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December 17, 2020 | https://www.sciencedaily.com/releases/2020/12/201217135407.htm | Can water saving traits help wine survive climate change? | Climate change is expected to make many grape-growing regions too hot and dry to produce high-quality wine from traditional varieties. But scientists at the University of California, Davis, have found that wine grape varieties from regions that are more prone to stress have traits that could help them cope with climate change. | The study, published in the Journal of Experimental Botany, finds that varieties that produce their best wines in warmer, drier regions have traits that conserve water, helping the vines extend their water resources to last over the growing season."The relationships between grape varieties and regions have historically been based on wine, without considering traits that affect drought or heat tolerance," said lead author Megan Bartlett, an assistant professor in the Department of Viticulture and Enology. "These findings show these varieties could be more resilient to climate change than expected."The study examined how grapevines regulate their stomata -- tiny pores found on the surface of leaves that allow plants to take in carbon dioxide for photosynthesis and expel oxygen. The regulation of these stomata affects how much CO2 is available for photosynthesis and how much water evaporates from the leaves. Grapevines must choose between opening their stomata to take in CO2 to produce sugars for growth and ripening or closing the stomata to reduce evaporation and water stress.A little water stress improves wine by concentrating the flavors and aromas in the grapes. But too much will prevent grapes from achieving their ideal balance of sugars, acids and tannins, creating flat, uninteresting wines.The researchers examined traits for 34 varieties and used a global database of planting areas in different wine regions to define the associations between varieties and regions. The study focused on European regions, where irrigation is banned or restricted, to directly capture the stress imposed by the local climate.The study found that the varieties grown in regions more likely to experience water stress, such as Italy's Sangiovese and Montepulciano, kept their stomata more closed than varieties like Sauvignon Blanc from cooler, more humid regions."This strategy would help these varieties save water," said study co-author Gabriela Sinclair, a research technician in the Bartlett lab.Bartlett cautions that these traits may have unintended consequences as heatwaves become more extreme. Grapevines use evaporation to cool the leaves, the same way we cool ourselves by sweating. Restricting evaporation too tightly could allow leaves to reach damaging temperatures, reducing their future photosynthesis and limiting the sugars available for ripening."We have more work to do to understand how these traits will affect grapevines as the climate reaches new extremes," said Bartlett. "These findings show that traits will be important to consider when we predict what will happen to different wine regions."Support for the research comes from the UC Davis College of Agricultural Environmental Sciences and Department of Viticulture and Enology, and by donations to the department from the Rossi family. | Climate | 2,020 |
December 17, 2020 | https://www.sciencedaily.com/releases/2020/12/201217135327.htm | Skinnier but resilient geese thriving in the high Arctic | The world is changing in dramatic ways, especially in the High Arctic. Climate change has meant that spring arrives earlier, but winters have become far more treacherous for Arctic animals that overwinter there, with more rain and ice. | So what about birds that don't overwinter in the Arctic, but nest and raise young there? Researchers have spent nearly three decades collecting data on a group of barnacle geese that migrate to the Norwegian archipelago of Svalbard to see how the geese respond to environmental changes overall.In one study they found that earlier springs linked with climate change meant better conditions for the geese, but that these benefits were cancelled out by an increase in numbers of hungry foxes -- a precarious balance that could change depending on future conditions.Now, researchers have looked at the actual physical condition of the geese as their numbers have skyrocketed at their overwintering grounds in the UK. There are more than 40,000 birds now compared to just 300 individuals in the 1940s, when the birds were still hunted in both UK and elsewhere.More birds, however, means more competition for food in their summer nesting areas on Svalbard.There's so much competition, in fact, that the average body weight of the birds has dropped by 10 per cent in the last three decades. In wild animals, reduced body weight often means reduced condition and a low ability to reproduce or survive. The question the researchers have tried to answer in a new publication is, does this really matter?The answer, it seems, is no. Not yet.Kate Layton-Matthews completed her PhD dissertation at the Norwegian University of Science and Technology's (NTNU) Centre for Biodiversity Dynamics on the geese earlier this year.She worked with a team of researchers from NTNU, the University of Groningen in the Netherlands, the University of Sheffield in the UK and the Norwegian Polar Institute in Tromsø on modelling a long-term population study on the barnacle goose.Barnacle geese breeding on Svalbard make a 3000 km long trip every spring to their Arctic breeding grounds from their overwintering areas in Scotland. That in itself requires a great deal of energy, but the birds also still need to be in good enough condition when they arrive in the Arctic to lay eggs and raise their young.As the team of researchers looked at their decades of data, they detected the 10 per cent drop in the birds' body weight.So Layton-Matthews used a complex statistical model that could digest information on body condition, reproduction and survival of the geese since 1990. The model allowed her to see if the net effect of lower body weights was actually affecting the ability of the birds to survive and reproduce, and ultimately if this has caused changes in goose population numbers."We have this kind of underlying expectation that body condition is so important for herbivores, and especially in the Arctic that your body condition can limit reproduction and probability of survival. So body weight, or body condition, could limit if they manage to have offspring or not, and also whether, especially young geese, survive their first migration," she said.Surprisingly, however, although changes in body condition do influence reproduction and survival of young geese somewhat, this did not translate into noticeable effects on population numbers."We were expecting that something so important at the individual level would have big impact on the population, but it doesn't," she said.The researchers say this is because it's overridden by other important environmental effects that don't affect the geese through body condition, such as the positive impact of earlier springs on gosling production, and the negative effect of Arctic foxes on goslings' survival.However, because there is obviously a limit to how skinny the geese can be and still perform well if their summer habitat continues to degrade, it's likely to restrict population growth at some point.The good news, Layton-Matthews said, is that this still shows the geese populations are more resilient to changes in habitat quality and body condition than researchers previously thought.The increase in goose numbers in their wintering areas has led to some places, such as Ireland, to allow the birds to be hunted again. It's also been debated whether barnacle geese hunting should be allowed on Svalbard.But Layton-Matthews says history has shown that there's a potential risk if the overwintering birds are hunted too heavily."If we start hunting a population that is really sensitive to hunting and quite sensitive to climate change, as we know this population is, we need to be very careful about the hunting levels being set," she said. "If they're going to introduce hunting at wintering or breeding grounds, we need to monitor and account for the other processes going on, notably climate change, so that they can set sensible quotas that won't harm the overall population."Maarten J.J.E. Loonen started studying barnacle geese on Svalbard three decades ago to determine how the breeding period would limit population size after the growth in population numbers due to changes on the wintering grounds. Winter populations did well because hunting was banned in Scotland in 1950, and the grasslands where they grazed were fertilized."In 1990 we thought that the Arctic would not change and Svalbard, being an island, would result in an increase of competition among the geese and a decrease breeding success," Loonen said. "In poor years, we knew that gosling growth slowed down and as a consequence these geese became smaller adults. But after thirty years of data collection, this paper shows that there is no effect of declines on population size yet." | Climate | 2,020 |
December 17, 2020 | https://www.sciencedaily.com/releases/2020/12/201217135325.htm | Change in global precipitation patterns as a result of climate change | The Earth's climate system is largely determined by the differences in temperature between the tropics and the poles. Global warming is likely to cause global atmospheric circulation to change and progressively revert to a situation similar to that of 5,000 to 10,000 years ago. This is the conclusion of a study undertaken by a research team led by Dr. Michael Deininger, the results of which have been published in | At the Institute of Geosciences at Johannes Gutenberg University Mainz (JGU), Deininger investigated how regional climate systems have changed since the beginning of the current interglacial period some 10,000 years ago and what conclusions can be drawn from this. To do this, the paleoclimatologist looked at data for rainfall time series recorded in various climate archives. "We were able to accurately reconstruct summer precipitation in the monsoon regions in Africa and South America, compare this data with changes in precipitation in the northern mid-latitudes, and relate this to changes in temperature," Deininger explained. The study also involved scientists from Australia, Brazil, Mexico, Ireland, Austria, and South Africa.As the Earth is heated stronger at the equator than at the poles due to the differing distribution of solar radiation, a temperature gradient develops which, to put it in simple terms, causes atmospheric circulation to transport energy toward the poles. Changes to this solar radiation-related temperature difference will in turn influence the atmospheric circulation and thus also regional precipitation patterns.The new study shows that over the past 10,000 years, changes to regional precipitation in the northern latitudes, Africa, and South America have more or less been synchronous. "We argue that these regional climate variations are connected and that they are mainly caused by alterations to solar radiation and the associated temperature differences between the tropics and polar regions," stated Deininger.The researchers involved in the study were particularly interested in the question of whether it is possible to learn from the past to benefit the future. With the current level of global warming, the temperature gradient between the equator and the poles is being reduced -- especially due to the fact that warming in the Arctic has a particularly marked effect. This can weaken the westerly winds in mid-latitudes in the Northern Hemisphere, cause a weaker South American monsoon and a stronger African monsoon, while at the same time lead to lower precipitation levels in the summer rainfall zone of Southeast Africa. The consequences of this could be shifts in regional rainfall patterns, potentially causing droughts in some areas and flooding in others. "In future, we need to recognize the fundamental role the variation in temperature difference plays in controlling our climate system," concluded Dr. Michael Deininger. | Climate | 2,020 |
December 17, 2020 | https://www.sciencedaily.com/releases/2020/12/201217135315.htm | Weddell sea: Whale song reveals behavioral patterns | Until recently, what we knew about the lives of baleen whales in the Southern Ocean was chiefly based on research conducted during the Antarctic summer. The reason: in the winter, there were virtually no biologists on site to watch for the animals. Experts from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now used permanently installed underwater microphones, which have been recording for the past nine years, to successfully gather and analyse whale observation data from the Weddell Sea. The audio recordings offer unique insights into the lives of humpback whales and Antarctic minke whales. They show e.g. that there are most likely two humpback whale populations in the Weddell Sea, both of which avoid the sea ice and call or sing most frequently in the autumn. In contrast, Antarctic minke whales primarily live in ice-covered regions and produce their characteristic quacking sounds in the winter, as the researchers report in two studies recently published in the online journal | Antarctic minke whales (Balaenoptera bonaerensis) are still a mystery to marine biologists, who don't know how many of these whales there are, or where exactly they live, mate and give birth to their calves. A few years ago, however, it was discovered that Antarctic minke whales produce certain characteristic sounds. These calls, which often sound a bit like the quacking of a duck, provide incontrovertible proof of the presence of the small whales, which measure up to eleven metres in length.AWI biologist Diego Filun and his team are now using these sounds in the first-ever comprehensive, long-term observation of Antarctic minke whales in the Weddell Sea. "We've been monitoring our underwater microphones for nine years. They were deployed at 21 points throughout the Weddell Sea and along the prime meridian, allowing us to record the whales' acoustic activities in regions where research vessels rarely venture. Thanks to the recordings, we now finally understand in what parts of the Weddell Sea the minke whales prefer to be at different times of year, and know that at least some of them stay there for the winter and don't migrate to warmer waters," Filun explains.The recordings from 2008 to 2016 show that, in summer and winter alike, Antarctic minke whales tend to stay in those regions of the Weddell Sea that are covered with sea ice. Yet the frequency of their calls appears to change with the season: they can be heard far more often in the autumn and winter months (April to October) than in the summer months (December to March). In addition, the acoustic observations call into question certain previous assumptions: "On aerial survey flights over the Weddell Sea in the summer, minke whales were primarily sighted near the sea-ice edge and less frequently in areas with thick sea ice. But our audio recordings showed just the opposite: the minke whales were rarely found in the marginal ice zone, and much more often under thick ice -- most likely in an attempt to avoid their archenemies, killer whales," Filun reports.In contrast, the humpback whales (Megaptera novaeangliae) of the Weddell Sea don't seek shelter below the ice. On the contrary! As the second hydroacoustic study, led by AWI biologist Elena Schall, determined, the baleen whales avoid ice-covered regions. Instead, they venture to the north of the ice edge on the hunt for Antarctic krill, which can be found in especially large swarms in the Weddell Sea and waters north of it."Our audio recordings from 2013 indicate that at least two humpback whale populations come to the Weddell Sea in summer to build up their fat reserves. Whales from South Africa seem to go hunting at the eastern edge, near the prime meridian. But humpbacks from South America tend to stay in the northern coastal waters of the Antarctic Peninsula, and can be heard until later in the year than their counterparts to the east," explains first author Elena Schall.In both groups, some of the animals don't begin the long trek to the north at summer's end, and instead overwinter in the ice-free regions of the Weddell Sea. At the same time, the recordings indicate that, in the summer, the humpbacks move southward as the ice retreats, but only go as far as is absolutely necessary to find sufficient food."If we want to protect the unique biotic communities of the Weddell Sea in the long term, we need to know as precisely as possible how many baleen whales come to the Atlantic sector of the Southern Ocean in search of food, what regions they hunt in, whether they overwinter there, and how much krill is needed for the whales to find sufficient food. In this regard, long-term acoustic observations are a vital tool, because they offer us a far more detailed picture of life below the water than the handful of scientific whale sightings alone," says Dr Ilse van Opzeeland, an AWI biologist and co-author of both studies.The team now hopes that the findings from the new studies will be taken into account in future discussions on the establishment of a marine protected area in the Weddell Sea, especially in terms of limiting krill fishing to ensure that there is still enough food for all marine fauna.In the meantime, the experts will continue to analyse their wealth of underwater recordings. First of all, they'll seek to determine the purpose of Antarctic minke whales' unusual 'quacking'; in addition, there are initial indications that the humpback whales' recorded songs and calls could be used to discover why they leave the Weddell Sea much earlier or later than normal in certain summers, or the conditions under which they sometimes don't return to the Weddell Sea at all when winter ends. Understanding these behavioural patterns would mean a major step forward for the AWI's marine biologists. | Climate | 2,020 |
December 17, 2020 | https://www.sciencedaily.com/releases/2020/12/201217112850.htm | Greenland 'knickpoints' could stall spread of glacial thinning | The jagged terrain of Greenland's mountains is protecting some of the island's outlet glaciers from warm coastal waters, according to a team of researchers that included scientists from The University of Texas at Austin and NASA. | Outlet glaciers protrude from the ice sheet into the sea, where surging ocean heat can speed up the loss of ice, making the glaciers thinner and raising sea levels. The scientists found that steep slopes in the bedrock under the ice form stabilizing areas the researchers termed "knickpoints" that prevent coastal thinning from reaching further inland.The findings were published Dec. 11 in the journal "Thinning in glaciers originates at the edge of the ice, and makes its way inland," said lead author Denis Felikson, a NASA research scientist. "When the thinning reaches a knickpoint that is steep enough, it's halted."However, in regions where the flat bedrock offers no such protection and knickpoints are absent, runaway thinning can reach far into the ice sheet and eat away at previously unaffected ice and contribute to sea level rise.Coauthor Ginny Catania, a professor of glaciology at the UT Jackson School of Geosciences, said that most glaciers are thinning as scientists expect in a warming climate, but not at the same rates or amounts. The variability makes it more difficult to predict how quickly sea levels will rise as the planet gets hotter."Some glaciers are thinning right next to others that are thickening," she said. "Until now we didn't know how to explain such variability. Denis' research has provided a framework for that understanding, and it's very likely that all of the variability we observe in outlet glaciers is linked to variability in the bed topography between glaciers."The researchers use the term knickpoints to describe steep slopes in the bedrock because of their similarities to river knickpoints -- places that often form waterfalls or rapids. Like a waterfall, glaciers pour over the knickpoints, creating a physical barrier that prevents changes happening downstream near the coast from reaching further upstream.Greenland's ice sheet covers an area twice the size of Texas. The barrier effect of knickpoints is important because warmer ocean currents are one of the principal reasons Greenland's glaciers are losing mass more quickly than they were 20 years ago.The study gives scientists a better understanding of how the loss of ice will play out as the world gets hotter and can also focus scientific resources on learning more about the glaciers most likely to contribute to sea level rise.Felikson began the research while earning a Ph.D. at the Jackson School working with Catania and coauthor Tim Bartholomaus (now at the University of Idaho) at the University of Texas Institute for Geophysics (UTIG). By comparing the start-stop motion of glacial creep to congested traffic, the UTIG group had shown that a glacier's shape controls the spread of thinning in a 2017 The current paper builds on that research but extends the analysis from 16 to 141 (the majority) of Greenland's outlet glaciers, and in doing so, revealed the armoring effect of glacial knickpoints.The research shows that glacial knickpoints are surprisingly prevalent. Although that might be good news, the research also revealed vulnerability in northwest Greenland, an overlooked region of the ice sheet."The glaciers in this region could be important over the next 100 years because the relatively flat bedrock beneath them means they can transfer thinning much further into the interior of the ice sheet than some of the larger glaciers in mountainous topography," Felikson said.Catania said this means that sea levels will rise regardless."You're still going to drain the ice sheet you're just going to do so through a different area than we thought," she said.The research team agreed that investigations of the bedrock near the coast is urgently required to learn how effective knickpoints are at holding back coastal warming, as is investigation of unprotected glaciers. Catania and Felikson have already proposed an early warning system that will use machine learning to watch for instability in glaciers identified by the knickpoint analysis.Felikson is a research scientist at Universities Space Research Association and the NASA Goddard Space Flight Center. UTIG is a unit of the Jackson School. The research was funded by a NASA grant and the Gale White Fellowship at UTIG. | Climate | 2,020 |
December 17, 2020 | https://www.sciencedaily.com/releases/2020/12/201217092354.htm | Colorado river mystery solved: Ancient shallow sea with strong tides | A team led by University of Oregon geologist Rebecca Dorsey has published two papers that provide new insights into the origins of the Colorado River, using data from ancient sedimentary deposits located east of the San Andreas fault near the Salton Sea in Southern California. | The papers, led by former master's student Brennan O'Connell and doctoral candidate Kevin Gardner, respectively, present evidence that the now desert landscape of the river's lower valley was submerged roughly 5 million to 6 million years ago under shallow seas with strong, fluctuating tidal currents that flowed back and forth along the trajectory of the present-day river.Layers of sedimentary rocks bearing marine fossils, burrows and diagnostic sedimentary structures, the researchers concluded, record a dramatic rise in sea level that drowned former alluvial fans and caused tidal waters to invade the valley prior to arrival of the Colorado River and its voluminous load of water and sediment.The studies, both funded by the National Science Foundation, were published online ahead of print in the international journal The first paper, which published Oct. 29 and was led by O'Connell, who is now pursuing a doctorate at the University of Melbourne in Australia, focused on sediments of the late Miocene to early Pliocene Bouse Formation exposed east of the Colorado River, south of Blythe, California.Previously, O'Connell and a team of UO geologists had found evidence that the Gulf of California once reached as far north as Blythe, as detailed in the journal Geology in 2017.In the new paper, O'Connell and co-authors describe a rich mixture of carbonate mudstones, plant debris and traces of ancient organisms that record brackish water conditions where seawater was diluted by a large influx of fresh water due to high annual rainfall, before waters of the Colorado River flowed into the area.The sediments, they found, formed in wide tidal flats along an ancient, humid-climate marine shoreline. An abrupt transition to low-energy subtidal lime mudstone records widespread marine flooding associated with a long-lived regional rise in sea level, they concluded. Relative sea level rise, they added, resulted from long-term tectonically controlled subsidence.The combined evidence from paleontology, ichnology and process sedimentology "provides a clear record of freshwater input and brackish water conditions due to mixing of freshwater and seawater in a humid climate with high annual precipitation," O'Connell's team wrote.The second paper, published Dec. 5 and led by Gardner, documents tidal sediments of the same age on the opposite side of the same ancient tidal strait. The sediments accumulated where strong daily reversing currents swept north and south along the axis of the tidal strait, driving migration of large subtidal dunes and depositing large scale cross-bedded carbonate sands.The authors argue that the migrating dune bedforms could not have formed by tidal like processes in a lake, as some scientists have proposed. The team's results indicate that, after late Miocene to early Pliocene deposition, the sediments were uplifted to elevations up to 330 meters above sea level in the Chocolate Mountains, as a result of long-term crustal strain related to motion on the San Andreas fault."Taken together, our new papers provide conclusive evidence that the southern Bouse Formation formed in and around the margins of a marine tidal strait that filled the lower Colorado River valley prior to arrival of the modern river system," said Dorsey, a professor in the UO's Department of Earth Sciences.A map of the southern Bouse tidal seaway, reconstructed with data from both studies, shows that desert communities from Blythe to Palo Verde, California, were submerged under shallow seas with strong fluctuating tidal currents during late Miocene to early Pliocene time.The Miocene, a geological epoch, lasted from 23 million years ago to 5.3 million years ago; the Pliocene occurred between 5.3 million and 2.6 million years ago.Co-authors with O'Connell and Dorsey on the first paper were Stephen T. Hasiotis, a geologist at the University of Kansas, and Ashleigh Hood at the University of Melbourne.In 2018, another Dorsey-led paper in the journal | Climate | 2,020 |
December 16, 2020 | https://www.sciencedaily.com/releases/2020/12/201216155159.htm | Carbon capture's next top model | In the transition toward clean, renewable energy, there will still be a need for conventional power sources, like coal and natural gas, to ensure steady power to the grid. Researchers across the world are using unique materials and methods that will make those conventional power sources cleaner through carbon capture technology. | Creating accurate, detailed models is key to scaling up this important work. A recent paper led by the University of Pittsburgh Swanson School of Engineering examines and compares the various modeling approaches for hollow fiber membrane contactors (HFMCs), a type of carbon capture technology. The group analyzed over 150 cited studies of multiple modeling approaches to help researchers choose the technique best suited to their research."HFMCs are one of the leading technologies for post-combustion carbon capture, but we need modeling to better understand them," said Katherine Hornbostel, assistant professor of mechanical engineering and materials science, whose lab led the analysis. "Our analysis can guide researchers whose work is integral to meeting our climate goals and help them scale up the technology for commercial use."A hollow fiber membrane contactor (HFMC) is a group of fibers in a bundle, with exhaust flowing on one side and a liquid solvent on the other to trap the carbon dioxide. The paper reviews state-of-the-art methods for modeling carbon capture HFMCs in one, two and three dimensions, comparing them in-depth and suggesting directions for future research."The ideal modeling technique varies depending on the project, but we found that 3D models are qualitatively different in the nature of information they can reveal," said Joanna Rivero, graduate student working in the Hornbostel Lab and lead author. "Though cost limits their wide use, we identify 3D modeling and scale-up modeling as areas that will greatly accelerate the progress of this technology."Grigorios Panagakos, research engineer and teaching faculty in Carnegie Mellon University's Department of Chemical Engineering, brought his expertise in analyzing the modeling of transport phenomena to the review paper, as well. | Climate | 2,020 |
December 16, 2020 | https://www.sciencedaily.com/releases/2020/12/201216134651.htm | Monitor groundwater along river corridors | Spend time in any of the world's great forests and you'll start seeing the trees as immense pillars holding the heavens aloft while firmly anchored in the earth. It's as much fact as sentiment. Trees really do link the ground to the sky by exchanging energy and matter between the soil and the atmosphere. Researchers believe that understanding this connection could provide both a wealth of scientific insight into ecosystems and practical applications that address challenges such as water resource conservation and management. | A recent study led by UC Santa Barbara's Marc Mayes investigates how patterns in tree water loss to the atmosphere, tracked with satellite imagery, relates to groundwater supplies. The results validate at landscape-wide scales ideas that scientists have proposed based on decades of research in labs and greenhouses. What's more, the techniques lend themselves to an accurate, efficient way of monitoring groundwater resources over large areas. The findings appear in the journal For all their diversity, most plants have a very simple game plan. Using energy from sunlight, they combine water from the ground with carbon dioxide from the air to produce sugars and oxygen. During photosynthesis, plants open small pores in their leaves to take in COJust like evaporating sweat cools down our own bodies, the evapotranspiration from the trees cools down the forest. With the proper understanding and technology, scientists can use thermal image data from satellites as well as manned and unmanned aircraft to understand the relationship between plants and groundwater: cooler temperatures correlate with more evapotranspiration."The core hypothesis of this paper is that you can use relationships between plant water use [as] measured by [satellite] image data, and climate data including air temperature and rainfall, to gauge the availability of, and changes in, groundwater resources," said Mayes, an Earth scientist and remote sensing expert based at the university's Earth Research Institute (ERI).Mayes and his colleagues focused on the flora of dryland rivers -- those in deserts and Mediterranean climates. Throughout these regions, many plants have evolved adaptations that minimize water loss, like slow growth, water retention or boom-bust lifecycles. However, plants that dominate river channels -- species like sycamore, cottonwood and willows -- evolved to take advantage of the surplus groundwater the habitat offers relative to the surrounding landscape."Rather than slowing down its water use when water becomes scarce, this vegetation will basically drink itself to death," Mayes said. This makes it a good window into conditions below the surface.The team used satellite-based thermal imaging to look at temperatures across the San Pedro River corridor in southern Arizona. On cloud-free days the satellites can gather data on surface temperatures at high resolution over large areas of land. By comparing the temperatures along the river to those in nearby, more sparsely vegetated areas, the researchers were able to determine the extent of evapotranspiration along different parts of the river at different times. They found that it correlated with air temperature in water-rich environments and with rainfall in water-scarce environments.The findings support recent advances in our understanding of plant water use. The hotter and drier the air, the stronger it pulls water from the leaves, and the more water the plant uses. Consequently, Mayes and his colleagues expected to see evapotranspiration vary with air temperature as long as the stream has abundant groundwater for the plants to draw on.On the other hand, where groundwater is scarce, plants will close the openings on their leaves to avoid water loss; it's more important to avoid drying out than to take advantage of the extra sunshine on a warm day. As a result, evapotranspiration will correlate much more strongly with rainfall and streamflow, which increases the supply of water to trees through their roots.Scientists had demonstrated the predictable effect of evapotranspiration in lowering surface temperatures in lab and small field experiments. However, this is the first study to demonstrate its impact over large areas. The technology that made this possible has matured only within the past five years."This remote sensing method shows great promise for identifying the relevant climatic versus other controls on tree growth and health, even within narrow bands of vegetation along rivers," said coauthor Michael Singer, a researcher at ERI and lead investigator on the project that funded Mayes' work.In fact, these ecosystems are vitally important to the southwestern U.S. "Despite taking up about 2% of the landscape, over 90% of the biodiversity in the Southwest relies on these ecosystems," said coauthor Pamela Nagler, a research scientist at the U.S. Geological Survey's Southwest Biological Science Center.The same techniques used in the paper could be applied to the perennial challenge of groundwater monitoring. In fact, this idea helped motivate the study in the first place. "It's very hard to monitor groundwater availability and change[s] in groundwater resources at the really local scales that matter," Mayes said. "We're talking about farmers' fields or river corridors downstream of new housing developments."Monitoring wells are effective, but provide information only for one point on the map. What's more, they are expensive to drill and maintain. Flux towers can measure the exchange of gasses between the surface and the atmosphere, including water vapor. But they have similar drawbacks to wells in terms of cost and scale. Scientists and stakeholders want reliable, cost-effective methods to monitor aquifers that provide wide coverage at the same time as high resolution. It's a tall order.While it may not be quite as precise as a well, remote thermal imaging from aircraft and satellites can check off all of these boxes. It offers wide coverage and high resolution using existing infrastructure. And although it works only along stream corridors, "an inordinate amount of agricultural land and human settlements in dry places ends up being where the water is, along stream paths," Mayes said.The idea is to look for shifts in the relationships of evapotranspiration to climate variables over time. These changes will signal a switch between water-rich and water-poor conditions. "Detecting that signal over large areas could be a valuable early warning sign of depleting groundwater resources," Mayes said. The technique could inform monitoring and pragmatic decision-making on groundwater use.This study is part of a larger Department of Defense (DOD) project aimed at understanding how vulnerable riverine habitats are to droughts on DOD bases in dryland regions of the U.S. "We are using multiple methods to understand when and why these plants become stressed due to lack of water," said Singer, the project's lead scientist. "[We hope] this new knowledge can support the management of these sensitive ecological biomes, particularly on military bases in dryland regions, where these pristine habitats support numerous threatened and endangered species."Mayes added, "What's coming down the pipe is a whole ensemble of work looking at ecosystem responses to water scarcity and water stress across space and time that informs ways we both understand ecosystem response and also improve the monitoring." | Climate | 2,020 |
December 16, 2020 | https://www.sciencedaily.com/releases/2020/12/201216104629.htm | Infrastructure key to balancing climate and economic goals in developing countries | Developing nations have an opportunity to avoid long-term dependence on fossil fuel-burning infrastructure as they move toward economic stability, even if they are slow to cut carbon emissions, say the authors of a new paper in | Countries with low per capita incomes can keep their contributions to global warming to 0.3 degrees Celsius with careful foresight and planning, urge Carnegie's Lei Duan and Ken Caldeira with Juan Moreno-Cruz of the University of Waterloo. However, fueling economic development with coal, oil, or gas risks locking societies into a fossil-fuel burning infrastructure in the long-term, the authors caution."People in less wealthy countries are often motivated to use fossil fuels to drive their economic development and meet basic human needs," said lead author, Carnegie's Lei Duan. He continued, "While the direct climate effects from emissions from poor people will be minor, the world will care what kinds of energy systems they have as they increase their wealth."More than half of the world's population resides in countries that have a per capita gross domestic product of less than $10,000 per year. But these nations produce less than 7 percent of global carbon dioxide emissions.So Duan, Caldeira, and Juan Moreno-Cruz of the University of Waterloo set out to determine the consequences to the climate if only richer countries focused on decarbonization and developing countries delayed emissions cuts until they achieved economic stability.They tested several future scenarios in which carbon emissions were cut only when countries reached specified levels of economic growth.If every country in the world started to cut emissions by 2 percent annually in 2020, the world would warm to the climate-stabilizing Paris Agreement goal of 2 degrees Celsius over the pre-industrial era. However, Duan explained, "we determined that if decarbonization began only when a country reached a $10,000 per capita GDP, it would cause less than 0.3 degrees Celsius additional warming. This demonstrates that the onus of fighting climate change really falls on the shoulders of more developed nations."This is, in part, because developing nations tend to prioritize low-cost and easy to operate energy sources. In fact, the authors said that the biggest risk to allowing these countries to delay emissions cuts would be the possibility of their constructing more-permanent fossil-fuel-burning infrastructure that would be too costly to eliminate.In fact, last year, a study on which Caldeira was a coauthor determined that the world's power plants, boilers, furnaces, vehicles, and other fossil fuel technology must be retired early to meet the Paris Agreement goal."My professional career has been focused on addressing the climate problem, but I could do that because I had access to food, and shelter, and education, and energy and a thousand other things," Caldeira said. "If I didn't have those things, I would be focused on getting those things. We in the rich world can't fault anybody for trying to meet basic needs. We need to be thinking about ways to help people meet their basic needs today, while we help them and ourselves to transition to an energy system that does not use the sky as a waste dump." | Climate | 2,020 |
December 16, 2020 | https://www.sciencedaily.com/releases/2020/12/201216085032.htm | Babbler bird falls into climate change trap | Animals can fall into an "ecological trap" by altering their behaviour in the "wrong direction" in response to climate change, researchers say. | The so-called "rescue hypothesis" suggests many species might successfully adapt to changing conditions, especially those that are flexible in their behaviour.But a new study, by the University of Exeter, found that chestnut-crowned babbler birds responded to rising temperatures by changing their behaviour in ways that could actually reduce successful breeding.This occurred because they reacted to warm peak temperatures in early spring by breeding earlier -- but average temperatures at this time are still colder than later in spring, which is bad for incubating eggs.Instead of spending more time incubating, females responded to the cold by incubating less -- which might improve their own survival chances but exposes their developing eggs to harmful, low temperatures."We hope that animals that are more responsive to changes in their environment can cope better with climate change, but unfortunately they can make mistakes that make their situation even worse," said Alex Cones, who worked on this research during her masters at the University of Exeter.Professor Andy Russell, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall, said: "Many animals breed as early as they can in spring, and climate change is causing this to happen earlier and earlier."Paradoxically, our study shows that earlier breeding in response to warming means babbler eggs and offspring are more exposed to the cold."Babblers should respond by incubating their eggs more, but they don't."Incubating eggs is more costly for the mother in terms of energy in low temperatures, so they focus on their own survival and reduce incubation."Professor Russell added: "Parental care is adaptable, not fixed, but in this case the birds adapt in the wrong direction for their chicks' survival -- falling into an ecological 'trap'."Chestnut-crowned babblers live in desert habitats in south-east Australia.Their eggs must be kept at more than 25°C (77°F) to survive, and development happens best and fastest at about 38°C (100°F).The researchers say more studies are required to discover whether "plastic" (adaptable) parenting could provide an "evolutionary rescue package" to protect species from environmental change.But they conclude that the evidence from this study is "not encouraging."The study was funded by the Natural Environment Research Council (NERC). | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215142220.htm | Attitudes about climate change are shifting, even in Texas | Longstanding skepticism among Texans toward the climate movement has shifted, and attitudes in the nation's leading energy-producing state now mirror those in the rest of the United States. | About 80% of Americans -- almost 81% of Texans -- say they believe climate change is happening, according to new research by UH Energy and the University of Houston Hobby School of Public Affairs. Slightly lower percentages said they believe the change is driven by human activities.Most said they are willing to pay more for electricity derived from natural gas produced without venting and flaring, electricity derived from renewable generation that factors in the cost of the grid, and low-carbon or carbon-neutral transportation fuels and other energy products."People are aware of climate change and believe it is real," said Ramanan Krishnamoorti, chief energy officer at UH. "That is true even in Texas, where people have been less likely to say they believe in climate change and, especially, change caused by human activities."But Krishnamoorti said researchers also found that while most people understand the link between climate change and fossil fuels, they are less sophisticated in their knowledge about potential solutions, from carbon taxes to emissions trading systems. Only 58% believe individual consumer choices are responsible for climate change.The report, Carbon Management: Changing Attitudes and an Opportunity for Action, was released less than a month before the Texas Legislature convenes a session expected to address curbing methane flaring and other emissions. The Biden administration also is likely to consider more stringent environmental regulations, and a number of energy companies have committed to reducing their carbon footprints."With so much potential for change ahead, we wanted to assess public attitudes about climate change and support for specific policies aimed at curbing emissions," said Pablo Pinto, director of the Center for Public Policy at the Hobby School. "We found people are worried about climate change and want it to be addressed, but many people, especially older residents, don't understand the strategies being considered."The researchers will present a webinar discussing the results at noon Friday, Dec. 8. The full report is available on the UH Energy and Hobby School websites.While large majorities said government, the fossil fuel industry and the transportation sector bear responsibility for climate change, fewer said individual consumer choices were responsible, said Gail Buttorff, co-director of the Survey Research Institute at the Hobby School. Still, among people who were better informed on the topic, about 76% said individual choices were partly to blame."We also found that more than 93% are willing to pay more for carbon-neutral energy, and 75% said they would pay between $1 and $5 more per gallon," Buttorff said.The researchers found generational differences in support for paying higher prices in exchange for carbon-neutral energy, with younger people generally more willing to pay a higher premium.Francisco Cantú, co-director of the Survey Research Institute at the Hobby School, said demographic changes are likely one reason the study found few differences in attitudes between Texans and people elsewhere in the U.S."Texas has a growing population of young people, along with increased migration both from other states and other countries," Cantú said. "That, along with major changes that are already underway in the industry, from the growing use of renewables to industry pledges to decarbonize, suggests regulators could take advantage of the timing to lock in long-term climate strategies."In addition to Krishnamoorti, Pinto, Buttorff and Cantú, Yewande O. Olapade, a post-doctoral fellow at the Hobby School, and Aparajita Datta, a doctoral student in the Department of Political Science, were involved in the work.The survey was conducted online in October, surveying 1,000 people age 18 and older living in all 50 states and the District of Columbia. An additional 500 residents in Texas were surveyed. | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215142218.htm | AI model shows promise to generate faster, more accurate weather forecasts | Today's weather forecasts come from some of the most powerful computers on Earth. The huge machines churn through millions of calculations to solve equations to predict temperature, wind, rainfall and other weather events. A forecast's combined need for speed and accuracy taxes even the most modern computers. | The future could take a radically different approach. A collaboration between the University of Washington and Microsoft Research shows how artificial intelligence can analyze past weather patterns to predict future events, much more efficiently and potentially someday more accurately than today's technology.The newly developed global weather model bases its predictions on the past 40 years of weather data, rather than on detailed physics calculations. The simple, data-based A.I. model can simulate a year's weather around the globe much more quickly and almost as well as traditional weather models, by taking similar repeated steps from one forecast to the next, according to a paper published this summer in the Journal of Advances in Modeling Earth Systems."Machine learning is essentially doing a glorified version of pattern recognition," said lead author Jonathan Weyn, who did the research as part of his UW doctorate in atmospheric sciences. "It sees a typical pattern, recognizes how it usually evolves and decides what to do based on the examples it has seen in the past 40 years of data."Although the new model is, unsurprisingly, less accurate than today's top traditional forecasting models, the current A.I. design uses about 7,000 times less computing power to create forecasts for the same number of points on the globe. Less computational work means faster results.That speedup would allow the forecasting centers to quickly run many models with slightly different starting conditions, a technique called "ensemble forecasting" that lets weather predictions cover the range of possible expected outcomes for a weather event -- for instance, where a hurricane might strike."There's so much more efficiency in this approach; that's what's so important about it," said author Dale Durran, a UW professor of atmospheric sciences. "The promise is that it could allow us to deal with predictability issues by having a model that's fast enough to run very large ensembles."Co-author Rich Caruana at Microsoft Research had initially approached the UW group to propose a project using artificial intelligence to make weather predictions based on historical data without relying on physical laws. Weyn was taking a UW computer science course in machine learning and decided to tackle the project."After training on past weather data, the A.I. algorithm is capable of coming up with relationships between different variables that physics equations just can't do," Weyn said. "We can afford to use a lot fewer variables and therefore make a model that's much faster."To merge successful A.I. techniques with weather forecasting, the team mapped six faces of a cube onto planet Earth, then flattened out the cube's six faces, like in an architectural paper model. The authors treated the polar faces differently because of their unique role in the weather as one way to improve the forecast's accuracy.The authors then tested their model by predicting the global height of the 500 hectopascal pressure, a standard variable in weather forecasting, every 12 hours for a full year. A recent paper, which included Weyn as a co-author, introduced WeatherBench as a benchmark test for data-driven weather forecasts. On that forecasting test, developed for three-day forecasts, this new model is one of the top performers.The data-driven model would need more detail before it could begin to compete with existing operational forecasts, the authors say, but the idea shows promise as an alternative approach to generating weather forecasts, especially with a growing amount of previous forecasts and weather observations. | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215142216.htm | Error correction means California's future wetter winters may never come | California and other areas of the U.S. Southwest may see less future winter precipitation than previously projected by climate models. After probing a persistent error in widely used models, researchers at the Department of Energy's Pacific Northwest National Laboratory estimate that California will likely experience drier winters in the future than projected by some climate models, meaning residents may see less spring runoff, higher spring temperatures, and an increased risk of wildfire in coming years. | Earth scientist Lu Dong, who led the study alongside atmospheric scientist Ruby Leung, presented her findings at the American Geophysical Union's fall meeting on Tuesday, Dec. 1, and will answer questions virtually on Wednesday, Dec. 16.As imperfect simulations of vastly complex systems, today's climate models have biases and errors. When new model generations are refined and grow increasingly accurate, some biases are reduced while others linger. One such long-lived bias in many models is the misrepresentation