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October 16, 2020
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https://www.sciencedaily.com/releases/2020/10/201015173135.htm
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Fraction of money earmarked for COVID-19 recovery could boost climate efforts
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Global stimulus plans for economic recovery after the pandemic could easily cover climate-friendly policies, suggests new study.
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Governments worldwide are planning stimulus packages to boost the economy following the disruptions caused by the COVID-19 pandemic. So far, more than $12 trillion USD have been pledged in such packages. This response is three times larger than the 2008-2009 global financial crisis recovery spending, and represents around 15 percent of global gross domestic product (GDP).A new analysis published today in The Paris Agreement aims to limit the average global temperature rise this century to well below 2°C above pre-industrial temperatures and to pursue efforts to keep it at 1.5°C. This will require a reduction in the use of fossil fuels, a shift to low-carbon renewable sources of energy, such as solar and wind power, and large improvements in energy efficiency.However, current efforts by governments worldwide are insufficient to reach the Paris Agreement goals. Instead, today's policies are leading us towards a world 3°C above pre-industrial averages. These higher temperatures will bring greater risks and more severe impacts, such as droughts, flooding and storms.The new analysis shows that an ambitious path to a 1.5°C world is well within reach if just a fraction of COVID-19 funding is invested in a 'climate-positive' recovery, with the dual aims of stimulating the global economy and accelerating the deployment of low-carbon energy supply and energy efficiency measures. This could be achieved, for example, via direct stimulus and investments as well as via supporting policies such as incentives and rebates.Senior author Dr Joeri Rogelj, from the Grantham Institute -- Climate Change and the Environment at Imperial, said: "Our findings show that investing in solutions to limit warming to 1.5°C is well within budget. In fact, the increase in low-carbon energy investments required over the next five years to move the world on track to meet the Paris Agreement targets is about eight times smaller than the total current COVID-19 stimulus."First author Marina Andrijevic, from Climate Analytics and Humboldt University, said: "If just a fraction of this money was invested in climate-positive recovery plans, the world could achieve net zero carbon energy by mid-century. This is not about diverting money from COVID-19 stimulus or other low-carbon investments in industry, research and development, but providing for the win-win solution of a boosted economy that simultaneously helps our efforts to stall climate change."Few countries have stated in full detail what they will use their recovery packages for, but immediate priorities will likely be to support healthcare systems, preserve livelihoods and stabilise employment. Beyond these, governments will be looking for investments that can foster economic recovery over the longer term.Several reports, including a survey of over 230 experts worldwide, have shown how a green recovery can support this goal by providing both short- and long-term benefits, including job creation and lowering the investment risk of green technologies.Dr Rogelj added: "Climate-positive recovery packages provide many benefits governments are looking for to get out of this crisis: they can boost employment and stimulate innovation, thus accelerating the development of technologies required for a global low-carbon transformation."The team's analysis shows that a climate-positive recovery also needs a strong, near-term focus on actively avoiding a polluting recovery, such as stimulus packages that bail out fossil fuels. Investments in these sectors are poised to continue in the coming years, but there is strong evidence for redirecting this funding to a climate-positive recovery and for supporting the transition by other means, such as reskilling employees.The analysis shows that this will be easier for some countries than others. The US and the European Union have pledged the most in post-pandemic recovery, and also need to invest the least proportionally in low-carbon energy to be on track to reach the Paris Agreement goals. Meanwhile, emerging economies like India have put forward less funding for pandemic recovery, but require proportionally more investments to provide their populations with reliable, clean and affordable energy.Co-author Dr David McCollum, from the Electric Power Research Institute and the University of Tennessee, said: "The differing situations between developed and emerging economies in these times of crisis remind us of the need to look beyond borders and to collaborate internationally so that a climate-positive recovery benefits everyone, everywhere."
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Climate
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October 15, 2020
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https://www.sciencedaily.com/releases/2020/10/201015173116.htm
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Researchers find diverse communities comprise bacterial mats threatening coral reefs
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Researchers are learning more about the brightly colored bacterial mats threatening the ecological health of coral reefs worldwide. In new research released this month, a Florida State University team revealed that these mats are more complex than scientists previously knew, opening the door for many questions about how to best protect reef ecosystems in the future.
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FSU Assistant Professor of Biological Science Sophie McCoy and doctoral student Ethan Cissell published their findings in the journal "By targeting the full biological diversity of these mat communities on reefs, and by studying the transcriptome, which gives us information about which biochemical processes are being used by those organisms, we're opening the door to a more complete understanding of the entire ecological role of mats," McCoy said.Though these cyanobacterial mats have been examined in the past, scientists focused on characterizing the cyanobacteria. Cissell and McCoy found that cyanobacteria only made up about 47.57% of the mats. Their analysis showed that mats also contained a type of algae called diatoms, fungi, a single cell organism called archaea, viruses and other forms of bacteria."We know from other well-characterized systems that cyanobacteria, even in bloom-forming scenarios, associate with a diversity of other microorganisms that make significant and unique contributions to the overall dynamics and ecophysiology of these cyanobacteria-dominated consortia," Cissell said. "We set out to determine if similar associations are found in proliferating cyanobacterial mats on coral reefs."Cyanobacterial mats have posed a huge problem for coral reef health. Coral reef bacteria have always played an important role in these ecological communities, but the growth -- largely attributed to local and global climate stressors -- has threatened to totally snuff out the life of precious corals.Previously, the bacteria covered about 1% of reefs, but that has grown to 20 to 30% in some places.Researchers said this greater understanding of the communities comprising the mats leads to more questions about how the mats form and grow."What this means is that the mechanisms controlling mat bloom dynamics on coral reefs are likely more complex than previously thought," Cissell said. "These data we present provide important baselines for future mechanistic-based exploration of the processes driving the growth, persistence, and decline of benthic cyanobacterial mats."McCoy and Cissell conducted 29 diving expeditions in Bonaire, an island municipality of the Netherlands off the coast of Venezuela, for the project. They are currently conducting genetic sequencing on mat samples to get a better understanding of daily patterns of the communities comprising the mat. They are also examining samples taken from a dying mat to better understand compositional and functional shifts associated with mat death.Their work was supported by the National Science Foundation and the Phycological Society of America.
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Climate
| 2,020 |
October 15, 2020
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https://www.sciencedaily.com/releases/2020/10/201015134210.htm
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Phosphate polymer forms a cornerstone of metabolic control
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In a changing climate, understanding how organisms respond to stress conditions is increasingly important. New work led by Carnegie's Arthur Grossman and Emanuel Sanz-Luque could enable scientists to engineer the metabolism of organisms to be more resilient and productive in a range of environments.
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Their research focuses on polyphosphate, an energy-rich polymer of tens to hundreds phosphate groups which is conserved in all kingdoms of life and is integral to many cellular activities, including an organism's ability to respond to changing environmental conditions."The ways in which polyphosphate synthesis and mobilization can be integrated into a myriad of biological processes in a range of photosynthetic and non-photosynthetic organisms and various cell types has been difficult to unravel," Grossman said. "Polyphosphate plays a critical role in responding to environmental stresses, including high temperatures, exposure to toxic metals and, of particular interest to us, nutrient deprivation."The research team -- which also included Carnegie's Shai Saroussi, Weichao Huang, and Nicholas Akkawi -- investigated how the photosynthetic alga Chlamydomonas reinhardtii copes with a sparsity of nutrients. Their findings were recently published in The team revealed that polyphosphate synthesis is deeply integrated with cellular metabolism, leveraging this relationship to shape the alga's ability to adapt to challenges in its surroundings.Using advanced techniques, the researchers showed that the synthesis of polyphosphate is crucial for maintaining the optimal energy balance, enabling cellular physiological processes. When nutrient availability is low, polyphosphate synthesis is necessary for the alga to adjust its cellular metabolism and survive the adverse conditions. It does this by impacting the biochemical processes occurring in the cell's power centers -- mitochondria which perform respiration and chloroplasts which perform photosynthesis.If a cell's ability to synthesize polyphosphate is impaired, it is unable to accomplish normal electron transport in the mitochondria and chloroplasts -- central to the functions of these key organelles -- compromising cellular regulation, fitness, and survival."It is possible that the role of polyphosphate synthesis and mobilization in regulating the energetic functions of the cell under nutrient-limited conditions results in the creation of 'checkpoint' molecules within chloroplast and mitochondria that guide changes in the genes expressed in response to the environmental conditions," said lead author Sanz-Luque.This knowledge could potentially be harnessed to improve the resilience of other photosynthetic organisms and make them better able to survive the stress of a changing climate.Together Carnegie's Emanuel Sanz-Luque, Devaki Bhaya, and Arthur Grossman also published a comprehensive review in
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Climate
| 2,020 |
October 15, 2020
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https://www.sciencedaily.com/releases/2020/10/201015111729.htm
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Climate change likely drove early human species to extinction, modeling study suggests
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Of the six or more different species of early humans, all belonging to the genus Homo, only we Homo sapiens have managed to survive. Now, a study reported in the journal
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"Our findings show that despite technological innovations including the use of fire and refined stone tools, the formation of complex social networks, and -- in the case of Neanderthals -- even the production of glued spear points, fitted clothes, and a good amount of cultural and genetic exchange with Homo sapiens, past Homo species could not survive intense climate change," says Pasquale Raia of Università di Napoli Federico II in Napoli, Italy. "They tried hard; they made for the warmest places in reach as the climate got cold, but at the end of the day, that wasn't enough."To shed light on past extinctions of Homo species including H. habilis, H. ergaster, H. erectus, H. heidelbergensis, H. neanderthalensis, and H. sapiens, the researchers relied on a high-resolution past climate emulator, which provides temperature, rainfall, and other data over the last 5 million years. They also looked to an extensive fossil database spanning more than 2,750 archaeological records to model the evolution of Homo species' climatic niche over time. The goal was to understand the climate preferences of those early humans and how they reacted to changes in climate.Their studies offer robust evidence that three Homo species -- H. erectus, H. heidelbergensis, and H. neanderthalensis -- lost a significant portion of their climatic niche just before going extinct. They report that this reduction coincided with sharp, unfavorable changes in the global climate. In the case of Neanderthals, things were likely made even worse by competition with H. sapiens."We were surprised by the regularity of the effect of climate change," Raia says. "It was crystal clear, for the extinct species and for them only, that climatic conditions were just too extreme just before extinction and only in that particular moment."Raia notes that there is uncertainty in paleoclimatic reconstruction, the identification of fossil remains at the level of species, and the aging of fossil sites. But, he says, the main insights "hold true under all assumptions." The findings may serve as a kind of warning to humans today as we face unprecedented changes in the climate, Raia says."It is worrisome to discover that our ancestors, which were no less impressive in terms of mental power as compared to any other species on Earth, could not resist climate change," he said. "And we found that just when our own species is sawing the branch we're sitting on by causing climate change. I personally take this as a thunderous warning message. Climate change made Homo vulnerable and hapless in the past, and this may just be happening again."
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Climate
| 2,020 |
October 15, 2020
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https://www.sciencedaily.com/releases/2020/10/201015101801.htm
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Artificial cyanobacterial biofilm can sustain green ethylene production for over a month
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The great global challenges of our time, including climate change, energy security and scarcity of natural resources, promote a transition from the linear fossil-based economy to the sustainable bio-based circular economy. Taking this step requires further development of emerging technologies for production of renewable fuels and chemicals.
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Photosynthetic microorganisms, such as cyanobacteria and algae, show a great potential for satisfying our demand for renewable chemicals and reducing the global dependence on fossil fuels. These microorganisms have the ability to utilise solar energy in converting COEthylene is one of the most important organic commodity chemicals with an annual global demand of more than 150 million tons. It is the main building block in the production of plastics, fibres and other organic materials."In our research, we employed the genetically engineered cyanobacterium Synechocystis sp. PCC 6803 that expresses the ethylene-forming enzyme (EFE) acquired from the plant pathogen, Pseudomonas syringae. The presence of EFE in cyanobacterial cells enables them to produce ethylene using solar energy and COEthylene has a high energy density that makes it an attractive fuel source. Currently, ethylene is produced via steam cracking of fossil hydrocarbon feedstocks leading to a huge emission of CO"Although very promising results have been reported on ethylene-producing recombinant cyanobacteria, the overall efficiency of the available photoproduction systems is still very low for industrial applications. The ethylene productivity of engineered cyanobacteria is the most critical variable for reducing the costs and improving efficiency," says Postdoctoral Researcher Sindhujaa Vajravel.However, cyanobacteria have several limitations for efficient production, as they primarily accumulate biomass, not the desired products."They possess a giant photosynthetic light-harvesting antenna that leads to self-shading and limited light distribution in suspension cultures, which decreases productivity. The greatest limitation is that the production period of the cells is short, only a few days," explains Associate Professor Allahverdiyeva-Rinne.To solve these two problems, researchers entrapped ethylene-producing cyanobacterial cells within thin-layer alginate polymer matrix. This approach limits cell growth strongly, thus engaging efficient flux of photosynthetic metabolites for ethylene biosynthesis. It also improves light utilisation under low-light conditions and strongly promotes cell fitness. As a result, the artificial biofilms achieved sustainable photoproduction of ethylene for up to 40 days with a light-to-ethylene conversion efficiency that is 3.5 fold higher than in conventional suspension cultures.These findings open up new possibilities for the further development of efficient solid-state photosynthetic cell factories for ethylene production and scaling up the process to the industrial level.
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Climate
| 2,020 |
October 15, 2020
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https://www.sciencedaily.com/releases/2020/10/201015084517.htm
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Laser technology measures biomass in world's largest trees
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Laser technology has been used to measure the volume and biomass of giant Californian redwood trees for the first time, records a new study by UCL researchers.
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The technique, published in Professor Mat Disney (UCL Geography), lead author on the study, said: "Large trees are disproportionately important in terms of their above ground biomass (AGB) and carbon storage, as well as their wider impact on ecosystem structure. They are also very hard to measure and so tend to be underrepresented in measurements and models of AGB."We show the first detailed 3D terrestrial laser scanning (TLS) estimates of the volume and AGB of large coastal redwood trees (Sequoia sempervirens) from three sites in Northern California, representing some of the highest biomass ecosystems on Earth."The research contributes to an aspect of climate change research with increasing focus.Professor Disney add: "Big questions within climate science in response to rising COEstimating the size and mass of very large trees is an extremely difficult task. Previously, trees could only be weighed by cutting them down or by using other indirect methods such as remote sensing or scaling up from manual measurements of trunk diameter, both of which have potentially large margins of error.Working with colleagues at NASA, and with support from the NASA Carbon Monitoring System programme, the researchers used ground-based laser measurements to create detailed 3D maps of the redwoods. NASA's new space laser mission, GEDI, is mapping forest carbon from space, and the GEDI team are using Professor Disney's work to test and improve the models they use to do this.The trees scanned include the 88-metre tall Colonel Armstrong tree, with a diameter-at-breast height of 3.39 m, which they estimate weighs around 110 tons, the equivalent of almost 10 double-decker buses.The researchers compared the TLS estimates with other methods and found that their estimates correlated with those of 3D crown mapping, a technique pioneered by American botanist Stephen C. Sillett that involves expert climbers scaling giant redwoods to manually record fine details about their height and mass.Professor Disney's team found that their AGB estimates agreed to within 2% of the records from crown mapping. Crucially, they also found that both these 3D methods show that these large trees are more than 30% heavier than current estimates from more indirect methods.The researchers recommend that laser technology and 3D crown mapping could be used to provide complementary, independent 3D measures.Assistant Professor Laura Duncanson (NASA Earth Sciences & University of Maryland), last author on the study and member of the NASA GEDI science team, said: "Estimating the biomass of large trees is critical to quantifying their importance to the carbon cycle, particularly in Earth's most carbon rich forests. This exciting proof of concept study demonstrates the potential for using this new technology on giant trees -- our next step will be to extend this application to a global scale in the hopes of improving GEDI's biomass estimates in carbon dense forests around the world."
