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May 3, 2021
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https://www.sciencedaily.com/releases/2021/05/210503104821.htm
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Will your future clothes be made of algae?
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Living materials, which are made by housing biological cells within a non-living matrix, have gained popularity in recent years as scientists recognize that often the most robust materials are those that mimic nature.
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For the first time, an international team of researchers from the University of Rochester and Delft University of Technology in the Netherlands used 3D printers and a novel bioprinting technique to print algae into living, photosynthetic materials that are tough and resilient. The material has a variety of applications in the energy, medical, and fashion sectors. The research is published in the journal "Three-dimensional printing is a powerful technology for fabrication of living functional materials that have a huge potential in a wide range of environmental and human-based applications." says Srikkanth Balasubramanian, a postdoctoral research associate at Delft and the first author of the paper. "We provide the first example of an engineered photosynthetic material that is physically robust enough to be deployed in real-life applications."To create the photosynthetic materials, the researchers began with a non-living bacterial cellulose -- an organic compound that is produced and excreted by bacteria. Bacterial cellulose has many unique mechanical properties, including its flexibility, toughness, strength, and ability to retain its shape, even when twisted, crushed, or otherwise physically distorted.The bacterial cellulose is like the paper in a printer, while living microalgae acts as the ink. The researchers used a 3D printer to deposit living algae onto the bacterial cellulose.The combination of living (microalgae) and nonliving (bacterial cellulose) components resulted in a unique material that has the photosynthetic quality of the algae and the robustness of the bacterial cellulose; the material is tough and resilient while also eco-friendly, biodegradable, and simple and scalable to produce. The plant-like nature of the material means it can use photosynthesis to "feed" itself over periods of many weeks, and it is also able to be regenerated -- a small sample of the material can be grown on-site to make more materials.The unique characteristics of the material make it an ideal candidate for a variety of applications, including new products such as artificial leaves, photosynthetic skins, or photosynthetic bio-garments.Artificial leaves are materials that mimic actual leaves in that they use sunlight to convert water and carbon dioxide -- a major driver of climate change -- into oxygen and energy, much like leaves during photosynthesis. The leaves store energy in chemical form as sugars, which can then be converted into fuels. Artificial leaves therefore offer a way to produce sustainable energy in places where plants don't grow well, including outer space colonies. The artificial leaves produced by the researchers at Delft and Rochester are additionally made from eco-friendly materials, in contrast to most artificial leaf technologies currently in production, which are produced using toxic chemical methods."For artificial leaves, our materials are like taking the 'best parts' of plants -- the leaves -- which can create sustainable energy, without needing to use resources to produce parts of plants -- the stems and the roots -- that need resources but don't produce energy," says Anne S. Meyer, an associate professor of biology at Rochester. "We are making a material that is only focused on the sustainable production of energy."Another application of the material would be photosynthetic skins, which could be used for skin grafts, Meyer says. "The oxygen generated would help to kick-start healing of the damaged area, or it might be able to carry out light-activated wound healing."Besides offering sustainable energy and medical treatments, the materials could also change the fashion sector. Bio-garments made from algae would address some of the negative environmental effects of the current textile industry in that they would be high-quality fabrics that would be sustainability produced and completely biodegradable. They would also work to purify the air by removing carbon dioxide through photosynthesis and would not need to be washed as often as conventional garments, reducing water usage."Our living materials are promising because they can survive for several days with no water or nutrients access, and the material itself can be used as a seed to grow new living materials," says Marie-Eve Aubin-Tam, an associate professor of bionanoscience at Delft. "This opens the door to applications in remote areas, even in space, where the material can be seeded on site."
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Climate
| 2,021 |
May 3, 2021
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https://www.sciencedaily.com/releases/2021/05/210503104810.htm
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Less precipitation means less plant diversity
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Water is a scarce resource in many of the Earth's ecosystems. This scarcity is likely to increase in the course of climate change. This, in turn, might lead to a considerable decline in plant diversity. Using experimental data from all over the world, scientists from the Helmholtz Centre for Environmental Research (UFZ), the German Centre for Integrative Biodiversity Research (iDiv), and the Martin Luther University of Halle-Wittenberg (MLU) have demonstrated for the first time that plant biodiversity in drylands is particularly sensitive to changes in precipitation. In an article published in
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How will climate change affect the Earth's ecosystems? How will biodiversity in different regions change? Such important questions about the future are difficult to answer. In order to do so, it is important to know how the individual species and their communities will react to changing precipitation conditions, for example. But despite numerous scientific experiments worldwide, we do not have synthetic, global answers to these questions. For example, experiments differ greatly in their methodology, such as whether they add small or large amounts of water. "These studies use different methods and are located in different regions of the world," says first author Dr. Lotte Korell, a biologist at the UFZ. "And these studies yield contradictory results in many cases." Together with her colleagues, she has therefore set out to derive a general understanding from the data collected worldwide. The focus was on how an increase or decrease in precipitation affects the plant diversity of terrestrial ecosystems.In their search, she and her team found 23 usable publications, which presented results from 72 field experiments. With this data, they calculated various statistical variables that provided information about the biodiversity at the individual sites and related them to the increasing or decreasing amounts of rainfall."However, in such experiments, biodiversity depends on many factors," says Prof. Dr. Tiffany Knight, last author of the study and ecologist at the UFZ, iDiv, and MLU. For example, the size of the experiment plays an important role. If you focus on only a single experimental plot, then you might see dramatic effects of treatments on biodiversity, as plots with less water have fewer plant individuals growing there, and thus fewer species. However, at least one individual of every species might be found in at the larger scale, and thus a lower effect of the treatment on biodiversity. Indeed, the researchers found that increasing dryness has a greater effect when it is considered at small compared to larger spatial scales. "Thus, in order to draw the right conclusions from the data, you have to take into account both the local climate conditions and the spatial scale of the experiments," says Knight.In this way, the researchers have identified a clear trend. In the drylands of the world, changes in precipitation levels have a much greater effect than in wetter regions.Dry ecosystems currently occupy about 40% of the Earth's land surface. It is not easy to predict what awaits these areas against the backdrop of climate change. Although climate models do predict increasing rainfall in some dry regions, the water shortage is likely to worsen in most of them.According to the study, plant diversity is expected to increase where it becomes wetter. This is probably because the seeds of the species found there may have a better chance of germinating and becoming established.However, in light of the projected expansion of drylands, this effect is likely to benefit only relatively few regions. According to the authors, this would lead to a noticeable decline in plant diversity. "Although the plants there have adapted to the challenges of their habitats over long periods of time," says Korell, "at some point, even the most resilient survivor reaches its limits." And with every species that dries up and can no longer germinate, biodiversity is reduced.This could be bad news not only for the ecosystems but also for the inhabitants of the dry regions. After all, they account for about one third of the world's population. Many of these people struggle to make a living from the land under the most difficult conditions. If biodiversity declines along with the rainfall, this is likely to become an even greater challenge. For Korell and her colleagues, this is another pressing argument for slowing climate change. "It is also important to protect the drylands particularly well," says the researcher. The more these sensitive ecosystems are put under pressure from overgrazing and other stress factors, the more climate change is likely to affect plant diversity.
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Climate
| 2,021 |
May 3, 2021
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https://www.sciencedaily.com/releases/2021/05/210503093522.htm
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Reduction in wetland areas will affect Afrotropical migratory waterbirds
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Migratory waterbirds are particularly exposed to the effects of climate change at their breeding areas in the High Arctic and in Africa, according to a new study published in
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"Most of the earlier studies in the African-Eurasian flyways focused on the impact of climate change on Palearctic birds," says Frank Breiner, from Wetlands International, who developed the species distribution models. "Our results suggest that Afrotropical species will be even more exposed to the impact of climate change than most species from the temperate zone of the Palearctic. Species breeding in Southern and Eastern Africa, such as the already globally threatened Maccoa Duck and White-winged Flufftail are particularly exposed, but some still common species, such as the Cape Teal and Red-knobbed Coot are projected to suffer a net range loss exceeding 30%. Afrotropical species seem to be more sensitive to the changes in precipitation than Palearctic ones.""Our models project a variety of changes in the water cycle that will affect the dynamics and extent of wetlands," explains Bernhard Lehner, an Associate Professor in the Department of Geography at McGill University who led the hydrological modelling work. "This will make the species that depend on them vulnerable, as they will need to cope with alterations to their breeding grounds and natural habitats."The modelling highlighted areas of particular concern in terms of major reductions in freshwater flows and wetland area. These include the Mediterranean region, in the Tigris and Euphrates drainage basin of the Middle East, in West Africa such as the Gambia river, as well as in the Upper Zambezi and Okavango catchments in Southern Africa. Projected changes in river flow, species distribution and suitability of key sites for African-Eurasian waterbirds are available at the Critical Site Network Tool 2.0."Our findings will assist national authorities to anticipate the hydrological changes that may unfold through climate change and to have a better picture of how predicted climate change might impact migratory waterbirds and the sites for which they have responsibility," notes Vicky Jones, Flyways Science Coordinator at BirdLife International. "Feeding this information into planning and management of national site networks and policies affecting the wider landscape will be vital in ensuring populations of migratory waterbird species can be secured and supported by national site networks in the future.""Whilst protected areas will remain vital for waterbird conservation in the future, projected negative impacts on dispersive and northern breeding populations suggest that wider climate change adaptation measures, such as controlling agricultural drainage, protecting open habitats from forestry and wetland restoration may also be necessary outside of protected areas," notes James Pearce-Higgins, Science Director at BTO."What really concerns us is that waterbird species breeding in countries with less financial and technical capacity will be more exposed to climate change than in rich countries with better governance. In addition, countries where waterbirds are most exposed to climate change will also face climate change adaptation challenges for their human population," adds Szabolcs Nagy, from Wetlands International, the lead author of the study. "Therefore, it is essential that funding instruments for climate change adaptation apply a more integrated approach focusing on nature-based solutions that deliver benefits both for people and biodiversity.""The results presented in this paper have significant policy implications for flyway scale conservation of migratory waterbirds in the face of climate change," says Jacques Trouvilliez, Executive Secretary of AEWA. "The research is not only?providing increased knowledge about the vulnerability of species and their habitats to climate change on a flyway scale, it is also giving us a better understanding as to where we need to focus climate related adaptation activities for AEWA species."
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Climate
| 2,021 |
April 30, 2021
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https://www.sciencedaily.com/releases/2021/04/210430165912.htm
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Antarctic ice-sheet melting to lift sea level higher than thought, Harvard study says
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Global sea level rise associated with the possible collapse of the West Antarctic Ice Sheet has been significantly underestimated in previous studies, meaning sea level in a warming world will be greater than anticipated, according to a new study from Harvard researchers.
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The report, published in The new predictions show that in the case of a total collapse of the ice sheet, global sea level rise estimates would be amplified by an additional meter within 1,000 years."The magnitude of the effect shocked us," said Linda Pan, a Ph.D. in earth and planetary science in GSAS who co-led the study with fellow graduate student Evelyn Powell. "Previous studies that had considered the mechanism dismissed it as inconsequential.""If the West Antarctic Ice Sheet collapsed, the most widely cited estimate of the resulting global mean sea level rise that would result is 3.2 meters," said Powell. "What we've shown is that the water expulsion mechanism will add an additional meter, or 30 percent, to the total."But this is not just a story about impact that will be felt in hundreds of years. One of the simulations Pan and Powell performed indicated that by the end of this century global sea level rise caused by melting of the West Antarctic Ice Sheet would increase 20 percent by the water expulsion mechanism."Every published projection of sea level rise due to melting of the West Antarctic ice sheet that has been based on climate modeling, whether the projection extends to the end of this century or longer into the future, is going to have to be revised upward because of their work," said Jerry X. Mitrovica, the Frank B. Baird Jr. Professor of Science in the Department of Earth and Planetary Sciences and a senior author on the paper. "Every single one."Pan and Powell, both researchers in Mitrovica's lab, started this research while working on another sea level change project but switched to this one when they noticed more water expulsion from the West Antarctic ice sheet than they were expecting.The researchers wanted to investigate how the expulsion mechanism affected sea level change when the low viscosity, or the easy flowing material of the Earth's mantle beneath West Antarctica, is considered. When they incorporated this low viscosity into their calculations they realized water expulsion occurred much faster than previous models had predicted."No matter what scenario we used for the collapse of the West Antarctic Ice Sheet, we always found that this extra one meter of global sea level rise took place," Pan said.The researchers hope their calculations show that, in order to accurately estimate global sea level rise associated with melting ice sheets, scientists need to incorporate both the water expulsion effect and the mantle's low viscosity beneath Antarctica."Sea level rise doesn't stop when the ice stops melting," Pan said. "The damage we are doing to our coastlines will continue for centuries."
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Climate
| 2,021 |
April 30, 2021
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https://www.sciencedaily.com/releases/2021/04/210430120343.htm
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Brazilian Amazon released more carbon than it stored in 2010s
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The Brazilian Amazon rainforest released more carbon than it stored over the last decade -- with degradation a bigger cause than deforestation -- according to new research.
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More than 60% of the Amazon rainforest is in Brazil, and the new study used satellite monitoring to measure carbon storage from 2010-2019.The study found that degradation (parts of the forest being damaged but not destroyed) accounted for three times more carbon loss than deforestation.The research team -- including INRAE, the University of Oklahoma and the University of Exeter -- said large areas of rainforest were degraded or destroyed due to human activity and climate change, leading to carbon loss.The findings, published in Nature Climate Change, also show a significant rise in deforestation in 2019 -- 3.9 million hectares compared to about 1 million per year in 2017 and 2018 -- possibly due to weakened environmental protection in Brazil.Professor Stephen Sitch, of Exeter's Global Systems Institute, said: "The Brazilian Amazon as a whole has lost some of its biomass, and therefore released carbon."We all know the importance of Amazon deforestation for global climate change."Yet our study shows how emissions from associated forest degradation processes can be even larger."Degradation is a pervasive threat to future forest integrity and requires urgent research attention."Degradation is linked to deforestation, especially in weakened portions of a forest near deforested zones, but it is also caused by tree-felling and forest fires.Climate events, such as droughts, further increase tree mortality.Such degradation can be hard to track, but the research team used the satellite vegetation index L-VOD developed by scientists at INRAE, CEA and the CNRS.Using this index and a new technique for monitoring deforestation developed by the University of Oklahoma, the study evaluated changes in forest carbon stocks.A change of government in Brazil in 2019 brought a sharp decline in the country's environmental protection.The 3.9 million hectares of deforestation in that year is 30% more than in 2015, when extreme El Niño droughts led to increased tree mortality and wildfires. However, the study shows that carbon losses in 2015 were larger than in 2019.This demonstrates the dramatic impact that degradation can have on overall biomass and carbon storage in the rainforest.
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Climate
| 2,021 |
April 30, 2021
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https://www.sciencedaily.com/releases/2021/04/210430093222.htm
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Northern forest fires could accelerate climate change
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New research indicates that the computer-based models currently used to simulate how Earth's climate will change in the future underestimate the impact that forest fires and drying climate are having on the world's northernmost forests, which make up the largest forest biome on the planet. It's an important understanding because these northern forests absorb a significant amount of Earth's carbon dioxide.
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The finding, reached by studying 30 years of the world's forests using NASA satellite imaging data, suggests that forests won't be able to sequester as much carbon as previously expected, making efforts to reduce carbon emissions all the more urgent."Fires are intensifying, and when forests burn, carbon is released into the atmosphere," says Boston University environmental earth scientist Mark Friedl, senior author on the study published in Today's forests capture about 30 percent of all human-related CO"Current Earth systems models appear to be misrepresenting a big chunk of the global biosphere. These models simulate the atmosphere, oceans, and biosphere, and our results suggest [the model-based simulation of northern forests] has been way off," says Friedl, a BU College of Arts & Sciences professor of earth and environment and interim director of BU's Center for Remote Sensing. He is an expert in utilizing satellite imaging data to monitor Earth's ecosystems on a global scale."It is not enough for a forest to absorb and store carbon in its wood and soils. For that to be a real benefit, the forest has to remain intact -- an increasing challenge in a warming, more fire-prone climate," says Jonathan Wang, the paper's lead author. "The far north is home to vast, dense stores of carbon that are very sensitive to climate change, and it will take a lot of monitoring and effort to make sure these forests and their carbon stores remain intact."Working on his PhD in Friedl's lab, Wang researched new ways to leverage the record of data collected from the long-standing Landsat program, a joint NASA/US Geological Survey mission that has been extensively imaging Earth's surface from satellites for decades, to understand how Earth's forests are changing. Wang says new computational and machine learning techniques for combining large remote sensing datasets have become much more advanced, "enabling the monitoring of even the most remote ecosystems with unprecedented detail."He developed a method to gain richer information from 30 years of Landsat data by comparing it with more recent measurements from NASA's ICESat mission, a satellite carrying laser-based imaging technology, called LiDAR, that can detect the height of vegetation within a forest. Landsat, on the other hand, primarily detects forest cover but not how tall the trees are.Comparing the newer LiDAR measurements with imaging data gathered from Landsat during the same time period, the team then worked backwards to calculate how tall and dense the vegetation was over the last three decades. They could then determine how the biomass in Earth's northern forests has changed over time -- revealing that the forests have been losing more biomass than expected due to increasingly frequent and extensive forest fires.Specifically, Friedl says, the forests are losing conifers, trees that are emblematic of Earth's northern forests, and for good reason. "Fires come in and burn, and then the most opportunistic types of species grow back first -- like hardwoods -- which then get replaced by conifers such as black spruce," he says. "But over the last 30 years, which isn't a long time frame in the context of climate change, we see fires taking out more forests, and we see hardwoods sticking around longer rather than being replaced by conifers."Conifers are better adapted to cold climates than hardwoods, which could potentially be contributing to the dwindling overall biomass of the forests."An often-stated argument against climate action is the supposed benefits that far northern ecosystems and communities will enjoy from increased warmth," Wang says. He hopes the study's discovery will help people understand that the global climate crisis has serious issues for the far north, as well. "It may be greening, in some sense," he says, "but in reality the climate-driven increase in wildfires is undoing much of the potential benefits of a warming, greening north."Wang and Friedl's findings shed light on a question that would have been difficult to answer without the help of NASA's "eyes in the sky.""Fire regimens are changing because of climate, and many areas of the world's forests are in uninhabited areas where the effects of intense fires may not be easily noticed," Friedl says. "When big chunks of real estate in places like California go up in flames, that gets our attention. But northern forests, which hold some of the largest stocks of carbon in the world, are being impacted by fires more than we realized until now."
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Climate
| 2,021 |
April 30, 2021
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https://www.sciencedaily.com/releases/2021/04/210430093131.htm
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Icebreaker's cyclone encounter reveals faster sea ice decline
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In August 2016 a massive storm on par with a Category 2 hurricane churned in the Arctic Ocean. The cyclone led to the third-lowest sea ice extent ever recorded. But what made the Great Arctic Cyclone of 2016 particularly appealing to scientists was the proximity of the Korean icebreaker Araon.
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For the first time ever, scientists were able to see exactly what happens to the ocean and sea ice when a cyclone hits. University of Alaska Fairbanks researchers and their international colleagues recently published a new study showing that sea ice declined 5.7 times faster than normal during the storm. They were also able to prove that the rapid decline was driven by cyclone-triggered processes within the ocean."Generally, when storms come in, they decrease sea ice, but scientists didn't understand what really caused it," said lead author Xiangdong Zhang from the UAF International Arctic Research Center.There was general speculation that sea ice declined solely from atmospheric processes melting ice from above. Zhang and his team proved this theory incomplete using "in-situ" observations from directly inside the cyclone. The measurements reflected things like air and ocean temperature, radiation, wind and ocean currents.It was a stroke of good luck for science, and perhaps a bit nerve-racking for those onboard, that the icebreaker was in position to capture data from the cyclone. Usually ships try to avoid such storms, but Araon had just sailed into the middle of an ice-covered zone and was locked in an ice floe.Thanks to the ship's position so close to the storm, Xiangdong and his team were able to explain that cyclone-related sea ice loss is primarily due to two physical ocean processes.First, strong spinning winds force the surface water to move away from the cyclone. This draws deeper warm water to the surface. Despite this warm water upwelling, a small layer of cool water remains directly beneath the sea ice.That's where a second process comes into play. The strong cyclone winds act like a blender, mixing the surface water.Together, the warm water upwelling and the surface turbulence warm the entire upper ocean water column and melt the sea ice from below.Although the August storm raged for only 10 days, there were lasting effects."It's not just the storm itself," explained Zhang. "It has lingering effects because of the enhanced ice-albedo feedback."The enlarged patches of open water from the storm absorb more heat, which melts more sea ice, causing even more open water. From Aug. 13-22, the amount of sea ice in the entire Arctic Ocean declined by 230,000 square miles, an area more than twice the size of the state of Arizona.Xiangdong is now working with a new computer model for the Department of Energy to evaluate whether climate change will lead to more Arctic cyclones. Previous research shows that over the past half-century, the number and intensity of cyclones in the Arctic have increased. Some of those storms, like the biggest Arctic cyclone on record in 2012, also led to record low sea ice extent.
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Climate
| 2,021 |
April 29, 2021
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https://www.sciencedaily.com/releases/2021/04/210429141949.htm
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Lightning and subvisible discharges produce molecules that clean the atmosphere
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Lightning bolts break apart nitrogen and oxygen molecules in the atmosphere and create reactive chemicals that affect greenhouse gases. Now, a team of atmospheric chemists and lightning scientists have found that lightning bolts and, surprisingly, subvisible discharges that cannot be seen by cameras or the naked eye produce extreme amounts of the hydroxyl radical -- OH -- and hydroperoxyl radical -- HO
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The hydroxyl radical is important in the atmosphere because it initiates chemical reactions and breaks down molecules like the greenhouse gas methane. OH is the main driver of many compositional changes in the atmosphere."Initially, we looked at these huge OH and HOThe data was from an instrument on a plane flown above Colorado and Oklahoma in 2012 looking at the chemical changes that thunderstorms and lightning make to the atmosphere.But a few years ago, Brune took the data off the shelf, saw that the signals were really hydroxyl and hydroperoxyl, and then worked with a graduate student and research associate to see if these signals could be produced by sparks and subvisible discharges in the laboratory. Then they did a reanalysis of the thunderstrom and lightning dataset."With the help of a great undergraduate intern," said Brune, "we were able to link the huge signals seen by our instrument flying through the thunderstorm clouds to the lightning measurements made from the ground."The researchers report their results online today (April 29) in Brune notes that airplanes avoid flying through the rapidly rising cores of thunderstorms because it is dangerous, but can sample the anvil, the top portion of the cloud that spreads outward in the direction of the wind. Visible lightning happens in the part of the anvil near the thunderstorm core."Through history, people were only interested in lightning bolts because of what they could do on the ground," said Brune. "Now there is increasing interest in the weaker electrical discharges in thunderstorms that lead to lightning bolts."Most lightning never strikes the ground, and the lightning that stays in the clouds is particularly important for affecting ozone, and important greenhouse gas, in the upper atmosphere. It was known that lightning can split water to form hydroxyl and hydroperoxyl, but this process had never been observed before in thunderstorms.What confused Brune's team initially was that their instrument recorded high levels of hydroxyl and hydroperoxyl in areas of the cloud where there was no lightning visible from the aircraft or the ground. Experiments in the lab showed that weak electrical current, much less energetic than that of visible lightning, could produce these same components.While the researchers found hydroxyl and hydroperoxyl in areas with subvisible lightning, they found little evidence of ozone and no evidence of nitric oxide, which requires visible lightning to form. If subvisible lightning occurs routinely, then the hydroxyl and hydroperoxyl these electrical events create need to be included in atmospheric models. Currently, they are not.According to the researchers, "Lightning-generated OH (hydroxyl) in all storms happening globally can be responsible for a highly uncertain but substantial 2% to 16% of global atmospheric OH oxidation.""These results are highly uncertain, partly because we do not know how these measurements apply to the rest of the globe," said Brune. "We only flew over Colorado and Oklahoma. Most thunderstorms are in the tropics. The whole structure of high plains storms is different than those in the tropics. Clearly we need more aircraft measurements to reduce this uncertainty."Other researchers at Penn State include Patrick J. McFarland, undergraduate; David O. Miller, doctoral recipient; and Jena M. Jenkins, doctoral candidate, all in meteorology and atmospheric science.Also working on the project were Eric Bruning, associate professor of atmospheric science, Texas Tech University; Sean Waugh, research meteorologist, and Donald MacGorman, senior research scientist, both at NOAA National Severe Storm Laboratory; Xinrong Ren, physical scientist, NOAA Air Resources Laboratory; Jingqiu Mao, assistant professor of atmospheric chemistry, Univeristy of Alaska; and Jeff Peischl, senior professional research assistant, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder.The National Science Foundation, NASA, and the National Oceanic and Atmospheric Administration supported this work.
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Climate
| 2,021 |
April 29, 2021
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https://www.sciencedaily.com/releases/2021/04/210429112423.htm
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Was North America populated by 'stepping stone' migration across Bering Sea?
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For thousands of years during the last ice age, generations of maritime migrants paddled skin boats eastward across shallow ocean waters from Asia to present-day Alaska. They voyaged from island to island and ultimately to shore, surviving on bountiful seaweeds, fish, shellfish, birds and game harvested from coastal and nearshore biomes. Their island-rich route was possible due to a shifting archipelago that stretched almost 900 miles from one continent to the other.
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A new study from the University of Kansas in partnership with universities in Bologna and Urbino, Italy, documents the newly named Bering Transitory Archipelago and then points to how, when and where the first Americans may have crossed. The authors' stepping-stones hypothesis depends on scores of islands that emerged during the last ice age as sea level fell when ocean waters were locked in glaciers and later rose when ice sheets melted. The two-part study, just published in the open-access journal The "stepping-stones" idea hinges on retrospective mapping of sea levels while accounting for isostacy -- deformation of the Earth's crust due to the changing depth and weight of ice and water, reaching its greatest extreme during the Last Glacial Maximum about 20,500 years ago."We digitally discovered a geographic feature of considerable size that had never been properly documented in scientific literature," said principal author Jerome Dobson, professor emeritus of geography at KU. "We named it the Bering Transitory Archipelago; it existed from about 30,000 years ago through 8,000 years ago. When we saw it, we immediately thought, 'Wow, maybe that's how the first Americans came across.' And, in fact, everything we've tested seems to bear that out -- it does seem to be true."For more than a decade, researchers have pondered a mystery within a mystery. Mitochondrial DNA indicates that migrants were isolated somewhere for up to 15,000 years on their way over from Asia to North America. The Beringian Standstill Hypothesis arises from the fact that today Native American DNA is quite different from Asian DNA, a clear indication of genetic drift of such magnitude that it can only have happened over long periods of time in nearly complete isolation from the Asian source population. The Bering Transitory Archipelago provides a suitable refugium with internal connectivity and outward isolation.Dobson said people crossing the Bering Sea probably didn't have sails but could have been experienced in paddling skin boats like the kayaks and umiaks that Inuits use today."They probably traveled in small groups," he said, "either from Asia or islands off the coast of Asia. Some maritime people are known to have existed 27,000 years ago on northern Japanese islands. They probably were maritime people -- not just living on islands, but actually practicing maritime culture, economy and travel."Dobson recently received the American Geographical Society's Cullum Geographical Medal (the same gold medal that Neil Armstrong won for flying to the moon and Rachel Carson won for writing "Silent Spring"). He named and continuously champions "aquaterra" -- all lands that were exposed and inundated repeatedly during the Late Pleistocene ice ages -- thus creating a zone of archeological promise scattered offshore from all coastal regions around the globe.Recently, Dobson and co-authors Giorgio Spada of the University of Bologna and Gaia Galassi of Urbino University "Carlo Bo" applied an improved Glacial Isostatic Adjustment model to nine global choke points, meaning isthmuses and straits that have funneled transport and trade throughout history. Significant human migrations are known to have occurred across some of them, including "Beringia" -- all portions of the Bering Sea that were exposed before, during and after the Last Glacial Maximum."These Italian ocean scientists read my 'Aquaterra' paper and took it upon themselves to refine the boundaries of aquaterra for the whole world at coarse resolution and for Beringia itself at fine resolution," Dobson said. "Later we agreed to join forces and tackle those nine global choke points. At the end of that study, we suddenly spotted these islands in the Bering Sea, and that became our focus. This had an immediate potential because it could be a real game-changer in terms of all sciences understanding how migration worked in the past. We found startling results in certain other choke points and have begun analyzing them as well."In Beringia, the three investigators contend, this action produced a "conveyor belt" of islands that rose from the sea and fell back again, pushing bands of people eastward. "The first islands to appear were just off the coast of Siberia," the KU researcher said. "Then islands appeared ever eastward. Most likely migrants kept expanding eastward, too, generally to islands within view and an easy paddle away."By 10,500 years ago, when the Bering Strait itself first appeared, almost all islands in the west had submerged. Only three islands remained, and paddling distances had increased accordingly. Thus, occupants were forced to evacuate, and they faced a clear choice: return to Asia, which they knew to be populated and may even have left due to population pressures and resource constraints, or paddle east to less known territory, perhaps less populated islands with ample resources.To fully confirm the idea set forth in the new paper, Dobson said researchers from many fields will need to collaborate as one geographer and two ocean scientists have done here."We ourselves are at a stage where we definitely need underwater confirmation," he said. "No doubt underwater archaeologists by title will prevail in that quest, but other disciplines, specialties and fields are essential. Working together plus scouring diverse literature, we presented a fundamentally new physical geography for scientists to contemplate. That should entice every relevant discipline to question conventional theory and explore new ideas regarding how, when and where people came to North America. More broadly, aquaterra can serve as a unifying theme for understanding human migrations, demic expansions, evolutionary biology, culture, settlement and endless other topics."
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Climate
| 2,021 |
April 29, 2021
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https://www.sciencedaily.com/releases/2021/04/210429112330.htm
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The Arctic's greening, but it won't save us
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There was a hope that as more plants start to grow in Arctic and boreal latitudes as our warming climate makes those regions more hospitable for plants, those photosynthesizing plants would work to help sequester the atmospheric carbon dioxide that helped them flourish in the first place. But new research led by scientists at UC Irvine and Boston University, out in
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"What does greening really mean? Can we really trust it to save us from climate change?" said Jon Wang, an Earth system scientist at UCI who the led the work alongside BU Earth & Environment professor Mark Friedl. "A big question is: What'll happen to the carbon that's currently stored in these forests as above-ground biomass in the face of a changing climate?"The answer, it turns out, is that a lot of the carbon isn't staying stored in the plants, because as fires and timber harvests at those latitudes become more and more common as climate change makes those parts of the world hotter and drier and more arable at rates sometimes twice that seen at lower latitudes, much of the new green biomass isn't storing carbon -- it's combusting during wildfires."What we found overall is across this whole domain over the past 31 years the carbon stocks have increased modestly," Wang said. "What we estimate is that 430 million metric tons of biomass has accumulated over the last 31 years -- but across this domain it would've been nearly double if it weren't for these fires and harvests that are keeping it down."The assumption before, Wang explained, was that greening was happening and it was going to help draw climate-warming carbon dioxide concentrations down -- but no-one knew the exact extent of that help.To test the assumption, Wang and his team combined observational data from two different satellite missions from the US Geological Survey and NASA, Landsat and ICESat, so they could model the amount of carbon stored in biomass across a 2.8-million-square-kilometer region spanning Canada and Alaska.ICESat data provides measurements of the height of forest canopies, while Landsat data extends back 31 years to 1984 and provides data on the reflection of different wavelengths of light from the surface of the planet -- which also provides information about plant biomass abundance. Juxtaposing that with a two-to-three times increase in the severity of wildfires in the region, and the pictures started to take shape.Wang found that plant biomass still increased, but not as much as previous computer models that aim to simulate climate change suggested they would, as those models have struggled to account for fires as a variable. The results, Wang hopes, will help scientists who construct those models -- models that tell the world what we can expect climate change to look like -- build ever-more-accurate pictures of what's in store as the century unfolds.Co-author James Randerson from UC Irvine believes these new data are important because they provide an independent means to test climate models, and because of the way they represent feedbacks between the carbon cycle and the climate system. "The rates of carbon accumulation in this region are lower that what previous studies have indicated, and will push the science community to look elsewhere for the main drivers of the terrestrial carbon sink," Randerson said.Wang added: "The change is good news for climate -- but it's also much lower than we might've expected, because these fires have raged, and gotten more severe."
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Climate
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April 29, 2021
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https://www.sciencedaily.com/releases/2021/04/210429104953.htm
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Methane release rapidly increases in the wake of the melting ice sheets
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Ice ages are not that easy to define. It may sound intuitive that an ice age represents a frozen planet, but the truth is often more nuanced than that.
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An ice age has constant glaciations and deglaciations, with ice sheets pulsating with the rhythm of changing climate. These giants have been consistently waxing and waning, exerting, and lifting pressure from the ocean floor.Several studies also show that the most recent deglaciation, Holocene (approximately 21ka-15ka ago) of the Barents Sea has had a huge impact on the release of methane into the water. A most recent study in "In our study, we expand the geological history of past Arctic methane release to the next to last interglacial, the so-called Eemian period. We have found that the similarities between the events of both Holocene and Eemian deglaciation advocate for a common driver for the episodic release of geological methane -- the retreat of ice sheets." says researcher Pierre-Antoine Dessandier, who conducted this study as a postdoctoral fellow at CAGE Centre for Arctic Gas Hydrate Environment and Climate at UiT The Arctic University of Norway.The study is based on measurements of different isotopes found in sediment cores collected from the Arctic Ocean. Isotopes are variations of chemical elements, such as carbon and oxygen, in this case. Different isotopes of the same element have different weight and interact with other chemical elements in the environment in specific ways. This means that the composition of certain isotopes is correlated to the environmental changes -- such as temperature or amount of methane in the water column or within the sediment. Isotopes are taken up and stored in the shells of tiny organisms called foraminifera and in that way get archived in the sediments for thousands of years as the tiny creatures die. Also, if methane was released for longer periods of time, the archived shells get an overgrowth of carbonate which in itself also can be tested for isotopes."The isotopic record showed that as the ice sheet melted and pressure on the seafloor lessened during the Eemian, methane was released in violent spurts, slow seeps, or a combination of both. By the time the ice disappeared completely, some thousands of years later, methane emissions had stabilized." says Dessandier.Arctic methane reservoirs consist of gas hydrates and free gas. Gas hydrates are solids, usually methane gas, frozen in a cage with water, and extremely susceptible to pressure and temperature changes in the ocean. These reservoirs are potentially large enough to raise atmospheric methane concentrations if released during the melting of glacial ice and permafrost. The "The present-day acceleration of Greenlands ice melt is an analogue to our model. We believe that the future release of methane from below and nearby these ice sheets is likely." Says DessandierIncreasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane released globally was from human activities, while natural sources contributed about 40% (230 million tons).How much methane eventually made it to the atmosphere during the Eemian and Holocene deglaciations remains uncertain. Part of the problem in quantifying this are the microbial communities that live on the seafloor and in the water and use methane to survive.But both those past deglaciations happened over thousands of years, while the current retreat of the ice sheets is unprecedentedly rapid according to the geological record."The projections of future climate change should definitely include the release of methane following in the wake of diminishing ice sheets. Past can be used to better inform the future."
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Climate
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April 29, 2021
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https://www.sciencedaily.com/releases/2021/04/210429095154.htm
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Global glacier retreat has accelerated
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An international research team including scientists from ETH Zurich has shown that almost all the world's glaciers are becoming thinner and losing mass' and that these changes are picking up pace. The team's analysis is the most comprehensive and accurate of its kind to date.
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Glaciers are a sensitive indicator of climate change -- and one that can be easily observed. Regardless of altitude or latitude, glaciers have been melting at a high rate since the mid-20th century. Until now, however, the full extent of ice loss has only been partially measured and understood. Now an international research team led by ETH Zurich and the University of Toulouse has authored a comprehensive study on global glacier retreat, which was published online in Nature on 28 April. This is the first study to include all the world's glaciers -- around 220,000 in total -- excluding the Greenland and Antarctic ice sheets. The study's spatial and temporal resolution is unprecedented -- and shows how rapidly glaciers have lost thickness and mass over the past two decades.Rising sea levels and water scarcity What was once permanent ice has declined in volume almost everywhere around the globe. Between 2000 and 2019, the world's glaciers lost a total of 267 gigatonnes (billion tonnes) of ice per year on average -- an amount that could have submerged the entire surface area of Switzerland under six metres of water every year. The loss of glacial mass also accelerated sharply during this period. Between 2000 and 2004, glaciers lost 227 gigatonnes of ice per year, but between 2015 and 2019, the lost mass amounted to 298 gigatonnes annually. Glacial melt caused up to 21 percent of the observed rise in sea levels during this period -- some 0.74 millimetres a year. Nearly half of the rise in sea levels is attributable to the thermal expansion of water as it heats up, with meltwaters from the Greenland and Antarctic ice sheets and changes in terrestrial water storage accounting for the remaining third.Among the fastest melting glaciers are those in Alaska, Iceland and the Alps. The situation is also having a profound effect on mountain glaciers in the Pamir mountains, the Hindu Kush and the Himalayas. "The situation in the Himalayas is particularly worrying," explains Romain Hugonnet, lead author of the study and researcher at ETH Zurich and the University of Toulouse. "During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face water or food shortages in a few decades." The findings of this study can improve hydrological models and be used to make more accurate predictions on a global and local scales -- for instance, to estimate how much Himalayan glacier meltwater one can anticipate over the next few decades.To their surprise, the researchers also identified areas where melt rates slowed between 2000 and 2019, such as on Greenland's east coast and in Iceland and Scandinavia. They attribute this divergent pattern to a weather anomaly in the North Atlantic that caused higher precipitation and lower temperatures between 2010 and 2019, thereby slowing ice loss. The researchers also discovered that the phenomenon known as the Karakoram anomaly is disappearing. Prior to 2010, glaciers in the Karakoram mountain range were stable -- and in some cases, even growing. However, the researchers' analysis revealed that Karakoram glaciers are now losing mass as well.Study based on stereo satellite images As a basis for the study, the research team used imagery captured on board NASA's Terra satellite, which has been orbiting the Earth once every 100 minutes since 1999 at an altitude of nearly 700 kilometres. Terra is home to ASTER, a multispectral imager with two cameras that record pairs of stereo images, allowing researchers to create high-resolution digital elevation models of all the world's glaciers. The team used the full archive of ASTER images to reconstruct a time series of glacial elevation, which enabled them to calculate changes in the thickness and mass of the ice over time.Lead author Romain Hugonnet is a doctoral student at ETH Zurich and the University of Toulouse. He worked on this project for nearly three years and spent 18 months analysing the satellite data. To process the data, the researchers used a supercomputer at the University of Northern British Columbia. Their findings will be included in the next Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC), which is due to be published later this year. "Our findings are important on a political level. The world really needs to act now to prevent the worst-case climate change scenario," says co-author Daniel Farinotti, head of the glaciology group at ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.Alongside the University of Toulouse, ETH Zurich and WSL, other institutions that participated in the study include Ulster University in the UK, the University of Oslo in Norway and the University of Northern British Columbia in Canada.