of an important circulation feature called the intertropical convergence zone, commonly known as the ITCZ.The ITCZ marks an area just north of the Earth's equator where northeast trade winds from the northern hemisphere clash with southeast trade winds from the southern hemisphere. Strong sunlight and warm water heat the air here, energizing it along with the moisture it holds to move upward.As the air rises, it expands and cools. Condensing moisture provides more energy to produce thunderstorms with intense rainfall. From space, one can even see a thick band of clouds, unbroken for hundreds of miles as they move about the region."The ITCZ produces the strongest, long line of persistent convection in the world," said Dong. "It can influence the global water cycle and climate over much of the Earth," including, she added, California's climate.Many climate models mistakenly depict a double ITCZ: two bands appearing in both hemispheres instead of one, which imbues uncertainty in model projections. Scientists refer to this as the double-ITCZ bias. Variations in the wind and pressure systems that influence the ITCZ add to that uncertainty."There's a lot of uncertainty in California's future precipitation," said Dong, who described climate models that project a range of winter wetness in the state averaged over multiple years, from high increases to small decreases. "We want to know where this uncertainty comes from so we can better project future changes in precipitation."To peer through the effect of the double-ITCZ bias and create more accurate projections, Dong and atmospheric scientist Ruby Leung analyzed data from nearly 40 climate models, uncovering statistical and mechanistic links between the bias and the models' outputs. The lion's share of the models they analyzed projected a sharpening of California's seasonal precipitation cycle, bringing wetter winters and drier fall and spring seasons.Soft, white snow rests on either side of a California waterway. Winter precipitation includes more than just rain, encompassing snowpack in mountainous areas and other factors that influence climate processes throughout the year.Those uncovered relationships, Dong said, now cast doubt on estimations from CMIP5 models that projected wetter winters in the future. Models saddled with a larger double-ITCZ bias, it turns out, tend to exaggerate the U.S. Southwest's wetter winters. They also understate the drier winters in the Mediterranean Basin, which also features pronounced wet winters and dry summers similar to California, under warming climate scenarios.Correcting for the bias reduces winter precipitation projections to a level that's roughly equal to California's current winters, amounting to little change and no future wetter winters. In the Mediterranean Basin, said Dong, the correction means winter drying will be intensified by 32 percent."An important implication of this work," said Dong, "is that a reduction in estimated winter precipitation will likely mean a reduction in spring runoff and an increase in spring temperature, and both increase the likelihood of wildfire risk in California."Though the study's focus was restricted solely to winter precipitation, said Leung, its implications reach to all seasons."The implications aren't just about how wet things will or won't be," said Leung. "When people think about precipitation, they tend to think about how much rain they'll get. But precipitation has a lot of implications, like snowpack in mountainous areas, for example, and that means whatever changes we see in winter precipitation will have subsequent implications for springtime or even summertime. The impacts don't just affect winter; they'll be felt throughout the year."The findings do not bode well for agricultural production, as over one third of the country's vegetables are grown in California soil, and two thirds of its fruits and nuts are grown on California farms, according to the California Department of Food and Agriculture. Almonds and grapes, two especially water-hungry crops, were among the state's top producing commodities, bringing in a combined $11.5 billion in 2019.Over 4 million acres and nearly 10,500 structures burned in the state's 2020 wildfire season. The fire season has grown longer, according to Cal Fire, which cites warmer spring temperatures as one of the reasons forests are now more susceptible to wildfire.Dong and her research partners hope the findings will better inform resource management groups as they prepare for coming wildfire seasons and plan for drier-than-expected winters.The double-ITCZ bias is prominent in all CMIP5 climate models, said Leung, as well as CMIP6 models, the most recent generation, though the latter were not considered in this work. "If you look at the whole ensemble of models," said Leung, "you see quite similar biases."This research was funded by the Department of Energy Office of Science Biological and Environmental Research as part of the Regional and Global Modeling and Analysis program area. | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215140833.htm | Oceanographers have an explanation for the Arctic's puzzling ocean turbulence | Eddies are often seen as the weather of the ocean. Like large-scale circulations in the atmosphere, eddies swirl through the ocean as slow-moving sea cyclones, sweeping up nutrients and heat, and transporting them around the world. | In most oceans, eddies are observed at every depth and are stronger at the surface. But since the 1970s, researchers have observed a peculiar pattern in the Arctic: In the summer, Arctic eddies resemble their counterparts in other oceans, popping up throughout the water column. However, with the return of winter ice, Arctic waters go quiet, and eddies are nowhere to be found in the first 50 meters beneath the ice. Meanwhile, deeper layers continue to stir up eddies, unaffected by the abrupt change in shallower waters.This seasonal turn in Arctic eddy activity has puzzled scientists for decades. Now an MIT team has an explanation. In a paper published today in the By modeling the physics of the ocean, they found that wintertime ice acts as a frictional brake, slowing surface waters and preventing them from speeding into turbulent eddies. This effect only goes so deep; between 50 and 300 meters deep, the researchers found, the ocean's salty, denser layers act to insulate water from frictional effects, allowing eddies to swirl year-round.The results highlight a new connection between eddy activity, Arctic ice, and ocean stratification, that can now be factored into climate models to produce more accurate predictions of Arctic evolution with climate change."As the Arctic warms up, this dissipation mechanism for eddies, i.e. the presence of ice, will go away, because the ice won't be there in summer and will be more mobile in the winter," says John Marshall, professor of oceanography at MIT. "So what we expect to see moving into the future is an Arctic that is much more vigorously unstable, and that has implications for the large-scale dynamics of the Arctic system."Marshall's co-authors on the paper include lead author Gianluca Meneghello, a research scientist in MIT's Department of Earth, Atmospheric and Planetary Sciences, along with Camille Lique, Pal Erik Isachsen, Edward Doddridge, Jean-Michel Campin, Healther Regan, and Claude Talandier.For their study, the researchers assembled data on Arctic ocean activity that were made available by the Woods Hole Oceanographic Institution. The data were collected between 2003 and 2018, from sensors measuring the velocity of the water at different depths throughout the water column.The team averaged the data to produce a time series to produce a typical year of the Arctic Ocean's velocities with depth. From these observations, a clear seasonal trend emerged: During the summer months with very little ice cover, they saw high velocities and more eddy activity at all depths of the ocean. In the winter, as ice grew and increased in thickness, shallow waters ground to a halt, and eddies disappeared, whereas deeper waters continued to show high-velocity activity."In most of the ocean, these eddies extend all the way to the surface," Marshall says. "But in the Arctic winter, we find that eddies are kind of living beneath the surface, like submarines hanging out at depth, and they don't get all the way up to the surface."To see what might be causing this curious seasonal change in eddy activity, the researchers carried out a "baroclinic instability analysis." This model uses a set of equations describing the physics of the ocean, and determines how instabilities, such as weather systems in the atmosphere and eddies in the ocean, evolve under given conditions.The researchers plugged various conditions into the model, and for each condition they introduced small perturbations similar to ripples from surface winds or a passing boat, at various ocean depths. They then ran the model forward to see whether the perturbations would evolve into larger, faster eddies.The researchers found that when they plugged in both the frictional effect of sea ice and the effect of stratification, as in the varying density layers of the Arctic waters, the model produced water velocities that matched what the researchers initially saw in actual observations. That is, they saw that without friction from ice, eddies formed freely at all ocean depths. With increasing friction and ice thickness, waters slowed and eddies disappeared in the ocean's first 50 meters. Below this boundary, where the water's density, i.e. its stratification, changes dramatically, eddies continued to swirl.When they plugged in other initial conditions, such as a stratification that was less representative of the real Arctic ocean, the model's results were a weaker match with observations."We're the first to put forward a simple explanation for what we're seeing, which is that subsurface eddies remain vigorous all year round, and surface eddies, as soon as ice is around, get rubbed out because of frictional effects," Marshall explains.Now that they have confirmed that ice friction and stratification have an effect on Arctic eddies, the researchers speculate that this relationship will have a large impact on shaping the Arctic in the next few decades. There have been other studies showing that summertime Arctic ice, already receding faster year by year, will completely disappear by the year 2050. With less ice, waters will be free to swirl up into eddies, at the surface and at depth. Increased eddy activity in the summer could bring in heat from other parts of the world, further warming the Arctic.At the same time, the wintertime Arctic will be ice covered for the foreseeable future, notes Meneghello. Whether a warming Arctic will result in more ocean turbulence throughout the year or in a stronger variability over the seasons will depend on sea ice's strength.Regardless, "if we move into a world where there is no ice at all in the summer and weaker ice during winter, the eddy activity will increase," Meneghello says. "That has important implications for things moving around in the water, like tracers and nutrients and heat, and feedback on the ice itself." | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215112018.htm | The melting of the Greenland ice sheet could lead to a sea level rise of 18 cm in 2100 | A new study, headed by researchers from the Universities of Liège and Oslo, applies the latest climate models, of which the MAR predicts a 60% greater melting of the Greenland ice sheet than previously predicted. Data that will be included in the next IPCC report. This study is published in | The Greenland ice sheet, the second largest after the Antarctic's, covers an area of 1.7 million square kilometres. Its total melting could lead to a significant rise in ocean levels, up to 7 metres. Although we are not there yet, the previous scenarios predicted by climate models have just been revised upwards, predicting a rise in sea levels of up to 18 cm by 2100 (compared to the 10 cm announced previously) just because of the increase in surface melting. Within the framework of the next IPCC report (AR6) which will appear in 2022, the University of Liège Laboratory of climatology has been led to apply, within the framework of the ISMIP6 project, the MAR climate model which it is developing to downscale the old and new IPCC scenarios. The results obtained showed that for the same evolution of greenhouse gas concentrations till 2100, these new scenarios predict a 60% greater surface melting of the Greenland ice cap than previously estimated for the previous IPCC report (AR5, 2013).The MAR model was the first to demonstrate that the Greenland ice sheet would melt further with a warming of the Arctic in summer. While our MAR model suggested that in 2100 the surface melting of the Greenland ice sheet would contribute to a rise in the oceans of around ten centimetres in the worst-case scenario (i.e. if we do not change our habits)," explains Stefan Hofer, post-doc researcher at the University of Oslo, "our new projections now suggest a rise of 18 cm." As the new IPCC scenarios are based on models whose physics have been improved -- in particular by incorporating a better representation of cloudiness -- and whose spatial resolution has been increased, these new projections should in theory be more robust and reliable.The team of the Laboratory of Climatology was the first to downscale these scenarios on the Greenland ice cap. "It would now be interesting, says Xavier Fettweis, researcher and director of the Laboratory, to analyse how these future projections are sensitive to the MAR model that we are developing by downscalling these scenarios with other models than MAR as we have done on the present climate (GrSMBMIP)." This study will be carried out within the framework of the European project PROTECT (H2020). The objective of this project is to assess and project changes in the terrestrial cryosphere, with fully quantified uncertainties, in order to produce robust global, regional and local projections of sea level rise over a range of time scales.The data collected as part of the Katabata project, launched last September by Xavier Fettweis and his colleague Damien Ernst, will also help to refine the models, particularly the wind model-ling in the MAR climate model. "Knowing that the wind influences the melting of the ice sheet, it is important to have the most reliable models possible, concludes Xavier Fettweis." | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215112017.htm | Climate change -- not Genghis Khan -- caused the demise of Central Asia's river civilizations, research shows | A new study challenges the long-held view that the destruction of Central Asia's medieval river civilizations was a direct result of the Mongol invasion in the early 13th century CE. | The Aral Sea basin in Central Asia and the major rivers flowing through the region were once home to advanced river civilizations which used floodwater irrigation to farm.The region's decline is often attributed to the devastating Mongol invasion of the early 13th century, but new research of long-term river dynamics and ancient irrigation networks shows the changing climate and dryer conditions may have been the real cause.Research led by the University of Lincoln, UK, reconstructed the effects of climate change on floodwater farming in the region and found that decreasing river flow was equally, if not more, important for the abandonment of these previously flourishing city states.Mark Macklin, author and Distinguished Professor of River Systems and Global Change, and Director of the Lincoln Centre for Water and Planetary Health at the University of Lincoln said: "Our research shows that it was climate change, not Genghis Khan, that was the ultimate cause for the demise of Central Asia's forgotten river civilizations."We found that Central Asia recovered quickly following Arab invasions in the 7th and 8th centuries CE because of favourable wet conditions. But prolonged drought during and following the later Mongol destruction reduced the resilience of local population and prevented the re-establishment of large-scale irrigation-based agriculture."The research focused on the archaeological sites and irrigation canals of the Otrar oasis, a UNESCO World Heritage site that was once a Silk Road trade hub located at the meeting point of the Syr Darya and Arys rivers in present southern Kazakhstan.The researchers investigated the region to determine when the irrigation canals were abandoned and studied the past dynamics of the Arys river, whose waters fed the canals. The abandonment of irrigation systems matches a phase of riverbed erosion between the 10th and 14th century CE, that coincided with a dry period with low river flows, rather than corresponding with the Mongol invasion.The research was led by the University of Lincoln in collaboration with VU University Amsterdam, University College London, the University of Oxford and JSC Institute of Geography and Water Safety, Almaty, Republic of Kazakhstan. It is published in | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215095920.htm | Delayed Arctic ice advance tracked back to atmospheric conditions near Alaska months prior | Experts in Japan recently discovered that atmospheric conditions near Alaska can affect sea ice conditions in the Arctic Ocean months later. The team used various data, including ship-based data from 2018, to uncover how a single atmospheric event over the northern Pacific Ocean caused significantly delayed sea ice formation in the Pacific Arctic region. | "Global warming is going on, so the global mean surface air temperature is increasing, but compared to that trend, the Arctic is warming twice or more as fast," said Assistant Professor Tsubasa Kodaira, first author of the recent research publication and an expert in applied physical oceanography from the University of Tokyo.One important heat source in the Arctic is warm Pacific seawater. The seawater flows northward into the Bering Sea, then through the narrow, 85-kilometer wide opening of the Bering Strait into the Chukchi Sea and onward into the Arctic. Researchers aboard the research vessel Mirai in November 2018 recorded water conditions for 12 consecutive days while sailing along the edge of sea ice in the Chukchi Sea. Despite ideal atmospheric conditions for sea ice formation, researchers recorded that the water surface remained unusually warm and ice-free.The delay of sea ice formation in 2018 was remarkable even in an era of climate change turning extreme weather into regular events. Sea ice coverage of the Chukchi Sea remained 20% less from Nov. 13 through Dec. 4, 2018, compared to the average from 2002 to 2017.The research team analyzed satellite recordings of sea surface temperature of the Chukchi Sea from 2002 to 2018. During the months when sea ice formed, the fluctuations of seawater temperature closely matched fluctuations of the Pacific Decadal Oscillation (PDO) index, large-scale and long-term sea surface temperature variations over northern regions of the Pacific. Despite this two-decade association between Chukchi Sea temperature and the PDO index, when the Chukchi Sea was at its warmest in November 2018, the PDO was neutral.The research team looked specifically at monthly sea surface temperatures from August through November in every year. Typically, seawater temperature cooled by about two degrees each month as summer fades to winter. In 2018, the temperature remained the same as August in September."So, something was happening in summer to create the unusual warm seawater observed by Mirai in November 2018," said Kodaira.Researchers then examined additional atmospheric satellite data recordings and noticed sustained, unusually high air pressure over the Bering Sea in September 2018. This high pressure is known as atmospheric blocking and leads to stationary weather patterns. This atmospheric blocking caused a sustained increase in wind blowing northward over the Bering Strait.Kodaira's team estimates that these winds led to 70% more water than average flowing from the Pacific into the Arctic."This large volume of additional warm Pacific water was likely what prohibited sea ice advance towards the south in November 2018," said Kodaira.Researchers regard the September 2018 Bering Sea atmospheric blocking event as unusual because although such events are common in the region during the winter, they are significantly less common in the summer and autumn.The unusual atmospheric blocking in September and remarkably delayed sea ice formation in November occurred during a year with a neutral PDO index. The study of Kodaira's team also showed that seawater temperatures increase by a full 1 degree Celsius during a positive phase of PDO index.If atmospheric blocking were to occur simultaneously with a positive PDO index, researchers predict sea surface temperatures in the Arctic could rise by approximately 2 degrees Celsius, dramatically reducing -- not just delaying -- annual sea ice growth.The Pacific Arctic region, including the Chukchi Sea, was previously known to have experienced a significant reduction of summer sea ice and this new study has demonstrated one mechanism of how sea ice formation can be delayed. The researchers hope that their new findings will lead to better predictions of Arctic sea ice formation, benefiting global weather forecasting and predictions of local Arctic ecosystem health. | Climate | 2,020 |
December 15, 2020 | https://www.sciencedaily.com/releases/2020/12/201215104320.htm | Fractured bedrock in forests is overlooked source of natural CO2 | The bedrock beneath our feet has a reputation as an inhospitable place. In contrast, soil is known to be teeming with life -- from microbes to plant roots to bugs. | This perspective has set soil up as the most important source of carbon dioxide produced by forests, the COThe study found that COThis finding does not mean that landscapes are emitting more COThe study linked CO"This is paradigm shifting in terms of where the action is," said Daniella Rempe, an assistant professor at the UT Jackson School of Geosciences who coauthored the study. "Soils may not be the only key player in forests."The study was published on Dec.6 in the Alison Tune, a graduate student at the Jackson School, led the research. Other coauthors include Jackson School Professor Philip Bennett, Jia Wang, a graduate student at the University of Illinois Urbana-Champaign, and Jennifer Druhan, an assistant professor at the University of Illinois Urbana-Champaign who played a key role in designing and executing the research.Soil does not sit on top of solid bedrock. Rather, a transition zone of fractured and weathered bedrock sits between these two extremes. This altered rock is notoriously difficult to sample. The research relied on a specialized sampling tool buried in a hill slope in northern California, that extended from the top of the fractured bedrock to the bottom, about 44 feet.This tool quickly revealed that this region was an active site of CO"There is a large COBy analyzing thousands of samples collected from 2017-2019, the researchers discovered that the COThe researchers found that this dissolved COThis study builds on a growing body of knowledge showing fractured bedrock as an ecologically important region. For example, in a 2018 study, Rempe and collaborators found evidence for rock moisture in fractured rock sustaining trees during droughts.Mark Torres, an assistant professor at Rice University who studies how carbon cycles through environments, said that the research is significant because it sheds light on a part of the landscape that is considered a "black box" between the soil and the groundwater."In the work I do, I usually scoop up river water and I have to infer what's going on underneath a hill," he said. "What's really impressive about the work is how they observed things that are incredibly difficult to see."The researchers are planning on investigating fractured bedrock in other places, including a local research site at the Jackson School's White Family Outdoor Learning Center, a 266-acre site in Dripping Springs, Texas."Fractured bedrock is really common in Texas, where the soil is really thin and there's lots of deep rooting," Tune said. "It could be an important part of the carbon cycle in these ecosystems and it could be important to understand that as we go forward and as the climate changes over time."The Department of Energy, the National Science Foundation, and the Geological Society of America supported the research. | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214192406.htm | Trees are out of equilibrium with climate | Forecasts predicting where plants and animals will inhabit over time rely primarily on information about their current climate associations, but that only plays a partial role. | Under climate change, there's a growing interest in assessing whether trees and other species can keep pace with changing temperatures and rainfall, shifting where they are found, also known as their ranges, to track their suitable climates. To test this, a University of Maine-led research team studied the current ranges of hundreds of North American trees and shrubs, assessing the degree to which species are growing in all of the places that are climatically suitable. Researchers found evidence of widespread "underfilling" of these potential climatic habitats -- only 50% on average -- which could mean that trees already have disadvantage as the world continues to warm.Benjamin Seliger, a then UMaine Ph.D. student with the Climate Change Institute, spearheaded the study with his doctoral adviser, Jacquelyn Gill, a UMaine associate professor of paleoecology and plant ecology. Brain McGill, a UMaine professor of biological sciences, and Jens-Christian Svenning, a macroecologist and biogeographer from Aarhus University in Denmark also contributed.The team used species distribution models to assess the degree to which 447 North American trees' and shrubs' "fill" their potential climatic ranges by comparing regions that are climatically suitable, known as potential ranges, against where trees are actually found, or their realized ranges.The Seliger, now a postdoctoral researcher at the Center of Geospatial Analytics at North Carolina State University, and co-authors discovered a significant difference between where the trees they studied could grow, and where they actually grow, also known as range filling. The average range filling value across all 447 species equalled 48.6%, indicating that on average, trees are not found in about half of the areas that are climatically suitable for them, according to researchers."We found tree ranges are more limited by non-climatic factors than expected, suggesting trees may not simply track warming climates." Seliger says.Species distribution models (SDMs) are a common tool to predict how climate change will affect biodiversity and the future ranges of plants and animals. Various studies, including the one from the UMaine-led group, however, caution that because this tool assumes that species live in all areas that are climatically suitable, known as experiencing climatic equilibrium, it may not provide an accurate prediction of where species will be found in the future.An SDM relies on what has been considered a foundational principle, "that geographic ranges generally appear to be in equilibrium with contemporary climate," according to researchers. Growing evidence suggests otherwise for many species, which experience climatic disequilibrium.Seliger and his team found that North American trees and shrubs with large ranges tended to show much stronger evidence of climatic equilibrium, meaning they had high range filling. Small-ranged species, however, had much lower range filling overall, performing worse than predicted by a null model. According to researchers, that means small-ranged tree species, including many rare trees and species the International Union for the Conservation of Nature (IUCN) lists as vulnerable, will face additional challenges as they try to track their climates into the future.The group also found that small-rage species may be more limited by nonclimatic influences, such as soils or pathogens. Conservation efforts for these plants and animals, therefore, should "account for a complex interplay of factors in addition to climate when preparing for the next century of global change," according to researchers.Their findings support a growing body of evidence that for a climatic disequilibrium among various flora. As to what causes the disequilibrium could be due to two factors, according to researchers: dispersal lags that date back to the time when glaciers covered large portions of North American 21,000 years ago, or by non-climatic factors that may influence ranges more than previously appreciated, such as soil, competition with other plants, or symbiosis."It's been thought that if you zoom out to the scale of North America, climate was the most important factor in determining where species would be found. This study reveals some striking gaps in our knowledge; even at the scale of an entire continent, soils or other plants and animals may be playing an important role too. We used to think those were more important at the more local scale -- think of how the trees might change across two areas of your favorite park," Gill says. "All of this means that when it comes to plants, our predictive tools need to get a lot more sophisticated, if they're going to be useful for conservation." | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214192332.htm | Nanoengineered cement shows promise for sealing leaky gas wells | Leaking natural gas wells are considered a potential source of methane emissions, and a new nanomaterial cement mixture could provide an effective, affordable solution for sealing these wells, according to a team of Penn State scientists. | "We have invented a very flexible cement that is more resistant to cracking," said Arash Dahi Taleghani, associate professor of petroleum engineering at Penn State. "That's important because there are millions of orphaned and abandoned wells around the world, and cracks in the casings can allow methane to escape into the environment."When natural gas wells are drilled, cement is used to secure the pipe, or casing, to the surrounding rock, creating a seal that prevents methane from migrating into the shallow subsurface, where it could enter waterways, or the atmosphere, where it is a potent greenhouse gas, the scientists said.Wells can extend miles underground and over time changing temperatures and pressures can degrade the cement, causing cracks to form. The scientists said repairs involve injecting cement in very narrow areas between the casing and rock, requiring special cement."In construction, you may just mix cement and pour it, but to seal these wells you are cementing an area that has the thickness of less than a millimeter, or that of a piece of tape," Dahi Taleghani said. "Being able to better pump cement through these very narrow spaces that methane molecules can escape from is the beauty of this work."Adding almost 2D graphite created a cement mixture that better filled these narrow spaces and that was also stronger and more resilient, the scientists found. They recently reported their findings in the The scientists developed a multi-step process to uniformly distribute sheets of the nanomaterial into a cement slurry. By treating the graphite first with chemicals, the scientists were able to change its surface properties so the material would dissolve in water instead of repelling it."If we just pour this material in the water and mix it, these small particles have a tendency to stick together and form a conglomerate," Dahi Taleghani said. "If they are not dispersing evenly then the graphite is not as strong inside the cement."The cement mixture can be used in active unconventional wells like those found in the Marcellus Shale gas play, or to seal orphaned and abandoned gas wells, the scientists said. It also shows promise for use in carbon dioxide capture and storage technology.Graphite is more affordable than other nanomaterials previously used to bolster cement performance. In addition, very little of the material is needed to strengthen the cement, the scientists said."Considering the low cost of the amount of graphite nanoplatelets required for this test, this technology may provide an economic solution for industry to address possible cementing problems in the field," Dahi Taleghani said. | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214164341.htm | Critical temperature for tropical tree lifespan revealed | For the first time scientists have provided clear evidence that tropical tree lifespan decreases above a critical temperature threshold. | Findings, published today (14 December) in the journal As temperatures are rising rapidly across large parts of the tropics, tree mortality is likely to accelerate in substantial parts of the tropics, including the Amazon, Pantanal and Atlantic forests with implications for animal habitats, air quality and carbon stocks.Although tropical rainforests account for only 7% of all land, they are home to about 50% of all animal and plant species, and approximately 50 % of forest carbon stocks on earth. Thus small changes in the functioning of tropical forests can significantly change the atmospheric levels of COProfessor Manuel Gloor and Dr Roel Brienen, of Leeds' School of Geography, are co-authors of the new study.Professor Gloor said: "Many regions in the tropics are heating up particularly rapidly and substantial areas will become warmer, on average, than approximately 25 C."Our findings -- which are the first to demonstrate that there is a temperature threshold -- suggests that for trees in these regions, their longevity is likely to be negatively affected."Dr Brienen added: "This indicates that tropical forests may be more vulnerable to increasing heat than has been previously thought. As a result of global warming, we therefore expect a shortening of tree lifespans in the tropics."These results are a warning sign that, along with deforestation, global warming adds extra stress on the Earth's tropical forests."The research team, led by Dr Giuliano Locosselli, from the Institute of Biosciences, University of São Paulo, Brazil, spent four years examining tree-ring data from more than 100,000 trees worldwide belonging to 400 different tree species from 3,000 sites across the globe.Dr Locosselli said: "In the tropics, trees grow, on average, twice as fast as those in cooler regions of the world. But they also have a shorter average lifespan of 186 years, compared to 322 years of trees in other climates. Our analysis suggests that the life-spans in the tropics will likely decrease further still."If tropical trees die earlier, this will affect how much carbon these forests can hold, raising concerns about the future potential of forests to offset COCurrently, average temperatures in tropical rainforests vary between 21 C and 30 C. According to the latest forecasts, tropical temperatures on land will continue to rise, reaching on average a combined 2.5 C above pre-industrial levels over the next 10 to 20 years. The study also shows that temperature effects on tree longevity will be further exacerbated by dry conditions.Climate change will also have an impact on tropical rainforests outside of South America, such as the Congo Forest in west Africa -- the second largest tropical forest in the world after the Amazon.Dr Locosselli added: "While tropical rainforests in the Amazon are already close to this temperature threshold temperatures in the Congo are lower. But, with this great increase in temperature, we might begin to see signs of increased tree mortality. From this point of view, the scenario is quite bleak."Professor Marcos Buckeridge, Director of the Biosciences Institute of the University of São Paulo, who is also a co-author of the study, added: "Temperatures will keep rising in the near future even if we were to take drastic emissions reductions measures."Thus it is unavoidable that the critical threshold for tree longevity will increasingly be exceeded in the tropics and thus it is even more important to protect tropical forests and curb greenhouse emissions." | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214150352.htm | Mapping corals from the sky guides reef conservation | Coral reefs are one of the most biodiverse ecosystems on the planet supporting an estimated 25 percent of all marine species. These biologically rich ecosystems are threatened by multiple stressors, from warming ocean temperatures brought on by climate change to increases in water pollution from coastal development. According to current estimates, 75 percent of the world's coral reefs could face critical threat levels by 2050. Scientists widely agree that immediate and well-targeted action must be taken to preserve coral reefs for future generations. However, without a clear understanding of where live corals are found, management and conservation efforts will remain hampered at best and ineffective at worst. | Previous work to assess live coral cover has been constrained by technical limitations inherent to available surveillance approaches. For instance, detailed field-based surveys are geographically limited, while satellites cannot track corals at resolutions detailed enough for many types of management activities. Airborne technologies, however, can collect enormous tracts of contiguous high-resolution data within a single survey, providing insights into both coral health and extent. If the resulting maps can indicate the location of live corals, then specific strategies can be created to preserve, protect, and restore them.A critical case in point is the Hawaiian Islands, an icon of the natural world and the modern-day stresses underway on reef ecosystems. Coastal development has resulted in hotspots of sedimentation, waterborne pollutants, and reef removal, while fishing and other resource uses have generated declines in reef resilience. Marine heatwaves, driven by a warming global climate, have also periodically engulfed the Hawaiian Islands, with the 2015 and 2019 coral bleaching events being the most recent. The 2015 event caused widespread coral death, but the geographic extent of coral loss or resistance has remained poorly understood, as it has in reef regions throughout the world.Using a new airborne mapping approach developed by researchers at Arizona State University's Center for Global Discovery and Conservation Science (GDCS), the geographic distribution of live corals was, for the first time, quantified to 16 meters (51 feet) of water depth across the main Hawaiian islands. The study was published today in "We undertook this first-ever mapping of a large archipelago to determine where corals live in Hawaiian waters despite repeated heatwaves and problematic coastal development issues," said Greg Asner, lead author of the study and director of GDCS. "It's this basic information that is needed by partner organizations to drive more cost-effective protections, restoration activities, and public engagement."The mapping data were collected by the ASU Global Airborne Observatory, an aircraft-based laboratory developed by Asner and his team that houses advanced Earth mapping technology. By combining laser-guided imaging spectroscopy and artificial intelligence, the new approach reveals unprecedented views of coral reefs below the ocean surface. The maps show where live corals persist as well as areas of degraded reef."Operational mapping of live coral cover within and across Hawaii's reef ecosystems affords opportunities for managers and policy-makers to better address reef protection, resilience, and restoration," said Brian Neilson, head of Hawaii's Division of Aquatic Resources and study co-author. "With these new maps, we have a better shot at protecting what we have while focusing on where to improve conditions for corals and the myriad of species that depend upon corals."The team's mapping of live corals was integrated with geospatial information on coastal and marine activities, and computer algorithms were used to estimate which factors most closely predict where corals are currently found on Hawaiian reefs. The results of the analysis revealed that nearshore development has a major negative relationship with live corals."Never before has there been such a detailed and synoptic view of live corals at this scale," said co-author Jamison Gove of the National Oceanic and Atmospheric Administration. "These findings are foundational for developing place-based conservation and management strategies to promote reef persistence and mitigate further losses in corals across Hawaii."The new mapping approach also pointed out areas where corals show resilience to human-driven environmental stressors. These regions of coral survival, deemed 'refugia', suggest that some corals and some sites are more resilient, and are thus prime locations for enhanced coral conservation. Garnering a greater understanding of coral survivorship could also alter predictions of whether corals will survive in the current and future ocean climate."We are trying to make major leaps on the science and technology side to directly address coral reef conservation and management challenges, starting in the Hawaiian Islands," said Asner. "Our hope is that these outcomes will grow the discussion among communities, environmental managers, and elected officials, without which, we will continue to lose coral reefs right before our eyes." | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214123512.htm | Chance played a major role in keeping Earth fit for life | A study by the University of Southampton gives a new perspective on why our planet has managed to stay habitable for billions of years -- concluding it is almost certainly due, at least in part, to luck. The research suggests this may shorten the odds of finding life on so-called 'twin-Earths' in the Universe. | The research, published in the Nature journal Geological data demonstrate that Earth's climate has remained continuously habitable for more than three billion years. However, it has been precariously balanced, with the potential to rapidly deteriorate to deep-frozen or intolerably hot conditions causing planet-wide sterility.Professor Toby Tyrrell, a specialist in Earth System Science at the University of Southampton, explains: "A continuously stable and habitable climate on Earth is quite puzzling. Our neighbours, Mars and Venus, do not have habitable temperatures, even though Mars once did. Earth not only has a habitable temperature today, but has kept this at all times across three to four billion years -- an extraordinary span of geological time."Many events can threaten the continuous stability of a planet -- asteroid impacts, solar flares and major geological events, such as eruptions of supervolcanoes. Indeed, an asteroid which hit the Earth 66 million years ago caused the extinction of more than 75 per cent of all species, killing off the dinosaurs along with many other species.Previous computer modelling work on Earth habitability has involved modelling a single planet: Earth. But, inspired by discoveries of exoplanets (those outside of our solar system) that reveal that there are billions of Earth-like planets in our galaxy alone, a Southampton scientist took a novel approach to investigating a big question: what has led Earth to remain life-sustaining for so long?To explore this, Professor Tyrrell tapped into the power of the University of Southampton's Iridis supercomputing facility to run simulations looking at how 100,000 randomly different planets responded to random climate-altering events spread out across three billion years, until they reached a point where they lost their habitability. Each planet was simulated 100 times, with different random events each time.Having accrued a vast set of results, he then looked to see whether habitability persistence was restricted to just a few planets which were always capable of sustaining life for three billion years, or instead was spread around many different planets, each of which only sometimes stayed habitable for this period.The results of the simulation were very clear. Most of those planets which remained life-sustaining throughout the three billion year period only had a probability, not a certainty, of staying habitable. Many instances were of planets which usually failed in the simulations and only occasionally remained habitable. Out of a total population of 100,000 planets, nine percent (8,700) were successful at least once -- of those, nearly all (about 8,000) were successful fewer than 50 times out of 100 and most (about 4,500) were successful fewer than 10 times out of 100.The study results suggest chance is a major factor in determining whether planets, such as Earth, can continue to nurture life over billions of years. Professor Tyrrell concludes: "We can now understand that Earth stayed suitable for life for so long due, at least in part, to luck. For instance, if a slightly larger asteroid had hit Earth, or had done so at a different time, then Earth may have lost its habitability altogether."To put it another way, if an intelligent observer had been present on the early Earth as life first evolved, and was able to calculate the chances of the planet staying habitable for the next several billion years, the calculation may well have revealed very poor odds."Given these seemingly poor odds, the study speculates that elsewhere in the Universe there should be Earth-like planets which had similar initial prospects but which, due to chance events, at one point became too hot or too cold and consequently lost the life upon them. As techniques to investigate exoplanets improve, and what seem at first to be 'twin Earths' are discovered and analysed, it seems likely that most will be found to be uninhabitable. | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214123447.htm | Oregon's Western Cascades watershed to experience larger, more frequent fires | The Clackamas Basin rarely experiences the intense fire activity that burned in the watershed during the Labor Day fires, but new research out of Portland State University shows that wildfires like the Riverside Fire, which grew to 138,000 acres within days, could become more common under a warming climate, even under non-extreme wind conditions. | The study found that wildfire hazard in the Clackamas Basin, which is the second largest source of drinking water for the Portland metro area, will likely increase by mid-century. Projected changes in temperature and relative humidity are expected to lead to longer fire seasons and more severe fire weather in Oregon's Western Cascade mountains, which in turn will result in larger, more frequent fires."Because of shifts in climate, the scenarios that would create extreme fire events all become a little more plausible," said Andy McEvoy, the study's lead author and a graduate student in environmental science and management. "There will be that many more days under which those components of a fire -- ignition, weather and fuel -- can align in a terrible way."The group of researchers simulated four climate scenarios from 2040-2069, representing a range of plausible changes in temperature and humidity.The simulations showed that the fire season increased from as little as eight days to as much as 32 days. The projected annual average area burned increased significantly by 50% under the least impactful scenario (the coolest and wettest of the four) and as much as 540% under the most extreme scenario (the hottest and driest of the four)."We don't make the case that one future is more likely than the other, but it helps bracket the plausible outcomes for planning purposes," said McEvoy, who works as a research fellow in the U.S. Forest Service's Pacific Northwest Research Station. "The future is very uncertain and if land and resource managers plan just for the average case, their plans are not going to be robust in the face of those worst-case scenarios."The researchers, who worked closely with the Clackamas River Water Providers and the Clackamas County Water and Environment Services, said the findings provide regional managers and planners with a tool to develop climate adaptation and risk mitigation strategies. Given the wide range of plausible future wildfire hazards, robust adaptation plans will be ones that maintain essential ecosystem services across the broadest range of scenarios by balancing land use management, fire suppression, and community preparedness strategies.These efforts could range from designing and testing the effectiveness of fuel breaks -- breaks in vegetation that can help firefighters control the spread of fire and protect homes and resources -- to identifying susceptible communities and planning evacuations in the event of future extreme wildfires. In those cases, like the Riverside Fire, fuel breaks would not be successful and the only sensible strategy would be timely, safe evacuations."They're planning for an uncertain future," McEvoy said. "They have to plan using all available tools and adapt to events as they occur." | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214104716.htm | The moon controls the release of methane in Arctic Ocean | It may not be very well known, but the Arctic Ocean leaks enormous amounts of the potent greenhouse gas methane. These leaks have been ongoing for thousands of years but could be intensified by a future warmer ocean. The potential for this gas to escape the ocean, and contribute to the greenhouse gas budget in the atmosphere, is an important mystery that scientists are trying to solve. | The total amount of methane in the atmosphere has increased immensely over the past decades, and while some of the increase can be ascribed to human activity, other sources are not very well constrained.A recent paper in The moon controls one of the most formidable forces in nature -- the tides that shape our coastlines. Tides, in turn, significantly affect the intensity of methane emissions from the Arctic Ocean seafloor."We noticed that gas accumulations, which are in the sediments within a meter from the seafloor, are vulnerable to even slight pressure changes in the water column. Low tide means less of such hydrostatic pressure and higher intensity of methane release. High tide equals high pressure and lower intensity of the release" says co-author of the paper Andreia Plaza Faverola."It is the first time that this observation has been made in the Arctic Ocean. It means that slight pressure changes can release significant amounts of methane. This is a game-changer and the highest impact of the study." Says another co-author, Jochen Knies.Plaza Faverola points out that the observations were made by placing a tool called a piezometer in the sediments and leaving it there for four days.It measured the pressure and temperature of the water inside the pores of the sediment. Hourly changes in the measured pressure and temperature revealed the presence of gas close to the seafloor that ascends and descends as the tides change. The measurements were made in an area of the Arctic Ocean where no methane release has previously been observed but where massive gas hydrate concentrations have been sampled."This tells us that gas release from the seafloor is more widespread than we can see using traditional sonar surveys. We saw no bubbles or columns of gas in the water. Gas burps that have a periodicity of several hours won't be identified unless there is a permanent monitoring tool in place, such as the piezometer." Says Plaza FaverolaThese observations imply that the quantification of present-day gas emissions in the Arctic may be underestimated. High tides, however, seem to influence gas emissions by reducing their height and volume."What we found was unexpected and the implications are big. This is a deep-water site. Small changes in pressure can increase the gas emissions but the methane will still stay in the ocean due to the water depth. But what happens in shallower sites? This approach needs to be done in shallow Arctic waters as well, over a longer period. In shallow water, the possibility that methane will reach the atmosphere is greater." Says Knies.High sea-level seems thus to influence gas emissions by potentially reducing their height and volume. The question remains whether sea-level rise due to global warming might partially counterbalance the effect of temperature on submarine methane emissions."Earth systems are interconnected in ways that we are still deciphering, and our study reveals one of such interconnections in the Arctic: The moon causes tidal forces, the tides generate pressure changes, and bottom currents that in turn shape the seafloor and impact submarine methane emissions. Fascinating!" says Andreia Plaza FaverolaThe paper is the result of a collaboration between CAGE, Centre for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway, and Ifremer under the project SEAMSTRESS -- Tectonic Stress Effects on Arctic Methane Seepage | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214104648.htm | Applying compost to landfills could have environmental benefits | Many people think of composting organic matter as a way of keeping solid waste out of landfills, but a new study from North Carolina State University finds there can be significant environmental benefits associated with using compost at landfills. | "There are an increasing number of composting programs out there, and many of them are required to use the resulting compost 'beneficially,'" says James Levis, corresponding author of the study and a research assistant professor of civil, construction and environmental engineering at NC State. "A lot of state and local regulations don't recognize 'alternative daily cover' as a beneficial use. But our work shows that using compost as alternative daily cover at landfills is competitive, and often superior, to the use of compost as a soil amendment in terms of its environmental benefits."Landfills apply a layer of daily cover each day in order to reduce odors, reduce wind-blown debris and keep vermin out of the landfilled waste. Federal regulations currently require six inches of soil as a daily cover.Meanwhile, while most of the nation's yard waste is already turned into compost, a small and rapidly growing percentage of its food waste is also being composted. However, compost from food waste often contains broken glass and other contaminants, making it unsuitable for most soil amendments, such as use in gardens or agricultural fields. There are technologies available to remove contaminants, but these increase the cost of composting. In addition, there is not always a sufficient local market for all of the available compost.Levis and his collaborators wanted to determine how environmentally beneficial it would be to use compost as alternative daily cover on landfills, and whether those benefits were comparable to the benefits of using compost to amend soil.To that end, the researchers developed a complex computational model to predict the overall environmental impact of two defined cases: the use of compost to amend soil (e.g., in your garden) and the use of compost as a daily cover in landfills. The model ran simulations evaluating the entire life cycle of each case. For example, they not only looked at greenhouse gases released by compost, but at greenhouse gas emissions from the equipment that applies compost at landfill facilities. The simulations also accounted for decreases in emissions, such as reduced emissions related to fertilizer use when growers use compost in their soil instead of conventional fertilizers.Specifically, the model looked at five environmental impacts:The researchers ran a range of simulations in order to account for both uncertainty and the wide variety of different circumstances under which the two cases might take place.The researchers found that using compost as daily cover outperformed its use as a soil amendment in almost 100% of the simulations evaluated when it comes to eutrophication. Daily cover also did more to reduce acidification in 77% of simulations and reduced global warming potential 63% of the time. On the other hand, soil amendment was better at limiting abiotic resource depletion potential in 96% of the simulations, and was better in terms of cumulative energy demand about 94% of the time, primarily due to the reduction of peat use."Our work also highlights the circumstances that make one process more environmentally attractive than the other," says Mojtaba Sardarmehni, first author of the study and a Ph.D. student at NC State. "For example, our work shows which variables are relevant when determining whether using compost as daily cover in a landfill will reduce global warming potential, as compared to using compost to amend soil.""We are not suggesting that compost should necessarily be used as alternative daily cover instead of to amend soil," Levis says. "But we think this work highlights the fact that there are environmental benefits associated with using compost as daily cover at landfills -- and we need decision-makers to consider that." | Climate | 2,020 |
