved weather prediction, search and rescue planning is still based on conventional practices, and rescuers rely on their hunches as much as sophisticated prediction tools.Computational tools can predict how particles or objects are transported and reveal areas of the flow where drifting objects are likely to converge. In engineering terms, these patterns are called Lagrangian coherent structures. Unfortunately, calculating Lagrangian structures can often be time-consuming and computationally expensive.For use in disaster response scenarios, transient attracting profiles are easily interpreted and can be computed and updated instantaneously from snapshots of ocean velocity data. This eliminates very expensive and timely computation, especially when short-time predictions are critically important in search and rescue. After six hours, the likelihood of rescuing people alive drops significantly.These attracting profiles, where persons in the water are likely to collect, provide continuously updated and highly specific search paths. The inset shows a migrant boat that capsized on April 12, 2015 in the Mediterranean Sea.In order to prove the predictive influence of transient attracting profiles in coastal waters ? -- or identify the regions where objects or people are most likely to accumulate over a two- to three-hour period of time ? -- the research team conducted multiple field experiments off the coast of Martha's Vineyard in Massachusetts.Using both Coastal Ocean Dynamics Experiment drifters and 180-pound OSCAR Water Rescue Training manikins, targets were released around areas of predicted transient attracting profiles with GPS tracking devices that reported location every five minutes. Even without accounting for wind-drag or inertial effects, the researchers observed that the TRAPs invariably attracted the floating drifters and manikins in the water over a two- to three-hour period.Identifying transient attracting profiles on ocean surface velocity data can also have significant impact on the containment of environmental disasters, such as catastrophic oil spills. TRAPs provide critical information for environmental hazard response teams and have the potential to limit the spread of toxic materials and reduce damaging impact on the surrounding ecological systems.
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Geography
| 2,020 |
June 17, 2020
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https://www.sciencedaily.com/releases/2020/06/200617091017.htm
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Using sunlight to save satellites from a fate of 'space junk'
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No satellite stays the same once launched into space. How much it changes can go unnoticed -- until something bad happens.
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Carolin Frueh is among only a handful of researchers who have persisted in using a complex technique that can diagnose a problem from thousands of miles away based on how the satellite reflects sunlight."While you're driving a car, you can't get out of the car to check if something has fallen off or gotten damaged. But you know that there might be a problem," said Frueh (pronounced "free"), an assistant professor in Purdue University's School of Aeronautics and Astronautics."An operator might notice that a satellite is unstable or not charging properly. An outside perspective can tell if it's because something broke off, or if a panel or antenna is not properly oriented, for example."Not diagnosing the problem increases chances of losing or not being able to reestablish communication with the satellite. When communication is lost, a satellite could become pieces of debris that stay in space for hundreds of years or indefinitely unless actively removed.This "space junk" poses a danger to other spacecraft. There are about 100,000 pieces of debris larger than a penny orbiting Earth, according to a U.S. Strategic Command database.Space is a vacuum that immediately puts stress on a satellite. Constant transitions between the deep cold of Earth's shadow and the extreme heat of the sun also take a toll over time."You know everything about a satellite when it's on the ground. But that configuration changes because, to carry the satellite up, parts of it need to be folded in. Once in space, you want the panels unfolded, stably oriented toward the sun and the antenna pointed toward Earth," Frueh said."The longer a satellite is out there, the less you know about it."Satellites are almost always illuminated by the sun, apart from short transitions to Earth's shadow. The light that a satellite reflects can help reveal the solution to a structural malfunction.The method calls for using telescopes on Earth to collect the light reflected by a satellite or one of its parts. Because satellites are far away, these objects might simply appear as white dots even on a telescope image, similar to stars on a night sky.Changes in the brightness of a "dot" over time are recorded as light curves. These light curves are then processed and used to extract information about an object's appearance or rotational state.A video describing this research at Purdue is available on YouTube at Light curves could be a less expensive and more practical way to identify satellite problems compared with radar. While radar can get a more detailed image of a satellite if conditions are favorable and the satellite is at low altitudes, light curves can provide information no matter how far away the satellite is from Earth's surface. Light curves also passively rely on sunlight, whereas radar actively illuminates an object to make it visible.The more complex an object is, the harder it is to estimate or solve for what the object looks like using light curves. The results also can be ambiguous; what if a satellite component just looks broken because it's casting a shadow on itself?Identifying and characterizing human-made objects with light curves is so mathematically complex that more researchers, instead, use the technique to study asteroids. As natural bodies, asteroids have less diverse materials on the surface and fewer sharp edges, making the math somewhat simpler.But even partial answers from light curves could provide valuable information about a satellite.In 2015, Frueh's lab observed a mystery object known simply as "WT1190F" using the Purdue Optical Ground Station telescope. She and her collaborators discovered from light curves and associated modeling that the object was almost certainly human-made and a likely candidate for a piece of "Snoopy," a missing Apollo 10 lunar module. The mission was part of a test run ahead of the Apollo 11 landing in 1969, when Neil Armstrong walked on the moon.A team of astronomers confirmed that the findings suggested the object came from Snoopy. Successes like these show that improving space object identification with light curves might be worth the struggle. "It matters when we can say with 80% certainty what an object is, even though getting that answer can be extremely difficult. It would be far less helpful, but easier, to give a hundred different answers for what an object is, all with about 1% probability," Frueh said.Frueh's lab is working on improving the likelihood that a light curve successfully identifies and characterizes both simple and complex space objects.The goal is that in five to 10 years, the technique could not only reliably assist a satellite operator, but also provide full shape and rotation models even when no information or guesses about the object are available. These models would more clearly show the different surface materials and sharp edges of satellites, making them easier to identify.With funding from the Air Force Office of Scientific Research, Frueh is developing ways to use light curves to increase knowledge of human-made objects in the absence of information from a satellite operator.Information that light curves provide about satellites also could improve how they are designed in the future. Frueh's lab has identified objects orbiting Earth that appear to be the gold foil of satellites flaking off over time. These flakes could dangerously create tiny objects that are difficult to track."The whole idea is improving space situational awareness," Frueh said.
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Geography
| 2,020 |
June 16, 2020
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https://www.sciencedaily.com/releases/2020/06/200616200155.htm
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Seaweed takes scientists on trip 'through time' in the waters of Monterey Bay
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New research led by Monterey Bay Aquarium is helping to unlock the natural history of one of the most studied places on the planet. By tapping into a collection of dried, pressed seaweed -- that dates back more than 140 years -- researchers with the Aquarium's Ocean Memory Lab can now offer a window back in time to understand what the bay was like before the impacts of modern human activity.
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Read the paper, "Herbaria macroalgae as a proxy for historical upwelling trends in Central California," at the journal Deep marine canyons, a myriad migratory species and an abundant source of nutrients supplied by natural upwelling have attracted the massive concentration of marine science currently focused on Monterey Bay. Despite this proliferation of study and observation here, scientists had always been limited in their attempts to establish baselines of ecosystem health by the extent of available data, which in Monterey Bay extends back to 1946 when the patterns of its natural upwelling started being recorded."This part of California's Central coast is renowned for the sheer amount of marine life it can sustain. Even through the pressures of the past century, Monterey Bay is still teeming with birds, whales, fishes and seaweeds," said Monterey Bay Aquarium Chief Scientist Kyle Van Houtan. "These plants and animals were around long before scientists, so we thought if we could find historical samples we might learn something by extracting the information stored in their tissues."Using that approach, the Ocean Memory Lab generates new information about the ocean's past by combing through scientific collections, museums, and other historical archives. These repositories contain specimens of marine life that have data on ocean conditions locked within their fronds, feathers, shells and other tissues. Aquarium scientists use a variety of chemical analyses to unlock the data held within sample tissues to provide more accurate baselines, and help inform decisions intended to maintain or restore ocean health."We were able to add nearly seven decades of data, extracted from seaweed samples more than a century old, to better understand historical changes in Monterey Bay," said Emily Miller, the lead author of the study for the Aquarium and now a researcher at partner institution, the Monterey Bay Aquarium Research Institute. "This information offers us a new perspective on one of the features that makes Monterey Bay home to such diversity, its upwelling cycles. Documenting these patterns helps us to understand shifts in the foundation of the food web, and to make more informed conservation decisions in the future."Working with colleagues from Stanford University's Hopkins Marine Station and the University of Hawaii, Aquarium researchers based the study on data from the chemical analysis of pressed seaweed samples sourced from herbarium collections from several institutions, dating back to 1878, as well as freshly collected specimens. The samples analyzed came from six species of seaweed, also called macroalgae, that included giant kelp, rockweed, sea lettuce, and grape tongue."Izzy Abbott, who was professor of biology at Hopkins, helped to curate and build our collection of algae for over 25 years," said Stephen Palumbi, a professor of marine biology at Stanford University's Hopkins Marine Station. "She and the algae biologists that came before her knew that preserving specimens was vital. But it took this new approach from Monterey Bay Aquarium to dig into the very atoms of the algae and ask the kelp forest questions about the history of the oceans."Researchers calibrated the accuracy of their chemical analysis by comparing nitrogen stable isotopes from a red algae, Gelidium, with the Bakun upwelling index, a record of the natural Monterey Bay phenomenon going back to 1946. They found a high correlation between the index and data derived from the algae samples from 1946-2018, which demonstrated the nitrogen isotopes in the algae could be used to determine the upwelling pattern. Researchers then used older algae specimens to extend the Bakun upwelling index back to 1878, 70 years before it began being monitored.One of the research's novel findings, drawn from the additional seven decades of information offered within the seaweed samples, shed more light into ocean conditions in Monterey Bay during the sardine fishery's famous boom and bust in the 1940s and 1950s. Researchers documented poor upwelling conditions in Monterey Bay in the years immediately prior to the crash. This discovery adds a new dimension to an understanding of what role ecosystem changes may have played in the shift from a sardine-dominated system to one that is anchovy-dominated. It could also further inform how fishery management practices are implemented to respond to environmental conditions, something known as ecosystem-based management.
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Geography
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June 16, 2020
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https://www.sciencedaily.com/releases/2020/06/200616135818.htm
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Coal-burning in Siberia after volcanic eruption led to climate change 250 million years ago
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A team of researchers led by Arizona State University (ASU) School of Earth and Space Exploration professor Lindy Elkins-Tanton has provided the first ever direct evidence that extensive coal burning in Siberia is a cause of the Permo-Triassic Extinction, the Earth's most severe extinction event. The results of their study have been recently published in the journal
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For this study, the international team led by Elkins-Tanton focused on the volcaniclastic rocks (rocks created by explosive volcanic eruptions) of the Siberian Traps, a region of volcanic rock in Russia. The massive eruptive event that formed the traps is one of the largest known volcanic events in the last 500 million years. The eruptions continued for roughly two million years and spanned the Permian-Triassic boundary. Today, the area is covered by about three million square miles of basaltic rock.This is ideal ground for researchers seeking an understanding of the Permo-Triassic extinction event, which affected all life on Earth approximately 252 million years ago. During this event, up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct.Calculations of sea water temperature indicate that at the peak of the extinction, the Earth underwent lethally hot global warming, in which equatorial ocean temperatures exceeded 104 degrees Fahrenheit. It took millions of years for ecosystems to be re-established and for species to recover.Among the possible causes of this extinction event, and one of the most long-hypothesized, is that massive burning coal led to catastrophic global warming, which in turn was devastating to life. To search for evidence to support this hypothesis, Elkins-Tanton and her team began looking at the Siberian Traps region, where it was known that the magmas and lavas from volcanic events burned a combination of vegetation and coal.While samples of volcaniclastics in the region were initially difficult to find, the team eventually discovered a scientific paper describing outcrops near the Angara River. "We found towering river cliffs of nothing but volcaniclastics, lining the river for hundreds of miles. It was geologically astounding," says Elkins-Tanton.Over six years, the team repeatedly returned to Siberia for field work. They flew to remote towns and were dropped by helicopter either to float down rivers collecting rocks, or to hike across the forests. They ultimately collected over 1,000 pounds of samples, which were shared with a team of 30 scientists from eight different countries.As the samples were analyzed, the team began seeing strange fragments in the volcaniclastics that seemed like burnt wood, and in some cases, burnt coal. Further field work turned up even more sites with charcoal, coal, and even some sticky organic-rich blobs in the rocks.Elkins-Tanton then collaborated with fellow researcher and co-author Steve Grasby of the Geological Survey of Canada, who had previously found microscopic remains of burnt coal on a Canadian arctic island. Those remains dated to the end-Permian and were thought to have wafted to Canada from Siberia as coal burned in Siberia. Grasby found that the Siberian Traps samples collected by Elkins-Tanton had the same evidence of burnt coal."Our study shows that Siberian Traps magmas intruded into and incorporated coal and organic material," says Elkins-Tanton. "That gives us direct evidence that the magmas also combusted large quantities of coal and organic matter during eruption."And the changes at the end-Permian extinction bear remarkable parallels to what is happening on Earth today, including burning hydrocarbons and coal, acid rain from sulfur, and even ozone-destroying halocarbons."Seeing these similarities gives us extra impetus to take action now, and also to further understand how the Earth responds to changes like these in the longer term," says Elkins-Tanton.
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Geography
| 2,020 |
June 16, 2020
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https://www.sciencedaily.com/releases/2020/06/200616135802.htm
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Seafood helped prehistoric people migrate out of Africa
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Prehistoric pioneers could have relied on shellfish to sustain them as they followed migratory routes out of Africa during times of drought, a new study suggests.
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The study examined fossil reefs near to the now-submerged Red Sea shorelines that marked prehistoric migratory routes from Africa to Arabia. The findings suggest this coast offered the resources necessary to act as a gateway out of Africa during periods of little rainfall when other food sources were scarce.The research team, led by the University of York, focused on the remains of 15,000 shells dating back 5,000 years to an arid period in the region. With the coastline of original migratory routes submerged by sea-level rise after the last Ice Age, the shells came from the nearby Farasan Islands in Saudi Arabia.The researchers found that populations of marine mollusks were plentiful enough to allow continuous harvests without any major ecological impacts and their plentiful availability would have enabled people to live through times of drought.Lead author, Dr Niklas Hausmann, Associate Researcher at the Department of Archaeology at the University of York, said: "The availability of food resources plays an important role in understanding the feasibility of past human migrations -- hunter-gatherer migrations would have required local food sources and periods of aridity could therefore have restricted these movements."Our study suggests that Red Sea shorelines had the resources necessary to provide a passage for prehistoric people."The study also confirms that communities settled on the shorelines of the Red Sea could have relied on shellfish as a sustainable food resource all year round.Dr Hausmann added: "Our data shows that at a time when many other resources on land were scarce, people could rely on their locally available shellfish. Previous studies have shown that people of the southern Red Sea ate shellfish year-round and over periods of thousands of years. We now also know that this resource was not depleted by them, but shellfish continued to maintain a healthy population."The shellfish species found in the archaeological sites on the Farasan Islands were also found in abundance in fossil reefs dating to over 100 thousand years ago, indicating that these shellfish have been an available resource over longer periods than archaeological sites previously suggested.Co-author of the study, Matthew Meredith-Williams, from La Trobe University, said: "We know that modelling past climates to learn about food resources is extremely helpful, but we need to differentiate between what is happening on land and what is happening in the water. In our study we show that marine foods were abundant and resilient and being gathered by people when they couldn't rely on terrestrial food."
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Geography
| 2,020 |
June 16, 2020
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https://www.sciencedaily.com/releases/2020/06/200616100829.htm
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Researchers uncover mysterious tanaids
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Tanaids are one of the most underappreciated animals in the world. These small crustaceans can be found in virtually all marine benthic habitats, from mangroves, rocky shores and coral reefs along the coasts to mud volcanoes, cold seeps and trenches in the deepest oceans. They even inhabit the shell surfaces of sea turtles, live inside gastropod shells like hermit crabs, and reside under the skin of deep-sea sea cucumbers.
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When present, tanaids are often one of the dominant animals in the community. Due to their sheer number, tanaids are likely to play important ecological roles but information on their biology remains elusive. The knowledge gaps include answers to the most basic questions -- How many species are there? What are their names? Experts have estimated that there could be up to 57,000 tanaidacean species worldwide. Currently, however, less than 1,500 species have been described, and the majority of these are in the temperate environments.Research Associate Mr Chim Chee Kong and Research Assistant Ms Samantha Tong from the Tropical Marine Science Institute at the National University of Singapore (NUS) are on a quest to discover more of these nameless taxa, specifically in the relatively species-rich but poorly studied tropical Indo-Pacific.Both researchers recently described two new species found in the abyssal polymetallic nodule fields in the eastern Pacific Ocean during a 2015 expedition. One of them was named Unispinosus eopacificus after the locality of where it was discovered, and the other was named Portaratrum birdi in honour of a leading tanaidacean taxonomist. They also erected the genus Unispinosus in the same paper, which was published in the journal The discovery of these two new species are of significant importance for environmental management because they were found in the Clarion-Clipperton Zone (CCZ), an understudied area in the middle of the Pacific Ocean characterised by polymetallic nodule fields. These fields contain commercially valuable metals such as nickel, copper, and rare earth elements that were formed over millions of years."Data on the biodiversity in this resource-rich region can allow the International Sea Authority to make well-informed decisions on whether to prioritise certain areas for conservation," explained Ms Tong.Many tanaids new to science were also uncovered during another deep-sea expedition in South Java in 2018, and are in the process of being described by Mr Chim and Ms Tong.With access to a large amount of local material, primarily collected during the Comprehensive Marine Biodiversity Survey conducted in 2013, the two NUS researchers have also been able to identify more tanaids in local waters. To date, Mr Chim has identified more than 20 species of tanaids from local waters and, as a result, raised the current knowledge of our natural heritage. Prior to this study, only one tanaid species had been formally recorded from Singapore waters, based on specimens that were collected in the 1900s.Last year, he and Ms Tong described an unusual tanaidacean species found in Singapore that were living inside dead barnacles, which is a novel microhabitat recorded for this group of crustaceans. The findings on the newly named Xenosinelobus balanocolus were reported in the journal "Taxonomic studies are extremely time-consuming, especially for microscopic animals such as tanaids, but at the same time, they are very rewarding as the results provide the strong foundation for further scientific hypotheses to build upon," said Mr Chim, who is also a part-time doctoral student at the Department of Biological Sciences at the NUS Faculty of Science.
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Geography
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June 15, 2020
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https://www.sciencedaily.com/releases/2020/06/200615152106.htm
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A carbon sink shrinks in the Arctic
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New research by University of Delaware doctoral student Zhangxian Ouyang and oceanographer Wei-Jun Cai, and an international team of researchers, demonstrates that rapid warming and sea-ice loss have induced major changes in the western Arctic Ocean.
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The research team's findings -- published Monday, June 15 in Arctic Ocean sea-ice loss is a critical consequence of climate change. As sea ice continues to melt in the western Arctic Ocean, more fresh water is entering the upper portion of the water in the Canada Basin, which sits off the coast of Alaska and Canada, south of the Chukchi Shelf.This summertime melt cycle is exacerbating seasonal changes and increasing the amount of carbon dioxide present in the water's topmost layer, which comprises the upper 70 feet of the water column. This is reducing the basin's capacity to remove carbon dioxide from the atmosphere.Prevailing thought, based on data measurements from under the ice and in newly melted ocean margin areas in the 1990s and early 2000s, had suggested that when the ice melted it would allow the Arctic Ocean to draw large amounts of carbon dioxide out of the atmosphere, acting as a carbon sink and helping to mitigate greenhouse gases. However, this may not be the case in all places, particularly in the Canada Basin where summer ice retreat has advanced into the deep basin since 2007.The research team's latest findings are based on an analysis of over 20 years of global data sets collected between 1994-2017 by researchers across the United States, China, Japan and Canada. They provide a more accurate depiction of what is happening in this region and build on Cai's previous work from 2010, which indicated that carbon dioxide levels at the sea surface increase rapidly and unexpectedly toward levels found in the atmosphere in newly ice-free Arctic Ocean basins.For example, the research team's work showed that as the ice breaks up and melts in the Canada Basin, this meltwater lays on top of the sea surface, creating a "blanket" of sorts that inhibits the ocean's ability to absorb carbon dioxide from the atmosphere into the deep ocean and store it there. Cai's team refers to this phenomenon as a "new normal" that is created by extreme seasonal warming and meltwater in the region."As carbon dioxide accumulates in the surface layer of the water from melting ice, the amount of carbon dioxide this area of the Arctic Ocean can take from the atmosphere will continue to shrink," said Cai, the Mary A.S. Lighthipe Professor in the College of Earth, Ocean and Environment. "We predict by 2030, the Canada Basin's ability to serve as a carbon sink will be really minimal."Additionally, this rapid increase of carbon dioxide content in the basin may have rapidly acidified the surface water, a process that can endanger marine calcifying organisms and disrupt ecosystem functioning there.In stark contrast, farther south in the shallow Chukchi Sea, the amount of carbon dioxide in the water's topmost layer remains very low, much lower than what is present in the atmosphere. This means that as air passes over the water's surface, the sea can more quickly absorb carbon dioxide from the air.The researchers suggest that this difference is the result of high biological production in the Chukchi Sea due to rich nutrients being transported there on currents coming from the Pacific Ocean since the Bering Strait has opened up due to earlier ice loss. These nutrients enable abundant growth of phytoplankton and other marine organisms that form the base of the marine food web and feed the broader ecosystem. Phytoplankton also consume carbon dioxide dissolved in the water during photosynthesis, allowing more carbon dioxide to be taken from the surrounding atmosphere.The research team suspects that the Chukchi Sea will become a larger carbon sink in the future and impact the deep ocean carbon cycle and ecosystem, while the Canada Basin likely will remain less so as sea ice in the region continues to melt and change the water chemistry.According to Lisa Robbins, a retired senior scientist with the United States Geological Survey (USGS) and a co-author on the paper, these changes could have important implications for organisms in the Arctic. For instance, Arctic cod is an important fishery in the western Arctic that contributes to the region's overall economy and serves an important role in the marine food web as a food source for other organisms, such as Beluga whales and ringed seals. Biologists have noted that as temperature and sea ice melt have increased, Atlantic cod are responding by moving farther north. Changing water chemistry also may be playing a role, said Robbins, who led three expeditions to study the region's water chemistry in the Arctic aboard the United States Icebreaker R/V Healy while with the USGS.Long-term data sets, such as those used in this study, are key to understanding and predicting future changes in the Arctic."The amount of insight we get from these data sets into how our earth-ocean works is tremendous. If scientists hadn't collected data in 1994, we wouldn't have a place to start and compare with," said Robbins, now a courtesy professor in the College of Marine Science at University of South Florida.A 2019 article in Wired magazine found that in northern Canada near Greenland, glacial meltwater seems to be aiding watersheds in absorbing carbon dioxide from the atmosphere. While alone it cannot counterbalance the amount of carbon dioxide in the atmosphere due to carbon emissions, it is an important illustration that the changes aren't uniform and the subsequent effects -- positive and negative -- are the result of a complex combination of multiple different drivers. Further research and more international collaborative efforts can help to answer challenging unanswered questions.As sea-ice loss accelerates, the researchers expect these seasonal variations will cause the ocean water in the Canada Basin to have high levels of carbon dioxide and become increasingly acidic. This will further reduce the basin's capacity to take up carbon dioxide from the atmosphere and potentially reduce its capacity to mitigate climate change.While this problem might seem very far away from Delaware, it's important to remember that the ocean is one global system with circulation currents that transport water around the world, even to the Atlantic Ocean on the East Coast. And greenhouse gases are a global issue.Understanding how fundamentally important ice melt is to driving carbonate chemistry and seasonal changes in carbon dioxide in this region of the Arctic Ocean will help advance the science in this area, maybe not immediately but over the long-run, said Cai."We are trying to understand the processes at work and if the Arctic Ocean will continue to be a large carbon sink, while providing data that can help Earth systems modelers to predict global changes to the carbon cycle, and the ocean's biology and water chemistry," Cai said.This work is funded by multiple nations, including Cai's work which is supported through the National Science Foundation's Arctic Natural Science Program.Co-authors on the paper include researchers at The Third Institution of Oceanography (China), Columbia University, University of Montana, Ocean University of China, Japan Agency for Marine-Earth Science and Technology, University of South Florida and the International Arctic Research Center.
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Geography
| 2,020 |
June 15, 2020
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https://www.sciencedaily.com/releases/2020/06/200615140923.htm
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Clues to a dramatic chapter of Earth's geological history
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Imagine Earth completely covered in ice. While it's hard to picture all of today's oceans and land masses obscured with glaciers, such an ice-covered version of the planet was not so far-fetched millions of years ago.
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Lasting from approximately 1,000 to 540 million years ago, the dramatic chapter is an important part of Earth's 4.5-billion-year history. Known as the Neoproterozoic Era, the period of severe glaciation was a time when multicellular organisms were beginning to diversify and spread across the planet.Many researchers posit that ice may have covered every surface of the planet, stretching from the poles all the way to the hot tropics of the equator -- a hypothesis known as "Snowball Earth."How was it possible there was global ice -- even in the warmest areas of Earth?Researchers from the University of Rochester are shedding new light on that question. By analyzing mineral data left by glaciers before the onset of the Neoproterozoic Era, Scott MacLennan, a postdoctoral research associate in the lab of Mauricio Ibanez-Mejia, an assistant professor in the Department of Earth and Environmental Sciences, present the first geological evidence that Earth may have had a cool climate before Snowball Earth.The study, published in "This is a fascinating period, as these dramatic environmental changes happened right as the first true animals were beginning to appear and evolve on Earth," Ibanez-Mejia says.A critical aspect of understanding a period of planetwide glaciation is determining what the climate was like before Snowball Earth. Computer models indicate that a cool global climate was necessary in order to initiate a Snowball Earth state, but such a state has not been confirmed by geological evidence. Instead, geological evidence has previously suggested that Earth had a warm and ice-free climate immediately prior to the Neoproterozoic glaciation.While scientists don't know the exact mechanisms that may have caused Snowball Earth, they suspect that whatever they were, the mechanisms involved a massive decrease in atmospheric carbon dioxide concentrations. There are several scenarios in which the atmospheric carbon dioxide may have decreased. They include an increase in biomass in the oceans, which may have taken carbon dioxide out of the atmosphere and turned it into organic matter, or an increase in the weathering of the continental crust, which also takes up carbon dioxide.In order to determine whether these scenarios are feasible, however, it's critical to know more about Earth's climate before the massive glaciation events started."If the Earth was very hot, it would mean the ocean was storing a lot of heat, which would take a lot of time to get rid of in order to create a Snowball Earth," MacLennan says.Scientists can determine Earth's climate at points in time by studying rocks that were deposited at different times throughout Earth's history. MacLennan and his colleagues used zircon dating methods to very precisely date glacial rocks found in modern-day Virginia. Paleomagnetic data, which allows researchers to determine where the continents were located thousands and even millions of years ago, have established that Virginia was located in the middle of a supercontinent within the tropics while the glacial rocks were being deposited. The supercontinent later broke up into smaller parts.The researchers discovered that the glacial rocks were actually deposited 30 million years before the first Snowball Earth. The observation was surprising because they had expected the glacial rocks to be related to the Snowball Earth event. Instead, the discovery indicates that there were glaciers in the tropics near the equator -- albeit at potentially high altitudes -- even before Snowball Earth."The planet always gets colder away from the tropics and toward the poles because Earth receives most of its incoming sunlight at the equator," MacLennan says. "If there are glaciers in the tropics, the rest of the planet must have also been very cold. This means that our previous vision of a hot, humid world before the Snowball Earth is probably incorrect."The potential trigger mechanism for the massive global cooling therefore may not have been as extreme as some researchers believe; the planet didn't immediately turn from a warm state to a frozen state but instead appears to have experienced a more gradual cool-off into a Snowball Earth state.This research raises interesting questions about what Earth was really like 800 to 700 million years ago, before Snowball Earth events, during a time when interesting biological innovations were taking place as multicellular organisms were beginning to diversify."There have been a lot of questions about how multi- and single-cellular life forms would survive the Snowball Earths, especially if there was a rapid transition from a hot greenhouse world," MacLennan says. "Our estimates for pre-Snowball climate imply the planet was probably colder than the modern world, which means there may have been ample cold environments at high latitude and altitude where organisms could have adapted to these cold conditions."
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Geography
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June 15, 2020
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https://www.sciencedaily.com/releases/2020/06/200615140910.htm
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New fossil discovery shows 50 million-year-old Canada-Australia connection
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The discovery of a tiny insect fossil is unearthing big questions about the global movement of animals and the connection to changes in climate and shifting continents across deep time. The fossil, estimated to be 50 million years old, was found in rocks near the city of Kamloops, British Columbia, but today its relatives live exclusively in Australia.
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The finding is the latest in a pattern of discoveries that are leading experts to contemplate a Canada-Australia connection not previously considered. Paleontologists Bruce Archibald of Simon Fraser University and the Royal British Columbia Museum and Vladimir Makarkin of the Russian Academy of Sciences in Vladivostok published their findings in According to Makarkin, the fossil is part of the "split-footed lacewing" family. Little is known about this group over the 66-million-years following the extinction of the dinosaurs. "These fossils are rare," he says. "This is only the fourth one found from this time-span world-wide, and it's the most completely preserved. It adds important information to our knowledge of how they became modern."The paleontologists identified the fossil by the characteristic network of veins covering its wings. They emphasize that fossils like the new lacewing species help in understanding large-scale patterns of the modern distribution of life across the globe.Previous fossil insects of this age found in B.C. and neighbouring Washington have shown connections with Pacific-coastal Russia to the west and with Europe to the east -- patterns that are not surprising since the northern continents were connected then."Fifty million years ago, sea levels were lower, exposing more land between North America and Asia, and the Atlantic Ocean had not widened, leaving Europe and North America still joined across high latitudes," says Archibald. He explains that the far-north experienced warmer climates then as well, helping a variety of animals and plants to disperse freely between northern continents.The Australian connection is more puzzling though, as there is no such clear land connection. That continent was closer to Antarctica then and farther from Asia than today, leaving formidable ocean barriers for life to disperse between it and Canada's west coast.This lacewing joins other insect fossils from B.C. and Washington whose modern relatives only live in the Australian region. These include bulldog ants, a family of termites, and a kind of parasitoid wasp.Archibald says that "a pattern is emerging that we don't quite understand yet, but has interesting implications."The researchers suggest that the answer might be connected to climate. The forests of the ancient British Columbian temperate upland where this lacewing lived had very mild winters, in fact, probably without frost days.The climate of modern Australia shares these mild winters even in temperate regions. "It could be that these insect groups are today restricted to regions of the world where climates in key ways resemble those 50 million years ago in the far western Canadian mountains," says Archibald.Archibald and Makarkin emphasise that it's important to understand the little things in order to appreciate the big picture. "The more we know about these insects, the more we can piece together the history of how climate and the movement of continents have shaped global patterns of the distributions of life that we see in our modern world," says Makarkin."To understand where we are today and where we may be going with the big changes that we are seeing in global climates, we need to understand what's happened in the deep past."
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Geography
| 2,020 |
June 15, 2020
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https://www.sciencedaily.com/releases/2020/06/200615140854.htm
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Carbon emission from permafrost soils underestimated by 14%
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Picture 500 million cars stacked in rows. That's how much carbon -- about 1,000 petagrams, or one billion metric tons -- is locked away in Arctic permafrost.