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Climate
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April 29, 2021
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https://www.sciencedaily.com/releases/2021/04/210429090227.htm
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Mammals evolved big brains after big disasters
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Scientists from Stony Brook University and the Max Planck Institute of Animal Behavior have pieced together a timeline of how brain and body size evolved in mammals over the last 150 million years. The international team of 22 scientists, including biologists, evolutionary statisticians, and anthropologists, compared the brain mass of 1400 living and extinct mammals. For the 107 fossils examined -- among them ancient whales and the oldest Old World monkey skull ever found -- they used endocranial volume data from skulls instead of brain mass data. The brain measurements were then analyzed along with body size to compare the scale of brain size to body size over deep evolutionary time.
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The findings, published in The authors say that these complex patterns urge a re-evaluation of the deeply rooted paradigm that comparing brain size to body size for any species provides a measure of the species' intelligence. "At first sight, the importance of taking the evolutionary trajectory of body size into account may seem unimportant," says Jeroen Smaers, an evolutionary biologist at Stony Brook University and first author on the study. "After all, many of the big-brained mammals such as elephants, dolphins, and great apes also have a high brain-to-body size. But this is not always the case. The California sea lion, for example, has a low relative brain size, which lies in contrast to their remarkable intelligence."By taking into account evolutionary history, the current study reveals that the California sea lion attained a low brain-to-body size because of the strong selective pressures on body size, most likely because aquatic carnivorans diversified into a semi-aquatic niche. In other words, they have a low relative brain size because of selection on increased body size, not because of selection on decreased brain size."We've overturned a long-standing dogma that relative brain size can be equivocated with intelligence," says Kamran Safi, a research scientist at the Max Planck Institute of Animal Behavior and senior author on the study. "Sometimes, relatively big brains can be the end result of a gradual decrease in body size to suit a new habitat or way of moving -- in other words, nothing to do with intelligence at all. Using relative brain size as a proxy for cognitive capacity must be set against an animal's evolutionary history and the nuances in the way brain and body have changed over the tree of life."The study further showed that most changes in brain size occurred after two cataclysmic events in Earth's history: the mass extinction 66 million years ago and a climatic transition 23-33 million years ago.After the mass extinction event at the end of the Cretaceous period, the researchers noticed a dramatic shift in brain-body scaling in lineages such as rodents, bats and carnivorans as animals radiated into the empty niches left by extinct dinosaurs. Roughly 30 million years later, a cooling climate in the Late Paleogene led to more profound changes, with seals, bears, whales, and primates all undergoing evolutionary shifts in their brain and body size."A big surprise was that much of the variation in relative brain size of mammals that live today can be explained by changes that their ancestral lineages underwent following these cataclysmic events," says Smaers. This includes evolution of the biggest mammalian brains, such as the dolphins, elephants, and great apes, which all evolved their extreme proportions after the climate change event 23-33 million years ago.The authors conclude that efforts to truly capture the evolution of intelligence will require increased effort examining neuroanatomical features, such as brain regions known for higher cognitive processes. "Brain-to-body size is of course not independent of the evolution of intelligence," says Smaers. "But it may actually be more indicative of more general adaptions to large scale environmental pressures that go beyond intelligence."
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Climate
| 2,021 |
April 30, 2021
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https://www.sciencedaily.com/releases/2021/04/210430093206.htm
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Cave deposits reveal Pleistocene permafrost thaw, absent predicted levels of CO2 release
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The vast frozen terrain of Arctic permafrost thawed several times in North America within the past 1 million years when the world's climate was not much warmer than today, researchers from the United States and Canada report in today's edition of
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Arctic permafrost contains twice as much carbon as the atmosphere. But the researchers found that the thawings -- which expel stores of carbon dioxide sequestered deep in frozen vegetation -- were not accompanied by increased levels of COThe team of researchers explored caves in Canada to look for clues left in speleothems -- mineral deposits accumulated over thousands of years -- that might help answer when in the past did Canadian permafrost thaw and how much warmer was the climate, said Boston College Associate Professor of Earth and Environmental Sciences Jeremy Shakun, a co-author of the study.The team was following up on a 2020 study that dated samples from caves in Siberia. That research found records of permafrost thawing until about 400,000 years ago, but little since then. Since the study focused on only a single region, the researchers sought to expand the search for a more representative view of the Arctic region, said Shakun, a paleoclimatologist.During the course of two years, the researchers dated 73 cave deposits from several now-frozen caves in Canada. The deposits offer tell-tale clues to climatological history because they only form when the ground is thawed and water is dripping in a cave. By dating the age of the speleothems, the scientists were able to determine when in the past the regions had thawed.Shakun said the results are very similar to the earlier Siberian study, suggesting that Arctic permafrost became more stable over the ice age cycles of the past couple million years.But he said the team was surprised to find that many of the speleothems from the high Arctic turned out to be much younger than expected. Their relatively young ages mean permafrost thawing formed mineral deposits when the world was not much warmer than it is today.Sediment cores from the Arctic Ocean hint at what might have been going on then."The summers were ice free before 400,000 years ago," Shakun said. "That would have heated the land up more during the summer and insulated it under deeper snows in the winter, causing the ground to thaw."That theory is cause for concern if correct, he added. "Half of the Arctic sea ice has disappeared since I was born, so this may be making the permafrost more vulnerable again."Second, records of the ancient atmosphere show that greenhouse gas levels were not any higher during the past intervals of permafrost thaw we identified -- this is surprising because the standard view is that massive amounts of carbon should be released to the atmosphere when the permafrost thaws.Shakun said the findings call for further research to understand what allowed the permafrost to thaw at times in the past when it was not much warmer, and why there is little evidence for a big carbon release at those times."These findings do not fit easily with typical global warming predictions for the future," said Shakun. "They may mean that scientists have overlooked processes that will prevent permafrost thaw from causing a big spike in CO
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Climate
| 2,021 |
April 28, 2021
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https://www.sciencedaily.com/releases/2021/04/210428162517.htm
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Tool to track marine litter polluting the ocean
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In an effort to fight the millions of tons of marine litter floating in the ocean, Florida State University researchers have developed a new virtual tool to track this debris.
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Their work, which was published in Eric Chassignet, director of the Center for Ocean-Atmospheric Prediction Studies and professor in the Department of Earth, Ocean and Atmospheric Science."Marine litter is found around the world, and we do not fully understand its impact on the ocean ecosystem or human health," said Eric Chassignet, director of FSU's Center for Ocean-Atmospheric Prediction Studies (COAPS) and the paper's lead author. "That's why it's important to learn more about this problem and develop effective ways to mitigate it."Marine litter is a big problem for the Earth's oceans. Animals can get entangled in debris. Scientists have found tiny pieces of plastic inside fish, turtles and birds -- litter that blocks digestive tracts and alters feeding behavior, altering growth and reproduction. Most of that marine litter is mismanaged plastic waste, which is of particular concern because plastics remain in the ocean for a long time.Understanding where marine litter goes once it's in the ocean is a big part of understanding the issue and helping individual countries and the international community to develop plans to deal with the problem. The United Nations, which funded this work, is trying to mitigate the impact of mismanaged plastic waste, and this work can inform their policies and regulations.Take the so-called Great Pacific Garbage Patch, a cluster of marine debris in the Pacific Ocean, for example. Tracking marine litter will help answer questions about whether it is growing larger and questions about how much plastic is breaking down or sinking to the bottom of the ocean. The virtual tool also shows how countries around the world are connected."Knowing where the marine litter released into the ocean by a given country goes and the origin of the litter found on the coastline of a given country are important pieces of information for policymakers," Chassignet said. "For example, it can help policymakers determine where to focus their efforts for dealing with this problem."The tracking tool uses worldwide mismanaged plastic waste data as inputs for its model. The model uses data about ocean and air currents to track marine debris starting from 2010. Fire up the website and you can watch as colorful lines swirl across the Earth's oceans. It looks pretty -- until you realize it is tracking litter.COAPS -- an interdisciplinary research center focusing on air-sea interaction, the ocean-atmosphere-land-ice earth system and climate prediction -- is 25 years old this year. Researchers at the center uses sophisticated ocean models to map the ocean and predict ocean currents that help scientists understand where marine litter released in the ocean is likely to travel and end its journey."If you have data for the past 20 years, a lot can be done in terms of modeling and simulations," Chassignet said.COAPS researchers Xiaobiao Xu and Olmo Zavala-Romero were co-authors on this paper.This work was supported by the United Nations Environment Programme.
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Climate
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April 28, 2021
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https://www.sciencedaily.com/releases/2021/04/210428140855.htm
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Uncertainty of future Southern Ocean CO2 uptake cut in half
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Anyone researching the global carbon cycle has to deal with unimaginably large numbers. The Southern Ocean -- the world's largest ocean sink region for human-made CO
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"Research has been trying to solve this problem for a long time. Now we have succeeded in reducing the great uncertainty by about 50 percent," says Jens Terhaar of the Oeschger Centre for Climate Change Research at the University of Bern.Together with Thomas Frölicher and Fortunat Joos, who are also researchers at the Oeschger Centre, Terhaar has just presented in the scientific journal "Sciences Advances" a new method for constraining the Southern Ocean's COA better constraint Southern Ocean carbon sink is a prerequisite to understand future climate change. The ocean absorbs at least one fifth of human-made COThe new calculations from Bern not only reduce uncertainties in COIn their study, the three climate scientists show why the salinity content of the ocean surface waters is a good indicator of how much human-made CO
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Climate
| 2,021 |
April 28, 2021
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https://www.sciencedaily.com/releases/2021/04/210428135528.htm
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Soil bacteria evolve with climate change
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While evolution is normally thought of as occurring over millions of years, researchers at the University of California, Irvine have discovered that bacteria can evolve in response to climate change in 18 months. In a study published in the
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Soil microbiomes -- the collection of bacteria and other microbes in soil -- are a critical engine of the global carbon cycle; microbes decompose the dead plant material to recycle nutrients back into the ecosystem and release carbon back into the atmosphere. Multiple environmental factors influence the composition and functioning of soil microbiomes, but these responses are usually studied from an ecological perspective, asking which microbial species increase or decrease in abundance as environmental conditions change. In the current study, the UCI team investigated if bacterial species in the soil also evolve when their environment changes."We know that evolution can occur very fast in bacteria, as in response to antibiotics, but we do not know how important evolution might be for bacteria in the environment with ongoing climate change," said Dr. Alex Chase, the lead author of the study and a former graduate student at UCI.Several inherent characteristics should enable soil microbes to adapt rapidly to new climate conditions. Microbes are abundant and can reproduce in only hours, so a rare genetic mutation that allows for adaptation to new climate conditions might occur by chance over a short time frame. However, most of what is known about bacterial evolution is from controlled laboratory experiments, where bacteria are grown in flasks with artificial food. It was unclear whether evolution happens fast enough in soils to be relevant to the effects of current rates of climate change."Current predictions about how climate change will affect microbiomes make the assumption that microbial species are static. We therefore wanted to test whether bacteria can evolve rapidly in natural settings such as soil," explained Dr. Chase.To measure evolution in a natural environment, the researchers deployed a first-ever bacterial evolution experiment in the field, using a soil bacterium called Curtobacterium. The researchers used 125 "microbial cages" filled with microbial food made up of dead plant material. (The cages allow the transport of water, but not other microbes.) The cages then exposed the bacteria to a range of climate conditions across an elevation gradient in Southern California. The team conducted two parallel experiments over 18 months measuring both the ecological and evolutionary responses in the bacteria."The microbial cages allowed us to control the types of bacteria that were present, while exposing them to different environmental conditions in different sites. We could then test, for instance, how the warm and arid conditions of the desert site affected the genetic diversity of a single Curtobacterium species," said Dr. Chase.After 18 months, the scientists sequenced bacterial DNA from the microbial cages of the experiments. In the first experiment containing a diverse soil microbiome, different Curtobacterium species changed in abundance, an expected ecological response. In the second experiment over the same time frame, the genetic diversity of a single Curtobacterium bacterium changed, revealing an evolutionary response to the same environmental conditions. The authors conclude that both ecological and evolutionary processes have the potential to contribute to how a soil microbiome responds to changing climate conditions."The study shows that we can observe rapid evolution in soil microbes, and this is an exciting achievement. Our next goal is to understand the importance of evolutionary adaptation for soil ecosystems under future climate change," said co-author Jennifer Martiny, professor of ecology and evolutionary biology who co-directs the UCI Microbiome Initiative.
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Climate
| 2,021 |
April 28, 2021
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https://www.sciencedaily.com/releases/2021/04/210428135525.htm
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Socially just population policies can mitigate climate change and advance global equity
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Socially just policies aimed at limiting the Earth's human population hold tremendous potential for advancing equity while simultaneously helping to mitigate the effects of climate change, Oregon State University researchers say.
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In a paper published this week in "More than 11,000 scientists from 153 countries have come together to warn that if we continue with business as usual, the result will be untold human suffering from climate change," Ripple said. "We have listed six areas, including curbing population growth in the context of social justice, as a framework for action."Since 1997, there have been more than 200 articles published in Nature and Science on climate mitigation, but just four of those discussed social justice, and only two considered population," he added. "Clearly social justice and population policy are not getting the attention they deserve in the struggle against the climate emergency."The Earth's 7.7 billion people contribute to climate change in a variety of ways, primarily through the consumption of natural resources, including non-renewable energy sources, and the greenhouse gas emissions that result from industrial processes and transportation. The more people there are on the planet, the more potential they have for affecting climate.Partly due to forced sterilization campaigns and China's one-child policy, population policies have long been viewed as a taboo topic and detrimental to social justice, Wolf says, but they can be just the opposite when developed and implemented appropriately with the goal of promoting human rights, equity and social justice."There are strong links between high rates of population growth and ecosystem impacts in developing countries connected to water and food security," he said. "Given the challenges of food and water security, effective population policies can support achieving both social justice and climate adaptation, particularly when you consider the current and projected uneven geographical distribution of the impacts of climate change. Policies that address health and education can greatly reduce fertility rates."Examples of badly needed population policy measures include improving education for girls and young women, ending child marriage and increasing the availability of voluntary, rights-based family planning services that empower all people and particularly poor women, the researchers say."Three examples of countries in which improved education for girls and young women may have contributed to significant fertility rate declines are Ethiopia, Indonesia and Kenya," Ripple says. "Among those nations, specific education reforms included instituting classes in local languages, increasing budgets for education and removing fees for attending school. Ethiopia also implemented a school lunch program, large-scale school construction took place in Indonesia, and primary school was lengthened by one year in Kenya."As part of an overall climate justice initiative, the scientists say, rich countries should do more to help fund voluntary family planning and educational opportunities for girls and young women in developing nations."It's not a balanced approach to focus on fertility rates without remembering that wealthy governments, corporations and individuals have been the primary contributors to carbon dioxide emissions and the main beneficiaries of fossil fuel consumption," Wolf said, noting the richest half of the world's population is responsible for 90% of the CO2 emissions."From both climate and social justice perspectives, affluent overconsumption by the wealthy must be addressed immediately, for example through policies like eco-taxes such as carbon pricing," Ripple added. "Reducing fertility rates alone is clearly not enough. The middle class and rich must be responsible for most of the needed reduction in emissions."Taking steps to stabilize and then gradually reduce total human numbers within a socially just framework enhances human rights and reduces the further ordeals of migration, displacement and conflict expected in this century, Wolf and Ripple say. One potential framework is contraction and convergence, which calls for simultaneously reducing net emissions (contraction) while equalizing per capita emissions (convergence). This is equitable in the sense that it entails equalizing per capita emissions globally, a stark contrast to current patterns."Social justice and the climate emergency demand that equitable population policies be prioritized in parallel with strategies involving energy, food, nature, short-lived pollutants and the economy," Ripple said. "With feedback loops, tipping points and potential climate catastrophe looming, we have to be taking steps in all of those areas and not ignoring any of them."
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Climate
| 2,021 |
April 28, 2021
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https://www.sciencedaily.com/releases/2021/04/210428132957.htm
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Seasonal water resource on the Upper Indus
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Seasonally occurring fields of aufeis (icing) constitute an important resource for the water supply of the local population in the Upper Indus Basin. However, little research has been done on them so far. Geographers at the South Asia Institute of Heidelberg University have now examined the spreading of aufeis and, for the first time, created a full inventory of these aufeis fields. The more than 3,700 accumulations of laminated ice are important for these high mountain areas between South and Central Asia, particularly with respect to hydrology and climatology.
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In the semi-arid Himalaya regions of India and Pakistan, meltwater from snow and glaciers plays an essential role for irrigation in local agriculture and hydropower generation. In this context, aufeis has been given little attention. It appears as thin sheet-like layers of ice that form through successive freezing of water and can be several meters thick. This phenomenon occurs on a seasonal basis below springsheds, along rivulets or streams under conditions of frequent freeze-thaw cycles. "In individual cases, this process is deliberately fostered through the construction of stone walls. These artificial reservoirs are used in some valleys of Upper Indus tributaries as water harvesting measures to bridge the seasonal water shortage in spring. However, the amount of ice, size and number of natural aufeis fields have been unknown so far," underlines Prof. Dr Marcus Nüsser from the South Asia Institute of Heidelberg University.The Heidelberg geographers have now compiled an inventory of these fields for the whole Upper Indus Basin and, in this context, also analysed the role of topographical parameters such as altitude and slope. The basis were several field campaigns spent in the region along with the evaluation of almost 8,300 Landsat satellite images taken between 2010 and 2020. With this imagery, the scientists were able to record the characteristic seasonal formation of aufeis and map the annually recurring bodies of ice. They detected over 3,700 aufeis fields, covering a total area of approximately 300 square kilometers. The majority of the aufeis fields lie in the Trans-Himalaya of Ladakh and on the Tibetan Plateau. In contrast, they hardly occur at all in the western part of the Upper Indus region, Marcus Nüsser explains.The study is part of a project funded by the German Research Foundation about the significance of aufeis and ice reservoirs for the population and agriculture in the Indian region of Ladakh. The participating scientists are studying the effectiveness of the different types of ice reservoirs and whether they function efficiently on a seasonal basis. "Climate change alters both the melt rate and the annual timing of runoff, which causes increasing uncertainties for irrigated agriculture," emphasises Prof. Nüsser. "Our findings may contribute to identifying suitable locations for ice reservoirs that can improve seasonal water availability for local farming. In addition, we are going to investigate the extent to which bodies of aufeis can serve as appropriate indicators of climate change."
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Climate
| 2,021 |
April 28, 2021
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https://www.sciencedaily.com/releases/2021/04/210428132941.htm
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Inactive oil wells could be big source of methane emissions
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Uncapped, idle oil wells could be leaking millions of kilograms of methane each year into the atmosphere and surface water, according to a study by the University of Cincinnati.
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Amy Townsend-Small, an associate professor of geology and geography in UC's College of Arts and Sciences, studied 37 wells on private property in the Permian Basin of Texas, the largest oil production region on Earth. She found that seven had methane emissions of as much as 132 grams per hour. The average rate was 6.2 grams per hour."Some of them were leaking a lot. Most of them were leaking a little or not at all, which is a pattern that we have seen across the oil and gas supply chain," Townsend-Small said. "A few sources are responsible for most of the leaks."The study, published in the journal "Nobody has ever gotten access to these wells in Texas," Townsend-Small said. "In my previous studies, the wells were all on public land."A 2016 study by Townsend-Small found a similar issue in inactive wells she tested in Colorado, Wyoming, Ohio and Utah. Spread across the estimated 3.1 million abandoned wells, the leaking methane is equivalent to burning more than 16 million barrels of oil, according to government estimates.Five of the inactive wells Townsend-Small studied in Texas were leaking a brine solution onto the ground, in some cases creating large ponds."I was horrified by that. I've never seen anything like that here in Ohio," Townsend-Small said. "One was gushing out so much water that people who lived there called it a lake, but it's toxic. It has dead trees all around it and smells like hydrogen sulfide."Most of the wells had been inactive for three to five years, possibly because of fluctuations in market demand. Inactive wells could be a substantial source of methane emissions if they are not subject to leak detection and repair regulations, the UC study concluded.The study was funded in part by a grant from the U.S. Department of the Interior.Previous studies have found the basin generates 2.7 billion kilograms of methane per year or nearly 4% of the total gas extracted. That's 60% higher than the average methane emissions in oil and gas production regions nationally. This was attributed to high rates of venting and flaring due to a lack of natural gas pipelines and other gas production infrastructure.Methane is a powerful greenhouse gas that scientists have linked to climate change. If the rate of methane leaks UC observed were consistent across all 102,000 idled wells in Texas, the 5.5 million kilograms of methane released would be equivalent to burning 150 million pounds of coal each year, according to an estimate by the magazine Grist and nonprofit news organization the Texas Observer.Townsend-Small and her UC undergraduate research assistant Jacob Hoschouer, a study co-author, came to Texas at the suggestion of the media organizations, which wanted to explore the environmental impact of oil wells, particularly those that are inactive or abandoned. An expert on methane emissions, Townsend-Small has studied releases from oil and natural gas wells across the country.The journalists arranged with the property owners for Townsend-Small to examine the wells.President Joe Biden's administration has pledged $16 billion in its infrastructure plan to cap abandoned oil and gas wells and mitigate abandoned mines. Hoschouer said it would be gratifying if their research could help regulators prioritize wells for capping.In the meantime, regular inspections of inactive wells using infrared cameras to identify leaks could address the problem, the UC study suggested.
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Climate
| 2,021 |
April 27, 2021
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https://www.sciencedaily.com/releases/2021/04/210427122431.htm
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Household aerosols now release more harmful smog chemicals than all UK vehicles
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Aerosol products used in the home now emit more harmful volatile organic compound (VOC) air pollution than all the vehicles in the UK, new research shows.
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A new study by the University of York and the National Centre for Atmospheric Science reveals that the picture is damaging globally with the world's population now using huge numbers of disposable aerosols -- more than 25 billion cans per year.This is estimated to lead to the release of more than 1.3 million tonnes of VOC air pollution each year, and could rise to 2.2 million tonnes by 2050.The chemicals now used in compressed aerosols are predominantly volatile organic compounds (VOCs), chemicals which are also released from cars and fuels. The report says the VOCs currently being used in aerosols are less damaging than the ozone-depleting CFCs they replaced in the 1980's. However, in the 80's when key international policy decisions were made, no-one foresaw such a large rise in global consumption.In the presence of sunlight, VOCs combine with a second pollutant, nitrogen oxides, to cause photochemical smog which is harmful to human health and damages crops and plants.In the 1990s and 2000s by far the largest source of VOC pollution in the UK was gasoline cars and fuel, but these emissions have reduced dramatically in recent years through controls such as catalytic converters on vehicles and fuel vapour recovery at filling stations.Researchers found that on average in high-income countries 10 cans of aerosol are used per person per year with the largest contributor being personal care products. The global amount emitted from aerosols every year is surging as lower and middle-income economies grow and people in these countries buy more.The report authors are calling on international policymakers to reduce the use of VOCs in compressed aerosols, either by encouraging less damaging propellants like nitrogen, or advocating the use of non-aerosol versions of products. At present VOCs are used in around 93 per cent of aerosol cans.Professor Alastair Lewis from the Department of Chemistry and a Director of the National Centre for Atmospheric Science said: "Virtually all aerosol based consumer products can be delivered in non-aerosol form, for example as dry or roll-on deodorants, bars of polish not spray. Making just small changes in what we buy could have a major impact on both outdoor and indoor air quality, and have relatively little impact on our lives."The widespread switching of aerosol propellant with non-VOC alternatives would lead to potentially meaningful reductions in surface ozone."Given the contribution of VOCs to ground-level pollution, international policy revision is required and the continued support of VOCs as a preferred replacement for halocarbons is potentially not sustainable for aerosol products longer term."The report says there are already non-aerosol alternatives that can be easily be applied in their liquid or solid forms, for example, as roll-on deodorant, hair gel, solid furniture polish, bronzing lotion, and room fragrance.Study authors conclude that the continued use of aerosols when non-aerosol alternatives exist is often down to the continuation of past consumer habits. And that the role played by aerosol VOC emissions in air pollution needs to be much more clearly articulated in messaging on air pollution and its management to the public.Professor Lewis added: "Labelling of consumer products as high VOC emitting -- and clearly linking this to poor indoor and outdoor air quality -- may drive change away from aerosols to their alternatives, as has been seen previously with the successful labelling of paints and varnishes."Amber Yeoman, a PhD student from the Wolfson Atmospheric Chemistry Laboratories was a co-author of the study which used data from industry and regulatory bodies from around the world.
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Climate
| 2,021 |
April 27, 2021
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https://www.sciencedaily.com/releases/2021/04/210427110659.htm
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Marine biodiversity: Enormous variety of animal life in the deep sea revealed
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Ecologists at the University of Cologne's Institute of Zoology have for the first time demonstrated the enormously high and also very specific species diversity of the deep sea in a comparison of 20 deep-sea basins in the Atlantic and Pacific Oceans. Over a period of 20 years, a research team led by Professor Dr Hartmut Arndt at the Institute of Zoology has compiled a body of data that for the first time allows for a comparison of the diversity of existing eukaryotes -- organisms with a cell nucleus. Sediment samples from depths of 4000 to 8350 meters, the cultivation and sequencing of populations found exclusively in the deep sea, and finally molecular analysis using high-throughput techniques are yielding a comprehensive picture of biodiversity in the deep sea. The research results have been published in
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The deep-sea floor at water depths of more than 1000 metres covers more than 60 per cent of the Earth's surface, making it the largest part of the biosphere. Yet little is known about the diversity, distribution patterns, and functional importance of organisms in this extreme and gigantic habitat. What is certain is that climate change -- e.g. through warming, acidification, or oxygen depletion -- is already having an impact on this sensitive ecosystem. In addition, the deep sea is under pressure from the growing interest in raw material extraction.Scientists previously assumed that deep-sea basins, which are all characterized by the same low temperature (0-4°C), salinity (about 3.6 per cent), high pressure (300-500bar depending on depth), and very similar sediment, have relatively low -- and also the same -- species diversity. Moreover, most deep-sea studies to date have focused on specific habitats such as hydrothermal vents and saltwater lenses. Until now, there has been a lack of data on the diversity of deep-sea plains, which make up by far the largest portion of the seafloor. 'By using a new approach of combined molecular biology and cultivation-based studies, we found substantial, highly specific local differences in organism communities with little overlap to the organism communities of coastal regions,' said Dr Alexandra Schönle, lead author of the study.Among the life forms, unicellular organisms (protists), which have been mostly overlooked in current deep-sea food web models, dominated. In addition to the calcareous chambered organisms (foraminifera) traditionally considered in studies, whose deposits dominate vast areas of the world ocean, tiny naked protists dominated, including bacterivorous and parasitic flagellates and ciliates, whose diversity significantly exceeded that of multicellular animals. Also surprising was the high proportion of parasitic forms (10 to 20 per cent), which was previously unknown on this scale. Many of them are likely to infect animals such as crustaceans or fish, but others are likely to infect protozoa.'Our results show that organic matter on the deep-sea floor is recycled through different and previously insufficiently considered components of the microbial food web, and then passed on in the food web. This is crucial for our understanding of global carbon flux,' explains Professor Dr Hartmut Arndt. 'Given the significant differences in the biodiversity of the individual deep-sea basins and their importance in the global context, the economic exploitation and foreseeable devastation of individual deep-sea basins and the sparing of other deep-sea basins seems absurd.'
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Climate
| 2,021 |
April 27, 2021
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https://www.sciencedaily.com/releases/2021/04/210427094822.htm
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The new EU climate target could phase out coal power in Europe as early as 2030
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Tightening the EU emissions trading system (EU ETS) in line with the EU Green Deal would dramatically speed up the decarbonization of Europe's power sector -- and likely cause a demise of the coal industry. In a new study a team of researchers from Potsdam, Germany has quantified the substantial shifts Europe's electricity system is about to undergo when the newly decided EU climate target gets implemented. Higher carbon prices, the authors show, are not only an inevitable step to cut emissions -- they will also lead much faster to an inexpensive electricity system powered by renewable energies.
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"Once the EU translates their recently adjusted target of cutting emissions by at least 55% in 2030 in comparison to 1990 into tighter EU ETS caps, the electricity sector will see fundamental changes surprisingly soon," says Robert Pietzcker from the Potsdam-Institute for Climate Impact Research (PIK), one of the lead authors. "In our computer simulations of the new ambitious targets, this would mean that renewables would contribute almost three fourths of the power generation already in 2030 and we would reach zero emissions in the power sector as soon as by 2040. Once the change is initiated, it can gain speed in an unprecedented way."In order to determine the impacts, the economists studied variations of the emissions reduction targets, increased electricity demand, which might arise from sector coupling, and investments in building an effective transmission grid infrastructure to better pool renewable resources across the European countries. They also analysed the effect of potential unavailability of new nuclear power deployment and carbon capture and storage (CCS) power plants designed to reduce the amount of human-made emissions of CO"All things considered, the 55% target will have massive consequences for the power sector," says Sebastian Osorio from PIK, another lead author. "Under the previous EU climate mitigation target -- which meant reducing greenhouse gas emissions by 2030 by merely 40% -- it was expected that the carbon price within the EU emissions trading system would rise to 35€ per tonne CO"In contrast to what was observed over the last years, the demise of coal will not lead to more gas-based generation in the future," adds Robert Pietzcker. "With COSeasonal hydrogen storage in combination with better interconnection between the EU member states and deployment of batteries will allow a stable operation of a clean power system based almost exclusively on renewable sources.This is not only good news for stabilizing our climate but also for the industry and end users as well, as these changes are going to be accompanied with only minor price hikes. "Shutting down fossil power plants before the end of their lifetime, and the earlier scale-up of wind and solar power in this decade will temporarily raise prices," explains co-author Renato Rodrigues from PIK. "But after 2025, costs will decrease again due to a greater availability of cheap wind and solar power, ultimately bringing electricity prices down to the levels seen over the last decade. Thus the EU is well advised to quickly translate the new target into tighter ETS caps in order to ensure an affordable and sustainable transformation of our power system."
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Climate
| 2,021 |
April 27, 2021
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https://www.sciencedaily.com/releases/2021/04/210427085802.htm
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Study first to explore combined impacts of fishing and ocean warming on fish populations
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The combined effect of rapid ocean warming and the practice of targeting big fish is affecting the viability of wild populations and global fish stock says new research by the University of Melbourne and the University of Tasmania.
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Unlike earlier studies that traditionally considered fishing and climate in isolation, the research found that ocean warming and fishing combined to impact on fish recruitment, and that this took four generations to manifest."We found a strong decline in recruitment (the process of getting new young fish into a population) in all populations that had been exposed to warming, and this effect was highest where all the largest individuals were fished out," said lead author and PhD candidate, Henry Wootton, from the University of Melbourne.Mr Wootton and his team established 18 independent populations of fish in their lab and exposed these to either control or elevated temperatures, and to one of three fisheries harvest regimes. They then followed the fate of each population for seven generations, which equates to nearly three years of lab time."Our study is the first to experimentally explore the joint impact of fishing and ocean warming on fish populations," Mr Wootton said.The research is released today in the journal Co-author Dr John Morrongiello said: "Wild fisheries provide food for billions of people worldwide, particularly in our Pacific region where fish is the major source of animal-based protein. Past fishing practices have caused spectacular fishery crashes and so it is important that we adopt management approaches that will ensure our oceans continue to maintain sustainable fisheries."He added: "Sustainable fisheries management in the face of rapid environmental change is a real challenge. Getting it right will not only provide food and economic security for millions of people worldwide but will also help protect our ocean's valuable biodiversity for generations to come."Dr Asta Audzijonyte, co-author from University of Tasmania and Pew Fellow in Marine Conservation, said it was surprising to find such strong and delayed negative impact of warming on small fish survival."We still do not fully understand why this happens, but our findings clearly show that protecting fish size diversity and large fish can increase their resilience to climate change. While reversing climate change is hard, restoring and protecting fish size diversity is one thing that we certainly can do, and we need to do it fast," she said.Dr Audzijonyte added: "Most experimental research on climate change impacts is done on relatively short timescales, where fish are studied for two or three generations at best. We found that strong negative impacts of warming only became apparent after four generations. This suggests that we might be underestimating the possible impacts of climate change on some fisheries stocks."
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Climate
| 2,021 |
April 26, 2021
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https://www.sciencedaily.com/releases/2021/04/210426154822.htm
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Researcher re-evaluates estimate of the world's high-altitude population
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New findings detailing the world's first-of-its-kind estimate of how many people live in high-altitude regions, will provide insight into future research of human physiology.
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Dr. Joshua Tremblay, a postdoctoral fellow in UBC Okanagan's School of Health and Exercise Sciences, has released updated population estimates of how many people in the world live at a high altitude.Historically the estimated number of people living at these elevations has varied widely. That's partially, he explains, because the definition of "high altitude" does not have a fixed cut-off.Using novel techniques, Dr. Tremblay's publication in the Dr. Trembly says an important part of his study was presenting population data at 500-metre intervals. And while he says the 81 million is a staggering number, it is also important to note that by going to 1,500 metres that number jumps to more than 500 million."To understand the impact of life at high altitude on human physiology, adaption, health and disease, it is imperative to know how many people live at high altitude and where they live," says Dr. Tremblay.Earlier research relied on calculating percentages of inconsistent population data and specific country-level data that has been unavailable. To address this, Dr. Tremblay combined geo-referenced population and elevation data to create global and country-level estimates of humans living at high altitude."The majority of high-altitude research is based upon lowlanders from western, educated, industrialized, rich and democratic countries who ascend to high altitude to conduct their research," says Dr. Tremblay. "Yet, there are populations who have successfully lived at high altitudes for thousands of years and who are facing increasing pressures."Living at high altitude presents major stressors to human physiology, he explains. For example, low air pressure at high altitude makes it more difficult for oxygen to enter a person's vascular systems."When low-landers travel to high altitudes our bodies develop inefficient physiological responses, which we know as altitude sickness," he says. "However, the people we studied have acquired the ability to thrive at extremely high altitudes. Their experiences can inform the diagnosis and treatment of disease for all humans, while also helping us understand how to enhance the health and well-being of high-altitude populations."With only a fraction of the world's high-altitude residents being studied, the understanding of the location and size of populations is a critical step towards understanding the differences arising from life at high altitude.Dr. Tremblay notes it's not just a case of understanding how these populations have survived for generations, but also how they thrive living in such extreme conditions. Especially as climate change continues to impact, not only the air they breathe, but every aspect of their daily lives."We tend to think of climate change as a problem for low-altitude, coastal populations, but melting snow, glaciers and extreme weather events limit water and agriculture resources," he explains. "High-altitude residents are on the frontlines of climate change. We need to expand this vital research so we can understand the effects of climate change and unavoidable low levels of oxygen on high-altitude populations."
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Climate
| 2,021 |
April 26, 2021
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https://www.sciencedaily.com/releases/2021/04/210426154807.htm
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Social tensions preceded disruptions in ancient Pueblo societies
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Climate problems alone were not enough to end periods of ancient Pueblo development in the southwestern United States.
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Drought is often blamed for the periodic disruptions of these Pueblo societies, but in a study with potential implications for the modern world, archaeologists have found evidence that slowly accumulating social tension likely played a substantial role in three dramatic upheavals in Pueblo development.The findings, detailed in an article in the "Societies that are cohesive can often find ways to overcome climate challenges," said Tim Kohler, a Washington State University archeologist and corresponding author on the study. "But societies that are riven by internal social dynamics of any sort -- which could be wealth differences, racial disparities or other divisions -- are fragile because of those factors. Then climate challenges can easily become very serious."Archeologists have long speculated about the causes of occasional upheavals in the pre-Spanish societies created by the ancestors of contemporary Pueblo peoples. These Ancestral Pueblo communities once occupied the Four Corners area of the U.S. from 500 to 1300 where today Colorado borders Utah, Arizona and New Mexico.While these communities were often stable for many decades, they experienced several disruptive social transformations before leaving the area in the late 1200s. When more precise measurements indicated that droughts coincided with these transformations, many archeologists decided that these climate challenges were their primary cause.In this study, Kohler collaborated with complexity scientists from Wageningen University in The Netherlands, led by Marten Scheffer, who have shown that loss of resilience in a system approaching a tipping point can be detected through subtle changes in fluctuation patterns."Those warning signals turn out to be strikingly universal," said Scheffer, first author on the study. "They are based on the fact that slowing down of recovery from small perturbations signals loss of resilience."Other research has found signs of such "critical slowing down" in systems as diverse as the human brain, tropical rainforests and ice caps as they approach critical transitions."When we saw the amazingly detailed data assembled by Kohler's team, we thought this would be the ideal case to see if our indicators might detect when societies become unstable -- something quite relevant in the current social context," Scheffer said.The research used tree-ring analyses of wood beams used for construction, which provided a time series of estimated tree-cutting activity spanning many centuries."This record is like a social thermometer," said Kohler, who is also affiliated with the Crow Canyon Archaeological Center in Colorado and the Santa Fe Institute in New Mexico. "Tree cutting and construction are vital components of these societies. Any deviation from normal tells you something is going on."They found that weakened recovery from interruptions in construction activity preceded three major transformations of Pueblo societies. These slow-downs were different than other interruptions, which showed quick returns to normal in the following years. The archeologists also noted increased signs of violence at the same time, confirming that tension had likely increased and that societies were nearing a tipping point.This happened at the end of the period known as the Basketmaker III, around the year 700, as well as near the ends of the periods called Pueblo I and Pueblo II, around 900 and 1140 respectively. Near the end of each period, there was also evidence of drought. The findings indicate that it was the two factors together -- social fragility and drought -- that spelled trouble for these societies.Social fragility was not at play, however, at the end of the Pueblo III period in the late 1200s when Pueblo farmers left the Four Corners with most moving far south. This study supports the theory that it was a combination of drought and conflict with outside groups that spurred the Pueblo peoples to leave.Kohler said we can still learn from what happens when climate challenges and social problems coincide."Today we face multiple social problems including rising wealth inequality along with deep political and racial divisions, just as climate change is no longer theoretical," Kohler said. "If we're not ready to face the challenges of changing climate as a cohesive society, there will be real trouble."