December 14, 2020 | https://www.sciencedaily.com/releases/2020/12/201214192358.htm | Planning ahead protects fish and fisheries | Conservation of fish and other marine life migrating from warming ocean waters will be more effective and also protect commercial fisheries if plans are made now to cope with climate change, according to a Rutgers-led study in the journal | "Sticking our heads in the sand doesn't work," said lead author Malin Pinsky, an associate professor in the Department of Ecology, Evolution, and Natural Resources in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. "Effective ocean planning that accounts for climate change will lead to better safeguards for marine fish and commercial fisheries with few tradeoffs."As the ocean becomes busier with shipping, energy development, fishing, conservation, recreation and other uses, planning efforts that set aside parts of the ocean for such uses have begun on all seven continents. But these efforts typically do not plan ahead for the impacts of climate change despite establishing plans that can last for many decades.With ocean waters warming, many commercially valuable fish species could move hundreds of miles northward toward colder water in the years ahead. Such movement is already underway -- in some cases dramatically -- substantially disrupting fisheries and exacerbating international fisheries conflicts.Researchers led by Pinsky focused on the costs and benefits of planning ahead for the impacts of climate change on marine species. They simulated the ocean planning process in the United States and Canada for conservation zones, fishing zones and wind and wave energy development zones. Then they looked at nearly 12,000 different projections for where 736 species around North America will move during the rest of this century. They also looked at potential tradeoffs between meeting conservation and sustainable fishing goals now versus in 80 years."We were worried that planning ahead would require setting aside a lot more of the ocean for conservation or for fishing, but we found that was not the case," Pinsky said. "Instead, fishing and conservation areas can be set up like hopscotch boxes so fish and other animals can shift from one box into another as they respond to climate change. We found that simple changes to ocean plans can make them much more robust to future changes. Planning ahead can help us avoid conflicts between, for example, fisheries and wind energy or conservation and fisheries."While the study focused on long-term changes, many fisheries decisions are focused on near-term changes -- one to a few years ahead, Pinsky said. So the scientists are now testing whether they can forecast near-term shifts in where species are found so fisheries can adapt more easily to species on the move.While climate change will severely disrupt many human activities and "complete climate-proofing is impossible, proactively planning for long-term ocean change across a wide range of sectors is likely to provide substantial benefits," the study says. | Climate | 2,020 |
December 10, 2020 | https://www.sciencedaily.com/releases/2020/12/201210145757.htm | What caused the ice ages? Tiny ocean fossils offer key evidence | The last million years of Earth history have been characterized by frequent "glacial-interglacial cycles," large swings in climate that are linked to the growing and shrinking of massive, continent-spanning ice sheets. These cycles are triggered by subtle oscillations in Earth's orbit and rotation, but the orbital oscillations are too subtle to explain the large changes in climate. | "The cause of the ice ages is one of the great unsolved problems in the geosciences," said Daniel Sigman, the Dusenbury Professor of Geological and Geophysical Sciences. "Explaining this dominant climate phenomenon will improve our ability to predict future climate change."In the 1970s, scientists discovered that the concentration of the atmospheric greenhouse gas carbon dioxide (CONow, an international collaboration led by scientists from Princeton University and the Max Planck Institute for Chemistry (MPIC) have found evidence indicating that during ice ages, changes in the surface waters of the Antarctic Ocean worked to store more COFor decades, researchers have known that the growth and sinking of marine algae pumps COThe potential for a reduction in wind-driven upwelling to keep more COThe Princeton-MPIC collaboration has developed such an approach, using tiny diatoms. Diatoms are floating algae that grow abundantly in Antarctic surface waters, and their silica shells accumulate in deep sea sediment. The nitrogen isotopes in diatoms' shells vary with the amount of unused nitrogen in the surface water. The Princeton-MPIC team measured the nitrogen isotope ratios of the trace organic matter trapped in the mineral walls of these fossils, which revealed the evolution of nitrogen concentrations in Antarctic surface waters over the past 150,000 years, covering two ice ages and two warm interglacial periods."Analysis of the nitrogen isotopes trapped in fossils like diatoms reveals the surface nitrogen concentration in the past," said Ellen Ai, first author of the study and a Princeton graduate student working with Sigman and with the groups of Alfredo Martínez-García and Gerald Haug at MPIC. "Deep water has high concentrations of the nitrogen that algae rely on. The more upwelling that occurs in the Antarctic, the higher the nitrogen concentration in the surface water. So our results also allowed us to reconstruct Antarctic upwelling changes."The data were made more powerful by a new approach for dating the Antarctic sediments. Surface water temperature change was reconstructed in the sediment cores and compared with Antarctic ice core records of air temperature."This allowed us to connect many features in the diatom nitrogen record to coincident climate and ocean changes from across the globe," said Martínez-García. "In particular, we are now able to pin down the timing of upwelling decline, when climate starts to cool, as well as to connect upwelling changes in the Antarctic with the fast climate oscillations during ice ages."This more precise timing allowed the researchers to home in on the winds as the key driver of the upwelling changes.The new findings also allowed the researchers to disentangle how the changes in Antarctic upwelling and atmospheric CO"Our findings show that upwelling-driven atmospheric COTheir findings also have implications for predicting how the ocean will respond to global warming. Computer models have yielded ambiguous results on the sensitivity of polar winds to climate change. The researchers' observation of a major intensification in wind-driven upwelling in the Antarctic Ocean during warm periods of the past suggests that upwelling will also strengthen under global warming. Stronger Antarctic upwelling is likely to accelerate the ocean's absorption of heat from ongoing global warming, while also impacting the biological conditions of the Antarctic Ocean and the ice on Antarctica."The new findings suggest that the atmosphere and ocean around Antarctica will change greatly in the coming century," said Ai. "However, because the CO | Climate | 2,020 |
December 10, 2020 | https://www.sciencedaily.com/releases/2020/12/201210145726.htm | Bacteria release climate-damaging carbon from thawing permafrost | Around a quarter of the ground in the northern hemisphere is permanently frozen. These areas are estimated to contain about twice as much carbon as the world's current atmosphere. New research says that these permafrost soils are not only increasingly thawing out as the Earth becomes warmer, but also releasing that carbon, which accelerates the thawing. | An international research team that includes Thomas Borch, Colorado State University professor in the Department of Soil and Crop Sciences, and Monique Patzner, a Ph.D. student at the University of Tübingen's Center for Applied Geoscience in Germany, has investigated the way this development affects the microorganisms in the soil. Their results have been published in The work was led by Andreas Kappler of the University of Tübingen and Casey Bryce at the University of Bristol in the UK.The team worked on the assumption that thawing increases the availability of organic carbon for microorganisms to process, in turn releasing vast amounts of carbon dioxide and methane. These gases accelerate the greenhouse effect, leading to further permafrost thawing in a vicious cycle.Rising temperatures lead to collapse of intact permafrost soils, resulting in landslides and the widespread formation of wetlands. In this latest study, the team investigated what happens to the carbon trapped in the soil when the permafrost thaws out."The organic material naturally present in the samples accumulated as peat over thousands of years. With permafrost thaw, microbes become active and are able to decompose the peat," Kappler said. "We also know that iron minerals preserve organic carbon from biodegradation in various environments -- and thus they could be a carbon sink even after the permafrost has thawed."The reactive iron is present as a kind of rust and might be expected to trap the organic material in what the scientists call a "rusty carbon sink."The team investigated the storage potential of the rusty carbon sink at a permafrost peatland at Stordalen mire, Abisko, Sweden. There, samples of the soil porewater and drill cores of the active layer were taken along a permafrost thaw gradient. The research team examined how much organic material was bound to reactive iron minerals, how stable these iron-carbon associations are with permafrost thaw, and whether the microorganisms present could use the material as a source of food and energy. The team also carried out experiments in the laboratory in Tübingen.Borch's team was responsible for characterization of the iron mineralogy along the permafrost thaw gradient using synchrotron-based radiation at the Stanford Synchrotron Radiation Lightsource. They observed a loss of poorly crystalline iron and a decrease in organic matter-chelated iron, but an increase in iron-bearing clays and iron sulfurs along the thaw gradient."This clearly indicated that important iron phases were dissolving due to permafrost thaw-induced anaerobic conditions," Borch said.The team found that microorganisms are apparently able to use the iron as a food source, thereby releasing the bound organic carbon into the water in the soil."That means the rusty carbon sink cannot prevent the organic carbon from escaping from the thawing permafrost," Kappler said. "Based on data available from elsewhere in the northern hemisphere, we expect that our findings are applicable for permafrost environments worldwide," added BrycePatzner explained that the rusty carbon sink is only found in intact permafrost soils and is lost during permafrost thaw. Now the researchers are seeking to find out how this facilitates greenhouse gas emissions and thus global warming."It appears that the previously iron-bound carbon is highly bioavailable and, therefore, bacteria could immediately metabolize it into greenhouse gas emissions," Patzner said. "This is a process which is currently absent from climate-change prediction models and must be factored in."The Borch lab is now using Fourier transform ion cyclotron resonance mass spectrometry at the National High Magnetic Field Laboratory to elucidate the chemical nature and fate of the organic matter released. These further inquiries should help improve understanding of carbon cycling in these sensitive ecosystems, Borch said. | Climate | 2,020 |
December 10, 2020 | https://www.sciencedaily.com/releases/2020/12/201210120349.htm | Low oxygen levels in lakes and reservoirs may accelerate global change | Because of land use and climate change, lakes and reservoirs globally are seeing large decreases in oxygen concentrations in their bottom waters. It is well-documented that low oxygen levels have detrimental effects on fish and water quality, but little is known about how these conditions will affect the concentration of carbon dioxide and methane in freshwaters. | Carbon dioxide and methane are the primary forms of carbon that can be found in the Earth's atmosphere. Both of these gases are partially responsible for the greenhouse effect, a process that increases global air temperatures. Methane is 34 times more potent of a greenhouse gas than carbon dioxide, so knowing how low oxygen levels within lakes and reservoirs affect both carbon dioxide and methane could have important implications for global warming.Until now, researchers did not have any empirical data from the whole-ecosystem scale to definitively say how changing oxygen can affect these two greenhouse gases."We found that low oxygen levels increased methane concentrations by 15 to 800 times at the whole-ecosystem scale," said Alexandria Hounshell, a postdoctoral researcher in the Department of Biological Sciences in the College of Science. "Our work shows that low oxygen levels in the bottom waters of lakes and reservoirs will likely increase the global warming potential of these ecosystems by about an order of magnitude."Virginia Tech researchers just published these findings in a high-impact paper in To determine a correlation between oxygen and methane concentrations, researchers honed in on two reservoirs outside of Roanoke. In collaboration with the Western Virginia Water Authority, the research team operated an oxygenation system in Falling Creek Reservoir, which pumps oxygen into the bottom waters and allows researchers to study oxygen concentrations on a whole-ecosystem scale. By also monitoring Beaverdam Reservoir, an upstream reservoir without an oxygenation system, they were able to compare greenhouse gas concentrations in the bottom waters of both reservoirs. They ran the experiment over three years to see how consistent their findings were over time."Methane levels were much higher when there was no oxygen in the bottom waters of these reservoirs; whereas the carbon dioxide levels were the same, regardless of oxygen levels," said Cayelan Carey, associate professor of biological sciences and affiliated faculty member of the Global Change Center. "With low oxygen levels, our work shows that you'll get higher production of methane, which leads to more global warming in the future."This study was one of the first to experimentally test at the whole ecosystem-scale how different oxygen levels affect greenhouse gases. Logistically, it is extremely challenging to manipulate entire ecosystems due to their complexity and many moving parts. Even though scientists can use computer modelling and lab experiments, nothing is as definitive as the real thing."We were able to do a substitution of space for time because we have these two reservoirs that we can manipulate and contrast with one another to see what the future may look like, as lower bottom water oxygen levels become more common. We can say with high certainty that we are going to see these lakes become bigger methane emitters as oxygen levels decrease," said Carey.According to Hounshell, the strength of their results lie in the study's expanse over multiple years. Despite having a range of meteorological conditions over the three years, the study affirmed that much higher methane concentrations in low oxygen conditions happen consistently every year, no matter the air temperature.Ultimately, this study is crucial for how researchers, and the general public, think about how freshwater ecosystems produce greenhouse gases in the future. With low oxygen concentrations increasing in lakes and reservoirs across the world, these ecosystems will produce higher concentrations of methane in the future, leading to more global warming.Of course, these ecological changes are not just happening in the Roanoke region. Around the globe, a number of studies have pointed to changing carbon cycling in terrestrial and marine ecosystems. However, this study is one of the few to address this phenomenon in lakes and reservoirs, which are often neglected in carbon budgets. This study will fill in these knowledge gaps and shine a spotlight on what we can do as citizens to solve this problem.This study suggests that keeping lakes from experiencing low oxygen concentrations in the first place could further prevent them from hitting the tipping point, when they start to become large methane producers. Small decisions can add up. For example, decreasing runoff into lakes and reservoirs can prevent the depletion of oxygen in their bottom waters. "Don't put a ton of fertilizer on your lawn, and be really strategic about how much fertilizer you use and how you use it," said Hounshell.And greenhouse gases are just a small part of the bigger picture of how reservoirs function in the global carbon cycle. Currently, the research team is conducting follow-up oxygen manipulation studies to elucidate other components that contribute to ecosystem change. They will continue to monitor oxygen manipulations in the two Roanoke reservoirs to see how the reservoir can affect the ecosystem for the long haul.This project was funded by the Virginia Tech Institute for Critical Technology and Applied Science, the Fralin Life Sciences Institute at Virginia Tech, and by National Science Foundation grant DEB-1753639. | Climate | 2,020 |
December 10, 2020 | https://www.sciencedaily.com/releases/2020/12/201210112128.htm | One-two punch: Sea urchins stuck belly-up in low-oxygen hot water | As oceans warm and become more acidic and oxygen-poor, Smithsonian researchers asked how marine life on a Caribbean coral reef copes with changing conditions. | "During my study, water temperatures on reefs in Bocas del Toro, Panama, reached an alarming high of almost 33 degrees C (or 91 degrees F), temperatures that would make most of us sweat or look for air conditioning -- options not available to reef inhabitants," said Noelle Lucey, post-doctoral fellow at the Smithsonian Tropical Research Institute (STRI).Lucey and her team showed that when temperatures were at their highest, oxygen levels were lowest and the water was most acidic. These stressful times for reef animals occurred at night when scientists do not typically make observations.To test the responses of sea urchins to these alarming conditions, they designed experiments to separate the effects of acidity (pH), oxygen and temperature. Conditions in the ocean change quickly, so the experiments were designed to reflect this, and they only exposed the animals to different sets of conditions for two hours at a time.The area of the study encompassed an entire bay and nearby, offshore waters. In that area, Hospital Point reef is one of the best places to collect the rock boring sea urchin, "The urchins are so common there you don't even think about putting your foot down," said STRI Fellow Eileen Haskett, a co-author. "When the surf isn't too rough, you can see them hiding in every crevice and reef crack, happily pounded by the waves. When the sunlight hits them perfectly, they shimmer with bright purple and red colors."Lucey and Haskett collected hundreds of urchins. In the laboratory at STRI's Bocas del Toro Research Station, they exposed these prickly creatures for two hours to the severe hot, hypoxic and acidic conditions sea urchins may experience on local reefs.After their exposure to high temperatures, acidity, low oxygen or combinations of the three, the researchers flipped the urchins upside down. When a sea urchin is flipped, it usually immediately rights itself, using its spines and tube feet. In nature, if they do not right themselves quickly, they may get tossed against the rocks by the surf or eaten by reef fish.The experiment clearly showed that it was much harder for sea urchins to right themselves after being in oxygen-poor water. More acid conditions did not seem to affect the urchins' behavior. However, sea urchins were also less able to find their footing and flip right-side up after exposures to high temperatures. Most survived and were returned to the reef but the low oxygen and high temperature exposures resulted in some mortality.The researchers conclude that ocean acidification may not be nearly as important as lack of oxygen (hypoxia), a factor that has not received as much attention in discussions of global climate change. In fact, even though high temperatures, acidity and low oxygen occur at the same time, the team found that together they did not affect the urchin's performance any more than lack of oxygen alone."What really caught my attention was the relationship between extreme low oxygen and high temperatures even out at the offshore sites," Lucey said. "It shouldn't be surprising because the relationship between increasing temperatures and decreasing oxygen is well known, but it is somehow eerie to find this in your own data, in your own little part of the world.""More and more often, tropical reefs experience severe conditions that, as we have shown, push the limits of marine organisms," said Rachel Collin, STRI staff scientist and co-author. "A lack of oxygen and high temperatures are bad news for these reef animals. These severe conditions are occurring more frequently and for longer periods of time, upping the stress levels experienced by important reef organisms like sea urchins.""Showing how animals react to several forms of stress at the same time helps us understand how marine life is affected by changing conditions, and what conditions to look out for," Lucey said. "We were surprised to find that such hot, hypoxic and acidic conditions all occur even on a reef that gets plenty of wave action. Our realistic experiments are alarming -- showing the levels of oxygen already occasionally found on this reef have such a negative impact on these sea urchins." | Climate | 2,020 |
December 9, 2020 | https://www.sciencedaily.com/releases/2020/12/201209170645.htm | Symbiotic relationship between California oaks and mutualist fungi as a buffer for climate change | "Happy families are all alike; each unhappy family is unhappy in its own way." So goes the first line of Leo Tolstoy's "Anna Karenina." Little did the Russian novelist know his famous opening line would one day be used to describe microbial communities, their health and their relationships to their hosts. | It's this idea that an unhealthy or stressed host to a microbiome has a more diverse microbiome than its healthy counterpart," said UC Santa Barbara ecologist An Bui, a graduate student researcher in the lab of theoretical ecologist Holly Moeller. The diversity, she said, is a response to variable conditions that may in turn indicate an unstable or stressed environment. "Healthy hosts are probably going to have very similar microbiomes," she said, "while unhealthy hosts are different in their own ways."Bui and colleagues recently put the Anna Karenina hypothesis to the test in California's Tehachapi mountains as they sought to understand how climate change might affect fungal communities in woodland soil in a future California."Fungi are really important for woodland systems," said Bui, the lead author of a study that appears in the journal As the global average temperature rises, forests and woodlands around the world are under increasing threat, she explained."It's not just about temperature and rainfall, but also the organisms the trees and plants associate with," she said. Soil fungi have a variety of relationships with woodland plants. Saprotrophic fungi, for instance, decompose dead organic matter, while pathotrophs eat live organic matter.And then there are the symbiotrophs, which engage in mutually beneficial relationships with their plant hosts via their roots. Attaching to roots and extending threadlike hyphae in every direction underground -- the so-called "Wood Wide Web" -- mycorrhizae give the woodland tree and plant community access to nutrients from faraway places."They get all of their energy in an exchange for carbon from trees and other plants," Bui said. "And then they give their hosts nitrogen and phosphorus from the soil." These fungi provide almost half of a tree's organic nitrogen budget, according to the study, and contribute the bulk of new carbon into the soil.To get a sense of how warming could affect California's woodland soil fungal community, the team sampled soils at sites along an arid (dry) to mesic (moderately moist) climactic gradient at the Tejon Ranch in the Tehachapi mountains."The sites we worked at were a proxy for what we think California would look like with future climate change," Bui said. As one ascends from the warmer, drier base of the mountains into the cooler, moister elevations, the landscape changes with the temperature and relative humidity, giving the researchers a glimpse of what California woodlands might look like as climate change forces them to retract.Of particular interest to the team were the soils around the oak trees that dot the landscape, where, in addition to the decomposers and pathogenic fungi in the soil, tree-mutualist mycorrhizae create their vast networks. The researchers were interested in how the number of species and their abundance might change between sites."As it turns out, the fungal communities are completely different," Bui said. "And the hottest, driest sites have the highest number and the greatest diversity in fungal species." True to the Anna Karenina hypothesis, the trees under the more arid, stressful conditions had the most diverse and dispersed fungal communities.But, while the larger fungal communities varied from site to site, Bui said, the communities of mutualists within them tended to remain the same, save for small shifts within the mutualist populations to select for traits that could be more useful under the the circumstances."When we looked at ectomycorrhizae and arbuscular mycorrhizae, those communities were more similar across climactic conditions than the whole fungal community," she said. "So there's a possibility that host association for mutualists at least buffers that shift in community structure the whole fungal community experiences."If so, the benefit could be reciprocal, according to the researchers. Buffering the fungi from climate change preserves their function, which could, in turn, conserve their host trees' function in the face of a changing California woodland ecosystem.More work would need to be done to understand how far this buffering effect would extend, but the results are a positive bit of news for the future of California woodlands. Further studies could broaden the scope to include how these relationships and other adaptations might affect tree health, according to Bui."I think this gives us a little bit of hope that the players in this ecosystem that are crucial for the survival of the habitat for many species -- like the oaks -- might be able to keep doing what they're doing," she said. "Even though we do need to do a lot of work in terms of conservation and mitigation, there's a possibility for them to persist. And I think that's hopeful and exciting."Research in this paper was conducted also by Devyn Orr, Michelle Lepori-Bui, Kelli Konicek, Hillary S. Young and Holly V. Moeller, all at UC Santa Barbara. | Climate | 2,020 |
December 9, 2020 | https://www.sciencedaily.com/releases/2020/12/201209170638.htm | New study helps pinpoint when Earth's plate subduction began | A new study from scientists at Scripps Institution of Oceanography at UC San Diego and the University of Chicago sheds light on a hotly contested debate in Earth sciences: when did plate subduction begin? | According to findings published Dec. 9 in the journal For geochemists like Scripps assistant professor and study lead author Sarah Aarons, the clues to Earth's earliest habitability lie in the elements that ancient rocks are composed of -- specifically titanium. Aarons analyzed samples of Earth's oldest-known rocks from the Acasta Gneiss Complex in the Canadian tundra -- an outcrop of gneisses 4.02 billion years old. These rocks are dated from the Hadean eon, which started at the beginning of Earth's formation and was defined by hellish conditions on a planet that would look alien to our modern eyes.Aarons' research focused on isotopes, which are variations of the same element based on the number of neutrons they have. Taking the samples from Acasta Gneiss provided by Jesse Reimink, an assistant professor at Penn State University, she crushed bits of the rock into a powder that was then heated to form a glass bead, a process that allows dissolution of the titanium she sought to analyze. Once cooled, the bead was dissolved in acid and the titanium was chemically separated from other elements. Aarons was then able to determine the variations of titanium isotopes present in the sample using a mass spectrometer in the Origins lab led by her collaborator Nicolas Dauphas at the University of Chicago.Aarons compared these samples to newer, modern rocks formed in subduction zones. In samples aged at 3.75 billion years old, she noticed similarities in structure and composition to the modern ones, suggesting that plate subduction began around that time."A lot of previous work has been done on these rocks to carefully date them, and provide the geochemical and petrological context," said Aarons. "We were very lucky to get the opportunity to measure titanium isotope compositions, a burgeoning isotope system in these samples."Studying the history and onset of ancient subduction zones is notoriously difficult. Rocks are constantly destroyed as the crust is driven inward into the mantle, leaving behind few samples that date back into Earth's earliest history. Scientists have long debated when plate tectonics and subduction began, with estimates ranging from 0.85 to 4.2 billion years ago -- more than two-thirds of the planet's history. Discovering when plate subduction began means pinpointing when Earth transitioned from a planet dominated by transient landmasses piercing through the oceans' surface to one composed of long-lived continents where long-term biogeochemical cycles are controlled by volcanic degassing and recycling into Earth's interior.Plate subduction occurs when oceanic crust and continental crust collide. Because continental crust is thicker and less dense, oceanic crust is pushed downward into the Earth's mantle, at an average rate of a few centimeters each year. This contact with the mantle creates areas that are hot enough for magma to escape to the surface, creating volcanoes such as Mount St. Helens and others found along the Pacific Rim.Plate tectonics and subduction zones are responsible for the way Earth looks, driving the creation of continental plates and the basins that would fill to become oceans. They are also the primary control on the chemical characteristics of the planet's surface, and are likely responsible for Earth's ability to sustain life. These tectonic zones are responsible for the formation of emerged continents and provide an important control on climate by regulating the amounts of the greenhouse carbon dioxide in the atmosphere.In four-billion-year-old rock samples, Aarons saw similarities to modern rocks that are formed in plume settings, like Hawaii and Iceland, where a landmass is drifting over a hot spot. However, in rocks aged at 3.75 billion years, she noticed a shift in trend to rocks that are formed in modern subduction zones, suggesting that around that time in Earth's history these areas began forming."While the trend in the titanium isotope data does not provide evidence that plate tectonics was happening globally, it does indicate the presence of wet magmatism, which supports subduction at this time," said Aarons.The technique used in this study could be applied to other ancient rock formations around the world to gain more information about the composition and evolution of Earth's emerged lands through time.Other institutions involved in the study were Pennsylvania State University (USA) and the University of Bern (Switzerland). The study was funded by the National Science Foundation, NASA, the Ford Foundation Postdoctoral Fellowship, and the Swiss National Science Foundation. | Climate | 2,020 |
December 9, 2020 | https://www.sciencedaily.com/releases/2020/12/201209140346.htm | Temporal crop diversity stabilizes agricultural production | Securing food supplies around the globe is a major challenge facing humanity, especially in light of the predicted increase in the world's population to almost ten billion people by 2050 and the effects of climate change. Greater crop diversity in agriculture is seen as a stabilising factor for food security. Yet crop diversity alone is not sufficient. In an article for | Crop diversity is a key factor in securing agricultural production. Having a wider variety of crops reduces the risk of total harvest failure when certain crops are affected by plant diseases and protects against poor harvests resulting from extreme weather events, such as droughts, or pest infestation. "However, asynchrony is at least equally important in securing production," says Lukas Egli, UFZ agroecologist and first author of the study. Differences in the temporal sequence in which crops are sown and harvested on arable land or the variation in phenology, i.e. differing development over time during the vegetation period, are both examples of factors that lead to greater asynchrony. "The more heterogeneously crops are distributed in time and respond to the effects of extreme events, natural disasters and economic crises, the less the agricultural production of a country as a whole will fluctuate," says Egli. For example, when different types of crops become ready to harvest at the same time this increases the likelihood of the entire harvest being destroyed in a storm or flood. Asynchrony prevents such total failure, for instance by varying sowing and harvesting times, growing crops with different climate and cultivation requirements and mixed cropping.The analysis of data from the Food and Agriculture Organization (FAO) revealed that India, Mexico and China are among the countries with a high level of production stability and asynchrony, whereas Russia, Australia and Argentina have a low level of stability and asynchrony. At present, one observes that asynchrony in agriculture is decreasing at the global level. "Globalised agricultural markets allow crop failures in one region to be compensated by trade with other regions. Trade itself is therefore a stabilising factor and could make the cultivation of a wide variety of crops with different growth patterns seem less important," says Prof Dr Ralf Seppelt, UFZ landscape ecologist and co-author. Nevertheless, countries should give greater consideration to highly diversified and asynchronous crops than they have done in the past to make food production less vulnerable to the uncertainties of the global market. | Climate | 2,020 |
December 9, 2020 | https://www.sciencedaily.com/releases/2020/12/201209124917.htm | Warmer springs mean more offspring for prothonotary warblers | Climate change contributes to gradually warming Aprils in southern Illinois, and at least one migratory bird species, the prothonotary warbler, is taking advantage of the heat. A new study analyzing 20 years of data found that the warblers start their egg-laying in southern Illinois significantly earlier in warmer springs. This increases the chances that the birds can raise two broods of offspring during the nesting season, researchers found. | They report their findings in the journal "Warmer springs in temperate regions of the planet can create a mismatch between when food is available to breeding birds and when their energy demands are highest -- when they are feeding nestlings," said Illinois Natural History Survey avian ecologist Jeffrey Hoover, who conducted the study with INHS principal scientist Wendy Schelsky. If climate change diminishes insect populations at critical moments in the birds' nesting season, food shortages may cause some chicks and even adults to die. Other long-distance migratory birds suffer ill consequences from warmer springs on their breeding grounds.But this mismatch seems not to occur in prothonotary warblers, the researchers found.In the Cache River watershed, where the study was conducted, the warblers nest in swamps and forested wetlands, which are abundant sources of insects throughout the spring and summer. The warblers eat caterpillars, flies, midges, spiders, mayflies and dragonflies. As long as it does not dry up, the wetland habitat provides a steady supply of food to sustain the birds."We studied populations of prothonotary warblers nesting in nest boxes in these areas from 1994-2013," Schelsky said. The researchers captured and color-banded the birds, studying 2,017 nesting female warblers in all. They visited the nests every three to five days from mid-April to early August, keeping track of when each bird laid its first egg and the birds' overall reproductive output for each nesting season.They also compared local April temperature trends with those of the Annual Global Land Temperature Anomaly data, a federal record compiled by the National Oceanic and Atmospheric Administration. They found that local conditions reflected global temperature changes.When local temperatures were warmer in April, the birds tended to lay their first eggs earlier in the spring and, on average, produced a greater number of offspring over the course of the breeding season."It was exciting to see that the birds could be flexible and adjust their timing of breeding to be earlier in warmer years and benefit by doing so," Schelsky said. Starting earlier meant more of the birds could raise additional broods of offspring.As the warming trend continues, conditions may change in ways that harm the birds' reproductive capacity, Hoover said."Even though these warblers currently produce more offspring in warmer years, continued global warming may eventually upset the balance between arrival dates, food resources and the commencement of nesting," he said. For example, warmer temperatures could cause local wetlands to dry up during the nesting season, cutting off the steady supply of insects the birds rely on to raise their young and increasing the exposure of nests to predators. | Climate | 2,020 |
December 9, 2020 | https://www.sciencedaily.com/releases/2020/12/201209115205.htm | Index reveals integrity issues for many of the world's forests | Only 40 per cent of forests are considered to have high ecological integrity, according to a new global measure, the Forest Landscape Integrity Index. | The Index was created by 47 forest and conservation experts from across the world, including Professor James Watson of The University of Queensland and the Wildlife Conservation Society."This extremely fine-scale analysis of the ecological integrity of the world's forests has found that only 17.4 million square kilometres of Earth's remaining forests -- or 40 per cent of them -- are considered to have high integrity," Professor Watson said."And just 27 per cent of this area is found in nationally designated protected areas."High integrity forests are those which contain high levels of biodiversity, provide high quality ecosystem services and are more resilient to climate change."Many of our remaining forests have been heavily impacted by a variety of human activities, including logging, fires, hunting, wildlife exploitation and edge effects."These actions damage forest integrity."By protecting and expanding forests with high integrity, we can help slow the impacts of climate change, preserve biodiversity, protect the rights of indigenous peoples and local communities and prevent future pandemics."Professor Watson said the index was a result of rapid advances in remote sensing, big data and cloud computing."The use of this index is critical in allowing us to locate Earth's remaining intact forests and ensure that they are better protected but also hold nations to account for how they treat their forests," he said."We show how critical some countries are, including Canada, Brazil, Democratic Republic of Congo, Papua New Guinea and Australia, in sustaining the world's last large intact forests."The fine-scale nature of the map will also allow land managers to plan activities more effectively and to monitor change over time."Dr Hedley Grantham, lead author of the study and WCS's Director of Conservation Planning, said the study's results were fundamental to talks at the Convention on Biological Diversity."The current draft of the post-2020 Global Biodiversity Framework wisely proposes targets relating to ecosystem integrity and there has been active discussion about how this can be quantified and monitored," Dr Grantham said."Using this index, we can now set ambitious policy goals to improve the integrity of forests globally." | Climate | 2,020 |
December 9, 2020 | https://www.sciencedaily.com/releases/2020/12/201209094229.htm | Southern Hemisphere westerly winds likely to intensify as climate warms | Polar climate scientists have created the most high resolution past record of the Southern Hemisphere westerly winds. The results, published this week (9 December) in the journal | The westerly winds (known by latitude as the roaring forties, furious fifties, and screaming sixties) are particularly strong due to the absence of continental landmasses in the Southern Ocean to slow them down. They play an important role in regulating how much carbon dioxide (greenhouse gas) is exchanged between the atmosphere and ocean and have been linked to droughts and wildfires, as well as changes in sea ice extent, ocean circulation and ice shelf stability.Researchers have recreated a 700-year record of the winds using radiocarbon dated sediment cores collected from a coastal lake on sub-Antarctic Marion Island. The island, located southeast of South Africa, is uniquely positioned in the core belt of the winds. The team measured changes in the accumulation rate of wind-blown sea salts by studying diatoms -- tiny algae, specifically microalgae -- embedded in the sediment, together with wind-blown dust, to track past wind strength.Results show that during cool periods, such as the Little Ice Age (c. 1400-1870 CE), the winds weakened and shifted towards the equator, and during warm periods (before 1450 and after 1920) they intensified and migrated poleward.Lead author, Dr Bianca Perren, a paleoclimatologist at British Antarctic Survey says:"From this unique high resolution record we can see how much the westerly winds have changed over the last 700 years. By looking at the past we can better understand what's happening now and what might happen in the future. It's clear that since the 1920s the winds have been migrating south and, with predictions for climate warming, this is likely to continue."The project Principal Investigator, Professor Dominic Hodgson at British Antarctic Survey says:"With the rapid changes now occurring in the Earth's climate it is especially important that we use historical data to increase the accuracy of our climate models. This study has revealed the behaviour of the westerly winds long before satellites and on the ground measurements began. It shows us that climate warming drives moisture bearing winds southwards away from Australia, South America and South Africa. The immediate human consequences of this are increased droughts and wildfires." | Climate | 2,020 |
December 8, 2020 | https://www.sciencedaily.com/releases/2020/12/201208153730.htm | Wildfire risk rising as scientists determine which conditions beget blazes | As wildfires burn more often across the Western United States, researchers at the U.S. Department of Energy's Pacific Northwest National Laboratory are working to understand how extensively blazes burn. Their investigation, aided by machine learning techniques that sort fires by the conditions that precede them, not only reveals that the risk of wildfire is rising, but also spells out the role moisture plays in estimating fire risk. | In findings shared virtually at the American Geophysical Union's 2020 fall meeting on Tuesday, Dec. 1, atmospheric scientists Ruby Leung and Xiaodong Chen detailed their study of decades-long wildfire records and new simulations of past climate conditions, which they used to identify variables that lead to wildfires. The two will answer questions virtually on Tuesday, Dec. 8.Surprisingly, just enough humidity in the air -- not enough to lead to precipitation -- can boost the likelihood of lightning, which can ignite dry grasslands or water-starved trees. The CZU Lightning Complex fires in Santa Cruz, Calif., for example, were triggered by lightning on Sunday, Aug. 16, 2020, and burned nearly 1,500 structures.While scientists have known the importance of such hydro-meteorological conditions, generating enough data to tease out lengthy soil moisture or humidity trends and thoroughly representing their influence is only recently possible through computational advances in modeling, according to Leung.The researchers employed machine learning to classify wildfires into "types," producing categories like fires that strike when soil is damp or during cloudy days, and the most quickly rising type -- fires that spark on warm, dry, sunny days.These "compound case" wildfires, named for their multiple contributing factors, strike more frequently than any other. A warming climate, said Leung, is likely to exacerbate the trend."Based on the historical trends we see over the past 35 years," said Leung, "it is very likely that trend will continue. That is partly driven by rising temperature and partly driven by reduced soil moisture as snowmelt starts earlier in spring, reducing soil moisture in summer and fall."This study marks progress toward building a more comprehensive, data-rich take on the hydroclimatic priming of wildfires. Such detailed simulations like the one Leung and Chen incorporated in their study offer a more fine-grained glimpse into how wildfires evolve."This allows us to draw a very complete picture of how wildfire is triggered across the whole Western United States," said Chen.Nearly all types of wildfire, including cloudy day fires, are happening more often. "Wet case" fires, which occur when soil moisture levels are higher, are the exception, and their decline coincides with an overall drying trend in the Western United States. California's wet season window is also narrowing, said Leung, adding another challenge to an already fire-ravaged state.The team plans to project wildfire risk into 2070, demonstrating how that risk shifts under different climate scenarios, and to investigate the role snowpack and precipitation seasonality play in wildfire. This work was carried out under the DOE's HyperFACETS project. This and similar work will inform many research and applications communities and lead to better prediction and preparations for future wildfire seasons.One aspect of that new work will focus on a single catastrophic event, the 2017 wildfire season in the Western United States, for example, and tweaking conditions to create analogs of likely future events. Whether in fundamental research in landscape evolution and disturbances, or in land, water and wildfire management and resource planning, said Leung, this approach allows for the generation of an assortment of relevant scenarios with accompanying details.The research was funded by the DOE Office of Science. | Climate | 2,020 |