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Climate
| 2,020 |
October 15, 2020
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https://www.sciencedaily.com/releases/2020/10/201012120009.htm
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Fuels, not fire weather, control carbon emissions in boreal forest
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As climate warming stokes longer fire seasons and more severe fires in the North American boreal forest, being able to calculate how much carbon each fire burns grows more urgent. New research led by Northern Arizona University and published this week in
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The team surveyed the vast Western Boreal's diverse forest conditions by analyzing field data collected from 417 burn sites in six ecoregions in Canada and Alaska between 2004-2015. They found that the amount of carbon stored in soils was the biggest predictor of how much carbon would combust, and that soil moisture was also significant in predicting carbon release."In these northern forests, soil, not trees, can account for up to 90 percent of carbon emissions, so we expected that these organic soils would be a significant driver," said lead author Xanthe Walker of the Center for Ecosystem Science and Society at Northern Arizona University. "But we were surprised that fire weather and the time of year a fire starts proved to be poor indicators of carbon combustion. It's really about the fuels that are there when a fire starts."That's a pivotal finding, since fire weather, as measured by a Fire Weather Index, is one of the main tools scientists and fire managers currently use to model carbon emissions in these boreal forests. This study suggests fuels should be a bigger component of those models. "When we think of climate change and wildfires, we often instinctively think of extreme weather conditions," said Marc-André Parisien, a research scientist with the Canadian Forest Service and co-author of the study. "But our study shows that vegetation also matters -- a lot! Predicting future vegetation is a tough nut to crack, but this study emphasizes the need to keep chipping away at it."The vegetation patterns they uncovered were complex -- soil moisture, tree species composition, and stand age at the time of fire all interacted to predict combustion amounts. For instance, highly flammable black spruce was generally a predictor of carbon combustion, and the presence of this species increased with site moisture and stand age at the time of fire. But such interactions are likely to change with the climate. For example, as the climate warms and fire intervals shorten, black spruce stands are being replaced by deciduous trees and jack pine, which grow in shallower soils that release less carbon during fires. The site-level resolution of the study allowed the researchers to capture such dynamism in carbon combustion patterns, and offers clues about the way they may shift in the future."We really need to move beyond the misconception of the boreal forest as a monotonous stretch of forest," said Sander Veraverbeke, assistant professor at Vrije Universiteit Amsterdam and co-author of the study. "While only a few tree species occur in the boreal forest, its diversity in ecosystem structure, forest age, topography, peatland occurrence and permafrost conditions is enormous, and our paper shows that these features dictate the carbon emissions from boreal fires. The good news is that we can map aspects of this fine-scale ecosystem variation with current tools from NASA and other space agencies. Now we need to do this at the continental scale."The level of detail this study captured offers modelers a framework for asking more questions about carbon, said Michelle Mack, senior author on the study and professor of biology at Northern Arizona University. "In the past, fire models have focused on fire behavior, not carbon emissions," Mack said. "It's only been in the last decade or so that we've seen a global effort to quantify how much carbon these fires are releasing. We hope that our observations about fuels will inform the models as we work to better understand the boreal forest's emission trajectory."Parisien agreed. "We are figuring out that fire-vegetation feedbacks a lot stronger that we thought they were just a few years ago," he said. "Of course, we'll never be able to manage all of vast boreal biome -- nor should we want to -- but this helps us know what targeted actions, such as fire management or modifying forest vegetation, we can take to limit carbon loss."
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Climate
| 2,020 |
October 14, 2020
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https://www.sciencedaily.com/releases/2020/10/201014140940.htm
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Bringing people together on climate change
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A new study suggests that engaging, high-quality media programming could help Democrats and Republicans see eye to eye when it comes to climate change.
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The study, published in the Journal The researchers found that when Republicans and Democrats watched "Years of Living Dangerously," which aired in 2016 and won an Emmy Award, they were more likely to see eye to eye. Both were likely to believe that they could personally take action against climate change.Among Republicans who were most engaged with the "Years of Living Dangerously" program, their pre- and post-video surveys showed that their perceptions of the risks associated with climate change and their belief that they could take action were both greater after they watched the episode -- similar to those of Democrats."The more transported or absorbed an individual was by the documentary, the closer they paid attention. The more emotionally and cognitively involved they were, the more they felt climate change was a real risk affecting their lives," said Ashley Bieniek-Tobasco, research assistant professor of environmental and occupational health sciences at the University of Illinois Chicago School of Public Health and first author of the study."Those most engaged also tended to have stronger beliefs in their ability to take action to help tackle climate change, such as contacting a government official about climate change, after watching the videos," she said.Among the participants, 624 watched the videos in a lab setting and 1,391 watched the videos online.Of those who watched the videos in the lab, approximately 60% were Democrats, 9% were Republicans and 30% were other affiliations. Among participants who watched the videos online, approximately 37% were Democrats, 27% were Republicans and 37% were other affiliations.Survey questions before and after the videos focused on three main areas: perception of the risk posed by climate change, efficacy beliefs or beliefs that an individual can do something personally about climate change and narrative transportation."Narrative transportation is a term we use to describe how immersed or absorbed a person is while consuming a narrative, be it a film or a book," Bieniek-Tobasco said. "It encompasses attention and emotional and cognitive engagement with the story. It is the idea that you are transported into the story, or to another time or place while consuming the story.""Democrats started with higher-risk perceptions and efficacy beliefs in regard to climate change when compared to Republicans, but after watching the video, among participants who were most transported or engaged, that difference went away," she said.Bieniek-Tobasco and colleagues say their findings suggest that the messages used to persuade audiences can be very effective in influencing climate change attitudes and beliefs if the content is engaging."Narrative transportation predicts efficacy beliefs and risk perceptions and appears to reduce political polarization in climate change attitudes and beliefs," she said. "This tells us that engaging storytelling is potentially a powerful tool for combating polarization. If used in the right way, it may also catalyze changes in political behaviors needed to build political will to implement policy solutions to address climate change, and ultimately protect our health."This research, which was conducted by Bieniek-Tobasco under a research protocol at George Washington University, was funded in part by a grant from the Children's Investment Fund Foundation.
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Climate
| 2,020 |
October 14, 2020
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https://www.sciencedaily.com/releases/2020/10/201014140933.htm
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Recent Atlantic ocean warming unprecedented in nearly 3,000 years
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Taking advantage of unique properties of sediments from the bottom of Sawtooth Lake in the Canadian High Arctic, climate scientists have extended the record of Atlantic sea-surface temperature from about 100 to 2,900 years, and it shows that the warmest interval over this period has been the past 10 years.
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A team led by Francois Lapointe and Raymond Bradley in the Climate System Research Center of the University of Massachusetts Amherst and Pierre Francus at University of Québec-INRS analyzed "perfectly preserved" annual layers of sediment that accumulated in the lake on northern Ellesmere Island, Nunavut, which contain titanium left over from centuries of rock weathering. By measuring the titanium concentration in the different layers, scientists can estimate the relative temperature and atmospheric pressure over time.The newly extended record shows that the coldest temperatures were found between about 1400-1600 A.D., and the warmest interval occurred during just the past decade, the authors report. Francus adds, "Our unique data set constitutes the first reconstruction of Atlantic sea surface temperatures spanning the last 3,000 years and this will allow climatologists to better understand the mechanisms behind long-term changes in the behavior of the Atlantic Ocean."When temperatures are cool over the North Atlantic, a relatively low atmospheric pressure pattern is found over much of the Canadian High Arctic and Greenland. This is associated with slower snow melt in that region and higher titanium levels in the sediments. The opposite is true when the ocean is warmer -- atmospheric pressure is higher, snow melt is rapid and the concentration of titanium decreases.Lapointe says, "Using these strong links, it was possible to reconstruct how Atlantic sea surface temperatures have varied over the past 2,900 years, making it the longest record that is currently available." Details appear this week in The researchers report that their newly reconstructed record is significantly correlated with several other independent sediment records from the Atlantic Ocean ranging from north of Iceland to offshore Venezuela, confirming its reliability as a proxy for the long-term variability of ocean temperatures across a broad swath of the Atlantic. The record is also similar to European temperatures over the past 2,000 years, they point out.Fluctuations in sea surface temperatures, known as the Atlantic Multidecadal Oscillation (AMO), are also linked to other major climatic upheavals such as droughts in North America and the severity of hurricanes. However, because measurements of sea surface temperatures only go back a century or so, the exact length and variability of the AMO cycle has been poorly understood.Climate warming in the Arctic is now twice or three times faster than the rest of the planet because of greenhouse gas emissions from burning fossil fuels, warming can be amplified or dampened by natural climate variability, such as changes in the surface temperature of the North Atlantic, which appear to vary over cycles of about 60-80 years.Lapointe, who has carried out extensive fieldwork in the Canadian Arctic over the past decade, notes that "It has been common in recent summers for atmospheric high-pressure systems -- clear-sky conditions -- to prevail over the region. Maximum temperatures often reached 20 degrees Celsius, 68 degrees Fahrenheit, for many successive days or even weeks, as in 2019. This has had irreversible impacts on snow cover, glaciers and ice caps, and permafrost."Bradley adds that, "The surface waters of the Atlantic have been consistently warm since about 1995. We don't know if conditions will shift towards a cooler phase any time soon, which would give some relief for the accelerated Arctic warming. But if the Atlantic warming continues, atmospheric conditions favoring more severe melting of Canadian Arctic ice caps and the Greenland ice sheet can be expected in the coming decades."In 2019, Greenland Ice Sheet lost more than 500 billion tons of mass, a record, and this was associated with unprecedented, persistent high pressure atmospheric conditions."Lapointe notes, "Conditions like this are currently not properly captured by global climate models, underestimating the potential impacts of future warming in Arctic regions."
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Climate
| 2,020 |
October 14, 2020
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https://www.sciencedaily.com/releases/2020/10/201014114629.htm
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Plastic bags could be 'eco-friendlier' than paper and cotton
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Scientists from Nanyang Technological University, Singapore (NTU Singapore) have modelled the cradle-to-grave environmental impact of using different types of shopping bags and report that in cities like Singapore, single-use plastic bags (made from high-density polyethylene plastic) have a lower environmental footprint than single-use paper and multi-use cotton bags.
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Reusable plastic bags made from polypropylene non-woven plastic were the most eco-friendly option, followed by single-use plastic bags.The model revealed that cotton and kraft paper bags have relatively bigger environmental footprints due to their greater contribution to global warming and eco-toxicity potential in their production.However, the NTU team stressed that their model applied specifically to Singapore and might be applicable in cities such as Tokyo, Hong Kong, and Dubai. Reusable and single-use plastic bags would be a comparatively better environmental option only in these cities, due to the model's focus on densely populated metropolitan areas that have waste management structures with similar end-of-life incineration facilities.The findings were published in the scientific Assistant Professor Grzegorz Lisak, Director of Residues & Resource Reclamation Centre at the Nanyang Environment and Water Institute (NEWRI), who led the research, said: "Our main message is that re-usable plastic bags are the best option, provided that they are re-used many times -- over 50 times to be precise. However, one surprising conclusion is that, in our model, in a single-use case, plastic bags, if treated properly afterwards, are less environmentally detrimental than the other types of bags in this study.""It is essential to evaluate the implications case by case for dealing with plastic waste. In a well-structured closed metropolitan waste management system with incineration treatment, using plastic bags may be the best option that is currently available, provided that there is no significant leakage of waste into the environment."To reach their conclusions, the team carried out a life cycle analysis of five types of bags to evaluate the environmental impacts associated with their production, distribution, transportation, waste collection, treatment, and end-of-life disposal.The research team found that the global warming potential of a single-use kraft paper bag was the highest, over 80 times that of reusable plastic bags. Single-use plastic and reusable cotton bags (reused 50 times) were calculated to have over ten times the global warming potential of reusable plastic bags (reused 50 times).To offset the emission equivalent to equal that of the creation of one single-use plastic bag, a reusable plastic bag would need to be reused four times.The team also observed that the relative negative environmental impacts of cotton and kraft paper bags in the model are due to their production processes that consume immense amounts of water and natural resources. Hence, improving the production methods, optimizing resource usage, and following sustainable practices could in future favour the usage of bags made from cotton and paper.In the case of Singapore, the team recommends the usage of reusable plastic bags to the greatest extent possible to reduce consumption of single-use plastic bags. Reprocessing single-use plastic bags would be a good policy goal to cut down on their environmental impact.Asst Prof Lisak said that based on 2018 statistics in Singapore, reducing the single-use plastic grocery bag consumption by half could prevent over 10 million kg-CO2 equivalent emissions in a year.Moving forward, the team will be embarking on further studies connected to plastic waste management, waste plastic upgrading and the development of new products
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Climate
| 2,020 |
October 14, 2020
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https://www.sciencedaily.com/releases/2020/10/201014114619.htm
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Modern humans took detours on their way to Europe
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Favourable climatic conditions influenced the sequence of settlement movements of Homo sapiens in the Levant on their way from Africa to Europe. In a first step, modern humans settled along the coast of the Mediterranean Sea. Only then did they spread out into the Sinai desert and the eastern Jordanian Rift Valley. This is the result of archaeological research conducted by Collaborative Research Centre 'Our Way to Europe' (CRC 806) at the universities of Cologne, Bonn, and Aachen. The article 'Al-Ansab and the Dead Sea: mid-MIS 3 Archaeology and Environment of the Early Ahmarian Population of the Levantine Corridor' was published in
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For more than ten years, the team has been analysing sediments, pollen, and archaeological artefacts around the site of Al-Ansab 1 near the ancient ruin-city of Petra (Jordan). The goal was to gain an understanding of the environmental conditions that prevailed at the time of human expansion. 'Human presence consolidated in the region under favourable climate conditions', said Professor Dr Jürgen Richter, lead author of the study.The success story of anatomically modern humans outside of Africa began about 100,000 years ago with well-known sites such as Qafzeh and Skhul in Israel. However, these early records only reveal a brief, temporary expansion of the territory into the Levant. Permanent settlement of the region only dates back to about 43,000 years ago, scientists believe. During the epoch of the so-called 'Early Ahmarian', modern humans gradually had been spreading throughout the Levant -- a first step on their way to Asia and Europe.Favourable climatic conditions were preconditions for permanent human settlement. On a large scale, this is illustrated by the presence of the so-called Lake Lisan. This freshwater lake was located where the Dead Sea is today. However, it was of a much larger extent and carried greater water volume. Most of the water evaporated only with the end of the last ice age, leaving behind the hypersaline Dead Sea known today.Even on a small scale, the scientists were able to recognise the favourable environmental conditions: geo-archaeological teams from the University of Cologne and RWTH Aachen University examined the site of Al-Ansab 1. Whereas today, the Wadi Sabra, in which the site is located, is strongly shaped by seasonal flash floods, geomorphological and archaeological investigations showed that at the time of settlement, the conditions were less erosive and continuously wet, permitting the presence of humans.'This enabled the spread of humans from the coastal Mediterranean area to the formerly drier regions of the Negev desert and the eastern slopes of the Jordan Rift Valley. They hunted gazelles in the open landscape -- a prey we found in many sites in the region from this period', says Richter. 'Humans did not come by steady expansion out of Africa through the Levant and further to Europe and Asia. Rather, they first settled in a coastal strip along the Mediterranean Sea.'The region around the site of Al-Ansab 1 therefore was a stepping stone on Homo sapiens' way -- a journey that did not take a straight path to the European continent, but was guided by complex interactions between humans and their environment.