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Currently, scientists estimate that 5-15% of the carbon stored in surface permafrost soils could be emitted as the greenhouse gas carbon dioxide by 2100, given the current trajectory of global warming. This emission, spurred by microbial action, could lead to 0.3 to 0.4 degrees Celsius of additional global warming.But this estimation is missing a crucial path that carbon dioxide may be entering the atmosphere: sunlight.According to a University of Michigan study, organic carbon in thawing permafrost soils flushed into lakes and rivers can be converted to carbon dioxide by sunlight, a process known as photomineralization.The research, led by aquatic geochemist Rose Cory, has found that organic carbon from thawing permafrost is highly susceptible to photomineralization by ultraviolet and visible light, and could contribute an additional 14% of carbon dioxide into the atmosphere. Her team's study is published in the journal "Only recently have global climate models included greenhouse gases from thawing permafrost soils. But none of them contain this feedback pathway," said Cory, an associate professor of earth and environmental sciences."To get a number on how much carbon could be released from permafrost soils through oxidation, we have to understand what are the processes and what is the timescale: maybe this carbon is just so resistant to oxidation that, even if thawed out, it would just flow into the Arctic ocean and be buried in another freezer."This pathway has been debated because measuring how sunlight degrades soil carbon is difficult. Each wavelength of light has a different effect on soil organic carbon, as does the level of iron in the soil. To precisely measure how carbon dioxide is emitted when organic carbon is exposed to sunlight, Cory's co-corresponding author Collin Ward, a scientist at Woods Hole Oceanographic Institution and U-M alum, developed a method to measure each wavelength's effect on soil organic carbon. To do this, he built a new instrument that uses LED lights to mimic different wavelengths of the sun."This new LED-based method makes it far easier and cheaper to figure out how light-driven reactions vary for different wavelengths of the sun," Ward said. "After I built the instrument I immediately called Rose and told her that I wanted to first use it on permafrost samples."The researchers placed organic carbon leached from soil samples from six Arctic locations in the instrument, and then subjected the samples to the LED light. After the light exposure, they extracted the carbon dioxide cryogenically and used a mass spectrometer to measure the age and amount of carbon dioxide given off by the soil carbon.They found that not only did the wavelength of sunlight impact the amount of carbon dioxide released, the amount of iron in the sample did as well. Iron acted as a catalyst, increasing the reactivity of the soil."What we have long suspected is that iron catalyzes this sunlight-driven process, and that's exactly what our results show," Cory said. "As the total amount of iron increases, the amount of carbon dioxide increases."Cory's team also used carbon dating to age the soil organic carbon and the carbon dioxide emitted from it to demonstrate this oxidation was happening to ancient permafrost, not just soil that thaws annually. This is important because soil that thaws annually would release a much smaller amount of carbon dioxide than what's available in permafrost.The researchers found that it was between 4,000 and 6,300 years old, and by demonstrating how old the soil is, they show that permafrost carbon is susceptible, or labile, to oxidation to carbon dioxide."Not only do we have the first wavelength specific measurement of this sunlight-driven reaction but we have verification that it's old carbon that is oxidized to carbon dioxide," Cory said. "We can put to rest any doubt that sunlight will oxidize old carbon and we show what is controlling this process -- it's the iron that catalyzes the sunlight oxidation of ancient (or old) carbon."Including the U-M team's finding into climate change models means that -- conservatively -- there could be a release of 6% of the 100 billion metric tons of carbon currently stored in Arctic permafrost. If 6% doesn't sound like much, consider that's the carbon equivalent of approximately 29 million cars evaporating into the atmosphere.
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Geography
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June 15, 2020
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https://www.sciencedaily.com/releases/2020/06/200615140829.htm
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The many lifetimes of plastics
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Many of us have seen informational posters at parks or aquariums specifying how long plastics bags, bottles, and other products last in the environment. They're a good reminder to not litter, but where does the information on the lifetime expectancy of plastic goods come from, and how reliable is it?
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It turns out, getting a true read on how long it takes for plastic to break down in the environment is tricky business, says Collin Ward, a marine chemist at Woods Hole Oceanographic Institution and member of the its Microplastics Catalyst Program, a long-term research program on plastics in the ocean."Plastics are everywhere, but one of the most pressing questions is how long plastics last in the environment," he says. "The environmental and human health risks associated with something that lasts one year in the environment, versus the same thing that lasts 500 years, are completely different."Knowing the fate of plastics may be tricky, but it's critical. Consumers need the information to make good, sustainable decisions; scientists need it to understand the fate of plastics in the environment and assess associated health risks; and legislators need it to make well-informed decisions around plastic bans.The long-standing mystery around the life expectancy of plastic goods has prompted a new study from Woods Hole Oceanographic Institution looking at how the lifetime estimates of straws, cups, bags, and other products are being communicated to the public via infographics. Ward, the lead author of a new paper published in the journal "The estimates being reported to the general public and legislators vary widely," says Ward. "In some cases, they vary from one year to hundreds of years to forever."On the other end of the spectrum, certain lifetime estimates seemed far too similar among the infographics. Of particular interest, Ward notes, were the estimates for how long fishing line lasts in the ocean. He says that all 37 infographics that included a lifetime for fishing line reported 600 years."Every single one said 600 years, it was incredible" he says. "I'm being a little tongue-in-cheek here, but we're all more likely to win the lottery than 37 independent science studies arriving at the same answer of 600 years for fishing line to degrade in the environment."In reality, these estimates didn't stem from actual scientific studies. Ward said he did a lot of digging to find peer-reviewed literature that was either funded, or conducted, by the agencies putting the information out there and couldn't find a single instance where the estimates originated from a scientific study. He and Reddy believe that while the information was likely well intentioned, the lack of traceable and documented science behind it was a red flag."The reality is that what the public and legislators know about the environmental persistence of plastic goods is often not based on solid science, despite the need for reliable information to form the foundation for a great many decisions, large and small," the scientists state in the paper.In one of their own peer-reviewed studies on the life expectancy of plastics published last year, Ward and his team found that polystyrene, one of the world's most ubiquitous plastics, may degrade in decades when exposed to sunlight, rather than thousands of years as previously thought. The discovery was made, in part, by working with researchers at WHOI's National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility to track the degradation of the plastic into gas and water phases, and with the aid of a specialized weathering chamber in Ward's lab. The chamber tested how environmental factors such as sunlight and temperature influenced the chemical breakdown of the polystyrene, the first type of plastic found in the coastal ocean by WHOI scientists nearly fifty years ago.Reddy feels that one of the biggest misconceptions surrounding the fate of plastics in the environment is that they simply break down in to smaller bits that hang around forever."This is the narrative we see all the time in the press and social media, and it's not a complete picture," says Reddy. "But through our own research and collaborating with others, we've determined that in addition to plastics breaking down into smaller fragments, they also degrade partially into different chemicals, and they break down completely into CO2." These newly identified breakdown products no longer resemble plastic and would be otherwise missed when scientists survey the oceans for missing plastics.Chelsea Rochman, a biologist at the University of Toronto who wasn't involved in the study, says that understanding the various forms of plastic degradation will be key to solving one of the enduring mysteries of plastic pollution: more than 99 percent of the plastic that should be detected in the ocean is missing."Researchers are beginning to talk about the global plastic cycle," says Rochman. "A key part of this will be understanding the persistence of plastics in nature. We know they break down into smaller and smaller pieces, but truly understanding mechanisms and transformation products are key parts of the puzzle."Overall, analyzing the infographics turned out to be an eye-opening exercise for the scientists, and unscored the importance of backing public information with sound science."The question of environmental persistence of plastics is not going to be easy to answer," says Ward. "But by bringing transparency to this environmental issue, we will help improve the quality of information available to all stakeholders -- consumers, scientists, and legislators -- to make informed, sustainable decisions."This research was funded by The Seaver Institute and internal funding from the WHOI Microplastics Catalyst Program.
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Geography
| 2,020 |
June 12, 2020
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https://www.sciencedaily.com/releases/2020/06/200612111414.htm
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Impacts of climate change on migrating mule deer
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When drought reshuffles the green-up of habitats that mule deer migrate across, it dramatically shortens the annual foraging bonanza they rely on.
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That is the main finding of a new University of Wyoming study, which shows the benefits of migration are likely to decrease for mule deer and other migratory herbivores as drought becomes more common due to ongoing climate change.Drought reduces the availability of key food resources by shortening the duration of spring green-up -- and altering the progression of the "green wave" across the landscape.The study was conducted by a team of researchers working with lead author Ellen Aikens, a 2019 graduate of the Wyoming Cooperative Fish and Wildlife Research Unit at UW. The paper was published this week in Global Change Biology, a leading journal documenting the biological effects of global change."This research shows that climate change can alter the underlying distribution of food resources by compressing the time when optimal forage is available, which reduces the benefit of migration," Aikens says. "This work highlights an emerging threat to migratory mule deer and likely many other migratory species."Aikens' analysis combined 19 years of drought data going back to 2001, with a 2013-15 GPS dataset of mule deer migrations in the Wyoming Range.In a wet year, the study found that mule deer have access to newly sprouted springtime plants during an extended period, up to 120 days. That's a full four months when snow is melting, and runoff is saturating the soil and causing forage plants such as sticky purple geranium to emerge.Deer get a significant portion of their forage benefit for the entire year by following this green wave of plants, which, in wet years, progresses in an orderly fashion from low-elevation winter ranges to summer ranges in the high mountains.Previous work by Aikens has shown that mule deer are experts at "surfing the green wave" across the landscape. Their movements allow them to always be in the right place at the right time to consume plants at their peak green-up, when they are protein-rich and easy to digest.Access to green-up provides mule deer their best chance to recover from harsh winters and to replenish lost body fat. They need sufficient fat to rear young and survive the coming winter.In dry years, the green wave sweeps across the landscape in about half the time, roughly 60 days, the researchers found.In essence, the good times don't last as long.Although deer surf these altered green waves as best they can, they only have half the time -- only two months -- to eat plants at peak forage quality.The researchers found that drought also makes for more patchy migration routes, where the green-up does not occur in sequence from low to high elevation. Patterns of green-up in dry years were quicker, less wave-like and, consequently, provided less of a foraging benefit to migrating mule deer.One thing that didn't change in drought years was the remarkable ability of deer to move and track plants at the highest nutritional value. Deer "surfed" right along with these same peak waves of plant growth in wet years and in dry years. Even in drought, there was no "trophic mismatch," a situation where migration timing is mismatched with food resources.Though researchers hoped to find that some migration routes were buffered from drought effects -- perhaps those that traverse shady north-facing slopes -- they found such routes did not exist. Instead, the best migration routes that produced the most abundant forage and the longest duration of green-up in wet years also were the most severely impacted by drought."This is a globally important study, because the findings ought to be relevant across the temperate landscapes of North America and Europe," says Matthew Kauffman, director of the Wyoming Cooperative Fish and Wildlife Research Unit and a co-author of the study."This study has revealed an underappreciated mechanism by which climate change is altering green-up and making migration less profitable for ungulates," Kauffman says. "We are identifying a new threat for migrating ungulates, which will likely worsen as climate change continues."
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Geography
| 2,020 |
June 11, 2020
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https://www.sciencedaily.com/releases/2020/06/200611183933.htm
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Half the earth relatively intact from global human influence
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Roughly half of Earth's ice-free land remains without significant human influence, according to a study from a team of international researchers led by the National Geographic Society and the University of California, Davis.
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The study, published in the journal "The encouraging takeaway from this study is that if we act quickly and decisively, there is a slim window in which we can still conserve roughly half of Earth's land in a relatively intact state," said lead author Jason Riggio, a postdoctoral scholar at the UC Davis Museum of Wildlife and Fish Biology.The study, published June 5 on World Environment Day, aims to inform the upcoming global Convention on Biological Diversity -- the Conference of Parties 15. The historic meeting was scheduled to occur in China this fall but was postponed due to the coronavirus pandemic. Among the meeting's goals is to establish specific, and higher, targets for land and water protection.Approximately 15 percent of the Earth's land surface and 10 percent of the oceans are currently protected in some form. However, led by organizations including Nature Needs Half and the Half-Earth Project, there have been bold global calls for governments to commit to protecting 30 percent of the land and water by 2030 and 50 percent by 2050.Intact natural lands across the globe can help purify air and water, recycle nutrients, enhance soil fertility and retention, pollinate plants, and break down waste products. The value of maintaining these vital ecosystem services to the human economy has been placed in the trillions of U.S. dollars annually.The coronavirus pandemic now shaking the globe illustrates the importance of maintaining natural lands to separate animal and human activity. The leading scientific evidence points to the likelihood that SARS-CoV2, the virus that causes the disease COVID-19, is a zoonotic virus that jumped from animals to humans. Ebola, bird flu and SARS are other diseases known to have spilled over into the human population from nonhuman animals."Human risk to diseases like COVID-19 could be reduced by halting the trade and sale of wildlife, and minimizing human intrusion into wild areas," said senior author Andrew Jacobson, professor of GIS and conservation at Catawba College in North Carolina.Jacobson said that regional and national land-use planning that identify and appropriately zone locations best suited to urban growth and agriculture could help control the spread of human development. Establishing protections for other landscapes, particularly those currently experiencing low human impacts, would also be beneficial.Among the largest low-impact areas are broad stretches of boreal forests and tundra across northern Asia and North America and vast deserts like the Sahara in Africa and the Australian Outback. These areas tend to be colder and/or drier and less fit for agriculture."Though human land uses are increasingly threatening Earth's remaining natural habitats, especially in warmer and more hospitable areas, nearly half of Earth still remains in areas without large-scale intensive use," said co-author Erle Ellis, professor of geography at the University of Maryland-Baltimore County.Areas having low human influence do not necessarily exclude people, livestock or sustainable management of resources. A balanced conservation response that addresses land sovereignty and weighs agriculture, settlement or other resource needs with the protection of ecosystem services and biodiversity is essential, the authors note."Achieving this balance will be necessary if we hope to meet ambitious conservation targets," said Riggio. "But our study optimistically shows that these targets are still within reach."
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Geography
| 2,020 |
June 11, 2020
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https://www.sciencedaily.com/releases/2020/06/200611152450.htm
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Plastic in the deep sea: Virtually unaltered after a quarter of a century
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Plastic products are durable. On one hand this is a great advantage, but on the other hand, if the plastic enters the environment, this advantage turns into a problem. According to current knowledge, natural degradation, as with organic matter, does not take place. It can only be estimated, how long plastic debris actually remains in the environment. Corresponding long-term experiments are lacking.
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This applies particularly to the deep sea that is only poorly explored itself. Plastic objects that are found by chance with the help of deep-sea robots or other underwater vehicles are difficult to date. However, during an expedition with the German research vessel SONNE in 2015, researchers from the GEOMAR Helmholtz Centre for Ocean Research Kiel, the Max Planck Institute for Marine Microbiology in Bremen and the Kiel University were able to recover several pieces of waste from the seabed of the Eastern Pacific Ocean in a depth of more than 4000 metre. Conducting a little detective work allowed to constrain the age of deposition quite accurately. For the first time, this offered the opportunity to conduct a long-term study on plastic degradation in the deep sea. The study was published today in the international journal In reality, in 2015 the team was out in the Pacific about 440 nautical miles (815 km) off the coast of Peru to investigate another long-term experiment in the so-called DISCOL area. There, German scientists had ploughed a piece of seafloor in 1989 in order to understand the environmental impacts arising from potential future mining of manganese nodules. They visited this site again in 1992, 1996 and in 2015 to study the recovery of the deep-sea ecosystem.In 2015, the remotely operated deep-sea robot ROV KIEL 6000 observed almost incidentally some waste and recovered it from the seafloor. Among it was a plastic bag containing a Coke can, which was part of a special edition produced for the Davis Cup 1988. "The aluminum can itself would have corroded in the deep sea, if it was not wrapped tightly inside a plastic garbage bag that preserved it. This also indicates that the garbage bag must be of the same age," says Dr. Matthias Haeckel from GEOMAR, project manager on board back then and now co-author of the study.A second recovered item was a curd box from a German manufacturer. The printed address shows a five-digit postal code. These were not introduced in Germany until 1990. However, the manufacturer was bought by a rival company in 1999, and the brand name disappeared."Since the DISCOL area is far away from important shipping routes, the plastic bag and the curd box could be attributed to the DISCOL expeditions in 1989 and 1992 or 1996," says Dr Haeckel. After all, this offered the extremely rare opportunity to examine in detail datable plastic objects from the deep sea. "It turned out that neither the bag nor the curd box showed signs of fragmentation or even degradation," says biochemist Dr. Stefan Krause from GEOMAR, lead author of the study. He led the onshore analyses in the home laboratories.A scientifically most interesting finding was that the microbial community on the plastic surfaces differed from the one identified in the surrounding seafloor sediments. "All of the species can be found in the deep-sea sediment, but apparently, larger accumulations of plastics could locally cause a shift in the ratio of the predominant species," says Dr. Krause.Overall, the study provides the first scientifically sound indication of the fate of plastic debris in the deep sea. "This study builds also an important basis for our new project HOTMIC, where we aim to trace the plastic waste entering the ocean from the continents to the large oceanic eddies and further to their final sink, the abyssal seafloor," says Dr Haeckel.At the same time, the findings provide a good argument for him to pay even closer attention to compliance with regulations regarding waste on board. "Fortunately, the mentality has changed considerably since the 1990s. Today, both, the crews of the ships and the research teams on board take great care to ensure that no waste is disposed overboard," says Dr Haeckel.
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Geography
| 2,020 |
June 11, 2020
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https://www.sciencedaily.com/releases/2020/06/200611114527.htm
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New insight into the Great Dying
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A new study shows for the first time that the collapse of terrestrial ecosystems during Earth's most deadly mass extinction event was directly responsible for disrupting ocean chemistry.
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The international study, led by the University of Leeds, highlights the importance of understanding the inter-connectedness of ecosystems as our modern environment struggles with the devastating effects of a rapidly warming planet.The Permian-Triassic extinction, also known as the Great Dying, took place roughly 252 million years ago. It saw the loss of an estimated 90% of marine species, 70% of land species, widespread loss of plant diversity and extreme soil erosion.While the exact cause of the terrestrial mass extinction is still debated, it is becoming apparent that the terrestrial ecosystems were wiped out prior to the marine ecosystems. However, until now it was unclear if or how the terrestrial extinction consequently impacted the chemistry of Earth's ancient oceans.The team built a computer model that mapped chemical changes in Earth's oceans during the period of the Permian-Triassic extinction. The model tracks the cycling of the poisonous element mercury, which is emitted from volcanoes but also gets incorporated into living organisms. By tracing both the mercury and carbon cycles, and comparing to measurements in ancient rocks, the team were able to separate out biological and volcanic events.This revealed that a massive collapse of terrestrial ecosystems cascaded organic matter, nutrients, and other biologically-important elements into the marine system.While further research is needed to understand the exact effect this had on marine life, the fact that many marine species rely on chemical stability in their environment means that it is unlikely it was without consequence.Study co-author Dr Jacopo Dal Corso, who conceived the study during a research placement at Leeds said: "In this study we show that during the Permian-Triassic transition, roughly. 252 million years ago, the widespread collapse of the terrestrial ecosystems caused sudden changes in marine chemistry."This likely played a central role in triggering the most severe known marine extinction in Earth's history. This deep-time example shows how important the terrestrial reservoir is in regulating global biogeochemical cycles and calls for the greater conservation of these ecosystems."Study co-author Dr Benjamin Mills, from the School of Earth and Environment at Leeds said: "252 million years ago the effects of mass plant death and soil oxidation appear to have seriously altered the chemistry of the oceans. This is an uncomfortable parallel with our own human-driven land use change, and we too are transferring large quantities of nutrients and other chemicals to the oceans."As we look to re-start the world's economies in the wake of the current pandemic, protecting our life-sustaining ecosystems should be a priority."
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Geography
| 2,020 |
June 11, 2020
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https://www.sciencedaily.com/releases/2020/06/200611104802.htm
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Protecting eels protects freshwater biodiversity
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An international research team has conducted a field survey on two species of eel native to Japan and other organisms that share the same habitat, revealing for the first time in the world that these eels can act as comprehensive surrogate species for biodiversity conservation in freshwater rivers. It is hoped that conducting activities to restore and protect eel populations will contribute greatly to the recovery and conservation of freshwater ecosystems that have suffered a significant loss of biodiversity.
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The team consisted of Researcher ITAKURA Hikaru (of Kobe University's Graduate School of Science, and a JSPS Overseas Research Fellow at the University of Maryland), Specially Appointed Researcher WAKIYA Ryoshiro (of The University of Tokyo), Dr. Matthew Gollock (of The Zoological Society of London) and Associate Professor KAIFU Kenzo (Chuo University).The results of this research were published in the British scientific journal 'Although freshwater covers only 2.3% of the Earth's surface, it provides diverse habitats that support a far greater number of species per area than terrestrial or marine ecosystems. However, at the same time freshwater ecosystems have suffered significant deterioration and loss of biodiversity due to the human populations concentrated around them. As a result far more freshwater species are in danger of extinction than species belonging to other ecosystems. One third of freshwater species have been classified as 'Endangered' in the International Union for Conservation of Nature (IUCN)'s Red List of Threatened Species.It is challenging to monitor and manage all the species that make up these ecosystems in order to protect biodiversity. For this reason, it is thought that by focusing conservation efforts on one or a few species, we can understand the functions, resource dynamics and structures of the biological communities to which they belong. This knowledge can be used to manage and conserve biodiversity. These surrogate species are classified as umbrella, indicator or flagship species according to conservation goals. So far some large mammal and bird species have been proposed as surrogate species.The two kinds of eel that were the subject of this study are catadromous, meaning that they are migratory species that spawn in the ocean and grow in rivers and coastal waters. Anguillid eels can be found almost worldwide (except for the polar areas); in the varied aquatic environments of 150 countries, including inner bays, and all parts of rivers from the source to mouth.In this study, the researchers focused on the eels' unique life cycle and confirmed that they can serve as umbrella, indicator and flagship species. They propose that eels are a comprehensive surrogate species for the conservation of freshwater biodiversity.Eel and other freshwater organisms (fish and large crustaceans such as crab and shrimp) were collected from 78 sites spanning upstream to downstream regions in six rivers in Japan using an electric shocker (three mainland rivers in Kyushu and Honshu, and three rivers on Amami-Oshima island). The Japanese eel is mostly found in the mainland rivers, whereas the giant mottled eel largely inhabits Amami-Oshima's rivers. In order to determine these two species' suitability as indicator and umbrella species for biodiversity conservation, the distribution of the sampled eels and freshwater organisms in the rivers was analyzed and their trophic levels in the food web were researched. Furthermore, the researchers also investigated the quantitative relationship between the number of eels and the number of other migratory diadromous species (biodiversity), and the environmental factors affecting this. Japan is a mountainous country and there are many small, fast flowing rivers. It was predicted that the migratory species that travel between the sea and the rivers during their life cycles would be predominant in freshwater rivers' ecosystems. Therefore, a large number of migratory species was interpreted as an indicator of biodiversity.The results from each of the field studies on Japanese eels and giant mottled eels showed that they were the most widely distributed of all freshwater species in river habitats. Japanese eels covered 87% of the study rivers in mainland Japan, whereas the giant mottled eel was found in 94% of the Amami Oshima rivers used in this study. Stable isotope analyses of the muscle tissue of eel and other freshwater organisms were carried out to estimate their trophic levels. The results showed that the mean trophic levels of eel species were greater than three which indicates that they are higher-order predators, and these values were significantly higher than those for other freshwater organisms. These results support the eels' potential as umbrella species and show that they require a diverse range of lower trophic level animals for food.This study confirmed the presence of 48 species of freshwater organisms, including fish and crustaceans. As predicted, a total of 80% of these were migratory species (78% in Honshu/Kyushu and 91% on Amami Oshima island). Furthermore, there was a positive correlation between the number of Japanese eels or giant mottled eels and the number of other migratory species. A statistical model was used to investigate various environmental factors that may have an impact on both of these groups. The researchers found a strong negative correlation between the number of eels and other migratory species and the following two points; 'the distance of the study site from the sea' and the 'cumulative height of trans-river structures, such as dams or weirs, that species have to pass in order to get from the sea to the study site'. These factors have an impact on river-ocean connectivity for migratory species. In other words, these results imply that the positive correlation found between the number of eels and the number of other migratory species is probably an indirect relationship through river-ocean connectivity. In areas where river-ocean connectivity is high (i.e., it's easy for them to swim upstream), there will be greater numbers of eels and other migratory species. Conversely, if river-ocean connectivity is low, there will be fewer of these species. These results show that eels are an indicator of good river-ocean connectivity, and through this they are an indicator of biodiversity.This research showed that trans-river structures have a negative impact on eels and other migratory species. It has been indicated that eels can climb such structures vertically, if the structures are wet. However, trans-river structures inhibit eel movement, moreover they have been shown to cause a decline in the numbers of many eel species. In this study, it was shown that even barriers under 1m high could have a negative impact on eel distribution. Previous studies have indicated that the habitat loss caused by these trans-river structures is a leading factor in the decline in eel numbers. Many other studies have reported that the distribution of other migratory species is limited by these structures in a similar way to eels. Eels are an indicator of river-ocean connectivity. It is hoped that improving and maintaining this connectivity for eels will greatly boost the biodiversity of freshwater ecosystems.In 2016, IUCN decided upon the 'Promotion of Anguillid eels as flagship species for aquatic conservation'. This designation was based on the widespread decline of eel numbers, the effects of habitat deterioration and destruction, as well as eels' global distribution and their unique catadromous migration. As shown in this study, eels have the following important aspects that make them suitable as a flagship species; they are widely distributed, higher-order predators that are generally larger than other freshwater organisms, and are easily identifiable.Looking at eels in terms of their importance ecologically, commercially and culturally, we can conclude that they have provided a diverse ecological service worldwide since ancient times. Eels are found almost all over the world, and have served as a source of food in various lands and eras. They have played roles in food cultures, in literature and art, in legends and belief systems. Therefore, the researchers concluded that eels have the ability to stir up great public awareness worldwide about environmental issues, which is connected to their value as a flagship species.In conclusion, eels can serve as indicator, umbrella and flagship species, making them a comprehensive surrogate for the conservation of freshwater biodiversity.This study confirmed the possibility that eels could be used as a surrogate species by using Japanese rivers as a model. These results could be applied to regions where, like in Japan, migratory species dominate freshwater ecosystems, such as islands that are relatively new geologically. On the other hand, continental freshwater ecosystems, for example, have a higher diversity of primary freshwater species that spend their entire lives in freshwater compared to Japan, therefore it is predicted that the impact of river-ocean connectivity on biodiversity would be lower than in the results of this study. However, trans-river structures also inhibit the mobility of primary freshwater species, such as upriver migrations for egg laying.Sixteen species of eel have been discovered so far and they are globally distributed. Consequently, eels have the potential to be a surrogate species for freshwater biodiversity conservation worldwide, due to their importance in ecosystems as widely distributed higher-order predators, in addition to their commercial and cultural importance. It is hoped that further research could investigate this possibility in continental rivers and elsewhere.*1. Umbrella, indicator and flagship species:Umbrella species: Conserving an umbrella species enables the conservation of many other species in that biological community. This method is often applied to species that are widely distributed or are higher-order predators.Indicator Species: A species that enables factors such as human impact, habitat changes, biodiversity and the resource dynamics of other species to be evaluated.Flagship species: A species that is used to promote conservation planning and cooperation in the face of environmental issues in a particular area, country or on a global scale, with the aim of achieving successful results. Popular, appealing and familiar species are often chosen for these measures; they are usually higher-order predators (for example, large mammal or bird species) that are in danger of becoming extinct.*2. Stable isotope analysis:Isotopes of a chemical element have the same number of protons but a different number of neutrons in each atom. Isotopes that remain unchanged are called stable isotopes. Of the elements in organisms' compositions, the stable isotopes of nitrogen and carbon are often used when researching food-web structure. Since stable nitrogen isotopes vary depending on the consumed and the consumer, they show the target organism's trophic level in the food web.This study was conducted with support from the Environmental Research Fund by the Japanese Ministry of the Environment, and the Japanese eel research project by the Fisheries Agency of Japan.
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Geography
| 2,020 |
June 11, 2020
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https://www.sciencedaily.com/releases/2020/06/200611094134.htm
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Could we run out of sand? Scientists adjust how grains are measured
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Humans see sand as an infinite resource. We are astounded to discover there are more stars in the universe than grains of sand on our beaches.
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Yet in some areas, sand is in short supply and scientists have discovered the way we keep track of this resource has given us misleading information.In many instances, we have simply been measuring sand the wrong way."Not all sand is the same," said Associate Professor Ana Vila-Concejo from the University of Sydney School of Geosciences. "Yet the models for assessing sand and how it moves mostly rely on one type. This means we have an inaccurate picture of what is happening, especially in coastal areas that are vulnerable to climate change."Dr Amin Riazi from Eastern Mediterranean University worked with Associate Professor Vila-Concejo during a short stay at the University of Sydney to develop new engineering models that account for the different shapes of sand grains. Standard models assume sand grains are spherical, which is fine for common sands made up of ground-down silica and quartz rocks.However, carbonate sands derived from shells, corals and the skeletons of marine animals tend to be elliptical, less dense and have more holes and edges. The new research has taken this into account with astounding results, finding that existing models underestimate the surface area of carbonate sands by 35 percent.Published today in the "This means we are not accounting for sand correctly," she said. "While this has impact on construction and manufacturing, it could also have a big effect on the management of coastal areas impacted by climate change."Sand is used throughout industry. From the glass in your mobile phone to base for roads, sand is used across our economy. In fact, sand and gravel are the most extracted materials on the planet, exceeding that of fossil fuels.Associate Professor Vila-Concejo said: "While sand wars are not happening in Australia, we do have areas with chronic coastal erosion and sand loss such as at Jimmys Beach in Port Stephens."Her team took carbonate sand from near Heron Island on the Great Barrier Reef and observed how it responded under experimental conditions. Based on these observations, they developed new mathematical equations that much better predict how carbonate sands move.The team confirmed this by applying their equations to existing data on carbonate sand movement accumulated over six years from observations off the north coast of Oahu, Hawaii."Keeping track of carbonate sand will become increasingly important," said Dr Tristan Salles, also from the School of Geosciences in the Faculty of Science."If islands and atolls are at risk from erosion caused by sea-level rise, it will be vital to understand how the sands protecting them will respond to the ocean currents, waves and high-energy sea swells battering them."He said these new equations are likely to be used to update all sediment transport models. "This will include evaluating beach and atoll responses to ocean hydrodynamics in carbonate-sand-rich regions, some of which are most vulnerable to the impacts of climate change," Dr Salles said.At present, coastal engineering uses models based on siliciclastic sands. Associate Professor Vila-Concejo hopes that the models her team has developed can be used to improve management of coastal areas."This means we can develop a far more accurate picture of how changing oceans will affect marine ecosystems where carbonate sands are dominant," Associate Professor Vila-Concejo said."Understanding how, why and when sediments move is crucial to managing and predicting the effects of climate change and our new work will help in the development of mitigation and adaptation strategies."
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Geography
| 2,020 |
June 10, 2020
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https://www.sciencedaily.com/releases/2020/06/200610152015.htm
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Island 'drowning' is not inevitable as sea levels rise
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Coral reef islands across the world could naturally adapt to survive the impact of rising sea levels, according to new research.
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The increased flooding caused by the changing global climate has been predicted to render such communities -- where sandy or gravel islands sit on top of coral reef platforms -- uninhabitable within decades.However, an international study led by the University of Plymouth (UK) suggests that perceived fate is far from a foregone conclusion.The research, published in The results show that islands composed of gravel material can evolve in the face of overtopping waves, with sediment from the beach face being transferred to the island's surface.This means the island's crest is being raised as sea level rises, with scientists saying such natural adaptation may provide an alternative future that can potentially support near-term habitability, albeit with additional management challenges, possibly involving sediment nourishment, mobile infrastructure and flood-proof housing.The research was led by Gerd Masselink, Professor of Coastal Geomorphology in Plymouth, working with colleagues at the University of Auckland (New Zealand) and Simon Fraser University (Canada).Professor Masselink, who heads Plymouth's Coastal Processes Research Group, said: "In the face of climate change and sea level rise, coral reef islands are among the most vulnerable coastal environments on the planet. Previous research into the future habitability of these islands typically considers them inert structures unable to adjust to rising sea level. Invariably, these studies predict significantly increased risk of coastal flooding and island inundation, and the concept of 'island loss' has become entrenched in discourses regarding the future of coral reef island communities. In turn, this has led to attention being focused on either building structural coastal defences or the exodus of island communities, with limited consideration of alternative adaptation strategies."It is important to realise that these coral reef islands have developed over hundreds to thousands of years as a result of energetic wave conditions removing material from the reef structure and depositing the material towards the back of reef platforms, thereby creating islands. The height of their surface is actually determined by the most energetic wave conditions, therefore overtopping, flooding and island inundation are necessary, albeit inconvenient and sometime hazardous, processes required for island maintenance."Co-author Professor Paul Kench, currently Dean of Science at Simon Fraser University, Canada, said: "The model provides a step-change in our ability to simulate future island responses to sea level rise and better resolve what the on-ground transformations will look like for island communities. Importantly, our results suggest that island drowning within the next few decades is not universally inevitable. Understanding how islands will physically change due to sea level rise provides alternative options for island communities to deal with the consequences of climate change. It is important to stress there is no one-size-fits-all strategy that will be viable for all island communities -- but neither are all islands doomed."For the research, scientists created a scale model of Fatato Island, part of the Funafuti Atoll in Tuvalu, and placed it in the Coastal Ocean and Sediment Transport (COAST) Lab at the University of Plymouth.It was then subjected to a series of experiments designed to simulate predicted sea level rises with the results showing that the island's crest rose with the rising sea level, while retreating inland, as a result of water overwashing the island and depositing sediment on the island's surface.A numerical model was validated using these laboratory experiments, and three numerical modelling scenarios were then used to assess how the island adjusted to a sea level rise of 0.75m, the global average increase predicted for 2100 by the Intergovernmental Panel on Climate Change.During the numerical simulations, the island crest rose by just under 0.7m, showing that islands can keep up with rising level and confirming the laboratory experiments, although the precise future rate of sea level rise will be critical in determining their future.