December 8, 2020 | https://www.sciencedaily.com/releases/2020/12/201208121052.htm | Coral recovery during a prolonged heatwave offers new hope | University of Victoria biologists have discovered how some corals managed to survive a globally unprecedented heatwave, in a first-ever study that provides new hope for the long-term survival of coral reefs in the face of climate change. | "The devastating effects of climate change on coral reefs are well known. Finding ways to boost coral survival through marine heatwaves is crucial if coral reefs are to endure the coming decades of climate change," says UVic marine biologist Julia Baum, the study's senior author.Published today in Worldwide, coral reef fisheries are worth US$6.8 billion annually, and are a vital source of food and income for hundreds of millions of people in tropical island nations. In the lead-up to the United Nations Decade of Ocean Science for Sustainable Development (2021-2030), there is a renewed and global call to reverse the cycle of decline in ocean health."Understanding how some corals can survive prolonged heatwaves could provide an opportunity to mitigate the impact of marine heatwaves on coral reefs, allowing us to buy time as we work to limit greenhouse gas emissions," says Danielle Claar, who led the study as a UVic doctoral student and is now a postdoctoral researcher at the University of Washington.Climate change threatens the world's coral reefs because corals are highly sensitive to the temperature of their surrounding waters. During a heatwave, corals release the algae that live in their tissues and produce food for them, causing the coral to turn completely white -- a phenomenon known as coral bleaching. Prolonged bleaching often causes corals to die from starvation. If they can reclaim their food source within a few weeks, they can usually recover.To date, coral recovery from bleaching has only ever been observed after heat stress subsides. With global climate models predicting that heatwaves will continue to increase in both frequency and duration, a coral's ability to recover its food source during a prolonged heatwave is essential to its survival."Observing corals recovering from bleaching while still baking in hot waters is a game changer," says Baum.Baum adds that corals only exhibited this capacity if they were not also exposed to other types of human-caused stressors, such as water pollution. Until now it's been unclear if local reef management could help improve corals chances of surviving climate change. "We've found a glimmer of hope that protection from local stressors can help corals," says Baum."Although this pathway to survival may not be open to all corals or in all conditions, it demonstrates an innovative strategy for survival that could be leveraged by conservationists to support coral survival," adds Claar.The research was supported by the Natural Sciences and Engineering Research Council of Canada, the US National Science Foundation, the David and Lucile Packard Foundation, Pew Fellowship, the Rufford Foundation, the Canadian Foundation for Innovation and the Shedd Aquarium. | Climate | 2,020 |
December 8, 2020 | https://www.sciencedaily.com/releases/2020/12/201208111634.htm | Climate change exacerbates biodiversity loss | A considerable number of existing and proposed post-2020 biodiversity targets by international organizations are at risk of being severely compromised due to climate change, even if other barriers such as habitat exploitation are removed argue the authors of a study led by Almut Arneth from Karlsruhe Institute of Technology (KIT). According to their analysis published in | About a million plant and animal species are endangered worldwide. At least 13 of the 17 sustainable development goals of the United Nations, however, depend on biodiversity, including species diversity, the genetic diversity within species and the diversity of ecosystems. Biodiversity regulates fundamental processes, such as soil formation and water-, trace-gas-, and nutrient cycles and thus contributes notably l to regulating the climate. The continued loss of biodiversity makes humankind face ecological, social, and economic problems. "Apart from the over-exploitation of natural resources on land and in water, or environmental pollution, climate change also causes loss of biological diversity. This impact will increase in future," says Almut Arneth, Professor at the Atmospheric Environmental Research Division of the Institute of Meteorology and Climate Research (IMK-IFU), KIT's Campus Alpine in Garmisch-Partenkirchen. She led an international study that is now published in the In their study, scientists from Germany, France, Italy, Spain, Russia, South Africa, Mexico, and Japan analyzed the so-called Aichi targets for the worldwide protection of biodiversity that were adopted by the 10th Conference of the Parties of the UN Convention on Biodiversity in Nagoya, prefecture of Aichi, in 2010 for compliance by 2020. Most of these targets will be missed. In addition, the researchers analyzed the set of revised biodiversity protection targets currently negotiated by the parties for the time after 2020, which are to be reached by 2030 or 2050. They found that many existing or proposed targets are at risk due to global warming, even if the mean global temperature increase would remain at the lower limit of projections. "It certainly is a big challenge, but also an important opportunity to better handle on the political level the interactions between climate change and biodiversity loss, and to better coordinate the biodiversity targets with the Paris Agreement on Climate Change and the Sustainable Development Goals," Arneth explains. The biodiversity targets proposed should therefore consider climate change much more explicitly, she thinks.Arneth gives an example: A biodiversity target for nature reserves must consider the fact that composition and growth of vegetation will change with climate change and that certain species of plants and animals will either migrate or be threatened, if climatic conditions are changing. For instance, climate change causes mountain glaciers to shrink. In semi-arid regions, however, lower lying valley ecosystems depend on melting water from glaciers in summer. If this melt-water flow will decrease due to retreating glaciers, precipitation alone may not be sufficient to supply the plants in the catchment with water. This will then also affect the animals that are dependent on the plants.The study underscores the demand to quickly and significantly reduce anthropogenic greenhouse gas emission and to halt climate change. Vice versa, it also shows that measures to protect biodiversity would contribute to climate protection. "Better coordination of political agreements and scientific findings may accelerate urgent decarbonization of economy and ensure slowdown of climate change by biodiversity protection measures," Arneth summarizes. | Climate | 2,020 |
December 8, 2020 | https://www.sciencedaily.com/releases/2020/12/201208111432.htm | New study allows regional prediction of uranium in groundwater | Lurking in sediments and surrounding the precious groundwater beneath our feet is a dangerous toxin: uranium. Scientists have long known this and tested for it. But now Stanford researchers have identified the trigger that causes naturally occurring uranium to dislodge from sediments and seep into groundwater, pointing to a solution for managing the toxin before it becomes a problem. | In a new regional model that combines aquifer information with soil properties for predicting groundwater quality, the researchers pinpointed the factors associated with uranium contamination. The research, published in Uranium is among the top three harmful, naturally occurring groundwater contaminants in the Central Valley, along with arsenic and chromium. The radioactive, metallic element becomes dangerous when consumed in high quantities, causing kidney damage and increased risk of cancer. It is prevalent within the Central Valley's San Joaquin Valley, and also occurs naturally in semi-arid and arid environments worldwide.Researchers focused on locations in the Central Valley aquifers where groundwater uranium concentrations have been observed to exceed the drinking water standard of 30 micrograms of uranium per liter."Every aquifer has one or more of these natural contaminants. The question is whether they sit benignly in the sediments or really cause problems by getting into the groundwater," said co-author Scott Fendorf, the Huffington Family Professor in Earth system science at the School of Earth, Energy & Environmental Sciences (Stanford Earth). "Water managers can use our findings to forecast solutions before the problems are manifested."The study focuses on the chemical impacts of groundwater recharge, which is the process of rainfall seeping into soils and moving down into underlying aquifers. As rainwater seeps downward, its chemistry changes as it interacts with the ground environment. Pumping the water back out also influences the dynamics of the aquifer, which can change the chemistry of the system and how elements such as uranium are partitioned between the solids (sediments) and water. If the water picks up more calcium during its travels and also becomes more alkaline, it can attract uranium and contaminate aquifers, the researchers found."Our work shows that it's not just properties of the aquifer that are impacting uranium, but factors such as clay content and pH of the soil that served as important predictors of groundwater uranium concentrations," said lead study author Alandra Lopez, a PhD student in Earth system science. "It highlights the importance of including data about soil properties when generating aquifer vulnerability maps for a naturally occurring contaminant like uranium."The good news: the researchers estimate that the factors introducing this process of uranium loosening from sediments into groundwater mainly occur within the top six feet of the soil, suggesting an easy fix could involve bypassing that area."If you're going to manage aquifer recharge, which will be increasingly needed with climate change, be careful about having the water infiltrate through the soil where calcium and alkalinity are often highest. These management scenarios are being considered right now," said Fendorf, who is also a senior fellow at the Stanford Woods Institute for the Environment.The team says their methodology offers water managers an easy way to predict major influences on groundwater uranium concentrations at scale."We're trying to tell everybody that you need to think about this ahead of time, because that's when you can manage around the problem," Fendorf said. "It's a kind of forward prediction versus hindsight reaction -- once you measure uranium in the water, your problem is already at hand and it's much more expensive to fix."This research was funded by the Water Foundation, a US National Science Foundation Graduate Research Fellowship and partly supported by the US Department of Energy, Office of Biological and Environmental Research, Subsurface Biogeochemistry Program (SBR). | Climate | 2,020 |
December 8, 2020 | https://www.sciencedaily.com/releases/2020/12/201208090004.htm | Beavers may help amphibians threatened by climate change | The recovery of beavers may have beneficial consequences for amphibians because beaver dams can create the unique habitats that amphibians need. | That finding was reported by four WSU Vancouver scientists in a paper published in the journal Certain types of amphibians, particularly those that develop more slowly, such as red-legged frogs and northwestern salamanders, were detected almost exclusively in dammed sites."Beaver-dammed wetlands support more of the amphibian species that need a long time to develop in water as larvae before they are able to live on land as adults," said Jonah Piovia-Scott, assistant professor in the School of Biological Sciences and one of the authors of the article.Beavers, once abundant in the Pacific Northwest, were hunted nearly to extinction in the 19th century. But, in an effort to improve wildlife habitat and mitigate the effects of climate extremes, some land managers are relocating beavers into places they occupied in the past, and beavers' numbers are slowly recovering, which is also benefiting amphibians, according to the study.Red-legged frogs and northwestern salamanders are also the species most threatened by climate change, which is projected to bring drier summer conditions to streams and wetlands in the Cascade Range. By expanding existing ponds and increasing the time before they dry up, beaver dams are allowing such species more time to reproduce and develop."Beavers may be a key component of ecological resilience to climate change in these ecosystems," Piovia-Scott said.In addition to Piovia-Scott, the authors of the study are Kevan Moffett, assistant professor in the School of the Environment; John Romansic, former postdoctoral scholar in the School of Biological Sciences; and Nicolette Nelson, former graduate student in the School of Biological Sciences. | Climate | 2,020 |
December 7, 2020 | https://www.sciencedaily.com/releases/2020/12/201207195140.htm | Hard and fast emission cuts slow warming in the next 20 years | A new study shows that strong and rapid action to cut emissions of carbon dioxide and other greenhouse gases will help to slow down the rate of global warming over the next twenty years. | This highlights that immediate action on climate change can bring benefits within current lifetimes, and not just far into the future.Scientists already agree that rapid and deep emissions reductions made now will limit the rise in global temperatures during the second half of the century.However, pinpointing shorter-term benefits over the next few decades has been more challenging, particularly as natural cycles in global atmosphere and ocean systems can cause slow ups and downs in temperature that temporarily mask human influence on the climate.But, by using a novel approach that combines large amounts of data from different sources, a new study from the University of Leeds has untangled human-induced warming from natural variability on much shorter timescales than previously thought possible.The study, published in The findings show that reducing emissions in line with the Paris Agreement, and in particular with its aim to pursue efforts to stabilise global warming at 1.5°C above pre-industrial levels, has a substantial effect on warming rates over the next 20 years, even after natural variability is taken into account.In fact, the risk of experiencing warming rates that are stronger than anything previously seen would be 13 times lower with rapid and deep emissions cuts, compared to an "average" future that continues to rely heavily on fossil fuels. A fossil-fuel heavy future could see temperatures rise by up to 1-1.5°C in the next 20 years -- meaning the Paris Agreement temperature limits will be breached well before 2050.The study's lead author, Dr Christine McKenna, is a Postdoctoral Research Fellow at Leeds's School of Earth and Environment, working on the EU-funded CONSTRAIN-project.Dr McKenna said: "Our results show that it's not only future generations that will feel the benefits of rapid and deep cuts in emissions. Taking action now means we can prevent global warming from accelerating in the next few decades, as well as get closer to the goal of limiting warming in the longer term."It will also help us to avoid the impacts that more rapid and extreme temperature changes could bring."With global temperatures currently rising at around 0.2 °C per decade, without urgent action on climate change we are clearly in danger of breaching the Paris Agreement. These findings are further motivation for both governments and non-state actors to set stringent greenhouse gas mitigation targets, combining a green recovery from the economic impacts of coronavirus with reaching net-zero emissions as soon as possible." | Climate | 2,020 |
December 7, 2020 | https://www.sciencedaily.com/releases/2020/12/201207131301.htm | Marine ecosystems: No refuge from the heat | Over the past several decades, marine protected areas (MPAs) have emerged as a favored conservation tool. By protecting marine species and safeguarding habitat, these reserves help buffer ecosystems against natural and human-made shocks alike. | Researchers at UC Santa Barbara and the National Oceanic and Atmospheric Administration (NOAA) sought to determine how well MPAs protect fish from changes caused by marine heatwaves. These stressful events can drastically alter an ecosystem, and scientists predict they will increase in frequency and intensity as the climate warms.To answer these questions, the team took advantage of a marine heatwave that affected the entire West Coast between 2014 and 2016, using 16 years of data from the Channel Islands. The archipelago lies at the transition between subtropical ecosystems in the south and temperate ecosystems north of Point Conception, and is dotted with a network of a dozen or so no-take reserves.According to the researchers' findings, published in the journal No-take marine protected areas are extremely useful strategies for marine conservation. Because they are a whole-ecosystem management tool, many scientists believe they can help mitigate climate shifts. Prior research has shown that MPAs can increase species' numbers, stabilize ecosystems and even increase fishery catches -- all effects that should, in theory, offer protection against climate change."There have been many studies showing that MPAs are effective at preserving biodiversity and facilitating recovery of single species during and after extreme temperature events," said lead author Ryan Freedman, a former doctoral student in the lab of Jennifer Caselle, a researcher at UCSB's Marine Science Institute. "Given these aspects, and the body of work on MPA benefits, a lot of resource managers point to MPAs as a way to mitigate climate effects even though there have been just a few studies on the topic."Fortunately, Freedman and his team had a wealth of data from around the Channel Islands thanks to PISCO, the Partnership for Interdisciplinary Studies of Coastal Oceans. The academic consortium conducts research on California's coastal ocean to inform management and policy. PISCO has datasets stretching back to 1999, as well as monitoring sites inside and outside the islands' MPAs.Freedman made use of a marine heatwave that affected the region in 2014 as a sort of natural experiment. He compared fish density, biomass, biodiversity and the recruitment of juveniles between warm-water and cold-water species to investigate how the marine protected areas mediated the impact of the heatwave."We found that the heatwave had an outsized effect on density, recruitment and biodiversity compared to typical oceanographic events like El Niño," Freedman said. "Once we saw that, we focused on data just during the heatwave years to look closely at the trends inside and outside MPAs."The team asked if fish communities inside the reserves remained similar before, during and after the heatwave in comparison to unprotected locations. Instead, they found little difference in the way that fish communities shifted inside and outside the MPAs.The researchers were surprised by the results, but have formulated a possible explanation. They suspect that trends were similar within and without the MPAs because the heatwave tended to affect non-fished species -- like rock wrasses and Garibaldi -- more than those targeted by fisheries. For non-targeted species, the additional protection of a no-take marine reserve is a moot distinction when it comes to marine heatwaves."We suspect [non-]targeted species are more responsive because they are usually smaller and have shorter life histories than targeted species," Freedman explained. As a result, non-fished species likely feel a stronger impact from acute events like marine heatwaves. Additionally, non-targeted species are generally more abundant, which means there are more individuals for a heatwave to effect.The implications of these findings seem pretty clear to Freedman. "Because MPAs alone can't mitigate acute ecosystem change during heatwaves, resource managers will need to use a suite of conservation options to maintain important ecosystem services in the Santa Barbara Channel and beyond as heatwaves become more common," he said.This study also highlights the close partnership between UC Santa Barbara and the NOAA Channel Islands National Marine Sanctuary, where Freedman was employed during his Ph.D. and where he is now a research ecologist."Strong partnerships between academic researchers and resource managers are critical to solving some of the most difficult environmental challenges," said Caselle. "Having the office of the Channel Islands National Marine Sanctuary physically located on our campus is a huge benefit to researchers working on applied problems and managers looking for scientific solutions."This is the first in a series of papers that aims to identify some of the ways an altered climate will impact the future of kelp forests in Southern and Central California. The team recently submitted another manuscript outlining how they classified warm-water and cold-water species in the hopes that other conservation groups can use their methodology to improve the accuracy their own work. The final paper in the series forecasts future changes in fish species under different climate scenarios for the Santa Barbara Channel, with a goal of allowing for proactive management in the face of climate change. | Climate | 2,020 |
December 7, 2020 | https://www.sciencedaily.com/releases/2020/12/201207124124.htm | New geological findings from eastern Fennoscandia add new dimensions to the history of European ice | In Finland, the majority of the glacial and warm interval records have been interpreted to represent only the last, Weichselian, glacial cycle that took place 11,700-119,000 years ago. Finnish researchers have now revised the crucial part of the existing stratigraphic documentation in southern Finland. The new findings show that a considerable part of the warm interval records extends further back in time than earlier thought. The new results change the established conceptions about glacial history in the area. | The new study conducted at the University of Turku has examined geological stratigraphic sequences in southern and central Finland. The material collected during the study was compared with corresponding stratigraphic sequences in Fennoscandia, the Baltic countries and Europe.- One of the studied warm interval records may be circa 300,000-400,000 years old. The forests in South Finland were then composed of scots pine and Norway spruce and contained larch, fir and possibly some species related to present-day Strobus pine, says Professor of Geology Matti E. Räsänen.A major part of the revised warm interval records is, however, attributed to the Röpersdorf-Schöningen interglacial circa 200,000 years ago. The study led by Räsänen has, for the first time, managed to reconstruct the paleogeography, vegetation and climate of this regional interglacial in Fennoscandia. During this interglacial period, the ocean levels were nearly 20m lower than today, and the Gulf of Bothnia hosted fresh water lakes surrounded by boreal pine forests.- This is why Finland had a continental climate with warmer summers and colder winters than today. The forests were dominated by scots pine and the Siberian spruce was growing even in southern Finland. Several species that nowadays grow on the East European Plain and in Southeast Europe were growing in southern Finland, explains Räsänen.During the Eemian interglacial 119,000-131,000 years ago, ocean levels were four to six metres higher than today and the Baltic basin was well connected to oceans.- The dinoflagellate, silicoflagellate and diatom microfossils discovered from the stratigraphic sequences show detailed evidence of the widespread intermixing of continental fresh and marine waters within the shallow Eemian sea coastal waters.Most importantly, the research results change the established conceptions about the nature of the temperate Brörup interval in the beginning of the last Weichselian glacial cycle circa 100,000 years ago. The findings from Björkö Island in the UNESCO World Heritage Site of Kvarken Archipelago suggest that during this interval, central and southern Finland supported open birch forest tundra, which was later invaded by spruce, but not boreal pine forests as earlier thought.- The northern limit of pine forests seems to have been located at the Gulf of Riga in the Balticum. The climate in southern Finland was thus considerably cooler than thought. These results are important as they provide background information for the modelling of future climate, concludes Räsänen. | Climate | 2,020 |
December 7, 2020 | https://www.sciencedaily.com/releases/2020/12/201207124106.htm | The natural 'Himalayan aerosol factory' can affect climate | Large amounts of new particles can form in the valleys of the Himalayas from naturally emitted gases and can be transported to high altitudes by the mountain winds and injected into the upper atmosphere. | The emitted particles may eventually affect climate by acting as nuclei for cloud condensation. These new findings about particles formation and sources will contribute to a better understanding of past and future climate."To understand how the climate has changed over the last century we need to know as reliably as possible the natural atmospheric conditions before the industrialization," says Associate Professor Federico Bianchi from the University of Helsinki's Institute for Atmospheric and Earth System Research (INAR).In order to do that scientists are looking for pristine locations around the world where human influence is minimal. An international group of researchers has now completed a comprehensive study at the Nepal Climate Observatory at Pyramid station, located in the proximity of the Everest base camp at 5050 m above sea level. There, they were able to investigate the formation of atmospheric particles far from human activities. The results were published today in the journal The study shows that up-valley winds bring vapours emitted by vegetation at the Himalayan foothills to higher altitudes. During this transport, these gases are transformed by photochemical reactions into compounds of very low volatility, which rapidly form a large number of new aerosol particles. These are then transported into the free troposphere, a region of the atmosphere with very low human influence."You can think of the whole Himalayas as an 'aerosol factory' that continuously produces a large amount of particles and then directly injects them high up into the atmosphere above the Everest," says Bianchi. We calculate from these measurements that the transport of particles may increase present-day particle concentration above the Himalayas by a factor of up to two or more.It's the first time the scientists consider mountain venting as a big potential source of atmospheric particles in the free troposphere.Additionally, the freshly formed particles have natural origin with little evidence of the involvement of anthropogenic pollutants. This process is therefore likely to be essentially unchanged since the pre-industrial period, and may have been one of the major sources contributing to the upper atmosphere aerosol population during that time. These new observations are therefore important to better estimate the pre-industrial baseline of aerosol concentrations in this large region. The inclusion of such processes in climate models may improve the understanding of climate change and predictions of future climate.Future studies shall focus on a better quantification of this phenomenon and investigate it also in other high mountain regions. | Climate | 2,020 |
December 7, 2020 | https://www.sciencedaily.com/releases/2020/12/201207112316.htm | Central Europe: Dry Aprils pave the way for summer droughts | In the past 20 years, Central Europe has experienced six summer heat waves and droughts. Until now, however, it was unclear what factors led to these extreme events. Researchers from two Helmholtz Centres (AWI & UFZ) have now discovered that in Central Europe, temperature and precipitation patterns in April play a vital role in determining whether or not the soils are drier than average in the following summer. If the April is too warm, with little precipitation, a large proportion of the moisture stored in the soil evaporates, making a summer drought more likely. The team has also identified one of the reasons for the repeated dry Aprils and the correspondingly increased risk of drought. Decreasing temperature differences between the Arctic and the middle latitudes lead to a shift in the jet stream and the formation of a blocking high-pressure system over the North Sea and parts of Germany. This in turn means that the April weather in Central Europe is getting much too warm and dry, as the researchers report in a study released today in the Nature Partner Journals | Monica Ionita, a climatologist and expert on weather forecasting at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), can still remember it clearly: in late April 2018, it was so hot in Bremen that she put a paddling pool in the garden for her daughter, although it should have been much too early to splash around outdoors. She now knows that the spring heat wave at the time provided the impetus for the following summer being one of the driest in the history of Central Europe."Since the turn of the century, Central Europe has experienced repeated summer heat waves and droughts, which have caused damage amounting to millions of Euros. To date, attempts to correctly predict such extreme events have been unsuccessful because the influence of the spring has been underestimated. That is why we decided to closely investigate the links between the weather in spring and that in the subsequent summer -- for the entire period for which sufficient records are available. In other words, the last 140 years," the expert reports.For the analysis, Monica Ionita and her colleagues employed climate (and hydrologic) model outputs as well as statistical methods that the AWI researchers have developed; and had already successfully applied in long-term forecasts of river water levels. The findings show: in the last 14 years, the temperature and precipitation trends in April have changed fundamentally. "While there was little change in the months of March and May in the period 2007 to 2020, April was on average 3 degrees Celsius warmer compared to the reference period 1961 to 2000. In extreme years, like 2018, it was so warm in April that the snow that had fallen in winter virtually evaporated before it had the chance to drain into the soil in the form of meltwater. Furthermore, since 2007, in most regions of Central Europe there has only been half as much rain as in the reference period," Ionita explains.In the past 14 years, the absence of precipitation has only been one of the problems: "Rising April temperatures have led to the moisture stored in the soil evaporating. As a result, in spring there was already a marked lack of moisture in the soils of Central Europe, especially in Germany. As a rule, this deficit couldn't be compensated for in the summer. In other words: the summer drought in the soils was pre-programmed back in April," adds Rohini Kumar, a hydrologist at the Helmholtz Centre for Environmental Research (UFZ) in Leipzig and co-author of the new study.But which weather conditions over Central Europe cause the repeated record-high temperatures and dry spells in April? "Our analysis shows that a blocking high-pressure system formed over the North Sea and parts of Germany in that period, and this diverted the jet stream northwards, resulting in spells of sunny and dry weather in Central Europe lasting up to two weeks," explains Ionita. There was also a phase with similarly low precipitation in April in the period from 1881 to 1895. But at the time it wasn't as warm, which meant that less moisture evaporated from the soil and there weren't the long-term effects that we're seeing today. "The serious consequences of these spring dry spells are largely due to the rising air temperatures," comments Ionita.We can't yet say whether blocking high-pressure systems will determine the April weather in Central Europe in the future, since the climate is subject to natural fluctuations. But in their study, the scientists were able to identify one important driver: "One reason for the formation of stable high-pressure areas is the decreasing temperature differences between the Arctic and the middle latitudes in spring. Under these conditions, the jet stream that controls the weather in Central Europe follows a zigzagging course, allowing the high-pressure system to settle over the North Sea," Ionita adds.According to climate scenarios, these initial conditions will also occur in the future. However, high-pressure systems will form less frequently (be less likely to form) if we succeed in achieving the Paris climate goals and limit global warming to 1.5 degrees Celsius by 2100. "If temperature increases exceed this goal, it is highly likely that such high-pressure areas will form. In Central Europe, the month of April will continue to be warmer and drier than it was 20-30 years ago, thus paving the way for large-scale water shortages and arid soils all summer long," warns the AWI researcher."Such a development would have major effects on the soils' water balance and their associated ecosystem services," states Kumar, adding: "In recent years, we've seen a series of summer droughts throughout Central Europe -- with severe consequences in terms of plant productivity and low water-levels in rivers. Understanding the conditions under which such dry periods occur is vital to implement precautionary and preventive measures in time." | Climate | 2,020 |
December 7, 2020 | https://www.sciencedaily.com/releases/2020/12/201207112304.htm | Peatland preservation vital to climate | Preserving the world's peatlands -- and the vast carbon stores they contain -- is vital to limiting climate change, researchers say. | The study, led by the University of Exeter and Texas A&M University, examines peatland losses over human history and predicts these will be "amplified" in the future.Peatlands are expected to shift from an overall "sink" (absorbing carbon) to a source this century, primarily due to human impacts across the tropics, and the study warns more than 100 billion tons of carbon could be released by 2100, although uncertainties remain large.Peatlands are currently excluded from the main Earth System Models used for climate change projections -- something the researchers say must be urgently addressed."Peatlands contain more carbon than all the world's forests and, like many forests, their future is uncertain," said Professor Angela Gallego-Sala, of Exeter's Global Systems Institute."Peatlands are vulnerable to climate change impacts such as increased risk of wildfires and droughts, the thawing of permafrost and rising sea levels."However, the main threats to peatlands are more direct -- particularly destruction by humans to create agricultural land."So the future of peatlands is very much in our hands."Peatlands are a type of wetland found in almost every country on Earth, currently covering 3% of the global land surface.Professor Gallego-Sala says they have been "overlooked" in some climate models because they are seen as "inert" -- neither absorbing nor emitting carbon at a rapid rate when left alone.This exclusion from models makes it hard to estimate future changes, so the study combined existing research with survey estimates from 44 leading peatland experts.Based on this, it estimates total carbon loss from 2020-2100 at 104 billion tons.The authors stress this estimate is highly uncertain (losses up to 360 billion tons to gains of 103 billion tons) -- but it demonstrates the need both for inclusion in models and better peatland preservation."Even though we would like more information, we clearly need to make decisions now about how we manage these ecosystems," Dr Gallego-Sala said."We simply can't afford for peatlands to go up in smoke."New "discoveries" of tropical peatlands in the Amazon and Congo are mainly intact, and the researchers say it is important to make sure we have solid policies in place."We have a responsibility to find a way forward that works for people and the planet," Dr Gallego-Sala said."Where people have a strong economic incentive -- or even necessity -- to destroy peatlands, we need plans and policies that offer more sustainable alternatives." | Climate | 2,020 |
December 7, 2020 | https://www.sciencedaily.com/releases/2020/12/201207102105.htm | Newly discovered Greenland plume drives thermal activities in the Arctic | A team of researchers understands more about the melting of the Greenland ice sheet. They discovered a flow of hot rocks, known as a mantle plume, rising from the core-mantle boundary beneath central Greenland that melts the ice from below. | The results of their two-part study were published in the "Knowledge about the Greenland plume will bolster our understanding of volcanic activities in these regions and the problematic issue of global sea-level rising caused by the melting of the Greenland ice sheet," said Dr. Genti Toyokuni, co-author of the studies.The North Atlantic region is awash with geothermal activity. Iceland and Jan Mayen contain active volcanoes with their own distinct mantle plumes, whilst Svalbard -- a Norwegian archipelago in the Arctic Ocean -- is a geothermal area. However, the origin of these activities and their interconnectedness has largely been unexplored.The research team discovered that the Greenland plume rose from the core-mantle boundary to the mantle transition zone beneath Greenland. The plume also has two branches in the lower mantle that feed into other plumes in the region, supplying heat to active regions in Iceland and Jan Mayen and the geothermal area in Svalbard.Their findings were based on measurements of the 3-D seismic velocity structure of the crust and whole mantle beneath these regions. To obtain the measurements, they used seismic topography. Numerous seismic wave arrival times were inverted to obtain 3-D images of the underground structure. The method works similarly to a CT scan of the human body.Toyokuni was able to utilize seismographs he installed on the Greenland ice sheet as part of the Greenland Ice Sheet Monitoring Network. Set up in 2009, the project sees the collaboration of researchers from 11 countries. The US-Japan joint team is primarily responsible for the construction and maintenance of the three seismic stations on the ice sheet.Looking ahead, Toyokuni hopes to explore the thermal process in more detail. "This study revealed the larger picture, so examining the plumes at a more localized level will reveal more information." | Climate | 2,020 |
December 4, 2020 | https://www.sciencedaily.com/releases/2020/12/201204131326.htm | The climate changed rapidly alongside sea ice decline in the north | Researchers from the Niels Bohr Institute, University of Copenhagen have, in collaboration with Norwegian researchers in the ERC Synergy project, ICE2ICE, shown that abrupt climate change occurred as a result of widespread decrease of sea ice. This scientific breakthrough concludes a long-lasting debate on the mechanisms causing abrupt climate change during the glacial period. It also documents that the cause of the swiftness and extent of sudden climate change must be found in the oceans. | During the last glacial period, app. 10,000 -- 110,000 years ago the northern hemisphere was covered in glacial ice and extensive sea ice, covering the Nordic seas. The cold glacial climate was interrupted by periods of fast warmup of up to 16.5 degrees Celsius over the Greenland ice sheet, the so called Dansgaard Oeschger events (D-O).These rapid glacial climate fluctuations were discovered in the Greenland ice core drillings decades ago, but the cause of them have been hotly contested. D-O events are of particular significance today as the rate of warming seems to be very much like what can be observed in large parts of the Arctic nowadays. The new results show that the abrupt climate change in the past was closely linked to the quick and extensive decline in sea ice cover in the Nordic seas. Very important knowledge as sea ice is presently decreasing each year."Our, up until now, most extensive and detailed reconstruction of sea ice documents the importance of the rapid decrease of sea ice cover and the connected feedback mechanisms causing abrupt climate change," says Henrik Sadatzki, first author of the study.The Norwegian researchers investigated two sediment cores from the Norwegian sea and the Danish researchers investigated an ice core from East Greenland for changes in the sea ice cover. Both sediment and ice cores were meticulously dated and further linked to one another through several volcanic layers of ash (tephra) identified in both.Past sea ice cover was reconstructed in the marine cores by observing the relation between specific organic molecules produced by algea living in sea ice and others by algea living in ice free waters. In the Renland ice core from East Greenland the researchers looked at the content of Bromin. This content is connected to newly formed sea ice, since Bromin contents increase when sea ice is formed. A robust chronology and sea ice information in both sediment cores and the ice core could be established and used to investigate the extent of the sea ice changes in the Nordic seas during the last glacial period."We have investigated how the sea ice cover changed during the last glacial period in both marine cores and ice cores. With the high resolution in our data sets we are able to see that the Nordic seas, during the rapid climate changes in the glacial period, change from being covered in ice all year round to having seasonal ice cover. This is knowledge we can apply in our improved understanding of how the sea ice decline we observe today may impact the climate in the Arctic," says Helle Astrid Kjær, Associate professor at the Ice, Climate and Geophysics section at the Niels Bohr Institute.The data the group of researchers present shows that the Nordic seas were covered by extensive sea ice in cold periods, while warmer periods are characterized by reduced, seasonal sea ice, as well as rather open ice free oceans. "Our records show that the extensive decline in sea ice could have happened during a period of 250 years or less, simultaneously with a phase in which the water in the oceans to the north mixed with the Nordic sea, and that this situation led to sudden changes in atmospheric warming," says Henrik Sadatzki.As the Nordic seas changed abruptly from ice covered to open sea, the energy from the warmer ocean water was released to the cold atmosphere, leading to amplification of sudden warming of the climate. The result of the study documents that sea ice is a "tipping element" in the tightly coupled ocean-ice-climate system. This is particularly relevant today, as the still more open ocean to the north can lead to similar abrupt climate change. | Climate | 2,020 |
December 4, 2020 | https://www.sciencedaily.com/releases/2020/12/201204131310.htm | Satellite tag tracks activity levels of highly migratory species across the vast ocean | Scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science and Wildlife Computers, Inc. have announced the release of a new activity data product application for marine animal tracking. The technology is designed to remotely track and transmit data gathered on an animal's activity levels over several months along with the temperatures and depths they experienced. | Determining if and how marine animals change their activity levels in response to varying environmental conditions like temperature is important for understanding and predicting their responses to global warming and other environmental changes."The new feature available on the Wildlife Computers MiniPAT pop-up tag has an integrated accelerometer for measuring activity, and its onboard software computes a summarized value of overall activity level, which can be transmitted to satellites," said Rachel Skubel, the study's lead author and a Doctoral student at UM's Abess Center for Ecosystem Science & Policy. "The Activity Time Series (ATS) data product allows us to determine when the tagged animal is switching from slow to fast swimming and vice versa."Wide-ranging ocean species, such as sharks, tunas, and billfish, lead complex lives hidden under the ocean surface. This makes studying activity levels in these species very challenging for scientists. While some tags have integrated accelerometers capable of measuring animal activity levels, the amount of raw data generated is generally too large to transmit via satellite, which required scientists to somehow retrieve the tags and download the accelerometer data. This has been a major limitation for gathering key data on how these species use their environment."Along with changes in activity level, the tag also collects and transmits data on the animal's swimming depth and the temperatures they encounter with a user-programmable resolution," said Kenady Wilson, Ph.D. research scientist, Wildlife Computers and a co-author of the study. "These data are transmitted via our MiniPAT (pop-up archival transmitting tag) with a tracking period of up to three months."This was truly a collaborative effort with the University of Miami and professor Hammerschlag's team," said Melinda Holland, CEO of Wildlife Computers. "This project demonstrates exactly what we do with the research community -- design, develop, test, and deliver a tag that meets the project's goals and objectives."To test the new ATS technology, researchers attached MiniPAT tags to cobia (Rachycentron canadum) housed at the University of Miami's Experimental Fish Hatchery. Using cameras to record the actual behaviors of the tagged cobia, researchers evaluated how changes in activity levels measured and transmitted by the ATS satellite tags matched the actual activity levels of the cobia recorded on camera. To see how well the tag performed in the wild, the team attached MiniPAT tags enabled with the ATS data product to sandbar sharks. After one month, the tags popped off as programed and successfully transmitted the sharks' activity data along with their environmental conditions and locations."The ability to now remotely track how animals are behaviorally responding to changes in environmental conditions over several months and across vast expanses of open ocean really opens up a lot of new research opportunities" said Neil Hammerschlag, research associate professor at the UM Rosenstiel School of Marine & Atmospheric Science and UM Abess Center for Ecosystem Science & Policy. "This is especially important for understanding if and how these species respond to climate change"The study, titled "A scalable, satellite-transmitted data product for monitoring high-activity events in mobile aquatic animals" was published on 22 November 2020 in the journal The study's authors include: Rachel Skubel, Daniel Benetti and Neil Hammerschlag at the University of Miami Rosenstiel School of Marine and Atmospheric Science, Kenady Wilson at Wildlife Computers, Yannis Papastamatiou at Florida International University, and Hannah Verkampp and James Sulikowski at Arizona State University.Rachel Skubel is supported by an NSERC PGS-D scholarship from the Government of Canada, a UM Fellowship from the University of Miami, and a Guy Harvey Scholarship from Florida Sea Grant and the Guy Harvey Ocean Foundation. This study was supported by a University of Miami Provost Grant. | Climate | 2,020 |
December 4, 2020 | https://www.sciencedaily.com/releases/2020/12/201201084748.htm | Bacteria in iron-deficient environments process carbon sources selectively | When humans have low iron levels, they tend to feel weak, fatigued and dizzy. This fatigue prevents patients with iron-deficient anemia from exercising or exerting themselves in order to conserve energy. | Similarly, in low-iron environments, microbes survive by slowing down carbon processing and extracting iron from minerals. However, this strategy requires microbes to invest precious food sources into producing mineral-dissolving compounds. Given this paradox, researchers wanted to understand how microbes sustain survival strategies in environments with too little iron to thrive.Iron is critical to carbon metabolism because it's required by the proteins involved in processing carbon. But because oxygen makes soluble iron less abundant in the environment, bacteria often operate under iron limitation and need to shut down or dramatically decrease carbon intake.Looking at a group of bacteria from soil, researchers at Northwestern University discovered that these organisms overcome limitation in their carbon processing machinery by rerouting their metabolic pathways to favor producing iron-scavenging compounds. The study is the first to use metabolomics, a high-resolution technique to monitor carbon flow in the cells, to study the impact of iron on the carbon cycling in bacterial cells.The study was published today (Nov. 30) in the journal Ludmilla Aristilde, an associate professor of civil and environmental engineering at the McCormick School of Engineering, led the research. Her research group focuses on understanding environmental processes that involve organics, with implications for ecosystem health, agricultural productivity and environmental biotechnology.Within the network of metabolism in bacteria, the citric acid cycle provides the carbon skeletons needed to make iron-scavenging compounds. Metabolism of certain carbon sources generates better carbon and fuel from the citric acid cycle. Iron-starved bacteria favor carbon processing through the citric acid cycle in order to produce more iron-scavenging compounds. Aristilde said this finding is significant because the research reveals that inorganic nutrients can have a direct impact on organic processes."The hierarchy in carbon metabolism highlights that selectivity in specific carbon usage is strongly linked to something that is inorganic," Aristilde said. "To put this in the context of climate change, we need to understand what conditions control soil carbon cycling and its contribution to carbon dioxide."By focusing on the Pseudomonas species in soils, the research group was able to make inferences about other species. The Pseudomonas bacteria also exist as human and plant pathogens, in our gut and elsewhere in the environment. Aristilde hopes that because the bacteria she and her researchers chose to study are so ubiquitous, future research will be able to use her group's findings as a roadmap.Past research studied organism behavior with a lower resolution of information. While scientists have used genomics to predict what may happen in metabolism of species based on identifying and measuring genes, the Aristilde lab uses metabolomics of the species to capture what is actually happening in metabolism. Their research provides clues that imply many other organisms and systems might also employ similar metabolic strategies.As an environmental engineer, Aristilde said that her area of study is all about understanding mechanisms and making predictions about how environmental processes like the carbon cycle behave. Beyond carbon cycling and climate change, the study also has implications in plant and human health. Understanding how bacteria that cause inflections change carbon metabolism to compete for iron in their plant or human hosts can enable researchers to better design target treatments.This study involved several students and researchers in the Aristilde lab, including current Ph.D. student Caroll Mendonca as the first author, former postdoctoral researcher Hua Wei, former M.S. student Samantha Sasnow and former undergraduate researchers Sho Yoshitake and Anne Werner as co-authors. The paper, "Hierarchical Routing in Carbon Metabolism Favors Iron-Scavenging Strategy in Iron-Deficient Soil Pseudomonas species," was supported by the National Science Foundation (award number CBET-1653092). | Climate | 2,020 |