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October 14, 2020
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https://www.sciencedaily.com/releases/2020/10/201014082806.htm
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Biggest carbon dioxide drop: Real-time data show COVID-19's massive impact on global emissions
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While the ongoing coronavirus pandemic continues to threaten millions of lives around the world, the first half of 2020 saw an unprecedented decline in CO
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"What makes our study unique is the analysis of meticulously collected near-real-time data," explains lead author Zhu Liu from the Department of Earth System Science at Tsinghua University in Beijing. "By looking at the daily figures compiled by the Carbon Monitor research initiative we were able to get a much faster and more accurate overview, including timelines that show how emissions decreases have corresponded to lockdown measures in each country. In April, at the height of the first wave of Corona infections, when most major countries shut down their public life and parts of their economy, emissions even declined by 16.9 %. Overall, the various outbreaks resulted in emission drops that we normally see only on a short-term basis on holidays such as Christmas or the Chinese Spring Festival."The study, published in the latest issue of To paint this comprehensive and multidimensional picture, the researchers based their estimates on a wide array of data: precise, hourly datasets of electricity power production in 31 countries, daily vehicle traffic in more than 400 cities worldwide, daily global passenger flights, monthly production data for industry in 62 countries as well as fuel consumption data for building emissions in more than 200 countries.The researchers also found strong rebound effects. With the exception of a continuing decrease of emissions stemming from the transportation sector, by July 2020, as soon as lockdown measures were lifted, most economies resumed their usual levels of emitting COThus, the authors stress that the only valid strategy to stabilize the climate is a complete overhaul of the industry and commerce sector. "While the CO
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October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013164411.htm
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American Pikas show resiliency in the face of global warming
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The American pika is a charismatic, diminutive relative of rabbits that some researchers say is at high risk of extinction due to climate change. Pikas typically live in cool habitats, often in mountains, under rocks and boulders. Because pikas are sensitive to high temperatures, some researchers predict that, as the Earth's temperature rises, pikas will have to move ever higher elevations until they eventually run out of habitat and die out. Some scientists have claimed this cute little herbivore is the proverbial canary in the coal mine for climate change.
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A new extensive review by Arizona State University emeritus professor Andrew Smith, published in the October issue of the Smith has studied the American pika for more than 50 years and presents evidence from a thorough literature review showing that American pika populations are healthy across the full range of the species, which extends from British Columbia and Alberta, Canada, to northern New Mexico in the U.S.Occupancy in potential pika habitat in the major western North American mountains was found to be uniformly high. Among sites that have been surveyed recently, there was no discernible climate signal that discriminated between the many occupied and relatively few unoccupied sites."This is a sign of a robust species," Smith said.Smith said most of the studies that have raised alarms about the fate of the pika are based on a relatively small number of restricted sites at the margins of the pika's geographic range, primarily in the Great Basin. However, a recent comprehensive study of pikas evaluating 3,250 sites in the Great Basin found pikas living in over 73% of the suitable habitat investigated. Most important, the sites currently occupied by pikas and the sites where they are no longer found were characterized by similar climatic features."These results show that pikas are able to tolerate a broader set of habitat conditions than previously understood," Smith adds.Smith's most interesting finding is that pikas are apparently much more resilient than previously believed, allowing them to survive even at hot, low-elevation sites. Bodie California State Historic Park, the Mono Craters, Craters of the Moon National Monument and Preserve, Lava Beds National Monument, and the Columbia River Gorge (all hot, low-elevation sites) retain active pika populations, demonstrating the adaptive capacity and resilience of pikas. Pikas cope with warm temperatures by retreating into their cool, underground talus habitat during the hot daylight hours and augment their restricted daytime foraging with nocturnal activity.This doesn't mean that some pika populations have not been pushed to their limit, leading to their disappearance from some habitats. Smith's review points out that most documented cases of local loss of pika populations have occurred on small, isolated habitat patches."Due to the relatively poor ability of pikas to disperse between areas, those habitats are not likely to be recolonized, particularly in light of our warming climate," Smith said. "In spite of the general health of pikas across their range, these losses represent a one-way street, leading to a gradual loss of some pika populations. Fortunately for pikas, their preferred talus habitat in the major mountain cordilleras is larger and more contiguous, so the overall risk to this species is low."Smith's work emphasizes the importance of incorporating all aspects of a species' behavior and ecology when considering its conservation status, and that all available data must be considered before suggesting a species is going extinct. For the American pika, the data conclusively show that rather than facing extinction, American pikas are changing their behaviors in ways that help them better withstand climate change, at least for now.
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October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013134314.htm
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Without the North American monsoon, reining in wildfires gets harder
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The North American monsoon has dictated the length of wildfire season for centuries in the U.S.-Mexico border region, according to new University of Arizona research that can inform land management amid global climate change.
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But this year was anything but normal. The 2020 monsoon season was the second-driest on record, and many high-profile wildfires swept across the Sonoran Desert and surrounding sky islands. Putting an end to severe fires may only become harder as climate change makes monsoon storms less frequent and more extreme, say the authors of a new study published in the The U.S. may be able to learn from Mexico's wildfire management strategy, the researchers say."These large fire years are the result of many factors, but fire weather and seasonal climate loom very large in the picture. In the case of (Tucson's) Bighorn Fire (this summer), for example, we had a combination of unusually hot weather, low humidity and strong winds. When the monsoon is delayed, that means the fire season lasts longer, giving fires more time to burn," said study co-author Don Falk, professor in the School of Natural Resources and the Environment."It's well-known that what really gets us through May and June in Arizona is winter rainfall and snowpack. It adds moisture to the system," said lead study author Alexis Arizpe, who was a UArizona research specialist and graduate student in the Laboratory of Tree-Ring Research when he did the research. "The start of the fire season is controlled by winter rain, but the monsoon controls the end of it. The physical rainfall limits fire with deceased temperatures, increased humidity and soil moisture."Arizpe, who is now a technician at the Gregor Mendel Institute of Molecular Plant Biology in Vienna, Austria, and his colleagues analyzed patterns of widespread fire years going back more than 400 years using tree-ring samples extracted from sky island mountain ranges -- isolated mountaintops that are ecologically distinct from the surrounding valleys -- in southern Arizona and northern Mexico."Realistically, there's only one factor that could give you simultaneous large fires in multiple sky islands, and that's climate," Falk said. "We now understand that the sky island bioregion has a distinctive 'monsoon fire regime' different from anywhere else."Connie Woodhouse, a Regents Professor in the School of Geography, Development and Environment, and Tom Swetnam, Regents Professor Emeritus of Dendrochronology, were also co-authors on the study.Researchers have learned about the monsoon's role in regulating wildfires from records of past fires, but they didn't have the ability to assess it over long periods, Falk said. That recently changed when former Laboratory of Tree-Ring Research graduate student Daniel Griffin, now on the faculty at the University of Minnesota, compiled the first-ever tree-ring record that teased out monsoon rainfall from winter rainfall.When the team sorted out the interactions between winter and monsoon rainfall and wildfires, interesting relationships emerged."When it's wet in both seasons, you never get a big fire," Falk said. "When it's wet in winter and dry in the monsoon, you see fire occasionally. When it's dry in winter but a good monsoon, every now and then you get some big fires. But the real action is when it's dry in both seasons. Think of it as how much time fires have to burn."Also, heavy winter rainfall promotes fuel buildup. When a wet winter is followed by an especially dry year, there's a lot of built-up fuel, such as dry grass, that's primed for lightning strikes or stray sparks.Another pattern emerged in the data: Large, high-severity fires burn more often in the U.S. than in Mexico. This is mostly due to land management differences, Arizpe said. In many areas of Mexico, traditional land management practices continue. This includes seasonal grazing combined with local prescribed burning to renew grasslands, allowing low-severity fires to burn naturally as they have for centuries.In contrast, for the last 100 years, the U.S. Forest Service has focused heavily on fire suppression, meaning fires are snuffed out as soon as possible. As a result, fuels accumulate, providing fuel for more severe fires later, Falk said. Currently, nearly half of the U.S. Forest Service's budget funds fire suppression. As a result, the U.S. hadn't experienced many destructive wildfires until droughts of the 21st century produced unmitigated fuel for some of the largest wildfires the region has ever seen."Ironically, our investment is paying off in the form of gigantic fires that threaten our forests," Falk said.Using the tree-ring record, the team found that for centuries, low-intensity wildfires scarred but didn't kill trees about once every 10 years. This natural process is healthy for the regional ecosystem. Small fires that stay low to the ground clear up dead foliage on the forest floor and turn it into nutritious ash from which new plants can grow.Larger, more destructive fires cause public outcry that triggers a cycle that exacerbates the problem, Falk said. Fire suppression tactics allow fuels to accumulate. More fuel means more highly destructive fires and more public outcry. As a result, policy makers pour more money into suppression to protect human assets like towns and power lines.Such large, destructive fires do much more than scar trees. High severity fires can leave large landscapes with damaged soils and few living trees. It can take decades or even centuries for the ecosystem to recover, which can be detrimental to native species. In the meantime, erosions and landslides may occur.Climate change researchers predict that the region will only get hotter and drier as climate change progresses, resulting in more common and devastating wildfires, said Christopher Castro, associate professor of hydrology and atmospheric sciences, who was not involved with the research.Castro uses climate models to forecast future monsoons. His research shows that monsoon storms will become more intense but less frequent. This could also possibly delay the end of the wildfire season."This is all bad from a wildfire perspective," he said.Mexico, on the other hand, has let fires naturally run their course relative to the U.S. As a result, they have relatively more natural and less destructive wildfire patterns, although large fires have occurred there as well, Falk said."Looking forward, we have to accept the new reality that fire seasons will be longer and more severe in the future. This is simply the new world that we have created for ourselves and for nature by propelling climate change so rapidly," Falk said. "Managers will have a massive challenge on their hands dealing with this new reality, but certainly in the short run we need to provide them with the means to manage forests more proactively, including forest thinning, prescribed burning and other measures to reduce fuels."
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| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013134312.htm
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New global temperature data will inform study of climate impacts on health, agriculture
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A seemingly small one-to-two degree change in the global climate can dramatically alter weather-related hazards. Given that such a small change can result in such big impacts, it is important to have the most accurate information possible when studying the impact of climate change. This can be especially challenging in data sparse areas like Africa, where some of the most dangerous hazards are expected to emerge.
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A new data set published in the journal Data scientists Andrew Verdin and Kathryn Grace of the Minnesota Population Center at the University of Minnesota worked with colleagues at the Climate Hazards Center at the University of California Santa Barbara to produce and validate the data set."It's important to have this high-resolution because of the wide-ranging impacts -- to health, agriculture, infrastructure. People experiencing heat waves, crop failures, droughts -- that's all local," said Verdin, the lead author.By combining weather station data, remotely sensed infrared data and the weather simulation models, this new data set provides daily estimates of 2-meter maximum and minimum air temperatures for 1983-2016. Named CHIRTS-daily, this data provides high levels of accuracy, even in areas where on-site weather data collection is sparse. Current efforts are focused on updating the data set in near real time."We know that the next 20 years are going to bring more extreme heat waves that will put millions or even billions of people in harm's way. CHIRTS-daily will help us monitor, understand, and mitigate these rapidly emerging climate hazards," said Chris Funk, director of the Climate Hazards Center.Additionally, the people who are most vulnerable are often located in areas where publicly available weather station data are deteriorating or unreliable. Areas with rapidly expanding populations and exposures (e.g. Africa, Central America, and parts of Asia) can't rely on weather observations. By combining different sources of weather information, each contributes to provide detail and context for a more accurate, global temperature dataset."We're really excited about the possibilities for fine-scale, community-focused climate-health data analyses that this dataset can support. We're excited to see researchers use it," said co-author Kathryn Grace.
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Climate
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013134257.htm
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Port engineers need guidance incorporating sea level rise into construction designs
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A survey of maritime infrastructure engineers by University of Rhode Island researchers found that the rising sea level is often not factored into designs of ports, breakwaters, fishing piers and other coastal infrastructure.
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"If we're making decisions about infrastructure today and expect it to be serviceable for the next 50 to 75 years, we should be thinking about what the environmental conditions will be like towards the end of the infrastructure's life," said Austin Becker, URI associate professor of marine affairs, who studies how ports are preparing for climate change. "And we know that things are going to be very different along our coasts in the coming years."In 2019, Becker and graduate student Benjamin Sweeney surveyed 85 engineers at consulting firms, port authorities and government agencies with experience working on port infrastructure projects in the United States. They found that 64% do not have a policy or planning document to guide how to incorporate sea level change into their designs."The challenge they face is that they aren't receiving concrete, consistent guidance for what they should be doing to integrate sea level rise projections into their work," Becker said. "They need guidance, they want guidance, they don't want to have to go on the whims of their clients, who may not have expertise in this area. They also don't want to have to weigh potentially conflicting guidance from local, state or federal agencies."Becker said that without guidance, port engineers are more likely to disregard sea level change projections entirely."Formal policies or documents can lend credibility and provide the basis for recommendations," wrote Becker and Sweeney in a research paper in the Of the 29% of survey respondents that do have formal guidance from a sea level rise planning document, only 9% said they use it for all of their projects."That isn't surprising, but it's worrisome," said Becker, a visiting fellow at the U.S. Naval War College. "It's not surprising because of the times we live in; there's so much conflicting information out there about climate change. But scientists understand that sea levels are actually rising and that there will be ramifications, and it's going to make things much more expensive to not factor those changes into designs now."The survey also examined the factors that influenced whether engineers incorporate sea level rise into their designs. It found that 54% of respondents said they often or always factor in rising sea levels because it is required by their client, and 46% indicated they do so because it is a regulatory requirement.More than half of the respondents also said that "a lack of design standards" was the chief barrier to incorporating sea level rise into their infrastructure projects. Other answers included a lack of funding, the client doesn't want sea level rise incorporated, and concerns over the uncertainty of sea level rise projections."Regulatory standards and codes remove the burden on engineers to make subjective sea level rise decisions," Becker and Sweeney wrote. "This barrier also renders many of the other barriers less relevant."Based on the results of the survey, Becker and Sweeney recommend that engineers undertake a life cycle cost analysis that includes sea level rise projections for each project. This methodology can be used to support decision making for climate change adaptation alternatives.They also suggest that the engineering community collaborate with port authorities and regulatory bodies to create design standards to improve the resilience of port infrastructure."Engineers need something they can rely on so they can go to their clients and say, 'this is what we need to follow, and it's not optional,'" Becker said. "The guidance also has to be flexible enough so it can be adapted over time as conditions change, but it gives them something they can hang their hat on today."