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June 10, 2020
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https://www.sciencedaily.com/releases/2020/06/200610152009.htm
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Bedrock type under forests greatly affects tree growth, species, carbon storage
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A forest's ability to store carbon depends significantly on the bedrock beneath, according to Penn State researchers who studied forest productivity, composition and associated physical characteristics of rocks in the Appalachian ridge and Valley Region of Pennsylvania.
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The results have implications for forest management, researchers suggest, because forests growing on shale bedrock store 25% more live, aboveground carbon and grow faster, taking up about 55% more carbon each year than forests growing on sandstone bedrock.The findings demonstrate that forests underlain by shale in this region provide more ecosystem services such as carbon uptake and biodiversity, explained researcher Margot Kaye, associate professor of forest ecology in the College of Agricultural Sciences. Also, shale forests make up a smaller portion of the landscape and should be high-priority candidates for management or conservation."As forests grow and respond to warming, shifts in precipitation and invasive species, managers will benefit from incorporating lithological influences and considerations on forest composition and productivity," she said. "For example, conserving forests growing on shale with higher species diversity will likely lead to forests that are resilient to stressors and can grow more vigorously."Forest managers -- now realizing the disparity of productivity -- may target forests growing over shale for conservation and carbon sequestration, Kay contends. In contrast, they may decide that forests growing over sandstone are better suited for wildlife habitat management or recreation.To reach their conclusions, researchers analyzed forest inventory data from 565 plots on state forest and game lands managed by the Pennsylvania Department of Conservation and Natural Resources and the state Game Commission in the Appalachian Ridge and Valley Region. They used a suite of GIS-derived landscape metrics, including measures of climate, topography and soil physical properties, to identify drivers of live forest carbon dynamics in relation to bedrock.Those forest plots contained more than 23,000 trees, ranging from 20 to 200 years old, with most being 81 to 120 years old, according to the most recent available forest inventory data. In the study dataset, 381 plots were on sandstone bedrock and 184 were on shale -- a similar ratio to the amount of Pennsylvania public land on each bedrock type in the Ridge and Valley Region. There are 812,964 acres of forest on sandstone and 262,025 acres of forest on shale in the region."That is an eye-opening number," said lead researcher Warren Reed, a doctoral student in ecology.While forests underlain by both shale and sandstone bedrock were oak dominated, the tree communities are quite different, Reed pointed out. Northern red oak is more dominant on shale bedrock, and chestnut oak dominates on sandstone. Most species in the forest tend to be more productive on shale, and the diversity of tree species is higher in sites on shale bedrock.Forests grow faster over shale bedrock than sandstone bedrock because of soil characteristics that generally make water more available to trees, Reed hypothesized. Over millions of years, bedrock breaks down, becomes parent material and soils develop. Because of the composition of the rock types, shales break down into soils with finer texture than sandstone, which is coarser.Forests above shale bedrock growing in finer soils typically have better access to water during the growing season."We see this across the landscape, so forest productivity is indirectly related to bedrock," Reed said. "Oaks growing on sandstone are more sensitive to annual climate and water availability -- or put differently, oak growth on sandstone is more limited by water than on shale."The findings of the research, recently published in The concept of geologic influences on forest growth will be especially valuable in Pennsylvania, Reed said, because it is a major producer of hardwood lumber, and the state has so much forest growing on its portion of the Appalachian Ridge and Valley Region. The Ridge and Valley is a major portion of the forested Appalachian Mountains, so these rules should apply from southern New York to northern Georgia within that landscape."Sequestering carbon in forests is one of the many nature-based solutions we have to combat global climate change," he said. "I believe this is an ecosystem service that will continue to gain traction and eventually greater market value."The National Science Foundation and the U.S. Department of Agriculture's National Institute of Food and Agriculture supported this research.
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Geography
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June 10, 2020
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https://www.sciencedaily.com/releases/2020/06/200610121004.htm
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Extinct camelids reveal insights about North America's ancient savannas
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A new study looking at extinct camelids -- ancestors of today's camels and llamas -- tells the story of North America's ancient savannas and highlights how past climatic and environmental conditions influenced the composition of mammalian faunas.
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Although savanna habitats (treed grasslands) are only found in the tropics today, around 18 million years ago, during the Miocene epoch, savanna ecosystems, similar to those of modern Africa, existed in the mid latitudes of North America. At their peak -- around 12 million years ago -- they were comparable in their mammalian diversity to that of the Serengeti today.The study, published in Lead author of the research, Nuria Melisa Morales García from the University of Bristol, said: "The North American savannas housed a vast diversity of camelids. In fact, camelids actually originated and first diversified in North America where they lived for more than 40 million years and were incredibly successful and widespread."The researchers measured the skulls, jaws and limb bones of dozens of extinct North American artiodactyls, including camelids, and compared them with those living today in the Serengeti savanna of East Africa. The researchers recorded data on body size and on aspects of the anatomy of the animals that are linked with their ecology."The Serengeti mammals are very well known to research: we know how they live, how they eat and we have all their measurements. By using what we know about them, we can make solid inferences on how the extinct artiodactyls of North America were behaving," said Professor Christine Janis, from the University of Bristol's School of Earth Sciences and supervising author of the study.The analysis showed that while there was considerable overlap between the ecologies of extinct and modern species, the majority of extinct camelids were most similar to the modern common eland, an arid-adapted antelope with a diet of grass and leaves. This reveals important information about the ecosystem they inhabited and suggests the North American savannas were drier than modern African savannas (a notion supported by other research)."We also studied how these faunas were affected by the climatic changes of the Neogene: as temperatures dropped and conditions became more arid, these faunas became more depauperate -- lacking in number and diversity. Camels still dominated in these faunas, but the diversity of all ungulates took a big hit. Our study shows how ungulate faunas responded to a particular scenario of climate change which, now more than ever, is extremely relevant in understanding what is to come," said Morales-García.
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Geography
| 2,020 |
June 10, 2020
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https://www.sciencedaily.com/releases/2020/06/200610102723.htm
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Antarctic sea-ice models improve for the next IPCC report
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The world of climate modeling is complex, requiring an enormous amount of coordination and collaboration to produce. Models feed on mountains of different inputs to run simulations of what a future world might look like, and can be so big -- in some cases, lines of code in the millions -- they take days or weeks to run. Building these models can be challenging, but getting them right is critical for us to see where climate change is taking us, and importantly, what we might do about it.
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A study in All the models projected decreases in the aerial coverage of Antarctic sea ice over the 21st century under different greenhouse gas emission scenarios, but the amount of loss varied considerably between the emissions scenarios."I am really fascinated by Antarctic sea ice, which the models have struggled more with than Arctic sea ice," said lead author Lettie Roach, a postdoctoral researcher at the University of Washington. "Not as many people are living near the Antarctic and there haven't been as many measurements made in the Antarctic, making it hard to understand the recent changes in sea ice that we've observed through satellites."The models are known as coupled climate models, meaning they incorporate atmospheric, ocean, terrestrial and sea ice models to project what the future holds for our climate system. We are all familiar with the story of soon-to-be ice-free summers in the Arctic and the implications that may have on global trade. But what's driving change around Antarctic sea ice and what's expected in the future is less clear.This study's assessment of Antarctic sea ice in the new climate models is among the first."This project arose from a couple of workshops that were polar climate centered, but no one was leading an Antarctic sea ice group," said Roach. "I put my hand up and said I would do it. The opportunity to lead something like this was fun, and I'm grateful to collaborators across many institutions for co-creating this work."The Antarctic is characterized by extremes. The highest winds, largest glaciers and fastest ocean currents are all found there, and getting a handle on Antarctic sea ice, which annually grows and shrinks six-fold, is critically important. To put that into perspective, that area is roughly the size of Russia.The icy parts of our planet -- known as the cryosphere -- have an enormous effect on regulating the global climate. By improving the simulation of Antarctic sea ice in models, scientists can increase their understanding of the climate system globally and how it will change over time. Better sea ice models also shed light on dynamics at play in the Southern Ocean surrounding Antarctica, which is a major component of our southern hemisphere."The previous generation of models was released around 2012," says Roach. "We've been looking at all the new models released, and we are seeing improvements overall. The new simulations compare better to observations than we have seen before. There is a tightening up of model projections between this generation and the previous, and that is very good news."
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Geography
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June 9, 2020
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https://www.sciencedaily.com/releases/2020/06/200609130020.htm
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Study on shorebirds suggests that when conserving species, not all land is equal
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Princeton University researchers may have solved a long-standing mystery in conservation that could influence how natural lands are designated for the preservation of endangered species.
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Around the world, the migratory shorebirds that are a conspicuous feature of coastal habitats are losing access to the tidal flats -- the areas between dry land and the sea -- they rely on for food as they travel and prepare to breed. But a major puzzle has been that species' populations are plummeting several times faster than the rate at which coastal ecosystems are lost to development.Nowhere is the loss of tidal flats and shorebird species more acute than along the East Asia-Australasian Flyway (EAAF). An estimated 5 million migratory birds from 55 species use the flyway to travel from southern Australia to northern Siberia along the rapidly developing coast of China -- where tidal flats can be more than 6 miles wide -- at which birds stop to rest and refuel.Since the 1980s, the loss of tidal flats around the Yellow Sea has averaged 1.2% per year. Yet, the annual loss of the most endangered bird species has averaged between 5.1 and 7.5%, with populations of species such as the critically endangered spoon-billed sandpipers (Calidris pygmaea) climbing as high as 26% each year.In exploring this disparity, Princeton researchers Tong Mu and David Wilcove found a possible answer -- the birds don't use all parts of the tidal flat equally. They discovered that migratory shorebirds overwhelmingly rely on the upper tidal flats closest to dry land, which are the exact locations most often lost to development.They report in the journal The findings stress the need for integrating upper tidal flats into conservation plans focused on migratory shorebirds, the authors reported."This is a new insight into Asian shorebirds, but I suspect that the upper intertidal is disproportionately important to shorebirds in other places, too, such as the East and West coasts of North America," said Wilcove, who is a professor of ecology and evolutionary biology and public affairs and the Princeton Environmental Institute (PEI)."People start at the upper zone and work their way outward, so the best spots for the birds are the first to go," he said. "It would probably be best to extend current developments farther into the intertidal zone rather than keep building parallel to the coast, which consumes more of the upper intertidal."Think of it as advocating for a rectangle with the long side pointing into the sea versus a rectangle with the long side hugging the shore," Wilcove said.The study results also suggest that protecting species and their habitats may mean more than designating land for wildlife -- it may require identifying the right land to set aside by gaining a detailed understanding of exactly how animals interact with the landscape."Recognizing the importance of a kind of habitat to specific species or groups of species takes time, effort and thought," said Mu, who is the paper's first author and a Ph.D. candidate in ecology and evolutionary biology."Sometimes we just don't know what to look for, or looking requires challenging some prevalent and maybe false perceptions," he said. "But the situation is getting better and better. People are paying more attention to environmental issues, and the advances in technology are helping us gain more and newer insight into these questions."Mu conducted fieldwork between September 2016 and May 2017 at two well-known stopover sites -- one outside of Beijing, the other near Shanghai -- for migratory shorebirds in the Yellow Sea region. He focused on 17 species of birds, noting where along the tidal flat the animals preferred to feed.A key difference to his approach, Mu said, is that most previous research focused on the low-tide period when all the tidal flats are exposed and the full range of intertidal species can be observed."It makes sense from an ecological point of view. During the high tides when only a portion of the tidal flats is accessible, the relationship usually still holds for the exposed area," Mu said. "So, there's little incentive to look at the periods other than low tide when researchers can get a more complete picture."What Mu thinks was missed, however, was that the upper tidal flats provide the most amount of foraging time for birds that have places to be. Even if the lower half of a 6-mile wide mudflat is set aside for migratory birds, they're not getting the energy they need for the trip ahead during the high tide, he said."The value of the tidal flats comes from not only their size, but also how much foraging time they can provide," Mu said. "The upper tidal area is exposed for a longer period during tidal cycles, compared to the middle and lower areas, which I think permits shorebirds to forage for a longer time and thus get more energy."The preservation of shorebirds should be driven by how integral the animals are to the health of intertidal zones, Mu and Wilcove said. In turn, tidal flats are not only vital to other marine life, but also provide people with seafood such as clams and crabs and protection from storms and storm surges that cause coastal flooding."Shorebirds facilitate the energy and nutrient exchanges between land and sea," Mu said. "Because a lot of them are long-distance migrants, they also facilitate the energy and nutrient exchanges across different ecosystems and continents, something that is usually overlooked and underappreciated."Wilcove and Mu cited recent research showing that more than 15%, or more than 12,000 square miles, of the world's natural tidal flats were lost between 1984-2016."Some of the greatest travelers on Earth are the shorebirds that migrate from Siberia to Southeast Asia and Australia," Wilcove said. "Now, they're declining in response to the loss of the tidal areas, and the full range of benefits those tidal flats provide are in some way being diminished."
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Geography
| 2,020 |
June 9, 2020
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https://www.sciencedaily.com/releases/2020/06/200609095042.htm
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Scientists lament 'Humpty Dumpty' effect on world's spectacular, rare wildlife
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Some of the world's largest, most spectacular and unheralded mammals are silently slipping away, species like Tibetan wild yaks and Patagonia's huemul, Bhutan's takin and Vietnam's saola. Even Africa's three species of zebras and wildebeest have suffered massive reductions over the last several decades.
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The reasons for these losses are more than disease and habitat fragmentation, deforestation or wildlife trade, according to researchers. Ultimately, the cause is rampant human population growth. And unless human behavior changes in unprecedented ways, these scientists warn that future communities of these mammals will never resemble those of the recent past or even today.The findings are based on a new study, "Disassembled food webs and messy projections: modern ungulate communities in the face of unabating human population growth," published June 9 in Joel Berger, lead author of the study and a professor at Colorado State University, said that the time for action is now, and that touting past conservation achievements does little to better humanity's future."We all must realize we're members of a broad, beautiful and living planet, and we must find ways to subsist in this together or suffer more severe consequences than what we already see," said Berger, also a senior scientist at the Wildlife Conservation Society (WCS). "For many assemblages of animals, we are nearing a moment in time, when, like Humpty Dumpty, we will not be able to put things back together again." Berger is also the Barbara Cox Anthony University Chair of Wildlife Conservation at CSU.In this study, the research team -- which also included Alejandro Vila, the director for Science for WCS's Patagonia Program; Cristobal Briceno, a professor and veterinarian at University of Chile; and Joanna Lambert, a professor at the University of Colorado Boulder -- analyzed direct and indirect disruptions that lead to the changing roles of mammals in global ecosystems and noted how the nature of ecological interactions has changed and will do so, on an even larger scale, in coming decades.More specifically, they looked at what has transpired with the huemul in Patagonia, takin in Bhutan, wild horses in deserts, wolves and coyotes in North America, and the inevitability of change in big ecosystems as large carnivores are extirpated.Scientists said this is happening as the human population increases it footprint on land."Even in the remote reaches of the Himalayas, stray and feral dogs, a direct result of human intrusions, wreak havoc on wild and domestic species of high economic value and cultural importance," said Tshewang Wangchuk, a study co-author, conservation biologist and president of the Bhutan Foundation.Humans only recently colonized parts of the Himalayas, areas where ice has receded due to warming temperatures. Yet, the authors also point to human population change at a global scale. In 1830 when Vice-Admiral Robert Fitzroy captained his ship, the Beagle, through the Magellan Straits of South America, fewer than 1.2 billion people inhabited Earth. By Earth Day in 1970, there were more than 3.5 billion.Today, only 50 years later the world's population approaches eight billion. Livestock and humans now constitute a staggering 97 percent of the planet's mammal biomass.The research team said worldwide food webs have become irretrievably altered by humans, with little hope to reconstitute even recent past conditions or to put back the ecological functions once created by native species.Feral pigs, for instance, exist today on every continent except Antarctica, and in 70 percent of the states in the United States. These animals disrupt fish, reptiles, birds and other small mammals, plants and soils. In addition, climate change warms the oceans, which in turn foments marine algal blooms, reducing fishery catches. With less demand for fish, a consequent uptick in wildlife poaching on land occurs.The scientists also documented how an appetite for fashion like cashmere increases imports to the west from Mongolia, India and China, resulting in economic incentives for desert pastoralists to produce more domestic goats in central Asia. These goats compete for food with native species and are in danger due to increasing numbers of dogs in these areas. The dogs are not only predators but also carry diseases, which jeopardizes endangered species like snow leopards, kiang and Przewalksi's gazelle.Berger and the study authors suggest that despite the grim findings, all is not yet lost.The world has remarkable protected areas including: Serengeti and Kruger National Park in Africa, Yellowstone and Wrangell-St. Elias National Park & Preserve in North America, Madidi National Park in Bolivia, the Patagonia Ice Fields of Chile and Argentina, Chang Tang Nature Reserve in China, and Northeast Greenland National Park, the world's largest national park.And although food webs with large mammals will be different from those of the past and operate differently today, there are options to shape the future."It is not too late and we simply do not have the luxury of time to mourn what we have lost," said Lambert. "We need to use our ecological grief to implement action and honor the exceptional biodiversity that remains. This can be done by protecting large tracts of the planet's wild places."
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Geography
| 2,020 |
June 9, 2020
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https://www.sciencedaily.com/releases/2020/06/200609095102.htm
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California's climate refugia: Mapping the stable places
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Some landscapes can hold their own against climate change better than others.A studyfrom the University of California, Davis, maps these places, called "climate refugia," where existing vegetation is most likely to buffer the impacts of climate change through the end of the century.
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It found that about 15 percent of natural lands in California serve as climate refugia for the state's plants, including trees, shrubs, annuals and perennials. The mapping tool can help natural resource managers prioritize and plan climate-adaptive management efforts, such as wildlife habitat conservation and post-wildfire restoration.The study is published in a special issue of the journal As climate change intensifies, identifying and mapping areas of relative stability -- what the journal calls the "slow lane" for climate change -- marks a path toward conserving them and the habitat and services they provide to wildlife and humans."This paper shows that there are places where, if you retain what's standing there now, it would have a better chance of remaining for a longer period of time -- like a century -- under wetter and drier conditions," said lead author James Thorne, a research scientist with the UC Davis Department of Environmental Science and Policy.The northwest Klamath Mountains, northern Sierra Nevada and the Central Coast ranges contain large areas where existing vegetation types are expected to persist under both wetter and drier future climate conditions. These areas are called "consensus refugia."The three forest types occupying consensus refugia across large parts of Northern California include Klamath mixed conifer, Sierra mixed conifer and Douglas fir. Grasslands and coastal sage scrub cover much of the refugia in the Central Coast ranges.Vegetation with the largest portions (more than 50 percent) of their extent in climate refugia include montane chaparral and Klamath mixed conifer forests. A quarter of existing Douglas fir also occurs in consensus refugia.Other findings:- Elevation and latitude matter: Blue oak woodland and blue oak-foothill pine occurred less in consensus refugia than oaks at higher elevations.-Iconic coast redwood forests (0.4 percent of its current range), coast live oak woodland (3.8 percent) and red fir forests (2.3 percent) were poorly represented within the consensus refugia.If only 15 percent of California's natural lands have climate refugia characteristics for both a wetter and drier future, what does that mean for the remaining 85 percent? Thorne explains that it doesn't mean all other plants and trees will be outright destroyed. But they will likely face a higher level of climate stress than vegetation in refugia. Stress can affect rates of regeneration, reproduction and resilience under warming temperatures, drought, flood and fire.Previous work by Thorne modeled climate risk to California's native vegetation under various emissions-saving scenarios and found that half the state's native vegetation is at risk for climatic stress. This new paper assumes a business-as-usual climate scenario under which greenhouse gas emissions continue their current trajectory."California is one of the biodiversity hot spots of the world," Thorne said. "Our natural ecosystems help to support all of the people in the state as well as this incredible range of species. My hope is that we start to be proactive in our management of landscapes, understanding that climate change is going to bring impacts and that we have to change how we address them."
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Geography
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June 8, 2020
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https://www.sciencedaily.com/releases/2020/06/200608192523.htm
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Entire Roman city revealed without any digging
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For the first time, archaeologists have succeeded in mapping a complete Roman city, Falerii Novi in Italy, using advanced ground penetrating radar (GPR), allowing them to reveal astonishing details while it remains deep underground. The technology could revolutionise our understanding of ancient settlements.
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The team, from the University of Cambridge and Ghent University, has discovered a bath complex, market, temple, a public monument unlike anything seen before, and even the city's sprawling network of water pipes. By looking at different depths, the archaeologists can now study how the town evolved over hundreds of years.The research, published today in GPR works like regular radar, bouncing radio waves off objects and using the 'echo' to build up a picture at different depths.* By towing their GPR instruments behind a quad bike, the archaeologists surveyed all 30.5 hectares within the city's walls -- Falerii Novi was just under half the size of Pompeii -- taking a reading every 12.5cm.Located 50 km north of Rome and first occupied in 241 BC, Falerii Novi survived into the medieval period (until around AD 700). The team's GPR data can now start to reveal some of the physical changes experienced by the city in this time. They have already found evidence of stone robbing.The study also challenges certain assumptions about Roman urban design, showing that Falerii Novi's layout was less standardised than many other well-studied towns, like Pompeii. The temple, market building and bath complex discovered by the team are also more architecturally elaborate than would usually be expected in a small city.In a southern district, just within the city's walls, GPR revealed a large rectangular building connected to a series of water pipes which lead to the aqueduct. Remarkably, these pipes can be traced across much of Falerii Novi, running beneath its insulae (city blocks), and not just along its streets, as might normally be expected. The team believes that this structure was an open-air natatio or pool, forming part of a substantial public bathing complex.Even more unexpectedly, near the city's north gate, the team identified a pair of large structures facing each other within a porticus duplex (a covered passageway with central row of columns). They know of no direct parallel but believe these were part of an impressive public monument, and contributed to an intriguing sacred landscape on the city's edge.Corresponding author, Professor Martin Millett from the University of Cambridge's Faculty of Classics, said:"The astonishing level of detail which we have achieved at Falerii Novi, and the surprising features that GPR has revealed, suggest that this type of survey could transform the way archaeologists investigate urban sites, as total entities."Millett and his colleagues have already used GPR to survey Interamna Lirenas in Italy, and on a lesser scale, Alborough in North Yorkshire, but they now hope to see it deployed on far bigger sites."It is exciting and now realistic to imagine GPR being used to survey a major city such as Miletus in Turkey, Nicopolis in Greece or Cyrene in Libya," Millett said. "We still have so much to learn about Roman urban life and this technology should open up unprecedented opportunities for decades to come."The sheer wealth of data produced by such high-resolution mapping does, however, pose significant challenges. Traditional methods of manual data analysis are too time consuming, requiring around 20 hours to fully document a single hectare. It will be some time before the researchers finish examining Falerii Novi but to speed the process up they are developing new automated techniques.Falerii Novi is well documented in the historical record, is not covered by modern buildings and has been the subject of decades of analysis using other non-invasive techniques, such as magnetometry, but GPR has now revealed a far more complete picture.*GPR is so effective because it relies on the reflection of radio waves off items in the ground. Different materials reflect waves differently, which can be used to create maps of underground features. Although this principle has been employed since the 1910s, over the past few years technological advances have made the equipment faster and higher resolution.The project was funded by the AHRC. Lieven Verdonck, from Ghent University, was employed on a post-doctoral fellowship from the Fund for Scientific Research -- Flanders (FWO). The team is grateful for support from Soprintendenza Archeologia, Belle Arti e Paesaggio per l'Area Metropolitana di Roma, la Provincia di Viterbo e l'Etruria Meridionale.
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Geography
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June 8, 2020
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https://www.sciencedaily.com/releases/2020/06/200608114710.htm
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Countries must work together on CO2 removal to avoid dangerous climate change
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The Paris Agreement lays out national quotas on CO
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The Paris Agreement aims to keep global temperature rise this century well below 2°C above pre-industrial levels and to pursue efforts to limit it to 1.5°C. Reaching these targets will require mitigation -- lowering the carbon dioxide (COHowever, while countries signed up to the Paris Agreement have individual quotas they need to meet in terms of mitigation and have individual plans for doing so, there are no agreed national quotas for CONow, in a paper published today in The team, from Imperial College London, the University of Girona, ETH Zürich and the University of Cambridge, say countries need to start working together now to make sure enough COCo-author Dr Niall Mac Dowell, from the Centre for Environmental Policy and the Centre for Process Systems Engineering at Imperial, said: "Carbon dioxide removal is necessary to meet climate targets, since we have so far not done enough to mitigate our emissions. Both will be necessary going forward, but the longer we wait to start removing CO"It is imperative that nations have these conversations now, to determine how quotas could be allocated fairly and how countries could meet those quotas via cross-border cooperation. It will work best if we all work together."Co-author Dr David Reiner, from Judge Business School at the University of Cambridge, added: "Countries such as the UK and France have begun to adopt binding 'net-zero targets' and whereas there has been extensive focus on greenhouse gas emissions and emissions reductions, meeting these targets will require greater attention to the negative emissions or carbon dioxide removal side of the equation."A critical element in any negotiations will be to determine the fairest way to allocate quotas to different nations. Different methods have been used for determining previous quotas, such as the ability of a country to pay and its historic culpability (how much COThe team modelled several of these different methods and applied them to countries across Europe. While the quotas varied significantly, they found that only a handful of countries could meet any of the quotas using only their own resources.Co-lead author Dr Ángel Galán-Martín, from ETH Zürich, said: "The exercise of allocating COCarbon dioxide removal can be achieved in several ways. Reforestation uses trees as natural absorbers of atmospheric COCCS is usually coupled with a fossil fuel power station to take the COHowever, different countries have varying abilities to deploy these COThe authors therefore suggest, after quotas have been determined, that a system of trading quotas could be established. For example, the UK has abundant space for CCS thanks to favourable geological formations in the North Sea, so could sell some of its capacity to other countries.This system would take a while to set up, so the authors urge nations to begin the process now. Co-lead author Dr Carlos Pozo from the University of Girona, said: "By 2050, the world needs to be carbon neutral -- taking out of the atmosphere as much CO"There are technological solutions ready to be deployed. Now it is time for international agreements to get the ball rolling so we can start making serious progress towards our climate goals."
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Geography
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June 7, 2020
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https://www.sciencedaily.com/releases/2020/06/200607195005.htm
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Climate change has degraded productivity of shelf sea food webs
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A shortage of summer nutrients as a result of our changing climate has contributed to a 50% decline in important North East Atlantic plankton over the past 60 years.
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New research, published in Changes from cloudier and wetter summers to longer periods of sunshine and drought have led to decreasing iron and nutrient supply to surface waters. This results in an increased period of suboptimal feeding conditions for zooplankton at a time of year when their metabolic demand is at its highest.In some areas, large phytoplankton are being almost completely replaced by picoplankton, especially the cyanobacterium Synechococcus, that flourishes when iron and nitrogen levels in surface waters are very low.However, its small size and lack of essential biomolecules mean it is unable to function in the same way as larger, more nutritious phytoplankton -- a vital primary producer of omega-3 -- and cannot sustain shelf sea food webs efficiently.With Synechococcus prominent from the tropics to the Arctic, and its abundance increasing worldwide, scientists suggest that competition for scarce summer nutrients will become a key force in structuring shelf sea food webs. Shelf seas provide around 80% of the world's wild-captured seafood, and changes in their productivity will have major effects on humans.The study was led by scientists at the University of Plymouth (funded through the Natural Environment Research Council's Shelf Sea Biogeochemistry Programme), working with colleagues from Plymouth Marine Laboratory, the Marine Biological Association, and the University of Southampton. It brought together experts from a range of fields including trace metal analysis, plankton taxonomy, and satellite data.Lead author Dr Katrin Schmidt, a plankton ecologist in the University of Plymouth's School of Geography, Earth and Environmental Sciences, said: "Zooplankton such as copepods are considered beacons of climate change, and the ~50% decline in their abundance over the last six decades is worrying. Our study is the first to provide a mechanism for such a wide-spread decline, and this understanding is essential to project future responses to climate change. We also need to explore the wider impacts and whether the changing nutrient supply could, for example, lead to reductions in omega-3 within the entire food chain."The study was based on an area measuring 2,000km by 1,500km in the North East Atlantic, and used a combination of data generated by satellites and the MBA's Continuous Plankton Recorder (CPR) survey. It allowed scientists to identify both longer and shorter-term trends, the spatial extent of any changes and the months that are most affected.It also used intensive field observations of the phytoplankton community and, by linking the two scales, provided a conceptual model of why the classical food web is increasingly under threat in temperate coastal and shelf areas.In combination, both satellite and CPR data show similar changes over the longer (1958-2017) and shorter (1997-2018) terms. Between May and August/September in those years, numbers of diatoms, dinoflagellates and total copepods have all declined, while the proportion of picophytoplankton has increased.Co-author Dr Luca Polimene, Senior Marine Ecosystem Modeller at Plymouth Marine Laboratory, said: "The increasing dominance of small phytoplankton species might have a broad impact on the marine ecosystem. Other than altering the food chain as suggested in this study, it could also change the biological carbon pump modifying the capacity of the ocean to store carbon. We need to make sure that the shift between large to small phytoplankton species is well captured by marine ecosystem models if we want to reliably simulate future oceans."David Johns, Head of the Continuous Plankton Recorder Survey, added: "While the CPR Survey samples the larger plankton community, declines in some key groups over past decades can be linked to changes in the smallest plankton that are driven by climate change. We have previously witnessed direct climate impacts on the plankton community, from seasonality (temporal) to large scale movements (spatial), via changes in temperature. This study demonstrates a knock-on effect through the food web, and it is only by continuing our monitoring that we will identify multiple stressors acting on our marine environment, and hopefully sustain and protect our productive oceans."
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Geography
| 2,020 |
June 5, 2020
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https://www.sciencedaily.com/releases/2020/06/200605132433.htm
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American lobster, sea scallop habitat could shift off the northeast
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Researchers have projected significant changes in the habitat of commercially important American lobster and sea scallops on the Northeast U.S. continental shelf. They used a suite of models to estimate how species will react as waters warm. The researchers suggest that American lobster will move further offshore and sea scallops will shift to the north in the coming decades.
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Findings from the study were published recently in "Changes in stock distribution affect where fish and shellfish can be caught and who has access to them over time," said Vincent Saba, a fishery biologist in the Ecosystems Dynamics and Assessment Branch at the Northeast Fisheries Science Center and a co-author of the study. "American lobster and sea scallop are two of the most economically valuable single-species fisheries in the entire United States. They are also important to the economic and cultural well-being of coastal communities in the Northeast. Any changes to their distribution and abundance will have major impacts," he said.Saba and study colleagues used a group of species distribution models and a high-resolution global climate model. They projected the possible impact of climate change on suitable habitat for the two species in the Northeast U.S. continental shelf large marine ecosystem. That ecosystem includes waters of the Gulf of Maine, Georges Bank, the Mid-Atlantic Bight, and Southern New England.The high-resolution global climate model is, known as NOAA's CM2.6. It generated projections of future ocean bottom temperatures and salinity conditions across the ecosystem, and identified where suitable habitat would occur for the two species. The CM2.6 model was developed by the NOAA Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey, where Saba is located.To reduce bias and uncertainty in the model projections, the team used nearshore and offshore fisheries independent trawl survey data to train the habitat models. Those data were collected on multiple surveys over a wide geographic area from 1984 to 2016. The model combined this information with historical temperature and salinity data. It also incorporated 80 years of projected bottom temperature and salinity changes in response to a high greenhouse gas emissions scenario. That scenario has an annual 1 percent increase in atmospheric carbon dioxide.American lobster are large, mobile animals that migrate to find optimal biological and physical conditions. Sea scallops are bivalve mollusks that are largely sedentary, especially during their adult phase. Both species are affected by changes in water temperature, salinity, ocean currents, and other oceanographic conditions.Projected warming over the next 80 years showed deep areas in the Gulf of Maine becoming increasingly suitable lobster habitat. During the spring, western Long Island Sound and the area south of Rhode Island in the Southern New England region showed habitat suitability. That suitability decreased in the fall. Warmer water in these southern areas has led to a significant decline in the lobster fishery in recent decades.Sea scallop distribution showed a clear northerly trend, with declining habitat suitability in the Mid-Atlantic Bight, Southern New England, and Georges Bank areas."This study suggests that ocean warming due to climate change will act as a likely stressor to the ecosystem's southern lobster and sea scallop fisheries and continues to drive further contraction of sea scallop and lobster habitats into the northern areas," Saba said. "Our study only looked at ocean temperature and salinity, but other factors such as ocean acidification and changes in predation can also impact these species.""Ensemble modelling approaches like the one developed in this study can contribute to lobster and scallop assessments by improving the effectiveness of survey efforts and the precision of stock assessment models," Saba added. "It also provides a critical step toward establishing long-term adaptive management plans for these two valuable species."