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Climate
| 2,021 |
April 26, 2021
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https://www.sciencedaily.com/releases/2021/04/210426154759.htm
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Cleaner water through corn
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Corn is America's top agricultural crop, and also one of its most wasteful. About half the harvest -- stalks, leaves, husks, and cobs -- remains as waste after the kernels have been stripped from the cobs. These leftovers, known as corn stover, have few commercial or industrial uses aside from burning. A new paper by engineers at UC Riverside describes an energy-efficient way to put corn stover back into the economy by transforming it into activated carbon for use in water treatment.
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Activated carbon, also called activated charcoal, is charred biological material that has been treated to create millions of microscopic pores that increase how much the material can absorb. It has many industrial uses, the most common of which is for filtering pollutants out of drinking water.Kandis Leslie Abdul-Aziz, an assistant professor of chemical and environmental engineering at UC Riverside's Marlan and Rosemary Bourns College of Engineering, runs a lab devoted to putting pernicious waste products such as plastic and plant waste known as biomass back into the economy by upcycling them into valuable commodities."I believe that as engineers we should take the lead in creating approaches that convert waste into high-value materials, fuels and chemicals, which will create new value streams and eliminate the environmental harm that comes from today's take-make-dispose model," Abdul-Aziz said.Abdul-Aziz, along with doctoral students Mark Gale and Tu Nguyen, and former UC Riverside student Marissa Moreno at Riverside City College, compared methods for producing activated carbon from charred corn stover and found that processing the biomass with hot compressed water, a process known as hydrothermal carbonization, produced activated carbon that absorbed 98% of the water pollutant vanillin.Hydrothermal carbonization created a biochar with higher surface area and larger pores when compared to slow pyrolysis- a process where corn stover is charred at increasing temperatures over a long period of time. When the researchers filtered water into which vanillin had been added through the activated carbon, its combination of larger surface area and bigger pores enabled the carbon to absorb more vanillin."Finding applications for idle resources such as corn stover is imperative to combat climate change. This research adds value to the biomass industry which can further reduce our reliance on fossil fuels," Gale said.
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Climate
| 2,021 |
April 26, 2021
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https://www.sciencedaily.com/releases/2021/04/210426140735.htm
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Microbes trap massive amounts of carbon
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Violent continental collisions and volcanic eruptions are not things normally associated with comfortable conditions for life. However, a new study, involving University of Tennessee, Knoxville, Associate Professor of Microbiology Karen Lloyd, unveils a large microbial ecosystem living deep within the earth that is fueled by chemicals produced during these tectonic cataclysms.
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When oceanic and continental plates collide, one plate is pushed down, or subducted, into the mantle and the other plate is pushed up and studded with volcanoes. This is the main process by which chemical elements are moved between Earth's surface and interior and eventually recycled back to the surface."Subduction zones are fascinating environments -- they produce volcanic mountains and serve as portals for carbon moving between the interior and exterior of Earth," said Maarten de Moor, associate professor at the National University of Costa Rica and coauthor of the study.Normally this process is thought to occur outside the reach of life because of the extremely high pressures and temperatures involved. Although life almost certainly does not exist at the extreme conditions where Earth's mantle mixes with the crust to form lava, in recent decades scientists have learned that microbes extend far deeper into Earth's crust than previously thought.This opens the possibility for discovering previously unknown types of biological interactions occurring with deep plate tectonic processes.An interdisciplinary and international team of scientists has shown that a vast microbial ecosystem primarily eats the carbon, sulfur, and iron chemicals produced during the subduction of the oceanic plate beneath Costa Rica. The team obtained these results by sampling the deep subsurface microbial communities that are brought to the surface in natural hot springs, in work funded by the Deep Carbon Observatory and the Alfred P. Sloan Foundation.The team found that this microbial ecosystem sequesters a large amount of carbon produced during subduction that would otherwise escape to the atmosphere. The process results in an estimated decrease of up to 22 percent in the amount of carbon being transported to the mantle."This work shows that carbon may be siphoned off to feed a large ecosystem that exists largely without input from the sun's energy. This means that biology might affect carbon fluxes in and out of the earth's mantle, which forces scientists to change how they think about the deep carbon cycle over geologic time scales," said Peter Barry, assistant scientist at the Woods Hole Oceanographic Institution and a coauthor of the study.The team found that these microbes -- called chemolithoautotrophs -- sequester so much carbon because of their unique diet, which allows them to make energy without sunlight."Chemolithoautotrophs are microbes that use chemical energy to build their bodies. So they're like trees, but instead of using sunlight they use chemicals," said Lloyd, a co-corresponding author of the study. "These microbes use chemicals from the subduction zone to form the base of an ecosystem that is large and filled with diverse primary and secondary producers. It's like a vast forest, but underground."This new study suggests that the known qualitative relationship between geology and biology may have significant quantitative implications for our understanding of how carbon has changed through deep time. "We already know of many ways in which biology has influenced the habitability of our planet, leading to the rise in atmospheric oxygen, for example," said Donato Giovannelli, a professor at the University of Naples Federico II and co-corresponding author of the study. "Now our ongoing work is revealing another exciting way in which life and our planet coevolved."
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Climate
| 2,021 |
April 26, 2021
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https://www.sciencedaily.com/releases/2021/04/210426140723.htm
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What spurs people to save the planet? Stories or facts?
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With climate change looming, what must people hear to convince them to change their ways to stop harming the environment? A new Johns Hopkins University study finds stories to be significantly more motivating than scientific facts -- at least for some people.
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After hearing a compelling pollution-related story in which a man died, the average person paid more for green products than after having heard scientific facts about water pollution. But the average person in the study was a Democrat. Republicans paid less after hearing the story rather than the simple facts.The findings, published this week in the journal "Our findings suggest the power of storytelling may be more like preaching to the choir," said co-author Paul J. Ferraro, an evidence-based environmental policy expert and the Bloomberg Distinguished Professor of Human Behavior and Public Policy at Johns Hopkins."For those who are not already leaning toward environmental action, stories might actually make things worse."Scientists have little scientific evidence to guide them on how best to communicate with the public about environmental threats. Increasingly, scientists have been encouraged to leave their factual comfort zones and tell more stories that connect with people personally and emotionally. But scientists are reluctant to tell such stories because, for example, no one can point to a deadly flood or a forest fire and conclusively say that the deaths were caused by climate change.The question researchers hoped to answer with this study: Does storytelling really work to change people's behavior? And if so, for whom does it work best?"We said let's do a horserace between a story and a more typical science-based message and see what actually matters for purchasing behavior," Ferraro said.Researchers conducted a field experiment involving just over 1,200 people at an agricultural event in Delaware. Everyone surveyed had lawns or gardens and lived in watershed known to be polluted.Through a random-price auction, researchers attempted to measure how much participants were willing to pay for products that reduce nutrient pollution. Before people could buy the products, they watched a video with either scientific facts or story about nutrient pollution.In the story group, participants viewed a true story about a local man's death that had plausible but tenuous connections to nutrient pollution: he died after eating contaminated shellfish. In the scientific facts group, participants viewed an evidence-based description of the impacts of nutrient pollution on ecosystems and surrounding communities.After watching the videos, all participants had a chance to purchase products costing less than $10 that could reduce storm water runoff: fertilizer, soil test kits, biochar and soaker hoses.People who heard the story were on average willing to pay more than those who heard the straight science. But the results skewed greatly when broken down by political party. The story made liberals 17 percent more willing to buy the products, while making conservatives want to spend 14 percent less.The deep behavioral divide along party lines surprised Ferraro, who typically sees little difference in behavior between Democrats and Republicans when it comes to matters such as energy conservation."We hope this study stimulates more work about how to communicate the urgency of climate change and other global environmental challenges," said lead author Hilary Byerly, a postdoctoral associate at the University of Colorado. "Should the messages come from scientists? And what is it about this type of story that provokes environmental action from Democrats but turns off Republicans?"This research was supported by contributions from the Penn Foundation, the US Department of Agriculture, The Nature Conservancy, and the National Science Foundation.
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Climate
| 2,021 |
April 26, 2021
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https://www.sciencedaily.com/releases/2021/04/210426140720.htm
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Researchers reveal that homes in floodplains are overvalued by nearly $44 billion
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Buyer beware: single-family homes in floodplains -- almost 4 million U.S. homes -- are overvalued by nearly $44 billion collectively or $11,526 per house on average, according to a new Stanford University-led study. The study, published in Proceedings of the National Academies of Science, suggests that unaware buyers and inadequate disclosure laws drive up financial risks that could destabilize the real estate market. The threat is likely to grow as climate change drives more frequent extreme weather.
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"The overvaluation we find is really concerning, especially given the increases in climate risk that are coming our way," said study lead author Miyuki Hino, who was a PhD student in the Emmett Interdisciplinary Program in Environment and Resources in Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth) at the time of the research and is now an assistant professor in the University of North Carolina at Chapel Hill's department of city and regional planning. "Improving how we communicate about flooding is an important step in the right direction."In some states, such as Florida, as many as one in six homes are in floodplains. As more people have built more homes in areas exposed to cyclones, sea-level rise and other inundation hazards, flooding damage costs have skyrocketed. Since 2000, overall flood damages have quadrupled in the U.S.More frequent extreme weather could magnify the trend. In the next 30 years, flood damages to U.S. homes are projected to rise more than 60 percent, from $20 billion to nearly $32.2 billion a year, according to nonprofit research group First Street Foundation.While some states, such as Louisiana, require detailed flood risk disclosures, others require no risk disclosures of any kind. Only two states require that sellers disclose the cost of their insurance policy -- an additional cost burden for the buyer. Most states only require disclosures by the time the contract is signed, making them unlikely to inform buyers' decisions.Unlike many past studies, which focused on single counties or cities in only a few states, the new analysis casts a nationwide net to paint a clearer picture of whether markets effectively account for publicly available information about flood risk. Hino and study senior author Marshall Burke, an associate professor of Earth system science in Stanford Earth, pored over historical and current floodplain maps as well as detailed real estate transaction data to estimate the effect of regulatory floodplain maps on property values or what the researchers call the flood zone discount.To better understand the drivers of flood zone discount, the researchers examined what happened to property values when floodplain maps were updated, causing some houses to be rezoned from outside to inside the floodplain.The analysis revealed that single-family homes zoned into a floodplain lose roughly 2% percent of their value, which works out to $10,500 for a $500,000 home or $21,000 for a $1 million home. In contrast, had buyers factored in the cost of fully insuring the floodplain home against damage, it should have pushed prices down 4.7 percent to 10.6 percent - as much as $53,000 for a $500,000 home or $106,000 for a $1 million home, according to the researchers."We like to think that markets work efficiently and incorporate all known information about risk," said Burke. "But here we find clear evidence, in an incredibly valuable market, that the market is underpricing flood risk."Perhaps unsurprisingly, the results suggest that a buyer's flood risk awareness shapes the value they perceive in a property. This awareness is likely informed by a combination of disclosure laws and the extent of flood risk within the community measured by the percentage of homes located in floodplains. More sophisticated commercial buyers, such as corporations that rent out single-family homes, discount flood zone properties by about 5 percentage points more than other buyers.The urgency of informing homebuyers about hazards from floods and other climate change-driven hazards will only grow. This past year was the tenth in a row with eight or more billion-dollar disasters in the U.S.Policymakers can help by passing legislation that promotes access to information about the extent of past flood events and strengthens real estate disclosure requirements, according to the researchers. Broader risk communication efforts -- requiring sellers to disclose flood risks and insurance costs before buyers make offers, for example -- could help rebalance real estate markets and significantly increase buy-in for flood insurance coverage, something the National Flood Insurance Program has failed to do."We spend a lot of time and energy trying to map climate hazards and how they are changing, and we need to make sure that people can access and understand that information when they need it," said Hino.The research was funded by the Sykes Family Fellowship in the Emmett Interdisciplinary Program in Environment and Resources.
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Climate
| 2,021 |
April 26, 2021
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https://www.sciencedaily.com/releases/2021/04/210426111556.htm
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Implications are global in new study predicting Human exodus in Bangladesh
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Rising sea levels and more powerful cyclonic storms, phenomena driven by the warming of oceans due to climate change, puts at immediate or potential risk an estimated 680 million people living in low-lying coastal zones (a number projected to reach more than
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In a new study, "Modeling human migration under environmental change: a case study of the effect of sea level rise in Bangladesh," researchers led by Maurizio Porfiri, an engineer at the Center for Urban Science and Progress (CUSP) at the NYU Tandon School of Engineering, apply data science to predict how the cascading effects of the migration in Bangladesh will ultimately affect 1.3 million people across the country by 2050. The work has implications for coastal populations worldwide.The new study, co-authors of which include first author Pietro De Lellis, an engineer at the University of Naples Federico II, Italy, and Manuel Ruiz Marin, a mathematician at the Technical University of Cartagena, Spain, presents a mathematical model of human migration that considers not just economic factors but also human behavior -- whether people are unwilling or unable to leave and if they later return home. It also considers the cascading effects of migration, as migrants repeatedly move to find new opportunities, and original inhabitants are displaced. The research is published in "We are not only looking at a snapshot, but we are trying to reconstruct the trajectory of the migration and looking at its evolution," said Porfiri, who is also an Institute Professor of mechanical and aerospace, biomedical, and civil and urban engineering at NYU Tandon.According to the new model, the districts in the south along the Bay of Bengal will be the first to be impacted by sea-level rise, causing a migration that will ripple across the country and affect all 64 districts. Some migrants will likely be rejected by the existing residents -- or displace them -- triggering further migrations. While the population of the capital, Dhaka, initially will surge, the results suggest that movement away from the inundated capital region will ultimately cause its population to shrink.Bangladesh is especially susceptible to sea-level rise because it is a low-lying country crisscrossed with rivers, and already experiences frequent flooding during the summer monsoon season. Its coastline on the Bay of Bengal measures about 580 kilometers (360 miles), with a large portion consumed by the Ganges river delta. An estimated 41 percent of its 163 million people live at elevations lower than 10 meters (about 32 feet).The work follows upon a 2020 study by Porfiri and Ruiz Marin that examined population migrations in Bangladesh due to sea level rise as a way to verify an approach to detect spatial associations from small datasets, through the use of specific principles of information theory.The authors emphasize that the new model can be used to study migration in response to any environmental disturbance that causes unrest, such as droughts, earthquakes or wildfires. Additionally, it is relatively simple and can make reliable predictions based on little data.An earlier migration model using the same data predicted that the central region of Bangladesh, including its capital, Dhaka, would receive the greatest number of migrants. The new study agrees, but finds that the ripple effects from that migration will ultimately cause people to leave the capital, leading to a population decline.Porfiri explained that the team's approach to mathematical modeling for reliably predicting environmental migration in Bangladesh can be applied anywhere."Droughts, desertification, floods, earthquakes, and wildfire threaten livelihood worldwide; from wealthy to developing economies, every country is vulnerable to environmental change," he said. "Mathematical models can assist in providing reliable predictions of environmental migration, which are critical for devising effective policy initiatives and improving our preparedness for future migration patterns."De Lellis added that the outputs from the model can help governments plan and prepare for the impacts of environmental disturbances by allocating resources to the most hard-hit regions and ensuring that cities are adequately equipped to deal with the influx of environmental migrants."Mathematical modeling is the only way we have to ground our future decisions," said De Lellis. "Migration has lots of sources -- [environmental disasters,] political tensions -- but in the end, we need to use science to provide useful tools for decision-makers."The research is supported by the U.S. National Science Foundation (NSF), Groups of Excellence of the region of Murcia, the Fundación Séneca, Science and Technology Agency, and Compagnia di San Paolo, Istituto Banco di Napoli -- Fondazione, project ACROSS.
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Climate
| 2,021 |
April 23, 2021
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https://www.sciencedaily.com/releases/2021/04/210423130109.htm
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Climate change affects deep-sea corals and sponges differently
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Corals and sponges are important foundations in ocean ecosystems providing structure and habitats that shelter a high number of species like fish, crabs and other creatures, particularly in the seamounts and canyons of the deep sea. Researchers at the University of New Hampshire have discovered that when it comes to climate change not all deep-sea corals and sponges are affected the same and some could be threatened if average ocean temperatures continue to increase in the deep sea of the Northwest Atlantic.
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"These deep-sea corals and sponges are ecologically important because they are foundational species that contribute to the food web and losing them could eventually lower the biodiversity of the deep sea," said Jennifer Dijkstra, a research assistant professor in UNH's Center for Coastal and Ocean Mapping.In their study, published in the journal "The paper shows that not all deep-sea corals and sponges were influenced by the same environmental variables and each has different levels of sensitivity," said Dijkstra. "Changes in temperature and dissolved oxygen, that go beyond what the deep-sea corals and sponges are used to, could stress the species' physiology affecting growth, tissue loss and reproduction."In general, deep-sea corals are found 200 to 10,000 feet below sea level where sunlight is nonexistent. Unlike shallow-water coral reefs, which are limited to warm tropical waters, deep-sea corals are found throughout the world's oceans, from tropical to polar regions, forming groves of tree or fan shapes that can reach feet to meters tall. Deep-sea sponge populations can filter water, collect bacteria and process carbon, nitrogen, and phosphorus. Deep-sea corals and sponges have been found on continental shelves, canyons and seamounts in deep seas around the world but their full extent is unknown because only 15 percent of the Earth's seafloor has been mapped with high-resolution imaging.
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Climate
| 2,021 |
April 23, 2021
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https://www.sciencedaily.com/releases/2021/04/210423130101.htm
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The largest assessment of global groundwater wells finds many are at risk of drying up
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"Jack and Jill went up the hill to fetch a pail of water." It's a silly rhyme, but one that highlights a simple fact: Humans have long relied on wells -- such as the one on the hill visited by Jack and Jill -- for their primary drinking water supply.
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Although the number of people who draw their water by pail is declining as pumps become ever more widespread, groundwater wells still supply drinking water to more than half of the world's population and sustain over 40% of irrigated agriculture. But this vital resource underfoot often gets overlooked.UC Santa Barbara assistant professors Debra Perrone and Scott Jasechko have compiled the most comprehensive assay of groundwater wells to date, spanning 40 countries that collectively account for half of all global groundwater pumping. Their study, the cover story of the April 23 edition of the journal "We analyzed construction records for tens of millions of groundwater wells around the world," said Jasechko, of the university's Bren School of Environmental Science & Management, "and the big take home is that many wells are at risk of running dry." Up to one in five wells in their survey, to be exact."These groundwater wells are used to withdraw water for household use or irrigation," added Perrone, a faculty member in the Environmental Studies Program. "Our study is the first time that groundwater wells and water level observations have been stitched together like this, providing local insights at the global scale."Reaching these conclusions required the better part of six years' work by Perrone and Jasechko. The researchers culled their data from more than 100 unique databases around the world, sometimes in different formats and languages.The first step involved compiling roughly 39 million records of functional groundwater wells that included depth, purpose, location and construction date. Rather than delegate processing the data to an algorithm or AI, the researchers carefully went through tidying it up manually. "We wanted to be sure we understood the limitations and nuances for each database we analyzed," Jasechko said.With the data sorted, the authors compared the depths of local water tables against well depths. They found that 6 to 20% of the wells in their global sample were at risk of running dry if water levels continue to decline by just a few meters. They sought to find trends in the depths of new wells compared to existing wells in a given area from 1950 through 2015. While newer wells tended to be deeper than older ones, the trend was not ubiquitous, they said. Functional wells were not getting substantially deeper in many of the areas they surveyed.The researchers then pulled data from roughly 1.1 million monitoring wells, which provide measurements of groundwater levels and conditions. These records supplied not only an account of where the water table lay, but also how much it fluctuated over the course of the year. Seasonal variation, they found, was typically within one meter.By comparing depth trends to measurements from nearby monitoring wells, Perrone and Jasechko could also deduce how close functional wells were to drying out. They found that in many areas groundwater levels are declining, yet new wells are not being drilled deeper to keep pace with the falling water table. Since wells aren't getting substantially deeper in many areas, newer wells are at least as vulnerable as older wells should groundwater levels continue to decline."In some places, groundwater levels are close to the bottom of wells," Perrone stated. "If groundwater levels continue to decline in these places, wells will go dry, leaving people without access to water."The two researchers also availed themselves of data from NASA's GRACE mission. The pair of GRACE satellites detect small differences in the Earth's gravitational field as they orbit the planet. This provided Perrone and Jasechko with information about groundwater reserves for regions where data from monitoring wells is limited."We only have groundwater level monitoring data for a few dozen countries," Jasechko said, "but GRACE data allows us to explore changes in water storage around the globe." While the resolution was coarse, the additional information confirmed the disconnect between declining groundwater and the construction of deeper wells.There are many reasons not to drill deeper. It's much more expensive in terms of drilling and operational costs. The quality of groundwater can also decrease at depth, often becoming more saline toward the bottom of an aquifer."Drilling wells is expensive," Jasechko remarked. "Even if fresh water exists deep underground, not every individual or household has the capital to drill a new well to access it, which raises concerns about equity when wells run dry."The pair hope to expand the coverage of their dataset, especially to countries like China, Iran and Pakistan, three major users of groundwater that the researchers could not obtain records from. They also plan to investigate the extent of groundwater decline in future research, looking for information on how quickly water tables are dropping and where the trend is accelerating.Groundwater can provide a lifeline in even the most arid regions.Perrone and Jasechko have made a name for themselves in the field of groundwater research by approaching the topic with enormous datasets like this one. The global study comes on the heels of another paper published in Nature on groundwater resources across the United States. There, they revealed the extent to which rivers across the country are losing flow to aquifers, in part due to pumping.Together, the findings paint a broad picture not just of wells in danger, but of dwindling groundwater resources as a whole. While pumping may have the most direct impact on aquifers, the authors note, human activity has many indirect effects on groundwater quality and levels. Industrial activity, water diversion and even pavement and runoff affect the water beneath our feet. Climate change may exert the greatest influence over the long term, as it alters the distribution and intensity of precipitation and evapotranspiration from plants and soils worldwide."These findings highlight the importance of groundwater resources and groundwater management to the global community," Perrone said. "Putting all the data together reveals that declining groundwater levels threaten wells in many places across the world."Groundwater sustainability is a complex issue with a lot of considerations and tradeoffs, the authors acknowledged. Deciding on a course of action won't be easy, but compiling and analyzing large datasets like this are a critical first-step in tackling the challenge. "With these data, we can make more informed management decisions to help us use groundwater sustainably," Perrone said.
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Climate
| 2,021 |
April 23, 2021
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https://www.sciencedaily.com/releases/2021/04/210423085733.htm
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Climate-friendly microbes chomp dead plants without releasing heat-trapping methane
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The tree of life just got a little bigger: A team of scientists from the U.S. and China has identified an entirely new group of microbes quietly living in hot springs, geothermal systems and hydrothermal sediments around the world. The microbes appear to be playing an important role in the global carbon cycle by helping break down decaying plants without producing the greenhouse gas methane.
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"Climate scientists should take these new microbes into account in their models to more accurately understand how they will impact climate change," said Brett Baker, assistant professor at The University of Texas at Austin's Marine Science Institute who led the research published April 23 in The new group, which biologists call a phylum, is named Brockarchaeota after Thomas Brock, a pioneer in the study of microbes that live in extreme environments such as the hot springs of Yellowstone National Park. Sadly, Brock died April 4. His research led to a powerful biotech tool called PCR, which is used, among other things, in gene sequencing and COVID-19 tests."The description of these new microbes from hot springs is a fitting tribute to Tom's legacy in microbiology," Baker added.So far, Brockarchaeota have not been successfully grown in a laboratory or imaged under a microscope. Instead, they were identified by painstakingly reconstructing their genomes from bits of genetic material collected in samples from hot springs in China and hydrothermal sediments in the Gulf of California. Baker and the team used high-throughput DNA sequencing and innovative computational approaches to piece together the genomes of the newly described organisms. The scientists also identified genes that suggest how they consume nutrients, produce energy and generate waste."When we looked in public genetic databases, we saw that they had been collected all around the world but described as 'uncultured microorganisms,'" said Valerie De Anda, first author of the new paper, referring to specimens collected by other researchers from hot springs in South Africa and Wyoming's Yellowstone, and from lake sediments in Indonesia and Rwanda. "There were genetic sequences going back decades, but none of them were complete. So, we reconstructed the first genomes in this phylum and then we realized, wow, they are around the world and have been completely overlooked."The Brockarchaeota are part of a larger, poorly studied group of microbes called archaea. Until now, scientists thought that the only archaea involved in breaking down methylated compounds -- that is, decaying plants, phytoplankton and other organic matter -- were those that also produced the greenhouse gas methane."They are using a novel metabolism that we didn't know existed in archaea," said De Anda. "And this is very important because marine sediments are the biggest reservoir of organic carbon on Earth. These archaea are recycling carbon without producing methane. This gives them a unique ecological position in nature."A phylum is a broad group of related organisms. To get a sense of just how large and diverse phyla are, consider that the phylum Chordata alone includes fish, amphibians, reptiles, birds, mammals and sea squirts. The phylum Arthropoda, which accounts for about 80% of all animals, includes insects, arachnids (such as spiders, scorpions and ticks) and crustaceans (crabs, lobsters, shrimp, and other tasty sea denizens).In July 2020, Baker, De Anda and others suggested the possible existence of several new phyla among the archaea, including Brockarchaeota, in a review article in In addition to breaking down organic matter, these newly described microbes have other metabolic pathways that De Anda speculates might someday be useful in applications ranging from biotechnology to agriculture to biofuels.
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Climate
| 2,021 |
April 25, 2021
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https://www.sciencedaily.com/releases/2021/04/210425114433.htm
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Climate has shifted the axis of the Earth, study finds
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Glacial melting due to global warming is likely the cause of a shift in the movement of the poles that occurred in the 1990s.
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The locations of the North and South poles aren't static, unchanging spots on our planet. The axis Earth spins around -- or more specifically the surface that invisible line emerges from -- is always moving due to processes scientists don't completely understand. The way water is distributed on Earth's surface is one factor that drives the drift.Melting glaciers redistributed enough water to cause the direction of polar wander to turn and accelerate eastward during the mid-1990s, according to a new study in "The faster ice melting under global warming was the most likely cause of the directional change of the polar drift in the 1990s," said Shanshan Deng, a researcher at the Institute of Geographic Sciences and Natural Resources Research at the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences and an author of the new study.The Earth spins around an axis kind of like a top, explains Vincent Humphrey, a climate scientist at the University of Zurich who was not involved in this research. If the weight of a top is moved around, the spinning top would start to lean and wobble as its rotational axis changes. The same thing happens to the Earth as weight is shifted from one area to the other.Researchers have been able to determine the causes of polar drifts starting from 2002 based on data from the Gravity Recovery and Climate Experiment (GRACE), a joint mission by NASA and the German Aerospace Center, launched with twin satellites that year and a follow up mission in 2018. The mission gathered information on how mass is distributed around the planet by measuring uneven changes in gravity at different points.Previous studies released on the GRACE mission data revealed some of the reasons for later changes in direction. For example, research has determined more recent movements of the North Pole away from Canada and toward Russia to be caused by factors like molten iron in the Earth's outer core. Other shifts were caused in part by what's called the terrestrial water storage change, the process by which all the water on land -- including frozen water in glaciers and groundwater stored under our continents -- is being lost through melting and groundwater pumping.The authors of the new study believed that this water loss on land contributed to the shifts in the polar drift in the past two decades by changing the way mass is distributed around the world. In particular, they wanted to see if it could also explain changes that occurred in the mid-1990s.In 1995, the direction of polar drift shifted from southward to eastward. The average speed of drift from 1995 to 2020 also increased about 17 times from the average speed recorded from 1981 to 1995.Now researchers have found a way to wind modern pole tracking analysis backward in time to learn why this drift occurred. The new research calculates the total land water loss in the 1990s before the GRACE mission started."The findings offer a clue for studying past climate-driven polar motion," said Suxia Liu, a hydrologist at the Institute of Geographic Sciences and Natural Resources Research at the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences and the corresponding author of the new study. "The goal of this project, funded by the Ministry of Science and Technology of China is to explore the relationship between the water and polar motion."Using data on glacier loss and estimations of ground water pumping, Liu and her colleagues calculated how the water stored on land changed. They found that the contributions of water loss from the polar regions is the main driver of polar drift, with contributions from water loss in nonpolar regions. Together, all this water loss explained the eastward change in polar drift."I think it brings an interesting piece of evidence to this question," said Humphrey. "It tells you how strong this mass change is -- it's so big that it can change the axis of the Earth."Humphrey said the change to the Earth's axis isn't large enough that it would affect daily life. It could change the length of day we experience, but only by milliseconds.The faster ice melting couldn't entirely explain the shift, Deng said. While they didn't analyze this specifically, she speculated that the slight gap might be due to activities involving land water storage in non-polar regions, such as unsustainable groundwater pumping for agriculture.Humphrey said this evidence reveals how much direct human activity can have an impact on changes to the mass of water on land. Their analysis revealed large changes in water mass in areas like California, northern Texas, the region around Beijing and northern India, for example -- all areas that have been pumping large amounts of groundwater for agricultural use."The ground water contribution is also an important one," Humphrey said. "Here you have a local water management problem that is picked up by this type of analysis."Liu said the research has larger implications for our understanding of land water storage earlier in the 20th century. Researchers have 176 years of data on polar drift. By using some of the methods highlighted by her and her colleagues, it could be possible to use those changes in direction and speed to estimate how much land water was lost in past years.
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Climate
| 2,021 |
April 22, 2021
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https://www.sciencedaily.com/releases/2021/04/210422123611.htm
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California's wildfire season has lengthened, and its peak is now earlier in the year
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California's wildfire problem, fueled by a concurrence of climate change and a heightened risk of human-caused ignitions in once uninhabited areas, has been getting worse with each passing year of the 21st century.
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Researchers in the Department of Civil & Environmental Engineering at the University of California, Irvine have conducted a thorough analysis of California Department of Forestry and Fire Protection wildfire statistics from 2000 to 2019, comparing them with data from 1920 to 1999. They learned that the annual burn season has lengthened in the past two decades and that the yearly peak has shifted from August to July. The team's findings are the subject of a study published today in the open-access journal The study is a focused examination of fire frequency, burned area and myriad drivers of the catastrophically destructive events. The team found that the number of hot spots -- places with severe fire risk -- has grown significantly in recent years, fueled by higher annual mean temperatures, greater vapor pressure deficit (lack of air moisture), drought, and an elevated chance of blazes being sparked through such human causes as power line disruptions, construction, transportation, campfires, discarded cigarettes and fireworks."CALFIRE data show that each new year of the 21st century has been a record breaker in terms of wildfire damage in California," said co-author Tirtha Banerjee, UCI assistant professor of civil & environmental engineering. "We also have seen that about 80 percent of the total number of the state's wildfires over the past few decades have been small, measuring less that 500 acres. But when fires get large, their deadliness greatly increases."Banerjee said that to gain a proper understanding of the growth of fire risk in California, it's important to put large and small incidents into separate buckets. By doing this, the team learned that 1,247 out of 6,336 wildfires, about 20 percent, accounted for 97 percent of the total burned area in the 2000 to 2020 period."And more than nine-tenths of the casualties and property losses can be attributed to fires exceeding the 500-acre threshold," Banerjee said.He added that over the past two decades, there has been a significant increase in "extreme" wildfires scorching more that 10,000 acres. Coinciding with that has been a rapid uptick in the frequency of small, human-caused blazes.One of the most alarming findings of the study, according to lead-author Shu Li, a Ph.D. student in Banerjee's laboratory, is the substantial spatial growth of fire risk throughout the state. From 1920 to 1999, California's only hot spot with "very high wildfire density" was Los Angeles County. In the past 20 years, that designation has expanded greatly in Southern California to include Ventura County, and portions of Riverside, San Diego and San Bernardino Counties.Even in northern California, areas known by fire managers as the Nevada-Yuba-Placer Unit and the Tuolumne-Calaveras Unit are newly emerged as high-density wildfire regions."Before 2000, there were almost no human-caused wildfires along California's Pacific coastline, but now nearly every coastal county is experiencing increased risk, and the San Benito-Monterey Unit and the San Luis Obispo Unit have even become new hot spots," said Li.Many of the major fires in the northern part of the state are naturally occurring, predominantly ignited by lightning. But the majority of the increase in fire probability in recent years can be blamed on an expansion of the wilderness-urban interface. As people move into previously unpopulated areas, they bring their bad fire management habits with them."The concurrence of human-caused climate change, which is drying out our forests and grasslands and creating longer stretches of hot weather, and a steady influx of people into remote areas is creating conditions for the perfect fire storm," said Banerjee. "But there is some good news in all of this; human-caused fire risk can be mitigated by better fire management practices by humans."He said he hoped the study and the near real-time analysis of fire risks in California's natural environment it provides can be used by government agencies and public policy officials to both prevent and combat costly blazes.
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Climate
| 2,021 |
April 22, 2021
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https://www.sciencedaily.com/releases/2021/04/210422102828.htm
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Unlocking Australia's biodiversity, one dataset at a time
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Australia's unique and highly endemic flora and fauna are threatened by rapid losses in biodiversity and ecosystem health, caused by human influence and environmental challenges. To monitor and respond to these trends, scientists and policy-makers need reliable data.
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Biodiversity researchers and managers often don't have the necessary information, or access to it, to tackle some of the greatest environmental challenges facing society, such as biodiversity loss or climate change. Data can be a powerful tool for the development of science and decision-making, which is where the Atlas of Living Australia (ALA) comes in.ALA -- Australia's national biodiversity database -- uses cutting-edge digital tools which enable people to share, access and analyse data about local plants, animals and fungi. It brings together millions of sightings as well as environmental data like rainfall and temperature in one place to be searched and analysed. All data are made publicly available -- ALA was established in line with open-access principles and uses an open-source code base.The impressive set of databases on Australia's biodiversity includes information on species occurrence, animal tracking, specimens, biodiversity projects, and Australia's Natural History Collections. The ALA also manages a wide range of other data, including information on spatial layers, indigenous ecological knowledge, taxonomic profiles and biodiversity literature. Together with its partner tools, the ALA has radically enhanced ease of access to biodiversity data. A forum paper recently published with the open-access, peer-reviewed Established in 2010 under the Australian Government's National Collaborative Research Infrastructure Strategy (NCRIS) to support the research sector with trusted biodiversity data, it now delivers data and related services to more than 80,000 users every year, helping scientists, policy makers, environmental planners, industry, and the general public to work more efficiently. It also supports the international community as the Australian node of the Global Biodiversity Information Facility and the code base for the successful international Living Atlases community.With thousands of records being added daily, the ALA currently contains nearly 95 million occurrence records of over 111,000 species, the earliest of them being from the late 1600s. Among them, 1.7 million are observation records harvested by computer algorithms, and the trend is that their share will keep growing.Recognising the potential of citizen science for contributing valuable information to Australia's biodiversity, the ALA became a member of the iNaturalist Network in 2019 and established an Australian iNaturalist node to encourage people to submit their species observations. Projects like DigiVol and BioCollect were also born from ALA's interest in empowering citizen science.The ALA BioCollect platform supports biodiversity-related projects by capturing both descriptive metadata and raw primary field data. BioCollect has a strong citizen science emphasis, with 524 citizen science projects that are open to involvement by anyone. The platform also provides information on projects related to ecoscience and natural resource management activities.Hosted by the Australian Museum, DigiVol is a volunteer portal where over 6,000 public volunteers have transcribed over 800,000 specimen labels and 124,000 pages of field notes. Harnessing the power and passion of volunteers, the tool makes more information available to science by digitising specimens, images, field notes and archives from collections all over the world.Built on a decade of partnerships with biodiversity data partners, government departments, community and citizen science organisations, the ALA provides a robust suite of services, including a range of data systems and software applications that support both the research sector and decision makers. Well regarded both domestically and internationally, it has built a national community that is working to improve the availability and accessibility of biodiversity data.
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421200127.htm
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Warming seas might also look less colorful to some fish: Here's why that matters
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When marine biologist Eleanor Caves of the University of Exeter thinks back to her first scuba dives, one of the first things she recalls noticing is that colors seem off underwater. The vivid reds, oranges, purples and yellows she was used to seeing in the sunlit waters near the surface look increasingly dim and drab with depth, and before long the whole ocean loses most of its rainbow leaving nothing but shades of blue.