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Climate
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013124129.htm
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Mental accounting is impacting sustainable behavior
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Mental accounting is a concept that describes the mental processes we employ to organise our resource use. Human beings tend to create separate mental budget compartments where specific acts of consumption and payments are linked. This mechanism can be counter-productive when it comes to energy consumption and can have a negative impact on attempts to reduce carbon emissions. Psychologists from the University of Geneva (UNIGE), working in collaboration with the University of Applied Sciences and Arts in Western Switzerland (HES-SO Valais), have published a perspective in the highly influential journal
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Mental accounting, a concept known by psychology researchers since the 1980s, describes how the human mind functions when performing acts of consumption. For instance, someone who has bought a cinema ticket in advance but who cannot find it on entering the cinema will typically not buy a second ticket: their film budget has already been spent! This example illustrates our tendency to mentally segment our budgets and link them to specific acts of consumption. "These basic cognitive mechanisms can help us better understand unsustainable behaviour. If they are taken into account, they could be used to fine-tune the way policy instruments are designed to fight climate change, improve prevention and promote sustainable behaviour," begins Tobias Brosch, professor in psychology of sustainable development at UNIGE's Faculty of Psychology and Educational Sciences and the Swiss Centre for Affective Sciences. "For this article, we used the currently ongoing discussions around the carbon tax to illustrate the impact of three mechanisms of mental accounting on behaviour and to propose ways to circumvent this impact."The spillover effect refers to the fact that we tend to justify one behaviour by another of our behaviours. "Someone who makes the effort to cycle to work every day will use this argument to justify, to himself or others, buying a plane ticket to go on holiday to the Seychelles. A possible intervention strategy to prevent this is to encourage people to create differentiated mental accounts using targeted messages," states the psychologist.The rebound effect explains how actions can induce a negative energy balance when people fail to adapt their budgets to a new situation. For example, people who buy an energy-efficient car may feel inclined to use it more often, cancelling out potential energy savings. To tackle this phenomenon, the psychologists suggest informing people about the real energy costs of their new car so they can update their consumption budget.Our minds create mental accounts with precise labels. The mental account that is opened when we receive a sum of money in a specific context determines what the money will be spent on. "A monetary gift received for a birthday will be labelled 'pleasure', and will most likely be spent on pleasurable experiences," says Professor Brosch by means of illustration. This can be problematic in the context of sustainable decision-making. For instance, the financial returns on solar panels installed at home appear only indirectly in the electricity bill and are not explicitly labelled as "energy saving." Accordingly, people will not necessarily think about reinvesting this money in new sustainable measures. "Clear labels are needed. In Switzerland, part of the carbon levy is returned to citizens via a reduction in health insurance costs. It would be better to label such an income 'Climate action revenue'," argues Tobias Brosch.The analysis carried out by the psychologists proposes concrete measures aimed at the political sphere so that pro-climate initiatives can be improved by factoring in human behaviour. "We need to clearly show the price of energy, make the message salient, and demonstrate the impact of consumption on COThe approaches developed in the perspective help conceptualise spending and diversify mental accounts so that individuals can better adapt their behaviours. But Hahnel warns: "Be careful to consider your values and not to fall into purely marketing-based initiatives. You cannot put sustainability labels on just any tax credit." "Bounded rationality, including mental accounting, can help introducing innovative policies for climate change mitigation in addition to price-oriented ones" adds Valentino Piana, senior economist at HES-SO, who contributed to the study. Professor Brosch concludes in the same tone: "Our work helps to understand behaviour, how humans make choices and take decisions. Our goal isn't to abolish free will, but to provide a behavioural toolbox. Policymakers can use this knowledge to develop strategies based not just on scientific evidence, but also on ethical considerations."
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Climate
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013105746.htm
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The deep sea is slowly warming
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New research reveals temperatures in the deep sea fluctuate more than scientists previously thought and a warming trend is now detectable at the bottom of the ocean.
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In a new study in AGU's journal They found all sites exhibited a warming trend of 0.02 to 0.04 degrees Celsius per decade between 2009 and 2019 -- a significant warming trend in the deep sea where temperature fluctuations are typically measured in thousandths of a degree. According to the study authors, this increase is consistent with warming trends in the shallow ocean associated with anthropogenic climate change, but more research is needed to understand what is driving rising temperatures in the deep ocean."In years past, everybody used to assume the deep ocean was quiescent. There was no motion. There were no changes," said Chris Meinen, an oceanographer at the NOAA Atlantic Oceanographic and Meteorological Laboratory and lead author of the new study. "But each time we go look we find that the ocean is more complex than we thought."Researchers today are monitoring the top 2,000 meters (6,560 feet) of the ocean more closely than ever before, in large part due to an international program called the Global Ocean Observing System. Devices called Argo floats that sink and rise in the upper ocean, bobbing along in ocean currents, provide a rich trove of continuous data on temperature and salinity.The deep sea, however, is notoriously difficult to access and expensive to study. Scientists typically take its temperature using ships that lower an instrument to the seafloor just once every ten years. This means scientists' understanding of the day-to-day changes in the bottom half of the ocean lag far behind their knowledge of the surface.Meinen is part of a team at NOAA carrying out a rare long-term study at the bottom of the ocean, but until recently, the team thought the four devices they had moored at the bottom of the Argentine Basin were just collecting information on ocean currents. Then Meinen saw a study by the University of Rhode Island showcasing a feature of the device he had been completely unaware of. A temperature sensor was built into the instrument's pressure sensor used to study currents and had been incidentally collecting temperature data for the entirety of their study. All they had to do was analyze the data they already had."So we went back and we calibrated all of our hourly data from these instruments and put together what is essentially a continuous 10-year-long hourly record of temperature one meter off the seafloor," Meinen said.The researchers found at the two shallower depths of 1,360 and 3,535 meters (4,460 feet and 11,600 feet), temperatures fluctuated roughly monthly by up to a degree Celsius. At depths below 4,500 meters (14,760 feet), temperature fluctuations were more minute, but changes followed an annual pattern, indicating seasons still have a measurable impact far below the ocean surface. The average temperature at all four locations went up over the course of the decade, but the increase of about 0.02 degrees Celsius per decade was only statistically significant at depths of over 4,500 meters.According to the authors, these results demonstrate that scientists need to take the temperature of the deep ocean at least once a year to account for these fluctuations and pick up on meaningful long-term trends. In the meantime, others around the world who have used the same moorings to study deep sea ocean currents could analyze their own data and compare the temperature trends of other ocean basins."There are a number of studies around the globe where this kind of data has been collected, but it's never been looked at," Meinen said. "I'm hoping that this is going to lead to a reanalysis of a number of these historical datasets to try and see what we can say about deep ocean temperature variability."A better understanding of temperature in the deep sea could have implications that reach beyond the ocean. Because the world's oceans absorb so much of the world's heat, learning about the ocean's temperature trends can help researchers better understand temperature fluctuations in the atmosphere as well."We're trying to build a better Global Ocean Observing System so that in the future, we're able to do better weather predictions," Meinen said. "At the moment we can't give really accurate seasonal forecasts, but hopefully as we get better predictive capabilities, we'll be able to say to farmers in the Midwest that it's going to be a wet spring and you may want to plant your crops accordingly."
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Climate
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013101632.htm
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Act now on wildfires, global climate change, human health, study says
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Immediate actions are needed to limit the greenhouse gas emissions that are driving climate change that helps fuel wildfires, a Monash University study says.
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A special report published in the The report, which analysed numerous studies on wildfires over the past 20 years, says global climate change is fueling the three essential conditions for wildfires -- fuel, oxygen and an ignition source. The world is seeing inconsistent rainfall, increased drought and hotter temperatures, leading to more flammable vegetation.It says the global mean carbon dioxide (COThe report says projections suggest that if high greenhouse gas emissions continue, wildfire exposure could substantially increase to over 74 per cent of the global land mass by the end of the century.However, if immediate climate mitigation efforts are taken to limit the global mean temperature increase to 2.0?C or 1.5?C, a corresponding 60 per cent and 80 per cent, respective increase in wildfire exposure could be avoided, the report says.Reaching the 1.5°C target would require reducing global net COThe report says the devastating health impacts are illustrated by several large and -- in some cases -- unprecedented recent wildfires. These include the 2019-2020 Australian wildfires, the 2019 and 2020 Amazon fires in Brazil, the 2018 and 2020 wildfires in the western US, the 2017-2018 wildfires in British Columbia, Canada, and the ongoing record-breaking wildfires on the US West Coast.Along with the increased eye irritation, corneal abrasions and respiratory impacts of the smoke, the psychological effects are equally as serious with post-traumatic stress disorder (PTSD), depression, and insomnia common. The psychological consequences of wildfire events can persist for years, with children and adolescents particularly vulnerable.A 20-year study on adults exposed to an Australian bushfire disaster as children in 1983 found an increase in psychiatric morbidity in adulthood, with wildfire events associated with subsequent reductions in children's academic performance.The report says the current exchange between wildfires and climate change is likely to form a reinforcing feedback loop, making wildfires and their health consequences increasingly severe, unless we can come together to reduce greenhouse gas emissions.
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Climate
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013124158.htm
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Atmospheric dust levels are rising in the Great Plains
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Got any spaces left on that 2020 bingo card? Pencil in "another Dust Bowl in the Great Plains." A study from University of Utah researchers and their colleagues finds that atmospheric dust levels are rising across the Great Plains at a rate of up to 5% per year.
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The trend of rising dust parallels expansion of cropland and seasonal crop cycles, suggesting that farming practices are exposing more soil to wind erosion. And if the Great Plains becomes drier, a possibility under climate change scenarios, then all the pieces are in place for a repeat of the Dust Bowl that devastated the Midwest in the 1930s."We can't make changes to the earth surface without some kind of consequence just as we can't burn fossil fuels without consequences," says Andy Lambert, lead author of the study and a recent U graduate. "So while the agriculture industry is absolutely important, we need to think more carefully about where and how we plant."The research is published in In the 1930s, a drought blanketed the Great Plains, from Mexico to Canada. This wouldn't have been such a big deal except that in the 1920s Midwestern farmers had converted vast tracts of grassland into farmland using mechanical plows. When the crops failed in the drought the open areas of land that used to be covered by grass, which held soil tightly in place, were now bare dirt, vulnerable to wind erosion."The result was massive dust storms that we associate with the Dust Bowl," Lambert says. "These dust storms removed nutrients from the soil, making it more difficult for crops to grow and more likely for wind erosion to occur." After years of drought, dust and hardship, rain finally began to fall again, bringing the Dust Bowl to a close."But the damage was already done to the soil," Lambert says. "Some areas have still not fully recovered."Around the 2000s, the growth in demand for biofuels spurred renewed expansion of farmland to produce the needed crops. In an echo of the 1920s, this expansion replaced stable grasslands with vulnerable soil. Over five years, from 2006 to 2011, 2046 square miles (530,000 hectares) of grassland in five Midwestern states became farmland -- an area a little smaller than Delaware.At the same time, parts of the Great Plains experienced longer and more severe droughts in the 20th century. The future of drought in that region is, so far, uncertain, but the potential for a warmer, drier Great Plains has Lambert and co-author Gannet Hallar, associate professor of atmospheric sciences, bringing up the word "desertification" in relation to the potential future of the region.The focus of the study by Lambert, Hallar and colleagues from the U, the University of Colorado-Boulder and Colorado State University, was to quantify how much the amount of dust in the atmosphere over the Great Plains had changed in recent decades. To do that, they tapped into instrumentation that measures atmospheric haziness from the ground up and from space down. From the ground, the IMPROVE monitoring network is run by several federal agencies and measures the amount of particulate matter in the air at sites, including national parks, around the country. Another ground-based network, the NASA-run AERONET, watches for how much incoming sunlight is blocked by dust and aerosol particles in the air. From space, an instrument called MODIS does the same job, looking at how much light reflected from the surface is similarly blocked by particles.All together, the data cover years from 1988 to 2018. Dust, they found, is increasing in the atmosphere over the whole of the Great Plains by as much as 5% per year."The amount of increase is really the story here," Hallar says. "That 5% a year over two decades, of course, is a hundred percent increase in dust loading. This is not a small signal to find."The researchers further found correlations between dust in the atmosphere and crop timings. In Iowa, where soybeans have been a major expanding crop, increases in dust appeared in June and October -- planting and harvesting months, respectively, for soybeans. In the southern Great Plains states, where corn is a more dominant crop, dust increases appeared in March and October -- again correlating to corn planting and harvesting seasons.That was remarkable," Hallar says, "in the sense of how clear the signal was.""I think it's fair to say that what's happening with dust trends in the Midwest and the Great Plains is an indicator that the threat is real if crop land expansion continues to occur at this rate and drought risk does increase because of climate change," Lambert says. "Those would be the ingredients for another Dust Bowl.""This is an example of the need for the agricultural community in the U.S. to think about adapting and mitigating to a changing climate," Hallar says. "So if we become more arid we will need to think about the impacts of land degradation in that changed climate. What we did in the past isn't necessarily what we can do in the future."
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Climate
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October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013105813.htm
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Unique view into the new Arctic
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With the return of the Polarstern, the largest Arctic expedition of all times has come to a successful end. For more than a year, the German research icebreaker travelled in 5 cruise legs with more than 400 people from 20 countries to investigate the epicentre of climate change more precisely than ever before. At the end of the expedition, which cost around 140 million euros, the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), came to a positive conclusion: despite all the unforeseeable difficulties, it had succeeded in advancing knowledge about the Earth's climate system and its changes by a decisive step.