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Geography
| 2,020 |
June 5, 2020
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https://www.sciencedaily.com/releases/2020/06/200605121521.htm
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Measuring Atlantic bluefin tuna with a drone
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Researchers have used an unmanned aerial system (or drone) to gather data on schooling juvenile Atlantic bluefin tuna in the Gulf of Maine.
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This pilot study tested whether a drone could keep up with the tuna while also taking photographs that captured physical details of this fast-moving fish. The drone was equipped with a high-resolution digital still image camera. Results show that drones can capture images of both individual fish and schools. They may be a useful tool for remotely monitoring behavior and body conditions of the elusive fish.Individual fish lengths and widths, and the distance between fish near the sea surface, were measured to less than a centimeter of precision. We used an APH-22, a battery-powered, six-rotor drone. The pilot study was conducted in the Atlantic bluefin tuna's foraging grounds northeast of Cape Cod in the southern Gulf of Maine."Multi-rotor unmanned aerial systems won't replace shipboard surveys or the reliance on manned aircraft to cover a large area," said Mike Jech, an acoustics researcher at the Northeast Fisheries Science Center in Woods Hole, Massachusetts and lead author of the study. "They have a limited flight range due to battery power and can only collect data in bursts. Despite some limitations, they will be invaluable for collecting remote high-resolution images that can provide data at the accuracy and precision needed by managers for growth and ecosystem models of Atlantic bluefin tuna."Results from the APH-22 study were published in March 2020 in the Atlantic bluefin tuna is a commercially and ecologically important fish. The population size in the western Atlantic Ocean is unknown. Fishery managers need biological data about this population, but it is hard to get. Highly migratory species like Atlantic bluefin tuna often move faster than the vessels trying to sample them. The tuna are distributed across large areas, and can be found from the sea surface to hundreds of feet deep.Sampling with traditional gear -- nets and trawls -- is ineffective. Acoustical methods are useful but limited to sampling directly below a seagoing vessel with echosounders or within range of horizontal sonar.It is also difficult to estimate the number of tuna in a school from an airplane. Both fish availability and perception biases introduced by observers can affect results. Estimates of abundance and size of individuals within a school are hard to independently verify.Taking precision measurements of animals that are in constant motion near the surface proved easier with a drone that is lightweight, portable, and agile in flight. It can carry a high-quality digital still camera, and be deployed quickly from a small fishing boat.Short flight times limit a drone's ability to survey large areas. However, they can provide two-dimensional images of the shape of a fish school and data to count specific individuals just below the ocean surface.The APH-22 system has been tested and evaluated for measuring other marine animals. It's been used in a number of environments -- from Antarctica to the Pacific Ocean -- prior to its use in the northwest Atlantic Ocean. Previous studies estimated the abundance and size of penguins and leopard seals, and the size and identity of individual killer whales."The platform is ideal for accurately measuring fish length, width, and the distance between individuals in a school when you apply calibration settings and performance measures," Jech said. "We were able to locate the hexacopter in three-dimensional space and monitor its orientation to obtain images with a resolution that allowed us to make measurements of individual fish."As new unmanned aerial systems are developed, their use to remotely survey Atlantic bluefin tuna and other animals at the sea surface will evolve. It may minimize the reliance on manned aircraft or supplement shipboard surveys.The International Commission for the Conservation of Atlantic Tunas governs tuna fishing. It is entrusted to monitor and manage tuna and tuna-like species in the Atlantic Ocean and adjacent seas. NOAA Fisheries manages the Atlantic bluefin tuna fishery in the United States and sets regulations for the U.S. fishery based on conservation and management recommendations from the international commission.
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Geography
| 2,020 |
June 4, 2020
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https://www.sciencedaily.com/releases/2020/06/200604111619.htm
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New study reveals cracks beneath giant, methane gushing craters
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A paper published in Science in 2017 described hundreds of massive, kilometer -wide, craters on the ocean floor in the Barents Sea. Today more than 600 gas flares are identified in and around these craters, releasing the greenhouse gas steadily into the water column. Another study, published the same year in PNAS, mapped several methane mounds, some 500m wide, in the Barents Sea. The mounds were considered to be signs of soon-to-happen methane expulsions that have created the said craters.
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The most recent study in "It turns out that this area has a very old fault system -- essentially cracks in bedrock that likely formed 250 million years ago. Craters and mounds appear along different fault structures in this system. These structures control the size, placement, and shape of the craters. The methane that is leaking through the seafloor originates from these deep structures and is coming up through these cracks." according to Malin Waage, a postdoc at CAGE, Centre for Arctic Gas Hydrate, Environment and Climate, and the first author of the study.The deep origin of craters and mounds was discovered using cutting edge 3D seismic technology which can penetrate deep into the ocean floor, and help scientists visualize the structures in the hard bedrock underneath."Our previous studies in the area hypothesized that climate warming and the retreat of the ice sheet some 20,000 years ago, caused the gas hydrates beneath the ice to melt leading to abrupt methane release and creating craters."Gas hydrates are a solid form of methane, among others, that is stable in cold temperatures and under pressure, which an enormous ice sheet provides. As the ocean warmed up, and the pressure of the ice sheet lifted, the methane ice in the seafloor melted and thus the craters were formed."This study, however, ads several layers to that picture, as we now see that there has been a structural weakness beneath these giant craters, for much longer than the last 20,000 years. Deep below the seafloor, the expansion of gas and release of water build up a muddy slurry which eventually erupted through the fractures and caused seafloor collapses and craters in the hard bedrock. Think of it as a building: A roof of a building can cave in if the ground structure is weak. We believe that this is what happened in the crater area after the last glaciation." says Waage.The exploration of petroleum resources in the Barents Sea is a hot topic in Norway and beyond as the area is a part of a vulnerable Arctic ecosystem. But the area's geological system is poorly understood."Our 3D survey covered approximately 20 percent of the entire crater area. We believe that it is important to understand if similar fault systems exist in the larger context of the Barents Sea because they potentially could pose a threat to marine operations."Some of the questions that scientists, society and the industry does not know the answer to are: Will these weak structures lead to unpredictable and explosive methane release? Can such release and related geohazards be triggered by drilling? And can the gas reach the atmosphere in case of abrupt blow-outs, adding to the greenhouse gas budget?"There is still very much that we don't know about this system. But we are currently collecting and analyzing new data in the Barents Sea, dominated by similar crater structures. This can help us map in bigger detail the fault systems and associated weakness. " says Waage.
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Geography
| 2,020 |
June 3, 2020
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https://www.sciencedaily.com/releases/2020/06/200603194431.htm
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Human activity threatens vertebrate evolutionary history
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A new study maps for the first time the evolutionary history of the world's terrestrial vertebrates: amphibians, birds, mammals and reptiles. It explores how areas with large concentrations of evolutionarily distinct species are being impacted by our ever-increasing "human footprint."
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Research for the study was led by Dr. Rikki Gumbs of the EDGE of Existence Programme at the Zoological Society of London and Imperial College London and Dr. James Rosindell of Imperial College London in collaboration with Prof. Shai Meiri of the School of Zoology at Tel Aviv University's George S. Wise Faculty of Life Sciences and Steinhardt Museum of Natural History and other colleagues. The study was published in "Being 'evolutionarily distinct' means that you have no close living relatives," explains Prof. Meiri, who generated and interpreted the reptile-related data for the study. "In other words, you are alone on your branch of the evolutionary tree of life. Aardvarks, crocodiles, and kiwis were all separated from their closest evolutionary relatives tens of millions of years ago and bear a unique evolutionary history."The new research will provide a clear understanding of how best to protect nature given the current threats to specific locations and endangered species."The researchers developed two new metrics that combine phylogenetic diversity and the extent of human pressure across the spatial distribution of species -- one metric valuing regions and another prioritizing species. They evaluated these metrics for reptiles, which have been largely neglected in previous studies, and contrasted these results with equivalent calculations for all terrestrial vertebrate groups. The researchers found that regions under high human pressure coincided with those containing irreplaceable reptilian diversity."Our analyses reveal the incomprehensible scale of the losses we face if we don't work harder to save global biodiversity," says Dr. Gumbs, the lead author on the paper. "To put some of the numbers into perspective, reptiles alone stand to lose at least 13 billion years of unique evolutionary history, roughly the same number of years as have passed since the beginning of the entire universe."Using extinction-risk data for around 25,000 species, the researchers found at least 50 billion years of evolutionary heritage to be under threat, as well as a large number of potentially threatened species for which we lack adequate extinction risk data. This suggests that the calculation underestimates the number of species that may be affected.According to the study's calculations, the Caribbean, the Western Ghats of India, and large parts of Southeast Asia -- regions that are home to the most unique evolutionary history -- are facing unprecedented levels of human-related devastation."This new study highlights which species should be prioritized for conservation, based on their evolutionary uniqueness and the intense human impact on environments where they are thought to dwell," Prof. Meiri says.According to the research, the greatest losses of evolutionary history will be driven by the extinction of entire groups of closely-related species, such as pangolins and tapirs, and by the loss of highly evolutionarily distinct species, such as the ancient Chinese crocodile lizard (The study highlights several unusual species as urgent conservation priorities, including the punk-haired Mary River turtle ("These are some of the most incredible and overlooked animals on Planet Earth," says Dr. Gumbs. "From legless lizards and tiny blind snakes to pink worm-like amphibians called caecilians, we know precious little about these fascinating creatures, many of which may be sliding silently toward extinction."The study also identifies regions where concentrations of irreplaceable diversity are currently under little to no human pressure, particularly across the Amazon rainforest, the highlands of Borneo, and parts of southern Africa.Co-author Dr. Rosindell concludes, "Our findings highlight the importance of acting urgently to conserve these extraordinary species and the remaining habitat that they occupy -- in the face of intense human pressures."
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Geography
| 2,020 |
June 3, 2020
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https://www.sciencedaily.com/releases/2020/06/200603132341.htm
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New laser system provides 3D reconstructions of living deep-sea animals and mucus filters
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Living in an essentially zero-gravity environment, many deep-sea animals have evolved soft, gelatinous bodies and collect food using elaborate mucus filters. Until now, studying these delicate structures has been virtually impossible. A new study published in the journal
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According to Kakani Katija, MBARI Principal Engineer and the lead author on the new paper, "Mucus is ubiquitous in the ocean, and complex mucus structures are made by animals for feeding, health, and protection. Now that we have a way to visualize these structures deep below the surface we can finally understand how they function and what roles they play in the ocean."For this study, the researchers focused on one of the most prolific mucus architects, deep-sea animals called larvaceans. Larvaceans are abundant throughout the world's ocean basins and range from less than one centimeter to about 10 centimeters in length. So-called "giant" larvaceans create balloon-like mucus webs that can be up to a meter across. Inside these outer filters are smaller, fist-sized inner filters that the animals use to feed on tiny particles and organisms, ranging from less than a micron to a few millimeters in size.Despite their insubstantial bodies, larvaceans remove vast amounts of carbon-rich food out of the surrounding water. When their mucus filters become clogged the animals release the mucus, which sinks rapidly to the seafloor. This helps the ocean remove carbon dioxide from the atmosphere and carries microplastics from the water column down to the seafloor.Researchers, like MBARI Senior Scientist and co-author Bruce Robison, have long been interested in how larvaceans can filter a wide variety of particles while processing very large volumes of water (up to 80 liters an hour). Previous studies have looked at smaller larvacean filters in the laboratory, but this is the first study to provide quantitative data about these mucus structures in the open ocean.To gather these data, Katija, who heads MBARI's Bioinspiration Lab, worked with a team of engineers, scientists, and submersible pilots to develop an instrument called DeepPIV (PIV stands for particle imaging velocimetry). Mounted on a remotely operated vehicle (ROV), the DeepPIV instrument projects a sheet of laser light that illuminates particles in the water, like dust motes in a sunbeam. By recording the movement of these particles in video, researchers can quantify tiny currents around marine animals as well as water flowing through their filters and their transparent bodies.During field deployments of the DeepPIV system, Katija and her colleagues discovered that, as the ROV moved back and forth, the sheet of laser light revealed a series of cross sections through the transparent, gelatinous bodies and the mucus filters of giant larvaceans. By assembling a series of these cross-sectional images, the team was able to create three-dimensional reconstructions of individual larvaceans and their filters, much as radiologists do following a CAT scan of a human body.Collecting high-fidelity video imagery required skilled piloting of MBARI's ROVs. "Using DeepPIV to collect these 3D cross sections is probably the hardest thing I've ever done with an ROV," said Knute Brekke, chief pilot for ROV Doc Ricketts. "We were using a 12,000 pound robot to move a millimeter-thick laser sheet back and forth through a larvacean and its fist-sized mucus filter that was drifting hundreds of meters below the ocean surface."Combining three-dimensional models of larvacean filters with observations of flow patterns through the filters, Katija and her collaborators were able, for the first time, to identify the shape and function of different parts of the larvacean's inner filter. Using 3D rendering software, they were able to virtually "fly through" the inner filter and study the flow of fluid and particles through different parts of the filter."Now we have a technique for understanding the form of these complex structures, and how they function," Katija explained. "No one has done in situ 3D reconstructions of mucus forms like this before.""Among other things, we're hoping to understand how larvaceans build and inflate these structures," she continued. "This could help us design better 3D printers or build complex inflatable structures that could be used in a number of environments," including underwater and in outer space.Expanding on this work, members of the Bioinspiration Lab are experimenting with new 3D plenoptic imaging systems that can capture highly-precise information about the intensity, color, and direction of light in a scene. They are also collaborating on the development of new underwater robots that will be able to follow gelatinous animals through the water for hours or days at a time."In this paper, we have demonstrated a new system that operates well with a variety of underwater vehicles and midwater organisms," said Katija. "Now that we have a tool to study the mucus filtering systems found throughout the ocean, we can finally bring to light some of nature's most complex structures.""DeepPIV has revealed a marvel of natural engineering in the structure of these complex and intricate filtering webs," said Robison. "And in DeepPIV, human engineering has produced a powerful new tool for investigating these and other mysteries of the deep ocean."
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Geography
| 2,020 |
June 3, 2020
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https://www.sciencedaily.com/releases/2020/06/200603130016.htm
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Ocean uptake of carbon dioxide could drop as carbon emissions are cut
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Volcanic eruptions and human-caused changes to the atmosphere strongly influence the rate at which the ocean absorbs carbon dioxide, says a new study. The ocean is so sensitive to changes such as declining greenhouse gas emissions that it immediately responds by taking up less carbon dioxide.
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The authors say we may soon see this play out due to the COVID-19 pandemic lessening global fuel consumption; they predict the ocean will not continue its recent historic pattern of absorbing more carbon dioxide each year than the year before, and could even take up less in 2020 than in 2019."We didn't realize until we did this work that these external forcings, like changes in the growth of atmospheric carbon dioxide, dominate the variability in the global ocean on year-to-year timescales. That's a real surprise," said lead author Galen McKinley, a carbon cycle scientist at Columbia University's Lamont-Doherty Earth Observatory. "As we reduce our emissions and the growth rate of atmospheric carbon dioxide slows down, it's important to realize that the ocean carbon sink will respond by slowing down."The paper, published today in the journal A carbon sink is a natural system that absorbs excess carbon dioxide from the atmosphere and stores it away. Earth's largest carbon sink is the ocean. As a result, it plays a fundamental role in curbing the effects of human-caused climate change. Nearly 40 percent of the carbon dioxide added to the atmosphere by fossil fuel burning since the dawn of the industrial era has been taken up by the ocean.There's variability in the rate at which the ocean takes up carbon dioxide, which isn't fully understood. In particular, the scientific community has puzzled over why the ocean briefly absorbed more carbon dioxide in the early 1990s and then slowly took up less until 2001, a phenomenon verified by numerous ocean observations and models.McKinley and her coauthors addressed this question by using a diagnostic model to visualize and analyze different scenarios that could have driven greater and lesser ocean carbon uptake between 1980 and 2017. They found the reduced ocean carbon sink of the 1990s can be explained by the slowed growth rate of atmospheric carbon dioxide early in the decade. Efficiency improvements and the economic collapse of the Soviet Union and Eastern European countries are thought to be among the causes of this slowdown.But another event also affected the carbon sink: The massive eruption of Mount Pinatubo in the Philippines in 1991 caused the sink to temporarily become much larger coincident with the eruption."One of the key findings of this work is that the climate effects of volcanic eruptions such as those of Mount Pinatubo can play important roles in driving the variability of the ocean carbon sink," said coauthor Yassir Eddebbar, a postdoctoral scholar at Scripps Institution of Oceanography.Pinatubo was the second-largest volcanic eruption of the 20th century. The estimated 20 million tons of ash and gases it spewed high into the atmosphere had a significant impact on climate and the ocean carbon sink. The researchers found that Pinatubo's emissions caused the ocean to take up more carbon in 1992 and 1993. The carbon sink slowly declined until 2001, when human activity began pumping more carbon dioxide into the atmosphere. The ocean responded by absorbing these excess emissions."This study is important for a number of reasons, but I'm most interested in what it means for our ability to predict the near-term, one to ten years out, future for the ocean carbon sink," said coauthor said Nicole Lovenduski, an oceanographer at the University of Colorado Boulder. "The future external forcing is unknown. We don't know when the next big volcanic eruption will occur, for example. And the COVID-19-driven carbon dioxide emissions reduction was certainly not anticipated very far in advance."Investigating how the Pinatubo eruption impacted global climate, and thus the ocean carbon sink, and whether the drop in emissions due to COVID-19 is reflected in the ocean are among the research team's next plans.By understanding variability in the ocean carbon sink, the scientists can continue to refine projections of how the ocean system will slow down.McKinley cautions that as global emissions are cut, there will be an interim phase where the ocean carbon sink will slow down and not offset climate change as much as in the past. That extra carbon dioxide will remain in the atmosphere and contribute to additional warming, which may surprise some people, she said."We need to discuss this coming feedback. We want people to understand that there will be a time when the ocean will limit the effectiveness of mitigation actions, and this should also be accounted for in policymaking," she said.The study was coauthored by Amanda Fay and Lucas Gloege of Columbia University's Lamont-Doherty Earth Observatory.
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Geography
| 2,020 |
June 3, 2020
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https://www.sciencedaily.com/releases/2020/06/200603100519.htm
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'Major gaps' in understanding how land-use changes affect spread of diseases
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The quest to discover how new diseases -- such as Covid-19 -- emerge and spread in response to global land-use change driven by human population expansion still contains "major gaps," researchers have claimed.
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A team of experts from the University of Exeter has conducted a major study of how land-use changes, such as deforestation and urbanisation, influence the spread of diseases from mammals to humans.Most new viruses and other pathogens that arise in humans are transmitted from other animals, as in the case of the virus that has caused Covid-19.In the new review study, the researchers pinpointed one of the key factors that affect this transmission -- the changes in land-use such as deforestation, urbanisation, and conversion to agriculture.The effect of these land-use changes on the behaviour of animals, including rodents, livestock and other mammals, and risk of disease spread to humans has been mainly studied within the context of urbanisation.The review, published in the journal Orly Razgour, co-author and from the University of Exeter, said: "In this review, we highlight major gaps in our understanding of how land-use change affects the spread of diseases from mammals to humans, in terms of how key hosts, like bats, are affected, and how important land-use changes, such as agriculture, impact wild mammals and their interaction with livestock. There is an urgent need for more studies that link animal ecology and responses to land-use change with pathogen ecology and disease spread."Around 75 per cent of emerging human pathogens, such as viruses, are transmitted from animals to humans. These include emerging infectious diseases (EIDs) -- newly recognised or reappearing diseases detected in a population for the first time and which spread rapidly, such as covid-19.While it is important to identify the source of the outbreak and the factors that allow these EID's to spread, the researchers claim that many methods for collecting such data are still under development.Crucially, while areas such as South America and Asia have been studied more extensively, along with the effects of urbanisation, large swathes of the world including Africa are less well studied.The researchers have called for more extensive studies to be conducted worldwide, to not only improve our understanding of how these diseases spread, but also to help policymakers identify the factors that alter the risk of emergence.Rebekah White, co-author and also from the University of Exeter, added: "We need reliable surveillance and an understanding of how zoonotic diseases are able to spread to humans, but our results show that this information is not yet available for all hosts and pathogens. In fact, the epidemiology of many zoonotic pathogens is yet to be considered in relation to land use change at all, despite evidence suggesting that these changes can increase the risk of a disease emerging."
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Geography
| 2,020 |
June 2, 2020
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https://www.sciencedaily.com/releases/2020/06/200602110138.htm
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Global warming will boost agriculture weed threat
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Working with computer models to predict the likely impact of climate change on invasive weed propagation, Dr Farzin Shabani from Flinders University's Global Ecology Lab found a likely increase in areas of habitat suitability for the majority of invasive weed species in European countries, parts of the US and Australia, posing a great potential danger to global biodiversity.
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In predicting the impact of climate change on current and future global distributions of invasive weed species, Dr Shabani also found that existing attempts to eradicate invasive populations are inadequate.Dr Shabani and an international team of researchers investigated 32 globally important Invasive Weed Species to assess whether climate alteration may lead to spatial changes in the overlapping of specific IWS globally."We aimed to evaluate the potential alterations -- whether that be a gain, loss or static -- in the number of potential ecoregion invasions by IWS, under climate change scenarios," says Dr Shabani. "We utilised all possible greenhouse gas concentration to examine a range of possible outcomes."The paper -- Invasive weed species' threats to global biodiversity: Future scenarios of changes in the number of invasive species in a changing climate, by Farzin Shabani, Mohsen Ahmadi, Lalit Kumar, Samaneh Solhjouy-fard, Mahyat Shafapour Tehrany, Fariborz Shabani, Bahareh Kalantar and Atefeh Esmaeili -- has been published in the journal Initially, the researchers modelled the current climatic suitability of habitat for each of the weeds, identifying those with a common spatial range of suitability. They then modelled the suitability of all 32 species under the projected climate for 2050, incorporating different scenarios.The final methodological step compared the extent of overlaps and alterations of weed habitats under the current and future projected climates."Under future climatic conditions, our results mainly predicted decrease on a global scale, with reduced areas of habitat suitable for most Invasive Weed Species -- but significantly this excluded European countries, northern Brazil, eastern US, and south-eastern Australia, which are all highly productive agricultural regions," says Dr Shabani.The study also revealed that Invasive Weed Species would most likely develop alterations in their habitat suitability in most parts of the world in the future."Even though our future projections indicate a decreasing rate in threats from invasive weeds in extensive areas across the world, the current distributions of many species still have a potential for expansion," says Dr Shabani."Many of these invasive weeds pose a threat in suitable habitats under both current and future climate conditions."Dr Shabani is concerned that Invasive Weed Species are rarely mentioned in biodiversity policy documents, except to focus on a few high-profile species. "There are no comprehensive national invasive species statutory controls, which is our concern," he says. "We believe that a national framework is needed for prevention and early detection, along with a coherent policy framework, a robust monitoring framework, a fund for strategic research, and a national training and action program."
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Geography
| 2,020 |
June 2, 2020
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https://www.sciencedaily.com/releases/2020/06/200602110111.htm
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Good night? Satellite data uncovers dolphins on the move at nighttime
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More than 1,000 bottlenose dolphins live in the Indian River Lagoon year-round. This estuarine system along the southeast coast of Florida is a narrow and convoluted ecosystem with interconnected bodies of water, a handful of ocean inlets, and numerous small rivers, creeks and canals that release freshwater into the lagoon. While this population of dolphins in the lagoon has been studied extensively, what they do at nighttime is still a mystery.
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Researchers from Florida Atlantic University's Harbor Branch Oceanographic Institute in collaboration with Seven Degrees of Mapping LLC, and Hubbs-SeaWorld Research Institute, are the first to use satellite telemetry on this dolphin population, providing unique insights into their behavioral ecology during the overnight hours. Detailed information about their nocturnal movements and habitat use will give scientists a more complete ecological understanding of this population. These dolphins face many direct and indirect threats including boat strikes, entanglements, and environmental contamination.Results of the study, published in the journal The study also highlights how much variation occurs within a population -- researchers found individual differences with almost every aspect studied in these dolphins. Individual spatial use varied by dolphin, with home ranges and core areas of different sizes spaced throughout the southern region of the lagoon. Researchers also discovered extensive individual variation in niche preferences."There are many possible reasons for the difference in space use and movement patterns, including prey preference and distribution such as traveling between nearby hotspots versus long distances between food sources or the size or age of the dolphins," said Greg O'Corry-Crowe, Ph.D., project lead and a research professor at FAU's Harbor Branch. "For example, two of the dolphins in our study were smaller and younger, while the other two were larger and older. The differences we observed could also be linked to more complex aspects that are influenced by social factors, differences in predator avoidance strategies, and individual response to human disturbance."One of the areas showing less variation was inlet use. Three out of four dolphins exhibited a strong nocturnal preference for habitats close to inlets, with one individual regularly using multiple inlets. Inlets may be important nocturnal foraging habitats as well as corridors for movement between ecosystems.Satellite telemetry is a powerful research tool that tracks the movement of an animal using orbiting satellites that detect signals emitted from a transmitter attached to the animal. For the study, the researchers attached satellite tags (SPOT 100 tags, Wildlife Computers) on the lower third of the trailing edge of the dorsal fin of four male dolphins, aged 6 to 21 years. The satellite tags recorded location data via the Argos satellite system. The tags were set to transmit constantly until 250 transmissions were reached in each 24-hour cycle. Satellite tags remained active between 129 and 140 days.O'Corry-Crowe, Elizabeth F. Hartel, M.S., lead author, Seven Degrees of Mapping LLC, and co-author Wendy Noke Durden, M.S., Hubbs-SeaWorld Research Institute, suggest that incorporating satellite telemetry into long-term studies of bottlenose dolphins in other regions may provide essential information about their movements and habitat use that is not otherwise readily available."Collectively, findings from our study highlight the need for greater consideration of the nocturnal habits of cetacean species when conducting risk assessments, developing conservation action, and planning new research," said O'Corry-Crowe.
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Geography
| 2,020 |
June 4, 2020
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https://www.sciencedaily.com/releases/2020/06/200604095644.htm
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Climate change an imminent threat to glass sponge reefs
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Warming ocean temperatures and acidification drastically reduce the skeletal strength and filter-feeding capacity of glass sponges, according to new UBC research.
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The findings, published in Ranging from the Alaska-Canada border and down through the Strait of Georgia, the reefs play an essential role in water quality by filtering microbes and cycling nutrients through food chains. They also provide critical habitat for many fish and invertebrates, including rockfish, spot prawns, herring, halibut and sharks."Glass sponge reefs are 'living dinosaurs' thought to have been extinct for 40 million years before they were re-discovered in B.C. in 1986," said Angela Stevenson, who led the study as a postdoctoral fellow at UBC Zoology. "Their sheer size and tremendous filtration capacity put them at the heart of a lush and productive underwater system, so we wanted to examine how climate change might impact their survival."Although the reefs are subject to strong, ongoing conservation efforts focused on limiting damage to their delicate glass structures, scientists know little about how these sponges respond to environmental changes.For the study, Stevenson harvested Aphrocallistes vastus, one of three types of reef-building glass sponges, from Howe Sound and brought them to UBC where she ran the first successful long-term lab experiment involving live sponges by simulating their natural environment as closely as possible.She then tested their resilience by placing them in warmer and more acidic waters that mimicked future projected ocean conditions.Over a period of four months, Stevenson measured changes to their pumping capacity, body condition and skeletal strength, which are critical indicators of their ability to feed and build reefs.Within one month, ocean acidification and warming, alone and in combination, reduced the sponges' pumping capacity by more than 50 per cent and caused tissue losses of 10 to 25 per cent, which could starve the sponges."Most worryingly, pumping began to slow within two weeks of exposure to elevated temperatures," said Stevenson.The combination of acidification and warming also made their bodies weaker and more elastic by half. That could curtail reef formation and cause brittle reefs to collapse under the weight of growing sponges or animals walking and swimming among them.Year-long temperature data collected from Howe Sound reefs in 2016 suggest it's only a matter of time before sponges are exposed to conditions which exceed these thresholds."In Howe Sound, we want to figure out a way to track changes in sponge growth, size and area and area in the field so we can better understand potential climate implications at a larger scale," said co-author Jeff Marliave, senior research scientist at the Ocean Wise Research Institute. "We also want to understand the microbial food webs that support sponges and how they might be influenced by climate cycles."Stevenson credits bottom-up community-led efforts and strong collaborations with government for the healthy, viable state of the B.C. reefs today. Added support for such community efforts and educational programs will be key to relieving future pressures."When most people think about reefs, they think of tropical shallow-water reefs like the beautiful Great Barrier Reef in Australia," added Stevenson. "But we have these incredible deep-water reefs in our own backyard in Canada. If we don't do our best to stand up for them, it will be like discovering a herd of dinosaurs and then immediately dropping dynamite on them."The colossal reefs can grow to 19 metres in height and are built by larval sponges settling atop the fused dead skeletons of previous generations. In northern B.C. the reefs are found at depths of 90 to 300 metres, while in southern B.C., they can be found as shallow as 22 metres.The sponges feed by pumping sea water through their delicate bodies, filtering almost 80 per cent of microbes and particles and expelling clean water.It's estimated that the 19 known reefs in the Salish Sea can filter 100 billion litres of water every day, equivalent to one per cent of the total water volume in the Strait of Georgia and Howe Sound combined.
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Geography
| 2,020 |
June 2, 2020
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https://www.sciencedaily.com/releases/2020/06/200602110126.htm
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Big vegetarians of the reef drive fish evolution
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A new study reveals the diets of reef fish dictate how fast different species evolve. The breakthrough adds another piece to the fascinating evolutionary puzzle of coral reefs and the fishes that live on them.
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"Up until now we knew that many factors could have influenced the pace of reef fish evolution, but these factors were never examined altogether," said Alexandre Siqueira, the study's lead author from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU)."By building an evolutionary 'tree of life' for nearly all fishes associated with reefs, we were able to examine the variation in rates of species formation and ask what drives it," said co-author Dr Peter Cowman, also from Coral CoE at JCU.The 'tree of life' contains more than 6,000 fish species that live on coral reefs across the globe. Ecological and geographical data -- such as diet and geographical range -- were also gathered for the majority of these species.The authors were surprised to find that what really matters in reef fish evolution isn't geography, but what fish eat and how big they get."We found that the fastest way to have more species, or biodiversity, on a reef is to be big and vegetarian," said co-author Professor David Bellwood, also from Coral CoE at JCU."Herbivores, such as surgeonfishes and parrotfishes, are key to the ecological diversity of coral reefs today."The study suggests these fishes also made way for today's coral reefs to evolve and flourish."By feeding on the algae that compete with corals, herbivorous fishes may have also helped corals to expand through time," Mr Siqueira said."In turn, this expansion in the corals allowed the diversification of other reef fish groups that depend on them."And these herbivorous fishes -- big and small -- still maintain coral reefs to this day.The study offers a new way of looking at reefs with a functional, rather than taxonomic, approach. Very little is known about the functional evolution of reefs: what they do and how they work. Scientists previously only looked at how many reefs there were and what species were present."In this study it was important to understand the origins of the functional role a fish species plays on a reef -- not just the species itself," Dr Cowman said.Today's coral reefs differ from their early counterparts. It was only during the Miocene, less than 23 million years ago, that herbivorous fish species developed features that allowed them to explore different areas of the reef."Because of this, today's reefs are highly dynamic and have a fast turnover. These herbivores are the key element that established modern coral reefs," Prof Bellwood said."Understanding how reefs are constructed throughout their evolution means we can reach a better understanding of the fundamental processes that maintain them in a healthy state today," Mr Siqueira said.
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Geography
| 2,020 |
June 2, 2020
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https://www.sciencedaily.com/releases/2020/06/200602110121.htm
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Latest climate models show more intense droughts to come
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An analysis of new climate model projections by Australian researchers from the ARC Centre of Excellence for Climate Extremes shows southwestern Australia and parts of southern Australia will see longer and more intense droughts due to a lack of rainfall caused by climate change.