December 3, 2020 | https://www.sciencedaily.com/releases/2020/12/201203144151.htm | How plants compete for underground real estate affects climate change and food production | You might have observed plants competing for sunlight -- the way they stretch upwards and outwards to block each other's access to the sun's rays -- but out of sight, another type of competition is happening underground. In the same way that you might change the way you forage for free snacks in the break room when your colleagues are present, plants change their use of underground resources when they're planted alongside other plants. | In a paper published today in "This study was a lot of fun because it combined several different kinds of mind candy to reconcile seemingly contradictory results in the literature: a clever experiment, a new method for observing root systems in intact soils and simple mathematical theory," said Stephen Pacala, the Frederick D. Petrie Professor in Ecology and Evolutionary Biology (EEB) and the senior author on the paper."While the aboveground parts of plants have been extensively studied, including how much carbon they can store, we know much less about how belowground parts -- that is, roots -- store carbon," said Cabal, a Ph.D. student in Pacala's lab. "As about a third of the world's vegetation biomass, hence carbon, is belowground, our model provides a valuable tool to predict root proliferation in global earth-system models."Plants make two different types of roots: fine roots that absorb water and nutrients from the soil, and coarse transportation roots that transport these substances back to the plant's center. Plant "investment" in roots involves both the total volume of roots produced and the way in which these roots are distributed throughout the soil. A plant could concentrate all of its roots directly beneath its shoots, or it could spread its roots out horizontally to forage in the adjacent soil -- which risks competition with the roots of neighboring plants.The team's model predicted two potential outcomes for root investment when plants find themselves sharing soil. In the first outcome, the neighboring plants "cooperate" by segregating their root systems to reduce overlap, which leads to producing less roots overall than they would if they were solitary. In the second outcome, when a plant senses reduced resources on one side due to the presence of a neighbor, it shortens its root system on that side but invests more in roots directly below its stem.Natural selection predicts this second scenario, because each plant acts to increase its own fitness, regardless of how those actions impact other individuals. If plants are very close together, this increased investment in root volume, despite segregation of those roots, could result in a tragedy of the commons, whereby the resources (in this case, soil moisture and nutrients) are depleted.To test the model's predictions, the researchers grew pepper plants in a greenhouse both individually and in pairs. At the end of the experiment, they dyed the roots of the plants different colors so that they could easily see which roots belonged to which plant. Then, they calculated the total biomass of each plant's root system and the ratio of roots to shoots, to see whether plants changed how much energy and carbon they deposited into belowground and aboveground structures when planted alongside neighbors, and counted the number of seeds produced by each plant as a measure of relative fitness.The team discovered that the outcome depends on how close a pair of plants are to each other. If planted very close together, plants will be more likely to heavily invest in their root systems to try to outcompete each other for finite underground resources; if they are planted further apart, they will likely invest less in their root systems than a solitary plant would.Specifically, they found that when planted near others, pepper plants increased investment in roots locally and reduced how far they stretched their roots horizontally, to reduce overlap with neighbors. There was no evidence for a "tragedy of the commons" scenario, since there was no difference in the total root biomass or relative investment in roots compared to aboveground structures (including the number of seeds produced per plant) for solitary versus co-habiting plants.Plants remove carbon dioxide from the atmosphere and deposit it in their structures -- and a third of this vegetative carbon is stored in roots. Understanding how carbon deposition changes in different scenarios could help us more accurately predict carbon uptake, which in turn could help design strategies to mitigate climate change. This research could also help optimize food production, because in order to maximize crop yield, it's helpful to understand how to optimally use belowground (and aboveground) resources. | Climate | 2,020 |
December 3, 2020 | https://www.sciencedaily.com/releases/2020/12/201203113243.htm | Robot fleet dives for climate answers in 'marine snow' | A fleet of new-generation, deep-diving ocean robots will be deployed in the Southern Ocean, in a major study of how marine life acts as a handbrake on global warming. | The automated probes will be looking for 'marine snow', which is the name given to the shower of dead algae and carbon-rich organic particles that sinks from upper waters to the deep ocean.Sailing from Hobart on Friday, twenty researchers aboard CSIRO's RV Investigator hope to capture the most detailed picture yet of how marine life in the Southern Ocean captures and stores carbon from the atmosphere.Voyage Chief Scientist, Professor Philip Boyd, from AAPP and IMAS, said it would be the first voyage of its kind to combine ship-board observations, deep-diving robots, automated ocean gliders and satellite measurements."The microscopic algae in the ocean are responsible for removing carbon dioxide from the atmosphere as much as the forests on land are," said Prof. Boyd."When they die, these tiny carbon-rich particles fall slowly to the ocean floor like a scene from a snow globe.""We are excited about how this combination of new imaging sensors will allow us to get a larger and much clearer picture of how ocean life helps to store carbon.""It's a bit like an astronomer who has only been able to study one star at a time suddenly being able to observe the galaxy in three-dimensions."Prof Boyd said the research would improve our understanding of a process scientists call the 'carbon pump', so named because it is responsible for pumping large volumes of carbon from the atmosphere into the ocean."We are just beginning to understand how the biological carbon pump works, but we know it helps in the removal of about a quarter of all the carbon dioxide that humans emit by burning fossil fuels. ""During the voyage, we will deploy a fleet of deep-diving robotic floats and gliders that use new bio-optical sensors to 'photograph' the density of the algae at different depths.""When they return to the ocean surface, these floats will immediately transmit their data back to us via satellite.""It is a major step forward in our ability to measure carbon uptake by marine life," said Prof. Boyd.The Southern Ocean Large Areal Carbon Export (SOLACE) voyage is scheduled to depart on Friday 04 December.The project includes contributions from CSIRO, the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS), the Australian National University (ANU), Curtin University and the Australian Antarctic Program Partnership (AAPP).This research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility. | Climate | 2,020 |
December 3, 2020 | https://www.sciencedaily.com/releases/2020/12/201203113226.htm | Coasts drown as coral reefs collapse under warming and acidification | A new study shows the coastal protection coral reefs currently provide will start eroding by the end of the century, as the world continues to warm and the oceans acidify. | A team of researchers led by Associate Professor Sophie Dove from the ARC Centre of Excellence for Coral Reef Studies at The University of Queensland (Coral CoE at UQ) investigated the ability of coral reef ecosystems to retain deposits of calcium carbonate under current projections of warming and ocean acidification.Calcium carbonate is what skeletons are made of -- and it dissolves under hot, acidic conditions. Marine animals that need calcium carbonate for their skeletons or shells are called 'calcifiers'. Hard corals have skeletons, which is what gives reefs much of their three-dimensional (3D) structure. It's this structure that helps protect coasts -- and those living on the coasts -- from the brunt of waves, floods and storms. Without coral reefs the coasts 'drown'.A/Prof Dove says the amount of calcium carbonate within a coral reef ecosystem depends on the biomass of hard corals. But it also depends on the combined impact of warming and acidification on previously deposited calcium carbonate frameworks. She says the results of the study indicate the rate of erosion will overtake the rate of accretion on the majority of present-day reefs."Today's Great Barrier Reef has a 30% calcifier cover," A/Prof Dove said."If CO"In addition, more than 110% calcifier cover is needed to keep up with the minimal levels of sea-level rise."However, A/Prof Dove says both of these scenarios are unlikely because high amounts of hard corals perish with intense underwater heatwaves. Previous studies show marine heatwaves will become chronic in the warmer months of an average year under unmitigated COThe study was published in today's Communications Earth & Environment, just after the IUCN World Heritage Outlook 3 rated the Great Barrier Reef as 'critical'.A/Prof Dove and her team built experimental reefs closely resembling those of shallow reef slopes at Heron Island on the southern Great Barrier Reef. For 18 months, they studied the effects of future climate scenarios on the ecosystem."What we saw was the insidious and accelerated loss of coastal protection under unmitigated CO"Under current projections, reefs will not simply adapt. Chronic exposure to the combined impacts of ocean warming and acidification will weaken reefs. They won't be able to re-build after disturbances such as cyclones, nor will they keep up with sea-level rise -- possibly for thousands of years," said co-author Dr Kristen Brown, also from Coral CoE at UQ.This means many coastal areas currently protected by calcareous coral reefs will no longer be so, impacting coastal infrastructure and communities."The combined impact of warming with the acidification of our oceans will see more than the collapse of ecosystems," A/Prof Dove said. | Climate | 2,020 |
December 3, 2020 | https://www.sciencedaily.com/releases/2020/12/201203094531.htm | Cluster of Alaskan islands could be single, interconnected giant volcano | A small group of volcanic islands in Alaska's Aleutian chain might be part of a single, undiscovered giant volcano, say scientists presenting the findings Monday, 7 December at AGU's Fall Meeting 2020. If the researchers' suspicions are correct, the newfound volcanic caldera would belong to the same category of volcanoes as the Yellowstone Caldera and other volcanoes that have had super-eruptions with severe global consequences. | The Islands of the Four Mountains in the central Aleutians is a tight group of six stratovolcanoes named Carlisle, Cleveland, Herbert, Kagamil, Tana and Uliaga. Stratovolcanoes are what most people envision when they think of a volcano: a steep conical mountain with a banner of clouds and ash waving at the summit. They can have powerful eruptions, like that of Mount St. Helens in 1980, but these are dwarfed by far less frequent caldera-forming eruptions.Researchers from a variety of institutions and disciplines have been studying Mount Cleveland, the most active volcano of the group, trying to understand the nature of the Islands of the Four Mountains. They have gathered multiple pieces of evidence showing that the islands could belong to one interconnected caldera.Unlike stratovolcanoes, which tend to tap small- to modestly-sized reservoirs of magma, a caldera is created by tapping a huge reservoir in the Earth's crust. When the reservoir's pressure exceeds the strength of the crust, gigantic amounts of lava and ash are released in a catastrophic episode of eruption.Caldera-forming eruptions are the most explosive volcanic eruptions on Earth and they often have had global effects. The ash and gas they put into the atmosphere can affect Earth's climate and trigger social upheaval. For example, the eruption of nearby Okmok volcano in the year BCE 43 has been recently implicated in the disruption of the Roman Republic. The proposed caldera underlying the Islands of the Four Mountains would be even larger than Okmok. If confirmed, it would become the first in the Aleutians that is hidden underwater, said Diana Roman of the Carnegie Institution for Science in Washington, D.C., co-author of the study."We've been scraping under the couch cushions for data," said Roman, referring to the difficulty of studying such a remote place. "But everything we look at lines up with a caldera in this region."Despite all these signs, Roman along with John Power, a researcher with the U.S. Geological Survey at the Alaska Volcano Observatory and the study's lead author, maintain that the existence of the caldera is not by any means proven. To do that the study team will need to return to the islands and gather more direct evidence to fully test their hypothesis."Our hope is to return to the Islands of Four Mountains and look more closely at the seafloor, study the volcanic rocks in greater detail, collect more seismic and gravity data, and sample many more of the geothermal areas," Roman said.The caldera hypothesis might also help explain the frequent explosive activity seen at Mount Cleveland, Roman said. Mount Cleveland is arguably the most active volcano in North America for at least the last 20 years. It has produced ash clouds as high as 15,000 and 30,000 feet above sea level. These eruptions pose hazards to aircraft traveling the busy air routes between North America and Asia."It does potentially help us understand what makes Cleveland so active," said Power, who will present the work. "It can also help us understand what type of eruptions to expect in the future and better prepare for their hazards." | Climate | 2,020 |
December 3, 2020 | https://www.sciencedaily.com/releases/2020/12/201202114456.htm | Study shows promising material can store solar energy for months or years | As we move away from fossil fuels and shift to renewable energy to tackle climate change, the need for new ways to capture and store energy becomes increasingly important. | Lancaster University researchers studying a crystalline material have discovered it has properties that allow it to capture energy from the sun. The energy can be stored for several months at room temperature, and it can be released on demand in the form of heat.With further development, these kinds of materials could offer exciting potential as a way of capturing solar energy during the summer months, and storing it for use in winter -- where less solar energy is available.This would prove invaluable for applications such as heating systems in off-grid systems or remote locations, or as an environmentally-friendly supplement to conventional heating in houses and offices. It could potentially also be produced as a thin coating and applied to the surface of buildings, or used on the windscreens of cars where the stored heat could be used to de-ice the glass in freezing winter mornings.The material is based on a type of 'metal-organic framework' (MOF). These consist of a network of metal ions linked by carbon-based molecules to form 3-D structures. A key property of MOFs is that they are porous, meaning that they can form composite materials by hosting other small molecules within their structures.The Lancaster research team set out to discover if a MOF composite, previously prepared by a separate research team at Kyoto University in Japan and known as 'DMOF1', can be used to store energy -- something not previously researched.The MOF pores were loaded with molecules of azobenzene -- a compound that strongly absorbs light. These molecules act as photoswitches, which are a type of 'molecular machine' that can change shape when an external stimulus, such as light or heat, is applied.In tests, the researchers exposed the material to UV light, which causes the azobenzene molecules to change shape to a strained configuration inside the MOF pores. This process stores the energy in a similar way to the potential energy of a bent spring. Importantly, the narrow MOF pores trap the azobenzene molecules in their strained shape, meaning that the potential energy can be stored for long periods of time at room temperature.The energy is released again when external heat is applied as a trigger to 'switch' its state, and this release can be very quick -- a bit like a spring snapping back straight. This provides a heat boost which could be used to warm other materials of devices.Further tests showed the material was able to store the energy for at least four months. This is an exciting aspect of the discovery as many light-responsive materials switch back within hours or a few days. The long duration of the stored energy opens up possibilities for cross-seasonal storage.The concept of storing solar energy in photoswitches has been studied before, but most previous examples have required the photoswitches to be in a liquid. Because the MOF composite is a solid, and not a liquid fuel, it is chemically stable and easily contained. This makes it much easier to develop into coatings or standalone devices.Dr John Griffin, Senior Lecturer in Materials Chemistry at Lancaster University and joint Principal Investigator of the study, said: "The material functions a bit like phase change materials, which are used to supply heat in hand warmers. However, while hand warmers need to be heated in order to recharge them, the nice thing about this material is that it captures "free" energy directly from the sun. It also has no moving or electronic parts and so there are no losses involved in the storage and release of the solar energy. We hope that with further development we will be able to make other materials which store even more energy."These proof-of-concept findings open up new avenues of research to see what other porous materials might have good energy storage properties using the concept of confined photoswitches.Joint investigator Dr Nathan Halcovitch added: "Our approach means that there are a number of ways to try to optimise these materials either by changing the photoswitch itself, or the porous host framework."Other potential applications for crystalline materials containing photoswitch molecules include data storage -- the well-defined arrangement of photoswitches in the crystal structure means that they could in principle be switched one-by-one using a precise light source and therefore store data like on a CD or DVD, but at a molecular level. They also have potential for drug delivery -- drugs could be locked inside a material using photoswitches and then released on demand inside the body using a light or heat trigger.Although the results were promising for this material's ability to store energy for long periods of time, its energy density was modest. Next steps are to research other MOF structures as well as alternative types of crystalline materials with greater energy storage potential.The research, which was supported by the Leverhulme Trust, is outlined in the paper 'Long-Term Solar Energy Storage under Ambient Conditions in a MOF-Based Solid-Solid Phase Change Material', which has been published by the journal The researchers are John Griffin, Kieran Griffiths and Nathan Halcovitch, all of Lancaster University's Department of Chemistry. | Climate | 2,020 |
December 2, 2020 | https://www.sciencedaily.com/releases/2020/12/201202192734.htm | Nanomaterials enable dual-mode heating and cooling device | Engineers at Duke University have demonstrated a dual-mode heating and cooling device for building climate control that, if widely deployed in the U.S., could cut HVAC energy use by nearly 20 percent. | The invention uses a combination of mechanics and materials science to either harness or expel certain wavelengths of light. Depending on conditions, rollers move a sheet back and forth to expose either heat-trapping materials on one half or cooling materials on the other. Specially designed at the nanoscale, one material absorbs the sun's energy and traps existing heat, while the other reflects light and allows heat to escape through the Earth's atmosphere and into space."I think we are the first to demonstrate a reversible thermal contact, which allows us to switch between the two modes for heating or cooling," said Po-Chun Hsu, assistant professor of mechanical engineering and materials science at Duke and leader of the team. "This allows the material to be movable while still maintaining a good thermal contact with the building to either bring heat in or let heat out."The results appeared online November 30, in the journal About 15% of energy consumption in the U.S., and more than 30% globally, is for the heating and cooling of buildings, which is responsible for about 10% of global greenhouse gas emissions. Yet, up to now, most approaches to minimize the carbon footprint have only addressed either heating or cooling. That leaves the world's temperate climate zones that require both heating and cooling during the year -- or sometimes in a single 24 hours -- out in the cold. In the new paper, Hsu and his team demonstrate a device that potentially could keep us either cozy or cool as the weather changes.The specially designed sheet starts with a polymer composite as the base that can expand or contract by running electricity through it. This allows the device to maintain contact with the building for transmitting energy while still being able to disengage so that the rollers can switch between modes.The cooling portion of the sheet has an ultra-thin silver film covered by an even thinner layer of clear silicone, which together reflect the sun's rays like a mirror. The unique properties of these materials also convert energy into and emit mid-range infrared light, which does not interact with the gasses in the Earth's atmosphere and easily passes into outer space.When a change in weather brings the need for heating, the electrical charge releases and the rollers pull the sheet along a track. This swaps the cooling, reflective half of the sheet for the heat-absorbing half.To heat the building beneath, the engineers used an ultra-thin layer of copper topped by a layer of zinc-copper nanoparticles. By making the nanoparticles a specific size and spacing them a certain distance apart, they interact with the copper beneath them in a way that traps light onto their surface, allowing the material to absorb more than 93% of the sunlight's heat.Hsu and his team see the device as something that could work with existing HVAC systems, rather than a full replacement."Instead of directly heating and cooling the building, we could use a water panel to take hot or cold water to a heat pump or boiler system," said Hus. "I also imagine that with additional engineering, this could also be used on walls, forming a sort of switchable building envelop." said Hsu.Moving forward, the team is working on several aspects of the design to advance it from a prototype to one scalable for manufacturing. Among these, explained Hsu, are concerns about the long-term wear and tear of the moving parts and costs of the specialized materials. For example, they will investigate whether lower-cost aluminum can substitute for the silver and are also working on a static version that can switch modes chemically rather than mechanically.Despite the many obstacles, Hsu believes this technology could be an energy-saving boon in the future. And he's not alone."We're already working with a company to determine the ideal locations for deploying this technology," said Hsu. "And because almost every climate zone in the United States requires both heating and cooling at some point throughout the year, the advantages of a dual-mode device such as this are obvious." | Climate | 2,020 |
December 2, 2020 | https://www.sciencedaily.com/releases/2020/12/201202192702.htm | Once in a lifetime floods to become regular occurrences by end of century | Superstorm Sandy brought flood-levels to the New York region that had not been seen in generations. Causing an estimated $74.1 billion in damages, it was the fourth-costliest U.S. storm behind Hurricane Katrina in 2005 and hurricanes Harvey and Maria in 2017 according to the National Oceanic and Atmospheric Administration. Now, due to the impact of climate change, researchers at Stevens Institute of Technology have found that 100-year and 500-year flood levels could become regular occurrences for the thousands of homes surrounding Jamaica Bay, New York by the end of the century. | The study, led by Reza Marsooli, assistant professor of civil, environmental and ocean engineering at Stevens, can help policymakers and the coastal municipality of Jamaica Bay make decisions on whether to apply coastal flood defenses or other planning strategies or policies for reducing future risk. It also provides an example of the extent of how coastal flooding will increase in the future across the New York region and other areas due to the impacts of climate change."While this study was specific to Jamaica Bay, it shows how drastic and costly of an impact that climate change will make," said Marsooli, whose work appears in the Nov. 26 issue of Based on the anticipated greenhouse gas concentration by the end of the 21st century, Marsooli and his co-author Ning Lin, from Princeton University, conducted high resolution simulations for different scenarios to find the probability of different flood levels being reached, assuming emissions remain at a high level. They studied how sea level rise and hurricane climatology change would impact the area in the future due to storm surge and wave hazards.Marsooli and Lin found that the historical 100-year flood level would become a nine-year flood level by mid-century (2030-2050) and a one-year flood level by late 21st century (2080-2100). Most recently reached by Superstorm Sandy, 500-year flood levels would become a 143-year flood level, and then a four-year flood level by the end of the century. Additionally, sea-level rise would result in larger waves which could lead to more flood hazards such as erosion and damage to coastal infrastructure."Future projections of the hurricane climatology suggest that climate change would lead to storms that move more slowly and are more intense than we have ever seen before hitting Jamaica Bay," said Marsooli. "But the increase in these once-in-a-generation or even less frequent floods is so dramatic because the impact of sea-level rise will create greater flooding, even if the storms we were seeing today stayed the same." | Climate | 2,020 |
December 2, 2020 | https://www.sciencedaily.com/releases/2020/12/201202114448.htm | Greenland ice sheet faces irreversible melting | In a study published this week in | The massive ice sheet faces a point of no return, beyond which it will no longer fully regrow, permanently changing sea levels around the world.The Greenland ice sheet is seven times the area of the UK, and stores a large amount of the Earth's frozen water. At current rates of melting, it contributes almost 1mm to sea level per year, and accounts for around a quarter of total sea level rise.Since 2003, despite seasonal periods of growth, Greenland's ice sheet has lost three and a half trillion tonnes of ice.Rising sea levels are one of the most severe effects of climate change, threatening coastal areas around the world, and putting millions of people who live in low-lying areas at risk. Bangladesh, Florida, and eastern England are among many areas known to be particularly vulnerable.Under scenarios in which global warming goes beyond 2°C, the Paris Agreement target, we should expect significant ice loss and several metres of global sea level rise to persist for tens of thousands of years, according to the new research. The warmer the climate, the greater the sea-level rise.In addition, even if temperatures later return to current levels, scientists have shown that the Greenland ice sheet will never fully regrow once it melts beyond a critical point. After that point, sea levels would permanently remain two meters higher than now, regardless of other factors contributing to sea level rise.This is because the ice sheet is so large that it has a substantial impact on its local climate, and as it declines, Greenland would experience warmer temperatures and less snowfall.Once the ice-sheet retreats from the Northern part of the island, the area would remain ice-free.To avoid the irreversible sea level rise the melting would cause, scientists say that climate change must be reversed before the ice sheet has declined to the threshold mass, which would be reached in about 600 years at the highest rate of mass loss within the likely range of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.Professor Jonathan Gregory, Climate Scientist from the National Centre for Atmospheric Science and University of Reading, said: "Our experiments underline the importance of mitigating global temperature rise. To avoid partially irreversible loss of the ice sheet, climate change must be reversed -- not just stabilised -- before we reach the critical point where the ice sheet has declined too far."To study the ice-sheet, scientists from the National Centre for Atmospheric Science simulated the effects of Greenland ice sheet melting under a range of possible temperature rises, ranging from minimal warming to worst-case scenarios.Under all future climates like the present or warmer, the ice-sheet declined in size and contributed to some degree of sea-level rise.Importantly, there were scenarios in which the ice sheet melting could be reversed. But, they rely on actions to counteract global warming before it's too late.This is the first time that the Greenland ice-sheet has been studied in such detail, using a computer model that combines climate and ice-sheet models. | Climate | 2,020 |
December 1, 2020 | https://www.sciencedaily.com/releases/2020/12/201201153424.htm | Geoscientists use zircon to trace origin of Earth's continents | Geoscientists have long known that some parts of the continents formed in the Earth's deep past, but the speed in which land rose above global seas -- and the exact shapes that land masses formed -- have so far eluded experts. | But now, through analyzing roughly 600,000 mineral analyses from a database of about 7,700 different rock samples, a team led by Jesse Reimink, assistant professor of geosciences at Penn State, thinks they're getting closer to the answers.The researchers say that Earth's land masses began to slowly rise above sea level about 3 billion years ago. When their interpretation is combined with previous work, including work from other Penn State researchers, it suggests that continents took roughly 500 million years to rise to their modern heights, according to findings recently published in To reach this conclusion, scientists applied a unique statistical analysis to crystallization ages from the mineral zircon, which is reliably dateable and is frequently found in sedimentary rocks. While these researchers did not date these samples, the samples were all dated using the the uranium-lead decay system. This method measures the amount of lead in a sample and calculates from the well established rate of uranium decay, the age of the crystal. When zirconium forms, no lead is incorporated into its structure, so any lead is from uranium decay.The minerals found in the sedimentary rock samples originally formed in older magmas but, through erosion and transport, traveled in rivers and were eventually deposited in the ocean where they were turned into sedimentary rock beneath the surface of the sea floor. The ages of zircons retrieved from individual rock samples can be used to tell the type of continent they were eroded from.The ages of zircons from Eastern North American rocks are, for instance, different from those of land masses such as Japan, which was formed by much more recent volcanic activity."If you look at the Mississippi River, it's eroding rocks and zircons from all over North America. It's gathering mineral grains that have a massive age range from as young as a million years to as old as a few billions of years," Reimink said. "Our analysis suggests that as soon as sediment started to be formed on Earth they were formed from sedimentary basins with a similarly large age range."Sediments are formed from weathering of older rocks, and carry the signature of past landmass in time capsules such as zircons. The research doesn't uncover the overall size of primordial continents, but it does speculate that modern-scale watersheds were formed as early as 2.7 billion years ago."Our research matches nicely with the preserved rock record," Reimink said.This finding is critical for a few reasons. First, knowing when and how the continents formed advances research on the carbon cycle in the land, water and atmosphere. Secondly, it gives us clues as to the early origins of Earth. That could prove useful as we discover more about life and the formation of other planets. Earth is a life-sustaining planet, in part, because of how continental crust influences our atmospheric and oceanic composition. Knowing how and when these processes occurred could hold clues to the creation of life."Whenever we're able to determine processes that led to our existence, it relates to the really profound questions such as: Are we unique? Is Earth unique in the universe? And are there other Earths out there," Reimink said. "These findings help lead us down the path to the answers we need about Earth that allow us to compare our planet to others."The Natural Sciences and Engineering Research Council of Canada partially supported this work. | Climate | 2,020 |
December 1, 2020 | https://www.sciencedaily.com/releases/2020/12/201201144056.htm | What will the climate be like when Earth's next supercontinent forms? | Long ago, all the continents were crammed together into one large land mass called Pangea. Pangea broke apart about 200 million years ago, its pieces drifting away on the tectonic plates -- but not permanently. The continents will reunite again in the deep future. And a new study, presented today during an online poster session at the meeting of the American Geophysical Union, suggests that the future arrangement of this supercontinent could dramatically impact the habitability and climate stability of Earth. The findings also have implications for searching for life on other planets. | The study, which has been submitted for publication, is the first to model the climate on a supercontinent in the deep future.Scientists aren't exactly sure what the next supercontinent will look like or where it will be located. One possibility is that, 200 million years from now, all the continents except Antarctica could join together around the north pole, forming the supercontinent "Amasia." Another possibility is that "Aurica" could form from all the continents coming together around the equator in about 250 million years.In the new study, researchers used a 3D global climate model to simulate how these two land mass arrangements would affect the global climate system. The research was led by Michael Way, a physicist at the NASA Goddard Institute for Space Studies, an affiliate of Columbia University's Earth Institute.The team found that, by changing atmospheric and ocean circulation, Amasia and Aurica would have profoundly different effects on the climate. The planet could end up being 3 degrees Celsius warmer if the continents all converge around the equator in the Aurica scenario.In the Amasia scenario, with the land amassed around both poles, the lack of land in between disrupts the ocean conveyor belt that currently carries heat from the equator to the poles. As a result, the poles would be colder and covered in ice all year long. And all of that ice would reflect heat out into space.With Amasia, "you get a lot more snowfall," explained Way. "You get ice sheets, and you get this very effective ice-albedo feedback, which tends to lower the temperature of the planet."In addition to cooler temperatures, Way suggested that sea level would probably be lower in the Amasia scenario, with more water tied up in the ice caps, and that the snowy conditions could mean that there wouldn't be much land available for growing crops.Aurica, by contrast, would probably be a bit beachier, he said. The land concentrated closer to the equator would absorb the stronger sunlight there, and there would be no polar ice caps to reflect heat out of Earth's atmosphere -- hence the higher global temperature.Although Way likens Aurica's shores to the paradisiacal beaches of Brazil, "the inland would probably be quite dry," he warned. Whether or not much of the land would be farmable would depend on the distribution of lakes and what types of precipitation patterns it experiences -- details that the current paper doesn't delve into, but could be investigated in the future.The simulations showed that temperatures were right for liquid water to exist on about 60% of Amasia's land, as opposed to 99.8% of Aurica's -- a finding that could inform the search for life on other planets. One of the main factors that astronomers look for when scoping out potentially habitable worlds is whether or not liquid water could survive on the planet's surface. When modeling these other worlds, they tend to simulate planets that are either completely covered in oceans, or else whose terrain looks like that of modern-day Earth. The new study, however, shows that it's important to consider land mass arrangements while estimating whether temperatures fall in the 'habitable' zone between freezing and boiling.Although it may be 10 or more years before scientists can ascertain the actual land and sea distribution on planets in other star systems, the researchers hope that having a larger library of land and sea arrangements for climate modeling could prove useful in estimating the potential habitability of neighboring worlds.Hannah Davies and Joao Duarte from the University of Lisbon, and Mattias Green from Bangor University in Wales were co-authors on this research. | Climate | 2,020 |
December 1, 2020 | https://www.sciencedaily.com/releases/2020/12/201201124229.htm | Cost of planting, protecting trees to fight climate change could jump | Planting trees and preventing deforestation are considered key climate change mitigation strategies, but a new analysis finds the cost of preserving and planting trees to hit certain global emissions reductions targets could accelerate quickly. | In the analysis, researchers from RTI International (RTI), North Carolina State University and Ohio State University report costs will rise steeply under more ambitious emissions reductions plans. By 2055, they project it would cost as much as $393 billion per year to pay landowners to plant and protect enough trees to achieve more than 10 percent of total emissions reductions that international policy experts say are needed to restrict climate change to 1.5 degrees Celsius. The findings were published today in the journal "The global forestry sector can provide a really substantial chunk of the mitigation needed to hit global climate targets," said Justin Baker, co-author of the study and associate professor of forest resource economics at NC State. "The physical potential is there, but when we look at the economic costs, they are nonlinear. That means that the more we reduce emissions -- the more carbon we're sequestering -- we're paying higher and higher costs for it."The researchers found that The Intergovernmental Panel on Climate Change expects forestry to play a critical role in reducing climate change. To analyze the cost of preserving forest, preventing harvest and deforestation, and planting trees, researchers used a price model called the Global Timber Model. That model estimates costs of preserving trees in private forests owned and managed by companies for harvesting for pulp and paper products, as well as on publicly owned land, such as U.S. national parks."Protecting, managing and restoring the world's forests will be necessary for avoiding dangerous impacts of climate change, and have important co-benefits such as biodiversity conservation, ecosystem service enhancement and protection of livelihoods," said Kemen Austin, lead author of the study and senior policy analyst at RTI. "Until now, there has been limited research investigating the costs of climate change mitigation from forests. Better understanding the costs of mitigation from global forests will help us to prioritize resources and inform the design of more efficient mitigation policies."The researchers estimated it would cost $2 billion per year to prevent 0.6 gigatons of carbon dioxide from being released by 2055. Comparatively, $393 billion annually would sequester 6 gigatons, or the equivalent of emissions from nearly 1.3 billion passenger vehicles driven for one year, according to the U.S. Environmental Protection Agency's Greenhouse Gas Equivalencies Calculator."It's not clear from these results that you'll have consistent low-cost mitigation from the global forest sector as other studies have indicated," Baker said.The tropics are expected to play the biggest role in reducing emissions, with Brazil -- the country that contains the largest share of the Amazon rainforest -- the Democratic Republic of Congo, and Indonesia contributing the largest share. The tropics will contribute between 72 and 82 percent of total global mitigation from forestry in 2055.The researchers also found that forest management in temperate regions, such as forestland in the southern United States, will play a significant role, especially under higher price scenarios. They expect that afforestation, which is introducing trees to areas that are not actively in forest, and managing existing forestland will be important strategies in the United States. | Climate | 2,020 |
December 1, 2020 | https://www.sciencedaily.com/releases/2020/12/201201124138.htm | Octogenarian snapper found off Australia becomes oldest tropical reef fish by two decades | An 81-year-old midnight snapper caught off the coast of Western Australia has taken the title of the oldest tropical reef fish recorded anywhere in the world. | The octogenarian fish was found at the Rowley Shoals -- about 300km west of Broome -- and was part of a study that has revised what we know about the longevity of tropical fish.The research identified 11 individual fish that were more than 60 years old, including a 79-year-old red bass also caught at the Rowley Shoals.Australian Institute of Marine Science (AIMS) Fish Biologist Dr Brett Taylor, who led the study, said the midnight snapper beat the previous record holder by two decades."Until now, the oldest fish that we've found in shallow, tropical waters have been around 60 years old," he said."We've identified two different species here that are becoming octogenarians, and probably older."Dr Taylor said the research will help us understand how fish length and age will be affected by climate change."We're observing fish at different latitudes -- with varying water temperatures -- to better understand how they might react when temperatures warm everywhere," he said.The study involved four locations along the WA coast, as well as the protected Chagos Archipelago in the central Indian Ocean.It looked at three species that are not targeted by fishing in WA; the red bass (Lutjanus bohar), midnight snapper (Macolor macularis), and black and white snapper (Macolor niger).Co-author Dr Stephen Newman, from the WA Department of Primary Industries and Regional Development, said long-lived fish were generally considered more vulnerable to fishing pressure."Snappers make up a large component of commercial fisheries in tropical Australia and they're also a key target for recreational fishers," he said."So, it's important that we manage them well, and WA's fisheries are among the best managed fisheries in the world."Marine scientists are able to accurately determine the age of a fish by studying their ear bones, or 'otoliths'.Fish otoliths contain annual growth bands that can be counted in much the same way as tree rings.Dr Taylor said the oldest red bass was born during World War I."It survived the Great Depression and World War II," he said."It saw the Beatles take over the world, and it was collected in a fisheries survey after Nirvana came and went.""It's just incredible for a fish to live on a coral reef for 80 years." | Climate | 2,020 |
December 1, 2020 | https://www.sciencedaily.com/releases/2020/12/201201124117.htm | New research reveals 'megatrends' that will affect forests in the next decade | A group of experts from academic, governmental and international organisations have identified five large-scale 'megatrends' affecting forests and forest communities, published today in | Around the world, 1.6 billion people live within 5km of a forest, and millions rely on them for their livelihoods, especially in poorer countries. They are also home to much of the world's biodiversity, and regulate key aspects of the carbon cycle. In short, forests are vital in global and national efforts to combat climate change and biodiversity loss, and eradicate hunger and poverty.Despite their importance, research on forests and livelihoods to date has mainly focused on understanding local household and community-level dynamics -- identifying the links between human and natural systems at the regional and global scales is critical for future policy and action.The five trends revealed by the research are:Droughts and excessive precipitation are increasing forests' susceptibility to diseases and human-induced wildfires and floods -- this is leading to defoliation, tree mortality and declines in forest productivity at unprecedented scales, and there is increasing evidence that forest disturbance can result in the emergence of diseases with the ability to spread globally.Policy responses to these disturbances will require balancing a range of mitigation and adaptation efforts -- whilst opportunities and challenges are likely to arise from efforts to align forest conservation and restoration with other sustainability priorities, such as poverty alleviation.Increased migration to urban areas is causing an unprecedented exodus among forest-reliant communities. The effects of these demographic shifts, including forest resurgence on formerly agricultural lands and participation in decision-making, are not well understood.Populations shifts could result in opportunities for effective forest conservation, whilst on the other hand could lead to deforestation as greater urban demand and large industrial projects are created.By 2030 the middle class in low and middle income countries will grow to almost 5 billion people -- around 50% of the global population. The growth in demand that this creates will increase pressure on land and other resources.Growing consumption and demand of commodities has already seen large scale corporate-led land acquisitions for industrial production of cattle, soy and palm oil in Latin America, Africa and Southeast Asia. Between 2001-2015, 27% of forest disturbance was attributed to commodity-driven deforestation. Further growth in demand and a continuing culture of consumerism will alter local and global consumption patterns, with potentially severe effects on deforestation rates, emissions, wildlife populations, ecosystem services and rural communities.Access to digital communication technology has grown exponentially in recent years, with a sevenfold increase in internet and mobile cellular use since 2000. The majority of this growth has come outside industrialised countries, and is likely to have a transformational impact on the forest sector. Technologies that collect and disseminate data are increasingly accurate and easy-to-use, including land mapping tools, real-time satellite data and crowd-sourced data.Although they can be accessed by those involved in illicit activity such as logging and mining, these technologies also provide opportunities. Increasingly available data can benefit a wide range of forest sector stakeholders including policymakers, oversight bodies, non-governmental actors, managers and local communities. New technologies are already supporting the surveillance and certification of global production networks, which is aiding regulatory control of forest-based products and people threatening forests.Large scale infrastructure projects such as China's Belt and Road initiative are likely to have transformational impacts on forests and rural communities. To accommodate demand for energy, natural resources and transport, many countries have planned ambitious infrastructure growth.By 2050, there is expected to be at least 25 million km of new roads globally to help facilitate commodity flow between transport hubs; governments in the Amazon basin alone are developing 246 new hydroelectric dams; and illegal mining activities are expanding rapidly across the globe. These can lead to forest loss, displaces people, disrupts livelihoods and provokes social conflicts as communities lose access to land and resources.These five megatrends are creating new agricultural and urban frontiers, changing landscapes, opening spaces for conservation and facilitating an unprecedented development of monitoring platforms that can be used by local communities, civil society organisations, governments and international donors. Understanding these larger-scale dynamics is key to support not only the critical role of forests in meeting livelihood aspirations locally, but also a range of other sustainability challenges globally."Our study allows us to take stock of key socioeconomic, political and environmental issues affecting forests and rural communities, and identify trends likely to have disproportionate impacts on forests and forest-livelihoods in the coming decade," says Johan Oldekop, an associate professor in the Global Development Institute at the University of Manchester and a lead author of the report."The trends we identify are important, because they represent human and environmental processes that are exceptionally large in geographical extent and magnitude, and are difficult to reverse," Oldekop says. "Developing a new research agenda that is able to better understand these trends and identify levers of change will require novel ways of combining new and existing data sources, the strengthening of existing collaborations between researchers, local communities and policymakers, as well as the development of new types of partnerships with public and private stakeholders.""The assembled expert panel is unique as it brings together a range of subject expertise, region-specific knowledge, as well as academic, governmental and non-governmental institutions, including international donor organizations," adds Laura Vang Rasmussen, an assistant professor in the Department of Geosciences and Natural Resource Management at the University of Copenhagen, and one of the lead authors of the report. | Climate | 2,020 |