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"The thing that always got me about diving was what happens to people's faces and lips," said her former Ph.D. adviser Sönke Johnsen, a biology professor at Duke University. "Everybody has a ghastly sallow complexion."Which got the researchers to thinking: In the last half-century, some fish have been shifting into deeper waters, and climate change is likely to blame. One study found that fish species off the northeastern coast of the United States descended more than one meter per year between 1968 and 2007, in response to a warming of only about one degree Celsius.Could such shifts make the color cues fish rely on for survival harder to see?Previous research suggests it might. Scientists already have evidence that fish have a harder time discerning differences in each other's hues and brightness in waters made murkier by other causes, such as erosion or nutrient runoff.As an example, the authors cite studies of three-spined sticklebacks that breed in the shallow coastal waters of the Baltic Sea, where females choose among males -- who care for the eggs -- based on the redness of their throats and bellies. But algal blooms can create cloudy conditions that make it harder to see, which tricks females into mating with less fit males whose hatchlings don't make it.The turbidity makes it harder for a male to prove he's a worthy mate by interfering with females' ability to distinguish subtle gradations of red or orange, Johnsen said. "For any poor fish that has beautiful red coloration on his body, now it's like, 'well, you're just going to have to take my word for it.'"Other studies have shown that, for cichlid fish in Africa's Lake Victoria, where species rely on their distinctive colors to recognize their own kind, pollution can reduce water clarity to a point where they lose the ability to tell each other apart and start mating every which way.The researchers say the same communication breakdown plaguing fish in turbid waters is likely happening to species that are being pushed to greater depths. And interactions with would-be mates aren't the only situations that could be prone to confusion. Difficulty distinguishing colors could also make it harder for fish to locate prey, recognize rivals, or warn potential predators that they are dangerous to eat.In a study published April 21 in the journal They were able to show that, while the surface waters may be bursting with color, descending by just 30 meters shrinks the palette considerably."It's like going back to the days of black and white TV," Johnsen said.When sunlight hits an object, some wavelengths are absorbed and others bounce off. It's the wavelengths that are reflected back that make a red fish look red, or a blue fish blue. But a fish sporting certain colors at the surface will start to look different as it swims deeper because the water filters out or absorbs some wavelengths sooner than others.The researchers were surprised to find that, especially for shallow-water species such as those that live in and around coral reefs, it doesn't take much of a downward shift to have a dramatic effect on how colors appear."You really don't have to go very far from the surface to notice a big impact," said Caves, who will be starting as an assistant professor at the University of California, Santa Barbara, this fall.Precisely which colors lose their luster first, and how quickly that happens as you go down, depends on what depths a species typically inhabits and how much deeper they are forced to go, as well as the type of environment they live in -- whether it's, say, the shallow bays or rocky shores of the Atlantic, or a tropical coral reef.In clear ocean water, red is the first color to dull and disappear. "That's important because so many species use red signals to attract mates or deter enemies," Johnsen said.The team predicts that some species will be more vulnerable than others. Take, for instance, fish that can't take the edge off the heat by relocating toward the poles of the planet. Particularly in semi-enclosed waters such as the Mediterranean and Black seas or the Gulf of Mexico, or in coral reefs, which are stuck to the sea bed -- these species will have no option but to dive deeper to keep their cool, Caves said.As a next step, they hope to test their ideas in the coral reefs around the island of Guam, where butterflyfishes and fire gobies use their vivid color patterns to recognize members of their own species and woo mates."The problem is only accelerating," Caves said. By the end of this century, it's possible that sea surface temperatures will have heated up another 4.8 degrees Celsius, or an increase of 8.6 degrees Fahrenheit, compared to the 1896-2005 average.And while warming is happening faster at the poles, "tropical waters are feeling the effects too," Caves said.This research was supported by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement (No 793454).
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421160016.htm
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Why climate change is driving some to skip having kids
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When deciding whether to have children, there are many factors to consider: finances, support systems, personal values. For a growing number of people, climate change is also being added to the list of considerations, says a University of Arizona researcher.
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Sabrina Helm, an associate professor in the Norton School of Family and Consumer Sciences in the College of Agriculture and Life Sciences, is lead author of a new peer-reviewed study that looks at how climate change is affecting people's decisions about whether to have children."For many people, the question of whether to have children or not is one of the biggest they will face in their lives," Helm said. "If you are worried about what the future will look like because of climate change, obviously it will impact how you view this very important decision in your life."Helm and her collaborators wanted to better understand the specific climate change-related reasons people have for not wanting to have children. They started by analyzing online comments posted in response to news articles written about the growing trend of people forgoing having children due to climate change concerns.They then sought out adults ages 18 to 35 who said climate change plays an important role in their reproductive decision-making. They interviewed 24 participants about their concerns.The researchers' findings, published in the journal Population and Environment, identify three major themes that emerged in both the online comments and the interviews.1) Overconsumption. This was the most common concern expressed by interviewees, Helm said. Almost all participants said they worried about how children would contribute to climate change through an increased carbon footprint and overuse of resources that could become more scarce in the future, such as food and water.2) Overpopulation. Overpopulation was the prevailing concern among online commenters, and it often came up in interviews as well, Helm said. Some participants said they felt having more than two children would be problematic and even selfish, as they would be "over-replacing" themselves and their partner. Some said they saw adoption as a more responsible choice. "Adoption was seen as the low-carbon alternative," Helm said.3) An uncertain future. Interviewees and online commenters also frequently expressed a sense of doom about the future if climate change continues unchecked. Many said they would feel guilty or as if they were doing something morally or ethically wrong if they brought a child into a world with such an uncertain future.While the "doom" perspective was prevalent, it was also balanced with expressions of hope, Helm said. Some interviewees and commenters said the very idea of children gives hope for a better and brighter future. Others expressed hope that future generations could contribute to environmental improvement by increasing climate change awareness and action."There was a hope that future generations will get the job done and makes things better," Helm said. "But that puts a lot of burden on small children."Understanding how climate change affects reproductive decision-making is part of a larger effort by Helm and other researchers to understand how climate change is impacting individuals mentally and emotionally overall. Helm noted that climate change anxiety is on the rise, especially in younger people."Many people now are severely affected in terms of mental health with regard to climate change concerns," she said. "Then you add this very important decision about having kids, which very few take lightly, and this is an important topic from a public health perspective. It all ties into this bigger topic of how climate change affects people beyond the immediate effect of weather phenomena."Helm said many study participants expressed anger and frustration that their concerns aren't taken seriously by family members and friends, who might dismissively tell them they will change their minds about having kids when they're older or meet the right person."It's still a bit taboo to even talk about this -- about how worried they are -- in an environment where there are still people who deny climate change," Helm said. "I think what's been lacking is the opportunity to talk about it and hear other people's voices. Maybe this research will help."
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421151258.htm
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Using floodwaters to weather droughts
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Floodwaters are not what most people consider a blessing. But they could help remedy California's increasingly parched groundwater systems, according to a new Stanford-led study. The research, published in
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"This is the first comprehensive assessment of floodwater recharge potential in California under climate change," said study lead author Xiaogang He, an assistant professor in civil and environmental engineering at the National University of Singapore who pursued the research as a postdoctoral fellow at Stanford's Program on Water in the West.Whether it's rivers overflowing in the Central Valley flatlands, high-tide storms hitting lowland coastal areas, flash floods drenching southern deserts or impermeable concrete-laden cities pooling with water, California is susceptible to flooding. Alternately, looming droughts often raise concern about water supply, as diminished groundwater sinks land, contaminates drinking water and reduces surface supplies. These declining reserves also hamper climate resilience -- during periods of drought up to 60 percent of the state's water comes from groundwater and 85 percent of Californians depend on the resource for at least a portion of their water supply.As climate change intensifies the severity and frequency of these extreme events, amplifying refill rates could help the state reach a more balanced groundwater budget. One practice, called water banking or managed aquifer recharge, involves augmenting surface infrastructure, such as reservoirs or pipelines, with underground infrastructure, such as aquifers and wells, to increase the transfer of floodwater for storage in groundwater basins.A newer strategy for managing surface water, compared to more traditional methods like reservoirs and dams, water banking poses multiple benefits including flood risk reduction and improved ecosystem services. While groundwater basins offer a vast network for water safekeeping, pinpointing areas prime for replenishment, gauging infrastructure needed and the amount of water available remains key, especially in a warming and uncertain climate."Integrating managed aquifer recharge with floodwaters into already complex water management infrastructure offers many benefits, but requires careful consideration of uncertainties and constraints. Our growing understanding of climate change makes this an opportune time to examine the potential for these benefits," said senior author David Freyberg, an associate professor of civil and environmental engineering at Stanford.The researchers designed a framework to estimate future floodwater availability across the state. Developing a hybrid computer model using hydrologic and climate simulations and statistical tools, the team calculated water available for recharge under different climate change scenarios through 2090. They also identified areas where infrastructure investments should be prioritized to tap floodwater potential and increase recharge.The team found California will experience increased floodwater from both heavier rain patterns and earlier snowmelt due to warmer temperatures, under a narrowing window of concentrated wet weather. In particular, the Sacramento River and North Coast, along with the northern and central Sierra Nevada region, will see more substantial floodwater volumes. These deluges could overload current water infrastructure, such as reservoirs and aqueducts. However, if the region is standing ready with additional floodwater diversion infrastructure, such as canals or pipelines, it could maximize recharge potential and transfer more of it toward arid Southern California.Future projections find unchanging or in some cases even drier conditions in Southern California. This widening divide is bad news for the region, which currently has greater groundwater depletion and recharge needs than its northern counterpart. This mismatch of water abundance and need reveals a profound challenge for recharge practices, in terms of moving high volumes of water from where it will be available in Northern California to where it will be needed southward.The researchers also found recharge estimates for the San Joaquin Valley -- one of the world's most productive agricultural regions -- could help restock a large portion of depleted groundwater aquifers. Sitting at the base of the Sierra Nevada mountains, this region will need to accommodate larger volumes of water both above and below the surface in order to maximize refill potential. Water managers will need to expand conveyance projects and reopen reservoirs there.While climate impacts are the most dominant influence, the researchers point out that other factors, including infrastructure capacity, policy constraints, financial and environmental concerns must be jointly considered during the planning process.The study's framework is adaptable and scalable for managing drought, flood and depleted groundwater aquifers worldwide."At the global scale only 1 percent of groundwater recharge occurs from managed aquifer recharge," He said. "This work can be applied to help other depleted aquifers, such as the North China Plain or India's Upper Ganges, reach and maintain sustainable groundwater levels."
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421151254.htm
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Carbon dioxide-rich liquid water in ancient meteorite
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By studying ancient meteorite fragments, scientists can gain important insights into how our solar system formed eons ago. Now, in a new study, researchers have discovered carbon dioxide-rich liquid water inside a meteorite from an asteroid that formed 4.6 billion years ago. This finding suggests that the meteorite's parent asteroid formed beyond Jupiter's orbit before being transported into the inner solar system and provides key evidence for the dynamics of the Solar System's formation.
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Water is abundant in our solar system. Even outside of our own planet, scientists have detected ice on the moon, in Saturn's rings and in comets, liquid water on Mars and under the surface of Saturn's moon Enceladus, and traces of water vapor in the scorching atmosphere of Venus. Studies have shown that water played an important role in the early evolution and formation of the solar system. To learn more about this role, planetary scientists have searched for evidence of liquid water in extraterrestrial materials such as meteorites, most of which originate from asteroids that formed in the early history of the solar system.Scientists have even found water as hydroxyls and molecules in meteorites in the context of hydrous minerals, which are basically solids with some ionic or molecular water incorporated within them. Dr. Akira Tsuchiyama, Visiting Research Professor at Ritsumeikan University, says, "Scientists further expect that liquid water should remain as fluid inclusions in minerals that precipitated in aqueous fluid" (or, to put it simply, formed from drops of water that contained various other things dissolved inside them). Scientists have found such liquid water inclusions inside salt crystals located within a class of meteorites known as ordinary chondrites, which represent the vast majority of all meteorites found on Earth though the salt actually originated from other, more primitive parent objects.Prof. Tsuchiyama and his colleagues wanted to know whether liquid water inclusions are present in a form of calcium carbonate known as calcite within a class of meteorites known as "carbonaceous chondrites," which come from asteroids that formed very early in the history of the solar system. They therefore examined samples of the Sutter's Mill meteorite, a carbonaceous chondrite originating in an asteroid that formed 4.6 billion years ago. The results of their investigation, led by Prof. Tsuchiyama, appear in an article recently published in The researchers used advanced microscopy techniques to examine the Sutter's Mill meteorite fragments, and they found a calcite crystal containing a nanoscale aqueous fluid inclusion that contains at least 15% carbon dioxide. This finding confirms that calcite crystals in ancient carbonaceous chondrites can indeed contain not only liquid water, but also carbon dioxide.The presence of liquid water inclusions within the Sutter's Mill meteorite has interesting implications concerning the origins of the meteorite's parent asteroid and the early history of the solar system. The inclusions likely occurred due to the parent asteroid forming with bits of frozen water and carbon dioxide inside of it. This would require the asteroid to have formed in a part of the solar system cold enough for water and carbon dioxide to freeze, and these conditions would place the site of formation far outside of Earth's orbit, likely beyond even the orbit of Jupiter. The asteroid must then have been transported to the inner regions of the solar system where fragments could later collide with the planet Earth. This assumption is consistent with recent theoretical studies of the solar system's evolution that suggest that asteroids rich in small, volatile molecules like water and carbon dioxide formed beyond Jupiter's orbit before being transported to areas closer to the sun. The most likely cause of the asteroid's transportation into the inner solar system would be the gravitational effects of the planet Jupiter and its migration.In conclusion, the discovery of water inclusions within a carbonaceous chondrite meteorite from the early history of the solar system is an important achievement for planetary science. Prof. Tsuchiyama proudly notes, "This achievement shows that our team could detect a tiny fluid trapped in a mineral 4.6 billion years ago."By obtaining chemical snapshots of an ancient meteorite's contents, his team's work can provide important insights into processes at work in the solar system's early history.
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421124640.htm
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Climate 'tipping points' need not be the end of the world
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The disastrous consequences of climate "tipping points" could be averted if global warming was reversed quickly enough, new research suggests.
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Once triggered, tipping points may lead to abrupt changes such as the dieback of the Amazon rainforest or melting of major ice sheets.Until now, crossing these thresholds has been assumed to be a point of no return, but the new study -- published in the journal The research team, from the University of Exeter and the UK Centre for Ecology and Hydrology (UKCEH), say the time available to act would depend on the level of global warming and the timescale involved in each tipping point."The more extreme the warming, the less time we would have to prevent tipping points," said lead author Dr Paul Ritchie, of Exeter's Global Systems Institute and the Department of Mathematics."This is especially true for fast-onset tipping points like Amazon forest dieback and disruption to monsoons, where irreversible change could take place in a matter of decades."Slow-onset tipping points take place over a timescale of many centuries and -- depending on the level of warming -- this would give us more time to act."Joe Clarke, also of the University of Exeter, said: "Fortunately, the tipping points that are believed to be closest are slow-onset tipping points. This may give us a lifeline to avoid dangerous climate change."Concerns about tipping points like Greenland ice sheet melt are one of the reasons for the Paris Agreement targets to keep global warming below 1.5°C."However, current rates of warming make it almost inevitable that we will exceed that level," said Professor Peter Cox.Dr Ritchie added: "It is widely assumed that this means we are now committed to suffering these tipping events."We show that this conventional wisdom may be flawed, especially for slow-onset tipping elements such as a collapse of the Atlantic Meridional Overturning Circulation or the melting of ice sheets."The "time to act" was calculated as the time taken to reverse warming and stabilise at 1.5°C above pre-industrial levels."Ideally, we will not cross tipping point thresholds, but this gives hope we may be able to pull back from danger if needed," said Dr Chris Huntingford of UKCEH.
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421124630.htm
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In calculating the social cost of methane, equity matters
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What is the cost of 1 ton of a greenhouse gas? When a climate-warming gas such as carbon dioxide or methane is emitted into the atmosphere, its impacts may be felt years and even decades into the future -- in the form of rising sea levels, changes in agricultural productivity, or more extreme weather events, such as droughts, floods, and heat waves. Those impacts are quantified in a metric called the "social cost of carbon," considered a vital tool for making sound and efficient climate policies.
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Now a new study by a team including researchers from Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley reports that the social cost of methane -- a greenhouse gas that is 30 times as potent as carbon dioxide in its ability to trap heat -- varies by as much as an order of magnitude between industrialized and developing regions of the world.Published recently in the journal "The paper broadly supports the previous U.S. government estimates of the social cost of methane, but if you use the number the way it's typically used -- as a global estimate, as if all countries are equal -- then it doesn't account for the inequities," said Berkeley Lab scientist William Collins, one of the study's co-authors.The lead authors of the study were David Anthoff, a professor in UC Berkeley's Energy and Resources Group, and Frank Errickson, a graduate student in the group at the time of the study. "The Biden administration's climate policy agenda calls for prioritizing environmental justice and equity. We provide a way for them to directly incorporate concerns for equity in methane emission regulations," said Errickson, now a postdoctoral fellow at Princeton University. "Our results capture that the same climate impact, when measured in dollars, causes a greater loss in well-being for low-income regions relative to wealthy ones."Like the social cost of carbon, the social cost of methane is a metric that is not widely used by the public but is increasingly used by government agencies and corporations in making decisions around policies and capital investments. By properly accounting for future damages that may be caused by greenhouse gas emissions, policymakers can weigh present costs against future avoided harms. In fact, the recent White House executive order on the climate crisis established a working group to provide an accurate accounting of the social costs of carbon, methane, and nitrous oxide within a year."President Biden's action represents a much-needed return of science-based policy in the United States," said Anthoff. "Devastating weather events and wildfires have become more common, and the costs of climate impacts are mounting.""The social costs of methane and carbon dioxide are used directly in cost-benefit analyses all the time," Collins said. "You have to figure out how to maximize the benefit from a dollar spent on mitigating methane emissions, as opposed to any of the other ways in which one might choose to spend that dollar. You want to make sure that you are not using a gold-plated band-aid."Given the current estimate of global methane emissions of 300 million metric tons per year, that puts the annual social cost of methane at nearly $300 billion, said Collins, the head of Berkeley Lab's Climate and Ecosystem Sciences Division and also a professor in UC Berkeley's Earth and Planetary Science Department. "Wet areas will get wetter and dry areas dryer, so there's an increase in severity of storms and droughts," he said. "The cost would include all the things that flow from that, such as infrastructure damaged, increased expenditures around keeping places cool, health risks associated with heat, and so on."While some methane comes from natural sources -- mostly wetlands -- about 60% of methane emissions come from human activity, including agriculture, fossil fuel production, landfills, and livestock production. It is considered a short-lived climate pollutant, staying in the atmosphere for only a decade or so, compared to more than 100 years for carbon dioxide."Given its potency as a greenhouse gas, regulating emissions of methane has long been recognized as critical component for designing an economically efficient climate policy," said Anthoff. "Our study updates the social cost of methane estimates and fills a critical gap in determining social costs."Under the Obama administration, the price was estimated at about $1,400 per metric ton. The Berkeley researchers made a technical correction in accounting for offsetting influences on the climate system, arriving at global mean estimate of $922 per metric ton. "We're suggesting they slightly overestimated it," Collins said.But more importantly, the uncertainty around the social cost of methane comes more from the social side, not the physics. "As a climate scientist, we've been busy trying to improve our estimates of the warming caused by methane," Collins said. "But it turns out the physics side is no longer the major source of uncertainty in the social cost of methane. It's now moved to the socio-economic sector, accounting for the damages and inequities."How societies choose to develop in the future -- such as expanding cities along coastlines or areas prone to flooding or wildfires, or moving away from such areas -- are a big unknown. "If we choose mitigate climate change more aggressively, the social cost of methane drops drastically," Collins said."Continuing our work to further explore the relationship between climate change and socioeconomic uncertainties -- not to mention the complex but important issues that arise when we account for equity -- is a promising area for future research and policy exploration," said Anthoff.Other study co-authors were Klaus Keller and Vivek Srikrishnan of The Pennsylvania State University. The research was supported by the National Science Foundation, the Sloan Foundation, and the Penn State Center for Climate Risk Management.
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421124544.htm
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Research team argues for combining organic farming and genetic engineering
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For more sustainability on a global level, EU legislation should be changed to allow the use of gene editing in organic farming. This is what an international research team involving the Universities of Bayreuth and Göttingen demands in a paper published in the journal
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In May 2020, the EU Commission presented its "Farm-to-Fork" strategy, which is part of the "European Green Deal." The aim is to make European agriculture and its food system more sustainable. In particular, the proportion of organic farming in the EU's total agricultural land is to be increased to 25 percent by 2030. However, if current EU legislation remains in place, this increase will by no means guarantee more sustainability, as the current study by scientists from Bayreuth, Göttingen, Düsseldorf, Heidelberg, Wageningen, Alnarp, and Berkeley shows.Numerous applications derived from new biotechnological processes are severely restricted or even banned by current EU law. This is especially true for gene editing, a new precision tool used in plant breeding. "Expanding organic farming further under the current legal restrictions on biotechnology could easily lead to less sustainability instead of more. Yet gene editing in particular offers great potential for sustainable agriculture," says Kai Purnhagen, lead author of the study and Professor of German & European Food Law at the University of Bayreuth.Organic farming focuses on greater farming diversity and prohibits the use of chemical fertilisers and pesticides. Therefore, it can have a beneficial effect on environmental protection and biodiversity at the local level. However, compared to conventional farming, organic farming also delivers lower yields. Consequently, more land is needed to produce the same amount of high-quality food. "As global demand for high-quality food increases, more organic farming in the EU would lead to an expansion of agricultural land elsewhere in the world. This could easily result in environmental costs that exceed any local environmental benefits in the EU, as the conversion of natural land into agricultural land is one of the biggest drivers of global climate change and biodiversity loss," says co-author Matin Qaim, Professor of Agricultural Economics at the University of Göttingen.The combination of organic farming and modern biotechnology could be a way to resolve this dilemma. "Gene editing offers unique opportunities to make food production more sustainable and to further improve the quality, but also the safety, of food. With the help of these new molecular tools, more robust plants can be developed that deliver high yields for high-quality nutrition, even with less fertiliser," says co-author Stephan Clemens, Professor of Plant Physiology at the University of Bayreuth and founding Dean of the new Faculty of Life Sciences: Food, Nutrition & Health on the Kulmbach campus. In addition, gene editing is used to breed fungus-resistant plants that thrive under organic farming without copper-containing pesticides. Copper is particularly toxic to soil and aquatic organisms, but its use to control fungi is nevertheless permitted in organic farming because of the lack of non-chemical alternatives to date. "Organic farming and gene editing could therefore complement each other very well and, combined, could contribute to more local and global sustainability," says Qaim.However, the use of genetic engineering in organic farming requires legal changes at the EU level. "There is certainly no political majority for this at present, because genetic engineering is viewed very critically by many. Yet perhaps improved communication could gradually lead to greater societal openness, at least towards gene editing, because this form of genetic engineering enables very targeted breeding without having to introduce foreign genes into the plants. Highlighting this point could dispel many of the widespread fears of genetic engineering," says Purnhagen.
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Climate
| 2,021 |
April 21, 2021
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https://www.sciencedaily.com/releases/2021/04/210421124535.htm
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Solar panels are contagious - but in a good way
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The number of solar panels within shortest distance from a house is the most important factor in determining the likelihood of that house having a solar panel, when compared with a host of socio-economic and demographic variables. This is shown in a new study by scientists using satellite and census data of the city of Fresno in the US, and employing machine learning. Although it is known that peer effects are relevant for sustainable energy choices, very high-resolution data combined with artificial intelligence techniques were necessary to single out the paramount importance of proximity. The finding is relevant for policies that aim at a broad deployment of solar panels in order to replace unsustainable fossil fueled energy generation.
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"It's almost like if you see a solar panel from out of your window, you decide to put one on your own roof as well," says study author Leonie Wenz from the Potsdam Institute for Climate Impact Research (PIK) in Germany. "Of course, one might think that other factors are more relevant, for instance income or educational background, or word-of-mouth within the same social network such as a school district. So we compared all these different options, and we've been amazed by the outcome. It turns out that, no, geographical distance really is the most important factor. The more panels there are within a short radius around my house, the more likely I'm of having one, too.""The likelihood of putting a solar panel on your roof roughly halves over the distance of a football field," says Anders Levermann from PIK and Columbia University's LDEO in New York who is also an author of the study. "The contagion effect is strongest for a short radius around a home with a solar panel and decreases exponentially the farther away the panels are. It is a remarkable robust feature that is most pronounced in low-income neighborhoods.The scientists just made the data speak. "We combined population census data for every district with high-resolution satellite data that is able to identify all the solar panels in Fresno," explains study author Kelsey Barton-Henry from PIK. "Then we trained several machine learning algorithms to find the relation between people's socio-economic setting and their likelihood of having a solar panel.""The findings suggest that seeding solar panels in areas where few exist, may flip a community," concludes Levermann. "If more solar panels lead to more solar panels that may generate a kind of tipping point -- a good one this time. The climate system has a number of extremely dangerous tipping points from the West Antarctic ice sheet to the North Atlantic Current." Wenz adds: "Hence, researching climate decisions to identify positive social tipping points, both small and big ones, is important to ensure a safe tomorrow for all."
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Climate
| 2,021 |
April 20, 2021
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https://www.sciencedaily.com/releases/2021/04/210420160901.htm
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'Dead clades walking': Fossil record provides new insights into mass extinctions
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Mass extinctions are known as times of global upheaval, causing rapid losses in biodiversity that wipe out entire animal groups. Some of the doomed groups linger on before going extinct, and a team of scientists found these "dead clades walking" (DCW) are more common and long-lasting than expected.
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"Dead clades walking are a pattern in the fossil record where some animal groups make it past the extinction event, but they also can't succeed in the aftermath," said Benjamin Barnes, a doctoral student in geosciences at Penn State. "It paints the pictures of a group consigned to an eventual extinction."The scientists found 70 of the 134 orders of ancient sea-dwelling invertebrates they examined could be identified as DCW in a new statistical analysis of the fossil record."What really fascinated us was that over half of all the orders we looked at have this phenomenon and that it can look like many different things," said Barnes, who led a group of graduate students and a postdoctoral researcher on the study. "In some cases, you have a group that has a sudden drop in diversity and lasts for a few more million years before disappearing from the record. But we also found many orders straggled along sometimes for tens or hundreds of millions of years."The findings, published in the journal "I think it raises questions about how the so-called kill mechanism operates," Barnes said. "We think of mass extinctions as being these selective forces that cause large groups of animals to go extinct, but our results really show there are a lot of instances where it's not so sudden. It raises questions about why that's such a long delay."Paleontologist David Jablonski first coined the term DCW more than 20 years ago, and since then it has been associated almost exclusively with mass extinctions. Using a wealth of new fossil record data made available over the last two decades, the study found DCW are also common around smaller, more localized background extinction stages, the scientists said."Our results suggest that rather than representing a rare, brief fossil pattern in the wake of mass extinction events, DCWs are actually a really diverse phenomenon and that there might be a lot of drivers that produce this pattern in the fossil record," Barnes said. "These DCWs may represent a major macroevolutionary pattern."The scientists used a statistical technique called a Bayesian change point algorithm to analyze fossil records from the Paleobiology Database, a public record of paleontological data maintained by international scientists.The method allowed the researchers to search time series data for significant points where the data deviated from the pattern. They were able to identify negative jagged shifts in diversity and rule out that the organism went extinct immediately but instead persisted."So you might be looking in the fossil record and you'll find tons of a type of brachiopod," Barnes said. "Each order has a handful of families and dozens of genera within those families. Then you might see a drop in diversity, and the majority of those genera disappear and perhaps there's only one family that continues to survive."Those survivors can continue in their niche for millions of years, even into the present. But their lack of diversity makes them more susceptible to future environmental challenges or extinction events, the scientists said."I think these findings cause you to reexamine how you measure success," Barnes said. "It's quite possible for an animal group not to produce new families and new genera at a rate like it did before, but if it continues to survive for many millions of years, that's still some form of success. I think it raises a lot of questions about what it means to be successful as a fossil organism and what ultimately are the controls of origination."
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Climate
| 2,021 |
April 20, 2021
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https://www.sciencedaily.com/releases/2021/04/210420121506.htm
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New catalyst for lower CO2 emissions
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If the CO
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At TU Wien, research is being conducted on a special class of minerals -- the perovskites, which have so far been used for solar cells, as anode materials or electronic components rather than for their catalytic properties. Now scientists at TU Wien have succeeded in producing a special perovskite that is excellently suited as a catalyst for converting CO"We are interested in the so-called reverse water-gas shift reaction," says Prof. Christoph Rameshan from the Institute of Materials Chemistry at TU Wien. "In this process, carbon dioxide and hydrogen are converted into water and carbon monoxide. You can then process the carbon monoxide further, for example into methanol, other chemical base materials or even into fuel."This reaction is not new, but it has not really been implemented on an industrial scale for COChristoph Rameshan and his team investigated how to tailor a material from the class of perovskites specifically for this reaction, and he was successful: "We tried out a few things and finally came up with a perovskite made of cobalt, iron, calcium and neodymium that has excellent properties," says Rameshan.Because of its crystal structure, the perovskite allows certain atoms to migrate through it. For example, during catalysis, cobalt atoms from the inside of the material travel towars the surface and form tiny nanoparticles there, which are then particularly chemically active. At the same time, so-called oxygen vacancies form -- positions in the crystal where an oxygen atom should actually sit. It is precisely at these vacant positions that CO"We were able to show that our perovskite is significantly more stable than other catalysts," says Christoph Rameshan. "It also has the advantage that it can be regenerated: If its catalytic activity does wane after a certain time, you can simply restore it to its original state with the help of oxygen and continue to use it."Initial assessments show that the catalyst is also economically promising. "It is more expensive than other catalysts, but only by about a factor of three, and it is much more durable," says Rameshan. "We would now like to try to replace the neodymium with something else, which could reduce the cost even further."Theoretically, you could use such technologies to get CO
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Climate
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April 20, 2021
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https://www.sciencedaily.com/releases/2021/04/210420121446.htm
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Ten ways to ensure bees benefit from the solar power boom
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Researchers assessing the impact of solar energy development across Europe have come up with ten ways in which the expansion of solar can be shaped to ensure pollinators benefit.
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Space-hungry solar photovoltaic (PV) is set to dominate future global electricity supply, but with careful decision making, efforts to secure clean energy need not come at the expense of biodiversity -- particularly pollinators which are in sharp decline.Bees, hoverflies, wasps, beetles, butterflies and moths play a key role in food production, with around 75% of the leading global food crops and 35% of global crop production relying on them to some extent.Writing in the journal Along with colleagues from the University of Reading, they highlighted ten evidence-based ways to protect and even enhance pollinator biodiversity ranging from sowing wildflowers to connecting solar parks to nearby areas of semi-natural habitat.Their findings are timely as, in a bid to tackle climate change and reduce greenhouse gas emissions, more power is being generated from renewable sources -- at the beginning of 2020 a record breaking 47% of the UK's electricity came from renewables, including wind, solar, hydro, wave and biomass.Solar parks can produce large amounts of power, with the UK's largest solar park set to power 91,000 homes once complete. But, solar parks also take up land, with potential impacts on the environment. In the UK approximately half of PV has been installed as ground-mounted solar parks, ranging in size from 1-40 hectares.Shading caused by rows of solar panels affects air temperature, rainfall and evaporation which has a knock on effect on soil, vegetation and biodiversity.However, in the UK solar parks are often built in intensively managed agricultural landscapes and thus are poor for biodiversity. In this scenario, solar parks may in fact provide opportunities to establish hotspots of pollinator biodiversity which in turn can help pollinate local crops such as oilseed, strawberries and apples.Lancaster University's Hollie Blaydes said: "Many pollinators are in decline both in the UK and in other parts of the world. Actions to conserve pollinators include reversing agricultural intensification and maintaining natural habitat, both of which can be achieved within solar parks. Often built amongst agricultural land, solar parks offer a unique opportunity to provide pollinator resources where they are most needed."Prof Simon Potts, University of Reading, said: "As well as promoting biodiversity, pollinator-friendly solar parks also have the potential to provide tangible economic benefits to farmers through enhancing pollination services to adjacent agricultural land, boosting crop yields."Imagine a world where solar parks not only produced much needed low carbon electricity but were also diverse and attractive wildflower meadows buzzing with insect life."Dr Alona Armstrong, Lancaster University Environment Centre said: "Land use change for solar parks could cause further degradation of our environment but, if done well, offers much potential to improve our environment. If we transition well, we could use energy system decarbonisation to also address the ecological crisis. Given where we are, can we afford not to?"Funded by NERC (ENVISION DTP), with support from Low Carbon, authors included Hollie Blaydes (Lancaster University), Dr Alona Armstrong (Lancaster University), Prof Simon Potts (University of Reading) and Prof Duncan Whyatt (Lancaster University)
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Climate
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April 20, 2021
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https://www.sciencedaily.com/releases/2021/04/210420121440.htm
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Oceanographers reveal links between migrating Gulf Stream and warming ocean waters
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The Northwest Atlantic Shelf is one of the fastest-changing regions in the global ocean, and is currently experiencing marine heat waves, altered fisheries and a surge in sea level rise along the North American east coast. A new paper, "Changes in the Gulf Stream preceded rapid warming of the Northwest Atlantic Shelf," published in
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"We used satellite data to show that when the Gulf Stream migrates closer to the underwater plateau known as the Grand Banks of Newfoundland, as it did after 2008, it blocks the southwestward transport of the Labrador Current that would otherwise provide cold, fresh, oxygen-rich water to the North American shelf," said lead author Gonçalves Neto. This mechanism explains why the most recent decade has been the hottest on record at the edge of the Northeast United States and Canada, as the delivery system of cold water to the region got choked off by the presence of the Gulf Stream.The URI research team noted the importance of finding that the satellite-observed signature of the Gulf Stream's position relative to the Grand Banks precedes subsurface shelf warming by over a year. "By monitoring satellite observations for changes near the Grand Banks, we can predict changes coming to the Northeast U.S. shelf with potentially enough lead time to inform fishery management decision-making," said GSO graduate student and co-author Joe Langan.The Grand Banks of Newfoundland is hardly a stranger to attention. It was near this feature that an iceberg sank the R.M.S. Titanic, one impetus for creation of the International Ice Patrol. The Ice Patrol has been collecting oceanographic data in this region for over a century, allowing the URI team to put recent satellite observations in a much longer-term context. Though the 2008 shift at the edge of the Grand Banks created warmer and saltier conditions than ever recorded since 1930, there was a similar shift in the 1970s relative to the decades preceding it. Thus, the circulation change directly observed by satellites might have had a precedent about 50 years ago.Jaime Palter, GSO associate professor of oceanography and co-author of the study, marveled at the long record, and what remains unknown. "We still don't know what caused the abrupt shift of the circulation near the Grand Banks inferred in the 1970s and observed in 2008, or whether this is the new normal for the circulation and the temperatures of the northeast shelf," said Palter. "There are modeling studies that suggest that a slowdown of the Atlantic Meridional Overturning Circulation can cause the types of changes we observed, but the connection remains to be made in the observational record."
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Climate
| 2,021 |
April 20, 2021
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https://www.sciencedaily.com/releases/2021/04/210420092858.htm
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Can extreme melt destabilize ice sheets?
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Nearly a decade ago, global news outlets reported vast ice melt in the Arctic as sapphire lakes glimmered across the previously frozen Greenland Ice Sheet, one of the most important contributors to sea-level rise. Now researchers have revealed the long-term impact of that extreme melt.
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Using a new approach to ice-penetrating radar data, Stanford University scientists show that this melting left behind a contiguous layer of refrozen ice inside the snowpack, including near the middle of the ice sheet where surface melting is usually minimal. Most importantly, the formation of the melt layer changed the ice sheet's behavior by reducing its ability to store future meltwater. The research appears in "When you have these extreme, one-off melt years, it's not just adding more to Greenland's contribution to sea-level rise in that year -- it's also creating these persistent structural changes in the ice sheet itself," said lead study author Riley Culberg, a PhD student in electrical engineering. "This continental-scale picture helps us understand what kind of melt and snow conditions allowed this layer to form."The 2012 melt season was caused by unusually warm temperatures exacerbated by high atmospheric pressure over Greenland -- an extreme event that may have been caused or intensified by climate change. The Greenland Ice Sheet has experienced five record-breaking melt seasons since 2000, with the most recent occurring in 2019."Normally we'd say the ice sheet would just shrug off weather -- ice sheets tend to be big, calm, slow things," said senior author Dustin Schroeder, an assistant professor of geophysics at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth). "This is really one of the first cases where you can say, shockingly, in some ways, these slow, calm ice sheets care a lot about a single extreme event in a particularly warm year."Shifting scenariosAirborne radar data, a major expansion to single-site field observations on the icy poles, is typically used to study the bottom of the ice sheet. But by pushing past technical and computational limitations through advanced modeling, the team was able to reanalyze radar data collected by flights from NASA's Operation IceBridge from 2012 to 2017 to interpret melt near the surface of the ice sheet, at a depth up to about 50 feet."Once those challenges were overcome, all of a sudden, we started seeing meltwater ice layers near the surface of the ice sheet," Schroeder said. "It turns out we've been building records that, as a community, we didn't fully realize we were making."Melting ice sheets and glaciers are the biggest contributors to sea-level rise -- and the most complex elements to incorporate into climate model projections. Ice sheet regions that haven't experienced extreme melt can store meltwater in the upper 150 feet, thereby preventing it from flowing into the ocean. A melt layer like the one from 2012 can reduce the storage capacity to about 15 feet in some parts of the Greenland Ice Sheet, according to the research.The type of melt followed by rapid freeze experienced in 2012 can be compared to wintry conditions in much of the world: snow falls to the ground, a few warm days melt it a little, then when it freezes again, it creates slick ice -- the kind that no one would want to drive on."The melt event in 2012 is impacting the way the ice sheet responds to surface melt even now," Culberg said. "These structural changes mean the way the ice sheet responds to surface melting is going to be impacted longer term."In the long run, meltwater that can no longer be stored in the upper part of the ice sheet may drain down to the ice bed, creating slippery conditions that speed up the ice and send chunks into the ocean, raising sea levels more quickly.Polar patternsGreenland currently experiences change much more rapidly than its South Pole counterpart. But lessons from Greenland may be applied to Antarctica when the seasons shift, Schroeder said."I think now there's no question that when you're trying to project into the future, a warming Antarctic will have all these processes," Schroeder said. "If we don't use Greenland now to better understand this stuff, our capacity to understand how a warmer world will be is not a hopeful proposition."The research was supported by a National Defense Science and Engineering Graduate Fellowship and the National Science Foundation (NSF).
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| 2,021 |
April 20, 2021
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https://www.sciencedaily.com/releases/2021/04/210420092855.htm
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Rock glaciers will slow Himalayan ice melt
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Some Himalayan glaciers are more resilient to global warming than previously predicted, new research suggests.