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But Australia is not alone. Across the globe, several important agricultural and forested regions in the Amazon, Mediterranean and southern Africa can expect more frequent and intense rainfall droughts. While some regions like central Europe and the boreal forest zone are projected to get wetter and suffer fewer droughts, those droughts they do get are projected to be more intense when they occur.The research published in "We found the new models produced the most robust results for future droughts to date and that the degree of the increase in drought duration and intensity was directly linked to the amount of greenhouse gases emitted into the atmosphere," said lead author Dr Anna Ukkola."There were only slight changes to the areas of drought under a mid-range emissions scenario versus a high-emissions pathway. However, the change in the magnitude of drought with a higher emissions scenario was more marked, telling us that early mitigation of greenhouse gases matters."Much of the earlier research into future droughts only considered changes to average rainfall as the metric to determine how droughts would alter with global warming. This often produced a highly uncertain picture.But we also know that with climate change, rainfall is likely to become increasingly variable. Combining metrics on variability and mean rainfall, the study increased clarity around how droughts would change for some regions.The researchers found the duration of droughts was very closely aligned to changes in the average rainfall, but the intensity of droughts was much more closely connected to the combination of average rainfall and variability. Regions with declining average rainfall like the Mediterranean, Central America and the Amazon are projected to experience longer and more frequent droughts. Meanwhile, other regions, such as the boreal forests are expected to experience shorter droughts in line with increasing average rainfall.However, the situation is different for drought intensity alone with most regions projected to experience more intense rainfall droughts due to increasing rainfall variability. Importantly, the researchers were unable to locate any region that showed a reduction in future drought intensity. Even regions with long-term increases in rainfall, such as central Europe, can expect more intense droughts as rainfall becomes more variable."Predicting future changes in drought is one of the greatest challenges in climate science but with this latest generation of models and the opportunity to combine different drought metrics in a more meaningful way we can gain a clearer insight into the future impacts of climate change," said Dr Ukkola."However, while these insights grow clearer with each advance, the message they deliver remains the same -- the earlier we act on reducing our emissions, the less economic and social pain we will face in the future."
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Geography
| 2,020 |
June 1, 2020
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https://www.sciencedaily.com/releases/2020/06/200601134550.htm
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Measuring ocean acidification along US coasts
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One of the earth's biggest allies in the fight against global warming is the world's oceans. Since the industrial revolution, the burning of fossil fuels has caused carbon dioxide, the dominant greenhouse gas, to be released into the atmosphere. Approximately 25% of that carbon dioxide is taken each year from the atmosphere by the world's oceans -- without which, the earth's atmosphere would have a higher greenhouse gas concentration and temperature.
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While pulling the anthropogenic, or human-made, carbon dioxide from the atmosphere is good for the earth's system, it leads to problems for the world's oceans as dissolved carbon dioxide becomes carbonic acid and leads to ocean acidification, changing the chemistry of the world's oceans and impacting some of the life forms within it. In particular, the organisms that use calcium to build their carbonate skeletons -- such as corals or mollusks -- will have a harder time under acidified conditions.To help determine the causes of ocean acidification on both coasts of North America, University of Delaware professor Wei-Jun Cai teamed with the National Oceanic and Atmospheric Administration (NOAA) scientists, as well as professors and professionals from numerous research institutes, to conduct an in-depth study that looks at carbon dioxide uptake and ocean acidification in the coastal oceans of North America.While ocean acidification in North America has been studied in smaller, specific areas before, this is the first time that researchers have compared data from the east coast, west coast and Gulf of Mexico locations.Through this work, researchers were able to identify the similarities and differences of ocean acidification on both coasts, as well as point out hot spots that will be particularly vulnerable to ocean acidification in the future. The results of that research were recently published in Cai said that in order to adequately research ocean acidification, the work cannot be done by just a few people from one region or even one country. This study involved researchers in the United States, Mexico and Canada."In North America, as well as globally, we're trying to get as many countries involved as possible," said Cai, the Mary A.S. Lighthipe Professor in the School of Marine Science and Policy in UD's College of Earth, Ocean and Environment.For this particular project, the goal was to synthesize their findings to show how ocean acidification works in general for coastal oceans in North America and how those interact with the more localized physical and biological processes."Ocean acidification is everywhere, but this paper basically shows that, depending on the location, it can manifest very differently," said Cai.Sampling the same latitudinal locations on the east and west coasts, as well as the Gulf of Mexico, over the course of several research cruises, allowed the researchers to see different patterns for the east coast and the west coast of North America.The near equilibrium of ocean waters with the atmospheric carbon dioxide controls the large pattern of ocean acidification on the east coast and Gulf of Mexico while on the west coast, the ocean acidification is enhanced by an additional process known as upwelling.In the ocean waters of the east coast, the northbound Gulf Stream Current system brings warm, high-salinity waters from the tropics while the southbound Labrador Current brings cold, low-salinity waters from the Arctic and subarctic regions.Northern waters on the east coast are particularly sensitive to atmospheric carbon dioxide uptake, as the colder ocean temperature allows the ocean to take more carbon dioxide from the atmosphere.Rising carbon dioxide levels upset the balance of carbonate ions in seawater, making it difficult for some organisms, which have shells composed of the mineral calcium carbonate, to form their shells. Many of the organisms that are affected are critical for ecosystem health."The northeast and western coastal communities are very aware of this potential harm that ocean acidification could bring to their region because the marine organisms become more vulnerable sooner in the northern waters," said Cai.In the east coast's warmer southern waters, the researchers observed lower levels of dissolved inorganic carbon and a higher mineral saturation state, meaning that acidity is lower here when compared to the northern waters.On the west coast, a section of the ocean is influenced by the California Current System (CCS), which extends from the United States and Canadian border to Baja California. The CCS is characterized by strong, cold currents, and wind-driven upwelling events.Upwelling brings colder, nutrient-rich subsurface waters to the ocean's surface to replace surface water that has been pushed away by winds. "The water from the subsurface has low pH and high carbon dioxide, which causes stress to the biological system," said co-author Richard Feely of NOAA's Pacific Marine Environmental Laboratory (PMEL). "So the combination of the uptake of anthropogenic carbon dioxide from the atmosphere and the upwelling of CO"We tried to give the community, particularly the shellfish community or the stakeholders that care about the large-scale ocean acidification, the sense that both the northern waters and at these upwelling centers are most vulnerable to atmospheric COAreas of concern include the CCS and northern-latitude coastal regions, such as the Gulf of Maine in the Atlantic and the Gulf of Alaska in the Pacific, as they are particularly sensitive and vulnerable to anthropogenic carbon dioxide forcing.The research cruises took place between 2007 and 2018 -- with future ones scheduled for summer of 2020, 2021 and 2022 -- and the researchers would be out on the water for 35 to 40 days at a time.Cai said that this data collection would not have been possible without the large numbers of international collaborators. He is hopeful that by putting all of this data together, it can be used for future ocean acidification research. Cai also would like to expand this analysis to global scale."The different regional collaboration and synthesis efforts to put data together is really important," said Cai. "We need more of this kind of synthesis work to teach us how these different processes create regions of high and low vulnerability of marine life to ocean acidification."
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Geography
| 2,020 |
May 29, 2020
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https://www.sciencedaily.com/releases/2020/05/200529150718.htm
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A rising tide of marine disease? How parasites respond to a warming world
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Warming events are increasing in magnitude and severity, threatening many ecosystems worldwide. As the global temperatures continue to climb, it also raises uncertainties as to the relationship, prevalence, and spread of parasites and disease.
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A recent study from the University of Washington explores the ways parasitism will respond to climate change, providing researchers new insights into disease transmission. The paper was published May 18 in The review builds upon previous research by adding nearly two decades of new evidence to build a framework showing the parasite-host relationship under climate oscillations. Traditionally, climate-related research is done over long timescales, however this unique approach examines how increasingly frequent "pulse warming" events alter parasite transmission."Much of what is known about how organisms and ecosystems can respond to climate change has focused on gradual warming," said lead author Danielle Claar, a postdoctoral researcher at the UW School of Aquatic and Fishery Sciences. "Climate change causes not only gradual warming over time, but also increases the frequency and magnitude of extreme events, like heat waves."Claar explained that both gradual warming and pulse warming can and have influenced ecosystems, but do so in different ways. Organisms may be able to adapt and keep pace with the gradual warming, but an acute pulse event can have sudden and profound impacts.The 2013-2015 "blob" is one such extreme heat pulse event which has been linked to a massive die-off of sea stars along the Pacific coast of the U.S. and Canada. Many species of sea stars, including the large sunflower sea star, were decimated by a sudden epidemic of wasting disease. Five years later, populations in the region are still struggling to recover. The abnormally warm waters associated with the blob are thought to have favored the spread of the sea star-associated densovirus, the suggested cause of the disease.The authors compare the prevalence of these marine diseases to a rising tide, an ebbing tide, or a tsunami. Disease transmission can rise or ebb in concert with gradual warming or a series of pulse warming events. However, a severe pulse warming event could result in a tsunami, "initiating either a deluge or drought of disease," as was observed with sea stars along the Pacific Northwest.However, not all pulse heat events will cause the same response. What may benefit a particular parasite or host in one system can be detrimental in another. Warming can alter a parasite's life cycle, limit the range of suitable host species, or even impair the host's immune response. Some flatworms which target wildlife and humans cannot survive as long in warmer waters, decreasing their window for infecting a host. Another recent UW study found that parasites commonly found in sushi are on the rise with their numbers increasing 283-fold in the past 40 years, though the relationship between heat pulse events and their abundance is not yet clear."The relationships between hosts, parasites, and their corresponding communities are complex and depend on many factors, making outcomes difficult to predict," said Claar, who recommends researchers make predictions on a case-by-case basis for their individual systems.The authors conclude that rather than a straightforward tidal prediction, they would expect pulse warming to cause "choppy seas with the occasional rogue wave.""It is important that we are able to understand and predict how parasitism and disease might respond to climate change, so we can prepare for, and mitigate, potential impacts to human and wildlife health," said Claar.
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Geography
| 2,020 |
May 28, 2020
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https://www.sciencedaily.com/releases/2020/05/200528161101.htm
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Wildfires can alter Arctic watersheds for 50 years
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Climate change has contributed to the increase in the number of wildfires across the globe especially in the Arctic where forest fires, along with increased permafrost thaw, can dramatically shift stream chemistry and potentially harm both ecosystems and humans. Researchers at the University of New Hampshire have found that some of the aftereffects of a burn, like decreased carbon and increased nitrogen, can last up to five decades and could have major implications on nearby vital waterways like the Yenisei River that drains into the Arctic Ocean, and other similar waterways around the world.
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"Forest fires in this region of the Arctic used to happen about every hundred years and now we're seeing them every summer," said Bianca Rodríguez-Cardona '20G, who just received a Ph.D. in UNH's natural resources and Earth system sciences program. "This increase in fires leads to more input of inorganic solutes into local streams which can alter the chemistry and trigger issues like increased algae blooms and bacteria that can be harmful to humans who depend on these waterways for drinking water, fishing and their livelihood."In the study, recently published in the journal Nature's Boreal forests, forests that grow in high latitudes at low temperatures, have been burning with greater frequency due to longer growing seasons, warmer temperatures and changing weather patterns adding additional uncertainty to how these ecosystems will be affected. While other studies have documented the effects of wildfires on stream chemistry, few have evaluated how these changes will impact the processing and export of nutrients from Arctic watersheds."Arctic rivers transfer large quantities of nutrients to the Arctic Ocean, and river water chemistry could be dramatically changed in the coming decades as permafrost thaws and wildfires become more frequent," said William McDowell, professor of environmental science and a co-author on the study. The researchers say even though responses of arctic watersheds can vary from region to region, this offers further understanding of what could happen in other areas of the Arctic, like Alaska, Canada, Norway or Sweden.
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Geography
| 2,020 |
May 28, 2020
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https://www.sciencedaily.com/releases/2020/05/200528160547.htm
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Antarctic ice sheets capable of retreating up to 50 meters per day
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The ice shelves surrounding the Antarctic coastline retreated at speeds of up to 50 metres per day at the end of the last Ice Age, far more rapid than the satellite-derived retreat rates observed today, new research has found.
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The study, led by the Scott Polar Research Institute at the University of Cambridge, used patterns of delicate wave-like ridges on the Antarctic seafloor to calculate how quickly the ice retreated roughly 12,000 years ago during regional deglaciation.The ridges were produced where the ice sheet began to float, and were caused by the ice squeezing the sediment on the seafloor as it moved up and down with the movement of the tides. The images of these landforms are at unprecedented sub-metre resolution and were acquired from an autonomous underwater vehicle (AUV) operating about 60 metres above the seabed. The results are reported in the journal While modern satellites are able to gather detailed information about the retreat and thinning rates of the ice around Antarctica, the data only goes back a few decades. Calculating the maximum speed at which an ice sheet can retreat, using sets of these seafloor ridges, reveals historic retreat rates that are almost ten times faster than the maximum observed rates of retreat today."By examining the past footprint of the ice sheet and looking at sets of ridges on the seafloor, we were able to obtain new evidence on maximum past ice retreat rates, which are very much faster than those observed in even the most sensitive parts of Antarctica today," said lead author Professor Julian Dowdeswell, Director of the Scott Polar Research Institute.The study was carried out as part of the Weddell Sea Expedition, which set out in early 2019 to undertake a science programme and to find Sir Ernest Shackleton's doomed ship Endurance. Although sea ice conditions at the time prevented the team from acquiring imagery of the legendary wreck, they were able to continue with their scientific work, including mapping of the seafloor close to the Larsen Ice Shelf, east of the Antarctic Peninsula.Using drones, satellites and AUVs, the researchers were able to study ice conditions in the Weddell Sea in unprecedented detail.Their goals were to investigate the present and past form and flow of the ice shelves, the massive floating sections of ice that skirt about 75% of the Antarctic coastline, where they act as a buttress against ice flow from inland.Like much of the rest of the ice in the polar regions, these buttresses are weakening in some parts of Antarctica, as witnessed most dramatically at the Larsen A and B ice shelves, which collapsed rapidly in 1998 and 2002, when roughly 1250 square miles of ice fragmented and collapsed in little over a month.The ice shelves are thinning because relatively warm water currents are eating away at them from below, but they're also melting from the top as summer air temperatures rise. Both these effects thin and weaken the ice shelves and, as they do, the glaciers they are holding back flow faster to the sea and their margins retreat.Using AUVs, the team were able to gather data on historic ice shelf fluctuations from the geological record on the Antarctic continental shelf."By examining landforms on the seafloor, we were able to make determinations about how the ice behaved in the past," said Dowdeswell, who was chief scientist on the Weddell Sea Expedition. "We knew these features were there, but we've never been able to examine them in such great detail before."The team identified a series of delicate wave-like ridges on the seafloor, each only about one metre high and spaced 20 to 25 metres apart, dating to the end of the last great deglaciation of the Antarctic continental shelf, roughly 12,000 years ago. The researchers have interpreted these ridges as formed at what was formerly the grounding line -- the zone where grounded ice sheet begins to float as an ice shelf.The researchers inferred that these small ridges were caused by the ice moving up and down with the tides, squeezing the sediment into well-preserved geological patterns, looking a little like the rungs of a ladder, as the ice retreated. Assuming a standard 12-hour cycle between high and low tide, and measuring the distance between the ridges, the researchers were then able to determine how fast the ice was retreating at the end of the last Ice Age.They calculated that the ice was retreating as much as 40 to 50 metres per day during this period, a rate that equates to more than 10 kilometres per year. In comparison, modern satellite images show that even the fastest-retreating grounding lines in Antarctica today, for example in Pine Island Bay, are much slower than these geological observations, at only about 1.6 kilometres per year."The deep marine environment is actually quite quiet offshore of Antarctica, allowing features such as these to be well-preserved through time on the seafloor," said Dowdeswell. "We now know that the ice is capable of retreating at speeds far higher than what we see today. Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise."The research was funded in part by the Flotilla Foundation and Marine Archaeology Consultants Switzerland.
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Geography
| 2,020 |
May 28, 2020
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https://www.sciencedaily.com/releases/2020/05/200528160536.htm
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Environmental groups moving beyond conservation
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Although non-governmental organizations (NGOs) have become powerful voices in world environmental politics, little is known of the global picture of this sector. A new study shows that environmental groups are increasingly focused on advocacy in climate change politics and environmental justice. How they do their work is largely determined by regional disparities in human and financial resources.
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To understand what these groups are doing and why, researchers from McGill University, the University of Georgia, and the Leibniz Centre of Tropical Marine Research analyzed data from 679 environmental NGOs worldwide in a study for These organizations are usually thought to focus on environmental protection and conservation. However, in examining the mission statements of these groups, the researchers found that the importance of climate politics (engagement on climate change) and environmental justice (respect for nature and human rights) had been grossly underestimated in previous research. They calculated a power index for the NGOs based on their human and financial resources and found that more than 40% of the most powerful organizations focus on these areas in their mission."There are more powerful organizations working on climate issues than on issues of biodiversity loss or land degradation," says co-author Klara Winkler, a postdoctoral researcher from McGill University. "It is important to be aware that some environmental issues garner more attention than others because it means that these other issues risk being neglected or even forgotten."The study also shows regional disparities in human resources and financial capacity. Environmental NGOs in Africa and Oceania have the lowest median number of employees and African NGOs have the lowest median annual budgets. While organizations in North America and Europe have the highest median financial capacity, Latin America and the Caribbean has the highest median number of employees.According to the researchers, these differences likely reflect both labor costs and financial flows, where environmental NGOs in the Global South employ more people with less money while groups in the Global North handle more money with fewer employees. This disparity is also indicative of a global division of labor where Northern environmental NGOs act as donors or coordinators for large projects, while Southern organizations are subcontracted for implementation."The findings give us an indication of how feasible it is for NGOs to advocate and implement their agendas in practice. Seeing where the disparities and limitations are in different regions can help us better understand observed differences in environmental policies and politics," says co-author Stefan Partelow from the Leibniz Centre for Tropical Marine Research in Germany.
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Geography
| 2,020 |
May 28, 2020
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https://www.sciencedaily.com/releases/2020/05/200528160505.htm
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New Zealand blue whale distribution patterns tied to ocean conditions, prey availability
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Oregon State University researchers who recently discovered a population of blue whales in New Zealand are learning more about the links between the whales, their prey and ocean conditions that are changing as the planet warms.
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Understanding how changes in climate affect the ability of blue whales to feed gives researchers more insight into the whales' overall health and provides critical information for conservation and management, said Leigh Torres, an assistant professor and director of the Geospatial Ecology of Marine Megafauna Laboratory at OSU's Marine Mammal Institute."These whales don't move around at random. We found that the same ocean patterns that determine where whales are also determine where their prey are, under both typical and warm ocean conditions," Torres said. "The more we learn about what drives these whales' movement, the more we can help protect them from whatever threats they face."The researchers' findings were published today in the journal Torres, Barlow and colleagues recently documented this new population of New Zealand blue whales, which is genetically distinct from other blue whale populations and spends much of its time in the South Taranaki Bight between New Zealand's North and South Islands."The goal of our study is to understand the habitat use patterns of this population of blue whales -- why they are where they are and how they respond to changing ocean conditions," Barlow said. "We know this area is important to this population of whales, and we want to understand what it is about this spot that is desirable to them."The region is often rich in prey -- blue whales feast on patches of krill -- but the prey is patchy and influenced by changing ocean conditions, including warmer temperatures and changes in ocean properties. The South Taranaki Bight also sees frequent shipping traffic and activity from oil and gas exploration and production, Torres said.Using data collected during typical summer conditions in 2014 and 2017 and warmer than average conditions in 2016, the researchers analyzed how changing ocean conditions affect the blue whales' distribution in the region's waters and the availability and location of their prey within the water column.They found that during a regional marine heat wave in 2016, there were fewer aggregations of krill for the whales to dine on. With fewer options, the whales pursued the densest aggregations of krill they could find, Barlow said.The researchers also found that during both warm and more typical ocean conditions the whales were more likely to feed in areas where the water was cooler. During the marine heat wave, when even the coolest water temperatures were higher than normal conditions, the whales still sought the coolest waters available for feeding.In this region, cooler water temperatures represent deeper water that was pushed toward the surface in a process called upwelling and tends to be nutrient-rich, Torres said.The nutrient-rich water supports aggregations of krill, which in turn provide sustenance for the blue whales. In their study, the researchers were able to bring all of the pieces of this trophic pathway together to describe the relationships between oceanography, krill and whales.As warmer ocean conditions become more frequent, this new knowledge can be used to inform and adjust spatial management of human activities in the region in an effort to reduce impacts on New Zealand blue whales, Torres said."Documenting information like this can really help us understand how to reduce threats to these animals," Torres said. "We need continued monitoring to understand how these whales will respond to both the changing climate and human impacts."
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Geography
| 2,020 |
May 27, 2020
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https://www.sciencedaily.com/releases/2020/05/200527105036.htm
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Volcanic eruptions reduce global rainfall
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Climate change is occurring all over the globe as 1°C increase in Earth's surface temperature has led to the sea level rise, abrupt melting of the Arctic sea ice, and the increase in extreme weather events such as heat waves, droughts, and floods. To accurately predict the anthropogenic climate changes under the increase in greenhouse gases, it is important to understand the effects of natural factors such as solar and volcanic activities. A recent study has shown how global precipitation decreases when volcanoes erupt in the tropics.
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Professor Seung-Ki Min and Dr. Seungmok Paik of Division of Environmental Science and Engineering at POSTECH and researchers from the French National Centre for Scientific Research, Swiss Federal Institute of Technology in Zurich, and University of Edinburgh have released new findings that the El Niño induced by volcanic eruptions plays a key role in the decrease in global precipitation. So far, studies have shown that volcanic activity reduces precipitation across the globe, but its specific mechanism had been unclear. These research results were recently published in Science Advances, a sister journal of Science.During the two to three years following Mount Pinatubo's eruption in 1991, the average global temperature fell by about 0.2 degrees. This is because the massive dust including sulfur dioxide emitted by the eruption reflected the light from the sun and blocked its heat from reaching the Earth's surface. Volcanic activities, along with this cooling effect, reduce the global terrestrial precipitation but its amplitude greatly varies depending on climate model simulations. For the first time, the joint research team confirmed that the main factor for the drop in precipitation after volcanic eruptions is the difference in El Niño's response.El Niño is a natural climate variability that occurs every three to eight years, with weakened trade winds in the equatorial Pacific Ocean and warmer sea surface temperatures in the equatorial eastern Pacific, causing extreme weather conditions across the globe including drought and heavy rains. Under El Niño's influence, precipitation reduction occurs especially in the global monsoon regions, including Southeast Asia, India, South Africa, Australia and northern South America.The team compared several climate model simulations and found that El Niño appeared in the year following a volcanic eruption in most models, with a significant drop in precipitation around the global monsoon region. In particular, the strength of El Niño was different for each simulation, and the stronger the El Niño, the more pronounced the reduction in precipitation occurred. The research team also found that the stronger the volcanic forcing and the greater the warm water volume in the western Pacific Ocean, a stronger El Niño developed, which in turn intensified the reduction in precipitation.These findings are expected to be used to identify the side effects of geoengineering techniques and to predict the climate of the later years. In particular, it suggests that if geoengineering techniques are used to reduce global warming by spraying sulfur dioxide -- the main component of volcanic ash -- in the lower stratosphere to imitate artificial volcanoes, they could produce unexpected side effect of changing the precipitation patterns across the globe.Professor Seung-Ki Min stated, "If geoengineering techniques are applied to mimic volcanoes and block sunlight, drought and water shortages may increase significantly in the monsoon regions -- home to two-thirds of the world's population."This research was supported by the Mid-career Researcher Program of the National Research Foundation of Korea.
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Geography
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May 27, 2020
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https://www.sciencedaily.com/releases/2020/05/200527105047.htm
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Airborne science discovers complex geomorphic controls on Bornean forests
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Tropical forests contain some of the most biodiverse and dynamic ecosystems in the world. Environmental conditions such as precipitation, temperature, and soils shape the biota of the landscape. This influence is especially noticeable when comparing the towering trees found in low elevation forests to the hardier, shorter ones found at the top of tropical mountains. Together, these factors create an ever-changing and heterogeneous ecosystem, with each niche harboring different species of uniquely adapted trees.
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Scientists have sought to understand the links between geology (the rock types that soils originate from), biogeochemistry (feedbacks between environmental conditions, nutrient cycling, and plants), biodiversity (the variety of life in an ecosystem), and biogeography (how trees are distributed across a landscape) to paint a more complete picture of how life coevolved with our planet. Now, in a new study published today in "We wanted to explore how long-term processes that shape the Earth's surface also act to control the organization of ecosystems across landscapes. Understanding these organizing processes requires the integration of concepts from across disciplines. The purpose of this study was to combine high-resolution airborne remote sensing datasets that contain information on both ecosystems and the morphology of landscapes, to understand how the two are interrelated on this iconic tropical mountain," said Dana Chadwick, lead author of the study.The study analyzed data from Mt. Kinabalu in Malaysian Borneo -- a 4,095-meter high mountain harboring a wide diversity of trees across topographically varied terrain. As tropical rains drench the mountain's surface, elevation differences between its shallow slopes and steep peaks create imbalances in soil erosion rates -- generally, the steeper the hill, the faster the rain rushes down its surface, taking soil with it. Soils carry nutrients needed by plants to grow, and erosion contributes to the distribution of these plant-required nutrients. Some areas become nutrient-rich and others become nutrient-poor, influencing the kinds of trees that can grow there. Adding to this dynamic process, some soil types are more or less prone to erosion than others depending upon their geological origins, and can also contain more nutrients plants need than others.To overcome limitations of previous studies conducted in tropical mountains at a local scale, the researchers used maps created by ASU's Global Airborne Observatory to collect large-scale data across 32 watersheds and at elevations ranging from 700 to 2800 meters. The maps included the concentrations of nutrients in the tropical forest canopy as well as the structure and architecture of the trees. This provided the researchers an unprecedented look at the forests of Mt. Kinabalu and its remote complex terrain."Although we originally deployed our airborne observatory to Borneo for conservation impact, such as the new protected area now under development, the opportunity to discover all-new patterns of biodiversity also presented itself in ultra-remote areas like Mt. Kinabalu," said Greg Asner, author of the study and director of ASU's Center for Global Discovery and Conservation Science.The chemical maps revealed that leaves from trees contained different amounts of nutrients depending upon both the elevation and geology of its environment. Along hillslopes, from ridge to valley, trees contain more nutrients while their ability to capture and utilize sunlight also increases. The researchers found that this trend was significantly impacted by changing erosion rates, highlighting the important role erosion plays in distributing fresh nutrients to the soil."The discovery of such strong and beautifully complex geologic control on forest composition gives us new insight into the fundamental make-up of Bornean forests, in ways that inspire even more exploration," Dr. Asner added.
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Geography
| 2,020 |
May 26, 2020
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https://www.sciencedaily.com/releases/2020/05/200526173836.htm
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Warming climate is changing where birds breed
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Spring is in full swing. Trees are leafing out, flowers are blooming, bees are buzzing, and birds are singing. But a recent study published in
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Clark Rushing, Assistant Professor in the Department of Wildland Resources and Ecology Center, Quinney College of Natural Resources at Utah State University, and colleagues at the U.S. Geological Survey wanted to know how climate change has already affected where birds breed. They used data from the Breeding Bird Survey -- one of the oldest and longest citizen-science programs in the world -- to conduct their research. "Thousands of devoted volunteers, cooperators, and a joint U.S.-Canadian wildlife management team have contributed to the success of the surveys for the last 54 years," said Andy Royle, a USGS senior scientists and co-author of the study. "The Breeding Bird Survey is fundamental to our understanding and management of wild bird populations in North America."The research team combined Breeding Bird Survey data with powerful computer models to discover changes in breeding range for 32 species of birds found in eastern North America. What they found is surprising:Some birds' ranges are expanding. Birds that both breed and winter in North America are extending their ranges north to take advantage of new, warm places to breed. These birds are also maintaining their southern ranges. These results bring hope that some bird populations, such as Carolina wrens and red-bellied woodpeckers, may be resilient to future climate change.Some birds' ranges are shrinking. Neotropical migratory birds breed in North America during the summer and migrate to the Caribbean, Central America, and South America for the winter. Neotropical migrants include many species that people love and look forward to seeing each spring such as buntings, warblers, orioles, and flycatchers. The team's research shows that these birds are not expanding north and their southern ranges are shrinking.To make matters worse, over the past 50 years Neotropical bird populations have decreased by about 2.5 billion individuals. Rushing explained, "There's a real risk that, if these declines continue at their current pace, many species could face extinction within this century. Neotropical migrants are vulnerable to future climate change, putting them at risk of greater declines."Neotropical migrants already fly thousands of miles each year to breed, so why can't they go just a bit farther as the climate warms? The researchers suspect the conditions where the birds live during the winter might make this impossible. Migrations require immense reserves of energy, so migratory birds need high-quality winter habitat with abundant food and moisture. Unfortunately, many habitats in the Caribbean, Central America, and South America are being degraded. It is possible that Neotropical birds can't store enough energy during the winter, so they simply can't extend their journeys any farther."That's just one explanation," concluded Rushing, "and it highlights how little we know and how much more research is needed." And what the team does know wouldn't have been possible without the help of devoted citizen scientists.
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Geography
| 2,020 |
May 26, 2020
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https://www.sciencedaily.com/releases/2020/05/200526161133.htm
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Mathematics can save lives at sea
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Hundreds of people die at sea every year due to vessel and airplane accidents. Emergency teams have little time to rescue those in the water because the probability of finding a person alive plummets after six hours. Beyond tides and challenging weather conditions, unsteady coastal currents often make search and rescue operations exceedingly difficult.
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New insight into coastal flows gleaned by an international research team led by George Haller, Professor of Nonlinear Dynamics at ETH Zurich, promises to enhance the search and rescue techniques currently in use. Using tools from dynamical systems theory and ocean data, the team has developed an algorithm to predict where objects and people floating in water will drift. "Our work has a clear potential to save lives," says Mattia Serra, former Ph.D. student at ETH and now a postdoctoral fellow at Harvard, who is the first author of a study recently published in In today's rescue operations at sea, elaborate models of ocean dynamics and weather forecasting are used to predict the path of drifting objects. For fast-changing coastal waters, however, such predictions are often inaccurate due to uncertain parameters and missing data. As a result, a search may be launched in the wrong location, causing a loss of precious time.Haller's research team obtained mathematical results predicting that objects floating on the ocean's surface should congregate along a few special curves which they call TRansient Attracting Profiles (TRAPs). These curves are invisible to the naked eye but can be extracted and tracked from instantaneous ocean surface current data using recent mathematical methods developed by the ETH team. This enables quick and precise planning of search paths that are less sensitive to uncertain-ties in the time and place of the accident.In collaboration with a team of MIT's Department of Mechanical Engineering, a group of the Woods Hole Oceanographic Institute and the US Coast Guard, the ETH team tested their new, TRAP-based search algorithm in two separate ocean experiments near Martha's Vineyard near the north-eastern coast of the United States. Working from the same real-time data available to the Coast Guard, the team successfully identified TRAPs in the region in real time. They found that buoys and manikins thrown in the water indeed quickly gathered along these evolving curves. "Of several competing approaches tested in this project, this was the only algorithm that consistently worked in situ," says Haller."Our results are rapidly obtained, easy to interpret and cheap to implement," points out Serra. He adds that the method they have developed also has the potential to predict the evolution of oil spills. The next plan of the research group is to test their new prediction tool in other ocean regions as well. As Haller stresses: "Our hope is that this method will become a standard part of the toolkit of coast guards everywhere."
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Geography
| 2,020 |
May 26, 2020
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https://www.sciencedaily.com/releases/2020/05/200526124038.htm
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Rarely heard narwhal vocalizations
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With the help of Inuit hunters, geophysicists recently recorded the various calls, buzzes, clicks and whistles of narwhals as they summered in a Greenland fjord. The recordings help scientists better understand the soundscape of Arctic glacial fjords and provide valuable insight into the behavior of these shy and mysterious creatures, according to the researchers.