December 1, 2020 | https://www.sciencedaily.com/releases/2020/12/201201124056.htm | Watching the Arctic thaw in fast-forward | The Arctic is warming more quickly than almost any other region on Earth as a result of climate change. One of the better known: the continually shrinking summer sea-ice extent in the Arctic. But global warming is also leaving its mark on terrestrial permafrost. For several years, permafrost regions have been thawing more and more intensively in North America, Scandinavia and Siberia -- e.g. in the extreme northwest of Alaska. Permafrost is soil that has remained permanently frozen to depths of up to several hundred metres, often since the last glacial period, roughly 20,000 years ago, or in some cases even longer. | The permafrost regions near the city of Kotzebue, Alaska, are dotted with hundreds of thaw lakes. These are formed when the permafrost soils begin to thaw and subside. Meltwater from the soil or from the winter snowfall and summer rainfall collects in the hollows. Some are several thousand years old and were formed since the end of the last glacial period. But in recent years, the lake landscape has changed due to more frequent relatively mild winters there. In summer, the permafrost soils thaw extensively and they don't completely refreeze in winter, which means that the lakes' shores become unstable and collapse, causing water to drain from the lakes. Researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) observed a particularly extreme example of this in the seasons 2017 and 2018: within a year, more lakes drained than ever before -- roughly 190 in total. "The scale shocked us," says AWI geographer Ingmar Nitze. "The winter 2017/2018 was extremely wet and warm. Conditions were similar to those our climate models predict will be normal by the end of this century. In a way, we caught a glimpse of the future. By then, widespread lake drainage will have reached a catastrophic scale."As Nitze and his co-authors report in the journal The For their study, Ingmar Nitze and his colleagues evaluated satellite images of the region surrounding Kotzebue and northwestern Alaska. In the pictures, the full and drained lakes can be easily distinguished. It is also clear when the lakes begin to drain. Winter 2017/2018 was the warmest in the region since continuous records began at the Kotzebue station in 1949. Accordingly, the experts had expected several lakes to drain. But they hadn't expected it to happen on this scale. "In the mild years 2005 and 2006, several lakes drained -- but this time there were twice as many." And that's worrying, the experts warn, because at the same time it means the permafrost's potential to preserve large amounts of carbon is shrinking at an alarming rate. | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130155832.htm | An escape route for seafloor methane | Methane, the main component of natural gas, is the cleanest-burning of all the fossil fuels, but when emitted into the atmosphere it is a much more potent greenhouse gas than carbon dioxide. By some estimates, seafloor methane contained in frozen formations along the continental margins may equal or exceed the total amount of coal, oil, and gas in all other reservoirs worldwide. Yet, the way methane escapes from these deep formations is poorly understood. | In particular, scientists have been faced with a puzzle. Observations at sites around the world have shown vigorous columns of methane gas bubbling up from these formations in some places, yet the high pressure and low temperature of these deep-sea environments should create a solid frozen layer that would be expected to act as a kind of capstone, preventing gas from escaping. So how does the gas get out?A new study helps explain how and why columns of the gas can stream out of these formations, known as methane hydrates. Using a combination of deep-sea observations, laboratory experiments, and computer modeling, researchers have found phenomena that explain and predict the way the gas breaks free from the icy grip of a frozen mix of water and methane. The findings are reported today in the journal Surprisingly, not only does the frozen hydrate formation fail to prevent methane gas from escaping into the ocean column, but in some cases it actually facilitates that escape.Early on, Fu saw photos and videos showing plumes of methane, taken from a NOAA research ship in the Gulf of Mexico, revealing the process of bubble formation right at the seafloor. It was clear that the bubbles themselves often formed with a frozen crust around them, and would float upward with their icy shells like tiny helium balloons.Later, Fu used sonar to detect similar bubble plumes from a research ship off the coast of Virginia. "This cruise alone detected thousands of these plumes," says Fu, who led the research project while a graduate student and postdoc at MIT. "We could follow these methane bubbles encrusted by hydrate shells into the water column," she says. "That's when we first knew that hydrate forming on these gas interfaces can be a very common occurrence."But exactly what was going on beneath the seafloor to trigger the release of these bubbles remained unknown. Through a series of lab experiments and simulations, the mechanisms at work gradually became apparent.Seismic studies of the subsurface of the seafloor in these vent regions show a series of relatively narrow conduits, or chimneys, through which the gas escapes. But the presence of chunks of gas hydrate from these same formations made it clear that the solid hydrate and the gaseous methane could co-exist, Fu explains. To simulate the conditions in the lab, the researchers used a small two-dimensional setup, sandwiching a gas bubble in a layer of water between two plates of glass under high pressure.As a gas tries to rise through the seafloor, Fu says, if it's forming a hydrate layer when it hits the cold seawater, that should block its progress: "It's running into a wall. So how would that wall not be preventing it from continuous migration?" Using the microfluidic experiments, they found a previously unknown phenomenon at work, which they dubbed crustal fingering.If the gas bubble starts to expand, "what we saw is that the expansion of the gas was able to create enough pressure to essentially rupture the hydrate shell. And it's almost like it's hatching out of its own shell," Fu says. But instead of each rupture freezing back over with the reforming hydrate, the hydrate formation takes place along the sides of the rising bubble, creating a kind of tube around the bubble as it moves upward. "It's almost like the gas bubble is able to chisel out its own path, and that path is walled by the hydrate solid," she says. This phenomenon they observed at small scale in the lab, their analysis suggests, is also what would also happen at much larger scale in the seafloor.That observation, she said, "was really the first time we've been aware of a phenomenon like this that could explain how hydrate formation will not inhibit gas flow, but rather in this case, it would facilitate it," by providing a conduit and directing the flow. Without that focusing, the flow of gas would be much more diffuse and spread out.As the crust of hydrate forms, it slows down the formation of more hydrate because it forms a barrier between the gas and the seawater. The methane below the barrier can therefore persist in its unfrozen, gaseous form for a long time. The combination of these two phenomena -- the focusing effect of the hydrate-walled channels and the segregation of the methane gas from the water by a hydrate layer -- "goes a long way toward explaining why you can have some of this vigorous venting, thanks to the hydrate formation, rather than being prevented by it," says Juanes.A better understanding of the process could help in predicting where and when such methane seeps will be found, and how changes in environmental conditions could affect the distribution and output of these seeps. While there have been suggestions that a warming climate could increase the rate of such venting, Fu says there is little evidence of that so far. She notes that temperatures at the depths where these formations occur -- 600 meters (1,900 feet) deep or more -- are expected to experience a smaller temperature increase than would be needed to trigger a widespread release of the frozen gas.Some researchers have suggested that these vast undersea methane formations might someday be harnessed for energy production. Though there would be great technical hurdles to such use, Juanes says, these findings might help in assessing the possibilities."The problem of how gas can move through the hydrate stability zone, where we would expect the gas to be immobilized by being converted to hydrate, and instead escape at the seafloor, is still not fully understood," says Hugh Daigle, an associate professor of petroleum and geosystems engineering at the University of Texas at Austin, who was not associated with this research. "This work presents a probable new mechanism that could plausibly allow this process to occur, and nicely integrates previous laboratory observations with modeling at a larger scale.""In a practical sense, the work here takes a phenomenon at a small scale and allows us to use it in a model that only considers larger scales, and will be very useful for implementing in future work," Daigle says. | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130150409.htm | The 'smell' of coral as an indicator of reef health | You might not normally think about what corals smell like -- or how the smell changes during heat stress. However, that is what researchers from the University of Technology Sydney (UTS), the University of Sydney and Southern Cross University set out to investigate on the Great Barrier Reef. | Every organism releases a distinct mix of volatile gases that makes up their smell and we are learning that these "smells" can tell us a lot about health. Some individual gases that make up the overall smell even have the ability to influence how an organism copes with stress, and once released from reefs, these gases can affect atmospheric processes.Despite their importance, these volatile gases have received little attention in tropical coral reefs. This study is the first to explore the overall "smell" of healthy and stressed corals, identifying a distinct chemical diversity.The research, led by Dr Caitlin Lawson in the Climate Change Cluster at UTS, discovered that across the coral species studied on Heron Island in the southern Great Barrier Reef, the abundance and chemical diversity of their gas emissions fell significantly during heat stress experiments. The findings are published in the journal Recent mass bleaching events, driven by heat stress, have largely caused a 50 per cent loss of Great Barrier Reef corals in the past 25 years. Climate forecasts suggest some Great Barrier Reef areas may bleach again in 2021."Our results provide the first insights into the range of gases produced by reef-building corals and highlight a diverse suite of compounds that may play potentially important -- but previously unrecognised -- roles in maintaining healthy reef functioning," Dr Lawson said."Our results also reveal that heat stress dramatically decreases the chemical diversity, quantity and functional potential of these important compounds, which could further impact the capacity of corals to cope with increasing temperatures."Co-author Dr Jean-Baptiste Raina said he was surprised to discover just how many different chemicals made up the "smell of these corals," when previously only a handful of compounds had been identified. He says that number is "just going to keep growing, the more we look into it and the more species we start to investigate."Further unlocking the complexity and diversity of these reef gases will allow scientists to understand just how they might be silently driving the health and resilience of deteriorating coral reefs, Dr Lawson said."We know that within terrestrial ecosystems, some of these compounds can help plants deal with drought conditions, for example, or heat stress or insect attack," she said."I get really excited about the signalling that could be happening between different species of corals, or whether they have certain smells that they'll release that might attract grazing fish if there's too much algae. Is there a certain smell that indicates corals are more vulnerable?"With the increasing frequency of heat stress events -- and it is looking likely that bleaching will occur again in early 2021 -- it is even more important that we understand coral emissions as they may prove to be a key tool in our efforts to monitor and conserve coral reefs."Senior author and leader of the Future Reefs Team at UTS, Associate Professor David Suggett says the discovery adds to the evidence that, just like humans, reefs rely on multiple forms of communication to stay healthy."Coral reef diversity is sustained through sights and sounds, and our work shows that smells also play many critical roles," he said."The discovery of a loss of these smells under heat stress driven by ocean warming is yet more evidence reefs will change as we know them unless we urgently tackle climate change." | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130131457.htm | Future Brahmaputra River flooding as climate changes may be underestimated, study says | A new study looking at seven centuries of water flow in south Asia's mighty Brahmaputra River suggests that scientists are underestimating the river's potential for catastrophic flooding as climate warms. The revelation comes from examinations of tree rings, which showed rainfall patterns going back centuries before instrumental and historical records. | Many researchers agree that warming climate will intensify the seasonal monsoon rains that drive the Brahmaputra, but the presumed baseline of previous natural variations in river flow rests mainly on discharge-gauge records dating only to the 1950s. The new study, based on the rings of ancient trees in and around the river's watershed, shows that the post-1950s period was actually one of the driest since the 1300s. The rings show that there have been much wetter periods in the past, driven by natural oscillations that took place over decades or centuries. The takeaway: destructive floods probably will come more frequently than scientists have thought, even minus any effects of human-driven climate change. Estimates probably fall short by nearly 40 percent, say the researchers. The findings were just published in the journal "The tree rings suggest that the long-term baseline conditions are much wetter than we thought," said Mukund Palat Rao, a PhD. student at Columbia University's Lamont-Doherty Earth Observatory and lead author of the study. "Whether you consider climate models or natural variability, the message is the same. We should be prepared for a higher frequency of flooding than we are currently predicting."The Brahmaputra is one of the world's mightiest rivers, flowing under a variety of names and braided routes some 2,900 miles through Tibet, northeast India and Bangladesh. Near its mouth, it combines with India's Ganga River to create the world's third largest ocean outflow, behind only the Amazon and the Congo. (It is tied with Venezuela's Orinoco.) At points, it is nearly 12 miles wide. Its delta alone is home to 130 million Bangladeshis, and many millions more live upstream.The river routinely floods surrounding areas during the July-September monsoon season, when moisture-laden winds sweep in from the Indian Ocean and bring rain along its length, from its Himalayan headwaters on down to the coastal plain. As with the Nile, the flooding has a good side, because the waters drop nutrient-rich sediment to replenish farmland, and some degree of flooding is essential for rice cultivation. But some years, the flooding runs out of control, and low-lying Bangladesh gets hit hardest. In 1998, 70 percent of the country went underwater, taking out crops, roads and buildings, and killing many people. Other serious floods came in 2007 and 2010. In September 2020 the worst flooding since 1998 was still underway, with a third of Bangladesh inundated, and 3 million people rendered homeless.Higher temperatures drive more evaporation of ocean waters, and in this region that water ends up as rainfall on land during the monsoon. As a result, most scientists think that warming climate will intensify the monsoon rains in coming decades, and in turn increase seasonal flooding. The question is, how much more often might big floods happen in the future?The authors of the new study first looked at records from a river-flow gauge in northern Bangladesh. This showed a median discharge some 41,000 cubic meters per second from 1956 to 1986, and 43,000 from 1987 to 2004. (In the big flood year of 1998, peak discharge more than doubled.)They then looked at data from the rings of ancient trees that researchers sampled at 28 sites in Tibet, Myanmar, Nepal and Bhutan, at sites within the Brahmaputra watershed, or close enough to be affected by the same weather systems. Most samples were taken from conifer species in the last 20 years by scientists from the Lamont-Doherty Tree Ring Lab, led by study coauthor Edward Cook. Since people have long been cutting down trees in populous areas, Cook and his colleagues sometimes hiked for weeks to reach undisturbed sites in remote, mountainous terrain. Straw-width samples were bored from trunks, without damage to the trees. The oldest tree they found, a Tibetan juniper, dated to the year 449.Back at the lab, they analyzed the tree rings, which grow wider in years when soil moisture is high, and thus indirectly reflect rainfall and resulting river runoff. This allowed the scientists to assemble a 696-year chronology, running from 1309 to 2004. By comparing the rings with modern instrumental records as well as historical records going back to the 1780s, they could see that the widest rings lined up neatly with known major flood years. This in turn allowed them to extrapolate yearly river discharge in the centuries preceding modern records. They found that 1956-1986 was in only the 13th percentile for river discharge, and 1987-2004 in the 22nd.This, they say, means that anyone using the modern discharge record to estimate future flood hazard would be underestimating the danger by 24 to 38 percent, based solely on natural variations; human driven warming would have to be added on top of that. "If the instruments say we should expect flooding toward the end of the century to come about every four and a half years, we are saying we should really expect flooding to come about every three years," said Rao.The tree rings do show some other relatively dry times, in the 1400s, 1600s and 1800s. But they also show very wet periods of extreme flooding with no analog in the relatively brief modern instrumental period. The worst lasted from about 1560-1600, 1750-1800 and 1830-1860.Climate change will almost certainly affect the flow of other major rivers in the region, though not necessarily in the same ways. The mighty Ganga, flowing mainly through India, is also powered mainly by the monsoon, so it will likely behave much like the Brahmaputra. But the Indus, which flows through Tibet, India and Pakistan, derives most of its flow not from the monsoon, but rather from the winter buildup of snow and ice in Himalayan glaciers, and subsequent melting in summer. In 2018 Rao and colleagues published a tree-ring study showing that the river's flow has been anomalously high in recent years. They suggest that as climate warms and the glaciers undergo accelerated melting, the Indus will supply plenty of needed irrigation water -- but at some point, when the glaciers lose enough mass, the seasonal spigot will turn the other way, and there may not be enough water.Human vulnerability to floods along the Brahmaputra has increased in recent years due not only to sheer water volume, but because population and infrastructure are growing fast. On the other hand, accurate flood warnings have become more advanced, and this has helped many villages reduce economic and social losses. "High discharges will continue to be associated with an increased likelihood of flood hazard in the future," write the study authors. But, they say, this could be counteracted to some extent by "potential changes in policy, land use, or infrastructure that may ameliorate flood risk."The study was also coauthored by Benjamin Cook, Rosanne D'Arrigo, Brendan Buckley and Daniel Bishop, all affiliated with the Lamont-Doherty Tree Ring Lab; Upmanu Lall of the Columbia Water Center; Columbia University ecologist Maria Uriarte; and collaborators at other U.S. universities and in Australia and China. | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130131404.htm | Emissions growth slower than worst-case projections | Under the worst-case scenarios laid out in the United Nations' climate change projections, global temperatures would increase more than 3.6 degrees Fahrenheit (2 degrees Celsius) by 2100, leading to at least 1.5 feet (0.5 meters) in global sea level rise and an array of disastrous consequences for people and planet. But new research from the University of Colorado Boulder finds that these high-emissions scenarios, used as baseline projections in the UN's Intergovernmental Panel on Climate Change (IPCC) global assessments, have not accurately reflected the slowing rate of growth in the global economy and we are unlikely to catch up to them anytime soon. | The new study, published today in The good news: Emissions are not growing nearly as fast as IPCC assessments have indicated, according to the study's authors. The bad news: The IPCC is not using the most accurate and up-to-date climate scenarios in its planning and policy recommendations."If we're making policy based on anticipating future possibilities, then we should be using the most realistic scenarios possible," said Matt Burgess, lead author on the study and a fellow at the Cooperative Institute for Research in Environmental Sciences (CIRES) at CU Boulder. "We'll have better policies as a result."The IPCC was established in 1988 and provides policymakers around the globe with regular research-based assessments on the current and projected impacts of climate change. Its reports, the sixth of which is due out in 2022, play an instrumental role in shaping global climate policy.To see if IPCC scenarios are on track, the researchers compared projections from the latest report, published in 2014, and data used to prepare the upcoming report, to data gathered from 2005 to 2017 on country-level gross domestic product (GDP), fossil-fuel carbon dioxide emissions, likely energy use and population trends during this century. Burgess and his co-authors show that even before the pandemic, due to slower-than-projected per-capita GDP growth, as well a declining global use of coal, these high-emissions scenarios were already well off-track in 2020, and look likely to continue to diverge from reality over the coming decades and beyond. The COVID-19 pandemic's dampening effect on the global economy only accentuates their findings, they said.As a result, they contend that these high-emissions scenarios should not be used as the baseline scenarios in global climate assessments, which aim to represent where the world is headed without additional climate mitigation policy.When it comes to climate change scenarios, some scientists and climate experts fear that economic growth will be higher than the projected scenarios, and we'll be taken by surprise by climate changes. But that is unlikely to happen, according to Burgess, assistant professor in environmental studies and faculty affiliate in economics.This new research adds to a growing literature that argues that economic growth and energy use are currently over-projected for this century. The research also points out that the high-emissions scenarios used by the IPCC don't fully account for economic damages from climate change.The researchers recommend that these policy-relevant scenarios should be frequently recalibrated to reflect economic crashes, technological discoveries, or other real-time changes in society and Earth's climate. Anticipating the future is difficult and updates are to be expected, according to Roger Pielke Jr., co-author on the paper and professor of environmental studies.Their study does not mean that people can let their guard down when it comes to addressing climate change, the authors stress. No matter the scenario, the only way to get to net zero emissions as a society is to dramatically reduce carbon dioxide emissions from our energy sources."We're still affecting the climate and the challenge of reducing emissions is as hard as ever," said Pielke Jr. "Just because it's not the worst-case scenario doesn't mean that the problem goes away."Additional co-authors on this paper include John Shapland in Environmental Studies at CU Boulder and Justin Ritchie of the University of British Columbia's Institute for Resources, Environment and Sustainability. | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130101243.htm | Jaguars robust to climate extremes but lack of food threatens species | A new QUT-led study has found wild jaguars in the Amazon can cope with climate extremes in the short-term, but numbers will rapidly decline if weather events increase in frequency, diminishing sources of food. | Distinguished Professor Kerrie Mengersen and Professor Kevin Burrage led a team of researchers in a world-first investigation of the big cat's chances of survival.The new research results have been published in The jaguar (Professor Mengersen said the Pacaya Semiria Reserve covers 20,800 km2 in the Loreto region of the Peruvian Amazon, comprised of mostly primary forest."Estimates of jaguar numbers are difficult to achieve because the big cats are cryptic by nature, are not always uniquely identifiable, and their habitat can be hostile to humans," Professor Mengersen said.The project drew on information gathered during a 2016 trip to the remote reserve, as well as a census study based on camera traps and scat analysis, jaguar ecology, and an elicitation study of Indigenous rangers in the Pacaya Samiria National Reserve.Six jaguar population scenarios were analysed mapping the jungle creature's solitary behaviour, mating, births of cubs at certain times of the year, competition, illegal hunting, death from starvation and availability of key prey.Professor Kevin Burrage cautioned the predicted results for the jaguars in the long-term were concerning."Our results imply that jaguars can cope with extreme drought and flood, but there is a very high probability that the population will crash if the conditions are repeated over short time periods. These scenarios are becoming more likely due to climate change," he said."The declines may be further exacerbated by hunting of both jaguars and their prey, as well as loss of habitat through deforestation."Professor Burrage said scenario 1 estimated the jaguar population at 600-700 assuming stable prey availability while scenario 6 was an extreme case with drought and flood occurring every other year."In this worst-case scenario, prey levels could not recover, and jaguar populations was predicted to drop to single digits in 30 years' time," Professor Burrage said. | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130113559.htm | How stable is the Antarctic ice sheet? | As temperatures rise due to climate change, the melting of polar ice sheets is accelerating. An international team of researchers led by geoscientist Dr Kim Jakob from Heidelberg University has now examined the dynamics of the East Antarctic Ice Sheet more closely. This is by far the largest ice mass on Earth and is assumed to be less sensitive to climate change than other ice sheets simply because of its size. The researchers analysed data that they had obtained from deep-sea sediments dating back approximately 2.5 million years. This enabled them to determine the factors responsible for the stability of the East Antarctic Ice Sheet. The findings indicate that the ice masses of East Antarctica could be much less stable in a constantly warming climate than previously thought. | "The melting of polar ice sheets leads to a rise in global sea level, which is becoming an ever greater threat to coastal areas," explains Dr Jakob from the Institute of Earth Sciences at Heidelberg University. To better understand past changes in the large ice masses of East Antarctica, her research team performed geochemical analyses on deep-sea sediments from the Atlantic Ocean. The sediments were obtained through the Integrated Ocean Drilling Program (IODP), an international consortium of scientists formed to explore the ocean floor.These analyses enabled the reconstruction of global sea-level change from approximately 2.8 to 2.4 million years ago, which in turn reflects variations in the total volume of ice. During this period, high atmospheric COFactors conventionally accepted to have promoted the growth and decay of polar ice sheets during the Earth's history are the intensity of solar radiation and the COThe findings of the study contribute to a better understanding of the dynamics of global ice sheets under elevated atmospheric COBesides scientists from Heidelberg University, researchers from Goethe University Frankfurt, the Max Planck Institute for Chemistry in Mainz and the University of Southampton (Great Britain) contributed to this study. The research was funded in the context of the IODP priority programme of the German Research Foundation. The findings were published in the journal | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130113553.htm | Genes unlock clues to the evolution and survival of the Great Barrier Reef | In a ground-breaking new study, scientists used innovative molecular techniques to explain how corals on the east coast of Australia survived previous tough conditions -- enabling the Great Barrier Reef to become the vast reef it is today. | "We sequenced the genomes of 150 individual colonies of the same species of corals and used this to find out which genes are important for survival in inshore reefs," said the study's lead author Dr Ira Cooke from James Cook University."Genomes are like a time capsule containing an enormous wealth of historical information," said co-author Professor David Miller from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE)."Generally, single genomes are really useful in coral studies, but hundreds of genomes for the same species are a goldmine of information," Prof Miller said.The team delved into the ancient history of reefs, back some one million years, to when inshore corals from Magnetic Island first diverged from their northern reef kin.The scientists mapped the rise and fall of these two coral populations on the Great Barrier Reef, tracking which genes rapidly evolved to endure changing conditions, while measuring the flow of genes between locations.They say the results are important for the current and future conservation of coral reefs.Dr Cooke and his team already knew corals on the inshore Great Barrier Reef were able to flourish despite a disruptive environment of high turbidity and highly variable salinity and temperature parameters. By looking at the variation between genomes the team discovered exactly how the corals achieved this feat.The survival strategies used by the reef's inshore corals include a set of genes that evolved rapidly during the past 10,000 years. This time period includes flooding after the last ice-age. Another strategy includes the assimilation of specialist strains of coral symbiotic algae. These were found in reefs with some of the toughest conditions -- often close to rivers."These two strategies deserve special attention in future studies, as possible keys to the survival of corals under similar conditions," Dr Cooke said."Losing these reefs is a future possibility as coral reefs currently experience unprecedented, drastic and rapid changes due to human influence," Prof Miller said."Coral reefs are threatened by climate change, over-fishing and pollution."In addressing the latter, Dr Cooke says it's highly important to care for water catchments and water quality."As high-quality genome assemblies are derived from a broader range of corals and their symbionts, this and related approaches will become key tools," the authors said."These bring us closer to understanding the interaction between past climate conditions and the evolution of corals and coral reefs." | Climate | 2,020 |
November 30, 2020 | https://www.sciencedaily.com/releases/2020/11/201130101309.htm | Which factors trigger leaf die-off in autumn? | Researchers at ETH Zurich have identified a self-regulating mechanism in European deciduous trees that limits their growing-season length: Trees that photosynthesise more in spring and summer lose their leaves earlier in autumn. | Leaves of temperate deciduous trees glow in all their yellow and red glory just before falling, signalling that autumn has come. This process, called leaf senescence, allows trees to prepare for the coming winter by suspending their growth and extracting nutrients from the foliage. In the trees' phenological cycle, leaf senescence marks the end of the productive period during which they absorb COGlobal warming has resulted in longer vegetation periods in recent years, with spring leaf emergence in European trees happening about two weeks earlier than 100 years ago and autumn senescence about six days later. It is generally expected that senescence will continue to be delayed in a warming climate, increasing the amount of carbon captured by these plants under climate change.However, researchers at ETH Zurich have now come to the opposite conclusion. In a study published in the journal "Accurate forecasts of the growing season of trees have previously been difficult, as the drivers of leaf senescence have not been well understood," says Constantin Zohner, study leader and senior scientist at ETH Zurich's Crowther Lab.Until now, scientists have generally assumed that, after the summer ends, the autumnal declines in temperature and day length are the main cues determining the timing of leaf senescence. Some studies additionally indicated that leaf emergence in spring has an effect on leaf death in autumn. "But because the importance of these mechanisms remained unclear, phenological models were at best only partly able to take such effects into account," says the biologist.Zohner suspected that the link between spring and autumn phenology can be explained by photosynthetic activity -- or more precisely, the phenomenon of carbon sink limitation. In this hypothesis, scarce soil nutrients such as nitrogen, among other things, limit the quantity of COThis role of photosynthesis in the control of leaf senescence has long been known for example in crops, but has never been tested in trees. This is what motivated ETH Zurich researchers to investigate the drivers of autumn phenology with a combined approach of field observations, laboratory tests and modelling.Long-term observations of six European deciduous tree species over the last six decades formed the basis of the study. Using this data, Zohner's team tested the relative influence of various factors on the timing of autumn senescence, including leaf emergence in spring, seasonal photosynthesis, COIn addition, the researchers also performed a set of experiments with saplings in climate chambers and outdoors. This enabled them to isolate the effects of temperature, daylight and COThe long-term observations revealed a strong effect of photosynthesis: in years with increased photosynthesis in spring and summer, leaf senescence began earlier, with each ten percent increase in photosynthetic activity advancing leaf senescence by eight days. The experiments supported these findings."Our analyses suggest that seasonal photosynthesis, autumn temperatures and day length are the key drivers of senescence," says lead author Deborah Zani in explaining the forces involved. "Several other factors, such as atmospheric COWarmer autumns under climate change therefore tend to postpone senescence. This effect, however, is counteracted by increasing photosynthesis in spring and summer through rising COZani and Zohner developed a new model of autumn phenology that takes all factors into account according to their relevant weight. This model enabled the researchers to predict the timing of autumn senescence over the last six decades with up to 42 percent more accuracy compared to previous models.The authors then used this model to generate updated forecasts of leaf senescence timing over the rest of the century and the results were quite unexpected. Until now it had been expected that senescence would occur two to three weeks later by the end of the century. "Our new model suggests the contrary: if photosynthesis continues to increase, leaves will senesce three to six days earlier than they do today" says Zani. "This means that the growing season will be extended by only 8 to 12 days by the end of the century, around two to three times less than we previously thought," Zani adds. She conducted the data analysis and modelling as part of her Master's thesis at the Crowther Lab.In their study, the researchers made use of data from the Pan European Phenology Project, evaluating a total of 434,000 phenological observations at 3,800 locations in central Europe between 1948 and 2015. Six representative species were studied: European horse chestnut, silver birch, European beech, European larch, English oak and rowan.The authors see their study as evidence that temperate forests have a limited capacity to absorb CO | Climate | 2,020 |
November 27, 2020 | https://www.sciencedaily.com/releases/2020/11/201127085407.htm | Irreversible hotter and drier climate over inner East Asia | Mongolia's semi-arid plateau may soon become as barren as parts of the American Southwest due to a "vicious cycle" of heatwaves -- that exacerbates soil drying, and ultimately produces more heatwaves -- according to an international group of climate scientists. | Writing in the journal According to the study's findings, the record high temperatures in the region are accelerated by soil drying, and together these changes are magnifying the decline of soil water. "The result," coauthor Deliang Chen at Sweden's University of Gothenburg said, "is more heatwaves, which means more soil water losses, which means more heatwaves -- and where this might end, we cannot say."When soil is wet, evaporation cools air at the surface. However, when soil no longer has any moisture, heat transfers directly to the air. In their paper, Abrupt shift to hotter and drier climate over inner East Asia beyond the tipping point, the authors state that in the past 260 years, only recent decades "show significant anticorrelation between heatwave frequency and soil moisture, alongside a radical decline in soil moisture fluctuation." The scientists note that a series of recent heatwaves in Europe and North America reveal the connection with near-surface air and soil moisture and suggest that "the semi-arid climate of this region has entered a new regime in which soil moisture no longer mitigates anomalously high air temperature."Already, lakes in the Mongolian Plateau have experienced rapid reductions. As of 2014, researchers from China had documented a 26 percent decrease in the number of lakes greater than one square kilometer in size, with even larger average reductions in size for the region's largest lakes."Now we are seeing that it isn't just large bodies of water that are disappearing," said corresponding author Jee-Hoon Jeong of Chonnam National University in South Korea. "The water in the soil is vanishing, too.""This may be devastating for the region's ecosystem which is critical for the large herbivores, like wild sheep, antelope and camels," Peng Zhang, the study's lead author and a researcher at the University of Gothenburg. "These amazing animals already live on the edge, and these impacts of climate change may push them over."Coauthor Jin-Ho Yoon, of the Gwangju Institute of Science and Technology in South Korea, noted that the hundreds of years of tree-ring data make it clear that the confluence of increased summer heatwaves and severe droughts are unique in the context of the past 260 years. Coauthor Hans Linderholm, from the University of Gothenburg, said the trees used in the analysis appear to "feel" the heatwaves throughout their lifetimes."The conifer trees respond strongly to anomalously high temperatures," Linderholm said. "By examining their growth rings, we can see their response to the recent heatwaves, and we can see that they do not appear to have experienced anything like this in their very long lives."Tree rings examined in the study were mainly collected from the Mongolian Plateau, which suggests that the increasing heat is affecting plants even at high elevations.Daniel Griffin, of the University of Minnesota's Department of Geography, Environment and Society, who is not involved in this study but has reviewed the paper, said that long-term perspective from these tree-ring records illustrates a nuanced picture of the changing climate that is now afflicting large swaths of the inner East Asia region."It is one thing to recognize that the "normal" climate conditions are changing. However, what concerns me the most is thinking about the extreme events of the future: how severe might those become?" asked Griffin. "And if the "new normal" is extremely hot and dry by historical standards, then future extremes may well be unlike anything previously witnessed."While warmer and drier trends are observed over Europe and Asia, Mongolia and its surrounding countries are particularly interesting to climate scientists because this Inner East Asia region has a very direct link to global atmospheric circulations."Summer atmospheric waves tend to create a high-pressure ridge pattern around Mongolia that can persist for weeks, triggering heatwaves," explained coauthor Simon Wang of Utah State University in the United States. "The warming climate is amplifying these atmospheric waves, increasing the chance of prolonged or intensified high-pressure to occur over Mongolia and this can also have ramifications across the Northern hemisphere.""Such large-scale atmospheric force is further amplified by local interactions with the land surface," coauthor Hyungjun Kim, from the University of Tokyo in Japan, pointed out. "An even worse problem may have already occurred in which an irreversible feedback loop is triggered and is accelerating the region toward a hotter and drier future."Indeed, the researchers have observed that recent heatwaves have come with even drier and hotter air, under the strengthened high-pressure ridge, than the heatwaves of the past.The research team found that the warming and drying concurrence seems to approach a "tipping point" and is potentially irreversible, which may push Mongolia into a permanent state of aridness. | Climate | 2,020 |
November 26, 2020 | https://www.sciencedaily.com/releases/2020/11/201126085919.htm | Satellite images confirm uneven impact of climate change | University of Copenhagen researchers have been following vegetation trends across the planet's driest areas using satellite imagery from recent decades. They have identified a troubling trend: Too little vegetation is sprouting up from rainwater in developing nations, whereas things are headed in the opposite direction in wealthier ones. As a result, the future could see food shortages and growing numbers of climate refugees. | More than 40 percent of Earth's ecosystems are arid, an amount that is expected to increase significantly over the course of the 21st century. Some of these areas, such as those in Africa and Australia may be savannah or desert, where sparse rainfall has long been the norm. Within these biomes, vegetation and wildlife have adapted to making use of their scant water resources, but they are also extraordinarily vulnerable to climate change.Using extensive imagery from satellites that monitor Earth every day, researchers from the University of Copenhagen's Department of Geosciences and Natural Resources Management have studied the evolution of vegetation in arid regions. Their conclusion is unequivocal:"We observe a clear trend of arid areas developing in a negative direction in the most economically challenged countries. Here, it is apparent that the growth of vegetation has become increasingly decoupled from the water resources available and that there is simply less vegetation in relation to the amount of rainfall. The opposite is the case in the wealthiest countries," explains Professor Rasmus Fensholt of the Department of Geosciences and Natural Resource Management.The researchers analyzed 15 years worth of satellite imagery of vegetation and rainfall -- from 2000 to 2015. To compare the evolution of vegetation in arid regions of the world, the researchers removed precipitation totals from the equation. In other words, they produced a calculation that accounts for the fact that some regions received more rain in past decades, while other regions received less.This provides a more accurate picture of ecosystem health, as human influences become easier to identify: In other words, whether resource use is balanced or whether an ecosystem's resources have been overexploited, with potentially fatal consequences -- as imbalanced systems may be irreparable."Here, our results demonstrate that in arid regions, particularly those in Africa and Asia, less vegetation grows for the amount of rainwater that falls, while more vegetation grows in arid areas of South America and Australia," says lead author Christin Abel, a postdoc at the Department of Geosciences and Natural Resource Management.Infographic text: Areas with purple hues indicate where vegetation growth relative to rainfall is declining, while green hues reveal areas where vegetation has grown more than expected. White areas represent ecosystems where vegetation growth is in balance with the water resources available.According to the researchers, there may be several explanations for why climate change and rising global temperatures are impacting vegetation in arid regions of the world's poorest countries. Among the most obvious is rapid population growth, in Africa for example, where there is an increasing need to exploit land that is otherwise poorly suited for agriculture. Doing so produces lower yields and puts increasing amounts of livestock on too little grass in already fragile ecosystems.Conversely, vegetation in arid areas of the world's wealthier countries seems to be coping better with climate change. This is likely due to the intensification and expansion of larger farms, where more economic resources allow for, among other things, irrigation and fertilization.As a result of climate change, future trends for the planet's poorest areas only seem to be getting worse. Forecasts point to an expansion of today's arid areas where they will make up a larger and larger share of our global ecosystems. This may result in more and more people being left without food and their needing to migrate."One consequence of declining vegetation in the world's poorer arid regions areas may be an increase in climate refugees from various African countries. According to what we've seen in this study, there is no indication that the problem will diminish in the future," explains Rasmus Fensholt.For a number of years, satellite imagery has let researchers observe that, overall, it actually appears that the world's arid regions have become greener. However, when researchers look at how much vegetation arid areas in developing countries get in relation to rainfall amounts, the picture looks different."We have been pleased to see that, for a number of years, vegetation has been on an upwards trend in arid regions. But if we dig only a tiny bit deeper and look at how successfully precipitation has translated into vegetation, then climate change seems to be hitting unevenly, which is troubling," says Rasmus Fensholt. | Climate | 2,020 |
November 25, 2020 | https://www.sciencedaily.com/releases/2020/11/201125114416.htm | Ice sheets on the move: How north and south poles connect | Over the past 40,000 years, ice sheets thousands of kilometres apart have influenced one another through sea level changes, according to research published today in | As the climate cooled, during the last Ice Age, water became locked up in land ice in the Northern Hemisphere leading to dropping sea levels in Antarctica and consequent growth of the ice sheet. As the climate warmed, on the other hand, as it did through the period of deglaciation, the retreating ice in the Northern Hemisphere led to rising water levels around Antarctica, which in turn drove a retreat of the Antarctic ice sheet."Ice sheets can influence each other over great distances due to the water that flows between them," explains senior author Natalya Gomez, from McGill's Department of Earth and Planetary Sciences. "It's as though they were talking to one another through sea level changes.""Polar ice sheets are not just large, static mounds of ice. They evolve on various different time scales and are in constant flux, with the ice growing and retreating depending on the climate and the surrounding water levels," explains Gomez. "They gain ice as snow piles up on top of them, then spread outwards under their own weight, and stream out into the surrounding ocean where their edges break off into icebergs."In order to investigate the mechanisms involved in driving changes in the Antarctic ice sheet over geologic time scales, the study draws on numerical modeling and a wide range of geological records, from cores of sediment from the ocean bottom near Antarctica to records of land exposure and past shorelines.With this information, the researchers were able, for the first time, to simulate, simultaneously, changes in both sea levels and ice dynamics in both hemispheres over the past 40,000 years. This time frame provides the basis for a broad understanding of how climate factors affect ice sheets, since it covers the period leading up to the peak of last Ice Age, between 26,000-20,000 years ago up to the present.The records suggest that there the ice loss from the Antarctic ice sheet over this period was significant, with intermittent periods of accelerated retreat. The researchers found that the only mechanism that could explain this response were the sea level changes in Antarctica caused by changes to the ice sheets in the Northern Hemisphere."We found a very variable signal of ice-mass loss over the last 20,000 years, left behind by icebergs breaking off Antarctica and melting down in the surrounding oceans," says Michael Weber, from the Department of Geochemistry and Petrology at the University of Bonn. "This evidence could hardly be reconciled with existing models until we accounted for how the ice sheets in both hemispheres interact with one another across the globe.""The scale and complexity of ice sheets and the oceans, and the secrets of the Earth's past climate that are locked up in the geological record are fascinating and inspiring," concludes Gomez. "Our results highlight how interconnected the Earth system is, with changes in one part of the planet driving changes in another. In the modern era, we haven't seen the kind of large ice sheet retreat that we might see in our future warming world. Looking to records and models of changes in Earth's history can inform us about this." | Climate | 2,020 |