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Rock glaciers are similar to "true" ice glaciers in that they are mixtures of ice and rock that move downhill by gravity -- but the enhanced insulation provided by surface rock debris means rock glaciers will melt more slowly as temperatures rise.Rock glaciers have generally been overlooked in studies about the future of Himalayan ice.The new study, led by Dr Darren Jones at the University of Exeter, shows rock glaciers already account for about one twenty-fifth of Himalayan glacial ice -- and this proportion will rise as exposed glaciers continue to melt and some transition to become rock glaciers."Glaciers play a vital role in regulating water supplies, and Himalayan glaciers regulate water for hundreds of millions of people," said Professor Stephan Harrison, of the University of Exeter."Over the past century, these glaciers have lost about 25% of their mass due to climate change, and they are predicted to lose more in the future."However, glacier models have treated glaciers as uniform lumps of ice -- and our study shows not all glaciers will melt at the same rate."Many are covered in rock and are in various stages of the transition to rock glaciers."These slow-moving glaciers are well insulated, and as a result they are more resilient to global warming than 'true' glaciers."The study has provided the first estimate of the number and importance of rock glaciers in the Himalayas.It shows that there are about 25,000 rock glaciers in the region, containing a total of about 51 cubic kilometres of ice -- or 41-62 trillion litres of water.Despite this, lead author Dr Darren Jones cautioned: "Although we find that rock glaciers are more resilient to warming, it remains clear that all Himalayan glaciers are in long-term decline, with enormous implications for the people who rely on them for water supplies.""Further research into Himalayan rock glaciers is critical for underpinning climate change adaptation strategies and to ensure that this highly populated region is in a strong position to meet sustainable development goals," said Professor Richard Betts, of the Met Office Hadley Centre and the University of Exeter, who was also involved in the study.The research team included Dr Karen Anderson at the University of Exeter and Dr Sarah Shannon at the University of Bristol.Funders included the Natural Environment Research Council, GW4 PhD funding to Dr Darren Jones, and the BEIS/Defra Met Office Hadley Centre Climate Programme.The paper, published in the journal
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Climate
| 2,021 |
April 19, 2021
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https://www.sciencedaily.com/releases/2021/04/210419135717.htm
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Ocean currents modulate oxygen content at the equator
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A German-French study led by the GEOMAR Helmholtz Centre for Ocean Research Kiel has used long-term observations to investigate the complex interplay between fluctuations in the equatorial current system and variations in oxygen content. During the last 15 years the intensification of upper-ocean currents resulted in an increasing oxygen content in the equatorial region.
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Due to global warming, not only the temperatures in the atmosphere and in the ocean are rising, but also winds and ocean currents as well as the oxygen distribution in the ocean are changing. For example, the oxygen content in the ocean has decreased globally by about 2% in the last 60 years, particularly strong in the tropical oceans. However, these regions are characterized by a complex system of ocean currents. At the equator, one of the strongest currents, the Equatorial Undercurrent (EUC), transports water masses eastwards across the Atlantic. The water transport by the EUC is more than 60 times larger than that of the Amazon river. For many years, scientists at GEOMAR have been investigating in cooperation with the international PIRATA programme fluctuations of this current with fixed observation platforms, so-called moorings. Based on the data obtained from these moorings, they were able to prove that the EUC has strengthened by more than 20% between 2008 and 2018. The intensification of this major ocean current is associated with increasing oxygen concentrations in the equatorial Atlantic and an increase in the oxygen-rich layer near the surface. Such a thickening of the surface oxygenated layer represents a habitat expansion for tropical pelagic fish. The results of the study have now been published in the international journal "At first, this statement sounds encouraging, but it does not describe the entire complexity of the system," says project leader and first author Prof. Dr. Peter Brandt from GEOMAR. "We found that the strengthening of the Equatorial Undercurrent is mainly caused by a strengthening of the trade winds in the western tropical North Atlantic," Peter Brandt explains further. The analysis of a 60-year data set has shown that the recent oxygen increase in the upper equatorial Atlantic is associated with a multidecadal variability characterised by low oxygen concentrations in the 1990s and early 2000s and high concentrations in the 1960s and 1970s. "In this respect, our results do not contradict the global trend, but indicate that the observed current intensification likely will switch back into a phase of weaker currents associated with enhanced oxygen reduction. It shows the need for long-term observations in order to be able to separate natural fluctuations of the climate system from trends such as oxygen depletion caused by climate warming," says Brandt.The changes in oxygen supply in the tropics due to circulation fluctuations have an impact on marine ecosystems and ultimately on fisheries in these regions. "Habitat compression or expansion for tropical pelagic fish can lead to altered predator-prey relationships, but also make it particularly difficult to assess overfishing of economically relevant fish species, such as tuna," says Dr Rainer Kiko, co-author from the Laboratoire d'Océanographie de Villefranche at Sorbonne University, Paris.The investigations are based partly on a ship expedition carried out along the equator at the end of 2019 with the German research vessel METEOR. This expedition included a physical, chemical, biogeochemical and biological measurement programme that supports the development of climate-based predictions for marine ecosystems as part of the EU-funded TRIATLAS project. While another expedition with RV METEOR along the equator had to be cancelled due to the COVID-19 pandemic, several long-term moorings in the tropical Atlantic -- including the one at the equator -- will now be recovered and redeployed during an additional expedition with RV SONNE in June-August 2021, of course under strict quarantine conditions.
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Climate
| 2,021 |
April 19, 2021
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https://www.sciencedaily.com/releases/2021/04/210419110152.htm
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Ice cap study promises new prospects for accurate local climate projections
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New, detailed study of the Renland Ice Cap offers the possibility of modelling other smaller ice caps and glaciers with significantly greater accuracy than hitherto. The study combined airborne radar data to determine the thickness of the ice cap with on-site measurements of the thickness of the ice cap and satellite data. Researchers from the Niels Bohr Institute -- University of Copenhagen gathered the data from the ice cap in 2015, and this work has now come to fruition in the form of more exact predictions of local climate conditions.
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The accuracy of the study allows for the construction of models for other smaller ice caps and glaciers, affording significantly improved local projections of the condition of glaciers locally, around the globe. The results have recently been published in The initial, principal aim of the study, was to assess the thickness and volume of the Renland Ice Cap, and in the process, validate computer-modelled data against real data. Airborne radar, which measured the thickness of the ice, was compared with measurement results that were known in advance. In addition, researchers availed of satellite-based measurements of the ice velocity on the surface of the ice cap, again juxtaposed with various parameters entered into the computer model, e.g. "basal slide" -- in other words, the velocity of movement at the bottom of the ice cap. The combined results provided researchers with an extremely detailed basis material for constructing a computer model that can be applied in other situations.Iben Koldtoft, PhD student at the Physics of Ice, Climate and Earth section at the Niels Bohr Institute, and first author of the scientific article, explains: "We now have the most optimal parameters for this ice flow model, the Parallet Ice Sheet Model, for the Renland Ice Cap. But despite these being specific local measurements for Renland, we can use these modelling parameters to simulate the ice cap over an entire ice age cycle, for example, and compare the results with the Renland ice core we drilled in 2015. We can examine to what extent the ice cap has changed over time, or how quickly the ice will melt if the temperature rises by a few degrees in the future. Or put more concisely: We now know how the model can be "tuned" to match different climate scenarios. This ensures greater accuracy and a method that is also transferable to other smaller ice caps and glaciers.""In fact, we can see that our scientific article initially received many views from Japan and Argentina. At first this was a bit surprising -- why there, exactly? But it makes absolute sense. These are countries with smaller local ice sheets and glaciers, who are now excited to be able to project the future evolution of these," comments Iben Koldtoft.The larger ice sheets in Greenland and Antarctica are of course the most important, when assessing temperature changes and the effects of melting on global climate. However, the smaller ice caps react faster and can be considered as "mini- environments," where it is possible to follow developments across a shorter timescale. In addition, it is easier to model the smaller scenarios more precisely, points out Iben Koldtoft."If we look at Svalbard, an archipelago that lies very far north, they experience climate change as having a far greater local effect than one sees in Greenland, for example. Over time, of course, all these changes will eventually affect the entire climate system, but we can observe it more clearly on a smaller scale."In 2015 a core was drilled on the Renland Ice Cap. In the intervening years, scientists have extracted data from the recovered ice core in the form of water isotopes, gases and chemical measurements. These are all proxies for temperature, precipitation accumulation, altitude changes and other climate conditions of east Greenland, where the Renland Ice Cap is located. This data can now be compared with the detailed study and with data from other locations in Greenland. As a result, the study contributes to the increasingly detailed picture of how the climate is changing. Iben Koldtoft emphasises the importance of combining the observational data with computer modelling, and that climate research in general is at a stage where the use of advanced computer simulations and the ability to "tune" them correctly, is now a vital competence. Although glaciers across the globe can be monitored with incredible accuracy by satellites today, there is a need to develop strong computer-based models, combining physics and mathematics, in order to calculate how glaciers will change in the climate of the future, and their effect on future increases in sea levels.
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Climate
| 2,021 |
April 19, 2021
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https://www.sciencedaily.com/releases/2021/04/210419110146.htm
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Human land-use and climate change will have significant impact on animal genetic diversity
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Over the last 200 years, researchers have worked towards understanding the global distribution of species and ecosystems. But so far even the basic knowledge on the global geography of genetic diversity was limited.
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That now changes with a recent paper from Globe Institute. Professor David Nogues Bravo and his team has spent the last eight years combining data from scientific gene banks with scenarios of future climate and land-use change. The result is the first ever global assessment of how it will impact the genetic diversity of mammals, e.g. when tropical forests are converted to agricultural land.'Our study identifies both genetically poor and highly diverse areas severely exposed to global change, paving the way to better estimate the vulnerability to global change such as rise in temperature as well as land-use changes. It could help countries to find out how much of the genetic diversity in their own country may be exposed to different global change impacts, while also establishing priorities and conservation policies', says David Nogues Bravo.For example, Northern Scandinavia will be heavily impacted by climate change and not so much from land use change, whereas the tropical areas of the world will suffer from both climate change and land-use change. However, David Nogues Bravo underlines that it is difficult to compare areas.'The genetic diversity in Scandinavia is always going to be lower than in the tropics, but that doesn't mean that the overall diversity there is not important. If we lose populations and species such as the polar bear, it's just one species but it will it will impact the total stability of ecosystems. However, the largest threat to genetic diversity will be in the tropical areas, which currently harbor the largest diversity of the bricks of life, genes. These regions include ecosystems like mangroves, jungles and grasslands', says David Nogues Bravo.The researchers have looked into gene banks with mitochondrial data from mammals. The mitochondria also regulate the metabolism, and by looking how it has changed over time, it can also unveil changes in diversity.'The mitochondrial diversity is a broad estimate of adaptive capacity. We also used to think that mitochondria was a neutral marker, when it is in fact under selection. That means that some selection may relate to the physiological limits of a species in relation to climate, which makes it a very useful tool for researchers to track how global change impacts the genetic diversity in a specific area', explains David Nogues Bravo.For many samples, there were not any geographical information available. The researchers used artificial intelligence to add geographical locations and then they built models predicting how much genetic exits in places without data.Then the researchers analyzed maps of genetic diversity, future climate change and future land-use change, to reveal how and where global change will impact mammals.The research has attracted the attention of Secretariat of the United Nations Convention on Biological Diversity. David Nogues Bravo hope that the assessment map could become an important tool for the high-level summits among countries to help define policies for biodiversity protection.'We are only now starting to have the tools, data and knowledge to understand how genetic diversity changes across the globe. In a decade from now, we will be able to know also how much of that genetic diversity has been lost since the Industrial Revolution for thousands of species and in a stronger position to bring effective measures to protect it', he says.In the coming years, he hopes that scientists will map the global genetic diversity of many other forms of life, including plants, fungi and animals across the lands, rivers and oceans.'Have been attempts to map the genetic diversity for amphibians, birds and reptiles, but we don't have maps for plants, insects or fungi. And whereas there are around 5000 mammal species, there are many more insect or fungi species, maybe millions. We don't even know how many, yet. So it will take longer, but it will come in the next decade', he says.'We hope to see more of these assessments in the next decade, and to complement then with long-term monitoring programs, in which we can monitor the genetic diversity of thousands of species and ecosystems across the planet continually', says David Nogues Bravo.
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Climate
| 2,021 |
April 19, 2021
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https://www.sciencedaily.com/releases/2021/04/210419110134.htm
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Mountain high: Andean forests have high potential to store carbon under climate change
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The Andes Mountains of South America are the most species-rich biodiversity hotspot for plant and vertebrate species in the world. But the forest that climbs up this mountain range provides another important service to humanity.
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Andean forests are helping to protect the planet by acting as a carbon sink, absorbing carbon dioxide and keeping some of this climate-altering gas out of circulation, according to new research published in The study -- which draws upon two decades of data from 119 forest-monitoring plots in Colombia, Ecuador, Peru, Bolivia and Argentina -- was produced by an international team of scientists including researchers supported by the Living Earth Collaborative at Washington University in St. Louis. The lead author was Alvaro Duque from the Universidad Nacional de Colombia Sede Medellín."Based on the information that we have, Andean forests are a carbon sink -- capturing more carbon than they emit," said J. Sebastián Tello, a co-author of the study and a principal investigator for the Living Earth Collaborative working group titled, "A synthesis of patterns and mechanisms of diversity and forest change in the Andes: A global biodiversity hotspot.""The amount of carbon that is stored in the aboveground biomass in the stems and leaves of trees is actually increasing through time, potentially offsetting some of the carbon dioxide emissions that are released to the atmosphere," said Tello, an associate scientist at the Center for Conservation and Sustainable Development at the Missouri Botanical Garden.Tello leads the Madidi Project, a long-term study that the Missouri Botanical Garden has supported for nearly 20 years, involving plant diversity and forest change in Bolivia. Twenty-six of the forest plots included in this study were from the Madidi Project."Two critical research questions are how and why the functioning of ecosystems is being impacted by climate change," added Jonathan Myers, associate professor of biology in Arts & Sciences at Washington University, another co-author of the new study. "Carbon storage is one of the most important ecosystem services that helps to mitigate the effects of rising carbon dioxide levels under climate change and temperature warming."This study provides insights into how species on the move, under climate change, might be impacting these broader ecosystem services important to humanity," Myers said.Carbon is an important building block of life on Earth, but the element contributes to global warming when it is released into the atmosphere as carbon dioxide. Living plant tissues such as the stems, bark, branches and twigs of trees can act as a carbon sink because they absorb carbon dioxide from the atmosphere during photosynthesis.By locking in carbon, trees in forests around the world play a role in maintaining global climate stability. Some forests play a bigger role than others -- the Andes prime among them, the study found.Tropical and subtropical ecosystems are believed to account for nearly 70% of all the carbon sequestered by Earth's forests. But previous estimates of tropical carbon uptake were largely based on studies of lowland ecosystems, such as the Amazon.This study incorporates data from forest plots spanning a range of more than 3,000 meters (10,000 feet) in elevation across the subtropical and tropical Andes. The results indicate that the Andes are similar to other tropical forests in that they are acting as aboveground carbon sinks. However, the overall relative strength of the Andean carbon sink exceeds estimates from previous studies conducted in lowland tropical forests in Amazonia, Africa or Southeast Asia, the researchers discovered.Factors such as precipitation, temperature and size-dependent mortality of trees tend to drive carbon storage dynamics in Andean forests.Because of its vast size, the Amazon forest currently accumulates more carbon than the Andean forest. But recent research has suggested that the Amazon might become saturated with carbon in the near future. Under this scenario, the continued net uptake of carbon in Andean forests will become even more important.As a neighbor to the relatively well-studied Amazon forest, much about Andean forest ecosystems remains comparatively unknown. Challenging mountain terrain combined with remoteness makes it harder for scientists to reach parts of the Andes. It's also hard to secure funding to support large-scale research projects that span multiple countries."This paper collects and integrates information from lots of different research groups that have been working for decades independently," Tello said. "It's one of the first big efforts to bring together the scientists who have been monitoring these forests."William Farfan-Rios, a native of Cusco, Peru, and a postdoctoral research fellow of the Living Earth Collaborative, knows first-hand how difficult it is to conduct field research in the Andes. Since 2003, he has coordinated and led field campaigns and research projects with the Andes Biodiversity and Ecosystem Research Group, working along an elevational transect between the Andean and Amazonian forests in Peru. Farfan-Rios is also a co-author on the new study.Farfan-Rios recalled the challenges associated with one particular forest survey effort, saying: "At the beginning, we were a team of 14 people from Cusco. And, at the end, I was the only one who was still surveying those plots. I was the only survivor of this initial team! Right now, I'm still collaborating with that group and using this information for my postdoc with the Living Earth Collaborative."In only 1% of the Earth's land surface, the tropical Andes contain 15% of the world's plant species, or about 45,000 species in total. Approximately half of these plants -- about 20,000 species -- are endemic, meaning they are only found in the Andes. In addition to harboring extreme levels of biodiversity, Andean forests provide and protect sources of food, water and power for more than 50 million people. However, global environmental change -- including deforestation, human population growth and climate change -- is endangering Andean biodiversity and ecosystem services."Building on William's research and the finding that Andean forests are important carbon sinks and targets for conservation, it's important to understand how upward species migrations that are occurring under climate change might sustain those ecosystem services or functions in the future," Myers said. "Conservation initiatives not only support current forest biodiversity, but also habitats for species that will migrate to new areas in the future."
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Climate
| 2,021 |
April 19, 2021
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https://www.sciencedaily.com/releases/2021/04/210419110132.htm
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Northern Red Sea corals live close to the threshold of resistance to cold temperatures
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Coral reefs are one of the most biologically diverse ecosystems on earth. In the northern Red Sea and Gulf of Aqaba corals also have exceptionally high tolerance to increasing seawater temperatures, now occurring as a consequence of global warming. This characteristic led coral reef scientists to designate this region as a potential coral reef refuge in the face of climate change -- a reef where corals may survive longer than others that are being lost at an alarming rate due to human pressures.
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However, global climate change will also result in more variable weather patterns, including extreme cold periods. Some researchers predict that the Red Sea region is entering a cooling phase. Therefore, researchers from Bar-Ilan University and Interuniversity Institute for Marine Science in Eilat conducted an experiment to investigate the effect of an unusually cold winter on corals from the Gulf of Aqaba.In a paper recently published in the journal Previous studies conducted within the research group of Prof. Maoz Fine, of Bar-Ilan University's Mina and Everard Goodman Faculty of Life Sciences, have used controlled experiments in the Red Sea Simulator System to expose locally abundant corals to increased seawater temperatures expected to occur within and beyond this century. Multiple experiments found that corals from this region have an extraordinary tolerance to high temperatures, which kill corals elsewhere in the world. Prof. Fine's lab and researchers from other groups have tested multiple coral species and at different phases of their life cycle including the reproductive and larval phases, which are typically more sensitive to environmental change; all show similar tolerance."Whilst we have repeatedly demonstrated the high temperature tolerance of corals on the shallow reefs in Eilat, we wanted to test the possibility that this exceptional heat tolerance comes with the trade-off of being cold-sensitive," said Dr. Jessica Bellworthy, who conducted her doctoral research in Prof. Fine's lab. "Indeed we found that exposure to cold water periods causes a physiological response akin to bleaching." Better known as a response to high water temperatures, coral bleaching, is the loss of algal symbionts that must be present within the coral tissue in order to provide the coral with energy. Without the symbionts, the chances of coral mortality are high. Coral bleaching is the leading cause of coral decline in the world today. Therefore, while the corals of the Gulf of Aqaba can tolerate very high temperatures, even an acute cold spell may cause bleaching in this population.However, Bellworthy and Fine's cold stressed corals did not die and recovered once water temperatures returned to normal. Experimental corals were maintained at normal temperatures and then underwent a second test -- an anomalously hot summer. "It was an important discovery for us to understand that even those individuals that suffered the cold winter stress, still did not bleach at the high temperatures," says Bellworthy. This is good news for the corals in the Gulf of Aqaba; the high thermal tolerance is not lost and thereby corals should not undergo two bleaching events in the same year, a threat that faces others such as the Great Barrier Reef in Australia.Coral reefs are highly sensitive to temperature change. Therefore, identifying those that respond differently to thermal stress aids in understanding the mechanisms of environmental adaptation in corals. In addition, researchers can focus attention on conserving and studying such unique reefs.
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Climate
| 2,021 |
April 19, 2021
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https://www.sciencedaily.com/releases/2021/04/210419084256.htm
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Common plants and pollinators act as anchors for ecosystems
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The next time you go for a hike, take an extra moment to appreciate the seemingly ordinary life all around you. A house fly, humble yarrow weed and other "generalist" plants and pollinators play a crucial role in maintaining biodiversity and may also serve as buffers against some impacts of climate change, finds new University of Colorado Boulder research.
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The findings, published this month in "A lot of times, conservation efforts are geared toward things that are rare. But oftentimes, species that are common are also in decline and could go extinct, and that could have really big repercussions for maintaining biodiversity," said Julian Resasco, lead author on the study and assistant professor of ecology.A "generalist" simply refers to a species that interacts with a lot of other species. For example: A bee that visits many different species of flowers, or conversely, a flower that's visited by many species of bees and other pollinators, said Resasco.Bumblebees are well-known generalists, their fuzzy, cute bumbling bodies having garnered a large fan base of admirers over the years. But there are unsung heroes among generalist pollinators, including an insect that we often consider with disdain: flies. According to Resasco, some flies are the most common visitors to flowers, and they visit lots of different flowers.Generalist plants that Colorado residents may recognize include mountain parsley (Pseudocymopterus montanus), which are made up of bunches of small yellow flowers, and common yarrow (Ecologists have long studied networks of interactions between plants and pollinators, and previous research has shown that generalists can be found time and time again within and across landscapes, and during warm seasons or over several years. What this new study finds is that within seasons, over the span of many years and across the landscape, generalists are able to persist and act as anchors for their communities.Because so many species rely on generalists, having healthy populations of them helps support a robust community of plants and pollinators that are less susceptible to local extinctions, said Resasco. This robustness may also be important for buffering against increasing unequal shifts in the seasonal timing of species interaction due to climate change, known as phenological mismatch.For the past six years, Resasco has returned to the same mountain meadow in the morning each week, between snowmelt in May and the return of snowfall in September, to observe bumblebees, flies and beetles dance and hop between daisies, roses and asters at six different marked plots.There's nothing particularly unique about this east-facing meadow, surrounded by aspen and spruce-fir forest. But here, just below Niwot Ridge at 9,500 feet above sea level, near the CU Boulder Mountain Research Station, Resasco counted 267 different species of pollinators that visited the flowers of 41 species of plants -- and an encouragingly healthy number of generalists.Even Resasco, an experienced ecologist recently selected as an early career fellow by the Ecological Society of America (ESA), was surprised by the biodiversity that this meadow supports. Returning year after year to the same place, he found himself noticing more and more about the place."Every year teaches you something different," he said.And these findings teach us that what is common could be crucial to help ecosystems weather current and future environmental change. From setting conservation priorities that protect generalists to leaving your local flies and flowers in peace, there are many ways to support these critical but common species.Between late June and late July, these plants and pollinators will bloom and bustle in our backyards and nearby mountain meadows, awaiting hikers eager to see them. But if there aren't Instagram-worthy columbines waiting for you when you go, don't despair."If you just take some time to stop and observe what's around you, it's always interesting," said Resasco. "Don't overlook the common generalists."
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Climate
| 2,021 |
April 19, 2021
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https://www.sciencedaily.com/releases/2021/04/210419094035.htm
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Humans are directly influencing wind and weather over North Atlantic
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A new study led by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science provides evidence that humans are influencing wind and weather patterns across the eastern United States and western Europe by releasing CO
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In the new paper, published in the journal "Scientists have long understood that human actions are warming the planet," said the study's lead author Jeremy Klavans, a UM Rosenstiel School alumnus. "However, this human-induced signal on weather patterns is much harder to identify.""In this study, we show that humans are influencing patterns of weather and climate over the Atlantic and that we may be able to use this information predict changes in weather and climate up to a decade in advance," said Klavans.The North Atlantic Oscillation, the result of fluctuations in air pressure across the Atlantic, affects weather by influencing the intensity and location of the jet stream. This oscillation has a strong effect on winter weather in Europe, Greenland, the northeastern U.S. and North Africa and the quality of crop yields and productivity of fisheries in the North Atlantic.The researchers used multiple large climate model ensembles, compiled by researchers at the National Center for Atmospheric Research, to predict the North Atlantic Oscillation. The analysis consisted of 269 model runs, which is over 14,000 simulated model years.The study, titled "NAO Predictability from External Forcing in the Late Twentieth Century," was published on March 25 in the journal The study was supported by the National Science Foundation (NSF) Climate and Large-Scale Dynamics program (grant # AGS 1735245 and AGS 1650209), NSF Paleo Perspectives on Climate Change program (grant # AGS 1703076) and NOAA's Climate Variability and Predictability Program.
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Climate
| 2,021 |
April 16, 2021
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https://www.sciencedaily.com/releases/2021/04/210416194919.htm
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Unconventional takes on pandemics and nuclear defense could protect humanity from catastrophic failure
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From engineered pandemics to city-toppling cyber attacks to nuclear annihilation, life on Earth could radically change, and soon.
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"Our Earth is 45 million centuries old. But this century is the first when one species -- ours -- can determine the biosphere's fate," said Martin Rees, the United Kingdom's Astronomer Royal and a founder of the Centre for the Study of Existential Risks at Cambridge University.*"Our globally-linked society is vulnerable to the unintended consequences of powerful new technologies -- not only nuclear, but (even more) biotech, cyber, advanced AI, space technology," he added.Rees thinks biohackers pose a particularly underappreciated threat to humanity. In the near future, simple equipment will enable people to reengineer the human genome irrevocably or build a superspreading influenza. Like drug laws, regulations could never prevent all such actions -- and in a world more interconnected than ever before, the consequences would spread globally.He will discuss other dangers: population rise leading to plummeting biodiversity, disastrous climate change, uncontrollable cybercriminals, plans for artificial intelligence that erodes privacy, security, and freedom.But Rees is an optimist. He will offer a path toward avoiding these risks and achieving a sustainable future better than the world we live in today."If all of us passengers on 'spaceship Earth' want to ensure that we leave it in better shape for future generations we need to promote wise deployment of new technologies, while minimizing the risk of pandemics, cyberthreats, and other global catastrophes," he said.A single nuclear weapon could kill millions and destroy a city instantaneously. Hundreds of weapons could wipe out functioning society in a large nation. Even a limited nuclear war could cause a climate catastrophe, leading to the starvation of hundreds of millions of people.Recently, Russia, China, and North Korea have deployed new types of nearly unstoppable missiles."Missile defense is an idea that can sound appealing at first -- doesn't defense sound like the right thing to do?" said Frederick Lamb, astrophysicist at the University of Illinois at Urbana-Champaign, cochair of the 2003 APS Study of Boost-Phase Missile Defense, and chair of the current APS Panel on Public Affairs Study of Missile Defense and National Security."But when the technical challenges and arms race implications are considered, one can see that deploying a system that is intended to defend against intercontinental ballistic missiles is unlikely to improve the security of the United States," he said.Lamb points to the United Kingdom's decision to increase its nuclear arsenal by 44%, possibly motivated by Russia's new missile defense system around Moscow. He sees the move as yet another sign that existing limits on nuclear weapons are unraveling. Even missile defenses that would never work in practice can catalyze the development of new nuclear weapons and increase global risk.Lamb will share what may happen if the United States ramps up new missile defense systems."What is done about nuclear weapons and missile defenses by the United States and other countries affects the safety and survival of every person on the planet," he said.*Scientists will forecast the fate of the planet at a press conference during the 2021 APS April Meeting.
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Climate
| 2,021 |
April 16, 2021
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https://www.sciencedaily.com/releases/2021/04/210416120011.htm
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Alpine plants are losing their white 'protective coat' too early in spring
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Snow cover in the Alps has been melting almost three days earlier per decade since the 1960s. This trend is temperature-related and cannot be compensated by heavier snowfall. By the end of the century, snow cover at 2,500 meters could disappear a month earlier than today, as simulations by environmental scientists at the University of Basel demonstrate.
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Global warming demands huge adjustments in tourism, hydropower generation and agriculture in alpine areas. But the fauna and flora also have to adapt to rising temperatures. By the end of the century, continuous snow cover for 30 days below 1,600 meters is expected to be a rare occurrence. "Snow cover protects alpine plants from frost and the growing season begins after the snowmelt. Changes in the snowmelt have a very strong influence on this period," explains Dr. Maria Vorkauf of the Department of Environmental Sciences at the University of Basel. She researched alpine plant physiology intensively for her doctoral dissertation.In a new study, Vorkauf and colleagues at the University of Basel and the Institute for Snow and Avalanche Research investigated how the date of snowmelt has changed in recent decades and what shifts can be expected by the end of the 21st century. For a long time, only a few measurement series of snow cover at high elevations were available, as measurements were usually only made near inhabited regions below 2,000 meters. This changed with the IMIS measurement network, which went into operation in 2000. It automatically records the snow depth between 2,000 and 3,000 meters every half hour. The researchers combined this data with measurement series from 23 lower-lying stations with manual measurements going back to at least 1958.Analysis of the data showed that between 1958 and 2019, snow cover between 1,000 and 2,500 meters melted an average of 2.8 days earlier every decade. This shift was not linear, but was particularly strong in the late 1980s and early 1990s. This corresponds to strong temperature increases in this time period that have been verified by climate research.Based on the analyzed measurements, the researchers developed a model that makes it possible to forecast the future development of alpine snow cover. They combined their data with the latest climate scenarios for Switzerland. If greenhouse gas emissions continue to rise as they have so far, without consistent climate protection measures, the date of snowmelt in the last third of the 21st century is likely to move forward by six days per decade. This means that by the end of the century, snowmelt at 2,500 meters elevation would occur about one month earlier than today.The research also showed that the earlier snowmelt at high elevations cannot be compensated for by greater precipitation in the winter, as is predicted by climate models for Switzerland. "As soon as the three-week running mean of daily air temperatures exceeds 5 °C, snow melts relatively quickly," explains Vorkauf. "At high elevations in particular, temperature is much more important than the depth of the snow cover."In the future, the early snowmelt could extend the growing season of alpine plants by about a third. As is known from studies of other alpine plant species, an earlier start to the growing season leads to fewer flowers, less leaf growth and a lower survival rate due to the higher risk of frost. "Some species such as the Alpine sedge, which is typical of alpine grasslands, will grow and flower earlier because of the early snowmelt," says Vorkauf.Although temperatures in alpine areas are rising faster, alpine plant species are not more strongly affected by climate change than those at other elevations. "The topography and exposure of alpine terrain creates very diverse microclimates on a small scale. Within these, plants can retreat over short distances at the same elevation," Vorkauf explains. As a result, alpine plant species do not have to "flee" to the heights, as is often assumed.
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Climate
| 2,021 |
April 16, 2021
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https://www.sciencedaily.com/releases/2021/04/210416120005.htm
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Long-term consequences of CO2 emissions
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The life of almost all animals in the ocean depends on the availability of oxygen, which is dissolved as a gas in seawater. However, the ocean has been continuously losing oxygen for several decades. In the last 50 years, the loss of oxygen accumulates globally to about 2% of the total inventory (regionally sometimes significantly more). The main reason for this is global warming, which leads to a decrease in the solubility of gases and thus also of oxygen, as well as to a slowdown in the ocean circulation and vertical mixing. A new study published today in the scientific journal
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"In the study, a model of the Earth system was used to assess what would happen in the ocean in the long term if all COThe long-term decrease in oxygen takes place primarily in deeper layers. According to Prof. Oschlies, this also has an impact on marine ecosystems. A so-called 'metabolic index', which measures the maximum possible activity of oxygen-breathing organisms, shows a widespread decline by up to 25%, especially in the deep sea (below 2000 metres). This is likely to lead to major shifts in this habitat, which was previously considered to be very stable, explains the oceanographer. These changes have already been initiated by our historical COIn the upper layers of the ocean, the model shows a much faster response to climate action. There, a further expansion of the relatively near-surface oxygen minimum zones can be stopped within a few years if the emissions were stopped. An ambitious climate policy can therefore help to prevent at least the near-surface ecosystems from being put under further pressure by a progressive decrease in oxygen.
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Climate
| 2,021 |
April 15, 2021
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https://www.sciencedaily.com/releases/2021/04/210415170534.htm
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Modelling ancient Antarctic ice sheets helps us see future of global warming
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Last month saw the average concentration of atmospheric carbon dioxide (CO2) climb to almost 418 parts-per-million, a level not seen on Earth for millions of years. In order to get a sense of what our future may hold, scientists have been looking to the deep past. Now, new research from the University of Massachusetts Amherst, which combines climate, ice sheet and vegetation model simulations with a suite of different climatic and geologic scenarios, opens the clearest window yet into the deep history of the Antarctic ice sheet and what our planetary future might hold.
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The Antarctic ice sheet has attracted the particular interest of the scientific community because it is "a lynchpin in the earth's climate system, affecting everything from oceanic circulation to climate," says Anna Ruth Halberstadt, a Ph.D candidate in geosciences and the paper's lead author, which appeared recently in the journal Yet, it has been difficult to accurately reconstruct the mid-Miocene Antarctic climate. Researchers can run models, but without geologic data to check the models against, it's difficult to choose which simulation is correct. Conversely, researchers can extrapolate from geologic data, but such data points offer only local snapshots, not a wider climatic context. "We need both models and geologic data to know anything at all," says Halberstadt. There's one final complicating factor: geology. Antarctica is bisected by the Transantarctic Mountains, and any clear picture of Antarctica's deep history must be able to account for the slow uplift of the continent's mountain range. "Without knowing the elevation," says Halberstadt, "it's difficult to interpret the geologic record."Halberstadt and her colleagues, including researchers in both New Zealand and the UK, devised a unique approach in which they coupled an ice sheet model with a climate model, while also simulating the types of vegetation that would grow under each climatic model scenario. The team used historical geologic datasets that included such known paleoclimatic data points as past temperature, vegetation, and glacial proximity, to benchmark their modeled climates. Next, the team used their benchmarked model runs to make inferences about which CO2 and tectonic model scenarios satisfied the known geologic constraints. Finally, Halberstadt and her colleagues extrapolated continent-wide glacial conditions.The research, which was supported by the NSF, reconstructed a thick but diminished ice sheet under the warmest mid-Miocene environmental conditions. In this model, although the margins of Antarctica's ice sheet had retreated significantly, greater precipitation led to a thickening of the ice sheet's interior regions. The team's modelling further suggests ice over the Wilkes Basin region of Antarctica advanced during glacial periods and retreated during interglacials. The Wilkes Basin is the region thought to be particularly sensitive to future warming and may contribute to future sea level rise."Antarctica's paleoclimate," says Halberstadt, "is fundamental to understanding the future."
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Climate
| 2,021 |
April 15, 2021
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https://www.sciencedaily.com/releases/2021/04/210415142638.htm
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Deciduous trees offset carbon loss from Alaskan boreal fires
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More severe and frequent fires in the Alaskan boreal forest are releasing vast stores of carbon and nitrogen from burned trees and soil into the atmosphere, a trend that could accelerate climate warming. But new research published this week in the journal
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The study began in the wake of the dramatic 2004 fire season in Alaska when an area seven times the long-term average burned. Historically, more than half of this forested terrain has been dominated by black spruce, but after fire, faster-growing aspen and birch are replacing some of these stands. The team, made up of researchers from Northern Arizona University, the University of Alaska Fairbanks, Auburn University, and University of Saskatchewan surveyed 75 black spruce stands that burned in 2004 and followed their recovery over the next 13 years. They also collected a range of data from trees and soils of different ages and burn severities to construct a chronosequence, a kind of scientific time-lapse that lets researchers fast-forward through a 100-year fire cycle to see how forests recover and change."In 2005, I thought that there was no way these forests could recover the carbon they lost in this fire," said Michelle Mack, a professor of biology at Northern Arizona University and the lead author of the study. "The literature is full of papers suggesting deeper, more severe fires burn more carbon than can be replaced before the next fire. But not only did we see these deciduous trees make up for those losses, they did so rapidly."The team found that the new aspen and birch trees where the black spruce burned accumulated carbon and nitrogen more quickly than the spruce, storing most of it in their wood and leaves as opposed to the soil organic layer. And at the end of a projected 100-year cycle, the deciduous stands had recovered as much nitrogen as was lost to fire, and more carbon than was lost, resulting in an increase in the net ecosystem carbon balance. Calculating this balance is critical as scientists work to understand the way these northern forests are changing, and the effects of those changes on the global carbon picture."I was surprised that deciduous trees could replenish lost carbon so effectively and efficiently," said Heather Alexander, an assistant professor of forest ecology at Auburn and one of the paper's co-authors. "Even though considerable carbon is combusted and emitted into the atmosphere when black spruce forests burn severely, the deciduous trees that often replace them have an amazing ability to recapture and store carbon in their aboveground leaves and wood.""In a region with only five common tree species, this study shows how changes in tree composition can dramatically alter patterns of carbon storage in boreal forests," said Jill Johnstone, a northern researcher at University of Alaska-Fairbanks and co-author of the study."Carbon is just one piece of the puzzle," said Mack, who said deciduous forests have other important feedbacks, or interconnected effects, on climate. "We know these forests help cool regional climate, and we know that they are less ignitable, so fires are less likely to spread. Taken together, these effects create a relatively strong set of stabilizing climate feedbacks in the boreal forest."But there is a lot that researchers don't know about the fate of deciduous boreal forests in a warmer world."As mature deciduous trees die, will they be replaced with trees with the same structure, composition, and carbon storage abilities?" Alexander asked. "And will they recover from fire with the same carbon storage capacities?""Shifts from slow-growing black spruce to fast-growing deciduous species could balance out the impacts of the intensifying fire regime in the boreal forest," said Isla Myers-Smith, a global change ecologist at University of Edinburgh who was not involved in the study. "But it remains to be seen how carbon gains balance losses in future with accelerated warming at high latitudes."Mack said continued climate warming may undo the carbon-sequestering gains these trees represent. "The carbon should reside longer on the landscape because deciduous forests are less flammable. But flammability isn't a constant. The climate will pass a threshold where things get so hot and dry, even deciduous forests will burn. So, one question we need to ask is, how strong will the mitigating effect of low flammability be, and how long will it last?"Permafrost carbon also complicates the picture. Though many of the sites in this study did not have permafrost near the soil surface, the permanently frozen ground is found across the boreal biome. As it thaws, permafrost releases stores of carbon and methane, potentially offsetting the storage gains by deciduous trees, Mack said. "We will eventually pass a temperature threshold where negative feedbacks aren't enough."