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Narwhals are difficult to study because they are notoriously shy and skittish and spend most of their time deep in the freezing Arctic Ocean. They tend to summer in glacial fjords around Greenland and Canada, but scientists often have trouble getting close enough to study them. Glacier fronts can be dangerous and hard to access, and the animals tend to swim off when approached by motorized boats.But Inuit hunters familiar with the mysterious cetaceans can get closer to the animals without disturbing them. In July 2019, researchers accompanied several Inuit whale hunting expeditions in Northwest Greenland to study the narwhals that summer there in more detail.Using underwater microphones attached to small boats, the researchers captured narwhal social calls and foraging sounds, getting as close as 25 meters (82 feet) to the elusive cetaceans.The recordings help the researchers provide a baseline of the kinds of sounds that permeate the narwhals' pristine habitat. In combination with sightings, they also show narwhals get closer to glacier ice than previously thought for this area and the animals do forage for food in summer, contrary to some previous findings."Their world is the soundscape of this glacial fjord," said Evgeny Podolskiy, a geophysicist at Hokkaido University in Sapporo, Japan and lead author of a new study detailing the findings in AGU's Podolskiy and his colleagues had been working in Greenland fjords for several years, studying the sounds made by melting glaciers. Coincidentally, a population of narwhals summers in the fjords they were studying, and Podolskiy saw an opportunity to study the wily creatures."I realized working in the area and not paying attention to the elephant in the room -- the key endemic legendary Arctic unicorn just flowing around our glacier -- was a big mistake," he said.The researchers tagged along on several Inuit hunting expeditions departing from the village of Qaanaaq, placing microphones underwater and recording the baseline sounds of the fjord.They captured several types of sounds made by narwhals, including social calls, or whistles, and clicks used for echolocation, the biological sonar used by dolphins, bats, some whales and other animals to navigate and find food.The closer narwhals get to their food, the faster they click, until the noise becomes a buzz not unlike that of a chainsaw. This terminal buzz helps the narwhals pinpoint the location of their prey."If you approach and target these fast fish, you better know precisely where they are; you need to gather this information more frequently," Podolskiy said.Few studies have documented narwhals feeding in the summertime. Because the microphones picked up terminal buzz, a sound associated with finding food, the new study provides further evidence that narwhals do forage in summer.Surprisingly, the researchers found narwhals come roughly within 1 kilometer (half a mile) of a glacier calving front, despite the fact that these areas are some of the noisiest places in the ocean and calving icebergs can be dangerous."There is so much cracking due to ice fracturing and bubbles melting out... it's like a fizzy drink underwater," Podolskiy said. "It seems we are dealing with animals living in one of the most noisy environments without having much trouble with that."
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Geography
| 2,020 |
May 26, 2020
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https://www.sciencedaily.com/releases/2020/05/200526115042.htm
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Sugar turns brown algae into good carbon stores
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You may like them or not, but almost everyone knows them: brown algae such as Fucus vesiculosus, commonly known as bladderwrack, grow along the entire German coast. Giant kelp like Macrocystis or Sargassum grow closely together along the coasts but can also form floating aggregates that can cover the Atlantic from west to east. Some ecologists see this this very productive ecosystem as a marine counterpart to rainforests on land. In these algal forests, large amounts of carbon dioxide are stored, making them an important part of the global carbon cycle.
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Andreas Sichert from the Max Planck Institute for Marine Microbiology dedicated his PhD to the question how brown algae can be such a good sink of carbon: "Main constituents of algal biomass are their cell walls -- a tight network of proteins and long-chained sugars. When the algae die, we actually have little clue about the fate of algal biomass in the ocean, for example which compounds are degraded fast or slowly."The Atlantic coast is not a cozy habitat. Tides, wind and waves demand special adaptations from the inhabitants of this harsh environment. Brown algae developed a special cell wall structure, making them both firm and flexible, and enabling the plant to successfully withstand heavy currents and waves. A major component of the cell walls is the polysaccharide fucoidan, a long-chained sugar accounting for about a quarter of algal dry mass. Likely, fucoidan can regulate the water content of the cell wall which protects brown algae from drying out at low tide.What role this sugar plays in the long degradation process of brown algae was analyzed by scientists from the research group Marine Glycobiology at the Max Planck Institute for Marine Microbiology and the MARUM, Center for Marine Environmental Sciences at the University of Bremen. For their study, they cooperated with colleagues from the Massachusetts Institute of Technology, from the University of Greifswald and from the University of Vienna. "It was already known that microbial communities hydrolyze fucoidan slower than other algal polysaccharides and thus fucoidan might act as carbon sink" says Andreas Sichert from the Max Planck Institute for Marine Microbiology, first author of the study, published in the scientific journal So far, the fucoidan degradation pathways were only partially known, but it was evident that they involve a substantial number of enzymes either distributed within a microbial community or housed within individual, highly specialized bacteria. The scientists from Bremen examined the latter theory and analyzed newly isolated bacteria of the genus Lentimonas, belonging to the phylum Verrucomicrobia. Even the isolation of these Lentimonas bacteria was challenging. "From initially more than thousand colonies, only one was able to degrade fucoidan in the end," remembers Christopher H. Corzett from the Massachusetts Institute of Technology, first author of the study next to Andreas Sichert."We could show that Lentimonas acquired a remarkably complex machinery for the degradation of fucoidan that uses about one hundred enzymes to liberate the sugar fucose -- a part of fucoidan," says Jan-Hendrik Hehemann, leader of the research group Marine Glycobiology. "This is probably one of the most complicated biochemical degradation pathways for natural material that we know of." Fucose is then metabolized via a bacterial microcompartment, a proteinaceous shell that shields the cell from the toxic intermediate lactaldehyde. "The need for such a complex catabolic pathway underpins the recalcitrance of fucoidans for most marine bacteria and it shows that only highly specialized organisms in the ocean are able to break down this algal sugar," says Hehemann. "This can explain the slower turnover of the algal biomass in the environment and suggests that fucoidans sequester carbon in the ocean."Scientists are also interested in enzymes for fucoidan degradation because it may be a pharmacologically active molecule that shows similar effects to heparin in blood clotting. "Enzymes that specifically fragment fucoidan and thus help to characterize its structure are of great scientific interest because they enable researchers to understand the effects of fucoidan and to open up these marine sugars for biotechnological applications," says Thomas Schweder, participating microbiologist from the University of Greifswald.
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Geography
| 2,020 |
May 25, 2020
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https://www.sciencedaily.com/releases/2020/05/200525115648.htm
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There is no escaping from climate change, even in the deep sea
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Even though the deeper layers of the ocean are warming at a slower pace than the surface, animals living in the deep ocean are more exposed to climate warming and will face increasing challenges to maintain their preferred thermal habitats in the future.
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Reporting in the journal Despite rapid surface warming, the team found that global mean climate velocities in the deepest layers of the ocean (>1,000 m) have been 2 to nearly 4-fold faster than at surface over the second half of the 20th century. The authors point to the greater thermal homogeneity of the deep ocean environment as responsible for these larger velocities. Moreover, while climate velocities are projected to slow down under scenarios contemplating strong mitigation of greenhouse gas emissions (RCP2.6), they will continue to accelerate in the deep ocean."Our results suggest that deep sea biodiversity is likely to be at greater risk because they are adapted to much more stable thermal environments," says Jorge García Molinos, a climate ecologist at Hokkaido University's Arctic Research Center, who contributed to the study. "The acceleration of climate velocity for the deep ocean is consistent through all tested greenhouse gas concentration scenarios. This provides strong motivation to consider the future impacts of ocean warming to deep ocean biodiversity, which remains worryingly understudied."Climate velocities in the mesopelagic layer of the ocean (200-1000 m) are projected to be between 4 to 11 times higher than current velocities at the surface by the end of this century. Marine life in the mesopelagic layer includes great abundance of small fish that are food for larger animals, including tuna and squid. This could present additional challenges for commercial fisheries if predators and their prey further down the water column do not follow similar range shifts.The authors also compared resulting spatial patterns of contemporary climate velocity with those of marine biodiversity for over 20,000 marine species to show potential areas of risk, where high biodiversity and velocity overlap. They found that, while risk areas for surface and intermediate layers dominate in tropical and subtropical latitudes, those of the deepest layers are widespread across all latitudes except for polar regions.The scientists caution that while uncertainty of the results increases with depth, life in the deep ocean is also limited by many factors other than temperature, such as pressure, light or oxygen concentrations. "Without knowing if and how well deep ocean species can adapt to these changes, we recommend to follow a precautionary approach that limits the negative effects from other human activities such as deep-sea mining and fishing, as well as planning for climate-smart networks of large Marine Protected Areas for the deeper ocean," says García Molinos.
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Geography
| 2,020 |
May 25, 2020
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https://www.sciencedaily.com/releases/2020/05/200522095502.htm
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'Arks' of genetic diversity in terrestrial mammals
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Mapping the distribution of life on Earth, from genes to species to ecosystems, is essential in informing conservation policies and protecting biodiversity. Researchers from the University of Copenhagen and the University of Adelaide developed models based on long-standing evolutionary and ecological theories to explain and map genetic diversity globally, a basal, but up-to-now hidden dimension of biodiversity.
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Maximizing the protection of life on Earth requires knowledge of the global patterns of biodiversity at multiple dimensions, from genetic diversity within species, to species and ecosystem diversity. Yet, the lack of genetic sequences with geographic information at global scale has so far hindered our ability to map genetic diversity, an important, but hard to detect, biodiversity dimension.In a new study, researchers from the Universities of Copenhagen and Adelaide have collected and georeferenced a massive amount of genetic data for terrestrial mammals and evaluated long-standing theories that could explain the global distribution of genetic diversity. They found that regions of the world rich in deep evolutionary history, such as Northern Andes, the Eastern Arc Mountains, Amazonia, the Brazilian Atlantic forest, the central America jungles, sub-Saharan Africa and south-eastern Asia are also strongholds of genetic diversity. They also show that the relatively stable climate in these regions during the past 21'000 years contributes significantly to this intraspecific richness."Genetic diversity within species is a critical component of biodiversity, playing two important roles at the same time. It reflects species evolutionary history and defines their capacity to adapt under future environmental change. However, and despite the predictions of major biodiversity theories, the actual global distribution of genetic diversity remained, so far, a mystery. Recent collective efforts to populate public databases with genetic sequences and their localities allowed us to evaluate these theories and generate the first global maps of genetic diversity in terrestrial mammal assemblages," says Spyros Theodoridis, Postdoctoral Researcher at the Center for Macroecology, Evolution and Climate, GLOBE Institute, and lead author of the study."The tropics, and more specifically tropical mountain regions, host large amounts of the global pool of genetic diversity. These arks of biodiversity are under a high pressure today due to climate and land-use change. The conservation of genetic diversity in these areas should be a priority in on-going conservation efforts," says David Nogues-Bravo, the senior author of the study and Associate Professor at the University of Copenhagen.The study also evaluated the effects of climate change during the last 21'000 years in shaping current patterns of genetic diversity. Regions of the world that experienced less severe change in temperature and precipitation harbor higher levels of genetic diversity, potentially due to reduced population extinctions. It also suggests that past inter-annual precipitation variability contributes to higher genetic diversity possibly through population adaptive divergence."While we show that areas of high genetic diversity tend to occur in regions where climates have remained relatively unchanged during past periods of global-scale climate change, many of these regions are forecast to experience major climate disturbances in the near future. Unfortunately, this is likely to lead to a loss of genetic diversity in many biodiversity hotspots," says Damien Fordham, Associate Professor at The University of Adelaide's Environment Institute and a coauthor of the study."The identified correlations of genetic diversity with evolutionary history and past climate change allowed us to develop predictive models at global scale, particularly in regions that lack sufficient data, such as the tropics. These predictions constitute a first step towards filling major gaps of knowledge for genetic diversity, and can inform and be further validated by field-work campaigns in data-poor regions of the Earth," says Carsten Rahbek, head of the Center for Macroecology, Evolution and Climate.The study is supported by the Danish National Research Foundation and the Australian Research Council and is published in the scientific journal
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Geography
| 2,020 |
May 22, 2020
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https://www.sciencedaily.com/releases/2020/05/200522154555.htm
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Mississippi Delta marshes in a state of irreversible collapse
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Given the present-day rate of global sea-level rise, remaining marshes in the Mississippi Delta are likely to drown, according to a new Tulane University study.
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A key finding of the study, published in The loss of 2,000 square miles (5,000 kmThe study used hundreds of sediment cores collected since the early 1990s to examine how marshes responded to a range of rates of sea-level rise during the past 8,500 years."Previous investigations have suggested that marshes can keep up with rates of sea-level rise as high as half an inch per year (10 mm/yr), but those studies were based on observations over very short time windows, typically a few decades or less," said Torbjörn Törnqvist, lead author and Vokes Geology Professor in the Tulane Department of Earth and Environmental Sciences."We have taken a much longer view by examining marsh response more than 7,000 years ago, when global rates of sea-level rise were very rapid but within the range of what is expected later this century."The researchers found that in the Mississippi Delta most marshes drown in a few centuries once the rate of sea-level rise exceeds about one-tenth of an inch per year (3 mm/yr). When the rate exceeds a quarter of an inch per year (7.5 mm/yr), drowning occurs in about half a century."The scary thing is that the present-day rate of global sea-level rise, due to climate change, has already exceeded the initial tipping point for marsh drowning," Törnqvist said. "And as things stand right now, the rate of sea-level rise will continue to accelerate and put us on track for marshes to disappear even faster in the future."While these findings indicate that the loss of remaining marshes in coastal Louisiana is probably inevitable, there are still meaningful actions that can be taken to prevent the worst possible outcomes. The most important one, Törnqvist said, is to drastically curb greenhouse gas emissions to prevent sea-level rise from ramping up to rates where marshes will drown within a matter of decades.The other one is to implement major river diversions as quickly as possible, so at least small portions of the Mississippi Delta can survive for a longer time. However, the window of opportunity for these actions to be effective is rapidly closing, he said.
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Geography
| 2,020 |
May 22, 2020
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https://www.sciencedaily.com/releases/2020/05/200522095459.htm
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Indigenous collaboration and leadership key to managing sea otter population recovery
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A new study highlights the need to engage Indigenous communities in managing sea otter population recovery to improve coexistence between humans and this challenging predator.
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The sea otters' recovery along the northwest coast of North America presents a challenge for coastal communities because both otters and humans like to eat shellfish, such as sea urchins, crabs, clams and abalone. Expanding populations of sea otters and their arrival in new areas are heavily impacting First Nations and Tribes that rely on harvesting shellfish.SFU lead author Jenn Burt says the study focused beyond the challenges to seek solutions going forward. "We documented Indigenous peoples' perspectives which illuminated key strategies to help improve sea otter management and overall coexistence with sea otters."Most research focuses on how sea otter recovery greatly reduces shellfish abundance or expands kelp forests, rather than on how Indigenous communities are impacted, or how they are adapting to the returning sea otters' threat to their food security, cultural traditions, and livelihoods.Recognizing that Indigenous perspectives were largely absent from dialogues about sea otter recovery and management, SFU researchers reached out to initiate the Coastal Voices collaboration.Coastal Voices is a partnership with Indigenous leaders and knowledge holders representing 19 First Nations and Tribes from Alaska to British Columbia.Based on information revealed in workshops, interviews, and multiple community surveys, SFU researchers and collaborating Indigenous leaders found that human-otter coexistence can be enabled by strengthening Indigenous governance authority and establishing locally designed, adaptive co-management plans for sea otters.The study, published this week in "Our people actively managed a balanced relationship with sea otters for millennia," says co-author and Haida matriarch Kii'iljuus (Barbara Wilson), a recent SFU alumnus."Our work with Coastal Voices and this study helps show how those rights and knowledge need to be recognized and be part of contemporary sea otter management."Anne Salomon, a professor in SFU's School of Resource and Environmental Management, co-authored the study and co-led the Coastal Voices research partnership."This research reveals that enhancing Indigenous people's ability to coexist with sea otters will require a transformation in the current governance of fisheries and marine spaces in Canada, if we are to navigate towards a system that is more ecologically sustainable and socially just," says Salomon.Despite challenges, the authors say transformation is possible. They found that adaptive governance and Indigenous co-management of marine mammals exist in other coastal regions in northern Canada and the U.S. They suggest that increasing Indigenous leadership and Canadian government commitments to Reconciliation may provide opportunities for new approaches and more collaborative marine resource management.
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Geography
| 2,020 |
May 21, 2020
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https://www.sciencedaily.com/releases/2020/05/200521151926.htm
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Tracking the tinderbox: Stanford scientists map wildfire fuel moisture across western US
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As California and the American West head into fire season amid the coronavirus pandemic, scientists are harnessing artificial intelligence and new satellite data to help predict blazes across the region.
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Anticipating where a fire is likely to ignite and how it might spread requires information about how much burnable plant material exists on the landscape and its dryness. Yet this information is surprisingly difficult to gather at the scale and speed necessary to aid wildfire management.Now, a team of experts in hydrology, remote sensing and environmental engineering have developed a deep-learning model that maps fuel moisture levels in fine detail across 12 western states, from Colorado, Montana, Texas and Wyoming to the Pacific Coast.The researchers describe their technique in the August 2020 issue of According to the paper's lead author, Krishna Rao, a PhD student in Earth system science at Stanford, the model needs more testing to figure into fire management decisions that put lives and homes on the line. But it's already illuminating previously invisible patterns. Just being able to see forest dryness unfold pixel by pixel over time, he said, can help reveal areas at greatest risk and "chart out candidate locations for prescribed burns."The work comes at a time of growing urgency for this kind of insight, as climate change extends and intensifies the wildfire season -- and as the ongoing COVID-19 pandemic complicates efforts to prevent large fires through controlled burns, prepare for mass evacuations and mobilize first responders.Fire agencies today typically gauge the amount of dried-out, flammable vegetation in an area based on samples from a small number of trees. Researchers chop and weigh tree branches, dry them out in an oven and then weigh them again. "You look at how much mass was lost in the oven, and that's all the water that was in there," said Konings, an assistant professor of Earth system science in Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth). "That's obviously really laborious, and you can only do that in a couple of different places, for only some of the species in a landscape."The U.S. Forest Service painstakingly collects this plant water content data at hundreds of sites nationwide and adds them to the National Fuel Moisture Database, which has amassed some 200,000 such measurements since the 1970s. Known as live fuel moisture content, the metric is well established as a factor that influences wildfire risk. Yet little is known about how it varies over time from one plant to another -- or from one ecosystem to another.For decades, scientists have estimated fuel moisture content indirectly, from informed but unproven guesses about relationships between temperature, precipitation, water in dead plants and the dryness of living ones. According to Rao, "Now, we are in a position where we can go back and test what we've been assuming for so long -- the link between weather and live fuel moisture -- in different ecosystems of the western United States."The new model uses what's called a recurrent neural network, an artificial intelligence system that can learn to recognize patterns in vast mountains of data. The scientists trained their model using field data from the National Fuel Moisture Database, then put it to work estimating fuel moisture from two types of measurements collected by spaceborne sensors. One involves measurements of visible light bouncing off Earth. The other, known as synthetic aperture radar (SAR), measures the return of microwave radar signals, which can penetrate through leafy branches all the way to the ground surface."One of our big breakthroughs was to look at a newer set of satellites that are using much longer wavelengths, which allows the observations to be sensitive to water much deeper into the forest canopy and be directly representative of the fuel moisture content," said Konings, who is also a center fellow, by courtesy, at Stanford Woods Institute for the Environment.To train and validate the model, the researchers fed it three years of data for 239 sites across the American west starting in 2015, when SAR data from the European Space Agency's Sentinel-1 satellites became available. They checked its fuel moisture predictions in six common types of land cover, including broadleaf deciduous forests, needleleaf evergreen forests, shrublands, grasslands and sparse vegetation, and found they were most accurate -- meaning the AI predictions most closely matched field measurements in the National Fuel Moisture Database -- in shrublands.Rich with aromatic herbs like rosemary and oregano, and often marked by short trees and steep, rocky slopes, shrublands occupy as much as 45 percent of the American West. They're not only the region's biggest ecosystem, Rao said, "they are also extremely susceptible to frequent fires since they grow back rapidly." In California, fires whipped to enormous size by Santa Ana winds burn in a type of shrubland known as chaparral. "This has led fire agencies to monitor them intensively," he said.The model's estimates feed into an interactive map that fire agencies may eventually be able to use to identify patterns and prioritize control measures. For now, the map offers a dive through history, showing fuel moisture content from 2016 to 2019, but the same method could be used to display current estimates. "Creating these maps was the first step in understanding how this new fuel moisture data might affect fire risk and predictions," Konings said. "Now we're trying to really pin down the best ways to use it for improved fire prediction."
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Geography
| 2,020 |
May 21, 2020
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https://www.sciencedaily.com/releases/2020/05/200521151836.htm
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Tropical forests can handle the heat, up to a point
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Tropical forests face an uncertain future under climate change, but new research published in
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The world's tropical forests store a quarter-century worth of fossil fuel emissions in their trees alone. There are fears that global heating can reduce this store if tree growth reduces or tree death increases, accelerating climate change.An international research team measured over half a million trees in 813 forests across the tropics to assess how much carbon is stored by forests growing under different climatic conditions today.The team reveal that tropical forests continue to store high levels of carbon under high temperatures, showing that in the long run these forests can handle heat up to an estimated threshold of 32 degrees Celsius in daytime temperature.Yet this positive finding is only possible if forests have time to adapt, they remain intact, and if global heating is strictly limited to avoid pushing global temperatures into conditions beyond the critical threshold.Lead author Dr Martin Sullivan, from the University of Leeds and Manchester Metropolitan University, said: "Our analysis reveals that up to a certain point of heating tropical forests are surprisingly resistant to small temperature differences. If we limit climate change they can continue to store a large amount of carbon in a warmer world."The 32 degree threshold highlights the critical importance of urgently cutting our emissions to avoid pushing too many forests beyond the safety zone."For example, if we limit global average temperatures to a 2°C increase above pre-industrial levels this pushes nearly three-quarters of tropical forests above the heat threshold we identified. Any further increases in temperature will lead to rapid losses of forest carbon."Forests release carbon dioxide into the atmosphere when the amount of carbon gained by tree growth is less than that lost through tree mortality and decay.The study is the first to analyse long-term climate sensitivity based on direct observation of whole forests across the topics. The research suggests that over the long-term, temperature has the greatest effect on forest carbon stocks by reducing growth, with drought killing trees the second key factor.The researchers conclude that tropical forests have long-term capacity to adapt to some climate change, in part because of their high biodiversity as tree species better able to tolerate new climatic conditions grow well and replace less well-adapted species over the long-term.But maximizing this potential climate resilience depends on keeping forests intact.Co-author Professor Beatriz Marimon from the State University of Mato Grosso in Brazil studies some of the world's hottest tropical forests in central Brazil. She noted: "Our results suggest that intact forests are able to withstand some climate change. Yet these heat-tolerant trees also face immediate threats from fire and fragmentation."Achieving climate adaptation means first of all protecting and connecting the forests that remain."Professor Marimon notes the clear limits to adaptation. "The study indicates a heat threshold of 32 degrees Celsius in daytime temperature. Above this point tropical forest carbon declines more quickly with higher temperatures, regardless of which species are present."Each degree increase above this 32 degree threshold releases four-times as much carbon dioxide as would have been released below the threshold."The insights into how the world's tropical forests respond to climate were only possible with decades of careful fieldwork, often in remote locations. The global team of 225 researchers combined forests observations across South America (RAINFOR), Africa (AfriTRON) and Asia (T-FORCES). In each monitoring plot the diameter of each tree and its height was used to calculate how much carbon they stored. Plots were revisited every few years to see how much carbon was being taken in, and how long it was stored before trees died.To calculate changes in carbon storage required identifying nearly 10,000 tree species and over two million measurements of tree diameter, across 24 tropical countries. According to Professor Simon Lewis of the University of Leeds and University College London: "The amount of carbon absorbed and stored by forests is a crucial element in how the Earth responds to climate change.""The study underlines why long-term research collaboration is essential for understanding the effects of environmental change. Scientists need to work together more than ever, as monitoring the health of our planet's great tropical forests is vital for all of us."Cutting carbon emissions enough to keep forests within the safety zone will be very challenging. Study author Professor Oliver Phillips of the University of Leeds said: "Keeping our planet and ourselves healthy has never been more important. Right now, humanity has a unique opportunity to make the transition toward a stable climate."By not simply returning to 'business as usual' after the current crisis we can ensure tropical forests remain huge stores of carbon. Protecting them from climate change, deforestation and wildlife exploitation needs to be front and centre of our global push for biosecurity."Imagine if we take this chance to reset how we treat our Earth. We can keep our home cool enough to protect these magnificent forests -- and keep all of us safer."
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Geography
| 2,020 |
May 21, 2020
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https://www.sciencedaily.com/releases/2020/05/200521112619.htm
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Mysterious glowing coral reefs are fighting to recover
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A new study by the University of Southampton has revealed why some corals exhibit a dazzling colourful display, instead of turning white, when they suffer 'coral bleaching' -- a condition which can devastate reefs and is caused by ocean warming. The scientists behind the research think this phenomenon is a sign that corals are fighting to survive.
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Many coral animals live in a fragile, mutually beneficial relationship, a 'symbiosis' with tiny algae embedded in their cells. The algae gain shelter, carbon dioxide and nutrients, while the corals receive photosynthetic products to fulfil their energy needs. If temperatures rise just 1?C above the usual summer maximum, this symbiosis breaks down; the algae are lost, the coral's white limestone skeleton shines through its transparent tissue and a damaging process known as 'coral bleaching' occurs.This condition can be fatal to the coral. Once its live tissue is gone, the skeleton is exposed to the eroding forces of the environment. Within a few years, an entire coral reef can break down and much of the biodiversity that depends on its complex structure is lost -- a scenario which currently threatens the future of reefs around the world.However, some bleaching corals undergo an, until now, mysterious transformation -- emitting a range of different bright neon colours. Why this happens has now been explained by a team of scientists from the University of Southampton's Coral Reef Laboratory, who have published their detailed insights in the journal The researchers conducted a series of controlled laboratory experiments at the coral aquarium facility of the University of Southampton. They found that during colourful bleaching events, corals produce what is effectively a sunscreen layer of their own, showing itself as a colourful display. Furthermore, it's thought this process encourages the coral symbionts to return.Professor Jörg Wiedenmann, head of the University of Southampton's Coral Reef Laboratory explains: "Our research shows colourful bleaching involves a self-regulating mechanism, a so-called optical feedback loop, which involves both partners of the symbiosis. In healthy corals, much of the sunlight is taken up by the photosynthetic pigments of the algal symbionts. When corals lose their symbionts, the excess light travels back and forth inside the animal tissue -reflected by the white coral skeleton. This increased internal light level is very stressful for the symbionts and may delay or even prevent their return after conditions return to normal."However, if the coral cells can still carry out at least some of their normal functions, despite the environmental stress that caused bleaching, the increased internal light levels will boost the production of colourful, photoprotective pigments. The resulting sunscreen layer will subsequently promote the return of the symbionts. As the recovering algal population starts taking up the light for their photosynthesis again, the light levels inside the coral will drop and the coral cells will lower the production of the colourful pigments to their normal level."The researchers believe corals which undergo this process are likely to have experienced episodes of mild or brief ocean-warming or disturbances in their nutrient environment -- rather than extreme events.Dr. Cecilia D'Angelo, Lecturer of Molecular Coral Biology at Southampton, comments: "Bleaching is not always a death sentence for corals, the coral animal can still be alive. If the stress event is mild enough, corals can re-establish the symbiosis with their algal partner. Unfortunately, recent episodes of global bleaching caused by unusually warm water have resulted in high coral mortality, leaving the world's coral reefs struggling for survival."Dr. Elena Bollati, Researcher at the National University Singapore, who studied this subject during her PhD training at the University of Southampton, adds: "We reconstructed the temperature history of known colourful bleaching events around the globe using satellite imagery. These data are in excellent agreement with the conclusions of our controlled laboratory experiments, suggesting that colourful bleaching occurs in association with brief or mild episodes of heat stress."The scientists are encouraged by recent reports suggesting colourful bleaching has occurred in some areas of the Great Barrier Reef during the most recent mass bleaching there in March-April 2020. They think this raises the hope that at least some patches of the world's largest reef system may have better recovery prospects than others, but emphasise that only a significant reduction of greenhouse gases at a global scale and sustained improvement in water quality at a regional level can save coral reefs beyond the 21st century.
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Geography
| 2,020 |
May 20, 2020
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https://www.sciencedaily.com/releases/2020/05/200520191434.htm
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Ancient ocean oxygen levels associated with changing atmospheric carbon dioxide
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Why do carbon dioxide levels in the atmosphere wax and wane in conjunction with the warm and cold periods of Earth's past? Scientists have been trying to answer this question for many years, and thanks to chemical clues left in sediment cores extracted from deep in the ocean floor, they are starting to put together the pieces of that puzzle.
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Recent research suggests that there was enhanced storage of respired carbon in the deep ocean when levels of atmospheric carbon dioxide concentrations were lower than today's levels. But new research led by a Texas A&M University scientist has reached back even further, for the first time revealing insights into atmospheric carbon dioxide levels in the 50,000 years before the last ice age."One of the biggest unknowns about past climate is the cause of atmospheric carbon dioxide variability over global warm-cold cycles," said Franco Marcantonio, lead author of the study and professor and Jane and Ken R. Williams '45 Chair in the Department of Geology and Geophysics at Texas A&M. "Here we investigated the 'how' of varying carbon dioxide with the 'where' -- namely, the Eastern Equatorial Pacific Ocean, which is an important region of the world ocean where, today, significant carbon dioxide is exhaled into the atmosphere and the greatest rates phytoplankton growth are found."The National Science Foundation-funded research was recently published in To examine ancient carbon dioxide levels, Marcantonio and a team of researchers analyzed an ocean floor sediment core extracted from the deep Eastern Equatorial Pacific Ocean. The 10-meter long core spans about 180,000 years, and the chemistry of the layers of sediment provide scientists with a window into past climates. The chemical measurements they make serve as a proxy for oxygen levels of the deep sea.Measuring minute traces of uranium and thorium isotopes, the team was able to associate periods of increased storage of respired carbon (and low deep-sea oxygen levels) with periods of decreased global atmospheric carbon dioxide levels during the past 70,000 years."By comparing our high-resolution sediment record of deep-sea oxygenation in the Eastern Equatorial Pacific with other areas of the Pacific and Southern Ocean, we find that the Pacific Ocean, like the Southern Ocean, is a location for deep-ocean respired carbon storage during periods of decreased global atmospheric CO"Understanding the past dynamics of Earth's carbon cycle is of fundamental importance to informing and guiding societal policy-making in a warming world with increasing levels of atmospheric carbon dioxide."Co-authors of the study were Ryan Hostak, a former Texas A&M graduate student who earned his master's degree in geology in 2019; Jennifer E. Hertzberg, who received her Ph.D. in oceanography from Texas A&M in 2015 and is now a postdoctoral researcher in the Department of Earth, Ocean and Atmospheric Sciences at Old Dominion University; and Matthew W. Schmidt, associate professor of Ocean, Earth and Atmospheric Sciences at Old Dominion. Marcantonio and his colleagues designed the study, he and Hostak performed the isotope analyses, and the team interpreted the data."By performing similar studies in sediment covering a wider swath of the deep Pacific Ocean, we'll be able to spatially map the extent of this past deep pool of respired carbon," Marcantonio said, looking forward to future research.The study's radiogenic and trace element analyses were conducted in the College of Geosciences' R. Ken Williams Radiogenic Isotope Facility. The sediment core was extracted by Marcantonio and colleagues on an NSF-funded research cruise aboard the R/V Melville in 2010.
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Geography
| 2,020 |
May 20, 2020
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https://www.sciencedaily.com/releases/2020/05/200520124941.htm
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Hunting threatens one of the world's most amazing wildlife migrations
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As the world looks to tighten up the illegal capture of wildlife, migratory birds are being threatened by widespread and unsustainable hunting across the Asia-Pacific region.
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University of Queensland-led research has revealed that three quarters of migratory shorebird species in the region have been hunted since the 1970s.UQ PhD student Eduardo Gallo-Cajiao said the finding was deeply concerning, as these globetrotters were already under pressure from other human impacts."The Asia-Pacific is host to one of the most amazing animal migrations on earth," Mr Gallo-Cajiao said."Every year, hundreds of thousands of shorebirds, wetland-dependent species, breed across the Arctic and boreal regions, moving south to Southeast Asia, Australia, and New Zealand along a migration corridor known as the East Asian-Australasian Flyway."The Flyway spans 22 countries, through which 61 species of shorebirds complete their epic annual migrations some covering up to 25,000 km each year."But many of these fascinating birds are unfortunately declining, with several on the brink of extinction."Until now, habitat loss due to the expansion of coastal infrastructure had been identified as one of the main causes of their declines, particularly around the Yellow Sea region of China and the Korean peninsula, where many birds stop to rest and feed on their migrations."The scale and significance of hunting was unknown prior to this study, and it's clear that it's likely contributed to declines of migratory shorebirds in this region."The team worked for four years assembling all available evidence on hunting -- analysing hunting records from 14 countries, involving 46 species.But there are knowledge gaps, as they could not find data for eight countries.Currently, there are five shorebird species at high risk of extinction in this region, including the critically endangered spoon-billed sandpiper, of which fewer than 500 remain."Our study discovered that other threatened species that have been subject to hunting include the great knot, far eastern curlew, and spotted greenshank," Mr Gallo-Cajiao said.UQ's Professor Richard Fuller said managing hunting was complicated by the broad range of people involved, from recreational hunters to subsistence hunters and commercial traders."At least some hunting is driven by issues of food security, so sustainable development must be considered when developing alternatives for management," Professor Fuller said."There's no coordinated monitoring of how many shorebirds are taken annually across the region, which makes management really hard."Internationally coordinated approaches to address hunting are now underway, including through the UN Convention on Migratory Species, but these efforts need to be drastically ramped up to avoid extinctions and maintain healthy wildlife populations."Additional ground surveys and an international coordinated monitoring strategy are also urgently needed."