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From Leipzig's point of view, the complex project was also successful: all 7 participants from the Leibniz Institute for Tropospheric Research (TROPOS) and the Leipzig University are back in good health and with valuable climate data. Two measurement programmes that are central to research into the Arctic atmosphere were able to be carried out in full despite weather extremes and corona: A multi-wavelength lidar scanned the air layers above Polarstern during the entire expedition. In 369 days, 640 million laser pulses went into the sky and 112 gigabytes of data were collected. In July, the MOSAiC atmosphere team was able to measure the lowest air layer above the melting ice floe with a captive balloon. Within a tight time window, 33 balloon ascents were achieved, during which a total of 31725 metres of rope were unwound and rewound. The balloon measurements by TROPOS and Leipzig University are particularly important for understanding the polar atmosphere during the melting phase, because the measurements originally planned in parallel with aircraft from Spitsbergen had to be postponed until autumn due to the corona pandemic."We are pleased that the ambitious plans have essentially been realised despite all the difficulties. A highlight are definitely the insights into the troposphere at the North Pole during the winter with our lidar. Nobody has ever been able to observe it so far north during the polar night off MOSAiC," says Prof. Andreas Macke, Director of TROPOS. The evaluation of the data is still in full swing, but there are indications that the same applies to the atmosphere as to the ice on the ground: "There are many indications that the atmosphere of the Arctic has already changed significantly. We have seen more smoke than expected. The huge forest fires are apparently affecting the polar regions. Even these once pristine areas seem to have reached the 'Pyrocene'. However, it will take months before concrete results are available, during which the data will have to be examined, analysed and discussed before they can finally be published. "The fact that we have measured both the atmosphere and the energy balance on the ground over a complete Arctic year will contribute greatly to our understanding of Arctic warming," adds Macke.At the moment, the joy that people and technology have survived the strains well outweighs. Also at Dr. Ronny Engelmann, scientist and laser expert from TROPOS, who is responsible for the remote sensing measurements within the OCEANET project on Polarstern: "It was fascinating to experience the Arctic in winter and to be allowed to be in a region where only a few people have been before at this time of year. As a scientist, I am glad that, thanks to good care by my colleagues, our equipment has been able to last for a year and has also survived the extreme cold of the polar night with temperatures down to -40 degrees Celsius without any failures. The experiences of the last ten years, during which our OCEANET container has been on board of Polarstern, have been a great help. Without stable technology, we would never have known what dust layers had moved across the Arctic," physicist Engelmann looks back. The lidar was in operation from 28 September 2019 to 02 October 2020 without any significant failures. This was ensured by Dr Ronny Engelmann, Hannes Griesche, Martin Radenz, Julian Hofer and Dr Dietrich Althausen, some of whom spent up to four months on the five sections of the cruise. Even though the remote sensing instruments run mostly automatically, they need regular maintenance: the flash lamps that emit the laser pulses had to be changed five times, for example, or 60 litres of liquid nitrogen had to be replaced each time the microwave radiometer was calibrated. Together with other instruments such as radiation meters, cloud camera, rain gauge and photometer on the OCEANET measuring container from TROPOS, a total of over one and a half terabytes of data were collected and around 60,000 kWh of electricity was consumed.While the remote sensing instruments on the foredeck of Polarstern could practically run the entire expedition, the teams on the ice had only a short time window each, which had to be used as effectively as possible. The balloon team from TROPOS and Leipzig University was able to work on the ice for a total of 37 days. Thanks to support from other teams, 33 balloon ascents were achieved, in which the BELUGA tethered balloon, which was the size of a bus, could measure aerosol particles, radiation and meteorological parameters up to a height of 1500 metres above the ice. To fill the balloon several times, 474 cubic metres of helium were consumed and holes up to 6 metres deep had to be drilled into the thawing ice for the ice anchors. "Our time on the ice was short but intense. The many melt ponds and frequent polar bear visits demanded a lot of improvisation. Because of the support from the whole MOSAiC team we were able to master difficult situations. This made our balloon measurements a big team effort from a great team that I will remember for a long time to come," said Christian Pilz of TROPOS. The vertical profiles that Pilz recorded together with the radiation measurements of his colleague Michael Lonardi from Leipzig University will provide important insights into the lower atmosphere of the summer Arctic. For example, the team was able to register temperatures of 14 degrees Celsius at an altitude of 300 metres, although the temperature on the ground was only just above freezing point. Without such on-site measurements, it would not be possible to estimate the influence of the air layers on the ground on thawing sea ice.Originally it was planned to study the near-ground atmosphere above the MOSAiC ice floe by tethered balloon and the higher layers by aeroplane in early summer. However, due to the corona pandemic, flights via Spitsbergen were not possible at that time. Supply and personnel exchange had to be organised with research vessels from Germany and the aircraft campaign had to be postponed until September. "The measurements with the Leipzig tethered balloon are therefore important in-situ aerosol measurements at MOSAiC in this layer of air, which is very important for the climate in the Arctic," emphasises Andreas Macke from TROPOS, "As an atmospheric researcher, I am particularly pleased that the balloon experiment was successful for the second time after 2017 and provided very valuable data."In September 2020, the German research aircraft Polar 5 and Polar 6 of the AWI were the first foreign aircraft to take off from the airport Longyearbyen for several measurement flights from Spitsbergen to the central Arctic to study the atmosphere in the context of MOSAiC since the corona lockdown: "With the extensive measurements on radiation and particles, we want to find out how clouds in the Arctic affect warming on the ground. In recent years, the Arctic has warmed up more than any other region on earth. The feedback mechanisms involved are very complex and not yet sufficiently understood. This knowledge is essential, however, if climate models are to be able to estimate how quickly the climate there will change, even for the region around the North Pole," explains Prof. Manfred Wendisch from the Leipzig University, who is also the spokesman for the Collaborative Research Centre "Arctic Climate Change" of the German Research Foundation (DFG). The network includes the universities in Bremen, Cologne and Leipzig as well as the AWI in Bremerhaven and the TROPOS in Leipzig. The aim of the research network is to observe the dramatic climate change in the Arctic using various methods in order to improve the reliability of models and enable more accurate predictions of further warming in the Arctic. The MOSAiC expedition will make a significant contribution to this and will be intensively evaluated by the alliance partners in the coming months."I'm very pleased with how the MOSAiC expedition progressed, and what a complete success it has been. Through the expedition, we can provide the climate data and observations that humanity so urgently needs in order to make fundamental and pressing political decisions on climate protection," said Prof Markus Rex, Expedition Leader and head of the MOSAiC project, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). "We've seen how the Arctic ice is dying. In the summer, even at the North Pole, it was characterised by extensive melting and erosion. If we don't make immediate and sweeping efforts to combat climate warming, we'll soon see ice-free Arctic summers, which will have incalculable repercussions for our own weather and climate. Though today the Central Arctic remains a fascinating, frozen landscape in winter, the ice is only half as thick as it was 40 years ago, and the winter temperatures we encountered were nearly always ten degrees warmer than what Fridtjof Nansen experienced on his ground-breaking Arctic expedition over 125 years ago."On 20 September 2019 Polarstern departed from the Norwegian port of Tromsø, bound for the Central Arctic, the epicentre of climate change. Once there, the ship allowed itself to become trapped in the ice, and began a one-year-long drift across the North Pole, completely at the mercy of natural forces -- the route and speed were solely determined by the ice drift, powered by wind and currents. Over the five cruise legs of the expedition, a total of 442 researchers, Polarstern crewmembers, young investigators, teachers and members of the press took part. Seven ships, several aircraft and more than 80 institutions from 20 countries were involved. The researchers, who hailed from 37 countries, had a common goal: to investigate complex interactions in the climate system between the atmosphere, ice and ocean, so as to better represent them in climate models. They also explored life in the Central Arctic for an entire year. Now they have returned home with a wealth of impressions from the rapidly transforming Arctic, and with an unparalleled treasure trove of data, which an entire generation of climate researchers will focus on analysing.From Leipzig's perspective, the next major measurement campaign in the Arctic will be the "HALO (AC)" mission with the German research aircraft HALO and Polar 6 in spring 2022. The tethered balloon BELUGA, on the other hand, will already return to the Arctic skies in late summer 2021 -- if pandemic conditions permit.
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Climate
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013105811.htm
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Darwin's theory about coral reef atolls is fatally flawed
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Marine geologist and oceanographer André Droxler knows Charles Darwin's theory about atolls is incorrect. But Droxler, who's studied coral reefs for more than 40 years, understands why Darwin's model persists in textbooks, university lecture halls, natural science museums and Wikipedia entries.
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"It's so beautiful, so simple and pleasing that everybody still teaches it," said Droxler, who recently retired from Rice University. "Every introductory book you can find in Earth science and marine science still has Darwin's model. If they teach one thing about reefs or carbonates in marine science 101, they teach that model."Droxler, a professor of Earth, environmental and planetary sciences at Rice for 33 years, is hoping to set the record straight with a 37-page, tour de force paper about the origins of atolls. Published this month in the Darwin's theory about the formation of atolls was published in 1842, six years after his legendary voyage aboard the British survey ship HMS Beagle. A geologist by training, Darwin was keenly interested in the rocks and landforms he encountered in his five years aboard the Beagle. The ship's primary mission was surveying coastlines and hazards to navigation, and the ship's orders included collecting detailed observations of the tides and ocean depths around a coral atoll."They spent a lot of time mapping reefs because they were such hazards to shipping," Droxler said of the Royal Navy. Atolls were particularly interesting and dangerous. Some were topped with low-lying islands but many were jagged rings of coral-topped rock that sat just below the water's surface, ready to rip the bottom out of unwary passing ships. "They come out of the abyssal plain of the ocean to almost no depth," Droxler said. "So they needed to know exactly where they were located."The Beagle, like every Royal Navy vessel, carried charts with the marked location of every known reef, and Darwin put these to use in his 1842 paper."He published a beautiful map that compiled all the known reefs on Earth," Droxler said. "It's amazing, when you compare satellite images of reefs today versus his map. It's almost the same. It's unbelievably accurate."But unlike navy maps that simply marked reefs as hazards to navigation, Darwin systematically classified each into one of three categories. Those attached to land, he called fringing reefs. Those detached from land and separated by a lagoon were barrier reefs. The third category was atolls, ring reefs that enclosed a central lagoon but no land.At the time, geologists believed continents were steadily rising out of the Earth and oceans were steadily sinking. Darwin noticed that both fringing and barrier reefs tended to surround volcanic islands, and he reasoned reefs initially formed on the fringe of volcanic islands. When the volcano died and slowly sank back into the ocean, the reef remained, first becoming a separated barrier reef and eventually, after the volcano sank entirely, an atoll.Droxler said he's awed by Darwin's ability to synthesize all that was known about reefs in his day and come up with such a simple, comprehensive and compelling theoretical model. But beauty aside, Darwin could not have accurately predicted how atolls form because he lacked the key piece of information, Droxler said."Cyclic changes in sea level drive atoll formation," Droxler said. "Darwin had no concept that sea level could go up and down, because glaciation didn't become common knowledge until the 1860s."Droxler said the simplicity of Darwin's classification system and theory could play a role in its continued appeal. A more accurate description of atoll formation has been around since the 1930s, but it is considerably more complicated and much of the evidence to support it is more recent, coming in the past 40 years from dozens of scientific and oil industry drilling expeditions as well as from the compiled record of Earth's climate and sea level history.Today's atolls formed in the past 500,000 years, Droxler said, driven by five wild swings in sea level that occurred every 100,000 years. In each cycle, sea level rose and fell by 120 meters or more. But to fully appreciate how changing sea level created atolls, it helps to start much earlier, Droxler said."The Earth's climate has changed quite dramatically in the last 5 million years," he said. "From about 5 million years ago to 2.5 million years ago, we had a rather warm climate that did not change very much, and sea level remained relatively constant. At that time, the Earth was producing flat-topped banks where today we have atolls."Sea level rose steadily but slowly, and the flat-topped banks that would give birth to atolls were created by countless generations of corals and other sea creatures that lived and died, adding their skeletons to the mineralized floor of the shallow, flat-topped marine ecosystem. The flat-top banks grew steadily, keeping pace with sea level until the warm period ended about 2.5 million years ago."The climate began to fluctuate into cycles," Droxler said. "There were alternate periods of warm and cold, but overall, the trend was that the Earth's climate got colder and colder and colder, interrupted by short warm swings."Throughout this period, ice caps were thickening. As ice accumulated, sea level fell, exposing the tops of the flat carbonate banks, which rose out of the ocean like bleached stone mesas. When rain fell atop the exposed banks, it slowly dissolved the carbonate, and standing water sped up the process. Puddles and ponds gradually carved bowl-like depressions. And over 2 million years, this process turned white mesas into ring-like towers with hollowed-out central depressions."Ice volume on Earth reached its initial maximum around 500,000-600,000 years ago, when a mile of ice covered Chicago, and New York was at the southern edge of a massive ice sheet on North America, comparable to modern Antarctica," Droxler said "There was so much ice in North America, Scotland, Scandinavia and Siberia that sea level was reaching 120 meters to 130 meters below what it is today."The five dramatic swings in sea level that occurred in the past half-million years were driven by Earth's ability to form large northern ice sheets, and by the sensitivity of those ice sheets to slight climatic changes, like fluctuations in the amount of sunlight landing in the far Northern Hemisphere due to slight changes in the planet's orbit and tilt."Because these big ice sheets formed in North America, not on the pole, but centered in relatively low latitude about 65 degrees north, they accumulated huge ice volumes that lowered sea level by more than 120 meters," he said. "But also, they were able to melt very quickly. And so we observe, now, these cyclic high-amplitude swings of sea level. And the first big swing was about at 450,000 years ago, when it went from minus-135 meters to plus-10 meters of what we have today."During each swing, the hollowed out flat-topped banks were resubmerged during warm periods, when sea level rose near its highest level. During those periods, as today, coral recolonized the highest parts of the eroded banks, in particular along their raised outer rims."Now you're adding carbonate on to their raised rim, and you're creating the modern atolls," Droxler said. "But this period of high sea level doesn't last for more than 10,000-12,000 years, and it goes down again. So now you are adding some reef on the rim, but then dissolving the lagoon again when sea level retreats. So you are enhancing the morphology even more with each cycle now, growing on the margin and dissolving in the middle."Droxler's and Jorry's in-depth study contains dozens of illustrations, including some comparisons of Darwin's original drawings with contemporary maps and satellite imagery. And the paper draws on decades of marine geological data compiled from dozens of expeditions, including recent datasets acquired by both co-authors in the Indian Ocean. Droxler said he and Jorry had discussed such a paper for years, but it might not have happened without the 2020 pandemic.Droxler moved to a remote ranch in Central Texas after retiring, and when the pandemic shut down travel in March, he was faced with the prospect of being there for some time."For years, Stéphan had pushed me, saying we should publish this, but you know, you always kind of do something else and something else," Droxler said. "At the end of March, Stéphan called me and said, 'I'm stuck in France, at home, and you're stuck in the middle of the countryside in Mason County. Let's write this paper.' And so that's what we did."