November 25, 2020 | https://www.sciencedaily.com/releases/2020/11/201125091514.htm | In fire-prone West, plants need their pollinators -- and vice versa | 2020 is the worst fire year on record in the United States, with nearly 13 million acres burned, 14,000 structures destroyed and an estimated $3 billion spent on fire suppression -- and counting. At the same time, certain land managers have invested huge amounts of time and resources toward restoring fire through "controlled burn" approaches. | In the face of heartbreaking losses, effort and expense, scientists are still grappling with some of the most basic questions about how fire influences interactions between plants and animals in the natural world.A new study grounded in the northern Rockies explores the role of fire in the finely tuned dance between plants and their pollinators. Published Nov. 25 in the "A large number of studies have looked at how fire affects plants, or how fire affects animals. But what is largely understudied is the question of how fire affects both, and about how linkages within those ecological networks might respond to fire disturbance," said Jonathan Myers, associate professor of biology in Arts & Sciences at Washington University, a co-author of the study.The researchers discovered that wildfire disturbance and plant-pollinator interactions are both important in determining where plants take root and where pollinators are found. But in burned landscapes, plant-pollinator interactions are generally as important or more important than any other factor in determining the composition of species present.The importance of flowering-plant species in determining the composition of pollinator species doubled to quadrupled following wildfire. In addition, the importance of pollinators in determining plant composition nearly doubled following wildfire."Clearly, pollinators perform a valuable ecosystem service for humans by pollinating all our crops. In intact natural ecosystems, they perform an equally valuable service," said Joseph LaManna, assistant professor of biological sciences at Marquette University, first author of the study. "What we are seeing is that plant and pollinator linkages become even more important in disturbed or burned landscapes. These connections are important for restoring ecosystems in which natural wildfire regimes have been altered or suppressed by human activities."And as climate change increases the frequency and intensity of wildfires, the potential for biodiversity loss -- for losses of individual plant or pollinator species -- is going to be even more profound than we anticipated," he said.Wildfire in the northern Rockies can be ignited by lightning -- but more and more, it is started by people.Historically, wildfires tended to burn hot in some spots and cold in others, resulting in a patchwork or mosaic of differing levels of fire disturbance. But with rising global temperatures, the plant debris and other materials that fuel fires are drying out. That trend combined with decades of active fire suppression has resulted in a shift from a majority mixed-severity wildfire regime to today's high-severity blazes.For this study, co-author Laura Burkle at Montana State University led the field inventories of plants and pollinators at 152 plots in Montana representing a wildfire gradient including plots with no recent wildfire (unburned), mixed-severity wildfire and high-severity wildfire. LaManna and Myers worked with Burkle and Travis Belote of The Wilderness Society to analyze the data.At the sites they compared, the scientists found that the number of individual bees, flies and butterflies -- and the flowering plants they frequent -- were higher in parts of the landscape that had burned, as opposed to those that hadn't burned.However, increases were greater in areas that had experienced mixed-severity wildfire, which leaves some vegetation intact in a mosaic of habitat types, as opposed to high-severity wildfire, which largely removes all vegetation and can damage the soil and seed bank.For example, flowering-plant abundances increased more than 10-fold in mixed-severity wildfire and more than nine-fold in high-severity wildfire compared with unburned areas. Overall the researchers identified 329 pollinator species and 193 flowering-plant species."Oftentimes, the public perception about fire in general is that it is bad. But it was impressive how much higher the abundances of both plants and pollinators were -- as well as the number of species -- in the burned landscapes compared with the unburned landscapes," Myers said.Although this study shows that fire increased abundances and species diversity of pollinators and flowering plants overall, the intensity of the fire matters. Hotter, high-severity burns can eliminate landscape features that pollinators require, like stumps or woody debris for nesting. Mixed-severity wildfire is most beneficial.Around the world, pollinator populations are in decline. The northern Rockies are no exception to this troubling trend."Thanks to this project, we now have very in-depth knowledge of local pollinator communities, especially the bee communities," Burkle said. "One of the benefits of these data is to be able to provide expert knowledge about declining pollinator species and species of concern, like the Western Bumble Bee ("When we think about patterns of biodiversity across space, we typically consider different groups of species separately," she said. "In our case, we might consider patterns of plant diversity separately from patterns of pollinator diversity. But our study provides solid evidence that -- above and beyond the influence of disturbances like wildfires -- the relationships that plants have with pollinators are strong contributors to these patterns of biodiversity."This means that biotic interactions among species are important and will need to be considered more explicitly in conservation actions, like plans for species range shifts with climate change."Global climate change is likely to increase the frequency and intensity of wildfires in many other regions -- as it has in the mountain West, the researchers said.The findings from this study suggest that this could possibly result in additional losses of vulnerable species."We may see wildfire accelerating co-extinction events where you lose a pollinator and then you lose all of the plants that the pollinator depended on -- and then you lose more pollinators that were associated with those plants, and so on," LaManna said. "You have a potential for a chain of losses."Overall, this research advances understanding of how and why wildfire affects conservation, land management and restoration of forest ecosystems. It also shows that ecological models that predict how species will respond under various climate change scenarios also should consider biological interactions within food webs, Myers said."By sharing our findings with federal land managers across the region, we hope to contribute to management plans, with the dual aim of maintaining biodiversity of plants and pollinators while restoring environmental complexity representative of historical fire regimes," Myers said. | Climate | 2,020 |
November 24, 2020 | https://www.sciencedaily.com/releases/2020/11/201124150832.htm | Researchers go underwater to study how sponge species vanished | Researchers from Tel Aviv University (TAU) embarked on an underwater journey to solve a mystery: Why did sponges of the Agelas oroides species, which used to be common in the shallow waters along the Mediterranean coast of Israel, disappear? Today, the species can be found in Israel mainly in deep habitats that exist at a depth of 100 meters (330 feet). | The researchers believe that the main reason for the disappearance of the sponges was the rise in seawater temperatures during the summer months, which in the past 60 years have risen by about 3°C (37°F).The study was led by Professor Micha Ilan and PhD student Tal Idan of TAU's School of Zoology at the George S. Wise Faculty of Life Sciences and Steinhardt Museum of Natural History. The article was published in the journal "Sponges are marine animals of great importance to the ecosystem, and also to humans," Professor Idan explains. "They feed by filtering particles or obtain substances dissolved in the seawater and making them available to other animals. Sponges are also used as a habitat for many other organisms and contain a wide variety of natural materials used as a basis for the development of medicines."In our study, we focused on the Agelas oroides species, a common Mediterranean sponge that grew throughout the Mediterranean Sea from a depth of less than a meter to 150 meters deep. But the sponge has not been observed in Israel's shallow waters for over 50 years."During the study, the researchers used a research vessel and an underwater robot belonging to the nongovernmental organization EcoOcean. With that help, they located particularly rich rocky habitats on the seabed at a depth of about 100 meters (330 feet), approximately 16 kilometers (10 miles) west of Israeli shores. The most dominant animals in these habitats are sponges, which is why the habitats are called "sponge gardens."The researchers collected 20 specimens of the Agelas oroides sponge, 14 of which were transferred to shallow waters at a depth of 10 meters (about 30 feet), at a site where the sponge was commonly found in the 1960s. The remaining six specimens were returned to the sponge gardens from which they were taken and used as a control group.The findings showed that when the water temperature ranged from 18°-26°C (64°-79°F), usually in the months of March to May, the sponges grew and flourished: they pumped and filtered water, the action by which they feed, and their volume increased. But as the water temperature continued to rise, the sponges' condition deteriorated. At a temperature of 28°C (82°F), most of them stopped pumping water, and during the month of July, when the water temperature exceeded 29°C (84°F), all of the sponges that had been transferred to the shallow water died within a short period of time.At the same time, the sponges in the control group continued to enjoy a relatively stable and low temperature between 17°-20°C (63°-68°F), which allowed them to continue to grow and thrive.The researchers believe that the decisive factor that led to the disappearance of the sponges from the shallow area was prolonged exposure to high seawater temperature. According to them, "In the past, the temperature would also reach 28.5°C (83°F) in the summer, but only for a short period of about two weeks. So the sponges, even if damaged, managed to recover. Today, seawater temperatures rise above 29°C (84°F) degrees for three months, which likely causes multi-system damage in sponges and leaves them no chance of recovering and surviving.""From 1960 until today, the water temperature on the Israeli Mediterranean coast has risen by 3°C (37°F), which may greatly affect marine organisms, including sponges," Professor Ilan concludes. "Our great concern is that the changes taking place on our shores are a harbinger of what may take place in the future throughout the Mediterranean. Our findings suggest that continued climate change and the warming of seawater could fatally harm sponges and marine life in general." | Climate | 2,020 |
November 24, 2020 | https://www.sciencedaily.com/releases/2020/11/201124134618.htm | Strengthening the climate change scenario framework | Over the past decade, the climate change research community developed a scenario framework that combines alternative futures of climate and society to facilitate integrated research and consistent assessment to inform policy. An international team of researchers assessed how well this framework is working and what challenges it faces. | The scenario framework contains a set of scenarios about how society may evolve in the future -- so-called Shared Socioeconomic Pathways (SSPs) -- and defines different levels of climate change known as Representative Concentration Pathways (RCPs). Combining both aspects of the framework allows researchers to develop integrated analyses of how future societies can avoid climate change and cope with its impacts."The SSPs started with brief global narratives combined with projections of a few key variables like GDP, population, and urbanization. In the past few years, researchers extended the SSPs to individual countries, cities, and sectors. They've also added new indicators, such as governance, income distribution, access to basic services, and air pollution. The framework has been widely and successfully applied, and has shaped climate change research," explains Brian O'Neill, director of the Joint Global Change Research Institute (JGCRI) and main author of the assessment published in "The scenarios framework allows scientists to use similar scenarios across many different studies. Individual research projects don't need to develop their own scenario storylines and quantifications but can build on the work of others. Once many studies use comparable scenarios, it becomes more straightforward to assess the literature for insights that emerge across these studies. This means that large scientific assessments like the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) can use the framework to structure their analyses and reports," adds IIASA researcher Bas van Ruijven, one of the authors of the study and co-chair of the International Committee on New Integrated Climate Change Assessment Scenarios (ICONICS).In their paper, the authors synthesize the insights from the first ever Scenarios Forum organized by the University of Denver and ICONICS in Denver, CO in March 2019, and present the first in-depth literature analysis of the SSP-RCP scenarios framework. They specifically looked into how useful the framework has been for researchers, which topics the SSPs have been used for, and what can be done to improve the framework and make it more useful for future studies.The results show that the framework has been used in almost 1,400 studies over the past five years, of which about half are related to climate impacts, one-third to avoiding climate change, and the remainder to extensions or methodological improvements. Encouragingly, the findings indicate that the scenarios framework enables research that had not been possible before, such as estimating the combined impacts of socioeconomic and climate changes on exposure to climate risks. The insights from this new study will help researchers to improve the framework and make it even more useful over the next five years. The study also revealed that some studies use unlikely combinations of socioeconomic assumptions with the highest climate change outcomes (the so-called RCP8.5 pathway). They caution that researchers should be more careful using this high climate change scenario for their studies in combination with a development pathway aiming to sustainable development, as well as in communication about their findings.The authors identified seven recommendations for future work:"While the scenarios framework is mostly used by researchers, it has also been translated into accessible non-technical language for the public. It has had a significant impact on how we study and think about future climate change. By identifying the weaknesses of the existing framework, we improve the utility of the framework for future studies. Also, by combining socioeconomic and climate change scenarios with other societal objectives (e.g., biodiversity), we can paint a more concrete picture of what future societies might look like and systematically explore how to avoid climate change and how to cope with its impacts," notes IIASA Energy Program Director Keywan Riahi, who was also a study author.Going forward, ICONICS and IIASA will support the research community in further improving the scenarios framework. To facilitate these developments, the two organizations will organize an online seminar and discussion series starting in January 2021. To foster and track progress, and revise goals as experience accumulates, the Scenarios Forum is intended to become a regular biennial event. To this end, IIASA and the ICONICS Steering Committee plan to host the second Scenarios Forum in Laxenburg, Austria in 2022. | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123161045.htm | Nature is widely adapted to current climate -- making it harder to adjust to a new one | To do the right thing at the right time, organisms need to glean cues from their environment. With ongoing climate change, the timing of these cues, like the accumulation of warm days, is rapidly shifting. Now a network of researchers working on an unprecedentedly large dataset of seasonal events has shown that the timing of species' activity fail to keep up with their cues, and that how quickly activity shifts reflects past evolution. | The observed patterns of local adaptation translate to a massive imprint on nature's calendar, making geographic variation in the timing of natural events more pronounced in spring and less pronounced in autumn. Since organisms have evolved to respond differently in different areas, it will take further evolution to adjust to the new climate.In nature, species' activities are timed to their environment. For plants to bloom when their pollinators are around, for birds to breed when there is food for their chicks -- and then to leave before snow covers the ground -- they must follow cues in their environment."One such cue relates to temperatures: in warm years, all types of events tend to occur early, and in cold years, they tend to occur late. How much events shift with shifts in temperature is described by something that we call a "reaction norm"," explains Professor Tomas Roslin, one of the lead authors of the study, who runs twin research teams at both the University of Helsinki and in Uppsala, at the Swedish University of Agricultural Sciences.Since keeping track of the seasons is so important, it can be subject to selection in nature. As a result, species' reaction norms can be adapted to their local environment. With a given shift in the cue, individuals in one place may shift the timing of their activity more than in another. Now, what happens when the local environment changes -- as it is now doing across the world?To answer this question, researchers have compiled meticulously collected observations of hundreds of seasonal phenomena made over decades at several hundred sites throughout the former Soviet Union. This massive data set has opened an unprecedented opportunity to explore climate change responses over an enormous area and over an enormous time scale."We looked at events ranging from the first song of the great tit through the appearance of the common toad and the appearance of the first porcini mushroom to the end of birch leaf fall," says Maria Delgado, the other lead author of the study, from the Oviedo University in Spain. "What we saw was a general rigidity in species' response to year-to-year variation in climate, i.e. the earlier the year, the more did the timing of the phenological event lag behind the timing of the cue from temperatures.""On top of this, we saw large differences between seasons and sites. Differences in the reaction norms of different sites accentuated phenological responses in the spring and dampened them in the autumn. As a result, among population variation in the timing of events is greater in the spring and less in the autumn than if all populations followed the same reaction norm. Overall, such patterns will affect species' response to climate change in opposite ways in spring and autumn."The data forming the basis of the study is quite the story, since they build on a previously uncovered archive of nature's calendar. For many decades -- in some cases a full century -- scientists have been recording events in more than 150 protected areas across the former Soviet Union. These data were meticulously compiled as an annual report, one for each protected area. For the longest time, this unique scientific contribution then laid hidden in the archives."But over the past decade, we have now been trying to mobilize these data. To this end, we have been working with an amazing group of more than 300 colleagues in over 80 organizations from Russia, Ukraine, Belarus, Kyrgyzstan, and Uzbekistan," explains Evgeniy Meyke, who together with Otso Ovaskainen coordinated the data basing of the enormous material from the University of Helsinki.Now compiled, The Chronicles of Nature program provides an archive exceptional in almost every aspect: It is comprehensive in nature, and spans over all sorts of species and events, long time periods (almost a century), large areas (half of Asia), and it has been systematically collected by dedicated, full time scientific staff. Many to the participating scientists have spent their entire life in collecting these data, and at the time of publication, six were already deceased. The current paper is thus a homage to their work."This has been a thrilling journey -- and it is only a beginning. We are excited by the enthusiasm of the environmental science professionals who initiated this collaboration. They gave the world an opportunity to connect with the results of their life long work, which had remained mostly unknown to the international scientific community," says Otso Ovaskainen, Professor of mathematical ecology at the University of Helsinki, and the primus motor behind the project. "Sadly, in most of the participating countries, protected areas and their staff are currently facing tough challenges. We hope that our findings will summon the interest of the international community, and focus attention on the global importance of these areas and the irreplaceable scientific work done by their staff. Should these time series break, there is no way to re-forge them." | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123161043.htm | A rich source of nutrients under the Earth's ice sheets | Trace elements such as iron, manganese and zinc are an integral part of the biogeochemical processes on the Earth's surface. As micronutrients, they play an essential role for the growth of all kinds of organisms and thus the Earth's carbon cycle. Below ice sheets, which cover around ten percent of the Earth's land surface, larger quantities of these substances are mobilised than previously assumed. This is shown by new data from Greenland and Antarctica, which were collected and analysed by an international research team led by Jon Hawkings from the GFZ German Research Centre for Geosciences in Potsdam and Florida State University (USA). They provide important insights into previously unknown processes at the boundary of ice, meltwater and rock. Because the ice masses are significantly influenced by global warming, new perspectives are emerging on the consequences climate change has for critical biogeochemical processes, including those in surrounding ecosystems such as oceans, lakes and wetlands. The study is published today in the journal | Under the Earth's ice sheets melt water forms an extensive hidden wetland of rivulets, rivers and lakes. During the last forty years, over 400 subglacial lakes have been discovered in Antarctica alone; some as large as the Great Lakes of North America. At the boundary between ice, water and rock, a complex ensemble of chemical, physical and microbiological forces is at work, breaking up and grinding rock and releasing trace elements into the meltwater which is carried downstream. These chemical elements occur only in very low concentrations, hence the name. Nevertheless they are -- like vitamins -- essential as nutrients for all living things.How and in which quantities trace elements are released under the Greenland and Antarctic ice sheets and eventually flow into the adjacent ecosystems, and what role they play in these ecosystems and the global carbon cycle at large, has not yet been studied in detail. This is because measurement campaigns in these remote regions of the world are an enormous logistical and technical challenge.In order to collect samples from the waters under the Greenland and Antarctic ice sheets and analyse them in the laboratory, Jon Hawkings from GFZ collaborated with an international and interdisciplinary research team. Colleagues Mark Skidmore and John Priscu from Montana State University (USA) led a project to drill more than 1000 metres into the Antarctic ice sheet as part of their SALSA project. This enabled them to tap into the nine-kilometre long and 15-metre deep Mercer Subglacial Lake. "There's a science reason for looking at that specific lake, but then there is the context of these lakes being part of this greater hydrological system," Mark Skidmore said. "So, we want to see what's being generated beneath the ice sheet and how that connects to the coastal environments."Jon Hawkings himself and colleagues under the lead of Jemma Wadham of the University of Bristol (UK) took samples from sub-ice waters emerging from Leverett Glacier in Greenland over a three-month period in the summer melt season.The samples were analysed in ultra-clean laboratories to avoid contamination. The researchers filtered the meltwater samples to multiple levels to sort the sample concentrations by size, as many of these trace elements can exist as extremely small nanoparticulate minerals. They determined their chemical composition using particularly sensitive mass-spectrometry methods.Hawkings and his colleagues discovered that significant amounts of trace elements are released in the melt waters below the ice masses. They found these melt water concentrations can exceed those in rivers and the open ocean by many times. For example, the value for dissolved iron in the Antarctic subglacial lake was more than 1000 micrograms per litre and not around five, as would be expected in dilute ice melt."For a long time it was assumed that in the icy regions of the earth trace elements are present in such miniscule quantities that they are of little importance for global elemental cycles. On the contrary, our results show that ice sheets may play a key role in regional mobilization of these elements. The impacts of this need to be further monitored and analysed in the context of climate change. We have now laid a baseline for this," says Jon Hawkings.Furthermore, the concentrations of the individual elements as well as their ratios and the size distribution between dissolved and nanoparticulate mineral forms tell the researchers something about the source material, the sub-ice sheet weathering processes and the paths taken by the water before sampling. For example, it is known that the element vanadium occurs primarily in silicate rock minerals rather than carbonate rock minerals. Elevated concentrations found in this study indicate that higher rates of silicate mineral weathering are occurring under ice sheets than previously thought. Importantly, silicate mineral weathering is a sink for carbon dioxide. Iron, on the other hand, is known to oxidise in an oxygen-rich environment, resulting in precipitated "rust." Large quantities of dissolved iron therefore indicate that some of the water may originate from a region with little oxygen. The researchers also found trace elements like aluminium, iron and titanium occurred in higher concentrations in Antarctica than in Greenland. They therefore hypothesise that the meltwater in the southern polar region has much longer residence times under the ice sheet and greater hydrological isolation than in the northern polar region.The new findings are particularly relevant for our understanding of nutrient cycling in the Southern Ocean. There the water is considered to be rich in nutrients like nitrogen and phosphorus but depleted in iron. For this reason, phytoplankton, the plants of the ocean, the base of the global food pyramid and an important CO2 sink, do not grow to their maximum potential. This "iron limitation" has been the subject of previous geoengineering projects to sequester carbon dioxide from the atmosphere by seeding the ocean with iron. The results of Hawkings and his colleagues are consistent with observations of higher quantities of iron and phytoplankton in the immediate vicinity of the Antarctic Ice Sheet. Their results suggest that the ice sheet may naturally fertilize the coastal regions of the Southern Ocean by providing a supply of iron for phytoplankton. To what degree and how this might change in the future with climatic warming remain open questions for further research.Hawkings and his collaborators investigated 17 different trace elements. "Each of these tells us its own story and we work like detectives, trying to make a coherent overall narrative out of all the data," says the geoscientist. "We are interested in exploring the limits of life on Earth in terms of the availability of energy and nutrients, and this helps tell us part of that story. We are only just beginning to understand the importance of these large ice masses in this context. Hopefully our research also helps in starting to answer many important outstanding scientific questions, which include the influence of climate change: How will these biogeochemical cycles change if more ice melts? Will this release more and more trace elements or will these processes be slowed down? In addition, it is still open what happens to the substances on their way into the oceans and how much ultimately reaches marine organisms."Collaborator and SALSA project lead John Priscu points out the importance of interdisciplinary work for scientific discoveries: "This paper intersects many disciplines and shows the power of international collaboration. Results in this manuscript have transformed our view of how polar ice sheets influence the Earth System." | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123161032.htm | Global warming likely to increase disease risk for animals worldwide | Changes in climate can increase infectious disease risk in animals, researchers found -- with the possibility that these diseases could spread to humans, they warn. | The study, conducted by scientists at the University of Notre Dame, University of South Florida and University of Wisconsin-Madison, supports a phenomenon known as "thermal mismatch hypothesis," which is the idea that the greatest risk for infectious disease in cold climate-adapted animals -- such as polar bears -- occurs as temperatures rise, while the risk for animals living in warmer climates occurs as temperatures fall.The hypothesis proposes that smaller organisms like pathogens function across a wider range of temperatures than larger organisms, such as hosts or animals."Understanding how the spread, severity and distribution of animal infectious diseases could change in the future has reached a new level of importance as a result of the global pandemic caused by SARS-CoV-2, a pathogen which appears to have originated from wildlife," said Jason Rohr, co-author of the paper published in The research team collected data from more than 7,000 surveys of different animal host-parasite systems across all seven continents to provide a diverse representation of animals and their pathogens in both aquatic and terrestrial environments. The study showed that pathogens found at warm locations outperform their animal hosts during cool weather as warm-adapted animals perform poorly. Similarly, pathogens found at cool locations thrive at warm temperatures, while cold-adapted animals are less tolerant of the heat.Researchers also collected historical temperature and precipitation records at the time and location of each survey, and long-term climate data for each location to understand how temperature affected animal disease risk in different climates, and how these patterns varied depending on traits of animals and pathogens. The study also revealed that cold-blooded animals tended to offer stronger support for the thermal mismatch hypothesis than warm-blooded animals.Next, they coupled their models to global climate change projections to predict where the risk of animal infectious diseases might change the most. The analysis suggests that global warming will likely shift infectious disease away from the equator, with decreases of animal infectious diseases in the lowland tropics and increases in the highland tropics, temperate and cooler regions of the planet."When each pathogen species was given equal weight, the predicted increases in infectious disease at cooler locations outweighed the decreases at warmer locations, potentially suggesting a net increase in animal infectious diseases with climate change," said Rohr, who is also an affiliated member of the Notre Dame Environmental Change Initiative and the Eck Institute for Global Health.As for next steps, Rohr says the researchers aim to evaluate whether similar patterns exist for human and plant diseases, the latter of which could have implications for food security.Co-authors on the study are Erin Sauer of South Florida and Wisconsin-Madison, and Olivia Santiago and Samuel Spencer of South Florida. The study was funded by the National Science Foundation and the National Institutes of Health. | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123161029.htm | Flow physics could help forecasters predict extreme events | About 1,000 tornadoes strike the United States each year, causing billions of dollars in damage and killing about 60 people on average. Tracking data show that they're becoming increasingly common in the southeast, and less frequent in "Tornado Alley," which stretches across the Great Plains. Scientists lack a clear understanding of how tornadoes form, but a more urgent challenge is to develop more accurate prediction and warning systems. It requires a fine balance: Without warnings, people can't shelter, but if they experience too many false alarms, they'll become inured. | One way to improve tornado prediction tools might be to listen better, according to mechanical engineer Brian Elbing at Oklahoma State University in Stillwater, in the heart of Tornado Alley. He doesn't mean any sounds audible to human ears, though. As long ago as the 1960s, researchers reported evidence that tornadoes emit signature sounds at frequencies that fall outside the range of human hearing. People can hear down to about 20 Hertz -- which sounds like a low rumble -- but a tornado's song likely falls somewhere between 1 and 10 Hertz.Brandon White, a graduate student in Elbing's lab, discussed their recent analyses of the infrasound signature of tornadoes at the 73rd Annual Meeting of the American Physical Society's Division of Fluid Dynamics.Elbing said these infrasound signatures had seemed like a promising avenue of research, at least until radar emerged as a frontrunner technology for warning systems. Acoustic-based approaches took a back seat for decades. "Now we've made a lot of advances with radar systems and monitoring, but there are still limitations. Radar requires line of sight measurements." But line of sight can be tricky in hilly places like the Southeast, where the majority of tornado deaths occur.Maybe it's time to revisit those acoustic approaches, said Elbing. In 2017, his research group recorded infrasound bursts from a supercell that produced a small tornado near Perkins, Oklahoma. When they analyzed the data, they found that the vibrations began before the tornado formed.Researchers still know little about the fluid dynamics of tornadoes. "To date there have been eight trusted measurements of pressure inside a tornado, and no classical theory predicts them," said Elbing. He doesn't know how the sound is produced, either, but knowing the cause isn't required for an alarm system. The idea of an acoustics-based system is straightforward."If I dropped a glass behind you and it shattered, you don't need to turn around to know what happened," said Elbing. "That sound gives you a good sense of your immediate environment." Infrasound vibrations can travel over long distances quickly, and through different media. "We could detect tornadoes from 100 miles away."Members of Elbing's research group also described a sensor array for detecting tornadoes via acoustics and presented findings from studies on how infrasound vibrations travel through the atmosphere. The work on infrasound tornado signatures was supported by a grant from NOAA.Other sessions during the Division of Fluid Dynamics meeting similarly addressed ways to study and predict extreme events. During a session on nonlinear dynamics, MIT engineer Qiqi Wang revisited the butterfly effect, a well-known phenomena in fluid dynamics that asks whether a butterfly flapping its wings in Brazil could trigger a tornado in Texas.What's unclear is whether the butterfly wings can lead to changes in the longtime statistics of the climate. By investigating the question computationally in small chaotic systems, he found that small perturbations can, indeed, effect long-term changes, a finding that suggests even small efforts can lead to lasting changes in the climate of a system.During the same session, mechanical engineer Antoine Blanchard, a postdoctoral researcher at MIT, introduced a smart sampling algorithm designed to help quantify and predict extreme events -- like extreme storms or cyclones, for example. Extreme events occur with low probability, he said, and therefore require large amounts of data, which can be expensive to generate, computationally or experimentally. Blanchard, whose background is in fluid dynamics, wanted to find a way to identify outliers more economically. "We're trying to identify those dangerous states using as few simulations as possible."The algorithm he designed is a kind of black box: Any dynamical state can be fed as an input, and the algorithm will return a measure of the dangerousness of that state."We're trying to find the doors to danger. If you open that particular door, will the system remain quiescent, or will it go crazy?" asked Blanchard. "What are the states and conditions -- like weather conditions, for example -- that if you were to evolve them over time could cause a cyclone or storm?"Blanchard said he's still refining the algorithm but hopes to start applying it to real data and large-scale experiments soon. He also said it may have implications beyond the weather, in any system that produces extreme events. "It's a very general algorithm." | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123112457.htm | Climate change presents new challenges for the drinking water supply | The Rappbode Reservoir in the Harz region is Germany's largest drinking water reservoir, supplying around one million people with drinking water in areas including the Halle region and the southern part of the state of Saxony-Anhalt. Water temperatures in the reservoir now have the potential to increase significantly due to climate change. If average global warming reaches between 4 and 6 degrees by the year 2100, as the current trend suggests, temperature conditions in the Rappbode Reservoir will become comparable to those in Lake Garda and other lakes south of the Alps. In an article in | The impacts of climate change can already be seen in the Rappbode Reservoir: Over the past 40 years, the water surface temperature in the reservoir has increased by around 4 degrees in the summer months. This trend could continue, as has now been demonstrated by a team of researchers led by Dr Karsten Rinke, who researches lakes at UFZ. Working on the basis of a lake model developed by US researchers, the team took into account potential reservoir management strategies to forecast the impacts climate change could have on water temperatures and on the lake's physical structure, which control the stratification and seasonal mixing of the body of water. Their research looked at three scenarios for future greenhouse gas emissions. The so-called "representative concentration pathways" (RCPs) describe whether greenhouse gas emissions will be halted (RCP 2.6), will continue to rise (RCP 6.0) or even continue to increase unabated (RCP 8.5) by 2100. According to the Intergovernmental Panel on Climate Change IPCC, the latter case would result in average global warming of more than 4 degrees by the end of this century.For the RCP 2.6 and RCP 6.0 scenarios, the study's authors projected that the average temperature on the water surface of the Rappbode Reservoir is set to increase by 0.09 degrees or 0.32 degrees respectively every decade by the year 2100. This would correspond to a total increase of around 0.7 degrees (RCP 2.6) and around 2.6 degrees (RCP 6.0) by the end of this century. As expected, the increase in temperatures would be the highest under the RCP 8.5 scenario, which would see the water temperature increasing by 0.5 degrees every decade or approx. 4 degrees by 2100.However, in terms of using drinking water, what happens in the deeper strata of the reservoir -- i.e., at depths of 50 metres and below -- is more serious, as this is where raw water is taken out before being treated to prepare it as drinking water. It is true that impacts by 2100 would be relatively minor under the RCP 2.6 and RCP 6.0 scenarios, as the water temperature would continue to be around 5 degrees year-round. However, water temperatures will increase significantly under the RCP 8.5 scenario -- by nearly 3 degrees by the end of the century. As a result, the water in the depths of the reservoir would warm to around 8 degrees. "This would turn a reservoir in Germany's northernmost highlands into a body of water comparable to Lake Maggiore or Lake Garda nowadays," says UFZ scientist Rinke. An increase of this magnitude would have consequences because it would significantly accelerate the speed of biological metabolic processes. "A temperature increase to 8 degrees nearly doubles oxygen demand, that is the amount of oxygen organisms consume during their respiration and degradation processes," says lead author Chenxi Mi, who is focusing on climate impacts on the Rappbode Reservoir in his doctorate at UFZ. Increased oxygen consumption will place an additional pressure on the water's oxygen budget, because the duration of summer stagnation -- the phase of stable temperature stratification in lakes in which the deep water is closed off to oxygen supply from the atmosphere -- is already extending due to climate change. Plus, warmer water is also unable to absorb as much oxygen. Potential consequences include intensified dissolution of nutrients and dissolved metals from the sediment, algae growth and an increase in blue-green algae.In other words, the 8.5 scenario would have impacts on the drinking water supply if it were to occur. The reservoir's operators draw the raw water from the lowermost strata for good reason, as the water there is cold and contains only low levels of suspended substances, dissolved metals, algae, bacteria and potentially pathogenic microorganisms. If the oxygen content there decreases more rapidly due to the rising water temperature, the risk of contamination increases, for example due to substances released from the sediment and greater bacteria growth. Treating the water would therefore require a greater effort on the part of the operators, and they would have to deal with higher demands in terms of the treatment capacity they would need to reserve. "This means preventing the deep water from warming is also worthwhile from the perspective of the drinking water supply, and the ideal way to do this is ambitious climate policies that limit warming," says Rinke.But the operators are not completely powerless against the warming of the deep water in the reservoir. The model simulations set up by Rinke's team show that a share of the heat can be exported by using a clever system to withdraw the water. This has to do with the water that is released to the downstream waters that is, the water that is withdrawn and drains into the water course below the reservoir in order to keep the discharge conditions there stable. This so-called downstream discharge would need to be withdrawn not from the lower strata as it has been thus far but rather from near the surface. "This approach would allow the additional heat caused by climate change to be released again," Rinke explains. However, he adds, it would be impossible to prevent the deep water from heating up if the air temperature increases beyond 6 degrees. "Even though operators have had to cope more with a shortage of water due to the very dry years we've had recently, it's just as important to think about the quality of the water. In terms of reservoir management, we definitely have options and can respond to new conditions caused by climate change. In this way, we can alleviate certain negative impacts through climate adaptation measures."The operators of the Rappbode Reservoir at the Talsperrenbetrieb Sachsen-Anhalt company are aware of this. They have been working closely together with Karsten Rinke and his team of researchers at UFZ for many years to assess the impacts of climate change and discussed about potential options for adapting the Rappbode Reservoir. The Talsperrenbetrieb is already planning new infrastructures that will make it possible to implement the new management strategies. | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123112439.htm | Scientists organize to tackle crisis of coral bleaching | An international consortium of scientists has created the first-ever common framework for increasing comparability of research findings on coral bleaching. | "Coral bleaching is a major crisis and we have to find a way to move the science forward faster," said Andréa Grottoli, a professor of earth sciences at The Ohio State University and lead author of a paper on guidelines published TBD in the journal The common framework covers a broad range of variables that scientists generally monitor in their experiments, including temperature, water flow, light and others. It does not dictate what levels of each should be present during an experiment into the causes of coral bleaching; rather, it offers a common framework for increasing comparability of reported variables."Our goal was to create a structure that would allow researchers to anchor their studies, so we would have a common language and common reference points for comparing among studies," said Grottoli, who also is director of the consortium that developed the common framework.Coral bleaching is a significant problem for the world's ocean ecosystems: When coral becomes bleached, it loses the algae that live inside it, turning it white. Coral can survive a bleaching but being bleached puts coral at higher risk for disease and death. And that can be catastrophic: Coral protects coastlines from erosion, offers a boost to tourism in coastal regions, and is an essential habitat to more than 25% of the world's marine species.Bleaching events have been happening with greater frequency and in greater numbers as the world's atmosphere -- and oceans -- have warmed because of climate change."Reefs are in crisis," Grottoli said. "And as scientists, we have a responsibility to do our jobs as quickly, cost-effectively, professionally and as well as we can. The proposed common framework is one mechanism for enhancing that."The consortium leading this effort is the Coral Bleaching Research Coordination Network, an international group of coral researchers. Twenty-seven scientists from the network, representing 21 institutions around the world, worked together as part of a workshop at Ohio State in May 2019 to develop the common framework.The goal, Grottoli said, is to allow scientists to compare their work, make the most of the coral samples they collect, and find ways to create a common framework for coral experimentation.Their recommendations include guidelines for experiments that help scientists understand what happens when coral is exposed to changes in light or temperature over a short period of time, a moderate period, and long periods. The guidelines include a compendium of the most common methods used for recording and reporting physical and biological parameters in a coral bleaching experiment.That such a framework hasn't already been established is not surprising: The scientific field that seeks to understand the causes of and solutions for coral bleaching is relatively young. The first reported bleaching occurred in 1971 in Hawaii; the first wide-spread bleaching event was reported in Panama and was connected with the 1982-83 El Niño.But experiments to understand coral bleaching didn't really start in earnest until the 1990s -- and a companion paper by many of the same authors found that two-thirds of the scientific papers about coral bleaching have been published in the last 10 years.Researchers are still trying to understand why some coral species seem to be more vulnerable to bleaching than others, Grottoli said, and setting up experiments with consistency will help the science move forward more quickly and economically."Adopting a common framework for experiments around coral bleaching would make us more efficient as a discipline," Grottoli said."We'd be able to better collaborate, and to build on one another's work more easily. It would help us progress in our understanding of coral bleaching -- and because of climate change and the vulnerability of the coral, we need to progress more quickly."Other Ohio State researchers who are co-authors on the paper are graduate students Rowan McLachlan, James T. Price and Kerri L. Dobson.This work was funded by the National Science Foundation. | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123101000.htm | Changes in fire activity are threatening more than 4,400 species globally | Changes in fire activity are putting at risk more than 4,400 species across the globe, says a new paper led by the University of Melbourne, involving 27 international researchers. | "Those species include 19 per cent of birds, 16 per cent of mammals, 17 per cent of dragonflies and 19 per cent of legumes that are classified as critically endangered, endangered or vulnerable," said lead author, Dr Luke Kelly, a Senior Lecturer in Ecology and Centenary Research Fellow."That's a massive number of plants and animals facing threats associated with fire."The paper, Fire and biodiversity in the Anthropocene, published in "Recent fires have burned ecosystems where wildfire has historically been rare or absent, from the tropical forests of Queensland, Southeast Asia and South America to the tundra of the Arctic Circle," Dr Kelly said."Very large and severe fires have also been observed in areas with a long history of recurrent fire, and this is consistent with observations of longer fire seasons and predictions of increased wildfire activity in the forests and shrub lands of Australia, southern Europe and the western United States."The research team also found a striking example from Australia: the total area burnt by bushfires in the eastern seaboard from August 2019 to March 2020, 12.6 million hectares, was unprecedented in scale.However, some species and ecosystems are threatened when fire doesn't occur. Frequent fires, for example, are an important part of African savanna ecosystems and less fire activity can lead to shrub encroachment, which can displace wild herbivores such as wildebeest that prefer open areas."Understanding what's causing changes in different places helps us to find effective solutions that benefit people and nature," Dr Kelly said.Researchers, including 27 authors from a combined 25 institutions around the world (including six authors from the University of Melbourne), identified three main groups of human drivers as transforming fire activity and its impacts of biodiversity: global climate change, land-use and biotic invasions. This means that people and governments around the world need to act and confront the diverse changes to the environment that are occurring."It really is time for new, bolder conservation initiatives," Dr Kelly said. "Emerging actions include large-scale habitat restoration, reintroductions of mammals that reduce fuels, creation of low-flammability green spaces and letting bushfires burn under the right conditions. The role of people is really important: Indigenous fire stewardship will enhance biodiversity and human well-being in many regions of the world."Michael Clarke, Professor of Zoology at La Trobe University, who supported the study, echoed Dr Kelly's call, saying "Our research highlights the magnitude of the challenge fire poses to animals, plants and people, given worsening climatic conditions -- a conclusion echoed in the recent Royal Commission report into last summer's fires." | Climate | 2,020 |