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Geography
| 2,020 |
May 20, 2020
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https://www.sciencedaily.com/releases/2020/05/200520084135.htm
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Climate change will turn coastal Antarctica green, say scientists
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Scientists have created the first ever large-scale map of microscopic algae as they bloomed across the surface of snow along the Antarctic Peninsula coast. Results indicate that this 'green snow' is likely to spread as global temperatures increase.
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The team, involving researchers from the University of Cambridge and the British Antarctic Survey, combined satellite data with on-the-ground observations over two summers in Antarctica to detect and measure the green snow algae. Although each individual alga is microscopic in size, when they grow en masse they turn the snow bright green and can be seen from space. The study is published today in the journal "This is a significant advance in our understanding of land-based life on Antarctica, and how it might change in the coming years as the climate warms," said Dr Matt Davey in the University of Cambridge's Department of Plant Sciences, who led the study. "Snow algae are a key component of the continent's ability to capture carbon dioxide from the atmosphere through photosynthesis."Blooms of green snow algae are found around the Antarctic coastline, particularly on islands along the west coast of the Antarctic Peninsula. They grow in 'warmer' areas, where average temperatures are just above zero degrees Celsius during the austral summer -- the Southern Hemisphere's summer months of November to February. The Peninsula is the part of Antarctica that experienced the most rapid warming in the latter part of the last century.The team found that the distribution of green snow algae is also strongly influenced by marine birds and mammals, whose excrement acts as a highly nutritious natural fertiliser to accelerate algal growth. Over 60% of blooms were found within five kilometres of a penguin colony. Algae were also observed growing near the nesting sites of other birds, including skuas, and areas where seals come ashore.The team used images from the European Space Agency's Sentinel 2 satellite taken between 2017 and 2019, and combined these with measurements they made on the ground in Antarctica at Ryder Bay, Adelaide Island, and the Fildes Peninsula, King George Island."We identified 1679 separate blooms of green algae on the snow surface, which together covered an area of 1.9 km2, equating to a carbon sink of around 479 tonnes per year" said Davey. Put into context this is the same amount of carbon emitted by about 875,000 average petrol car journeys in the UK.Almost two thirds of the green algal blooms were on small, low-lying islands with no high ground. As the Antarctic Peninsula warms due to rising global temperatures, these islands may lose their summer snow cover and with it their snow algae. However, in terms of mass, the majority of snow algae is found in a small number of larger blooms in the north of the Peninsula and the South Shetland Islands, in areas where they can spread to higher ground as low-lying snow melts."As Antarctica warms, we predict the overall mass of snow algae will increase, as the spread to higher ground will significantly outweigh the loss of small island patches of algae," said Dr Andrew Gray, lead author of the paper, and a researcher at the University of Cambridge and NERC Field Spectroscopy Facility, Edinburgh.Photosynthesis is the process in which plants and algae generate their own energy, using sunlight to capture carbon dioxide from the atmosphere and release oxygen. There are many different types of algae, from the tiny, single-celled species measured in this study, to large leafy species like giant kelp. The majority of algae live in watery environments, and when excess nitrogen and phosphorus are available they can multiply rapidly to create visible algal blooms.The researchers say that the total amount of carbon held in Antarctic snow algae is likely to be much larger because carbon dioxide is also taken up by other red and orange algae, which could not be measured in this study. They plan further work to measure these other algal blooms, and also to measure the blooms across the whole of Antarctica using a mixture of field work and satellite images.Antarctica is the world's southernmost continent, typically known as a frozen land of snow and ice. But terrestrial life can be abundant, particularly along its coastline, and is responding rapidly to climate changes in the region. Mosses and lichens form the two biggest visible groups of photosynthesising organisms, and have been the most studied to date. This new study has found that microscopic algae also play an important role in Antarctica's ecosystem and its carbon cycling.
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Geography
| 2,020 |
May 19, 2020
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https://www.sciencedaily.com/releases/2020/05/200519204116.htm
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Migratory secrets of recovering whale species
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Scientists have discovered where a whale species that feeds around the sub-Antarctic island of South Georgia breeds during the winter months. This understanding of where the animals migrate from will enable conservation efforts for their recovery from years of whaling. The results are published this week (20 May 2020) in the
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Southern right whales were hunted to near extinction after centuries of whaling. In the most comprehensive study of its kind, 30 researchers from 11 countries studied 15 skin samples from whales feeding around the sub-Antarctic island of South Georgia and compared them to 149 samples collected from around Argentina and Brazil and South Africa where the whales breed and give birth to their calves. New samples were collected from South Georgia during an expedition led by the British Antarctic Survey in 2018 and were combined with samples held by a network of collaborators across the globe.Using a new genetic tool, the team discovered that most of the animals visiting South Georgia were calved around South America and not South Africa. This had previously been suspected, but not confirmed.Lead author Dr Emma Carroll, from University of Auckland says: "Genetic methods are important in linking whale breeding grounds, areas that are closely monitored for population recovery, with feeding areas that are being and will be impacted by climate change. It is only by understanding these links that we can understand how whale populations will fare in a changing world."Collaborating with Chilean colleagues, the team also analysed the first ever DNA sample from the Critically Endangered Chile-Peru southern right whale population. They found genetically, the Chile-Peru whale is a mixture between Indo-Pacific and Atlantic calving grounds, suggesting Chile-Peru has acted as a 'stepping stone' between these two areas.Whale ecologist and senior author Dr Jennifer Jackson, at British Antarctic Survey, who led the project, says: "This is an important part of the jigsaw in understanding the geographical range of southern right whales. Identifying the migratory links of recovering whale populations is crucial to build accurate assessments of how well whale populations are recovering, and to understand how vulnerable these populations are to anthropogenic threats through their life cycle."There have been unexplained high whale calf mortalities around Argentina in the Península Valdéz region over the last 17 years, so there is a lot of work to be done to protect this species throughout their migratory range."The team are also tracking the movements of two South Georgia right whales in real time using satellite tags. One whale is already migrating towards the South American coast, providing further evidence of the migratory connection. Follow these whales here:
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Geography
| 2,020 |
May 19, 2020
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https://www.sciencedaily.com/releases/2020/05/200519165851.htm
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But it's a dry heat: Climate change and the aridification of North America
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Discussions of drought often center on the lack of precipitation. But among climate scientists, the focus is shifting to include the growing role that warming temperatures are playing as potent drivers of greater aridity and drought intensification.
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Increasing aridity is already a clear trend across the western United States, where anthropogenic climate warming is contributing to declining river flows, drier soils, widespread tree death, stressed agricultural crops, catastrophic wildfires and protracted droughts, according to the authors of a Commentary article published online May 19 in At the same time, human-caused warming is also driving increased aridity eastward across North America, with no end in sight, according to climate scientists Jonathan Overpeck of the University of Michigan and Bradley Udall of Colorado State University."The impact of warming on the West's river flows, soils, and forests is now unequivocal," write Overpeck, dean of the U-M School for Environment and Sustainability, and Udall, senior water and climate scientist at Colorado State. "There is a clear longer-term trend toward greater aridification, a trend that only climate action can stop."The Commentary article responds to a PNAS paper, published May 11 by Justin Martin of the U.S. Geological Survey and his colleagues, that showed how warming is causing streamflow declines in the northern Rocky Mountains, including the nation's largest river basin, the Missouri.The Martin The study details the mechanisms of temperature-driven streamflow declines, and it "places more focus on how anthropogenic climate warming is progressively increasing the risk of hot drought and more arid conditions across an expanding swath of the United States," according to Overpeck and Udall.The Martin But that's a faulty assumption, one that ignores mounting evidence all around us, according to Overpeck and Udall."Anthropogenic climate change calls this assumption into question because we now know with high confidence that continued emissions of greenhouse gases into the atmosphere guarantees continued warming, and that this continued warming makes more widespread, prolonged and severe dry spells and droughts almost a sure bet," they write. "Greater aridity is redefining the West in many ways, and the costs to human and natural systems will only increase as we let the warming continue."Anticipated impacts in the Upper Missouri River Basin mirror changes already occurring in the Southwest, where the trend toward warming-driven aridification is clearest.Rivers in the Southwest provide the only large, sustainable water supply to more than 40 million people, yet flows have declined significantly since the late 20th century. Declining flows in the region's two most important rivers, the Colorado and the Rio Grande, have been attributed in part to increasing temperatures caused by human activities, most notably the burning of fossil fuels.Multiple processes tied to warming are likely implicated in the observed aridification of the West, according to Overpeck and Udall. For starters, warmer air can hold more water vapor, and this thirsty air draws moisture from water bodies and land surfaces through evaporation and evapotranspiration -- further drying soils, stressing plants and reducing streamflow.But the atmosphere's increased capacity to hold water vapor also boosts the potential for precipitation; rain and snow amounts are, in fact, rising in many regions of the United States outside the Southwest. However, the frequency and intensity of dry spells and droughts are expected to increase across much of the continent in coming decades, even if average annual precipitation levels rise, according to Overpeck and Udall."Perhaps most troubling is the growing co-occurrence of hot and dry summer conditions, and the likely expansion, absent climate change action, of these hot-dry extremes all the way to the East Coast of North America, north deep into Canada, and south into Mexico," they write."Other parts of North America likely won't see the widespread aridification and decadal to multi-decadal droughts of the West, but will nonetheless continue to see more frequent and severe arid events -- extreme dry spells, flash droughts and interannual droughts will become part of the new normal," according to Overpeck and Udall."Unfortunately, climate change and this aridification are likely irreversible on human time scales, so the sooner emissions of greenhouse gases to the atmosphere are halted, the sooner the aridification of North America will stop getting worse."
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Geography
| 2,020 |
May 19, 2020
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https://www.sciencedaily.com/releases/2020/05/200519140425.htm
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Sustainable palm oil? How environmental protection and poverty reduction can be reconciled
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Palm oil is often associated with tropical deforestation above all else. However, this is only one side of the story, as agricultural scientists from the University of Göttingen and the IPB University Bogor (Indonesia) show in a new study. The rapid expansion of oil palm has also contributed considerably to economic growth and poverty reduction in local communities, particularly in Asia. The study was published in the
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For the study, the researchers evaluated results from over 30 years of research on the environmental, economic and social consequences of oil palm cultivation in Africa, Asia and Latin America. They combined the results from the international literature with their own data from Indonesia, which they have been collecting since 2012 as part of an interdisciplinary German-Indonesian Collaborative Research Centre (CRC 990). Indonesia is the largest palm oil producer and exporter in the world. A large proportion of the palm oil produced in Indonesia is exported to Europe and the USA, where it is used by the food, fuel and cosmetics industries.The research data show that the expansion of oil palm in some regions of the world -- especially Indonesia and Malaysia -- contributes significantly to tropical deforestation and the loss of biodiversity. Clearing forestland also leads to substantial carbon emissions and other environmental problems. "However, banning palm oil production and trade would not be a sustainable solution," says Professor Matin Qaim, agricultural economist at the University of Göttingen and first author of the study. "The reason is that oil palm produces three times more oil per hectare than soybean, rapeseed, or sunflower. This means that if palm oil was replaced with alternative vegetable oils, much more land would be needed for cultivation, with additional loss of forests and other natural habitats."Banning palm oil would also have negative economic and social consequences in the producing countries. "It is often assumed that oil palm is only grown on large industrial plantations," says Qaim. "In reality, however, around half of the world's palm oil is produced by smallholder farmers. Our data show that oil palm cultivation increases profits and incomes in the small farm sector, in addition to raising wages and creating additional employment for rural labourers. Although there are incidents of conflicts over land, overall the oil palm boom has significantly reduced rural poverty in Indonesia and other producing countries.""The goal should be to make palm oil production more environmentally and climate-friendly," says Professor Ingo Grass, agricultural ecologist at the University of Hohenheim and co-author of the study. "High yields on the already-cultivated land are important, in order to reduce additional deforestation. Mosaic landscapes, where oil palm is combined with patches of forest and other crops in agroforestry systems, could also help to protect biodiversity and ecosystem functions," he adds.The authors conclude that developing and implementing more sustainable production systems are challenges which require both innovative research and policymaking. Clearly and fairly defined land rights and improved access for smallholder farmers to training, credit and modern technologies would be important steps forward. Consumers can contribute by shopping for food, fuel, and cosmetics more consciously and avoiding waste wherever possible.
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Geography
| 2,020 |
May 19, 2020
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https://www.sciencedaily.com/releases/2020/05/200519090321.htm
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Ambitious EU climate efforts could increase emissions in the rest of the world
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The EU has an ambition of being climate neutral in 2050. It is hoped that this can be achieved through a green transition in the energy sector and CO
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However, should the EU implement its most ambitious decarbonization agenda, while the rest of the world continues with the status quo, non-EU nations will end up emitting more greenhouse gases, thereby significantly offsetting the reductions of EU emissions. This is the conclusion of a new policy brief prepared by economics experts at the University of Copenhagen's Department of Food and Resource Economics.For every tonne of CO"Obviously, the EU's own climate footprint will be significantly reduced. But the EU's economy is intertwined with the rest of the world through trade relations, which would change as we implement a green transition in our energy sector, industries and ways of life. Part of the emissions that Europe "saves" through an extensive green transition could possibly be 'leaked' to the rest of the world through, among other things, trade mechanisms, depending on the climate policy of other countries," according to economist and brief co-author Professor Wusheng Yu, of the University of Copenhagen's Department of Food and Resource Economics."If the world beyond the EU does not follow suit and embark on a similar green transition, the decline in global greenhouse gas emissions will effectively be limited and well below the level agreed upon in EU climate policy," adds co-author, economist and Yu's department fellow, Francesco Clora.In the most ambitious 2050 scenario as calculated by the EUCalc model, the EU pulls all of the green levers for production and consumption in various sectors, including the industrial and energy sectors.In this scenario, a green transformation of COSimilarly, a phase-out of fossil fuels by the EU would lower global demand, thus making them cheaper. In response, non-EU countries would be likely to import and consume larger quantities of fossil fuels.Finally, more climate-friendly consumer behaviour in the EU could end up pushing part of the saved COShould Europe simply throw in the towel and drop its high ambitions for a better global climate? Certainly not. But we must make sure not to go it alone. Professor Wusheng Yu explains:"A green transition in the EU alone cannot significantly reduce global COTherefore, Professor Yu says that it is essential for the EU to formulate green strategies for each sector and every member state, while taking these economic mechanisms into account and carefully evaluating their impact, when it comes to encouraging other countries to pursue similar decarbonization strategies.
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Geography
| 2,020 |
May 18, 2020
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https://www.sciencedaily.com/releases/2020/05/200518145013.htm
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Ocean warming's impact on Antarctic krill
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Ocean warming is likely to alter the distribution and lifecycle of ecologically and commercially important Antarctic krill over the rest of this century, according to new IMAS-led research.
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Published in the journal The research team found there would be a moderate impact across 85 percent of the Southern Ocean, with krill expected to move further south and shifts in the time of year when conditions are most favourable.The research was led by IMAS PhD student Devi Veytia and included scientists from the Australian Antarctic Division, ACE CRC and the British Antarctic Survey.Ms Veytia said the study's findings included a projected change in the seasonal distribution of krill habitat, particularly around northerly fishing grounds near the Antarctic Peninsula."Understanding how krill will respond to climate change and the ecological impacts of those changes is important to both conservation efforts and the management of the fishery, the largest in the Southern Ocean."Our study combined projections of sea surface temperatures and phytoplankton using climate change scenarios with an established krill growth model."We found that over the coming decades krill habitat quality can be expected to improve in spring, particularly further south and on the continental shelf."In summer, there was little net change, but good habitat redistributed, increasing at high and low latitudes and declining in mid-latitudes."Autumn saw the greatest decline in habitat quality and area, mainly in sub-Antarctic regions."In response, we expect krill habitat to move south into higher latitudes."At the same time there will be a change in the time of year when krill habitat is optimal, improving in spring, but declining in important regions during summer and autumn."Ms Veytia said the shift in seasonal habitat quality, especially around the Antarctic Peninsula, could disturb the synchronisation between krill and the annual cycle of this important ecosystem."Synchronisation usually allows krill to capitalize on seasonally available food sources, allowing growth, reproduction and storing of reserves to survive the winter."A temporal shift in habitat quality could create a timing mismatch, potentially affecting krill reproduction and population dynamics."The commercial fishery, which is currently centred on the Antarctic Peninsula and south Scotia Sea, could also be affected, leading to shifts in the distribution and timing of the fishing effort."The geographical shift of krill habitat towards more southerly waters is also likely to have ecosystem impacts, particularly for land-based predators at sub-Antarctic islands that have limited capacity to follow their preferred food source," she said.
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Geography
| 2,020 |
April 16, 2021
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https://www.sciencedaily.com/releases/2021/04/210416143037.htm
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Hidden magma pools pose eruption risks that we can't yet detect
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Volcanologists' ability to estimate eruption risks is largely reliant on knowing where pools of magma are stored, deep in the Earth's crust. But what happens if the magma can't be spotted?
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Shane Rooyakkers, a postdoctoral scholar at GNS Science in New Zealand, grew up in the shadow of Mount Taranaki on the country's North Island, hiking on the island's many volcanoes. Today, his research is revealing hidden dangers that may have been beneath his feet all along.A new study, published yesterday in Rooyakkers, who is lead author on the study and completed the work while at McGill University, compared the composition of the quenched magma, which had formed smooth volcanic glass, with rocks from an eruption from that same volcano, Krafla, in 1724. Before his study, scientists thought the shallow magma they'd drilled into had been emplaced after a series of eruptions in the 1980s. No one expected the hidden magma to be related to the 1724 eruption, so what Rooyakkers found was a surprise."When we looked at the compositions from 1724, we found an almost perfect match for what was sampled during the drilling," Rooyakkers says. "That suggests that actually, this magma body has been there since 1724 and has previously been involved in an eruption at Krafla. So that raises the question of, 'Why did geophysics not pick it up?'"The answer is size. Most magma detection relies on seismic imaging, like oil companies use to detect reserves deep under the seafloor. When there's an earthquake, the instruments detect how long it takes for sound waves to travel through the crust. Depending on the density of the rocks, the soundwaves return at different times. So if there's water, oil, or magma stored underground, the soundwaves should reflect it. But these hidden magma chambers are too small for these instruments, as well as other detection tools, to find."In traditional approaches to volcano monitoring, a lot of emphasis is placed on knowing where magma is and which magma bodies are active," says Rooyakkers. "Krafla is one of the most intensely-monitored and instrumented volcanoes in the world. They've thrown everything but the kitchen sink at it in terms of geophysics. And yet we still didn't know there was this rhyolitic magma body sitting at just two kilometers' depth that's capable of producing a hazardous eruption."Studies like Rooyakkers' suggest that smaller, more widely-distributed magma bodies might be more common than previously thought, challenging the conventional view that most eruptions are fed from larger and deeper magma chambers that can be reliably detected.Beyond not being able to monitor magmatic activity, planning for eruptions and estimating risks becomes more difficult if scientists suspect that hidden magma bodies could be present. For example, the Krafla volcano is usually dominated by basalt, a type of magma that tends to erupt passively (like the recent eruption at Fagradallsfjall in Iceland) rather than in an explosion. But the hidden magma body at Krafla is made of rhyolite, a magma type that often creates violent explosions when it erupts."So the concern in this case would be that you have a shallow rhyolitic magma that you don't know about, so it hasn't been considered in hazards planning," Rooyakkers explains. "If it's hit by new magma moving up, you might have a much more explosive eruption than you were anticipating."As volcanologists become aware of the hazards associated with these shallow, distributed magma systems, they can work on improving monitoring, trying to capture these hidden magma pools. Covering a volcanic area in more detectors may be costly, but by improving the resolution of magma imaging, scientists may save a community or company far more than the cost of the study. The risks vary from volcano to volcano, but in general, as we learn more about these magma systems, scientists concerned with estimating hazards can be aware of the possibility of hidden magma.Despite the risks he's uncovering, will Rooyakkers still live around volcanoes?"Oh yeah, for sure," he says with a laugh. "I mean, there's risk with anything, isn't there?"
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Geology
| 2,021 |
April 16, 2021
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https://www.sciencedaily.com/releases/2021/04/210416120019.htm
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A rich marine algal ecosystem 600 million years earlier than previously thought
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The first photosynthetic oxygen-producing organisms on Earth were cyanobacteria. Their evolution dramatically changed the Earth allowing oxygen to accumulate into the atmosphere for the first time and further allowing the evolution of oxygen-utilizing organisms including eukaryotes. Eukaryotes include animals, but also algae, a broad group of photosynthetic oxygen-producing organisms that now dominate photosynthesis in the modern oceans. When, however, did algae begin to occupy marine ecosystems and compete with cyanobacteria as important phototrophic organisms?
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In a new study Zhang et al use the molecular remains of ancient algae (so-called biomarkers) to show that algae occupied an important role in marine ecosystems 1400 million years ago, some 600 million years earlier than previously recognized.The specific biomarkers explored by Zhang et al are a group of sterane molecules derived from sterols that are prominent components of cell membranes in eukaryotic organisms. A particular difficulty in analyzing for ancient steranes is that samples are easily contaminated with steranes from other sources. The sources of contamination range from steranes introduced during the sampling, transport and processing of the samples, to geological contamination of steranes as fluids have flow through the rocks.Zhang et al carefully controlled for each of the sources of contamination and found, as have others, that no steranes were liberated when using standard protocols to extract biomarkers from such ancient rocks, in this case the 1400 million-year-old Xiamaling Formation in North China.However, Shuichang Zhang, the lead author of the study speculated that "There is some fossil evidence for eukaryotic algae 1400 million years ago, or even earlier, so we wondered whether any steranes in these rocks might be more tightly bound to the kerogens and not easily released during standard biomarker extraction." Therefore, Zhang et al utilized a stepwise heating protocol where samples were slowly heated in gold tubes in 9 steps from 300°C to 490°C. The organic molecules liberated in each of the nine steps were extracted and steranes indicating the presence of both red and green algae were liberated, especially at the higher temperatures.Zhang continues "Many will be concerned that the steranes we found were a product of some kind of contamination. We were also worried about this, but we ran in parallel samples that have been heated to high temperatures during their geologic history and that, therefore, contained no biomarkers. We found no steranes in these. This means that our protocols were clean, and we are therefore confident that the steranes we found were indigenous to the rock."It's still not completely clear why the steranes were so tightly bound to the kerogen and not released during standard protocols. But, the findings of Zhang et al. show that both green and red algal groups were present in marine ecosystems by 1400 million years ago. This is 600 million years earlier than evident from previous biomarker studies. This work shows that the red and green algal lineages had certainly evolved by 1400 million years ago, and this should be a useful constraint in timing the overall history of eukaryote evolution. This work also shows that at least some ancient marine ecosystems functioned more similarly to modern ecosystems than previously thought, at least with respect to the types of photosynthetic organisms producing organic matter. This means furthermore that there was sufficient nutrients and oxygen available to drive the presence of algae-containing ecosystems.Professor Don Canfield, Nordic Center for Earth Evolution, University of Southern Denmark, a co-author on the study adds: "We hope that our study will inspire others to utilize similar techniques to better unravel the full history of eukaryote evolution through geologic time."
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Geology
| 2,021 |
April 8, 2021
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https://www.sciencedaily.com/releases/2021/04/210408131503.htm
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More than 5,000 tons of extraterrestrial dust fall to Earth each year
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Every year, our planet encounters dust from comets and asteroids. These interplanetary dust particles pass through our atmosphere and give rise to shooting stars. Some of them reach the ground in the form of micrometeorites. An international program conducted for nearly 20 years by scientists from the CNRS, the Université Paris-Saclay and the National museum of natural history with the support of the French polar institute, has determined that 5,200 tons per year of these micrometeorites reach the ground. The study will be available in the journal
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Micrometeorites have always fallen on our planet. These interplanetary dust particles from comets or asteroids are particles of a few tenths to hundredths of a millimetre that have passed through the atmosphere and reached the Earth's surface.To collect and analyse these micrometeorites, six expeditions led by CNRS researcher Jean Duprat have taken place over the last two decades near the Franco-Italian Concordia station (Dome C), which is located 1,100 kilometres off the coast of Adélie Land, in the heart of Antarctica. Dome C is an ideal collection spot due to the low accumulation rate of snow and the near absence of terrestrial dust.These expeditions have collected enough extraterrestrial particles (ranging from 30 to 200 micrometres in size), to measure their annual flux, which corresponds to the mass accreted on Earth per square metre per year.If these results are applied to the whole planet, the total annual flux of micrometeorites represents 5,200 tons per year. This is the main source of extraterrestrial matter on our planet, far ahead of larger objects such as meteorites, for which the flux is less than ten tons per year.A comparison of the flux of micrometeorites with theoretical predictions confirms that most micrometeorites probably come from comets (80%) and the rest from asteroids.This is valuable information to better understand the role played by these interplanetary dust particles in supplying water and carbonaceous molecules on the young Earth.
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Geology
| 2,021 |
April 8, 2021
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https://www.sciencedaily.com/releases/2021/04/210408112415.htm
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Asteroid crater on Earth provides clues about Martian craters
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The almost 15-million-year-old Nördlinger Ries is an asteroid impact crater filled with lake sediments. Its structure is comparable to the craters currently being explored on Mars. In addition to various other deposits on the rim of the basin, the crater fill is mainly formed by stratified clay deposits. Unexpectedly, a research team led by the University of Göttingen has now discovered a volcanic ash layer in the asteroid crater. In addition, the team was able to show that the ground under the crater is sinking in the long term, which provides important insights for the exploration of craters on Mars, such as the ancient Gale and Jezero crater basin lakes, currently being explored by the NASA Curiosity and Perseverance Rovers. The results of the study have been published in the
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Until now, it was assumed that these lake deposits had settled on a stable crater floor. The same is assumed for crater deposits on Mars, although some of them show significantly inclined sediment strata. The layers of these crater fills appear on the surface as ring-shaped structures. However, a precise understanding of the underlying conditions and the temporal interrelationships of the deposits is important for reconstructing the chemical development of a crater lake and habitability for possible lifeforms that might have developed there in the past.For the first time, the researchers have now been able to detect a volcanic ash layer in the lake sediments of the 330-metre-thick crater filling in the Ries. "This is surprising, as volcanic rocks were not expected here since the circular basin was identified as an asteroid crater," says first author Professor Gernot Arp from the Geosciences Centre at the University of Göttingen. "The ash was blown in from a volcano 760 kilometres further east in Hungary. The age of the ash can be dated to 14.2 million years ago," adds his colleague and co-author István Dunkl.The ash, which in the meantime has transformed into nitrogen-rich silicate minerals, reveals a surprisingly strong bowl-shaped geometry: at the edge of the basin the ash is found at the current ground surface, while in the centre of the basin it comes to rest at a depth of about 220 metres. A subsequent systematic evaluation of drillings and geological mapping has now also revealed an arrangement of concentric rings -- the "outcropping strata" -- for the Ries crater filling, with the oldest deposits at the rim and the most recent in the centre.Calculations show that this bedding geometry cannot be explained solely by the fact that the underlying lake sediments are settling. In fact, an additional subsidence of about 135 metres had to be accounted for. This can only be explained by subsidence phenomena of the crater bedrock, which is fractured kilometres deep. While further research is needed to explain the exact mechanisms of this subsidence of the crater floor, a simple model calculation can already show that subsidence of this magnitude is basically possible due to settlement phenomena of the fractured underground rocks. This means that inclined strata in the fillings of craters on Mars can now be better explained, at least for craters that show a close timely association of crater formation, flooding by water, and sedimentation.The study was funded by the German Research Foundation (DFG). In addition to geobiologists and sedimentologists from the University of Göttingen, the Bavarian Environment Agency, and Brown University, Providence, USA, were also involved.
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Geology
| 2,021 |
February 8, 2019
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https://www.sciencedaily.com/releases/2019/02/190208115314.htm
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Researchers help define Southern Ocean's geological features
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New data collected by University of Wyoming researchers and others point to a newly defined mantle domain in a remote part of the Southern Ocean.
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UW Department of Geology and Geophysics Professor Ken Sims and recent Ph.D. graduate Sean Scott are co-authors of an article, "An isotopically distinct Zealandia-Antarctic mantle domain in the Southern Ocean," published by the scientific journal "The Australian-Antarctic Ridge is the remotest mid-ocean ridge in the world's oceans and one of the last explored ridge segments, and, lo and behold, our isotope measurements of the samples we collected provided us with quite a surprise -- an entirely new domain in the Earth's mantle," Sims says.The two were part of a group investigating the Australian-Antarctic Ridge (AAR) that included researchers from the United States, South Korea and France. Known as the last gap in the mapping and sampling of seafloor spreading centers, AAR is a 1,200-mile expanse in the most remote parts of the ocean ridge system. Specifically, the team was looking to resolve questions surrounding the boundaries of Earth's mantle domains as seen in ocean basalt formations created during mantle melting.Those basalt formations are pushed up from the Earth's mantle beneath the Indian and Pacific oceans through the ridges and have distinct isotopic compositions. That has created a long-accepted boundary at the Australian-Antarctic Discordance along the Southeast Indian Ridge. This boundary has been widely used to place constraints on large-scale patterns of the mantle flow and composition in the Earth's upper mantle. However, sampling between the Indian and Pacific ridges was lacking, because of difficulty in obtaining samples.Now, Sims, Scott and company present data from the region that show the ridge has isotopic compositions distinct from both the Pacific and Indian mantle domains. The data define a separate Zealandia-Antarctic domain that appears to have formed in response to the deep mantle upwelling and ensuing volcanism that led to the breakup of ancient supercontinent Gondwana around 90 million years ago. The Zealandia-Antarctic domain currently persists at the margins of the Antarctic continent.The group surmises that the relatively shallow depths of the AAR may be the result of this deep mantle upwelling, and large offset transformations to the east may be its boundary with the Pacific domain.
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Geology
| 2,019 |
February 8, 2019
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https://www.sciencedaily.com/releases/2019/02/190208085855.htm
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Life thrived on Earth 3.5 billion years ago, research suggests
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Three and a half billion years ago Earth hosted life, but was it barely surviving, or thriving? A new study carried out by a multi institutional team with leadership including the Earth-Life Science Institute (ELSI) of Tokyo Institute of Technology (Tokyo Tech) provides new answers to this question. Microbial metabolism is recorded in billions of years of sulfur isotope ratios that agree with this study's predictions, suggesting life throve in the ancient oceans. Using this data, scientists can more deeply link the geochemical record with cellular states and ecology.
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Scientists want to know how long life has existed on Earth. If it has been around for almost as long as the planet, this suggests it is easy for life to originate and life should be common in the Universe. If it takes a long time to originate, this suggests there were very special conditions that had to occur. Dinosaurs, whose bones are presented in museums around the world, were preceded by billions of years by microbes. While microbes have left some physical evidence of their presence in the ancient geological record, they do not fossilize well, thus scientists use other methods for understanding whether life was present in the geological record.Presently, the oldest evidence of microbial life on Earth comes to us in the form of stable isotopes. The chemical elements charted on the periodic are defined by the number of protons in their nuclei, for example, hydrogen atoms have one proton, helium atoms have two, carbon atoms contain six. In addition to protons, most atomic nuclei also contain neutrons, which are about as heavy as protons, but which don't bear an electric charge. Atoms which contain the same number of protons, but variable numbers of neutrons are known as isotopes. While many isotopes are radioactive and thus decay into other elements, some do not undergo such reactions; these are known as "stable" isotopes. For example, the stable isotopes of carbon include carbon 12 (written as 12C for short, with 6 protons and 6 neutrons) and carbon 13 (13C, with 6 protons and 7 neutrons).All living things, including humans, "eat and excrete." That is to say, they take in food and expel waste. Microbes often eat simple compounds made available by the environment. For example, some are able to take in carbon dioxide (COBesides carbon there are other chemical elements essential for living things. For example, sulfur, with 16 protons, has three naturally abundant stable isotopes, 32S (with 16 neutrons), 33S (with 17 neutrons) and 34S (with 18 neutrons). Sulfur isotope patterns left behind by microbes thus record the history of biological metabolism based on sulfur-containing compounds back to around 3.5 billion years ago. Hundreds of previous studies have examined wide variations in ancient and contemporary sulfur isotope ratios resulting from sulfate (a naturally occurring sulfur compound bonded to four oxygen atoms) metabolism. Many microbes are able to use sulfate as a fuel, and in the process excrete sulfide, another sulfur compound. The sulfide "waste" of ancient microbial metabolism is then stored in the geological record, and its isotope ratios can be measured by analyzing minerals such as the FeS2 mineral pyrite.This new study reveals a primary biological control step in microbial sulfur metabolism, and clarifies which cellular states lead to which types of sulfur isotope fractionation. This allows scientists to link metabolism to isotopes: by knowing how metabolism changes stable isotope ratios, scientists can predict the isotopic signature organisms should leave behind. This study provides some of the first information regarding how robustly ancient life was metabolizing. Microbial sulfate metabolism is recorded in over a three billion years of sulfur isotope ratios that are in line with this study's predictions, which suggest life was in fact thriving in the ancient oceans. This work opens up a new field of research, which ELSI Associate Professor Shawn McGlynn calls "evolutionary and isotopic enzymology." Using this type of data, scientists can now proceed to other elements, such as carbon and nitrogen, and more completely link the geochemical record with cellular states and ecology via an understanding of enzyme evolution and Earth history.