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Climate
| 2,021 |
April 15, 2021
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https://www.sciencedaily.com/releases/2021/04/210415141848.htm
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Plankton genomes used as global biosensors of ocean ecosystem stress
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By analyzing gains and losses in the genes of phytoplankton samples collected in all major ocean regions, researchers at the University of California, Irvine have created the most nuanced and high-resolution map yet to show where these photosynthetic organisms either thrive or are forced to adapt to limited quantities of key nutrients, nitrogen, phosphorus and iron.
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As part of the new Bio-GO-SHIP initiative, the UCI scientists made eight deployments on six different research vessels, spending 228 days at sea in the Atlantic, Pacific and Indian oceans. They generated nearly 1,000 ocean metagenomes from 930 locations around the globe, with an average distance between collection points at 26.5 kilometers (about 16.5 miles).In a study published today in "Phytoplankton are foundational to the marine food web, and they are responsible for as much as half of global carbon dioxide fixation on an ongoing basis, so the health and distribution of these organisms is very important," said senior co-author Adam Martiny, UCI professor of Earth system science. "The knowledge gained on these voyages will help climatologists make more sound predictions about the role of phytoplankton in regulating carbon stocks in the atmosphere and ocean."Since microbial phytoplankton live in large populations and have rapid life cycles, the researchers suggest that changes in community composition and genomic content can provide an early warning about environmental transformations and do so far faster than by merely analyzing ocean physics and chemistry."Nitrogen, phosphorus and iron limitation in many surface ocean regions is nearly impossible to detect through chemical analysis of water samples; the quantities of these elements are just too low," said lead author Lucas Ustick, a UCI graduate student in ecology & evolutionary biology. "But quantifying shifts in Prochlorococcus genes involved in the uptake of major nutrients, and combinations thereof, provides a strong indicator of the geography of nutrient stress."The authors pointed out that all Prochlorococcus genomes include a certain gene that allows phytoplankton to directly assimilate the inorganic phosphate freely available in seawater. But when this compound is in short supply, phytoplankton adapt by gaining a gene that enables the cells to take up dissolved organic phosphorus, which can be detected in their genome.The researchers also studied numerous other examples of genetic adaptations for differing levels of phosphorus, iron and nitrogen in the environment to see what sorts of trade-offs the phytoplankton are continuously making. What resulted is a global map of nutrient stress. The researchers also were able to identify regions where phytoplankton experience co-stress involving two or more elements, one of them almost always being nitrogen.The team's work revealed the North Atlantic Ocean, Mediterranean Sea and Red Sea to be regions of elevated phosphorus stress. Genotypes adapted to nitrogen stress are widespread in so-called oligotrophic regions where nutrients are low and oxygen is high, and research sampling results suggest widespread adaptation to iron stress.Analysis of phytoplankton genotypes confirmed known biogeographic patterns of nutrient stress estimated by different techniques, but it also revealed previously unknown regions of nutrient stress and co-stress. The researchers had a scant understanding of nutrient stress in the Indian Ocean prior to their metagenomic analysis, but their work helped to fill in many blanks. They now know the Arabian Sea upwelling region to be an area of some iron stress, and they detected phosphorus stress associated with to south-flowing ocean currents, among many other findings.Still, they say, there is always more to learn."Our work highlights gaps in our measurements of high-latitude environments, in most of the Pacific Ocean, and in deeper-water ecosystems," said co-first author Alyse Larkin, UCI postdoctoral scholar in Earth system science. "The progress we made on our recent expeditions inspires us to head out and cover the whole planet."This project was funded by the National Science Foundation, NASA and the National Institutes of Health. Additional UCI researchers included Melissa Brock, graduate student in ecology & evolutionary biology; Keith Moore, professor of Earth system science; Nathan Garcia, project scientist in Earth system science; Catherine Garcia, a graduated Ph.D. student from Earth system science; Jenna Lee, a graduated UCI undergraduate student and Nicola Wiseman, graduate student in Earth system science.
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Climate
| 2,021 |
April 15, 2021
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https://www.sciencedaily.com/releases/2021/04/210415133203.htm
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Environmental protection could benefit from 'micro' as well as 'macro' thinking
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Scientists at the University of Southampton have conducted a study that highlights the importance of studying a full range of organisms when measuring the impact of environmental change -- from tiny bacteria, to mighty whales.
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Researchers at the University's School of Ocean and Earth Science, working with colleagues at the universities of Bangor, Sydney and Johannesburg and the UK's National Oceanography Centre, undertook a survey of marine animals, protists (single cellular organisms) and bacteria along the coastline of South Africa.Lead researcher and postgraduate student at the University of Southampton, Luke Holman explains: "Typically, biodiversity and biogeography studies focus on one group of species at a time, often animals. Studying animals, protist and bacteria together -- organisms vastly different in size, separated by billions of years of evolution -- gave us the opportunity to take a broader view of the marine ecosystem. We discovered remarkably consistent biogeographic groupings for the three across the coastline -- consistent with previously studied patterns, driven by regional currents."Findings are published in the journal The team took seawater samples in numerous locations along the length of the South African coast, from the warmer seas of the east, to the cooler waters of the west and the intermediate temperatures in the south. The samples were filtered, had environmental DNA extracted and underwent sophisticated lab analysis to indicate the diverse range of organisms found in particular locations.Results showed a broad range of animals living in the sea along the whole length of coast, but with differences in the exact species in warm, cold and intermediate regions. This same pattern of difference was also shown in bacteria and protists -- demonstrating consistency in the biodiversity of life for each region.Furthermore, the scientists found that among the variables examined temperature had the greatest impact on determining the diversity of animals and bacteria, whereas protists were associated more with chlorophyll concentration in the water. The team also revealed that while all three groups were affected to some extent by human activity, such as shipping, fishing and building of marinas, this wasn't to the extent they'd expected.Commenting on the study, Luke said: "We hope our work encourages researchers to consider other groups of organisms, both in biogeographic assessments and marine protection and restoration projects. For example, a project aiming to restore a coral reef might also need to consider the bacterial communities, or the protection of a river system might also ensure the protists communities are monitored in addition to the fish."Moving forwards the team hope to learn more about the causes and consequences of global marine biodiversity change for all life, from microscopic bacteria and protists to macroscopic organisms like fish and marine mammals.
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Climate
| 2,021 |
April 15, 2021
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https://www.sciencedaily.com/releases/2021/04/210415133155.htm
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Water purification system engineered from wood, with help from a microwave oven
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Researchers in Sweden have developed a more eco-friendly way to remove heavy metals, dyes and other pollutants from water. The answer lies in filtering wastewater with a gel material taken from plant cellulose and spiked with small carbon dots produced in a microwave oven.
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Reporting in the journal Minna Hakkarainen, who leads the Division of Polymer Technology at KTH Royal Institute of Technology, says that the hydrogels remove contaminants such as heavy metal ions, dyes and other common pollutants."The total amount of water on Earth doesn't change with time, but demand does," she says. "These all-lignocellulose hydrogels offer a promising, sustainable solution to help ensure access to clean water."The hydrogel composites can be made from 100 percent lignocellulose, or plant matter -- the most abundant bioresource on Earth, she says.One ingredient is cellulose gum (carboxymethyl cellulose, or CMC), a thickener and emulsion derived commonly from wood pulp or cotton processing byproducts and used in various food products, including ice cream. Added to the hydrogel are graphene oxide-like carbon dots synthesized from biomass with the help of microwave heat. The hydrogel composites are then cured with UV light, a mild process that takes place in water at room temperature.Hydrogels consist of a network of polymer chains that not only absorb water, but also collect molecules and ions by means of electrostatic interactions -- a process known as adsorption. Hakkarainen says the new process also reinforces the stability of the hydrogel composites so that they can outlast ordinary hydrogels for repeated cycles of water purification.Graphene oxide has become a favored additive to this mix, because of its high adsorption capacity, but the environmental cost of graphene oxide production is high."Graphene oxide is a great adsorbent, but the production process is harsh," she says. "Our route is based on common bio-based raw materials and significantly milder processes with less impact on the environment."Graphene is derived from graphite, a crystalline form of carbon that most people would recognize as the "lead" in pencils. In oxidized form it can be used in hydrogels but the oxidation process requires harsh chemicals and conditions. Synthesizing graphene from biomass often requires temperatures of up to 1300C.By contrast, the researchers at KTH found a way to carbonize biomass at much lower temperatures. They reduced sodium lignosulfate, a byproduct from wood pulping, into carbon flakes by heating it in water in a microwave oven. The water is brought to 240C, and it is kept at that temperature for two hours.Ultimately after a process of oxidation they produced carbon dots of about 10 to 80 nanometers in diameter, which are then mixed with the methacrylated CMC and treated with UV-light to form the hydrogel."This is a simple, sustainable system," Hakkarainen says. "It works as well, if not better, than hydrogel systems currently in use."
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Climate
| 2,021 |
April 14, 2021
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https://www.sciencedaily.com/releases/2021/04/210414155007.htm
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To improve climate models, an international team turns to archaeological data
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Climate modeling is future facing, its general intent to hypothesize what our planet might look like at some later date. Because the Earth's vegetation influences climate, climate models frequently include vegetation reconstructions and are often validated by comparisons to the past. Yet such models tend to get oversimplified, glossing over or omitting how people affected the land and its cover.
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The absence of such data led to LandCover6k, a project now in its sixth year that includes more than 200 archaeologists, historians, geographers, paleoecologists, and climate modelers around the world.Led by archeologists Kathleen Morrison of the University of Pennsylvania, Marco Madella of the Universitat Pompeu Fabra, and Nicki Whitehouse of the University of Glasgow, with data expertise from Penn landscape archaeologist Emily Hammer and others, LandCover6k's goal is to aggregate archaeological and historical evidence of land-use systems from four slices of time -- 12,000 years ago, 6,000 years ago, 4,000 years ago, and around the year 1500 -- into a single database that anyone can comprehend and use.The project offers what the researchers hope will become a tool to improve predictions about the planet's future, plus fill in gaps about its past. "Understanding the human impact on the Earth is more than looking at past vegetation. It's also important to understand how humans used the land and in particular, the relationship between human land use and vegetation," Morrison says.Though current Earth system models suggest that human activity during the past 12,000 years influenced regional and global climate, Madella says, "the models do not capture the diversity and intensity of human activities that affected past land cover, nor do they capture carbon and water cycles."Archaeology provides important information around land use that "helps reveal how humans have affected past land cover at a global scale," adds Whitehouse, "including the crops and animals being farmed, how they were being farmed, and how much land was needed to feed growing populations."In a new To share such data meant first creating a common language that scientists across disciplines could understand. It's a task more fraught than it might sound, Morrison says. "Classification means putting hard edges on something. That's very challenging, as archaeologists are often much more comfortable with narrative."Partially because of a lack of shared terminology, archaeologists have not tried to aggregate and compare data on a global scale, something the project's paleoecologists and modelers had already been doing, she adds. "We spent years consulting with colleagues around the world, discussing all the different types of land use and developing a communication system -- the same language, the same terminology -- that could be used anywhere."Because such categories historically have had different meaning depending on place, context, and time period, some archaeologists initially balked at committing to single definitions for each. Hammer offers the concept of "farming" as an example. "The line between what is called 'farming' and what is considered small-scale food production by hunter-gatherers really varies across the world," she says. So, how could the field fairly judge when the actions of hunter-gatherers managing wild plant and animal resources became "farming"?Questions like these prompted the LandCover6k team to create a hierarchy within the classification system, with an upper-level category capturing an idea at its broadest and several distinct sub-categories funneling down from there. In the farming example, the research team created a sub-group -- low-level food production -- which could include the work of the hunter-gatherers. The hope was to offer enough nuance for the archeological community yet still make the data accessible to climate modelers.In addition to this flexible hierarchy and the uniform terminology, the final classification has three other principal features. It is scale- and source-independent, meaning it accounts for the myriad ways something can be studied. It "takes the perspective of land rather than people," as the researchers write in PLOS ONE, and it employs a consistent 8x8 kilometer grid scale. "That's quite large, from an archaeological perspective," Hammer says, "but we did that so that one person isn't drawing something very small and another person very large."To showcase how the classification works, the researchers offer the example of the Middle East 6,000 years ago. This region, the area represented by modern day Iraq, Syria, Jordan, Kuwait, Saudi Arabia, Qatar, Bahrain, the United Arab Emirates, Oman, and Yemen, was home to some of the earliest agriculture in the world. Using the new classification and database, project participants built a regional land-use map, despite data availability differing from one spot to the next."Mesopotamia has been studied since the mid-19th century so there's a lot of data and a lot of syntheses to rely on," Hammer explains. "Arabia has not been nearly as well-studied. There are only a couple of data points, particularly for this period, and because of climatic events, the data are even rarer than for other periods. We wanted to illustrate the approach you would take in a situation where you have a lot of data versus a place with just a little." The new map of Middle Eastern land is proof of concept for the project, showing the contrast between the settled farms of Mesopotamia and the more sparsely settled lands of Arabia.The researchers don't see information gaps, like those of Arabia, as problematic. Rather because the land-use database also records data coverage and quality, it can highlight areas needing more research. "Humans have transformed landscapes for thousands of years," Morrison says. "But we can't just say that. We have to demonstrate it."And that's just what LandCover6k aims to do, merging what archaeologists have gleaned about human land use from different times and places into a single, accessible database for climate modelers -- and each other. "This project is really about translating what we do," Hammer says, "not only about the standardization of the terminology so we can talk at a global scale, but also about weaving together the narratives of the past."
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Climate
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April 14, 2021
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https://www.sciencedaily.com/releases/2021/04/210414154943.htm
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Ocean temperature reconstructed over the last 700,000 years
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Bern's ice core researchers were already able to demonstrate in 2008 how the concentration of CO
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The study's key findings: Mean ocean temperatures have been very similar over the last seven ice ages, averaging about 3.3 °C colder than the pre-industrial reference period, as already suggested by syntheses of deep water temperatures from marine sediments. However, ocean temperatures in the warm periods 450,000 years ago were much colder and CO"To understand how the climate system's heat balance is changing," says Hubertus Fischer, "we have to understand the ocean first and foremost." For example, 93 percent of the additional heat that humans accumulate by increasing greenhouse gases is currently stored in the ocean rather than in the atmosphere. This means that without the ocean's heat uptake, the temperature increase measured on land due to human-induced climate change would be significantly greater. However, because the oceans have a huge mass compared to the atmosphere, the temperature changes measured in the ocean today are very small.The relevance of data from the ocean for climate research is demonstrated by the international ARGO project, a mobile observation system for the world's oceans with which for example continuous temperature measurements down to a depth of 2,000 meters have been carried out since 2000. Roughly 4,000 drifting buoys distributed over all oceans are used for this. This makes the approach of Bern's researchers all the more astonishing in comparison: "We only need a single polar ice sample for our mean ocean temperature measurement," explains Hubertus Fischer, "of course we are nowhere near the accuracy of ARGO, but conversely we can look far back into the past." What is being studied is not frozen seawater, but air bubbles trapped in Antarctica's glacier ice. Specifically: the noble gases argon, krypton, xenon and molecular nitrogen. The majority of these gases are in the atmosphere, just a small fraction is dissolved in the ocean. How well each gas is dissolved in seawater depends on the ocean temperature. Therefore, the changing ratio of these gases in the ice samples can be used to reconstruct past mean ocean temperatures."The prerequisite for this method are high-precision measurements using a dynamic mass spectrometer," emphasizes Hubertus Fischer, "which were made possible by the great efforts of several doctoral students and postdocs involved in the publication." Processing and measurement methods developed in Bern as part of the MATRICs project funded by the European Research Council (ERC) are also crucial. Past ocean temperatures are determined to within 0.4 °C in Bern. This precision makes it possible to trace the climatic ups and downs of the past, since the difference in mean ocean temperature between the ice age and the warm phases over the past 700,000 years was about 3 °C. In addition to the laboratory in Bern, only the Scripps Institute of Oceanography in San Diego, USA, which Bern's researchers work closely with, has so far carried out such measurements worldwide.
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Climate
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April 14, 2021
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https://www.sciencedaily.com/releases/2021/04/210414113543.htm
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Climate change is making it harder to get a good cup of coffee
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Ethiopia may produce less specialty coffee and more rather bland tasting varieties in the future. This is the result of a new study by an international team of researchers that looked at the peculiar effects climate change has on Africa's largest coffee producing nation. Their results are relevant both for the country's millions of smallholder farmers, who earn more on specialty coffee than on ordinary coffee, as well as for baristas and coffee aficionados around the world.
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"Climate change has conflicting impacts on coffee production in Ethiopia. The area that is suitable for average quality coffee might actually increase gradually until the 2090s, according to our computer simulations," says lead author Abel Chemura from the Potsdam Institute for Climate Impact Research (PIK). "Yet more is not necessarily better. Because on the flipside, the suitable area for high quality specialty coffee types which are valued for their floral, fruity and spicy notes, will likely shrink if climate change continues unchecked. This is an issue not just for coffee lovers, but for local agricultural value creation."Under various scenarios the researchers looked at how a total of 19 climatic factors will affect the cultivation of five distinct specialty coffee types in the future, including mean temperature, annual rainfall levels, and seasonality. For example, if it gets warmer, the coffee cherry matures faster than the development of the bean, which in turn leads to coffee that is lower in quality. Increased rainfall, on the other hand, favors coffee production in general but may be not necessarily beneficial for individual specialty coffee types.Thus, while the researchers project that the area suitable for four out of five specialty coffee types will decline, some are hit harder than others. For example, the renowned Yirgacheffe type, one of the world's oldest and most sought after coffee types cultivated in Ethiopia's southwest, under the worst case scenario, could lose more than 40% of its suitable area by the end of the 21st century.This would not only affect coffee drinkers worldwide, especially those who grind their own beans or prefer sophisticated blends -- it would also have consequences for Ethiopia's economy. "If one or more coffee regions lose their specialty status due to climate change this has potentially grave ramifications for the smallholder farmers in the region," says co-author Christoph Gornott from PIK and the University of Kassel, Germany. "If they were forced to switch to growing conventional, less palatable and bitter coffee types, they would all of the sudden compete with industrial production systems elsewhere that are more efficient. For the country, in which coffee exports account for roughly a third of all agricultural exports, this could prove fatal."However, there may be ways to stop this trend. "As distinct specialty coffee types are strongly influenced by different local climatic, spatial and soil-related factors, what is needed are adaptation measures that are tailored to each specific region," adds Christoph Gornott. "Our study underscores the importance of localized adaptation planning and responses. We show how climate change has very concrete effects on the availability and taste of one of the world's most beloved beverages and, more importantly, on economic opportunities in local communities of the global South."
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Climate
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April 14, 2021
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https://www.sciencedaily.com/releases/2021/04/210414100141.htm
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Climate change is making Indian monsoon seasons more chaotic
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If global warming continues unchecked, summer monsoon rainfall in India will become stronger and more erratic. This is the central finding of an analysis by a team of German researchers that compared more than 30 state-of-the-art climate models from all around the world. The study predicts more extremely wet years in the future -- with potentially grave consequences for more than one billion people's well-being, economy, food systems and agriculture.
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"We have found robust evidence for an exponential dependence: For every degree Celsius of warming, monsoon rainfalls will likely increase by about 5%," says lead author Anja Katzenberger from the Potsdam-Institute for Climate Impact Research (PIK) and Ludwig-Maximilian University in Munich, Germany (LMU). "Hereby we were also able to confirm previous studies but find that global warming is increasing monsoon rainfall in India even more than previously thought. It is dominating monsoon dynamics in the 21st century."More rainfall is not necessarily a good thing for the farming sector in India and its neighboring countries. As co-author Julia Pongratz from LMU explains: "Crops need water especially in the initial growing period, but too much rainfall during other growing states can harm plants -- including rice on which the majority of India's population is depending for sustenance. This makes the Indian economy and food system highly sensitive to volatile monsoon patterns."A look into the past underlines that human behavior is behind the intensification of rainfall. Starting in the 1950s, human-made forcings have begun to overtake slow natural changes occurring over many millennia. At first, high sun-light blocking aerosol loadings led to subdued warming and thus a decline in rainfall, but since then, from 1980 onwards, greenhouse gas-induced warming has become the deciding driver for stronger and more erratic Monsoon seasons."We see more and more that climate change is about unpredictable weather extremes and their serious consequences," comments group leader and co-author Anders Levermann from PIK and Columbia University, New York/USA on the findings of the study published in the journal
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Climate
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April 14, 2021
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https://www.sciencedaily.com/releases/2021/04/210414100139.htm
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Indigenous land-use reduced catastrophic wildfires on the Fish Lake Plateau
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If you were to visit the Great Basin and Colorado Plateau a thousand years ago, you'd find conditions remarkably familiar to the present. The climate was warm, but drier than today. There were large populations of Indigenous people known as the Fremont, a who hunted and grew crops in the area. With similar climate and moderate human activity, you might expect to see the types of wildfires that are now common to the American West: infrequent, gigantic and devastating. But you'd be wrong.
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In a new study led by the University of Utah, researchers found that the Fremont used small, frequent fires, a practice known as cultural burning, which reduced the risk for large-scale wildfire activity in mountain environments on the Fish Lake Plateau -- even during periods of drought more extreme and prolonged than today.The researchers compared lake sediment, tree ring data and archaeological evidence to reconstruct a 1,200 history of fire, climate, and human activity of the Fish Lake Plateau, a high-elevation forest in central Utah in the United States. They found that frequent fires occurred between the years 900 and 1400, a period of intense farming activity in the region. Prehistoric cooking hearths and pollen preserved in lake sediment show that edible plant species dominated the landscape during this period, indicating that Fremont people practiced cultural burning to support edible wild plants, including sunflowers, and other crops. Large-scale farming ceased after the year 1400. Hunters and foragers, ancestors of the Ute and Paiute, continued to burn, although less frequently than during the farming period. After Europeans made cultural burning illegal, the ecosystem returned to be dominated by a thick forest of trees."When you have people burning frequently, they're reducing the amount of surface fuels present on the landscape. It makes it much more difficult for a lightning fire to reach up to the canopy and burn down the entire forest," said Vachel Carter, postdoctoral research assistant at the U and lead author of the study. "Now we have an environment dominated by trees in a very dry environment, which are conditions prime for megafires. Is this a result of climate change? Definitely. But in the case at Fish Lake, it could also be attributed to a lack of cultural burning."For millennia through the present, Indigenous people across North America have used cultural burning to drive game, ease travel, clear vegetation for fields and enhance regrowth of edible plants. European settlers banned the practice in favor of fire suppression, the strategy that's dominated forest management since the turn of the 20th century."All over North America, humans have always modified fire regimes to benefit themselves and their families," said Brian Codding, associate professor of anthropology at the U and senior author of the paper. "Cultural burning is something that needs to be considered when people are talking about how to manage forests, just like in the Fish Lake National Forest."The paper published April 14, 2021 in the Nature journal The study is the first in the region to combine charcoal, pollen, tree ring and archeological site data together to assess human influence on prehistoric wildfires. The multiple disciplines allowed the researchers to make connections that would otherwise have been impossible."This is really showing us something that's kind of invisible otherwise," said Codding. "People have been trying to look at human impacts on fire regimes all over the place, and it's really hard. Because the changes might be really subtle, or our records just aren't fine-grained enough to record the types of changes that can reveal it."Colleagues from Utah State University and Brigham Young University contributed tree ring data that document how the climate has shifted over time. Thick rings mean that the tree grew rapidly, indicating there was more moisture available. Narrow rings represent a slow growth year due to less moisture, a signature that can record periods of drought. For this study, they established a climatological timeline for the Fish Lake area.Carter analyzed the contents of ancient sediments to reconstruct past worlds. Detritus from the local environment blows over the lake and settles at the bottom, building up layers as time passes. Each layer provides a snapshot of what the surrounding area was like at a particular time. She used charcoal as a proxy for fire abundance -- more charcoal means more frequent fire -- and analyzed pollen grains to determine what plant species dominated and compared how those changed over the last 1,200 years.Codding and colleagues counted the number of sites that were occupied, using radiocarbon dates on items found at dwelling sites to establish when people were there. They also used food remnants in cooking hearths to establish the types of food people were eating. They analyzed sites within modern day Sevier County, the area around and including Fish Lake, the ancestral lands of the Ute and Paiute Tribes."From the cooking hearths found at Fish Lake, we got an indication of what people were eating, and when they were eating it. We knew that they were eating food in the sunflower family, the grass family, and the sedge family, all these plants that don't naturally dominate a high elevation forest," said Carter. "I counted the pollen from those species in the sediment cores and, sure enough, when the Fremont were present, those same plant species were present in much higher abundances than when the Fremont were absent.""This piece really pulls the study together for linking how people living at this area, at higher densities, were actually modifying the environment to increase the resources that were available to them," Codding said.In Utah, many forests could benefit from frequent, smaller fires to mitigate wildfire risk. Perhaps one of the most urgent is in the Fish Lake National Forest that guards Pando, a stand of 47,000 aspen tree clones and the most massive organism on Earth. Pando has sat at the south end of Fish Lake for thousands of years, at least -- some say the organism is a million years old. In recent years, the beloved grove has been shrinking. Low severity fires may help Pando, and other Utah forests, stay healthy."Fuels on the Fish Lake landscape are at the highest that they've been in the last 1,200 years. The climate is much warmer than it was in the past. Our droughts have not been as intense as we've seen in the past, but they're on their way," Carter said. "The Fremont likely created long-lasting legacies on the Fish Lake Plateau through their cultural burning. Moving forward, 'good fire,' like prescribed fire, will be needed to mitigate against wildfire risk."
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Climate
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April 13, 2021
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https://www.sciencedaily.com/releases/2021/04/210413110628.htm
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Snow chaos in Europe caused by melting sea-ice in the Arctic
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They are diligently stoking thousands of bonfires on the ground close to their crops, but the French winemakers are fighting a losing battle. An above-average warm spell at the end of March has been followed by days of extreme frost, destroying the vines with losses amounting to 90 percent above average. The image of the struggle may well be the most depressingly beautiful illustration of the complexities and unpredictability of global climate warming. It is also an agricultural disaster from Bordeaux to Champagne.
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It is the loss of the Arctic sea-ice due to climate warming that has, somewhat paradoxically, been implicated with severe cold and snowy mid-latitude winters."Climate change doesn't always manifest in the most obvious ways. It's easy to extrapolate models to show that winters are getting warmer and to forecast a virtually snow-free future in Europe, but our most recent study shows that is too simplistic. We should beware of making broad sweeping statements about the impacts of climate change." Says professor Alun Hubbard from CAGE Center for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway.Hubbard is the co-author of a study in The study, led by Dr. Hanna Bailey at the University of Oulu, Finland, has more specifically found that the long-term decline of Arctic sea-ice since the late 1970s had a direct connection to one specific weather event: "Beast from the East" -- the February snowfall that brought large parts of the European continent to a halt in 2018, causing £1bn a day in losses.Researchers discovered that atmospheric vapour traveling south from the Arctic carried a unique geochemical fingerprint, revealing that its source was the warm, open-water surface of the Barents Sea, part of the Arctic Ocean between Norway, Russia, and Svalbard. They found that during the "Beast from the East," open-water conditions in the Barents Sea supplied up to 88% of the corresponding fresh snow that fell over Europe."What we're finding is that sea-ice is effectively a lid on the ocean. And with its long-term reduction across the Arctic, we're seeing increasing amounts of moisture enter the atmosphere during winter, which directly impacts our weather further south, causing extreme heavy snowfalls. It might seem counter-intuitive, but nature is complex and what happens in the Arctic doesn't stay in the Arctic." says Bailey.When analyzing the long-term trends from 1979 onwards, researchers found that for every square meter of winter sea-ice lost from the Barents Sea, there was a corresponding 70 kg increase in the evaporation, moisture, and snow falling over Europe.Their findings indicate that within the next 60 years, a predicted ice-free Barents Sea will likely become a significant source of increased winter precipitation -- be it rain or snow -- for Europe."This study illustrates that the abrupt changes being witnessed across the Arctic now, really are affecting the entire planet." says professor Hubbard.
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Climate
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April 12, 2021
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https://www.sciencedaily.com/releases/2021/04/210412194220.htm
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Ocean bacteria release carbon into the atmosphere
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A team led by University of Minnesota researchers has discovered that deep-sea bacteria dissolve carbon-containing rocks, releasing excess carbon into the ocean and atmosphere. The findings will allow scientists to better estimate the amount of carbon dioxide in Earth's atmosphere, a main driver of global warming.
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The study is published in "If COThe researchers began studying sulfur-oxidizing bacteria -- a group of microbes that use sulfur as an energy source -- in methane seeps on the ocean floor. Akin to deep-sea coral reefs, these "seeps" contain collections of limestone that trap large amounts of carbon. The sulfur-oxidizing microbes live on top of these rocks.After noticing patterns of corrosion and holes in the limestone, the researchers found that in the process of oxidizing sulfur, the bacteria create an acidic reaction that dissolves the rocks. This then releases the carbon that was trapped inside the limestone."You can think of this like getting cavities on your teeth," Leprich said. "Your tooth is a mineral. There are bacteria that live on your teeth, and your dentist will typically tell you that sugars are bad for your teeth. Microbes are taking those sugars and fermenting them, and that fermentation process is creating acid, and that will dissolve away at your teeth. It's a similar process to what's happening with these rocks."The researchers plan to test out this effect on different mineral types. In the future, these findings could also help scientists use dissolution features -- holes, crevices, or other evidence that rocks have been dissolved by bacteria -- to discover evidence of life on other planets, such as Mars."These findings are but one of the many examples of the important and understudied role that microbes play in mediating the cycling of elements on our planet," said Jake Bailey, a University of Minnesota Department of Earth and Environmental Sciences associate professor and corresponding author of the study.
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Climate
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April 12, 2021
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https://www.sciencedaily.com/releases/2021/04/210412161859.htm
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Road salts and other human sources are threatening world's freshwater supplies
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When winter storms threaten to make travel dangerous, people often turn to salt, spreading it liberally over highways, streets and sidewalks to melt snow and ice. Road salt is an important tool for safety, because many thousands of people die or are injured every year due to weather related accidents. But a new study led by Sujay Kaushal of the University of Maryland warns that introducing salt into the environment -- whether it's for de-icing roads, fertilizing farmland or other purposes -- releases toxic chemical cocktails that create a serious and growing global threat to our freshwater supply and human health.
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Previous studies by Kaushal and his team showed that added salts in the environment can interact with soils and infrastructure to release a cocktail of metals, dissolved solids and radioactive particles. Kaushal and his team named these cascading effects of introduced salts Freshwater Salinization Syndrome, and it can poison drinking water and cause negative effects on human health, agriculture, infrastructure, wildlife and the stability of ecosystems.Kaushal's new study is the first comprehensive analysis of the complicated and interconnected effects caused by Freshwater Salinization Syndrome and their impact on human health. This work suggests that the world's freshwater supplies could face serious threats at local, regional and global levels if a coordinated management and regulation approach is not applied to human sources of salt. The study, which calls on regulators to approach salts with the same level of concern as acid rain, loss of biodiversity and other high-profile environmental problems, was published April 12, 2021, in the journal "We used to think about adding salts as not much of a problem," said Kaushal, a professor in UMD's Department of Geology and Earth System Science Interdisciplinary Center. "We thought we put it on the roads in winter and it gets washed away, but we realized that it stuck around and accumulated. Now we're looking into both the acute exposure risks and the long-term health, environmental, and infrastructure risks of all these chemical cocktails that result from adding salts to the environment, and we're saying, 'This is becoming one of the most serious threats to our freshwater supply.' And it's happening in many places we look in the United States and around the world."When Kaushal and his team compared data and reviewed studies from freshwater monitoring stations throughout the world, they found a general increase in chloride concentrations on a global scale. Chloride is the common element in many different types of salts like sodium chloride (table salt) and calcium chloride (commonly used for road salt). Drilling down into data from targeted regions, they also uncovered a 30-year trend of increasing salinity in places like the Passaic River in northern New Jersey and a 100-mile-plus stretch of the Potomac River that supplies drinking water to Washington, D.C.The major human-related salt source in areas such the Northeastern U.S. is road salts, but other sources include sewage leaks and discharges, water softeners, agricultural fertilizers and fracking brines enriched with salts. In addition, indirect sources of salts in freshwater include weathering roads, bridges and buildings, which often contain limestone, concrete or gypsum, all of which release salt as they break down. Ammonium-based fertilizers can also lead to the release of salts in urban lawns and agricultural fields. In some coastal environments, sea-level rise can be another source of saltwater intrusion.The study points to a growing body of research from around the world that shows how chemical cocktails released by all of these salt sources harm both natural and built environments. For example, changes in salt levels can allow invasive, more salt-tolerant species to take over a stream. Chemical cocktails released by salts can change the microbes in soil and water, and because microbes are responsible for decay and replenishment of nutrients in an ecosystem, that shift can lead to even more changes in the release of salts, nutrients and heavy metals into the environment.In the built environment, salts can degrade roadways and infrastructure. They can also corrode water pipes causing the release of heavy metals into drinking water supplies as they did in Flint, Michigan."I am greatly surprised by the increasing scope and intensity of these problems as highlighted from our studies," said study co-author Gene E. Likens, founding president emeritus of the Cary Institute of Ecosystem Studies and a distinguished research professor at the University of Connecticut. "Increased salinization of surface waters is becoming a major environmental problem in many places in the world."The variety of sources and complex interactions between salt and the environment are poorly understood, and every lake, stream and aquifer presents a different set of management challenges. The study suggests that management strategies must evaluate salt contributions from different sources on a watershed-ecosystem level and prioritize regulation accordingly, much the way nutrient loads in watersheds are currently managed.Improvements in technology have helped reduce nutrient runoff, but safe and effective alternatives to road salts do not yet exist. Kaushal hopes that regulation, new technologies and a coordinated management approach can reduce the potential threats of Freshwater Salinization Syndrome on a broad scale."Ultimately, we need regulation at the higher levels, and we're still lacking adequate protection of local jurisdictions and water supplies," Kaushal said. "We have made dramatic improvements to acid rain and air quality, and we're trying to address climate change this way. What we need here is a much better understanding of the complicated effects of added salts and regulations based on that. This can allow us to avert a really difficult future for freshwater supplies."Going forward, the study emphasizes the importance of increasing water monitoring efforts and using modern sensor technology to capture continuous data. High-frequency sensor data allows scientists and managers to detect peaks in salinity and water flow that may eventually help them to predict the chemical composition and accumulation of toxins due to Freshwater Salinization Syndrome.In addition, Kaushal said field studies and experiments that trace the rapidly expanding effects of salt in the environment are needed to improve scientific understanding of the problem. He has been conducting such research in the streams running through and near UMD's College Park campus, an urban environment inside the Washington, D.C. Beltway.
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Climate
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April 12, 2021
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https://www.sciencedaily.com/releases/2021/04/210412114755.htm
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Greenhouse gas emissions from Chinese inland waters
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Inland waters are an important component of the global carbon cycle and function as active reactors, transporting and transforming large quantities of naturally- and anthropogenically-derived carbon. Previous studies suggest that inland waters are major sources for greenhouse gas emissions to the atmosphere, yet these emissions are poorly constrained (Note 1).
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As a primary greenhouse gas that drives global climate change, carbon dioxide (COResearchers at the Department of Geography of the University of Hong Kong (HKU), together with collaborators from Australia, Germany, Switzerland, China, and the USA, have for the first-time, quantified COIn combination with remote sensing techniques, the research team estimated COThe findings revealed an overall decrease of 29% of COStreams and rivers are the primary emitters, accounting for 88% to 93% of the total evasion. In 2010, total CO"Our findings suggest that this unexpected decrease was driven by a combination of environmental alterations, including massive conversion of free-flowing rivers to reservoirs and widespread implementation of reforestation programmes. Conversion of free-flowing rivers to reservoirs which show physicochemical properties analogous to lakes caused a significant reduction of COThe total surface area of rivers and streams during the period has decreased by 8.1 to 10.4%, while the total surface area of lakes and reservoirs has increased by 13.1% (Table 2). Overall, the total surface area of Chinese inland waters increased by about 8600 km2 on average (6%) in the 2010s when compared with the 1980s."China has engaged in a dam boom since the 1980s with a surging economy that spurred the need for energy and food production. With about 15,000 new reservoirs being completed between the two periods, the storage capacity of reservoirs more than doubled. Therefore, the reduction in stream surface area between the two periods has been offset by the simultaneous expansion of lakes and reservoirs." Dr Ran explained.The Tibetan Plateau is spatially the only region showing increased emission from streams/rivers, lakes and reservoirs, with riverine and lake CO"Since COFrom the findings, the efflux estimates could reduce the magnitude of the terrestrial carbon sink within China for the 1980s by 24% to 59%. As a result of implementation of nationwide ecological restoration programs since the early 1980s, terrestrial ecosystems across China have been greatly restored in the 2010s. Even so, accounting for the simultaneous CO"Considering that China's diverse climatic and geomorphologic systems mimic global landscapes and comprise most of the global vegetation types, we contend that excluding inland water CO"This study represents the first comprehensive approach to evaluating changes in aquatic CONote 1 Regnier P, et al. 2013. Anthropogenic perturbation of the carbon fluxes from land to ocean. Note 2 Butman, D., and P. A. Raymond. 2011. Significant efflux of carbon dioxide from streams and rivers in the United States, Note 3 Borges, A. V., F. Darchambeau, C. R. Teodoru, T. R. Marwick, F. Tamooh, N. Geeraert, F. O. Omengo, F. Guérin, T. Lambert, and C. Morana. 2015. Globally significant greenhouse-gas emissions from African inland waters, Lu F, et al. 2018. Effects of national ecological restoration projects on carbon sequestration in China from 2001 to 2010. Raymond PA, et al. 2013. Global carbon dioxide emissions from inland waters.
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April 12, 2021
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https://www.sciencedaily.com/releases/2021/04/210412101926.htm
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Thawing permafrost cools Arctic currents: This might affect fish stocks
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A new study by a University of Copenhagen researcher finds that thawing permafrost in Alaska causes colder water in smaller rivers and streams. This surprising consequence of climate change could affect the survival of fish species in the Arctic's offshore waters.