November 23, 2020 | https://www.sciencedaily.com/releases/2020/11/201123100954.htm | Siberian primrose has not had time to adapt to climate change | Siberian primrose, a species protected under the Habitats Directive of the European Union, spread northward from southern areas to the current Bothnian Bay as well as, through another route, to northern Norway with the gradually receding ice after the Ice Age. Compared to today, the warming of the climate was very slow at the time. | "Siberian primrose is specialised in growing on seashore meadows with low vegetation, which in Finland are formed by the post-glacial isostatic rebound. The species benefits from the lack of strong competitors and grazing that keeps the vegetation low," says Marko Hyvärinen, director of the Botany Unit of the Finnish Museum of Natural History, University of Helsinki.In 2013, researchers at the Universities of Helsinki and Oulu planted both the Norwegian and Finnish varieties (Primula nutans ssubp. finmarchicha var. finmarchica and var. jokelae) at five different botanic gardens: in their home environments in Svanvik, northern Norway, and in Oulu, northern Finland, as well as in Rauma and Helsinki further south in Finland and in Tartu, Estonia.As expected by the researchers, both varieties fared poorer in the southern gardens compared to Oulu and Svanvik, indicating that a warmer climate may be fatal for the species if it is incapable of adapting or relocating."We were surprised, however, by our finding that the Finnish populations were more successful in northern Norway than in Oulu -- even more successful than the Norwegian variety there, in its home environment," says Postdoctoral Researcher Maria Hällfors from the Research Centre for Ecological Change at the Faculty of Biological and Environmental Sciences, University of Helsinki."This indicates that global warming already affects this plant species. We can only speculate how many other species are suffering from changes to their environment, if they, too, are unable to keep up with climate change," Hällfors says.The researchers suggest that the poor adaptability of Siberian primrose in relation to global warming may contribute to the demise of these populations."Siberian primrose has no natural dispersal route further north. One way to help species like this to survive current and future challenges would be to relocate them, by human hand, further north. In other words, species could be protected by what is known as assisted migration," Hällfors contemplates.Another option is to ensure that species have sufficiently large high-quality habitats to preserve populations at a viable level. This would ensure enough genetic variation within the populations, that is, different individuals that have a higher probability to posit characteristics that are suitable in the new conditions."In any case, investments in ex situ conservation, or the conservation of species outside their natural habitat, are needed. As an example, seeds of a species can be stored in a seed bank from where the species could be re-introduced to nature." Hällfors notes. | Climate | 2,020 |
November 22, 2020 | https://www.sciencedaily.com/releases/2020/11/201122094640.htm | Breaking the ice on melting and freezing | Eric Hester has spent the last three years chasing icebergs. A mathematics graduate student at the University of Sydney in Australia, Hester and researchers at Woods Hole Oceanographic Institution in Massachusetts are studying how the shape of an iceberg shapes the way it melts. | "Ice deforms as it melts," said physical oceanographer Claudia Cenedese, who has worked with Hester on the project. "It makes these very weird shapes, especially on the bottom, like the way the wind shapes a mountain on a longer time scale."At the 73rd Annual Meeting of the American Physical Society's Division of Fluid Dynamics, Hester presented results from his group's experiments aimed at understanding how melting alters the face-changing boundary of a shrinking iceberg -- and how those alterations in turn affect the melting.The dynamics of iceberg melt is missing from most climate models, Cendese said. Including them could help with prediction: icebergs pump fresh water from ice sheets into oceans, boosting communities of living organisms. Icebergs are the dominant source of freshwater in the fjords of Greenland -- and a significant contributor to freshwater loss in Antarctica. Icebergs play a critical role in the climate, Cenedese said, and shouldn't be neglected in models. The physics of melting ice is well understood, and some models simulate it accurately, she said. Others don't. "But what you can't do in those simulations is change the shape of the ice."Icebergs form with a wide range of shapes and sizes, Hester said, and distinct thermodynamic processes affect different surfaces. The base, submerged in water, doesn't melt in the same way as the side. "And each face doesn't melt uniformly," added Cenedese.Hester conducted his experiments by submerging a dyed block of ice in a flume with a controlled flow of water passing by, and watching it melt. He and his colleagues found that the side facing a current melts faster than sides that run parallel to flow. By combining experimental and numerical approaches, Hester and his collaborators charted the relative influences of factors like relative water velocity and aspect ratio, or the proportion of height to width on a side. Not surprisingly, they found that the bottom had the slowest melt rate.Cenedese said Hester's project brings together collaborators from a range of disciplines and countries, and that a diverse collaboration was needed for such an interdisciplinary project. "Working in isolation isn't as productive in this case."Other studies discussed at the conference focused on ice formation, rather than melting. During a session on particle-laden flows, engineer Jiarong Hong from the St. Anthony Falls Laboratory at the University of Minnesota, in Minneapolis, discussed results from experiments showing how turbulence influences both the speed and distribution of snow as it falls and settles. The findings could also help scientists better understand precipitation, Hong said.Another project, presented by physicist Chao Sun from Tsinghua University in China and his group during a session on convection and buoyancy-driven flows, focused on ice formation in lakes.Working on a grant from the Natural Science Foundation of China with Ziqi Wang from Tsinghua University, Enrico Calzavarini from the University of Lille in France, and Federico Toschi from Eindhoven University of Technology in the Netherlands, Sun showed how the formation of ice on a lake is closely tied to the fluid dynamics of the water beneath.A lake may possess layers of water of differing densities and temperatures. "The water density anomalies can induce elaborate fluid dynamics beneath a moving ice front and can drastically change system behaviors," said Sun. "This has often been ignored in previous studies."Sun's group combined physical experiments, numerical simulations, and theoretical models to investigate the connection between the ice and (turbulent) convective flows. They identified four distinct regimes of different flow dynamics, each of which interacts with other layers and the ice in its own ways. Even with that complexity, though, the group developed an accurate theoretical model that could be used in future studies."It made a fair prediction of ice layer thickness and of icing time," said Sun.Since the formation and melting of ice plays such a critical role in the climate, he said, a better understanding of the fluid dynamics behind the process could help researchers identify and study accurately the markers of a warming world. "The time for ice to form and melt, for example, could potentially provide an indicator of climate change." | Climate | 2,020 |
November 22, 2020 | https://www.sciencedaily.com/releases/2020/11/201122094039.htm | U.S.-European mission launches to monitor the world's oceans | A joint U.S.-European satellite built to monitor global sea levels lifted off on a SpaceX Falcon 9 rocket from Space Launch Complex 4E at Vandenberg Air Force Base in California Saturday, Nov. 21, at 9:17 a.m. PST (12:17 p.m. EST). | About the size of a small pickup truck, Sentinel-6 Michael Freilich will extend a nearly 30-year continuous dataset on sea level collected by an ongoing collaboration of U.S. and European satellites while enhancing weather forecasts and providing detailed information on large-scale ocean currents to support ship navigation near coastlines."The Earth is changing, and this satellite will help deepen our understanding of how," said Karen St. Germain, director of NASA's Earth Science Division. "The changing Earth processes are affecting sea level globally, but the impact on local communities varies widely. International collaboration is critical to both understanding these changes and informing coastal communities around the world."After arriving in orbit, the spacecraft separated from the rocket's second stage and unfolded its twin sets of solar arrays. Ground controllers successfully acquired the satellite's signal, and initial telemetry reports showed the spacecraft in good health. Sentinel-6 Michael Freilich will now undergo a series of exhaustive checks and calibrations before it starts collecting science data in a few months' time.The spacecraft is named in honor of Michael Freilich, the former director of NASA's Earth Science Division, who was a leading figure in advancing ocean observations from space. Freilich passed away Aug. 5, 2020. His close family and friends attended the launch of the satellite that now carries his name."Michael was a tireless force in Earth sciences. Climate change and sea level rise know no national borders, and he championed international collaboration to confront the challenge," said ESA (European Space Agency) Director of Earth Observation Programmes Josef Aschbacher. "It's fitting that a satellite in his name will continue the 'gold standard' of sea level measurements for the next half-decade. This European-U.S. cooperation is exemplary and will pave the way for more cooperation opportunities in Earth observation.""Mike helped ensure NASA was a steadfast partner with scientists and space agencies worldwide, and his love of oceanography and Earth science helped us improve understanding of our beautiful planet," added Thomas Zurbuchen, NASA associate administrator for science at the agency's headquarters. "This satellite so graciously named for him by our European partners will carry out the critical work Mike so believed in -- adding to a legacy of crucial data about our oceans and paying it forward for the benefit of future generations."A joint U.S.-European satellite built to monitor global sea levels lifted off on a SpaceX Falcon 9 rocket from Space Launch Complex 4E at Vandenberg Air Force Base in California Saturday at 9:17 a.m. PST (12:17 p.m. EST).About the size of a small pickup truck, Sentinel-6 Michael Freilich will extend a nearly 30-year continuous dataset on sea level collected by an ongoing collaboration of U.S. and European satellites while enhancing weather forecasts and providing detailed information on large-scale ocean currents to support ship navigation near coastlines.The ocean-observing Sentinel-6 Michael Freilich satellite launched from Vandenberg Air Force Base in California aboard a SpaceX Falcon 9 rocket on Nov. 21, 2020 at 12:17 p.m. EST (9:17 a.m. PST, 5:17 p.m. UTC). Credit: NASA-JPL/Caltech"The Earth is changing, and this satellite will help deepen our understanding of how," said Karen St. Germain, director of NASA's Earth Science Division. "The changing Earth processes are affecting sea level globally, but the impact on local communities varies widely. International collaboration is critical to both understanding these changes and informing coastal communities around the world."After arriving in orbit, the spacecraft separated from the rocket's second stage and unfolded its twin sets of solar arrays. Ground controllers successfully acquired the satellite's signal, and initial telemetry reports showed the spacecraft in good health. Sentinel-6 Michael Freilich will now undergo a series of exhaustive checks and calibrations before it starts collecting science data in a few months' time.The spacecraft is named in honor of Michael Freilich, the former director of NASA's Earth Science Division, who was a leading figure in advancing ocean observations from space. Freilich passed away Aug. 5, 2020. His close family and friends attended the launch of the satellite that now carries his name."Michael was a tireless force in Earth sciences. Climate change and sea level rise know no national borders, and he championed international collaboration to confront the challenge," said ESA (European Space Agency) Director of Earth Observation Programmes Josef Aschbacher. "It's fitting that a satellite in his name will continue the 'gold standard' of sea level measurements for the next half-decade. This European-U.S. cooperation is exemplary and will pave the way for more cooperation opportunities in Earth observation.""Mike helped ensure NASA was a steadfast partner with scientists and space agencies worldwide, and his love of oceanography and Earth science helped us improve understanding of our beautiful planet," added Thomas Zurbuchen, NASA associate administrator for science at the agency's headquarters. "This satellite so graciously named for him by our European partners will carry out the critical work Mike so believed in -- adding to a legacy of crucial data about our oceans and paying it forward for the benefit of future generations."Sentinel-6 Michael Freilich will continue the sea level record that began in 1992 with the TOPEX/Poseidon satellite and continued with Jason-1 (2001), OSTM/Jason-2 (2008), and eventually Jason-3, which has been observing the oceans since 2016. Together, these satellites have provided a nearly 30-year record ofprecise measurements of sea level height while tracking the rate at which our oceans are rising in response to our warming climate. Sentinel-6 Michael Freilich will pass the baton to its twin, Sentinel-6B, in 2025, extending the current climate record at least another 10 years between the two satellites.This latest mission marks the first international involvement in Copernicus, the European Union's Earth Observation Programme. Along with measuring sea levels for almost the entire globe, Sentinel-6 Michael Freilich's suite of scientific instruments will also make atmospheric measurements that can be used to complement climate models and help meteorologists make better weather forecasts."NASA is but one of several partners involved in Sentinel-6 Michael Freilich, but this satellite speaks to the very core of our mission," said NASA Administrator Jim Bridenstine. "Whether 800 miles above Earth with this remarkable spacecraft or traveling to Mars to look for signs of life, whether providing farmers with agricultural data or aiding first responders with our Disasters program, we are tirelessly committed not just to learning and exploring, but to having an impact where it's needed."The initial orbit of Sentinel-6 Michael Freilich is about 12.5 miles (20.1 kilometers) lower than its ultimate operational orbit of 830 miles (1,336 kilometers). In less than a month, the satellite will receive commands to raise its orbit, trailing Jason-3 by about 30 seconds. Mission scientists and engineers will then spend about a year cross-calibrating data collected by the two satellites to ensure the continuity of sea level measurements from one satellite to the next. Sentinel-6 Michael Freilich will then take over as the primary sea level satellite and Jason-3 will provide a supporting role until the end of its mission."This mission is the very essence of partnership, precision, and incredible long-term focus," said Michael Watkins, director of NASA's Jet Propulsion Laboratory in Southern California, which manages the mission. "Sentinel-6 Michael Freilich not only provides a critical measurement,it is essential for continuing this historic multi-decadal sea level record."Sentinel-6 Michael Freilich and Sentinel-6B compose the Sentinel-6/Jason-CS (Continuity of Service) mission developed in partnership with ESA. ESA is developing the new Sentinel family of missions to support the operational needs of the Copernicus program, managed by the European Commission. Other partners include the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and National Oceanic and Atmospheric Administration, with funding support from the European Commission and technical support from France's National Centre for Space Studies."The data from this satellite, which is so critical for climate monitoring and weather forecasting, will be of unprecedented accuracy," said EUMETSAT Director-General Alain Ratier. "These data, which can only be obtained by measurements from space, will bring a wide range of benefits to people around the globe, from safer ocean travel to more precise prediction of hurricane paths, from greater understanding of sea level rise to more accurate seasonal weather forecasts, and so much more."JPL, a division of Caltech in Pasadena, California, is contributing three science instruments to each Sentinel-6 satellite: the Advanced Microwave Radiometer for Climate, the Global Navigation Satellite System -- Radio Occultation, and the Laser Retroreflector Array. NASA is also contributing launch services, ground systems supporting operation of the NASA science instruments, the science data processors for two of these instruments, and support for the U.S. component of the international Ocean Surface Topography Science Team. The launch is managed by NASA's Launch Services Program, based at the agency's Kennedy Space Center in Florida.Read the Sentinel-6 Michael Freilich press kit:To learn more about Sentinel-6 Michael Freilich, visit: | Climate | 2,020 |
November 20, 2020 | https://www.sciencedaily.com/releases/2020/11/201120142141.htm | Polar climate affects trade wind strength in tropics | The impact of sea surface temperature variations in the tropical Pacific on global climate has long been recognized. For instance, the episodic warming of the tropical Pacific during El Niño events causes melt of sea ice in far-reaching parts of the Southern Ocean via its effect on the global atmospheric circulation. A new study, published this week in the journal | Using a hierarchy of climate model simulations, the authors demonstrate the physical pathways via which polar climate variations can affect the trade winds in the tropics."Climate signals can propagate from the polar regions to the tropics either via the atmosphere or the ocean," explained Malte Stuecker, co-author and assistant professor in the Department of Oceanography and International Pacific Research Center at the University of Hawaii at Manoa. "Our climate model simulations were designed to investigate the relative role of these pathways and whether their importance differs for perturbations originating from the North pole or the South pole."The authors found that in the most complex model simulations, which include realistic representations of the ocean, atmosphere, land, and sea ice, an anomalous cooling in either hemisphere leads to a strengthening of the tropical trade winds.Lead author Sarah Kang from the Ulsan National Institute of Science and Technology in South Korea explained the reasoning behind these experiments: "One of the largest sources of uncertainty in the current generation of climate models are biases in the representation of clouds over the cold Southern Ocean. We wanted to explore what effect too much reflection of solar radiation by these clouds to outer space might have on global climate. In addition, large emissions of aerosols in the late 20th century due to industrial activity in the Northern Hemisphere from North America, Europe, and Asia resulted in a slight, temporary reduction of the global warming rate that is due to increasing greenhouse gas emissions."According to the authors' results, both of these effects could potentially explain why the Pacific trade winds were anomalously strong in recent decades."If the communication between the poles and the tropics would only occur via the atmosphere, we would see quite a distinct response in the tropics depending on whether an anomalous cooling arises from the Arctic or the Antarctic," Stuecker added. "This is because the Intertropical Convergence Zone -- the largest rainband on Earth -- is located to the north of the equator. It effectively blocks a communication from the Arctic to the equator via the atmosphere."Contrasting experiments with and without a realistic ocean representation, the authors show that enhanced upwelling of cold subsurface water in the eastern tropical Pacific is able to communicate the Arctic cooling towards the tropics and thereby strengthening the trade winds.An important implication of the results is that reducing uncertainty in simulated extratropical climate may also lead to improved simulation of climate in the tropics. The model hierarchy developed by the authors can be used to further explore two-way interactions between the tropics and polar regions both for future climate projections as well as for interpreting reconstructions of climate states in the geological past. | Climate | 2,020 |
November 20, 2020 | https://www.sciencedaily.com/releases/2020/11/201120132615.htm | New report projects severe coral bleaching globally in this century | The United Nations recently released a new report projecting future coral reef bleaching globally. The lead author of the report, Ruben van Hooidonk, is a scientist with NOAA's Cooperative Institute of Marine and Atmospheric Studies based at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science. Results highlights from the report include: | null | Climate | 2,020 |
November 20, 2020 | https://www.sciencedaily.com/releases/2020/11/201120113844.htm | Rare species of small cats inadequately protected | The Indian subcontinent is a hotspot for wild felines. A new study headed by Uppsala University now shows that only 6-11 per cent of the areas where three rare cat species have their habitat are protected. Lack of knowledge about these species has been an obstacle to understanding their needs for reserves. The research is presented in the journal | Over a third of the world's cat species inhabit the Indian subcontinent. In the new study, the researchers have explored the situation of the Prionailurus genus. It includes the rusty-spotted cat (P. rubiginosus), found in this region alone, which seems to thrive best in broadleaved forests; the fishing cat (P. viverrinus), a species associated primarily with wetlands, mangrove swamps and coastal areas; and the leopard cat (P. bengalensis), which has been observed mainly in tropical and subtropical forest areas."This study is important because it shows that many small, rare and elusive cats in the Indian subcontinent don't get as much attention as the more spectacular big cats. Nevertheless, the need to protect them is just as pressing, so the number and size of the protected areas must be increased to include more biotopes containing these species," says Mats Björklund, Professor Emeritus of Zooecology at Uppsala University.Using the geographic coordinates of sites where the various species have been seen over the years, and more recent information collected from camera-trap surveys, the scientists were able to develop ecological niche models. These could then be used to identify zones with environmental conditions that, to a high degree, suit these species individually. These models also enabled the researchers to gain a better understanding of ecological factors, such as climate, land cover and land use, that restrict or favour the occurrence of a species -- information of the utmost importance for future conservation measures.The scientists were also able to see that the most severe threats vary for the species included in the study. The leopard cat, for example, is most threatened by a warmer climate since parts of its range, such as the mountainous areas in the Western and Eastern Ghats, are clearly beginning to develop higher temperatures than this species can withstand. The rusty-spotted cat, on the other hand, is limited mainly by human cultivation of the land, especially in areas of intensive irrigation. This is of particular concern because the proportion of farmland in the region is rising. The fishing cat seems to be the Prionailurus species that, to date, has had the smallest proportion of its habitat protected.Small, shy and rare cats have the greatest need for protection. The results of this study show that, although the species studied are closely interrelated, they respond differently to environmental change. Accordingly, to cover their main biotopes, future protection must cover larger areas and more habitats accessible to these species."Some of these species, like the fishing cat, are extremely rare and probably need protection for long-term survival. The fact that only a very small proportion of the most suitable habitat for this species is protected is a warning sign that the protected-area network in the Indian subcontinent needs to be reviewed. Species like the rusty-spotted cat exist only in this region, so to ensure we don't lose them it's essential to create more protected areas," says André P. Silva, a doctoral student at the Department of Ecology and Genetics at Uppsala University and the study's lead author. | Climate | 2,020 |
November 20, 2020 | https://www.sciencedaily.com/releases/2020/11/201120095901.htm | Plant research seals importance of microbes for survival and growth | Scientists have revealed that plants have a 'sealing' mechanism supported by microbes in the root that are vital for the intake of nutrients for survival and growth. | Plant Scientists from the Future Food Beacon at the University of Nottingham have demonstrated that the mechanism controlling the root sealing in the model plant Arabidopsis thaliana influences the composition of the microbial communities inhabiting the root and reciprocally the microbes maintain the function of this mechanism. This coordination of plant-microbes plays an important part in controlling mineral nutrient content in the plant. The study has been published online by the journal Gabriel Castrillo of the Future Food Beacon and lead author on the research said: "In mammals the specialized diffusion barriers in the gut are known to coordinate with the resident microbiota to control nutrient flow. Although similar regulatory mechanisms of nutrient diffusion exist in plant roots, the contribution of the microbes to their function was unknown until now.This study has, for the first time, shown the coordination between the root diffusion barriers and the microbes colonising the root. They combine to control mineral nutrient uptake in the plant, which is crucial for proper growth and reproduction. Understanding this could lead to the development of plants more adapted to extreme abiotic conditions, with an enhanced capacity for carbon sequestration from the atmosphere. Alternatively, plants with a high content of essential mineral nutrients and the capability to exclude toxic elements could be developed."All living organisms have evolved structures to maintain a stable mineral nutrient state. In plant roots and animal guts these structures comprise specialized cell layers that function as gate-keepers to control the transfer of water and vital nutrients.To perform this function, it is crucial that cells forming these layers are sealed together. These seals need to maintain integrity in the presence of local microbial communities. In animals, microbes inhabiting the gut are known to influence the intestinal sealing and, in some cases, this can cause diseases.In roots, two main sealing mechanisms have been found: Casparian Strips, which seal cells together, and suberin deposits that influence transport across the cell plasma membrane. This research shows how these sealing mechanisms in multicellular organisms incorporate microbial function to regulate mineral nutrient balance.Food security represents a pressing global issue. Crop production must double by 2050 to keep pace with global population growth. This target is even more challenging given the impact of climate change on water availability and the drive to reduce fertilizer inputs to make agriculture become more environmentally sustainable. In both cases, developing crops with improved water and nutrient uptake efficiency would provide a solution and this. This discovery could lead to the development of new microbial approaches to control nutrient and water diffusion, presenting new opportunities to design more resilient crops, new feeding strategies and possible ways to harness carbon dioxide through carbon sequestration. | Climate | 2,020 |
November 19, 2020 | https://www.sciencedaily.com/releases/2020/11/201119165442.htm | Climate change and 'atmospheric thirst' to increase fire danger and drought in NV and CA | Climate change and a "thirsty atmosphere" will bring more extreme wildfire danger and multi-year droughts to Nevada and California by the end of this century, according to new research from the Desert Research Institute (DRI), the Scripps Institution of Oceanography at the University of California, San Diego, and the University of California, Merced. | In a new study published in According to their results, climate change projections show consistent future increases in atmospheric evaporative demand (or the "atmospheric thirst") over California and Nevada. These changes were largely driven by warmer temperatures, and would likely lead to significant on-the-ground environmental impacts."Higher evaporative demand during summer and autumn -- peak fire season in the region -- means faster drying of soil moisture and vegetation, and available fuels becoming more flammable, leading to fires that can burn faster and hotter," explained lead author Dan McEvoy, Ph.D., Assistant Research Professor of Climatology at DRI."Increased evaporative demand with warming enables fuels to be drier for longer periods," added coauthor John Abatzoglou, Ph.D., Associate Professor with the University of California, Merced. "This is a recipe for more active fire seasons."The research team found that days with extreme fire danger in summer and autumn are expected to increase four to 10 times by the end of the century. Their results also showed that multi-year droughts, similar to that experienced in California and Nevada during 2012-2016, were projected to increase three to 15 times by the end of the century."One major takeaway was that we can expect to see a lot more days in the summer and autumn with extreme fire danger related to increased temperature and evaporative demand," McEvoy said. "Another takeaway was that even in locations where precipitation may not change that much in future, droughts are going to become more severe due to higher evaporative demand."Study authors say that the cumulative effects of increases in evaporative demand will stress native ecosystems, increase fire danger, negatively impact agriculture where water demands cannot be met, and exacerbate impacts to society during periods of prolonged dryness. Several members of the research team are part of the California-Nevada Applications Program (CNAP), and will use these study results to provide resource managers with a view of possible future scenarios."These results provide information to support science-based, long-term planning for fire management agencies, forest management agencies, and water resource managers," said coauthor Julie Kalansky, Ph.D., Program Manager for CNAP. "We plan to work with partners to help integrate the findings from this paper to support building climate resilience." | Climate | 2,020 |
November 19, 2020 | https://www.sciencedaily.com/releases/2020/11/201119083931.htm | 'Oasis effect' in urban parks could contribute to greenhouse gas emissions | It will come as no surprise to anyone living in Phoenix, Arizona, that 2020 has been a record-breaking year for high temperatures. According to the National Weather Service, in 2020 the Phoenix area has surpassed all previous years for average high temperatures and excessive heat warnings. | With the combined oppressive heat and COVID-19 restrictions on travel and indoor activities like movies and restaurants, many people have turned to urban parks for outdoor recreation.And while Phoenix area parks can serve as an oasis for residents, the irrigation needed to keep parks lush and cooler comes at a high cost of water consumption.To determine this cost, a team of scientists led by hydrologist Enrique R. Vivoni of Arizona State University's (ASU) School of Earth and Space Exploration and School of Sustainable Engineering and the Built Environment spent a year collecting data on weather conditions, evapotranspiration and soil water at Encanto Golf Course in Phoenix. The results of their study have been recently published in Vivoni and his team identified that the park showed what meteorologists call the "oasis effect," which refers to the creation of a microclimate that is cooler than a surrounding dry area due to the evaporation of a water source."The word 'oasis' may conjure up the image of a pool of water surrounded by palm trees in a sandy desert," says Vivoni. "But this same effect occurs in urban parks when heat from the surrounding neighborhood is transported by winds into the park, increasing the evaporation rates."To measure the oasis effect at Encanto Golf Course, Vivoni and his team used special sensors at a weather station located within the park. These sensors measured water and energy fluxes along with carbon dioxide exchanges depicting plant photosynthesis and respiration.Vivoni and graduate students Mercedes Kindler, Zhaocheng Wang, and Eli Pérez-Ruiz worked together on the sensor deployment, data analysis and use of satellite-based products to monitor the park conditions."We set up at Encanto Park in February 2019 and all of our instruments were operational by the next month," says Kindler. "For a year, we conducted weekly or bi-weekly visits to the sites for data collection and station maintenance. It has been a great experience working on this research project, since it has allowed us to learn more about water and energy fluxes at an urban golf course."Their notable findings were two-fold. First, the oasis effect led to unexpectedly high evaporative losses during the night. Second, the oasis effect was related to the evaporation of soil water and irrigation water, and not to the activity of plants and grasses in the park."Because of the oasis effect, when we irrigate our urban parks at night, we lose vast amounts of water and we see increased carbon dioxide emissions, which could lead to higher global warming potential," says Vivoni. "This has important implications for water conservation and greenhouse gas emission management in desert cities such as Phoenix."While additional studies are needed to determine when during the day it would be preferable to irrigate, making this management change would decrease evaporative loss and the carbon dioxide emissions (which contribute to global warming) during hot, dry, windy days.It also remains to be determined how widespread this effect is within Phoenix. Given the large number of parks and golf courses, however, it is anticipated that the results of this study will yield important regional consequences to be considered by state, county and city agencies. | Climate | 2,020 |
November 18, 2020 | https://www.sciencedaily.com/releases/2020/11/201118141735.htm | Health trade-offs for wildlife as urbanization expands | City living appears to improve reproductive success for migratory tree swallows compared to breeding in more environmentally protected areas, a new five-year study suggests. But urban life comes with a big trade-off -- health hazards linked to poorer water quality. | Researchers found that city-dwelling birds bred more nestlings because of warmer local temperatures. But they also had much higher levels of mercury in their blood -- presumably from eating insects that spent their larval stages in contaminated water -- than their counterparts breeding in less urban areas.The study was conducted in central Ohio, where scientists observed tree swallows as a model species to assess their breeding success, diet and health measures in the context of varied temperatures, water quality and land use based on the location of their nests.Despite those specifics, Ohio State University researchers consider the long-term study a harbinger of what's to come for all sorts of wildlife as urbanization increases while the climate continues to warm, and how land-use changes are likely to harm water quality and threaten biodiversity.Urban land accounts for about 70 million acres in the contiguous United States, representing a 470% increase since 1945."With urbanization expanding worldwide, we are transforming the landscape. And this isn't going away," said lead author Ma?eika Sullivan, director of the Schiermeier Olentangy River Wetland Research Park at Ohio State. "My lab is looking at how urbanization affects multiple responses of ecosystems -- what those changes are and quantifying them, but also seeing what this tells us about how we can manage and conserve ecosystems and wildlife in this context."Our task, knowing wildlife are using urban settings, is to think about ways to maximize benefits and minimize the risks. There's nature in cities. So how can we make our cities a little more wild?"Sullivan, also an associate professor in Ohio State's School of Environment and Natural Resources, completed the work with graduate students Joseph Corra and Jeffry Hayes. The study was published online Nov. 15 in the journal Tree swallows are part of a guild of birds called aerial insectivores, which do all their dining on insects while in flight. Other species of swallows, as well as whip-poor-wills, nighthawks, swifts, martins and flycatchers, are also part of this group, and many of these species rely on ecosystems near water for food and habitat. Previous research has suggested that the number of North American birds has declined by about 3 billion since 1970, and the populations of some species of aerial insectivores have declined by over 50%.The magnitude of that loss alone is a striking example of biodiversity loss, Sullivan said. But the reduction in this guild of birds can also affect the economy and the quality of human life."These migratory birds are really important not just in and of themselves, but because they're controlling insects -- including pest insects that carry disease or damage agricultural crops. So they are very, very important in terms of how ecosystems function and stay in balance," he said.For research purposes, tree swallows are also useful subjects because they are "cavity nesters" that flocked to the assortment of artificial nest boxes the team constructed along waterways in Columbus, some in developed zones and others in more forested areas.From 2014-2018, the researchers observed tree swallows during their breeding season, most of May and June each year, also measuring their body weight and blood glucose and mercury levels and tracking how much of the birds' food source came from insects emerging from water or starting their pre-winged life on land. The scientists also monitored temperature and chemical water quality and quantified percentages of forested or wetland versus developed land at the breeding sites.Egg-laying occurred significantly earlier (by almost eight days), the clutch sizes were larger, and the number of fledglings that left the nest was higher at the urban sites than at protected sites. This reproductive success was largely attributable to the temperature: The air was warmer in urban sites than in protected sites by an average of 3 degrees Fahrenheit, and city locations had fewer extremely cold days."We were looking at urbanization in two different ways -- as a category of urban versus not urban, but also as gradients of urbanization. As the amount of urbanization increased, fledgling success increased," Sullivan said. "This tells us local climate is extremely important for reproductive success of tree swallows, and likely other insectivorous birds."But that success came with potential health risks related to poorer water quality in urban areas. Insects that emerge from water constituted roughly a third of the tree swallows' diet, and those insects also tend to provide more nutrition and energy than terrestrial flying insects. But the river water in urban areas had higher levels of mercury -- likely a proxy for other contaminants -- and the adult birds' blood concentration of mercury was 482% higher in city-dwellers than in those who bred in protected sites."This is an important warning," Sullivan said. "There's a whole suite of environmental contaminants out there -- pesticides, a lot of other heavy metals. So despite the advantage for breeding in these urban areas, there can be a trade-off in individual health."These findings, and the implications for birds and other wildlife affected by growing urbanization, suggest that productive urban habitats should be factored in to future municipality planning, he said.Some top considerations for insectivorous birds, as Sullivan sees it, would be establishing protected green ways, creating nesting habitats and structures to replace lost trees and other parts of the natural landscape, lowering the chances for contaminants to stream into waterways, and protecting wildlife food sources by reducing the use of pesticides and insecticides."If we had found that urbanization was negatively affecting tree swallows in all the different measures we used, that would be a very different story," Sullivan said. "But I see some rays of hope here."This work was supported by the National Science Foundation, the Ohio Department of Natural Resources, the Ohio Water Development Authority and Ohio State. | Climate | 2,020 |
November 18, 2020 | https://www.sciencedaily.com/releases/2020/11/201118080754.htm | Starved, stuffed and squandered: Consequences of decades of global nutrition transition | Just a handful of rice and beans -- a part of our world is starved. Hawaiian Pizza and ice-cream -- another part of our world is stuffed, throwing away food every day. This gap is likely to worsen, while food waste will increase and pressure on the environment will go up, a new study shows. Researchers from the Potsdam Institute for Climate Impact Research (PIK) assessed the consequences if the current nutrition transition, from scarce starch-based diets towards processed foods and animal products, continues -- the calculations combine, for the first time, estimates for under- and overweight, food composition and waste. Their findings provide a startling look ahead: By 2050, more than 4 billion people could be overweight, 1.5 billion of them obese, while 500 million people continue to be underweight. | "If the observed nutrition transition continues, we will not achieve the United Nations goal of eradicating hunger worldwide," explains Benjamin Bodirsky from PIK, lead author of the study just published in Scientific Reports. "At the same time, our future will be characterized by overweight and obesity of mind-blowing magnitude." By 2050, 45 percent of the world's population could be overweight and 16 percent obese -- compared to about 29 and 9 percent in 2010. This development is due to the insufficient global distribution of food as well as to the shift from scarcely processed plant-based diets towards unbalanced, affluent diets, where animal protein, sugar and fat displace whole grains and pulses.And that's not all as Bodirsky underlines: "The increasing waste of food and the rising consumption of animal protein mean that the environmental impact of our agricultural system will spiral out of control. Whether greenhouse gases, nitrogen pollution or deforestation: we are pushing the limits of our planet -- and exceed them."Crop and grazing land for food production cover about one third of the global land area; our food system is responsible for up to a third of global greenhouse gas emissions. The study projects that -- if current trends continue -- global food demand will increase by about 50% between 2010 and 2050, the demand for animal products like meat and milk will approximately double, a development that requires more and more land."Using the same area of land, we could produce much more plant-based food for humans than animal-based food," explains co-author Alexander Popp, head of PIK's Land Use Management Research Group. "To put it in a very simplistic way: If more people eat more meat, there's less plant-based food for the others -- plus we need more land for food production which can lead to forests being cut down. And greenhouse gas emissions rise as a consequence of keeping more animals."The study provides a first-of-its kind, consistent long-term overview of a continued global nutrition transition from 1965 to 2100, using an open-source model that forecasts how much of food demand can be attributed to factors like population growth, ageing, increasing height, growing body mass index, declining physical activity and increasing food waste. Co-author Prajal Pradhan from PIK explains: "There is enough food in the world -- the problem is that the poorest people on our planet have simply not the income to purchase it. And in rich countries, people don't feel the economic and environmental consequences of wasting food." But redistribution alone would not be sufficient, as actually both the poor and the rich eat poorly: There is a lack of knowledge about a healthy way of life and nutrition."Unhealthy diets are the world's largest health risks," co-author Sabine Gabrysch, head of PIK's Research Department on Climate Resilience explains. "While many countries in Asia and Africa currently still struggle with undernutrition and associated health problems, they are increasingly also faced with overweight, and as a consequence, with a rising burden of diabetes, cardiovascular disease and cancer," she adds. The study could provide valuable orientation about the potential development pathway of different countries and regions. It could also support much-needed pro-active policies for a qualitative transition towards sustainable and healthy diets.Sabine Gabrysch concludes: "We urgently need political measures to create an environment that promotes healthy eating habits. This could include binding regulations that limit the marketing of unhealthy snacks and promote sustainable and healthy meals in schools, hospitals and canteens. A stronger focus on nutrition education is also key, from early education in kindergarten to counseling by medical doctors and nurses. What we eat is of vital importance -- both for our own health and that of our planet." | Climate | 2,020 |
November 18, 2020 | https://www.sciencedaily.com/releases/2020/11/201118090759.htm | Study improves ability to predict how whales travel through their ocean habitat | Scientists at the New England Aquarium's Anderson Cabot Center for Ocean Life recently published a study that could help researchers learn where protections are needed the most for bowhead whales. | Dr. Dan Pendleton and Dr. Jessica Redfern partnered with Dr. Elizabeth Holmes of the National Marine Fisheries Service and Dr. Jinlun Zhang of the University of Washington for the study, which was published in the journal Most species distribution models use data such as ocean depth, temperature, and water chemistry, but with the addition of food -- one of the species' primary drivers for inhabiting an area -- the Aquarium scientists were able to improve the ability to make these predictions. The key to this model's success was calculations that estimate fluctuations in the whales' prey: zooplankton.Using prey-centric species distribution models is beneficial for understanding where the whales are now and where they will be in the future. As climate change continues to warm waters and melt sea ice, impacting where the whales' food source will likely be, this research could guide protection efforts as well as shipping routes and fishing guidelines.The study focused on the western Arctic bowhead whales in the Beaufort Sea north of Alaska, but Pendleton has hopes to use the prey-centric model to track the movements of North Atlantic right whales, a critically endangered species of 356 individuals that migrates along the east coast of the U.S. and Canada. Right whales are threatened by climate change, collisions with ships, and entanglements with fishing lines."Warm water that's been coming into the Gulf of Maine has affected the supply of their primary prey," said Pendleton, adding that the shift has pushed some right whales to migrate further north into Canadian waters to feed in late summer. "They're just not in the places that they've been for the last 40 years." | Climate | 2,020 |
November 17, 2020 | https://www.sciencedaily.com/releases/2020/11/201117192613.htm | Farms, tables and vast impacts between and beyond | Bountiful harvests in one location can mean empty water reservoirs and environmental woes far from farmlands. A unique study in this week's | Scientists at Michigan State University (MSU) and colleagues have used new sustainability science tools to understand how the increasingly irrigating farm fields to grow food reverberates through the biggest drivers of sustainability. Further, they show It's not just the farmlands that shoulder environmental impacts. Effects are felt faraway as massive water redirects gobble energy and spew emissions. And the biggest reveal: Sometimes, it's places that have no major stake in the plant-water-eat game that end up paying an environmental price."Ensuring food security while safeguarding the environment is one of the greatest challenges for the world today, yet as the world has become so globalized, it is an incredibly complicated process, and misunderstanding it or missing impacts can allow major setbacks in achieving sustainability," said Jianguo "Jack" Liu, MSU Rachel Carson Chair in Sustainability. "We need to deploy the new ways of looking at the world in a way that embraces its complexity."So, the scientists used the framework of metacoupling, which helps look not only at the irrigated farmlands, but also the massive projects to move water from one region to another. The metacoupling framework allows scientists from many different disciplines look at the interactions between socioeconomics and environmental forces -- like climate change, diet change, irrigation technologies, crop planting strategies, water diversion -- both within and across borders.They used the North China Plain (NCP), which is a major food production region, and the rest of China, which has seen significant spikes in food demand, as a demonstration, as well as one segment of China's massive South-to-North Water Transfer Project. While China was the study site, the authors note these methods for examining sustainability would be applicable in the United States and across the world.Meeting soaring food demands, the crops -- primarily wheat and maize -- require massive amounts of water. The world's largest and longest water transfer project in this study draws from Hubei Province's water reserves in southern China. The people in Hubei aren't farmers on the scale in the NCP, nor do they buy a significant portion of their cereal crops from the NCP. They are what the scientists call a "spillover" -- meaning they are not direct players in this providing/consuming food network. Yet Hubei lost significant amounts of land and water to the project dedicated to keeping the NCP wet and growing. The water transfer also generated a substantial energy footprint.The team of scientists took the food supply issue from the simplicity of solving a problem of producing food by transferring water, to a more complex one that recognized the many causes and effects that fan out far beyond the farms and tables."This study demonstrates the importance of understanding our increasingly connected world in a way that quantifies the often missed and unrecognized connections involved in feeding the world," said Elizabeth Blood, program director of the National Science Foundation's Ecosystem Science and Dynamics of Integrated Socio-Environmental Systems, which supported the work."The world is very focused on solving critical environmental problems," said Zhenci Xu, an MSU research associate and the paper's first author. "We are declaring that we cannot cherry-pick the problem we want to solve because growing crops is about more than irrigation and more about the plot of cropland. You cannot have water at this scale without using energy and changing how land is used. Which then means CO2 emissions are generated, and climate change is exacerbated. We say this is complicated, but it's also an opportunity to help make real change."The paper calls for policies to help address multiple aspects of environmental impacts in different areas simultaneously affected by the transfer of water. They also note that instead of focusing only on the supply side of the issue -- in this case the farmlands -- it can be useful to also include consumption-based policies -- such as encouraging shifts in diets that depend less on resource-intensive crops."We need to get used to looking at the many sides of every issue and be prepared likewise to come forward with many different solutions," Liu said. "We no longer live in a one-issue world."In addition to the National Science Foundation, the work was supported by, MSU, Michigan AgBioResearch, the National Key R&D Program of China, and the National Natural Science Foundation of China. | Climate | 2,020 |
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