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Climate
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October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013105801.htm
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Rainforest model offers glimpse into future of the Amazon
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Tropical forests may be more resilient to predicted temperature increases under global climate change than previously thought, a study published in the journal
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The group studied data from the rainforest habitat at UArizona's Biosphere 2 and compared them to measurements taken at natural tropical forest sites. Due to being encased under a glass dome, the tropical forest at Biosphere 2 is possibly the hottest tropical forest in the world, with temperatures reaching up to 40 degrees Celsius, about 6 C higher than maximum temperatures currently experienced by natural tropical forests and in the range of what scientists expect them to experience in the year 2100, absent major climate change mitigation.At Biosphere 2, when the effects of warming and drying were separated, the authors observed that, just as in natural forests, photosynthesis declined as the air dried, but when the air was wet, the trees continued to photosynthesize steadily at ever higher temperatures, right up to a forest-roasting 38 C."No previous studies of tropical forests looked at changes in temperature much beyond to what they experience today," said Scott Saleska, a professor in the UArizona Department of Ecology and Evolutionary Biology and senior author of the paper. "Biosphere 2 gave us a unique opportunity to look at what might happen when these forests get the full global warming treatment."The paper's lead author, Marielle Smith -- a postdoctoral research associate at Michigan State University who pursued the research while she was a doctoral student in Saleska's lab at UArizona -- noted that "previous studies suggest that tropical forests are already approaching the limit of what they can tolerate in terms of temperature, provoking concern about the impacts of future warming.""But when we looked at the rainforest in Biosphere 2, we saw that, under some conditions, the trees there were functioning well beyond temperatures currently deemed to be the limit, and even higher than those predicted for the Amazon basin by 2100," she said.Smith and her co-authors wanted to know why. Biologists have long known that plants' ability to actively conduct photosynthesis, or turn carbon dioxide and water into biomolecules using sunlight, declines above a certain temperature threshold. However, the reason for this limit is not always clear.That is because as temperature increases, the relative humidity goes down, and photosynthesis can decline due to the temperature increase, the decline in water content or both. Similar to an assembly line in a factory, where productivity could be affected by a shortage of supplies entering the production process or by an excessively hot working environment directly impacting the physical performance of workers, the productivity of forests could be limited by a shortage of raw materials -- in this case, atmospheric water vapor, or humidity -- or by high temperatures wreaking havoc with the biochemical machinery itself.Understanding the reason for photosynthetic decline at higher temperatures is important because while the latter mechanism -- direct susceptibility to temperature -- would imply that tropical forests are highly vulnerable to future warming trends, the former would indicate some degree of resilience, especially under future elevated levels of carbon dioxide.The problem is that in the natural world, higher temperatures and lower water content almost always go hand-in-hand, so their effects cannot easily be separated. In Biosphere 2, however, the climate can be adjusted in ways not possible in the natural world."The enclosed environment at Biosphere 2 allowed us to maintain high humidity despite high temperatures by adding water vapor via misters and trapping humidity inside the glass enclosure, which is something that would not happen in a natural tropical forest," Smith explained.This finding can be understood in terms of basic plant behavior: When there is less moisture in the air, plants react by limiting the opening of their stomata -- microscopically small openings in their leaves -- to take in carbon dioxide, one of the raw materials for synthesis. The longer the stomata remain open, the more carbon dioxide can enter the leaf, but that comes at a price: The drier the air surrounding the plant, the more water escapes through the openings, forcing the plant to strike a balance between carbon uptake and water loss.The reduction in photosynthetic productivity that previous studies had observed in the face of warmer temperatures, therefore, is likely due to plants limiting the time they keep their stomata open when confronted with drier air, in an effort to preserve water. This, in turn, limits how much carbon dioxide can enter the leaf, which may be behind the drop in photosynthetic productivity rather than the alternative scenario, in which heat damages the photosynthetic apparatus directly.To assess the sensitivity of tropical forests to future warming, the authors compared the response of photosynthesis to high temperatures in the Biosphere 2 tropical forest to that of natural tropical forest sites in Mexico and in the Brazilian Amazon. So-called eddy flux towers reaching up to nearly 200 feet high, taller than the forest canopy, allow researchers to measure the exchange of carbon dioxide between the forests and the atmosphere."Flux towers allow us to measure the exchange of carbon dioxide between the forests and the atmosphere that we used to calculate total forest photosynthesis," Smith said. "When we looked very closely at the flux tower data, we could tell that it was the same mechanism that was causing declines in real-world photosynthesis during warm periods as in Biosphere 2; it was the decline in water vapor, not the increase in temperature.""We interpret these findings such that in the presence of high humidity, the stomata in the leaves can remain open longer without losing as much water," said Tyeen Taylor, a co-author of the paper and postdoctoral research associate at the University of Michigan.The authors discuss how heightened carbon dioxide in the atmosphere has the potential to have the same effect, because when more carbon dioxide is available, plants can keep their stomata opening times shorter, too, thereby limiting their water loss.The authors point out that while their findings suggest that tropical forests may be more resilient to future warming than previously thought, that does not mean that tropical forests are not vulnerable to future climate change, as photosynthesis is not the only aspect of forest health."For example, reproduction could be affected independently, growth could be affected independently, herbivore and pathogen susceptibility could increase," Smith said. "There are many other reasons not to say, 'tropical forests are out of the woods.'"The authors pointed out that Amazon forests are facing great threats from fires, deforestation and habitat destruction, and while the study may point to some resilience to coping with a warming world, "that hardly means these forests are safe, any more than slowing down as you run a red light is safe," Saleska said."We are already headed deep into the tropical forest danger zone, and if we don't mend our ways, in terms of reducing both fossil fuel emission and especially large-scale fires and increased deforestation rates, the fate of these forests will be grim indeed," he said. "What this study implies, instead, is the good news that we may still have a chance, if we act now, to save these valuable tropical forests."
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Climate
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October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013101635.htm
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The effects of repeated droughts on different kinds of forests
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Drought is endemic to the American West along with heatwaves and intense wildfires. But scientists are only beginning to understand how the effects of multiple droughts can compound to affect forests differently than a single drought alone.
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UC Santa Barbara forest ecologist Anna Trugman -- along with her colleagues at the University of Utah, Stanford University and the U.S. Forest Service -- investigated the effects of repeated, extreme droughts on various types of forests across the globe. They found that a variety of factors can increase and decrease a forest's resilience to subsequent droughts. However, the study, published in Droughts usually leave individual trees more vulnerable to subsequent droughts. "Compounding extreme events can be really stressful on forests and trees," said Trugman, an assistant professor in the Department of Geography. She compares the experience to a person battling an illness: You'll be harder hit if you get sick again while you're still recovering.That said, the case is not quite so clear cut. "Theoretically, responses to subsequent droughts could be quite varied depending on a wide range of tree-level and ecosystem-level factors," said lead author William Anderegg, an assistant professor at the University of Utah. So, while a drought may place a tree under considerable stress, it could also kill off some of its neighbors, leaving the survivors with less competition for water should arid conditions return.Trugman and her colleagues used a variety of data sources to investigate this effect on a broad scale. Tree ring data spanning over 100 years enabled them to see how trees that survived an initial drought grew afterward. Data from the U.S. Forest Inventory and Analysis gave them access to metrics on tree mortality for more than 100,000 forest plots from 2000 through 2018. They combined these sources with satellite measurements of the water content in forest canopies.Two clear tends emerged. "We found that generally trees seem to become more vulnerable to stress after multiple droughts, especially conifers," Anderegg said.The second finding, the researchers believe, comes down to basic physiology. Conifers and their kin have different vascular systems than broadleaf trees, or "angiosperms." As a result, they may sustain more damage in an initial drought and be at a disadvantage compared to angiosperms during subsequent periods of drought stress. The tree ring data bears this out, showing that conifers that survived a drought grew much more slowly, especially if another drought settled in."By contrast, angiosperms have much more flexible anatomy and physiology, and this seems to help them recover faster and more fully after initial droughts," Anderegg said.Anderegg was particularly surprised by the impact repeated drought had on the Amazon Rainforest. "We tend to think of these forests as not very impacted by drought and, due to their high tree diversity, able to recover quickly," he said. "But our results indicate the Amazon has been hit hard by three very severe droughts in the past 15 years."Forests are complex systems, and a variety of factors ultimately dictate how they respond to extreme events. "In terms of damage you need to not only think about it at the individual level, but at the forest level as well," said Trugman. So, although they will need time to recover from an extreme drought, surviving trees will face less competition for water resources than they had before. This could leave them in a better situation if drought returns to the area.What's more, natural selection will drive the forest as a whole to transition toward more resilient individuals, or even to more drought tolerant species overall. Repeated droughts affect forest pests and pathogens as well, and their response to these conditions will also influence how forests behave.Scientists are still working to untangle the conditions under which each of these factors rises to the top. "This [study] provides a lot of motivation," said Trugman, "but I think the next pressing step is to get at the underlying mechanisms at a physiological level and ecological level."Researchers can use these insights to improve computer models and make more accurate forecasts about the future of forests in a changing climate. "Climate change is going to bring more frequent droughts," Anderegg said, "so we have to understand and be able to forecast how forests will respond to multiple droughts."These results are especially crucial in the western U.S.," he added, "where we've had a number of major droughts in the past 20 years.
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Climate
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October 9, 2020
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https://www.sciencedaily.com/releases/2020/10/201009121932.htm
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Climate patterns linked in Amazon, North and South America, study shows
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University of Arkansas researchers have established a link between climate patterns in the Amazon and large parts of North and South America using their newly developed tree-ring chronology from the Amazon River basin.
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The discovery helps researchers better understand large-scale climate extremes and the impact of the El Niño phenomenon.Tree growth is a well-established climate proxy. By comparing growth rings in Cedrela odorata trees found in the Rio Paru watershed of the eastern Amazon River with hundreds of similar chronologies in North and South America, scientists have shown an inverse relationship in tree growth, and therefore precipitation patterns, between the areas. Drought in the Amazon is correlated with wetness in the southwestern United States, Mexico and Patagonia, and vice versa.The process is driven by the El Niño phenomenon, which influences surface-level winds along the equator, researchers said. El Niño is the name given to a large-scale irregularly occurring climate pattern associated with unusually warm water in the Pacific Ocean."The new Cedrela chronologies from the Amazon, when compared with the hundreds of tree-ring chronologies in temperate North and South America, document this Pan American resonance of climate and ecosystem extremes in the centuries before widespread deforestation or human-caused climate change," said Dave Stahle, Distinguished Professor of geosciences and first author of a study documenting the findings in the journal The connection was not documented until researchers at the University of Arkansas Tree Ring Laboratory, along with colleagues from Brazil and Argentina, developed rainfall reconstructions from growth rings in Cedrela trees. Most rainfall records in the Amazon only date back about 70 years, but Cedrelas live for 200 to 300 years, providing valuable rainfall proxies that pre-date human-influenced climate change.In the past 40 years, drought and flood extremes have increased in the Amazon basin, the researchers noted, raising the question of whether human-induced climate change and deforestation are affecting Amazon climate. While that remains an open question, the longer Cedrela-based precipitation record indicates that periods of rainfall extremes occurred in the past and the current extremes might be partly due to natural climate rhythms.The study will help researchers better understand an area of unequaled biodiversity. The Amazon is home to an estimated 16,000 species of trees and one-tenth of all known species found on the planet, Stahle noted. "The long climate history written in the growth rings of old Cedrela trees in Amazonia will surely be important to the sustainability of the biome."Video:
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Climate
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October 9, 2020
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https://www.sciencedaily.com/releases/2020/10/201009114206.htm
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Meltwater lakes are accelerating glacier ice loss
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Meltwater lakes that form at glacier margins cause ice to recede much further and faster compared to glaciers that terminate on land, according to a new study. But the effects of these glacial lakes are not represented in current ice loss models, warn the study authors.
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Therefore, estimates of recession rates and ice mass loss from lake-terminating glaciers in the coming decades are likely to be under-estimated.Many mountain glaciers now terminate in such lakes, formed as meltwater becomes trapped behind ridges of glacier debris. They are known as proglacial lakes. Climate change has increased glacier melt worldwide and this in turn has led to a dramatic increase in the size and number of proglacial lakes. But the effects of proglacial lakes on the rates of deglaciation and on glacier behaviour have previously been poorly understood.Now, an international team of researchers, led by the University of Leeds, has quantified for the first time the influence of proglacial lakes on mountain glaciers using computer simulations. They found that the presence of a proglacial lake causes a glacier to recede more than four times further and accelerate ice flow by up to eight times when compared to the same glacier terminating on land under the same climate.The findings, published today in the journal Study lead author Dr Jenna Sutherland undertook this research while a PhD candidate in the School of Geography at Leeds. She said: "An ice cube in a bowl of water is going to melt much more quickly than an ice cube sitting on a table, and the effect proglacial lakes have on glacier ice is roughly the same."The simulations show that the influence of a proglacial lake on a glacier predominantly takes place over decades to centuries rather than over millennia, meaning the glacier recedes much faster than it ever could from climatic changes alone."Study co-author Dr Jonathan Carrivick, a senior lecturer in geomorphology at Leeds, said: "Our findings suggest that simulations of past, contemporary or future glaciers ignore the effects of ice-contact lakes and will likely mis-represent the timing and rate of recession, especially the changes to the timing and rate that will occur once a proglacial lake forms."This effects need to be included in all future models and simulations if we are to have an accurate global picture of glacial ice loss."The team used the BISICLES ice-flow model, to analyse the effects of a proglacial on the Pukaki Glacier, New Zealand, during recession from the end of the last ice age.Study co-author James Shulmeister from the University of Canterbury, New Zealand said: "While this study focussed on New Zealand, proglacial lakes are prevalent during glacial retreat worldwide and this paper should therefore be of global interest and importance."In addition, he noted: "This study is also critical because the timing of ice retreat is often used to determine the synchrony or lack thereof of in climate events globally. Major inferences have been made about the roles of phenomena like oceanic circulation in affecting the global climate system from glacial retreat timings. If the timings are wrong, the relationship between these processes may need to be re-examined."
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Climate
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October 9, 2020
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https://www.sciencedaily.com/releases/2020/10/201009094946.htm
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Future ocean conditions could cause significant physical changes in marine mussels
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The increased temperature and acidification of our oceans over the next century have been argued to cause significant physical changes in an economically important marine species.
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Scientists from the University of Plymouth exposed blue mussels (Initial comparison of mussel shells showed that warming alone led to increased shell growth, but increasing warming and acidification led to decreased shell growth indicating that OA was dissolving their shells.However, analysis using cutting edge electron microscopy of the shell crystal matrix or 'ultrastructure' revealed that, in fact, warming alone has the potential to significantly alter the physical properties of the mussels' shells, whereas acidification mitigated some of the negative effects.Mussels grown under warming exhibited changes in their crystal structures including a propensity for increased brittleness, which would place mussels under greater threat from their many predators including crabs and starfish.These negative effects were to some degree mitigated under acidified conditions with mussel shells showing evidence of repair, even though their crystals grew differently to the norm.The study, published in a Previous projects have suggested future conditions could significantly reduce the nutritional qualities of oysters as well as dissolving the shells of sea snails and reducing their overall size by around a third.Dr Antony Knights, Associate Professor in Marine Ecology and the study's lead author, said: "By the end of the century, we are predicted to see increases in sea surface temperature of 2-4°C and at least a doubling of atmospheric CO2. It is no surprise that would have an effect on marine species, but this research is surprising in that acidification appears to mitigate changes in shell structure attributable to rising sea temperatures, which is counter to what we would have predicted. It may be that increased CO2 in the water is providing more 'raw material' for the mussels to repair their shells that is not available under just warming conditions."Dr Natasha Stephen, Director of Plymouth Electron Microscopy Centre, added: "Until now, there have been relatively few studies assessing the combined effects of ocean acidification and warming on shell structures. However, understanding the changes that might result at a microscopic level may provide important insights in to how organisms will respond to future climate change. This study shows it can certainly have negative effects but also that they are not always predictable, which presents some serious challenges when it comes to trying to disentangle the consequences of climate change."
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Climate
| 2,020 |
October 9, 2020
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https://www.sciencedaily.com/releases/2020/10/201009093544.htm
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Droughts are threatening global wetlands
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University of Adelaide scientists have shown how droughts are threatening the health of wetlands globally.