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The study's researchers discovered that thawing permafrost causes groundwater to run deeper, where it becomes cooler than when it flows near the soil surface.Rising global temperatures are causing frozen Arctic soil -- permafrost -- to thaw. In a new study, researchers have discovered something surprising: small rivers, creeks and streams that flow into larger lakes and coastal waters seem be to getting colder as permafrost melts. The phenomenon was previously documented in Russian rivers in the Arctic. But until now, no one had studied why the water was getting colder, even as air temperatures are warming and the permafrost is thawing.Together with researchers from the US Geological Survey Alaska Science Center, Associate Professor Ylva Sjöberg of UCPH's Department of Geosciences and Natural Resource Management has shed new light on this cold water. The study's researchers discovered that thawing permafrost causes groundwater to run deeper, where it becomes cooler than when it flows near the soil surface."Permafrost is found just beneath the ground's surface. When permafrost is intact, groundwater flows from springs and the mountains and atop the permafrost layer, where it is significantly heated throughout summer. However, as permafrost disappears, runoff seeps deeper into the ground, where it cools before making its way into nearby streams, rivers and lakes," explains Ylva Sjöberg, the study's lead author.In their study, the researchers studied the Noatak National Preserve in northwest Alaska. As with other Arctic areas, the Noatak is experiencing higher temperature due to climate change.However, very little data is available for how climate change affects the temperature of smaller water flows. The researchers positioned 62 measuring sensors in different streams in areas both with and without permafrost. Here, they observed that water temperatures were warmer in permafrost-covered areas.Using a computer model, the researchers were able to calculate that the summer water temperatures would average 11 degrees in areas of permafrost, while in areas without permafrost, it would be 4 degrees."We have no reason to believe that our observations in Alaska would be any different in other Arctic regions with analogous landscapes. This complicates the effects of climate change, as it seems that areas with permafrost are not subject to the same simple ratio of temperature increases in air and water as are used elsewhere," explains Ylva Sjöberg.Salmon, grayling and sculpin are a few of the fish species that spawn and grow in these streams. Fish biologists from the U.S. Geological Survey (USGS) Alaska Science Center made initial observations of how cooler water temperatures might affect fish."Stream temperature ultimately determines a fish's ability to reproduce and survive. We suspect that colder water may limit how large a fish grows and likely limits whether they will thrive," explains Michael P. Carey, USGS fish biologist.According to the biologists, who are now busy with analysing the study data, thawing permafrost can also introduce other factors that may disturb the aquatic environments of these fish."Streams draining from areas of thawing permafrost will likely show not only temperature fluctuations but also an increase in carbon and nutrient runoff," concludes Carey.
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Climate
| 2,021 |
April 12, 2021
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https://www.sciencedaily.com/releases/2021/04/210412084551.htm
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Thick sea-ice warms Greenland fjords
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A new study shows that thick sea-ice can increase the sensitivity of Greenlandic fjords to climate warming. Understanding the factors that control how fast glaciers move, break up and deposit chunks of ice (icebergs) into the fjords -- and eventually the sea -- is vital for predicting how the Greenland ice sheet will change under a warming climate and for predicting global rates of sea-level rise.
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A new study led by Stockholm University Assistant Professor Christian Stranne, shows that thick sea-ice outside the fjords can actually increase the sensitivity of Greenlandic fjords to warming. Stranne and a team of researchers from Sweden, Greenland, the Netherlands, the USA, and Canada report on expeditions to two distinct fjords in northern Greenland during the 2015 and 2019 summers. "These fjords were practically inaccessible to researchers until quite recently because the sea-ice was too thick -- they are some of the least-studied areas on the planet, and require a large icebreaker to reach them, even in the summer," says Stranne. The inaccessibility and sea-ice build-up is due to the direction of Arctic Ocean currents; the Beaufort Gyre and Transpolar Drift push ice from across the Arctic up against the northern Greenland coast.Writing in In 2019, air temperatures in northern Greenland reached record highs. Despite similar high air temperatures and conditions, Petermann Fjord's near surface sea temperatures never exceeded 0ºC. "But in the Sherard Osborn Fjord, cut off from the open ocean by thick sea-ice, near surface sea temperatures reached 4ºC -- which was 3ºC higher than any previous seawater measurement north of Greenland," explains Stranne.Summertime melt produces a warm freshwater layer floating atop saltier water in the fjord; here the sea-ice barrier trapped this meltwater inside the fjord. Because of the difference in salt content, the surface water became isolated also from the water below, allowing time for intense solar heating of the fresher surface water. Such warmer water temperatures can contribute to faster melting of the Ryder Glacier in Sherard Osborn Fjord, as well as changing the biogeochemistry in the fjord waters. Conversely, the researchers suggest, that neighboring Petermann Fjord, which was open to the sea during 2015 and 2019, experienced colder surface water temperatures because its surface water was not isolated within the fjord by a sea-ice barrier.These observations are counterintuitive: thick sea-ice is associated with colder climates, yet it can lead to warmer surface water temperatures inside the fjords. For this reason, fjords along the northern Greenland coast are more sensitive to climate warming than fjords without a sea-ice barrier.But each fjord is a little different. Last year, another study from the 2015 and 2019 expeditions pointed out that Ryder Glacier in Sherard Osborn Fjord is less affected by melting of the ice tongue from underneath, compared to Petermann Glacier in Petermann Fjord. In this case the explanation is not sea-ice but the shape of the seafloor that produces a shallower opening to the sea. The physical block of rock and sediment dampens intrusions of deeper warm water from outside the fjord (of Atlantic origin) which tends to make Ryder Glacier less sensitive to climate warming -- while at the same time, surface sea-ice in the adjacent Lincoln Sea can make it more sensitive. "It's a complex interaction. Overall, we know that warming climate will lead to faster moving glaciers and less ice on Greenland. But how fast this happens, and to what extent, remains a key research topic," says Stranne.
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Climate
| 2,021 |
April 12, 2021
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https://www.sciencedaily.com/releases/2021/04/210412101851.htm
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Policy decisions will affect coastal communities' risk more than climate change
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Coastal communities face increasing danger from rising water and storms, but the level of risk will be more closely tied to policy decisions regarding development than the varying conditions associated with climate change, new research by Oregon State University suggests.
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The findings, published in the journal Professor Peter Ruggiero of OSU's College of Earth, Ocean, and Atmospheric Sciences and John Bolte, chair of OSU's Biological and Ecological Engineering program, led the study, which employed a modeling platform known as Envision to quantify the expected effects of flooding and erosion on buildings and infrastructure as well as beach accessibility through the remainder of the 21st century.Using data from Tillamook County along the northern Oregon coast, the researchers plugged into Envision information on landscape characteristics, population growth, development, water level, coastal change models, policy narratives and climate change scenarios.In a set of analyses involving many variables, the most important takeaway is the power of policy measures to positively or negatively affect a coastal community's climate risk level, Ruggiero said.Those measures include the construction of protective structures between the beach face and the shoreline; adding sediment to beaches where access in front of those structures has been lost; removing or relocating buildings repeatedly affected by coastal hazards and turning hazard zones into conservation areas; constructing new buildings well above the base flood elevation established by the Federal Emergency Management Agency; and preventing new development in hazard zones even if those areas are within urban/community growth boundaries.The model considered the effects of continuing current development policies, implementing only policies designed to combat environmental changes, realigning policies to be more consistent with a changing environment, and relaxing current policies such that development takes precedence over protecting coastal resources, beach access and everything else."The combination of climate change and development pressures has the potential to significantly increase the effects of flooding and erosion on coastal populations," Ruggiero said. "The strategies used to adapt to these impacts have the potential to either improve or exacerbate exposure to hazards, and our modeling results suggest that adaptation policies implemented in response to coastal hazards will have a greater impact on community exposure than the range of variability associated with climate change."He added that no alternative produced by the model represents a specific forecast for Tillamook County but rather provides a range of results for decision-makers there and in other communities to use to try to limit the uncertainty inherent in climate change adaptation planning."Implementing policies for which the outcome is less certain might not be as desirable as implementing one that's projected to positively impact one or two important metrics to the stakeholders under all climate scenarios," Ruggiero said. "Understanding the impacts of decisions and climate both individually and coupled within scenarios can potentially allow for better decision-making regarding adaptation."The National Oceanic and Atmospheric Administration and Oregon Sea Grant supported this research. The collaborators included OSU graduate students Alexis Mills, Katherine Serafin and Eva Lipiec.
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Climate
| 2,021 |
April 9, 2021
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https://www.sciencedaily.com/releases/2021/04/210409145854.htm
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Unsettling currents: Warm water flowing beneath the 'Doomsday Glacier'
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For the first time, researchers have been able to obtain data from underneath Thwaites Glacier, also known as the "Doomsday Glacier." They find that the supply of warm water to the glacier is larger than previously thought, triggering concerns of faster melting and accelerating ice flow.
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With the help of the uncrewed submarine Ran that made its way under Thwaites glacier front, the researchers have made a number of new discoveries. Professor Karen Heywood of the University of East Anglia commented:"This was Ran's first venture to polar regions and her exploration of the waters under the ice shelf was much more successful than we had dared to hope. We plan to build on these exciting findings with further missions under the ice next year."The submersible has, among other things, measured the strength, temperature, salinity and oxygen content of the ocean currents that go under the glacier.Global sea level is affected by how much ice there is on land, and the biggest uncertainty in the forecasts is the future evolution of the West Antarctic Ice Sheet, says Anna Wåhlin, professor of oceanography at the University of Gothenburg and lead author of the new study now published in Science Advances.The ice sheet in West Antarctica accounts for about ten percent of the current rate of sea level rise; but also the ice in West Antarctica holds the most potential for increasing that rate because the fastest changes worldwide are taking place in the Thwaites Glacier. Due to its location and shape, Thwaites is particularly sensitive to warm and salty ocean currents that are finding their way underneath it.This process can lead to an accelerated melting taking place at the bottom of the glacier and inland movement of the so-called grounding zone, the area where the ice transitions from resting on the seabed to floating in the ocean.Due to its inaccessible location, far from research stations, in an area that is usually blocked by thick sea ice and many icebergs, there has been a great shortage of in situ measurements from this area. This means that there are big knowledge gaps for the ice-ocean boundary processes in this region.In the study, the researchers present the results from the submersible that measured strength, temperature, salinity and oxygen content of the ocean currents that go under the glacier."These were the first measurements ever performed beneath Thwaites glacier," says Anna Wåhlin.The results have been used to map the ocean currents underneath the floating part of the glacier. The researchers discovered that there is a deep connection to the east through which deep water flows from Pine Island Bay, a connection that was previously thought to be blocked by an underwater ridge.The research group has also measured the heat transport in one of the three channels that lead warm water towards Thwaites Glacier from the north. "The channels for warm water to access and attack Thwaites weren't known to us before the research. Using sonars on the ship, nested with very high-resolution ocean mapping from Ran, we were able to find that there are distinct paths that water takes in and out of the ice shelf cavity, influenced by the geometry of the ocean floor" says Dr Alastair Graham, University of Southern Florida.The value measured there, 0.8 TW, corresponds to a net melting of 75 km3 of ice per year, which is almost as large as the total basal melt in the entire ice shelf. Although the amount of ice that melts as a result of the hot water is not much compared to other global freshwater sources, the heat transport has a large effect locally and may indicate that the glacier is not stable over time.The researchers also noted that large amounts of meltwater flowed north away from the front of the glacier.Variations in salinity, temperature and oxygen content indicate that the area under the glacier is a previously unknown active area where different water masses meet and mix with each other, which is important for understanding the melting processes at the base of the ice.The observations show warm water approaching from all sides on pinning points, critical locations where the ice is connected to the seabed and give stability to the ice shelf. Melting around these pinning points may lead to instability and retreat of the ice shelf and, subsequently, the upstream glacier flowing off the land. Dr Rob Larter of the British Antarctic Survey commented:"This work highlights that how and where warm water impacts Thwaites Glacier is influenced by the shape of the sea floor and the ice-shelf base as well as the properties of the water itself. The successful integration of new sea-floor survey data and observations of water properties from the Ran missions shows the benefits of the multidisciplinary ethos within the International Thwaites Glacier Collaboration.""The good news is that we are now, for the first time, collecting data that is necessary to model the dynamics of Thwaite's glacier. This data will help us better calculate ice melting in the future. With the help of new technology, we can improve the models and reduce the great uncertainty that now prevails around global sea level variations." says Anna Wåhlin.
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Climate
| 2,021 |
April 9, 2021
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https://www.sciencedaily.com/releases/2021/04/210409104505.htm
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Abrupt ice age climate changes behaved like cascading dominoes
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Throughout the last ice age, the climate changed repeatedly and rapidly during so-called Dansgaard-Oeschger events, where Greenland temperatures rose between 5 and 16 degrees Celsius in decades. When certain parts of the climate system changed, other parts of the climate system followed like a series of dominos toppling in succession. This is the conclusion from an analysis of ice-core data by a group of researchers that included postdoc Emilie Capron and associate professor Sune Olander Rasmussen from the Section for the Physics of Ice, Climate and Earth at the Niels Bohr Institute, University of Copenhagen, in Denmark. This discovery, just published in the journal
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Understanding abrupt climate changes in the past is critical to our ability to confidently predict whether something similar will occur today or in the near future.Over the last several decades, this has led climate scientists to search for causal relationships of abrupt climate change during the ice age when Greenland temperatures repeatedly rose by as much as 16 degrees Celsius in just decades before slowly falling back to normal ice-age levels."Many studies have tried to answer this long-standing question: Which part of the climate system changed first when these approximately 30 abrupt climate changes, called Dansgaard-Oeschger events, began? Was it, for example, the ocean currents in the North Atlantic, the wind and rainfall patterns in the Northern Hemisphere, or the spread of sea ice in the Arctic that triggered climate change?" says ice-core scientist Emilie Capron from the Niels Bohr Institute (University of Copenhagen) and the Institute of Environmental Geosciences (CNRS/Université Grenoble Alpes/IRD/Grenoble INP), who led the study now published in This new analysis reveals a surprisingly diverse set of dynamics within the Dansgaard-Oeschger events. The same physical processes changed together like a row of cascading dominoes, but surprisingly, neither the rate of change nor the order of the processes were the same from one event to the other.The team of researchers used data from two parallel Greenland ice cores that spanned the last ice age to create an image of a typical Dansgaard-Oeschger event and to determine in what order the parts of the climate system changed at the onset of the abrupt climate transitions.The goal is to be able to transfer this knowledge of the past to today's climate and use the fingerprint of past climate change as a kind of warning signal for possible abrupt climate changes in the future.The analysis, funded by the EU as a Marie Sk?odowska-Curie Action and from a research grant from the Carlsberg Foundation, showed that changes in different parts of the climate system -- ocean currents, sea-ice and wind patterns -- were so closely intertwined that they likely triggered and reinforced each other, and led to these reoccurring abrupt climate changes.The results led the international team of scientists to compare the ice-core data with new results from climate model simulations of the last ice age developed by co-author Guido Vettoretti, postdoc at the Niels Bohr Institute. This IPCC-class of climate model is the same type as those used to make projections of future climate change. The comparison revealed that the model showed the same type of entangled behaviour of sea ice, strength of ocean currents, and wind and precipitation patterns.This is positive news in that it increases our confidence that these complex models demonstrably capture the physical processes needed to simulate these past abrupt climate changes. However, the result is also worrisome: One of the climate dominoes that could disrupt the entire system during the ice age was the extent of sea-ice cover in the North Atlantic, and the modern extent of sea ice has been declining at a significant rate since the 1980s, highlighting the risk of a similar domino effect due to human-made climate change.Unfortunately, our understanding of the interplay between the many parts of the Earth's climate system is insufficient to allow us to assess the risk of similar occurrences of abrupt climate change in the future.Likewise, following the domino analogy: We do not know to what extent the initial conditions of the dominoes are different in today's climate system compared to the situation during the last ice age."In any case, the results emphasize the importance of trying to limit climate change by, for example, cutting anthropogenic emissions of CO
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Climate
| 2,021 |
April 8, 2021
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https://www.sciencedaily.com/releases/2021/04/210408153638.htm
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Researchers illuminate mystery of sea turtles' epic migrations
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"Not all those who wander are lost ... " -- J.R.R. Tolkien
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Known as "the lost years," it is a little-understood journey that unfolds over thousands of miles and as much as two decades or more. Now, a Stanford-led study illuminates secrets of the North Pacific loggerhead turtles' epic migration between their birthplace on the beaches of Japan and reemergence years later in foraging grounds off the coast of Baja California. The study, published April 8 in "For decades, our ability to connect the migratory dots for this endangered species has remained elusive," said study lead author Dana Briscoe, who was a research associate at the Stanford Woods Institute for the Environment during the research and now works at the Cawthron Institute, New Zealand's largest independent marine science organization. "This work builds on the backbone of exceptional research about these 'lost years,' and for the first time ever we are excited to provide evidence of a 'thermal corridor' to explain a longstanding mystery of one of the ocean's greatest migrants."Wildlife seekers thrill to the sight of sea turtles, but ship traffic, fishing nets and other perils have been less kind. The International Union for Conservation of Nature lists six of the seven sea turtle species as critically endangered, endangered or vulnerable.Despite scientific advancements in core habitat use, we still know precious little about the movement of turtles and other long-lived sea creatures between disparate locations. This knowledge gap makes it impossible to effectively assess and protect these species.The researchers wanted to know how and why some loggerheads travel to the western coastline of North America while others remain in the central Pacific Ocean. How is it that some sea turtles -- creatures highly sensitive to temperature -- can cross a frigid zone called the Eastern Pacific Barrier between the two ocean regions that normally stops most creatures in their tracks?To unlock that mystery, the researchers created the largest dataset on satellite-tagged loggerhead sea turtles ever compiled, employed sophisticated remote sensing oceanographic techniques and collected one of the first detailed records of sea turtle aging and stable isotope testing -- a bone analysis that can be used to provide information about an animal's life. The work relied upon decades of research by the international team of scientists.They started by looking at a 15-year study tracking the movements of more than 200 turtles tagged with satellite tracking devices. Six of the turtles caught the researchers' attention because -- unlike their peers -- they made distinct movements toward the North American coast. Adding to the intrigue, the "sentinels," as the researchers called them, made their journey during the early spring months. A look at remotely sensed ocean conditions for the time period showed that the farthest-roaming of the sentinels swam through water significantly warmer than their peers had confronted on their travels.A bigger picture analysis involved identifying the years loggerheads arrived in Baja California by measuring stable isotope "fingerprints" in the bones of sea turtles stranded on beaches there. Because like us, turtles are what they eat, these stable isotope signatures can reveal when the turtles transitioned from the open sea to the coast. The analysis showed significantly greater annual numbers of eastward-bound sea turtles during warm ocean conditions.The likely cause, according to the researchers: the development of a "thermal corridor" from unusually warm sea surface temperatures due to El Niño and other intermittent warming conditions that allowed the turtles to cross the Eastern Pacific Barrier to coastal foraging grounds.The corridor was present during the late spring and summer, and was also preceded by early warming of temperatures in the months before it opened. Such anomalous conditions, especially if sustained for several months, may provide key environmental cues to sea turtles and other animals concentrated in the eastern edge of the central Pacific that the thermal corridor is opening. Studies combining data from loggerhead aerial surveys, at-sea-sightings, stranding records and tissue samples supported the hypothesis.The phenomenon may be part of a trend. As the planet undergoes unprecedented climate changes, locations once considered impassable obstacles to species movements, like the Eastern Pacific Barrier, are being redefined. This, in turn, is shifting the distributions and migratory pathways of creatures ranging from sea birds to white sharks and presenting new conservation challenges.For the North Pacific loggerhead, the trend could mean higher exposure to bycatch -- unintentional fisheries harvest -- off the Baja California coast and other potentially important North American foraging grounds, including the Southern California Bight. The study provides important insights, such as an understanding of how animal movements relate to climate variation, that could help predict when sea turtles and other protected species could be vulnerable to such threats.The researchers caution that their multi-year dataset represents only a snapshot of an important developmental period for sea turtles. The small number of turtles that moved into the eastern North Pacific limits the ability to fully test the study's hypothesis under varying conditions. To do that, the researchers call for more satellite tagging and stable isotope studies of turtle bones in this region."Understanding how and why species like the North Pacific loggerhead move among habitats is crucial to helping them navigate threats," said study senior author Larry Crowder, the Edward Ricketts Provostial Professor at Stanford's Hopkins Marine Station. "Emerging technologies and analyses can help illuminate these journeys."Funding for this study provided by the Crowder Lab at Stanford's Hopkins Marine Station, the National Marine Fisheries Service, the National Academy of Sciences, Stanford's Department of Biology and the Stanford Woods Institute for the Environment.
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Climate
| 2,021 |
April 8, 2021
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https://www.sciencedaily.com/releases/2021/04/210408131455.htm
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Corals carefully organize proteins to form rock-hard skeletons
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Charles Darwin, the British naturalist who championed the theory of evolution, noted that corals form far-reaching structures, largely made of limestone, that surround tropical islands. He didn't know how they performed this feat.
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Now, Rutgers scientists have shown that coral structures consist of a biomineral containing a highly organized organic mix of proteins that resembles what is in our bones. Their study, published in the "Our research revealed an intricate network of skeletal proteins that interact spatially, which likely applies to all stony corals," said Manjula P. Mummadisetti, who led the research while she was a postdoctoral associate in the Rutgers Environmental Biophysics and Molecular Ecology Laboratory led by senior author Paul G. Falkowski. She is now a senior scientist at AVMBioMed in Pottstown, Pennsylvania. "It's important to understand the mechanisms of coral biomineralization and how these invaluable animals persist during the era of anthropogenic climate change.""Our findings suggest that corals will withstand climate change caused by human activities, based on the precision, robustness and resilience of their impressive process for forming rock-hard skeletons," said Falkowski, a Distinguished Professor in the School of Arts and Sciences and School of Environmental and Biological Sciences at Rutgers University-New Brunswick.Coral reefs protect shorelines threatened by erosion and storms, and provide fish habitat, nursery and spawning grounds. Indeed, coral reefs provide food for about a half-billion people, who also depend on them to make a living. However, warming ocean waters from climate change put corals at risk from deadly bleaching and disease. More acidic ocean waters, sea-level rise, unsustainable fishing, vessels that damage reefs, invasive species, marine debris and tropical cyclones pose additional threats, according to the National Oceanic and Atmospheric Administration.Rutgers scientists studied the spatial interactions of the proteins embedded within the skeleton of Predicting the survival of corals based on how they adapted to global climate change over millions of years requires understanding, among other things, how they build reefs by secreting calcium carbonate. That process is called biomineralization.The scientists showed that several proteins work together to create optimal conditions for biomineralization. These proteins are not located randomly but are well-organized spatially, which the scientists detailed for the first time. The scientists revealed the spatial patterns as new mineral is formed between the living tissue of the animal and its base or an older skeleton.Jeana Drake, who earned a doctorate at Rutgers and coauthored the study, is now at the University of California, Los Angeles, and the University of Haifa.
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Climate
| 2,021 |
April 8, 2021
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https://www.sciencedaily.com/releases/2021/04/210408131452.htm
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Study calls for urgent climate change action to secure global food supply
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New Curtin University-led research has found climate change will have a substantial impact on global food production and health if no action is taken by consumers, food industries, government, and international bodies.
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Published in one of the highest-ranking public health journals, the Lead researcher John Curtin Distinguished Emeritus Professor Colin Binns, from the Curtin School of Population Health at Curtin University, said climate change has had a detrimental impact on health and food production for the past 50 years and far more needs to be done to overcome its adverse effects."The combination of climate change and the quality of nutrition is the major public health challenge of this decade and, indeed, this century. Despite positive advances in world nutrition rates, we are still facing the ongoing threat of climate change to our global food supply, with Sub-Saharan Africa and part of Asia most at risk" Professor Binns said."For the time being, it will be possible to produce enough food to maintain adequate intakes, using improved farming practices and technology and more equity in distribution, but we estimate that by 2050 world food production will need to increase by 50 per cent to overcome present shortages and meet the needs of the growing population."Our review recommends that by following necessary dietary guidelines and choosing foods that have low environmental impacts, such as fish, whole grain cereals, fruits, vegetables, legumes, nuts, berries, and olive oil, would improve health, help reduce greenhouse gases and meet the United Nations Sustainable Development Goals, which in turn would improve food production levels in the future."Professor Binns said that while climate change will have a significant effect on food supply, political commitment and substantial investment could go some way to reduce the effects and help provide the foods needed to achieve the Sustainable Development Goals."Some changes will need to be made to food production, nutrient content will need monitoring, and more equitable distribution will be required to meet the proposed dietary guidelines. It was also be important to increase breastfeeding rates to improve infant and adult health, while helping to reduce greenhouse gases and benefit the environment," Professor Binns said."Ongoing research will be vital to assessing the long-term impacts of climate change on food supply and health in order to adequately prepare for the future."
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Climate
| 2,021 |
April 8, 2021
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https://www.sciencedaily.com/releases/2021/04/210408112315.htm
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One-third of Antarctic ice shelf area at risk of collapse as planet warms
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More than a third of the Antarctic's ice shelf area could be at risk of collapsing into the sea if global temperatures reach 4°C above pre-industrial levels, new research has shown.
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The University of Reading led the most detailed ever study forecasting how vulnerable the vast floating platforms of ice surrounding Antarctica will become to dramatic collapse events caused by melting and runoff, as climate change forces temperatures to rise.It found that 34% of the area of all Antarctic ice shelves -- around half a million square kilometres -- including 67% of ice shelf area on the Antarctic Peninsula, would be at risk of destabilisation under 4°C of warming. Limiting temperature rise to 2°C rather than 4°C would halve the area at risk and potentially avoid significant sea level rise.The researchers also identified Larsen C -- the largest remaining ice shelf on the peninsula, which split to form the enormous A68 iceberg in 2017 -- as one of four ice shelves that would be particularly threatened in a warmer climate.Dr Ella Gilbert, a research scientist in the University of Reading's Department of Meteorology, said: "Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise. When they collapse, it's like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea."We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly. Previous research has given us the bigger picture in terms of predicting Antarctic ice shelf decline, but our new study uses the latest modelling techniques to fill in the finer detail and provide more precise projections."The findings highlight the importance of limiting global temperature increases as set out in the Paris Agreement if we are to avoid the worst consequences of climate change, including sea level rise."The new study, published in the Ice shelf vulnerability from this fracturing process was forecast under 1.5°C, 2°C and 4°C global warming scenarios, which are all possible this century.Ice shelves are permanent floating platforms of ice attached to areas of the coastline and are formed where glaciers flowing off the land meet the sea.Every summer, ice at the surface of the ice shelf melts and trickles down into small air gaps in the snow layer below, where it refreezes. However, in years when there is a lot of melting but little snowfall, the water pools on the surface or flows into crevasses, deepening and widening them until the ice shelf eventually fractures and collapses into the sea. If there is water collecting on the surface of the ice shelf, that suggests it could be vulnerable to collapse in this way.This is what happened to the Larsen B ice shelf in 2002, which fractured following several years of warm summer temperatures. Its collapse caused the glaciers behind the ice shelf to speed up, losing billions of tonnes of ice to the sea.The researchers identified the Larsen C, Shackleton, Pine Island and Wilkins ice shelves as most at-risk under 4°C of warming, due to their geography and the significant runoff predicted in those areas.Dr Gilbert said: "If temperatures continue to rise at current rates, we may lose more Antarctic ice shelves in the coming decades."Limiting warming will not just be good for Antarctica -- preserving ice shelves means less global sea level rise, and that's good for us all."
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Climate
| 2,021 |
April 8, 2021
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https://www.sciencedaily.com/releases/2021/04/210408112332.htm
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Colorado River basin due for more frequent, intense hydroclimate events
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In the vast Colorado River basin, climate change is driving extreme, interconnected events among earth-system elements such as weather and water. These events are becoming both more frequent and more intense and are best studied together, rather than in isolation, according to new research.
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"We found that concurrent extreme hydroclimate events, such as high temperatures and unseasonable rain that quickly melt mountain snowpack to cause downstream floods, are projected to increase and intensify within several critical regions of the Colorado River basin," said Katrina Bennett, a hydrologist at Los Alamos National Laboratory and lead author of the paper in the journal Another example of concurrent hydroclimate events might be low precipitation accompanied by high temperatures, which cause drought as an impact. Other factors such as low soil moisture or wildfire burn scars on steep slopes contribute to impacts."You never have just a big precipitation event that causes a big flood," Bennett said. "It results from a combination of impacts, such as fire, topography, and whether it was a wet or dry summer. That's the way we need to start thinking about these events."The Los Alamos study looked heat waves, drought, flooding, and low flows in climate scenarios taken from six earth-system models for the entire Colorado River basin. The basin spans portions of Wyoming, Colorado, New Mexico, Utah, Nevada, Arizona, and California.Using indicators such as maximum temperature, maximum precipitation, dry days, maximum and minimum streamflow, maximum and minimum soil moisture, and maximum evapotranspiration, the team ran the models for a historical period (1970-1999) and a projected future period (2070-2099). They studied the difference between the two periods (future minus historical) for events at four time scales: daily, monthly, seasonal, and annual.Overall, precipitation across the Colorado increased by 2.1 millimeters between the future and historical periods, with some models showing increases in precipitation and some showing decreases. Nonetheless, the team found that in all cases, precipitation changes still drove an increase in concurrent extreme events.Unsurprisingly, temperature increased across all six models and was an even stronger catalyst of events. Consistently across the entire basin, the study found an average temperature rise of 5.5 degrees Celsius between the future and historical periods.In every scenario, the number and magnitude of each type of extreme event increased on average across the Colorado River Basin for the future period compared to the historical period. These numbers were given as a statistical expression of the change in frequency between the historical and future period, not as a count of discrete events.Those increases have significant social, economic, and environmental implications for the entire region, which is a major economic engine for the United States. The study identified four critical watersheds in the Colorado basin -- the Blue River basin, Uncompahgre, East Taylor, Salt/Verde watersheds -- that are home to important water infrastructures, water resources, and hydrological research that would be particularly vulnerable to extreme events in the future.More than 40 million people depend on the Colorado River basin for water, and it directly supports $1.4 trillion in agricultural and commercial activity -- roughly one thirteenth of the U.S. economy, according to 2014 figures.In Utah, Colorado, Arizona, and New Mexico, flooding, drought, freezing events, wildfire, severe storms, and winter storms have cost approximately $40 billion between 1980-2020.This work was funded by the Early Career Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory.
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Climate
| 2,021 |
April 7, 2021
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https://www.sciencedaily.com/releases/2021/04/210407174313.htm
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Reflecting sunlight could cool the Earth's ecosystem
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Published in the
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Composed of climate scientists and ecologists from leading research universities internationally, the team found that more research is needed to understand the ecological impacts of solar radiation modification (SRM) technologies that reflect small amounts of sunlight back into space. The team focused on a specific proposed SRM strategy -- referred to as stratospheric aerosol intervention (SAI)) -- to create a sulfate aerosol cloud in the stratosphere to reduce a portion of incoming sunlight and radiation. In theory, this cloud could be controlled in size and location.SAI is like placing tiny reflective particles in the atmosphere to bounce a portion of the solar radiation back to space, so that some of the radiation does not reach -- and warm -- Earth.The team emphasizes that greenhouse gas emissions reduction and conservation of biodiversity and ecosystem functions must be the priority."We are just starting to consider the risks and benefits of geoengineering, and it's critical that we include ecosystems in cost-benefit studies," said Hellmann, director at the U of M Institute on the Environment. "We should only pursue geoengineering if its benefits strongly outweigh its downsides. Because our efforts to stem climate change are modest and slow, the case for considering geoengineering is growing, and this paper represents the ecologists chiming in to the geoengineering conversation."The complexity of cascading relationships between ecosystems and climate under SAI -- in combination with the timing, amount, length and termination of SAI scenarios -- means that SAI is not a simple thermostat that turns down the heat a couple of degrees. Other potential effects of SAI include shifts in rainfall and increases in surface UV rays. While SAI might cool an overheated Earth, it would not be able to counter all of the effects of rising atmospheric CO2, such as halting ocean acidification."When we approach complex questions like these, there is a broad scale, theoretical understanding of the inherent patterns of biodiversity across the surface of Earth, but this understanding is often informed by finer-scale experiments that test the biological and physical mechanisms underlying those patterns," said Phoebe Zarnetske, study co-lead and an associate professor in Michigan State University's Department of Integrative Biology and the Ecology, Evolution, and Behavior program."I hope the paper can convince ecologists that research about nature's responses to solar geoengineering is not just important, but also interesting -- touching on core ecological questions about topics as varied as photosynthesis and animal migration," said U of M alum Shan Kothari, who contributed to the study during his time at the College of Biological Sciences before going to the University of Montreal.Kothari said that an example of how other scientists can consider the study's findings is to contemplate the unique conditions resulting from solar geoengineering scenarios that may aid or impede the ability for ecosystems to store carbon. He added that such research could help the international community consider solar geoengineering with a stronger awareness of the potential risks and benefits involved.
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Climate
| 2,021 |
April 7, 2021
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https://www.sciencedaily.com/releases/2021/04/210407135729.htm
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Genome sequencing reveals a new species of bumblebee
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While studying genetic diversity in bumblebees in the Rocky Mountains, USA, researchers from Uppsala University discovered a new species. They named it
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Bumblebees are vital for agriculture and the natural world due to their role in plant pollination. There are more than 250 species of bumblebee, and they are found mainly in northern temperate regions of the planet. Alarmingly, many species are declining due to the effects of climate change, and those with alpine and arctic habitats are particularly threatened. However, the full diversity of bumblebee species in these environments is still unknown.Matthew Webster's research group at Uppsala University, together with colleagues in the USA, studied genetic diversity in bumblebees in the Rocky Mountains, Colorado by collecting hundreds of samples and sequencing their genomes. Surprisingly, the data revealed the presence of a new species, which was indistinguishable in appearance to the species By comparing the genomes of These results indicate that the number of bumblebee species in arctic and alpine environments may be larger than previously thought. It is possible that mountainous terrain is conducive to speciation. Cold-adapted populations could become isolated at high altitudes during periods of warming in their evolutionary history, leading to the formation of new species. It is also possible that additional genome sequencing of bumblebees will reveal even more cryptic species that have so far gone undetected.
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Climate
| 2,021 |
April 7, 2021
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https://www.sciencedaily.com/releases/2021/04/210407093231.htm
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Aquatic ecosystems source of half of global methane emissions
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Direct human alterations to natural aquatic ecosystems can increase methane emissions, a new study has found.
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Atmospheric methane has tripled since pre-industrial times. It traps heat far more effectively than carbon dioxide and accounts for 25% of atmospheric warming to date. And much of that methane is coming from aquatic ecosystems, with human activities contributing to the emissions levels, a new paper published in The global contribution and importance of aquatic ecosystems as methane emitters has been underestimated, says Judith Rosentreter, postdoctoral associate at the Yale School of the Environment (YSE) who led the study with a team of 14 researchers worldwide.The study authors reviewed methane fluxes from 15 major natural, human-made, and human-impacted aquatic ecosystems and wetlands, including inland, coastal, and oceanic systems. They found that when methane emissions are combined from these aquatic ecosystems, they are potentially a larger source of methane than direct anthropogenic methane sources, such as agriculture or fossil fuel combustion. Aquatic ecosystems and wetlands contribute at least as much as half of the total methane emissions budget."An accurate accounting of the sources of methane from aquatic ecosystems, and if they are impacted by human activities, is important to understanding atmospheric methane concentrations,'' says Peter Raymond, professor of ecosystem ecology who co-authored the study.One issue that stood out is how humans have impacted methane emissions from aquatic sources."Anything human-driven or human-impacted had much higher fluxes than more natural sites,'' says Rosentreter, a Yale Institute for Biospheric Studies Hutchinson Fellow.Globally, rice cultivation releases more methane per year than all coastal wetlands, the continental shelf and open ocean combined. Fertilizer runoff causes nutrient-rich lakes and reservoirs to release methane. Coastal aquaculture farms have methane fluxes per area that are 7-430 times higher than from non-converted coastal habitats, such as mangrove forests, salt marshes or seagrasses.But the study notes that there are opportunities to reduce human-impacted emissions with the right management techniques."The intense methane emissions from aquatic ecosystems offers opportunities for intervention providing potential quick wins in reducing greenhouse emissions, provided the much large role per molecule emitted of methane compared to carbon dioxide,'' says study co-author Carlos M. Duarte, professor at King Abdullah University of Science and?Technology (KAUST) in Saudi Arabia.Fluctuating between flooded and non-flooded conditions in aquaculture farms and rice paddies; restoring tidal flow in degraded coastal wetlands; and reducing nutrient and organic matter in freshwater lakes, reservoirs, and rivers can all help reduce emissions, the study notes."Reducing methane emissions from aquatic systems will be an important part of stabilizing the Earth's temperature,'' says co-author Bradley Eyre Director, Centre for Coastal Biogeochemistry at Southern Cross University in Australia.Bringing awareness to the amount of methane emissions coming from aquaculture and other water systems can help inform new monitoring and measurements that identify where and how methane emissions are being produced and change over time."With this awareness is also the possibility of helping to keep our waters cleaner,'' Rosentreter says.
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Climate
| 2,021 |
April 6, 2021
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https://www.sciencedaily.com/releases/2021/04/210406120653.htm
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Mapping North Carolina's ghost forests from 430 miles up
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Emily Ury remembers the first time she saw them. She was heading east from Columbia, North Carolina, on the flat, low-lying stretch of U.S. Highway 64 toward the Outer Banks. Sticking out of the marsh on one side of the road were not one but hundreds dead trees and stumps, the relic of a once-healthy forest that had been overrun by the inland creep of seawater.