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Geology
| 2,019 |
February 7, 2019
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https://www.sciencedaily.com/releases/2019/02/190207102621.htm
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Unusual microbes hold clues to early life
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A new study has revealed how a group of deep-sea microbes provides clues to the evolution of life on Earth, according to a recent paper in
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Called Hydrothermarchaeota, this group of microbes lives in such an extreme environment that they have never been cultivated in a laboratory for study. A research team from Bigelow Laboratory for Ocean Sciences, the University of Hawai'i at Manoa, and the Department of Energy Joint Genome Institute bypassed the problem of cultivation with genetic sequencing methods called genomics, a suite of novel techniques used to sequence large groups of genetic information. They found that Hydrothermarchaeota may obtain energy by processing carbon monoxide and sulfate, which is an overlooked metabolic strategy. The microbes use energy from this process to grow as a form of chemosynthesis."The majority of life on Earth is microbial, and most microbes have never been cultivated," said Beth Orcutt, a senior research scientist at Bigelow Laboratory and one of the study's senior authors. "These findings emphasize why single cell genomics are such important tools for discovering how a huge proportion of life functions."Analyzing Hydrothermarchaeota genomes revealed that these microbes belong to the group of single-celled life known as archaea and evolved early in the history of life on Earth -- as did their unusual metabolic processes. These observations suggest that the subsurface ocean crust is an important habitat for understanding how life evolved on Earth, and potentially other planets.The researchers also found genetic evidence that Hydrothermarchaeota have the ability to move on their own. Motility offers a valuable survival strategy for the extreme environment they call home, which has a limited supply of nutrients essential to life."Studying these unique microbes can give us insights into both the history of Earth and the potential strategies of life on other planets," said Stephanie Carr, first author on the paper and a former postdoctoral researcher with Orcutt who is now an assistant professor at Hartwick College. "Their survival strategies make them incredibly versatile, and they play an important, overlooked role in the subsurface environments where they live."In 2011, Orcutt and other project scientists sailed to the flank of the Juan de Fuca Ridge, a mid-ocean ridge off the coast of Washington where two ocean plates are separating and generating new oceanic crust. They used Woods Hole Oceanographic Institution's deep-diving robot Jason to travel 2.6 km to the seafloor and collect samples of the fluid that flows through the deep crust.These crustal fluids contained microbes that had never before been studied. Working in partnership with the Department of Energy Joint Genome Institute, the researchers sorted and analyzed the microbes in the Single Cell Genomics Center at Bigelow Laboratory. This cutting-edge research facility is directed by Ramunas Stepanauskas, a senior research scientist and study author. The project team also analyzed the microbes using metagenomics, a technique that extracts genomic information directly from environmental samples. These analyses yielded insights into the genetic blueprints of Hydrothermarchaeota, their relationship to other archaea, and the strategies they have evolved to survive in the subseafloor.The researchers will build upon this discovery when they return to the Juan de Fuca Ridge in May 2019 to continue investigating the extreme microbes thriving below the seafloor. Orcutt will lead a cruise using ROV Jason with this team of researchers to further explore the subseafloor environment, leveraging funding from the National Science Foundation and NASA."The microbes living 'buried alive' below the seafloor are really intriguing to us, since they can survive on low amounts of energy," Orcutt said. "We hope that our experiments on these weird microbes can show how they do this, so we can imagine how life might exist on other planets."
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Geology
| 2,019 |
February 6, 2019
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https://www.sciencedaily.com/releases/2019/02/190206131936.htm
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Fate of the subducted oceanic crust revealed by laboratory experiments
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Professor Tetsuo Irifune of the Geodynamics Research Center (GRC) of Ehime University heads a research group investigating the Earth's interior by means of experiments at extreme pressures and temperatures, simulating those expected in the deepest regions of our planet.
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Using a combination of ultrasonic techniques and a large volume press apparatus, GRC researchers were successful in measuring the sound velocities of CaSiO3 perovskite (CaPv), an important mineral of the mantle at depths below 560 km. This result allowed them to directly interpret seismic observations by a comparison with their velocity profiles obtained in the laboratory, and derived some composition models for the regions across the 660 km depth discontinuity that marks the boundary between the upper and lower mantle.The scientific article that presents their results was published on January 10 in the journal CaPv constitutes 7-10 vol% of the pyrolitic mantle and up to 30 vol% of subducted basaltic rocks below ~560 km depth and therefore is an important constituent mineral in both the mantle transition region (MTR; 410-660 km in depth) and lower mantle (660-2900 km in depth). CaPv also plays an important role in immobilizing heavy elements such as rare earth elements or actinides in the mantle due to its large calcium site, which can easily accommodate such large elements. But despite such importance, no measurements of sound velocities have been made CaPv at high temperatures, because this phase is unstable at ambient conditions and hence there was no adequate sample for such measurements."Because CaPv is only stable at pressure and temperature conditions of the mantle, we designed an experiment that allows us to synthesize this phase with the adequate shape and dimension under high pressure, then subsequently send an acoustic wave directly into the pressurized sample. Using this new approach, we can study high-pressure minerals, which are not stable at atmospheric conditions, such as CaPv." says Steeve Gréaux, the researcher leading this project.Professor Irifune and his team already demonstrated in 2008, that pyrolite, a hypothetical rock composition derived as a mixture of basalt and peridotite agree well with geophysical observations at depths down to 560 km, which was also reported in "We did find that the cubic form of CaPv, which is most likely to be present in the mantle, has lower velocities than what was formerly predicted by theoretical studies. This result refutes previous models that proposed formation of CaPv in pyrolite could explain the steep velocity gradient above a depth of 660 km. On the other hand, it is in good agreement with a former study proposing the presence of basalts beneath a depth of 660 km on the basis of density measurements." says Tetsuo Irifune.These new results indeed show that the presence of subducted oceanic crust can explain the magnitude of the reduction of shear velocity below a depth of 660 km, as observed beneath North America. Incidentally, the model they proposed is very consistent with the recent discovery, in 2018, of CaPv in a natural diamond, which provides evidence for the presence of oceanic crust material in the uppermost lower mantle. It is also compatible with global-scale geodynamics calculations that predicted basalt enrichment beneath 660 km would stabilize the subducted slab in this region.The authors conclude "CaPv, which was once called "invisible" in the lower mantle as this phase was predicted to have velocities similar to those of the most abundant mineral (MgSiO3 perovskite or bridgmanite) in fact holds velocities substantially lower than those of bridgmanite at depths of 660-800 km, which should greatly contribute to tracing the existence and recycling of the former oceanic crust in the Earth's lower mantle.."
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Geology
| 2,019 |
February 6, 2019
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https://www.sciencedaily.com/releases/2019/02/190206115635.htm
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2018 fourth warmest year in continued warming trend, according to NASA, NOAA
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Earth's global surface temperatures in 2018 were the fourth warmest since 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA).
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Global temperatures in 2018 were 1.5 degrees Fahrenheit (0.83 degrees Celsius) warmer than the 1951 to 1980 mean, according to scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. Globally, 2018's temperatures rank behind those of 2016, 2017 and 2015. The past five years are, collectively, the warmest years in the modern record."2018 is yet again an extremely warm year on top of a long-term global warming trend," said GISS Director Gavin Schmidt.Since the 1880s, the average global surface temperature has risen about 2 degrees Fahrenheit (1 degree Celsius). This warming has been driven in large part by increased emissions into the atmosphere of carbon dioxide and other greenhouse gases caused by human activities, according to Schmidt.Weather dynamics often affect regional temperatures, so not every region on Earth experienced similar amounts of warming. NOAA found the 2018 annual mean temperature for the contiguous 48 United States was the 14th warmest on record.Warming trends are strongest in the Arctic region, where 2018 saw the continued loss of sea ice. In addition, mass loss from the Greenland and Antarctic ice sheets continued to contribute to sea level rise. Increasing temperatures can also contribute to longer fire seasons and some extreme weather events, according to Schmidt."The impacts of long-term global warming are already being felt -- in coastal flooding, heat waves, intense precipitation and ecosystem change," said Schmidt.NASA's temperature analyses incorporate surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations.These raw measurements are analyzed using an algorithm that considers the varied spacing of temperature stations around the globe and urban heat island effects that could skew the conclusions. These calculations produce the global average temperature deviations from the baseline period of 1951 to 1980.Because weather station locations and measurement practices change over time, the interpretation of specific year-to-year global mean temperature differences has some uncertainties. Taking this into account, NASA estimates that 2018's global mean change is accurate to within 0.1 degree Fahrenheit, with a 95 percent certainty level.NOAA scientists used much of the same raw temperature data, but with a different baseline period and different interpolation into Earth's polar and other data poor regions. NOAA's analysis found 2018 global temperatures were 1.42 degrees Fahrenheit (0.79 degrees Celsius) above the 20th century average.NASA's full 2018 surface temperature data set -- and the complete methodology used to make the temperature calculation -- are available at:GISS is a laboratory within the Earth Sciences Division of NASA's Goddard Space Flight Center in Greenbelt, Maryland. The laboratory is affiliated with Columbia University's Earth Institute and School of Engineering and Applied Science in New York.
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Geology
| 2,019 |
February 5, 2019
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https://www.sciencedaily.com/releases/2019/02/190205204102.htm
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Scientists study organization of life on a planetary scale
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When we think of life on Earth, we might think of individual examples ranging from animals to bacteria. When astrobiologists study life, however, they have to consider not only individual organisms, but also ecosystems, and the biosphere as a whole.
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In astrobiology, there is an increasing interest in whether life as we know it is a quirk of the particular evolutionary history of the Earth or, instead, if life might be governed by more general organizing principles.If general principles exist that can explain properties common to all life on Earth, scientists hypothesize, then they may be universal to all life, even life on other planets. If a "universal biology" exists, it would have important implications for the search for life beyond Earth, for engineering synthetic life in the lab, and for solving the origin of life, enabling scientists to predict at least some properties of alien life.Previous research in this area has primarily focused on specific levels of organization within biology such as individual organisms or ecological communities. These levels form a hierarchy where individuals are composed of interacting molecules and ecosystems are composed of interacting individuals.An interdisciplinary team of researchers at Arizona State University (ASU) has gone beyond focusing on individual levels in this hierarchy to study the hierarchy itself, focusing on the biosphere as a whole. The results of their study have been recently published "To understand the general principles governing biology, we must understand how living systems organize across levels, not just within a given level," says lead author Hyunju Kim of ASU's Beyond Center and the School of Earth and Space Exploration.Through this study, the team found that biochemistry, both at the level of organisms and ecosystems, is governed by general organizing principles. "This means there is a logic to the planetary-scale organization of biochemistry," says co-lead author Harrison Smith of ASU's School of Earth and Space Exploration. "Scientists have talked about this type of logic for a long time, but until now they have struggled to quantify it. Quantifying it can help us constrain the way that life arises on a planet."For this research, the team constructed biochemical networks using a global database of 28,146 annotated genomes and metagenomes and 8,658 catalogued biochemical reactions. In so doing, they uncovered scaling laws governing biochemical diversity and network structure that are shared across levels of organization from individuals to ecosystems, to the biosphere as a whole."Quantifying general principles of life -- not restricted to a domain on the tree of life, or a particular ecosystem -- is a challenge," says Smith. "We were able to do that by combining tools from network science and scaling theory, while simultaneously leveraging large genomic datasets that researchers have been cataloging."The research team, led by Kim and Smith under supervision of Sara Walker of the ASU School of Earth and Space Exploration and the Beyond Center, also includes Cole Mathis of the Beyond Center and the ASU Department of Physics (now at the University of Glasgow), and Jason Raymond of the School of Earth and Space Exploration."Understanding the organizing principles of biochemistry at a global scale better enables us to understand how life operates as a planetary process," says Walker. "The ability to more rigorously identify universal properties of life on Earth will also provide astrobiologists with new quantitative tools to guide our search for alien life -- both in the lab on other worlds."
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Geology
| 2,019 |
February 5, 2019
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https://www.sciencedaily.com/releases/2019/02/190205102540.htm
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Volcanic growth 'critical' to the formation of Panama
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It is a thin strip of land whose creation kick-started one of the most significant geological events in the past 60 million years.
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Yet for scientists the exact process by which the Isthmus of Panama came into being still remains largely contentious.In a new study published today in the journal The Isthmus of Panama is a narrow piece of land that lies between the Caribbean Sea and the Pacific Ocean and links North and South America. It is believed to have fully formed around 2.8m years ago, yet scientists are still unsure about the processes and timescales that led up to this.Up until now researchers have favoured a model in that the Isthmus of Panama was created through the collision of two of Earth's tectonic plates -- the South American Plate and the Caribbean Plate -- which pushed underwater volcanoes up from the sea floor and eventually forced some areas above sea level.However, new geochemical and geochronological data taken from the Panama Canal and field investigation of old volcanoes in this area have provided evidence that there was significant volcanic activity taking place during a critical phase of the emergence of the Isthmus of Panama around 25 million years ago.The growth of volcanoes in the Panama Canal area is thought to have been particularly significant for the formation of the Isthmus because the Canal was constructed in a shallow area of Panama, which is believed to have remained underwater for the major part of the geological history of the region.This suggests that the formation of the volcanoes along the Canal could have played an important role in the rise of the Isthmus above sea level.Scientists are keen to discover exactly how the Isthmus of Panama formed given its significant role in shaping both weather patterns and biodiversity across the world.Before a landmass existed between North and South America, water had moved freely between the Atlantic and Pacific oceans, but this changed when Panama formed, forcing warm Caribbean waters northwards to form what we now know as the Gulf Stream, thus creating much warmer climates in north-western Europe.The formation of the Isthmus of Panama also played a major role in Earth's biodiversity, making it easier for animals and plants to migrate between the continents. In North America, the opossum, armadillo and porcupine all trace back to ancestors that came across the land bridge from South America. Likewise, the ancestors of bears, cats, dogs, horses, llamas, and raccoons all made the trek south across the Isthmus of Panama.Lead author of the study Dr David Buchs, from Cardiff University's School of Earth and Ocean Sciences, said: "The formation of the Isthmus of Panama is without doubt one of the most significant geological events to have happened on Earth, particularly because of its role in shaping large scale weather patterns, creating the Arctic ice cap and triggering widespread biodiversity across continents."We've provided evidence to show that volcanic activity was critical to the formation of the Isthmus of Panama and responsible for many of the geological features that we see around the region to this day."
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Geology
| 2,019 |
February 2, 2019
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https://www.sciencedaily.com/releases/2019/02/190202171847.htm
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Novel hypothesis goes underground to predict future of Greenland ice sheet
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The Greenland ice sheet melted a little more easily in the past than it does today because of geological changes, and most of Greenland's ice can be saved from melting if warming is controlled, says a team of Penn State researchers.
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"There is geologic data that suggests the ice sheet was more sensitive to warming and temperature variations in the past million years, and not so much in the more recent past," said David Pollard, research professor in the Earth and Environmental Systems Institute at Penn State.Too much warming will cause Greenland to lose most or all of its ice over the coming centuries, but most research indicates that the threshold warmth for complete ice loss has not been reached yet.Paleoclimatic records indicate that most of Greenland was ice-free within the last 1.1 million years even though temperatures then were not much warmer than conditions today. To explain this, the researchers point to there being more heat beneath the ice sheet in the past than today.Data show that when the Iceland hot spot -- the heat source that feeds volcanoes on Iceland -- passed under north-central Greenland 80 to 35 million years ago, it left molten rock deep underground but did not break through the upper mantle and crust to form volcanoes as it had in the west and east. The Earth's climate then was too warm for Greenland to have an ice sheet, but once it cooled the ice sheet formed, growing and shrinking successive with ice ages."The idea is that the loading and unloading, flexing and unflexing from ice ages tapped into slightly melted rock that was left deep under Greenland by the Iceland hot spot and brought that melt up," said Richard Alley, Evan Pugh University Professor of Geosciences at Penn State.Changes to the ice sheet allowed the molten rock to move closer to the Earth's surface, even to the base of the ice. The hotter bed melted more ice from below, lubricating the ice sheet so it was thinner and easier to melt from above.The melted rock wants to come up, according to Alley. As the ice sheet grows and shrinks, it essentially shakes the melt, drawing it up in pulses."The first shakes usually do the most moving," Alley said.The effect would have been largest when the first big ice sheet grew and then shrank, he added. More recent changes to the ice sheet also affect geothermal fluxes, but not as much as they had in the past."The hypothesis does not change the reality that if we make it hot, Greenland's ice melts, and no one will like that," Alley said. "It does not even really tell us whether geology just at this moment is making it harder or easier for the ice to melt. The ability of the ice to melt got easier in the past and is sort of bumpily getting harder, and we do not know where on the bumps we are."Pollard tested the team's hypothesis using a numerical, three-dimensional ice-sheet model. The researchers report their results in the "The Greenland ice sheet is very likely to melt a lot and retreat, and contribute to sea level in the next few centuries," Pollard said. "This study is part of the puzzle of figuring out how much it will melt and retreat. We are using past geologic data to validate the models that are being used for the future."If Greenland's ice sheet were to completely melt today, global sea levels would rise nearly 23 feet and flood coastal areas. Parts of cities like New York would be underwater. The team says future studies should integrate geologic and geophysical data as well as glaciological, atmospheric, oceanic and paleoclimatic information to better project how much and how fast the ice sheet will melt and its effect on sea-level rise."If you had a better idea of how much and how fast sea level rises from warming, you could make wiser decisions," Alley said. "This research is a piece of the effort to provide policymakers and planners with the background information that will allow them to make good decisions."
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Geology
| 2,019 |
February 1, 2019
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https://www.sciencedaily.com/releases/2019/02/190201114135.htm
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How predatory plankton created modern ecosystems after 'Snowball Earth'
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Around 635 to 720 million years ago, during Earth's most severe glacial period, Earth was twice almost completely covered by ice, according to current hypotheses. The question of how life survived these 'Snowball Earth' glaciations, lasting up to about 50 million years, has puzzled scientists for many decades. An international team, led by Dutch and German researchers of the Max Planck Society, now found the first detailed glimpse of life after the 'Snowball' in the form of newly discovered ancient molecules, buried in old rocks.
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"All higher animal life forms, including us humans, produce cholesterol. Algae and bacteria produce their own characteristic fat molecules," says first author Lennart van Maldegem from Max Planck Institute (MPI) for Biogeochemistry, who recently moved to the Australian National University in Canberra, Australia. "Such fat molecules can survive in rocks for millions of years, as the oldest (chemical) remnants of organisms, and tell us now what type of life thrived in the former oceans long ago."But the fossil fats the researchers recently discovered in Brazilian rocks, deposited just after the last Snowball glaciation, were not what they suspected. "Absolutely not," says team-leader Christian Hallmann from MPI for Biogeochemistry. "We were completely puzzled, because these molecules looked quite different from what we've ever seen before!"Using sophisticated separation techniques, the team managed to purify minuscule amounts of the mysterious molecule and identify its structure by nuclear magnetic resonance in the NMR department of Christian Griesinger at Max Planck Institute for Biophysical Chemistry. "This is highly remarkable itself," according to Klaus Wolkenstein from MPI for Biophysical Chemistry and the Geoscience Centre of the University of Göttingen. "Never has a structure been elucidated with such a small amount of such an old molecule." The structure was chemically identified as 25,28-bisnorgammacerane -- abbreviated as BNG, as van Maldegem suggests.Yet the origin of the compound remained enigmatic. "We of course looked if we could find it elsewhere," says van Maldegem, who then studied hundreds of ancient rock samples, with rather surprising success. "In particular the Grand Canyon rocks really were an eye-opener," says Hallmann. Although nowadays mostly sweltering hot, these rocks had also been buried under kilometres of glacial ice around 700 million years ago. Detailed additional analyses of molecules in Grand Canyon rocks -- including presumed BNG-precursors, the distribution of steroids and stable carbon isotopic patterns -- led the authors to conclude that the new BNG molecule most likely derives from heterotrophic plankton, marine microbes that rely on consuming other organisms for gaining energy. "Unlike for example green algae that engage in photosynthesis and thus belong to autotrophic organisms, these heterotrophic microorganisms were true predators that gained energy by hunting and devouring other algae and bacteria," according to van Maldegem.While predation is common amongst plankton in modern oceans, the discovery that it was so prominent 635 million years ago, exactly after the Snowball Earth glaciation, is a big deal for the science community. "Parallel to the occurrence of the enigmatic BNG molecule we observe the transition from a world whose oceans contained virtually only bacteria, to a more modern Earth system containing many more algae. We think that massive predation helped to 'clear' out the bacteria-dominated oceans and make space for algae," says van Maldegem. The resulting more complex feeding networks provided the dietary requirements for larger, more intricate lifeforms to evolve -- including the lineages that all animals, and eventually we humans, derive from. The massive onset of predation probably played a crucial role in the transformation of our planet and its ecosystems to its present state.
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Geology
| 2,019 |
January 31, 2019
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https://www.sciencedaily.com/releases/2019/01/190131125919.htm
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Earth's largest extinction event likely took plants first
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Little life could endure the Earth-spanning cataclysm known as the Great Dying, but plants may have suffered its wrath long before many animal counterparts, says new research led by the University of Nebraska-Lincoln.
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About 252 million years ago, with the planet's continental crust mashed into the supercontinent called Pangaea, volcanoes in modern-day Siberia began erupting. Spewing carbon and methane into the atmosphere for roughly 2 million years, the eruption helped extinguish about 96 percent of oceanic life and 70 percent of land-based vertebrates -- the largest extinction event in Earth's history.Yet the new study suggests that a byproduct of the eruption -- nickel -- may have driven some Australian plant life to extinction nearly 400,000 years before most marine species perished."That's big news," said lead author Christopher Fielding, professor of Earth and atmospheric sciences. "People have hinted at that, but nobody's previously pinned it down. Now we have a timeline."The researchers reached the conclusion by studying fossilized pollen, the chemical composition and age of rock, and the layering of sediment on the southeastern cliffsides of Australia. There they discovered surprisingly high concentrations of nickel in the Sydney Basin's mud-rock -- surprising because there are no local sources of the element.Tracy Frank, professor and chair of Earth and atmospheric sciences, said the finding points to the eruption of lava through nickel deposits in Siberia. That volcanism could have converted the nickel into an aerosol that drifted thousands of miles southward before descending on, and poisoning, much of the plant life there. Similar spikes in nickel have been recorded in other parts of the world, she said."So it was a combination of circumstances," Fielding said. "And that's a recurring theme through all five of the major mass extinctions in Earth's history."If true, the phenomenon may have triggered a series of others: herbivores dying from the lack of plants, carnivores dying from a lack of herbivores, and toxic sediment eventually flushing into seas already reeling from rising carbon dioxide, acidification and temperatures.One of three married couples on the research team, Fielding and Frank also found evidence for another surprise. Much of the previous research into the Great Dying -- often conducted at sites now near the equator -- has unearthed abrupt coloration changes in sediment deposited during that span.Shifts from grey to red sediment generally indicate that the volcanism's ejection of ash and greenhouse gases altered the world's climate in major ways, the researchers said. Yet that grey-red gradient is much more gradual at the Sydney Basin, Fielding said, suggesting that its distance from the eruption initially helped buffer it against the intense rises in temperature and aridity found elsewhere.Though the time scale and magnitude of the Great Dying exceeded the planet's current ecological crises, Frank said the emerging similarities -- especially the spikes in greenhouse gases and continuous disappearance of species -- make it a lesson worth studying."Looking back at these events in Earth's history is useful because it lets us see what's possible," she said. "How has the Earth's system been perturbed in the past? What happened where? How fast were the changes? It gives us a foundation to work from -- a context for what's happening now."The researchers detailed their findings in the journal The National Science Foundation and the Swedish Research Council funded the team's work.
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Geology
| 2,019 |
January 31, 2019
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https://www.sciencedaily.com/releases/2019/01/190131104930.htm
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Ancient asteroid impacts played a role in creation of Earth's future continents
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The heavy bombardment of terrestrial planets by asteroids from space has contributed to the formation of the early evolved crust on Earth that later gave rise to continents -- home to human civilisation.
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More than 3.8 billion years ago, in a time period called the Hadean eon, our planet Earth was constantly bombarded by asteroids, which caused the large-scale melting of its surface rocks. Most of these surface rocks were basalts, and the asteroid impacts produced large pools of superheated impact melt of such composition. These basaltic pools were tens of kilometres thick, and thousands of kilometres in diameter."If you want to get an idea of what the surface of Earth looked like at that time, you can just look at the surface of the Moon which is covered by a vast amount of large impact craters," says Professor Rais Latypov from the School of Geosciences of the University of the Witwatersrand in South Africa.The subsequent fate of these ancient, giant melt sheet remains, however, highly debatable. It has been argued that, on cooling, they may have crystallized back into magmatic bodies of the same, broadly basaltic composition. In this scenario, asteroid impacts are supposed to play no role in the formation of the Earth's early evolved crust.An alternative model suggests that these sheets may undergo large-scale chemical change to produce layered magmatic intrusions, such as the Bushveld Complex in South Africa. In this scenario, asteroid impacts may have played an important role in producing various igneous rocks in the early Earth's crust and therefore they may have contributed to its chemical evolution.There is no direct way to rigorously test these two competing scenarios because the ancient Hadean impact melts have been later obliterated by plate tectonics. However, by studying the younger impact melt sheet of the Sudbury Igneous Complex (SIC) in Canada, Latypov and his research team have inferred that ancient asteroid impacts were capable of producing various rock types from the earlier Earth's basaltic crust. Most importantly, these impacts may have made the crust compositionally more evolved, i.e. silica-rich in composition. Their research has been published in a paper in The SIC is the largest, best exposed and accessible asteroid impact melt sheet on Earth, which has resulted from a large asteroid impact 1.85 billion years ago. This impact produced a superheated melt sheet of up to 5 km thick. The SIC now shows a remarkable magmatic stratigraphy, with various layers of igneous rocks."Our field and geochemical observations -- especially the discovery of large discrete bodies of melanorites throughout the entire stratigraphy of the SIC -- allowed us to reassess current models for the formation of the SIC and firmly conclude that its conspicuous magmatic stratigraphy is the result of large-scale fractional crystallization," says Latypov."An important implication is that more ancient and primitive Hadean impact melt sheets on the early Earth and other terrestrial planets would also have undergone near-surface, large-volume differentiation to produce compositionally stratified bodies. The detachment of dense primitive layers from these bodies and their sinking into the mantle would leave behind substantial volumes of evolved rocks (buoyant crustal blocks) in the Hadean crust. This would make the crust compositionally layered and increasingly more evolved from its base towards the Earth's surface.""These impacts made the crust compositionally more evolved -- in other words, silica-rich in composition," says Latypov. "Traditionally, researchers believe that such silica-rich evolved rocks -- which are essentially building buoyant blocks of our continents -- can only be generated deep in the Earth, but we now argue that such blocks can be produced at new-surface conditions within impact melt pools."
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Geology
| 2,019 |
June 2, 2017
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https://www.sciencedaily.com/releases/2017/06/170602112819.htm
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Antarctic ice rift close to calving, after growing 17km in 6 days, latest data from ice shelf shows
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The rift in the Larsen C ice shelf in Antarctica has grown by 17km in the last few days and is now only 13km from the ice front, indicating that calving of an iceberg is probably very close, Swansea University researchers revealed after studying the latest satellite data.
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The rift in Larsen C is likely to lead to one of the largest icebergs ever recorded. It is being monitored by researchers from the UK's Project Midas, led by Swansea University.Professor Adrian Luckman of Swansea University College of Science, head of Project Midas, described the latest findings:"In the largest jump since January, the rift in the Larsen C Ice Shelf has grown an additional 17 km (11 miles) between May 25 and May 31 2017. This has moved the rift tip to within 13 km (8 miles) of breaking all the way through to the ice front, producing one of the largest ever recorded icebergs.The rift tip appears also to have turned significantly towards the ice front, indicating that the time of calving is probably very close.The rift has now fully breached the zone of soft 'suture' ice originating at the Cole Peninsula and there appears to be very little to prevent the iceberg from breaking away completely."Researchers say the loss of a piece a quarter of the size of Wales will leave the whole shelf vulnerable to future break-up.Larsen C is approximately 350m thick and floats on the seas at the edge of West Antarctica, holding back the flow of glaciers that feed into it.Professor Luckman added, "When it calves, the Larsen C Ice Shelf will lose more than 10% of its area to leave the ice front at its most retreated position ever recorded; this event will fundamentally change the landscape of the Antarctic Peninsula.We have previously shown that the new configuration will be less stable than it was prior to the rift, and that Larsen C may eventually follow the example of its neighbour Larsen B, which disintegrated in 2002 following a similar rift-induced calving event.The MIDAS Project will continue to monitor the development of the rift and assess its ongoing impact on the ice shelf. Further updates will be available on our blog (The team say they have no evidence to link the growth of this rift, and the eventual calving, to climate change. However, it is widely accepted that warming ocean and atmospheric temperatures have been a factor in earlier disintegrations of ice shelves elsewhere on the Antarctic Peninsula, most notably Larsen A (1995) and Larsen B (2002).They point out that this is one of the fastest warming places on Earth, a feature which will certainly not have hindered the development of the rift in Larsen C.
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Geology
| 2,017 |
June 2, 2017
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https://www.sciencedaily.com/releases/2017/06/170602085001.htm
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Deep magma reservoirs are key to volcanic 'super-eruptions,' new research suggests
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New study shows the importance of large reservoirs in creating Earth's most powerful volcanic eruptions and explains why they are so rare
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Large reservoirs of magma stored deep in Earth's crust are key to producing some of Earth's most powerful volcanic eruptions, new research has shown.In a new study, an international team of scientists claim that the most powerful volcanic eruptions, dubbed 'super-eruptions', are triggered by a slow and steady drip feed of magma from large reservoirs deep within Earth's crust into smaller reservoirs closer to the surface.These large reservoirs draw in hot magma from Earth's mantle and exist as large volumes of partially molten rock that are able to store magma like a sponge.By conducting a number of numerical simulations of this process, the research team showed that these large reservoirs are crucial to generating the largest volcanic eruptions on Earth.The team also showed that these large reservoirs can take millions of years to form, hence why 'super-eruptions' happen so rarely.It is believed that these findings could help to understanding why some volcanoes erupt frequently and at certain magnitudes.The study has been published in the journal The amount of magma that is stored in the upper layer of Earth's crust determines the frequency and magnitude of volcanic eruptions. Small eruptions that erupt less than one cubic kilometre of material occur very frequently (daily to yearly), whilst the largest eruptions that erupt hundreds of cubic kilometres of material are infrequent, with hundreds of thousands of years between them.Co-author of the study Dr Wim Degruyter, from Cardiff University's School of Earth and Ocean Sciences, said: "Our current understanding tells us that hot magma can be injected from Earth's lower crust into colder surroundings near the surface. At this point, the magma can either erupt or cool down to such a point that the magma solidifies and an eruption does not occur.""Up until now, this theory hasn't been able to explain how the magma can maintain its heat in these near-surface reservoirs and thus produce extremely powerful eruptions.""Our study has shown that the key to this is much larger reservoirs deeper below the surface that are able to slowly increase the temperature in the upper part of the crust such that it becomes more amenable to the storage of magma. When the crust has become fully mature, giant reservoirs are able to form in the upper crust and thus we see extremely powerful eruptions."Previous research has revealed that a deeper magma body connects to a magma reservoir in the upper part of the crust underneath Yellowstone -- one of the world's largest supervolcanoes. The deeper magma body sits 12 to 28 miles below the surface and it's believed that the hot molten rock could fill the 1,000-cubic-mile Grand Canyon 11.2 times. The last known eruptions from Yellowstone were 2m, 1.2m and 640,000 years ago, and it is believed that these were fed by the volcanic plumbing system that sits beneath it."Our calculations appear to agree with the observations that have been made at Yellowstone," Dr Degruyter continued.The study, Lifetime and size of shallow magma bodies controlled by crustal-scale magmatism, was led by researchers at ETH Zurich, and also included researchers from the Georgia Institute of Technology.
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Geology
| 2,017 |
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