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Published in the journal "Wetlands around the world are incredibly important for maintaining our planet's biodiversity and they store vast amounts of carbon that can help fight climate change," says project leader Associate Professor Luke Mosley, from the University's Environment Institute and School of Biological Sciences."Globally, wetlands cover an area greater than 12.1 million square kilometres and deliver at least A$37.8 trillion (Int$27 trillion) in benefits per year, such as for flood mitigation, food production, water quality improvement and carbon storage."Wetlands can suffer "water droughts" both from the effects of a drier climate, and also when excessive water is extracted or diverted that would normally flow into them.The review paper describes how drought often leads to severe cracking and compaction, acidification, loss of organic matter, and enhanced greenhouse gas (for example methane) emissions. In some cases droughts can lead to very long-term (>10 years) and irreversible soil changes, with major impacts on water quality when soils are rewet after the drought ends."We have seen many examples of how drought in the Murray-Darling Basin has caused major issues including acidification of soil and water due to acid sulfate soils exposure in wetlands. This review highlights substantial gaps in our global understanding of the effects of drought on wet soils and how they will respond to increasing drought," says Associate Professor Mosley, who is also Deputy Director of the Acid Sulfate Soils Centre.Effects can be different in different soil types and different regions of the world. The spatial distribution of drought studies shows there has been limited assessment in a large number of regions, including south and central America, Africa, the Middle East, Asia and Oceania. Many of these regions are predicted to be vulnerable to drought impacts due to climate change.Lead author Dr Erinne Stirling, from Zhejiang University (China) and the University of Adelaide, says one of the most pressing findings from this review is that there are huge swaths of the world where there is no readily available published research on drought-affected wet soils.And secondly, she says, there is effectively no applied research into water management outcomes for wetlands and wetland soils."At a global level, wet soils are highly vulnerable to the effects of climate change and need to be protected given the very high environmental and socio-economic values they support. It is our sincere hope that the information in this review contributes to protecting these valuable ecosystems," says Dr Stirling.
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Climate
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October 9, 2020
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https://www.sciencedaily.com/releases/2020/10/201009084936.htm
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The Colorado river's water supply is predictable owing to long-term ocean memory
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A team of scientists at Utah State University has developed a new tool to forecast drought and water flow in the Colorado River several years in advance. Although the river's headwaters are in landlocked Wyoming and Colorado, water levels are linked to sea surface temperatures in parts of the Pacific and Atlantic oceans and the water's long-term ocean memory. The group's paper, "Colorado River water supply is predictable on multi-year timescales owning to long-term ocean memory" was published October 9 by
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The Colorado River is the most important water resource in the semi-arid western United States and faces growing demand from users in California, Arizona, New Mexico, Colorado and Utah. Because water shortages in the Colorado River impact energy production, food and drinking water security, forestry and tourism, tools to predict drought and low water levels could inform management decisions that affect millions of people.Current drought forecasts focus on short-term indicators which limits their usefulness because short-term weather phenomena have too great an influence on the models."This new approach is robust and means that water managers, for the first time, have a tool to better estimate water supply in the Colorado River for the future," Robert Gillies, professor in USU's Department of Plants, Soils and Climate (PSC) and director of the Utah Climate Center, said. "The model can be run iteratively so every year a new forecast for the next three years can be created."In addition to ocean memory, water flows are impacted by land systems -- including soils, groundwater, vegetation, and perennial snowpack -- which play important roles in tempering the effects of short-term precipitation events. The researchers hypothesized that multi-year predictions could be achieved by using long-term ocean memory and associated atmospheric effects and the filtering effects of land systems.The study's lead author, Yoshimitsu Chikamoto, assistant professor of earth systems modeling in USU's PSC department, said the components of the complex climate model include simulations of clouds and aerosols in the atmosphere, land surface characteristics, ocean currents and mixing and sea surface heat and water exchange."These predictions can provide a more long-term perspective," Chikamoto said. "So if we know we have a water shortage prediction we need to work with policymakers on allocating those water resources."Simon Wang, USU professor of climate dynamics, said water managers and forecasters are familiar with El Niño and La Niña and the ocean's connections to weather in the southwestern U.S. However, the upper basin of the Colorado River is not in the southwest and forecasts have not connected the dynamics of parts of the oceans with the Colorado River as the new forecasting tool does.Matt Yost, PSC assistant professor and USU Extension agroclimate specialist, said having a two-year lead-time on preparing for drought could have a huge impact on farmers as they plan crop rotations and make other business decisions.Co-author Larissa Yocom, assistant professor of fire ecology in USU's Department of Wildland Resources, said a tool that can provide a long-term forecast of drought in areas impacted by the Colorado River could give managers a jump-start in preparing for wildland fire seasons.Wang said Utah Climate Center researchers have developed models of drought cycles in the region and have recently studied the dynamics of river flows and shrinking water levels in the Great Salt Lake."In doing that work, we know that water managers don't have tools to forecast Colorado River flows very long into the future and that is a constraint on what they can do," Wang said. "We have built statistical models in the past, and Yoshi (Chikamoto) has expertise and in-depth knowledge of ocean dynamics so we talked about giving this idea a try because we found nothing in the literature to model these dynamics in the upper basin.""Using our tool we can develop an operational forecast of the Colorado River's water supply," Chikamoto added
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Climate
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October 8, 2020
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https://www.sciencedaily.com/releases/2020/10/201008142102.htm
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Heat has stronger effect on health in less developed cities, study finds
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Compared to high income cities, less developed cities in Brazil have a higher hospitalization rate associated with increased heat exposure, according to a new study published this week in
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Heat exposure, which will increase with global warming, is associated with increases in mortality and morbidity but little is known about the socioeconomic disparities in vulnerability to heat. In the new study, researchers collected daily hospitalization and climate data in the hot season during 2000 through 2015 from 1,814 Brazilian cities covering 78.4% of the Brazilian population. 49 million hospitalizations were studied.For cities of lower middle income, as classified by the World Bank, every 5°C increase in daily mean temperature during the hot season was associated with 5.1% (95%CI 4.4-5.7, p<0.001) increase in all-cause hospitalization. For cities of middle income, every 5°C temperature increase was associated with a 3.7% (95%CI 3.3-4.0, p<0.001) increase in hospitalization. While for cities of high income, the temperature increase was only associated with a 2.6% (95%CI 1.7-3.4, p<0.001) increase in hospitalization. The inter-city disparities in the association were strongest for children and adolescents, and the disparities were particularly evident for certain diseases including heart disease, asthma, pneumonia, renal diseases, mental health conditions and neoplasms."Increasing heat exposure along with global warming could be a potential driver for exacerbating inter-city health inequalities," the authors say. "More attention should be paid to less developed cities in Brazil to tackle the morbidity burden of heat exposure, in order to promote health equity under a global warming trend."
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Climate
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October 8, 2020
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https://www.sciencedaily.com/releases/2020/10/201008124430.htm
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Deep-seabed mining lastingly disrupts the seafloor food web
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The deep sea is far away and hard to envision. If imagined it seems like a cold and hostile place. However, this remote habitat is directly connected to our lives, as it forms an important part of the global carbon cycle. Also, the deep seafloor is, in many places, covered with polymetallic nodules and crusts that arouse economic interest. There is a lack of clear standards to regulate their mining and set binding thresholds for the impact on the organisms living in affected areas.
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An international team of scientists around Tanja Stratmann from the Max Planck Institute for Marine Microbiology in Bremen, Germany, and Utrecht University, the Netherlands, and Daniëlle de Jonge from Heriot-Watt University in Edinburgh, Scotland, has investigated the food web of the deep seafloor to see how it is affected by disturbances such as those caused by mining activities.For this, the scientists travelled to the so-called DISCOL area in the tropical East Pacific, about 3000 kilometres off the coast of Peru. Back in 1989, German researchers had simulated mining-related disturbances in this manganese nodule field, 4000 metres under the surface of the ocean, by ploughing a 3.5 km wide area of seabed with a plough-harrow. "Even 26 years after the disturbance, the plough tracks are still there," Stratmann described the site. Previous studies had shown that microbial abundance and density had undergone lasting changes in this area. "Now we wanted to find out what that meant for carbon cycling and the food web of this deep ocean habitat.""We looked at all different ecosystem components and on all levels, trying to find out how they work together as a team," de Jonge explained who carried out the project as part of her Master's Thesis at the NIOZ Royal Netherlands Institute for Sea Research and the University of Groningen, The Netherlands. The scientists quantified carbon fluxes between living and non-living compartments of the ecosystem and summed them up as a measure of the "ecological size" of the system.They found significant long-term effects of the 1989 mining simulation experiment. The total throughput of carbon in the ecosystem was significantly reduced. "Especially the microbial part of the food web was heavily affected, much more than we expected," said Stratmann. "Microbes are known for their fast growth rates, so you'd expect them to recover quickly. However, we found that carbon cycling in the so-called microbial loop was reduced by more than one third."The impact of the simulated mining activity on higher organisms was more variable. "Some animals seemed to do fine, others were still recovering from the disturbance. The diversity of the system was thus reduced," said de Jonge. "Overall, carbon flow in this part of the food web was similar to or even higher than in unaffected areas."The simulated mining resulted in a shift in carbon sources for animals. Usually, small fauna feed on detritus and bacteria in the seafloor. However, in the disturbed areas, where bacterial densities were reduced, the fauna ate more detritus. The possible consequences of this will be part of de Jonge's PhD Thesis, which she just started. "Future climate scenarios predict a decrease of the amount and quality of detritus reaching the seafloor. Thus this shift in diet will be especially interesting to investigate in view of climate change," she looks forward to the upcoming work."You also have to consider that the disturbance caused by real deep-seabed mining will be much heavier than the one we're looking at here," she added. "Depending on the technology, it will probably remove the uppermost 15 centimeters of the sediment over a much larger area, thus multiplying the effect and substantially increasing recovery times."Polymetallic nodules and crusts cover many thousands of square kilometres of the world's deep-sea floor. They contain mainly manganese and iron, but also the valuable metals nickel, cobalt and copper as well as some of the high-tech metals of the rare earths. Since these resources could become scarce on land in the future -- for example, due to future needs for batteries, electromobility and digital technologies -- marine deposits are economically very interesting. To date, there is no market-ready technology for deep-sea mining. However, it is already clear that interventions in the seabed have a massive and lasting impact on the affected areas. Studies have shown that many sessile inhabitants of the surface of the seafloor depend on the nodules as a substrate, and are still absent decades after a disturbance in the ecosystem. Also, effects on animals living in the seabed have been proven.
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Climate
| 2,020 |
October 8, 2020
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https://www.sciencedaily.com/releases/2020/10/201008083758.htm
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Double jeopardy for ecologically rare birds and terrestrial mammals
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Common assumptions notwithstanding, rare species can play unique and essential ecological roles. After studying two databases that together cover all known terrestrial mammals and birds worldwide, scientists from the CNRS, the Foundation for Biodiversity Research (FRB), Université Grenoble Alpes, and the University of Montpellier[1] have demonstrated that, though these species are found on all continents, they are more threatened by human pressures than ecologically common species and will also be more impacted by future climate change. Thus they are in double jeopardy. The researchers' findings, published in
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It has long been thought that rare species contribute little to the functioning of ecosystems. Yet recent studies have discredited that idea: rarity is a matter not only of the abundance or geographical range of a species, but also of the distinctiveness of its ecological functions. Because these functionally distinct species are irreplaceable, it is essential we understand their ecological characteristics, map their distributions, and evaluate how vulnerable they are to current and future threats.Using two databases that collect information on the world's terrestrial mammals (4,654 species) and birds (9,287 species), scientists from the FRB's Centre de Synthèse et d'Analyse de la Biodiversité (CESAB), CNRS research laboratories, Université Grenoble Alpes, the University of Montpellier, and partner institutes divided the earth's surface into 50 × 50 km squares and determined the number of ecologically rare species within each. They showed that ecological rarity among mammals is concentrated in the tropics and the southern hemisphere, with peaks on Indonesian islands, in Madagascar, and in Costa Rica. Species concerned are mostly nocturnal frugivores, like bats and lemurs, and insectivores, such as small rodents. Ecologically rare bird species are mainly found in tropical and subtropical mountainous regions, especially in New Guinea, Indonesia, the Andes, and Central America. The birds in question are essentially frugivorous or nectarivorous, hummingbirds being an example. For birds and terrestrial mammals alike, islands are hotspots of ecological rarity.The researchers also ranked these species according to their IUCN Red List status[2] and found they made up the bulk of the threatened species categories. That is, ecologically rare mammals account for 71% of Red List threatened species (versus 2% for ecologically common mammals); and ecologically rare birds, 44.2% (versus 0.5% for ecologically common birds). For each species, they determined (i) anthropogenic pressure exerted; (ii) human development indexes (HDIs) of host countries; and (iii) exposure to armed conflicts. The last two of these elements shape conservation policies. The scientists observed that human activity had a greater impact on ecologically rare mammals and birds than on more common species, and that these rare species were found in countries of every kind of profile, irrespective of HDI or the prevalence of warfare.[3] They used models to demonstrate that ecologically rare species will be the greatest victims of climate change, many of them facing extinction within 40 years.This profiling of ecologically rare species makes it clear that current conservation efforts, even in zones already protected, are insufficient. Conservation strategies still too often ignore functional distinctiveness and focus instead on population sizes. But it is essential to take this distinctiveness into account, letting this knowledge guide steps taken to protect these rare species. As they are necessary for healthy ecosystems, a true paradigm shift in conservation policy is needed to ensure their survival.1These scientists are affiliated with the following research units: the Centre for Marine Biodiversity, Exploitation and Conservation (CNRS / University of Montpellier / IRD / IFREMER), the Centre d'Écologie Fonctionnelle et Évolutive (CNRS / University of Montpellier / Paul Valéry University / EPHE / IRD), the Laboratoire d'Écologie Alpine (CNRS / Université Grenoble Alpes / Université Savoie Mont Blanc), and the Centre de Synthèse et d'Analyse sur la Biodiversité (CESAB) at the FRB. This research is the product of FREE, a CESAB team dedicated to the coherent integration of biodiversity data. FREE is jointly funded by the FRB and EDF.2The International Union for Conservation of Nature (IUCN) is a leading international NGO focused on nature conservation. It evaluates the risk of extinction faced by different species, assigning each to a particular category (e.g., 'Least Concern', 'Near Threatened', 'Vulnerable', 'Endangered', or 'Extinct').3For example, the Philippines, where HDI is low and armed conflicts prevalent, are a hive for ecologically rare species (19 terrestrial mammals and 15 birds). Yet Australia, where HDI is high and armed conflict rare, is also home to many ecologically rare species (10 terrestrial mammals and 10 birds).
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Climate
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October 7, 2020
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https://www.sciencedaily.com/releases/2020/10/201007145307.htm
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Polar ice, atmospheric water vapor biggest drivers of variation among climate models
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A Florida State University researcher is part of a team that has found varying projections on global warming trends put forth by climate change scientists can be explained by differing models' predictions regarding ice loss and atmospheric water vapor.