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"I was like, 'Whoa.' No leaves; no branches. The trees were literally just trunks. As far as the eye could see," said Ury, who recently earned a biology Ph.D. at Duke University working with professors Emily Bernhardt and Justin Wright.In bottomlands throughout the U.S. East Coast, trees are dying off as rising seas and higher storm surges push saltwater farther inland, poisoning soils far from shore.While these "ghost forests" are becoming a more common sight in North Carolina's coastal plain, scientists had only a rough idea of their extent. Now, satellite images are providing new answers.In a study published April 4 in the journal The images show that, between 1985 and 2019, 11% of the area's tree cover was taken over by ghost forests. Instead of mirroring the gradual pace of sea level rise, most of this spread occurred abruptly in the wake of extreme weather events such as hurricanes and droughts, which can concentrate salts or send them surging into the region's interior.The study focused on the Alligator River National Wildlife Refuge, which was established in 1984 to protect the area's unique forested wetlands and the endangered red wolves, red-cockaded woodpeckers and other wildlife that live there.Here, the Duke team is monitoring what Bernhardt and other researchers call "the leading edge of climate change."From 1900 to 2000, the sea rose about a foot in this part of coastal North Carolina, faster than the global average. By the end of this century, it could rise two to five feet more.Shrinking shorelines dominate most discussions of sea-level rise, as oceans submerge coastlines and chew away at beachfront property. Yet less talked about is what's happening farther inland.Long before beaches shrink and disappear under the rising sea, seawater starts creeping into low-lying regions.Most of the Alligator River National Wildlife refuge sits less than two feet above sea level, "which makes it all the more vulnerable to sea level rise," Ury said.Add to that the hundreds of miles of ditches and canals that crisscross the region. Built during the mid-1900s to drain water out, they now act as a conduit for seawater -- which is about 400 times saltier than freshwater -- to flow in.With no barriers in the way, seawater gets pushed inland through these channels, leaving its salty fingerprints on the soils. As the salt moves in, it draws water out of plant cells and strips seeds of their moisture, making it harder for new tree seedlings to sprout. Salt-sensitive tree species first fail to reproduce and eventually die off, as freshwater forest turns to salt marsh.Using pictures taken by 430-mile-high Landsat satellites, the team was able to map the spread of ghost forests in the refuge over time.Each pixel in the satellite images represents the wavelengths of light bouncing off the Earth below, in an area on the ground roughly the size of a baseball diamond.The team fed the satellite images to a computer algorithm, which in turn analyzed each pixel and determined whether it was dominated by dominated by pines, hardwoods, shrubs, grassy marsh, open water or dead trees. Any pixel with as many as 20 to 40 visibly dead trees present at once was labeled as ghost forest.The view from space changed over the 35 years of the study.More than three-fourths of the study area was covered in trees in 1985. Since then, even without any logging or development, the refuge has lost more than 46,950 acres of forest, or a quarter of its 1985 tree cover.More than half of these losses occurred in the interior of the refuge, more than a kilometer from any coast, the study revealed."It's not just the fringe that's getting wetter," Ury said.Of the more than 21,000 acres of ghost forest that formed between 1985 and 2019, the most noticeable die-off was in 2012. The area had just endured a five-year drought and then a potent strike by Hurricane Irene in 2011, when a 6-foot wall of seawater was pushed ashore. The storm surge swept across the refuge, cresting over Highway 264, more than 1.2 miles inland from the coast. Within months, entire stands of dying and downed trees were visible from space.What is happening in eastern North Carolina is happening elsewhere, too, the researchers say. In coastal regions across the globe, saltwater is starting to reach areas that haven't seen it before, even reducing crop yields and jeopardizing freshwater aquifers that people rely on for drinking water.The Duke team is collaborating with other researchers to expand their study to other parts of the Atlantic and Gulf coastal plains, from Cape Cod to Texas."Because of its geological location, North Carolina is just ahead of other coastal areas in terms of how far sea level rise has progressed," Ury said. "Lessons learned here could help manage similar transitions in other places," or pinpoint areas that are likely to be vulnerable in the future.
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Climate
| 2,021 |
April 6, 2021
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https://www.sciencedaily.com/releases/2021/04/210406092659.htm
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Droughts longer, rainfall more erratic over the last 50 years in most of Western US
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Dry periods between rainstorms have become longer and annual rainfall has become more erratic across most of the western United States during the past 50 years, according to a new study published by the U.S. Department of Agriculture's Agricultural Research Service and the University of Arizona.
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Against the backdrop of steadily warming temperatures and decreasing total yearly rainfall, rain has been falling in fewer and sometimes larger storms, with longer dry intervals between. Total yearly rainfall has decreased by an average of 0.4 inches over the last half century, while the longest dry period in each year increased from 20 to 32 days across the West, explained co-senior author Joel Biederman, a research hydrologist with the ARS Southwest Watershed Research Center in Tucson, Arizona."The greatest changes in drought length have taken place in the desert Southwest. The average dry period between storms in the 1970s was about 30 days; now that has grown to 45 days," Biederman said.Extreme droughts are also occurring more often in the majority of the West according to historical weather data as there has been an increase in the year-to-year variation of both total rainfall amounts and the duration of dry periods.Biederman emphasized the growing fluctuations in drought and rain patterns as the most significant change."Consistency of rainfall, or the lack of it, is often more important than the total amount of rain when it comes to forage continuing to grow for livestock and wildlife, for dryland farmers to produce crops, and for the mitigation of wildfire risks," Biederman said.The rate of increasing variability of rainfall within each year and between years also appears to be accelerating, with greater portions of the West showing longer drought intervals since 2000 compared to previous years.Notable exceptions to these drought patterns were seen in Washington, Oregon and Idaho and the Northern Plains region of Montana, Wyoming, and the most western parts of North and South Dakota. In these regions, the researchers found some increases in total annual rainfall and decreases in drought intervals. Together, these changes support what models have predicted as a consequence of climate change: a northward shift in the mid-latitude jet stream, which brings moisture from the Pacific Ocean to the western United States, according to Biederman.A critical aspect of this study is the use of actual rainfall data from 337 weather stations spread across the western United States. Biederman contrasted this with the more common use of "gridded" data, which relies on interpolations between reporting stations and tends to smooth out some of the variability revealed by this work."Fangyue Zhang, lead author of the manuscript and a post-doctoral researcher on our team, did the hard, painstaking work of compiling and analyzing data from more than 300 weather stations with complete daily records to reveal these changing drought and rainfall patterns," Biederman said."We were surprised to find widespread changes in precipitation have already occurred across large regions of the West. For regions such as the desert Southwest, where changes clearly indicate a trend towards longer, more erratic droughts, research is urgently needed to help mitigate detrimental impacts on ecosystem carbon uptake, forage availability, wildfire activity, and water availability for people," said co-senior author William K. Smith, assistant professor, University of Arizona.
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Climate
| 2,021 |
April 6, 2021
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https://www.sciencedaily.com/releases/2021/04/210406084057.htm
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Discovery is key to creating heat-tolerant crops
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By 2050 global warming could reduce crop yields by one-third. UC Riverside researchers have identified a gene that could put the genie back in the bottle.
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Warmer temperatures signal to plants that summer is coming. Anticipating less water, they flower early then lack the energy to produce more seeds, so crop yields are lower. This is problematic as the world's population is expected to balloon to 10 billion, with much less food to eat."We need plants that can endure warmer temperatures, have a longer time to flower and a longer growth period," said UCR botany and plant sciences professor Meng Chen. "But, to be able to modify plants' temperature responses, you first have to understand how they work. So, that's why identifying this gene that enables heat response is so important."The work that Chen and his colleagues did to uncover the heat-sensing gene was published this week in the journal They located the first gene, called HEMERA, two years ago. Then they did an experiment to see if they could identify other genes involved in controlling the temperature-sensing process.Ordinarily, plants react to shifts of even a few degrees in weather. For this experiment, the team began with a mutant Arabidopsis plant completely insensitive to temperature, and they modified it to once again become reactive.Examining the genes of this twice-mutated plant revealed the new gene, RCB, whose products work closely with HEMERA to stabilize the heat-sensing function. "If you knock out either gene, your plant is no longer sensitive to temperature," Chen said.Both HEMERA and RCB are required to regulate the abundance of a group of master gene regulators that serve multiple functions, reacting to temperature as well as light, and turning plants green. These proteins are distributed to two different parts of plant cells, the nucleus as well as organelles called chloroplasts.Going forward, Chen says his laboratory will focus on understanding how these two parts of the cell communicate and work together to achieve growth, greening, flowering, and other functions."When you change light or temperature, genes in both the nucleus and chloroplasts change their expression. We think HEMERA and RCB are involved coordinating gene expression between these two cell compartments," Chen said.Ultimately, the goal is to be able to modify temperature response to ensure the future of our food supply."We were excited to find this second gene," Chen said. "It's a new piece of the puzzle. Once we understand how it all works, we can modify it, and help crops cope better with climate change."
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Climate
| 2,021 |
April 6, 2021
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https://www.sciencedaily.com/releases/2021/04/210406092701.htm
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To intervene or not to intervene? That is the future climate question
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Nine of the hottest years in human history have occurred in the past decade. Without a major shift in this climate trajectory, the future of life on Earth is in question, which poses a new question: Should humans, whose fossil fueled society is driving climate change, use technology to put the brakes on global warming?
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Michigan State University community ecologist Phoebe Zarnetske is co-lead of the Climate Intervention Biology Working Group, a team of internationally recognized experts in climate science and ecology that is bringing science to bear on the question and consequences of geoengineering a cooler Earth.The group's paper, "Potential ecological impacts of climate intervention by reflecting sunlight to cool Earth," was published in the most recent issue of "There is a dearth of knowledge about the effects of climate intervention on ecology," said Zarnetske, associate professor in the Department of Integrative Biology in the MSU College of Natural Science and the paper's lead author. "As scientists, we need to understand and predict the positive and negative effects it could have on the natural world, identify key knowledge gaps and begin to predict what impacts it may have on terrestrial, marine and freshwater species and ecosystems if it were adopted in the future."Conversations in 2018 between Jessica Gurevitch, Distinguished Professor in the Department of Ecology and Evolution at Stony Brook University and working group co-lead, and Alan Robock, Distinguished Professor in the Department of Environmental Sciences at Rutgers University, gave rise to the pioneering group, which is more aware than most that geoengineering Earth's atmosphere is more than just a science fiction scenario.The costs and technology needed to reflect the sun's heat back into space are currently more attainable than other climate intervention ideas like absorbing carbon dioxide from the air. The working group anticipates its discussions and open access paper will encourage an explosion of scientific investigation into how a climate intervention strategy known as solar radiation modification, or SRM, in tandem with greenhouse gas emissions reduction, would affect the natural world.The feasibility of planetary wide SRM efforts hinge on accurate predictions of its myriad outcomes provided by the well-established computer simulations of the Geoengineering Model Intercomparison Project, or GeoMIP. The "While climate models have become quite advanced in predicting climate outcomes of various geoengineering scenarios, we have very little understanding of what the possible risks of these scenarios might be for species and natural systems," Gurevitch said. "Are the risks for extinction, species community change and the need for organisms to migrate to survive under SRM greater than those of climate change, or does SRM reduce the risks caused by climate change?""Most of the GeoMIP models only simulate abiotic variables, but what about all of the living things that are affected by climate and rely on energy from the sun?" Zarnetske said, who is also a faculty member of MSU's Ecology, Evolution and Behavior Program. "We need to better understand the possible impacts of SRM on everything from soil microorganisms to monarch butterfly migrations to marine systems."Zarnetske's Spatial and Community Ecology Lab, or SpaCE Lab, specializes in predicting how ecological communities respond to climate change across scales from the microcosm to the global, making it uniquely poised to assist the working group in illuminating vital data for future SRM scenarios such as stratospheric aerosol intervention, or SAI, the focus of the paper.SAI would reduce some of the sun's incoming radiation by reflecting sunlight back into space, such as what happens after large volcanic eruptions. Theoretically, it would be possible to continuously replenish the cloud and control its thickness and location to achieve a desired target temperature.But the paper reveals the under researched complexity of cascading relationships between ecosystem function and climate under different SAI scenarios. In fact, the scientists argue that climate change mitigation must continue regardless of whether SRM is adopted, and the question remains whether some or any SRM can be beneficial in addition to decarbonization efforts."Although SAI may cool Earth's surface to a global temperature target, the cooling may be unevenly distributed, affecting many ecosystem functions and biodiversity," Zarnetske said. "Rainfall and surface ultraviolet radiation would change, and SAI would increase acid rain and would not mitigate ocean acidification."In other words, SRM is not a magic bullet for solving climate change. Until the working group's efforts inspire new research into the effects of different climate intervention scenarios, SRM is more akin to a shot in the dark."Participating in this working group has been quite eye-opening for me," said Peter Groffman, ecosystem ecologist and professor at the Advanced Science Research Center at the CUNY Graduate Center and the Cary Institute of Ecosystem Studies. "I was unaware that modeling climate intervention was so advanced, and I think that climate modelers were unaware of the complexities of the ecological systems being affected. It is a strong reminder of the importance of the need for multidisciplinary analysis of complex problems in environmental science.""We hope that this paper will spark a lot more attention to this issue and greater cooperation between scientists in the fields of climate science and ecology," Gurevitch said.
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Climate
| 2,021 |
February 17, 2021
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https://www.sciencedaily.com/releases/2021/02/210217091030.htm
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Wintering bird communities track climate change faster than breeding communities in Europe and North America
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A study recently completed in Europe and North America indicates that the composition of wintering and breeding bird communities changes in line with global warming. However, wintering bird communities are considerably faster at tracking the changing climate compared to breeding communities.
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Climate change is driving species' distribution towards the poles and mountaintops, resulting in changes to bird communities. As a considerable share of birds are migratory species, with the distance they travel varying by species, the rate of change in bird communities is different in the breeding season and in the winter. A new Finnish-led study demonstrates for the first time that changes in bird communities are significantly faster in the winter than in the breeding season."Climate change is reshaping bird communities so that abundance of southern species increase, while the abundance of northern species is reduced," says Senior curator Aleksi Lehikoinen from the Finnish Museum of Natural History Luomus, which is part of the University of Helsinki.The faster change of bird communities in the winter is most likely results from the birds being less sedentary in their wintering areas than in their breeding areas. Some species are capable of migrating also in mid-winter, if the weather gets colder. In fact, a rise in temperature increased the annual rate of change for wintering bird communities. During the breeding season, individual birds are bound to a specific environment for several months, preventing them from migrating in the middle of breeding even if the weather changes."In Finland, wintering bird communities in particular have changed due to the rapid increase in abundance of southern species, such as the tufted duck, the blackbird and the goldfinch. As winters become warmer faster than summers, our winter bird communities will continue to change rapidly also in the future," Lehikoinen explains.The study examined changes in bird communities in eight countries in Europe as well as in the United States and Canada since the 1980s. While the dataset encompasses over 1,200 bird species and a broad range of bird communities, the results were largely similar for both continents."Overall, the study included observations of almost three billion birds. Without keen birdwatchers contributing on a voluntary basis, collecting such a dataset would be impossible," Lehikoinen says, offering praise.
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Climate
| 2,021 |
February 17, 2021
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https://www.sciencedaily.com/releases/2021/02/210217091022.htm
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A new, clearer insight into Earth's hidden crystals
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Geologists have developed a new theory about the state of Earth billions of years ago after examining the very old rocks formed in the Earth's mantle below the continents.
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Assistant Professor Emma Tomlinson from Trinity College Dublin and Queensland University of Technology's Professor Balz Kamber have just published their research in leading international journal, The seven continents on Earth today are each built around a stable interior called a craton, and geologists believe that craton stabilisation some 2.5 -- 3 billion years ago was critical to the emergence of land masses on Earth.Little is known about how cratons and their supporting mantle keels formed, but important clues can be found in peridotite xenoliths, which are samples of mantle that are brought to the Earth's surface by erupting volcanoes.Dr Tomlinson, from Trinity's School of Natural Sciences, said:"Many rocks from the mantle below old continents contain a surprising amount of silica -- much more than is found in younger parts of the mantle.""There is currently no scientific consensus about the reason for this."The new research, which looks at the global data for mantle peridotite, comes up with a new explanation for this observation.The research used a new thermodynamic model to calculate that the unusual mineralogy developed when very hot molten rock -- greater than 1700 °C -- interacted with older parts of the mantle and this caused the growth of silica-rich minerals."For more than 1 billion years, from 3.8 to 2.5 billion years ago, volcanoes also erupted very unusual lavas of very low viscosity -- lava that was very thin, very hot and often contained variable levels of silica," Dr Tomlinson added."Our modelling suggests that the unusual lavas were in fact the molten rocks that interacted with the mantle at great depth and this interaction resulted in the variable level of silica."Professor Kamber, QUT, said:"Both the silica-rich rocks in the deep mantle and the low viscosity volcanic rocks stopped being made by the Earth some 2.5 billion years ago. This timing is the boundary between the Archaean and Proterozoic eons -- one of the most significant breaks in Earth's geological timescale."What caused this boundary remains unknown, but the research offers a new perspective.Professor Kamber added:"This may have been due to a change in how the mantle was flowing. Once the mantle started slowly turning over all the way down to the core (2,900 km), the very high temperatures of the Archaean eon were no longer possible."
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Climate
| 2,021 |
February 17, 2021
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https://www.sciencedaily.com/releases/2021/02/210217091049.htm
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Crocodile evolution rebooted by Ice Age glaciations
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Crocodiles are resilient animals from a lineage that has survived for over 200 million years. Skilled swimmers, crocodiles can travel long distances and live in freshwater to marine environments. But they can't roam far overland. American crocodiles (Crocodylus acutus) are found in the Caribbean and Pacific coasts of the Neotropics but they arrived in the Pacific before Panama existed, according to researchers from McGill University.
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Over 3 million years ago, the formation of the Isthmus of Panama altered global ocean circulation, connecting North and South America and establishing the Caribbean Sea. This resulted in widespread mixing of species on the continent and separation in the seas. On land, mammals from North America such as mammoths, sabre-toothed cats, horses, and camels invaded South America, and strange mammals like giant ground sloths, armadillos, and opossums from South America invaded North America. This event is known as the Great American Interchange, and the opposite happened in the seas, where new species of corals, clams, and fishes evolved in the separated Pacific and Caribbean waters.The question a group of McGill and Panamanian researchers asked was: how distant are the Pacific and Caribbean populations from each other and does it match the geological record? Researchers have long suspected that American crocodiles living on the Pacific coast should have diverged genetically enough from Caribbean populations to become unique species."We assumed we would detect significant genetic differences between Pacific and Caribbean crocodile populations that were isolated for the past 3 million years," thought José Avila-Cervantes, a recent PhD graduate of McGill University under the supervision of Professor Hans Larsson.To test this, Avila-Cervantes captured and took blood samples of crocodiles from several populations living on both coasts of Panama. Back at McGill University, he sequenced their genomes to look for small variations in their DNA. He used the genetic differences to estimate how much evolutionary divergence and gene flow existed between populations. With this information, the team found that Pacific and Caribbean crocodile populations have been separated for only about 100,000 years."This time of separation is a far cry from the 3 million years we were expecting," said Professor Larsson, Director of the Redpath Museum at McGill. "But it did match the last interglacial period of the Ice Age."Glacial and interglacial cycles in the Ice Age mark periods of peak polar glaciations separated by relatively warm times. These warm times caused sea levels to rise over 100 meters globally compared to present-day levels. Using the record of Ice Age sea levels, Avila-Cervantes was able to reconstruct what Panama would have looked like during these peak cold and warm periods of the Ice Age."It surprised us to see that during the warm inter-glacial periods, most of Panama was underwater with the coasts separated by brackish lagoons, small rivers, and thin stretches of land," said Avila-Cervantes. "These are the reasons why we think crocodiles were able to pass from coast to coast freely and explain why their oldest genetic signature of separation coincides with this time." A second younger signature of genetic separation is timed to about 20,000 years ago and coincides with the last glaciation cycle that they found made Panama about twice as wide as it is today, and probably a good barrier for these crocodiles. "This is one of the first studies to implicate Ice Age glaciation-interglaciation cycles with the evolution of a tropical organism."Yet the researchers discovered there is some genetic divergence between the populations on each coast despite the frequent inter-glaciations, and this diversity is at risk due to habitat destruction from human development. "It was difficult to find any population living on the Pacific coast near the Panama Canal," said Avila-Cervantes.One of the best-preserved populations is in the middle of the Panama Canal on the Barro Colorado Island Nature Monument. "Preserving the population around this island may be our best chance to preserve the unique genetic signatures of Panamanian American crocodiles," said Professor Larsson. "Our study not only highlights the resilience of crocodiles to ancient climate changes and their great capacity to survive large geological events, but also their vulnerability to our voracious need to modify their environments."
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Climate
| 2,021 |
February 16, 2021
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https://www.sciencedaily.com/releases/2021/02/210216185858.htm
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Out of this world: Photosynthesis measured from space
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As most of us learned in school, plants use sunlight to synthesize carbon dioxide (CO
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Because of their ability to make valuable products from organic compounds like COA research team with the U.S. Department of Energy's Center for Advanced Bioenergy and Bioproducts Innovation (CABBI) at the University of Illinois Urbana-Champaign developed a product to accurately measure GPP: the SatelLite Only Photosynthesis Estimation Gross Primary Production (SLOPE GPP) product at a daily time step and field-scale spatial resolution.The team leveraged the Blue Waters supercomputer, housed at the U of I National Center for Supercomputing Applications (NCSA), in their research. Their paper was published in "Quantifying the rate at which plants in a given area process CO"Measuring photosynthesis is especially pertinent to agricultural ecosystems, where plant productivity and biomass levels are directly tied to crop yield and therefore food security. Our research directly applies to not only ecosystem service, but also societal well-being," said Chongya Jiang, a research scientist on the project.Of particular intrigue is the relevance of GPP monitoring to bioenergy agricultural ecosystems, where the crops' "factories" are specially designed to produce renewable biofuels. Quantifying COThe technology used in this experiment is cutting-edge. As its name suggests, it is purely derived from satellite data, and therefore completely observation-based as opposed to relying on complex, uncertain modeling methods.One example of an observation-based technology is solar-induced chlorophyll fluorescence (SIF), a weak light signal emitted by plants that has been used as a novel proxy for GPP. Inspired by their years-long ground observations of SIF, Guan's group developed an even more advanced method to improve GPP estimation: integrating a new vegetation index called "soil-adjusted near-infrared reflectance of vegetation" (SANIRv) with photosynthetically active radiation (PAR).SLOPE is built on this novel integration. SANIRv represents the efficiency of solar radiation used by vegetation, and PAR represents the solar radiation that plants can actually use for photosynthesis. Both metrics are derived from satellite observations.Through an analysis of 49 AmeriFlux sites, researchers found that PAR and SANIRv can be leveraged to accurately estimate GPP. In fact, the SLOPE GPP product can explain 85% of spatial and temporal variations in GPP acquired from the analyzed sites -- a successful result, and the best performance ever achieved benchmarked on this gold-standard data. As both SANIRv and PAR are "satellite only," this is an achievement that researchers have long been seeking but is just now being implemented in an operational GPP product.Existing processes to quantify GPP are inefficient for three key reasons: spatial (image-based) precision, temporal (time-based) precision, and latency (delay in data availability). The SLOPE GPP product created by Guan's team uses satellite images twice as sharp as most large-scale studies (measuring at 250 meters versus the typical >500 meters) and retrieves data on a daily cycle, eight times finer than the norm. More importantly, this new product has between one and three days latency, whereas existing datasets lag behind by months or even years. Finally, the majority of GPP products employed today are analysis- rather than observation-based -- the metrics they use to calculate GPP (e.g., soil moisture, temperature, etc.) are derived from algorithms rather than real-world conditions gleaned from satellite observations."Photosynthesis, or GPP, is the foundation for quantifying the field-level carbon budget. Without accurate GPP information, quantifying other carbon-related variables, such as annual soil carbon change, is much less reliable," Guan said. "The Blue Waters supercomputer made our peta-bytes computing possible. We will use this novel GPP data to significantly advance our ability to quantify agricultural carbon budget accounting, and it will serve as a primary input to constrain the modeling of soil organic carbon change for every field that requires soil carbon quantification. In addition to the SLOPE GPP data, similar methods allow us to generate GPP data at 10-meter and daily resolution to even enable sub-field precision agricultural management."
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Climate
| 2,021 |
February 16, 2021
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https://www.sciencedaily.com/releases/2021/02/210216133415.htm
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How icebergs really melt -- and what this could mean for climate change
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Icebergs are melting faster than current models describe, according to a new study by mathematicians at the University of Sydney. The researchers have proposed a new model to more accurately represent the melt speed of icebergs into oceans.
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Their results, published in Lead author and PhD student Eric Hester said: "While icebergs are only one part of the global climate system, our improved model provides us with a dial that we can tune to better capture the reality of Earth's changing climate."Current models, which are incorporated into the methodology used by the Intergovernmental Panel on Climate Change, assume that icebergs melt uniformly in ocean currents. However, Mr Hester and colleagues have shown that icebergs do not melt uniformly and melt at different speeds depending on their shape."About 70 percent of the world's freshwater is in the polar ice sheets and we know climate change is causing these ice sheets to shrink," said Mr Hester, a doctoral student in the School of Mathematics & Statistics."Some of this ice loss is direct from the ice sheets, but about half of the overall ice loss from Greenland and Antarctica happens when icebergs melt in the ocean, so understanding this process is important."Our model shows that icebergs are melting at faster rates than current models assume," he said.As well as its importance for modelling how ice sheets are changing, Mr Hester said his research will help us better understand the impact of ice melt on ocean currents."Ocean circulation is the reason that Britain isn't as cold as Alberta, Canada, despite being at similar latitudes," Mr Hester said.The Gulf Stream that takes warmer water from the tropics across the Atlantic keeps western Europe milder than it otherwise would be, he said."That current could shut down if too much freshwater is dumped into the system at once, so it's critical we understand the process of iceberg and ice sheet melt."Where and when the freshwater is released, and how the ocean is affected, in part depends on the speed at which icebergs melt.Co-author Dr Geoffrey Vasil from the University of Sydney said: "Previous work incorporating icebergs in climate simulations used very simple melting models. We wanted to see how accurate those were and whether we could improve on them."Mr Hester said their models -- confirmed in experiment -- and the observations of oceanographers show that the sides of icebergs melt about twice as fast as their base. For icebergs that are moving in the ocean, melting at the front can be three or four times faster than what the old models predicted."The old models assumed that stationary icebergs didn't melt at all, whereas our experiments show melting of about a millimetre every minute," Mr Hester said."In icebergs moving in oceans, the melting on the base can be up to 30 percent faster than in old models."The research shows that iceberg shape is important. Given that the sides melt faster, wide icebergs melt more slowly but smaller, narrower icebergs melt faster."Our paper proposes a very simple model that accounts for iceberg shape, as a prototype for an improved model of iceberg melting," Dr Vasil said.To test these models, the researchers developed the first realistic small-scale simulations of melting ice in salt water."We are confident this modelling captures enough of the complexity so that we now have a much better way to explain how icebergs melt," Mr Hester said.Dr Vasil, who is Mr Hester's PhD supervisor, said: "Before Eric started his PhD the computational tools to model these kinds of systems didn't really exist."Eric took a very simple prototype and made it work wonderfully on the complex ice-melting problem."Dr Vasil said that these methods can be applied to many other systems, including glaciers melting or the melting of frozen, saline sea ice."But it doesn't end there. His methods could also be used by astrobiologists to better understand ice moons like Saturn's Enceladus, a candidate for finding life elsewhere in the Solar System."
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Climate
| 2,021 |
February 16, 2021
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https://www.sciencedaily.com/releases/2021/02/210216114950.htm
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Biologists devise new way to assess carbon in the ocean
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A new USC study puts ocean microbes in a new light with important implications for global warming.
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The study, published Tuesday in the Surprisingly, most of the action involving carbon occurs not in the sky but underfoot and undersea. The Earth's plants, oceans and mud store five times more carbon than the atmosphere. It accumulates in trees and soil, algae and sediment, microorganisms and seawater."The ocean is a huge carbon reservoir with the potential to mitigate or enhance global warming," said Naomi Levine, senior author of the study and assistant professor in the biological sciences department at the USC Dornsife College of Letters, Arts and Sciences. "Carbon cycling is critical for understanding global climate because it sets the temperature, which in turn sets climate and weather patterns. By predicting how carbon cycling and storage works, we can better understand how climate will change in the future."Processes governing how organic matter -- decaying plant and animal matter in the environment akin to the material gardeners add to soil -- accumulates are critical to the Earth's carbon cycle. However, scientists don't have good tools to predict when and how organic matter piles up. That's a problem because a better reconciling of organic carbon can inform computer models that forecast global warming and support public policy.In recent years, scientists have offered three competing theories to explain how organic matter accumulates, and each has its limitations. For example, one idea is some organic matter is intrinsically persistent, similar to an orange peel. Sometimes carbon is too diluted so microbes can't locate and eat it, as if they're trying to find a single yellow jellybean in a jar full of white ones. And sometimes, the right microbe isn't in the right place at the right time to intercept organic matter due to environmental conditions.While each theory explains some observations, the USC study shows how this new framework can provide a much more comprehensive picture and explain the ecological dynamics important for organic matter accumulation in the ocean. The solution has wide utility.For example, it can help interpret data from any condition in the ocean. When linked into a full ecosystem model, the framework accounts for diverse types of microbes, water temperature, nutrients, reproduction rates, sunlight and heat, ocean depth and more. Through its ability to represent diverse environmental conditions worldwide, the model can predict how organic carbon will accumulate in various complex scenarios -- a powerful tool at a time when oceans are warming and the Earth is rapidly changing."Predicting why organic carbon accumulates has been an unsolved challenge," said Emily Zakem, a study co-author and postdoctoral scholar at USC Dornsife. "We show that the accumulation of carbon can be predicted using this computational framework."The tool can also potentially be used to model past ocean conditions as a predictor of what may be in store for the Earth as the planet warms largely due to humanmade greenhouse gas emissions.Specifically, the model is capable of looking at how marine microbes can flip the world's carbon balance. The tool can show how microbes process organic matter in the water column throughout a given year, as well as at millennial timescales. Using that feature, the model confirms -- as has been previously predicted -- that microbes will consume more organic matter and rerelease it as carbon dioxide as the ocean warms, which ultimately will increase atmospheric carbon concentrations and increase warming. Moreover, the study says this phenomenon can occur rapidly, in a non-linear way, once a threshold is reached -- a possible explanation for some of the whipsaw climate extremes that occurred in Earth's distant past."This suggests that changes in climate, such as warming, may result in large changes in organic carbon stores and that we can now generate hypotheses as to when this might occur," Levine said.Finally, the research paper says the new tool can model how carbon moves through soil and sediment in the terrestrial environment, too, though those applications were not part of the study.In addition to Zakem and Levine, the study's authors included B.B. Cael of the National Oceanography Centre in England.Funding for the research team comes from the Simons Foundation, Simons Collaboration on Principles of Microbial Ecology (#542389) to Levine; the Simons Postdoctoral Fellowship in Marine Microbial Ecology to Zakem; a National Environmental Research Council grant (#NER015953-1) and a European Union Horizon 2020 Research and Innovation Program grant (#820989) to Cael.
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Climate
| 2,021 |
February 16, 2021
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https://www.sciencedaily.com/releases/2021/02/210216114939.htm
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Ferns in the mountains
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Earth is home to millions of known species of plants and animals, but by no means are they distributed evenly. For instance, rainforests cover less than 2 percent of Earth's total surface, yet they are home to 50 percent of Earth's species. Oceans account for 71 percent of Earth's total surface but contain only 15 percent of Earth's species. What drives this uneven distribution of species on Earth is a major question for scientists.
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In a paper published February 16 in the The researchers relied on recently digitized natural history collections to map the diversity of life on earth and build a database of over one million fern specimens with longitude and latitude coordinates occurring all over the world. After an extensive cleaning of the database to remove records with poor coordinates roughly 800,000 occurrence records remained. They then divided the earth into one-degree latitude by longitude grid cells and determined the number of species occurring within each cell. The researchers discovered that the majority of fern species occur in eight principally montane hotspots: Greater Antilles, Mesoamerica, tropical Andes, Guianas, Southeastern Brazil, Madagascar, Malesia and East Asia."Natural history collections are the primary data for all biodiversity studies, and they are the backbone to this study," said Sundue. "Scientists have been making collections and curating them for hundreds of years. But only recently, the digitization of these records has allowed us to harness their collective power."Testo agreed, "There has been a large effort over the last decade to digitize the impressive collection of specimens contributed by thousands of collectors and experts in the field and deposited in museums or natural history collections. For this study we used over 800,000 digitized occurrence records for nearly 8,000 fern species."The research was conducted in multiple phases and each phase built upon the previous. "The first thing we wanted to know is where are the centers of ferns' biodiversity, and second, why?" Suissa said. "We wanted to understand the biogeographical patterns of fern diversity. Understanding these patterns in a major plant lineage like ferns, allows us to take a step towards understanding why there is an uneven distribution of species around the world."One major finding is that 58 percent of fern species occur in eight principally montane biodiversity hotspots that comprise only 7 percent of Earth's land area. They also found that within these hotspots, patterns of heightened diversity were amplified at elevations greater than 1000 meters above sea level."On a global scale we find a peak in species richness per area around 2000 to 3000 meters in elevation, roughly midway up some of these tropical mountains," explained Suissa. "And we think this is primarily due to a very unique ecosystem that occurs in this elevation band, which in the tropics is the cloud forest."While ferns grow in a variety of ecosystems, including moist shaded forest understories and rocky desert outcrops, many species are actually epiphytic, meaning they grow on the branches of trees. Suissa and colleagues believe these epiphytes explain the mid to upper elevation peak in species richness of ferns in the tropics.Once the researchers determined the biogeographical patterns of fern diversity, they investigated why these particular patterns exist. Examining ecological data, including climate and soil data, they showed that within each hotspot there was a strong correlation between increased climatic space and increased species richness and diversification; suggesting that ferns occurring in tropical mountains are forming new species more rapidly than those elsewhere."People tend to think of places such as the Amazon rainforest as biodiversity hotspots," said Suissa. "But for ferns, it is tropical and subtropical mountains that harbor a disproportionate number of rapidly diversifying species relative to the land area they occupy. Ferns may be speciating within these tropical mountain systems because of the variation in habitats that occur across elevational gradients. For instance, at the base of a tropical mountain it is hot all year round, and at the summit it is perennially cold. Essentially, these dynamics create many different ecosystems within a small geographic space."Unlike mountains in temperate regions, the tropics have very low temperature seasonality. This means that each ecosystem across an elevational transect in a tropical mountain remains roughly the same temperature year-round. Effectively, it is harder for plant and animal species to move between elevational zones if they are adapted to one spot on the mountain. Researchers think that these dynamics between the difference in climates at different elevations and the climatic stability within each elevational site allow for plants and animals to diversify more rapidly in tropical mountains.Going forward the researchers hope to conduct more small-scale population-based studies in young tropical mountains to physically test these hypotheses, and to hopefully also add more specimens and continue to expand digitization of museum collections for study.
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Climate
| 2,021 |
February 16, 2021
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https://www.sciencedaily.com/releases/2021/02/210216083102.htm
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Climate change likely drove the extinction of North America's largest animals
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A new study published in
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Before around 10,000 years ago, North America was home to many large and exotic creatures, such as mammoths, gigantic ground-dwelling sloths, larger-than-life beavers, and huge armadillo-like creatures known as glyptodons. But by around 10,000 years ago, most of North America's animals weighing over 44 kg, also known as megafauna, had disappeared. Researchers from the Max Planck Extreme Events Research Group in Jena, Germany, wanted to find out what led to these extinctions. The topic has been intensely debated for decades, with most researchers arguing that human overhunting, climate change, or some combination of the two was responsible. With a new statistical approach, the researchers found strong evidence that climate change was the main driver of extinction.Since the 1960's, it has been hypothesized that, as human populations grew and expanded across the continents, the arrival of specialized "big-game" hunters in the Americas some 14,000 year ago rapidly drove many giant mammals to extinction. The large animals did not possess the appropriate anti-predator behaviors to deal with a novel, highly social, tool-wielding predator, which made them particularly easy to hunt. According to proponents of this "overkill hypothesis," humans took full advantage of the easy-to-hunt prey, devastating the animal populations and carelessly driving the giant creatures to extinction.Not everyone agrees with this idea, however. Many scientists have argued that there is too little archaeological evidence to support the idea that megafauna hunting was persistent or widespread enough to cause extinctions. Instead, significant climatic and ecological changes may have been to blame.Around the time of the extinctions (between 15,000 and 12,000 years ago), there were two major climatic changes. The first was a period of abrupt warming that began around 14,700 years ago, and the second was a cold snap around 12,900 years ago during which the Northern Hemisphere returned to near-glacial conditions. One or both of these important temperature swings, and their ecological ramifications, have been implicated in the megafauna extinctions."A common approach has been to try to determine the timing of megafauna extinctions and to see how they align with human arrival in the Americas or some climatic event," says Mathew Stewart, co-lead author of the study. "However, extinction is a process -- meaning that it unfolds over some span of time -- and so to understand what caused the demise of North America's megafauna, it's crucial that we understand how their populations fluctuated in the lead up to extinction. Without those long-term patterns, all we can see are rough coincidences."To test these conflicting hypotheses, the authors used a new statistical approach developed by W. Christopher Carleton, the study's other co-lead author, and published last year in the The major problem with the previous approach is that it blends the uncertainty associated with radiocarbon dates with the process scientists are trying to identify."As a result, you can end up seeing trends in the data that don't really exist, making this method rather unsuitable for capturing changes in past population levels. Using simulation studies where we know what the real patterns in the data are, we have been able to show that the new method does not have the same problems. As a result, our method is able to do a much better job capturing through-time changes in population levels using the radiocarbon record," explains Carleton.The authors applied this new approach to the question of the Late Quaternary North American megafauna extinctions. In contrast to previous studies, the new findings show that megafauna populations fluctuated in response to climate change."Megafauna populations appear to have been increasing as North American began to warm around 14,700 years ago," states Stewart. "But we then see a shift in this trend around 12,900 years ago as North America began to drastically cool, and shortly after this we begin to see the extinctions of megafauna occur."And while these findings suggest that the return to near glacial conditions around 12,900 years ago was the proximate cause for the extinctions, the story is likely to be more complicated than this."We must consider the ecological changes associated with these climate changes at both a continental and regional scale if we want to have a proper understanding of what drove these extinctions," explains group leader Huw Groucutt, senior author of the study. "Humans also aren't completely off the hook, as it remains possible that they played a more nuanced role in the megafauna extinctions than simple overkill models suggest."Many researchers have argued that it is an impossible coincidence that megafauna extinctions around the world often happened around the time of human arrival. However, it is important to scientifically demonstrate that there was a relationship, and even if there was, the causes may have been much more indirect (such as through habitat modification) than a killing frenzy as humans arrived in a region.The authors end their article with a call to arms, urging researchers to develop bigger, more reliable records and robust methods for interpreting them. Only then will we develop a comprehensive understanding of the Late Quaternary megafauna extinction event.
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Climate
| 2,021 |
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