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The work will help climate scientists reconcile various models to improve their accuracy, said Florida State University Meteorology Professor Ming Cai, one of the authors of the study published in Climate scientists agree that the Earth's surface temperature is warming, but the details of exactly where and by how much are less clear. A worst-case climate change scenario (known as the "Representative Concentration Pathway 8.5") predicted a likely increase in average global temperatures of about 2.6 degrees Celsius to 4.8 degrees Celsius (or about 4.7 degrees Fahrenheit to 8.6 degrees Fahrenheit) by 2100."This uncertainty limits our ability to foresee the severity of the global warming impacts on nature and human civilization," Cai said. "The more information we have about the effects of climate change around the world, the better prepared we will be."The difference in those conclusions would mean the difference between a sea level rise of about a half-meter to close to one meter, for example.As scientists around the world have studied the climate, they have developed their own models. Although the major components of these climate models are based on the same general physical principles, such as conservations of energy and mass, they still differ from one another in many details, which is what leads to a range of conclusions about something like the future average global temperature."What are the best ways to represent those details in a climate model?" Cai said. "That's something that climate science is still working to answer. The model gets into the 'art' part of science."The researchers investigated the variability among 25 climate models that participated in the United Nations' Intergovernmental Panel on Climate Change. They found that climate models that predicted higher average temperatures for the Earth's surface overall also yielded results that showed more polar ice loss and more water vapor in the atmosphere."We found that these two factors explain close to 99 percent of the difference in global-mean warming forecasts among these 25 climate models," Cai said. "Our findings suggest that variability among climate models could be significantly reduced by narrowing the uncertainty in models simulating ice-albedo and water vapor feedbacks."The research also found that cloud cover is less important than scientists previously thought for explaining variation among models.These models are tools for making forecasts for things like sea level rise, flood risk, the viability of crops and wildlife and other considerations."Knowing that polar ice and water vapor in the atmosphere are the most important drivers of variability in different climate models will help climate scientists further refine those models," Cai said.Researchers from Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory in China, Science Systems and Applications Inc. in Hampton, Virginia, and NASA contributed to this study.This research was funded in part by the U.S. National Science Foundation, NASA and the National Natural Science Foundation of China.
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Climate
| 2,020 |
October 7, 2020
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https://www.sciencedaily.com/releases/2020/10/201007123131.htm
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Nitrous oxide emissions pose an increasing climate threat, study finds
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Rising nitrous oxide (N
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The growing use of nitrogen fertilizers in the production of food worldwide is increasing atmospheric concentrations of NPublished today in the journal The aim was to produce the most comprehensive assessment to date of all global sources and sinks of NThe study points to an alarming trend affecting climate change: NProf Hanqin Tian, director of the International Center for Climate and Global Change Research at Auburn University's School of Forestry and Wildlife Sciences, co-led the study."The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions," said Prof Tian. "There is a conflict between the way we are feeding people and stabilizing the climate."Like COLead UK author Dr Parvadha Suntharalingam, of UEA's School of Environmental Sciences, said: "This study presents the most comprehensive and detailed picture to date, of N"This new analysis identifies the factors driving the steadily increasing atmospheric levels of NThe study presents a comprehensive global NHuman-induced emissions, which are dominated by nitrogen additions to croplands, increased by 30 per cent over the past four decades to 7.3 teragrams of nitrogen per year.The analysis also reveals an emerging NThe study found that the largest contributors to global NHowever, NStudy co-leader Dr Josep 'Pep' Canadell, of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, is executive director of the Global Carbon Project. He said: "This new analysis calls for a full-scale rethink in the ways we use and abuse nitrogen fertilizers globally and urges us to adopt more sustainable practices in the way we produce food, including the reduction of food waste."These findings underscore the urgency and opportunities to mitigate nitrous oxide emissions worldwide to avoid the worst of climate impacts."
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Climate
| 2,020 |
October 7, 2020
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https://www.sciencedaily.com/releases/2020/10/201007123129.htm
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Researchers find consistent mercury levels in Arctic seals
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Ringed seals and other Arctic marine mammals are important in the diet of Arctic Indigenous peoples. A study spanning 45 years of testing indicates that mercury concentrations in ringed seals from the Canadian Arctic have remained stable, showing very limited declines over time.
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The authors of the "Ringed seal is an important species for contaminants surveillance and monitoring across the Arctic. With the collaboration and support of Inuit communities, we've been able to study contaminants in seals for decades in Canada," said corresponding author Magali Houde, PhD, of Environment and Climate Change Canada. "Levels of mercury have not changed much in ringed seals through time. Our result suggest that climate factors could be influencing the accumulation of mercury in seals."
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Climate
| 2,020 |
October 7, 2020
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https://www.sciencedaily.com/releases/2020/10/201007123112.htm
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Broken promises: Almost 80 percent of threatened species lack sufficient protection
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A failure by governments to deliver on commitments under a global nature conservation treaty, the Convention on Biological Diversity, could have devastating effects.
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The warning comes after a consortium of scientists, led by Dr Sean Maxwell and Professor James Watson from The University of Queensland, reviewed national area-based conservation efforts, including protected areas.In 2010, almost all nations agreed that area-based conservation efforts must cover at least 17 per cent of land and 10 per cent of ocean by 2020, in areas that are important for biodiversity and ecosystem services."We reviewed progress toward this target by overlaying maps of protected areas on natural ecosystems, threatened species, carbon services on land and sea and fisheries productivity in the world's oceans," Dr Maxwell said."We found some welcome progress -- particularly in the marine realm -- since global environmental targets were agreed."But terrestrial protected area expansion needed to be double what it was in the past decade in order to achieve 17 per cent coverage for land and freshwater environments."There is also alarming shortfalls in ecological representation and management effectiveness, and measurable biodiversity outcomes persist in area-based conservation efforts."We found that 78 per cent of known threatened species and more than half of all ecosystems on land and sea remain without adequate protection."And seven of the world's most productive at-sea fisheries have no formal protected area coverage."The researchers also reviewed how effective and equitable protected area management has been, given these criteria featured in the 2010 targets."We know that adequately funding protected areas are one of our best tools for reducing threats to biodiversity," Dr Maxwell said."Yet the current financial shortfall for area-based conservation likely exceeds the multi-billion dollar mark, and as much as 90 per cent have inadequate or below optimum on-site staff capacity.Professor Watson, of UQ and the Wildlife Conservation Society, said the next round of conservation targets, which were meant to be set this year, is fundamental to the future of global biodiversity."It is obvious that governments have dramatically underinvested in protected areas and been weak in legally protecting them," Professor Watson said."For biodiversity to have any chance to survive climate change, nations must invest more resources in consolidating area-based conservation efforts and ensuring biodiversity conservation is a far stronger part of managed land and seas."There are significant opportunities to better recognise and support conservation by indigenous peoples, local communities and private actors, and we now need to embrace new models for land stewardship that rewards good behaviour by farmers, developers and miners."
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Climate
| 2,020 |
October 7, 2020
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https://www.sciencedaily.com/releases/2020/10/201007123029.htm
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Climate change could mean fewer sunny days for hot regions banking on solar power
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While solar power is a leading form of renewable energy, new research suggests that changes to regional climates brought on by global warming could make areas currently considered ideal for solar power production less viable in the future.
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Princeton-based researchers recently published in the journal Their study found that higher surface temperatures -- and the resulting increase in the amount of moisture, aerosols and particulates in the atmosphere -- may result in an overall decrease in solar radiation and an uptick in the number of cloudy days. Hot, arid regions such as the Middle East and the American Southwest -- considered among the highest potential producers of solar energy -- were most susceptible to greater fluctuations in sunlight, the researchers found."Our results could help in designing better solar power plants and optimizing storage while also avoiding the expansion of solar power capacity in areas where sunlight intermittency under future climate conditions may be too high to make solar reliable," said corresponding author Amilcare Porporato, Princeton's Thomas J. Wu '94 Professor of Civil and Environmental Engineering and the Princeton Environmental Institute (PEI). The research was supported by the Carbon Mitigation Initiative based in PEI."To use an academic metaphor, in terms of solar power, semiarid places are now like students who get an A nearly every day," Porporato said. "Now, climate change is disturbing the usual dynamics of the atmosphere and the regularity of the solar radiation reaching the planet's surface. We tried to quantify how much more often those A's could become B's, or even C's, as a result."Existing research on how solar energy will fare in this irregular future has largely focused on average levels of sunlight, said first author Jun Yin, a researcher at Nanjing University of Information Science and Technology who worked on the paper at Princeton as a postdoctoral research associate with Porporato."The novelty of our approach was to point out that in some places there is going to be more uncertainty in day-to-day variability," Yin said. He and Porporato previously reported that climate models underestimate the cooling effect of the daily cloud cycle. They worked on the most recent paper with co-author Annalisa Molini, an associate professor of civil infrastructure and environmental engineering at Khalifa University in the United Arab Emirates.The researchers' findings were based on probabilistic calculations similar to those used to determine the risk of flooding or drought. The reduced reliability of solar energy is related to the increased variability of atmospheric moisture and aerosols in some arid regions. Higher temperatures hold more moisture and are more turbulent, which favors the formation of clouds and keeps particles in suspension longer, Porporato said."Then there is the issue of soils drying, which may be even more important," Porporato said. As temperatures and atmospheric turbulence increase in arid regions such as the Middle East, dry soils potentially lead to greater amounts of dust and atmospheric aerosols that would diminish solar radiation. These trends are in fact already detectable in observations from climate-observation networks, Porporato said.For the American Southwest, the researchers' findings were less consistent. Some models showed more solar radiation and lower intermittency in the future, while others showed less solar radiation and higher intermittency. These results illustrate the challenge of trying to predict the reliability of solar energy in an uncertain future, Yin said."We hope that policymakers and people in the energy industry can take advantage of this information to more efficiently design and manage photovoltaic facilities," Yin said."Our paper helps identify efficient solutions for different locations where intermittency could occur, but at an acceptable level," he said. "A variety of technologies such as power storage, or power-operation policies such as smart curtailment, load shaping or geographical dispersion, are promising solutions."To follow up on their work, the researchers plan to examine climate persistency -- specifically, the number of consecutive sunny or cloudy days -- which is important for solar power. They also are exploring how clouds could affect the effectiveness of tree planting as a climate mitigation strategy. Trees absorb not only carbon dioxide but also solar energy, which would raise surface temperatures. A resulting increase in cloud coverage could change current estimates of how effective trees would be in reducing atmospheric carbon.
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Climate
| 2,020 |
October 7, 2020
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https://www.sciencedaily.com/releases/2020/10/201007085611.htm
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Sea-level rise projections can improve with state-of-the-art model
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Projections of potentially dramatic sea-level rise from ice-sheet melting in Antarctica have been wide-ranging, but a Rutgers-led team has created a model that enables improved projections and could help better address climate change threats.
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A major source of sea-level rise could come from melting of large swaths of the vast Antarctic ice sheet. Fossil coral reefs jutting above the ocean's surface show evidence that sea levels were more than 20 feet higher about 125,000 years ago during the warm Last Interglacial (Eemian) period."Evidence of sea-level rise in warm climates long ago can tell us a lot about how sea levels could rise in the future," said lead author Daniel M. Gilford, a post-doctoral associate in the lab of co-author Robert E. Kopp, a professor in the Department of Earth and Planetary Sciences within the School of Arts and Sciences at Rutgers University-New Brunswick. "This evidence suggests that as climate change drives warming in the atmosphere and oceans, future global sea-level rise could reach considerable heights."The study, published in the journal The study takes advantage of the similarities between past and potential future sea levels to train a statistical ice-sheet model, using artificial intelligence. The fast, simple, less expensive "emulator" -- a form of machine learning software -- is taught to mimic the behavior of a complex model that focuses on ice-sheet physics, enabling many more simulations than could be explored with the complex model alone. This avoids the costly run times of the complex ice-sheet model, which considers such phenomena as ice-sheet fractures due to surface melting and the collapse of tall seaside ice cliffs.What may happen to the Antarctic ice sheet as the climate warms is the biggest uncertainty when it comes to global sea-level rise this century, the study notes. When combined with evidence of past sea levels, the new model can boost confidence in sea-level rise projections through at least 2150."If big swaths of the Antarctic ice sheet melted and collapsed about 125,000 years ago, when the polar regions were warmer than today, parts of the ice sheet may be similarly prone to collapse in the future as the climate warms, affecting our expectations of sea-level rise and coastline flooding over the next 130 years," Gilford said.New estimates of sea levels about 125,000 years ago could be used to indicate whether, 75 years from now, Hurricane Sandy-like flooding (about 9 feet above ground level in New York City) is likely to occur once a century or annually along parts of the Northeast U.S. coastline. Improved projections could also be included in reports such as the Intergovernmental Panel on Climate Change's upcoming Sixth Assessment Report, likely helping officials and others decide how to address climate change threats.Co-authors include Erica L. Ashe, a post-doctoral scientist in Kopp's lab, along with scientists at the University of Massachusetts Amherst, Pennsylvania State University and the University of Bremen.
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Climate
| 2,020 |
October 6, 2020
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https://www.sciencedaily.com/releases/2020/10/201006153522.htm
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New climate model helps researchers better predict water needs
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New research from the FAMU-FSU College of Engineering combines climate and land use projections to predict water availability, information that is crucial for the preparations of resource managers and land-use planners.
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"This research presented a new method that can be used to generate future climate data for the existing hydrological models," said Gang Chen, a professor of civil and environmental engineering at the college. "With the integration of more reliable future climate data, the existing hydrological models can more accurately project future water scenarios in the face of climate change."Chen is leading a team of experts to produce new data techniques to improve hydrological modeling that is essential for water resource management planning. Their work was published in The researchers used their method to examine the hydrological processes in Alabama's Upper Choctawhatchee River Watershed, which eventually flows into Florida and empties into the Choctawhatchee Bay. They integrated land use projections with future climate data to study the combined effects on the hydrological response of the watershed."Using water balance simulations, we discovered that surface runoff and evapotranspiration are dominant pathways for water loss in the Southeast," Chen said.Yashar Makhtoumi, a doctoral candidate in the Department of Civil and Environmental Engineering, is working with Chen on new data downscaling techniques. The innovative process provides more data and improves modeling outcomes."Few research projects have been done to investigate the combined effects of land use change and climate change using projections," Makhtoumi said.The results of the study showed the effects on water resource variables were seasonal. Surface runoff caused the most significant changes in various simulations, and evapotranspiration was also an issue, though to a lesser degree. The models indicate that by midcentury, more frequent extremes in water balance are projected to be an issue.Although the research focuses on a single watershed, the researchers believe their work could be applicable on a wider scale. That's important for a state like Florida, where population growth, development and climate change are forcing residents and planners to realize the limitations of the state's water supply."Our model demonstrated that it could capture hydrologic parameters accurately and could be used for future studies of water quality," Chen said. "It can provide the necessary data to determine sustainable conservation practices needed now and in the future, and help manage and protect our water resources."Researchers from Florida A&M University and California State Polytechnic University Pomona contributed to this work.The research was supported by a $1.2 million grant from the National Institute of Food and Agriculture of the U.S. Department of Agriculture through Florida A&M University.
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Climate
| 2,020 |
October 6, 2020
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https://www.sciencedaily.com/releases/2020/10/201006132115.htm
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Indonesia's old and deep peatlands offer an archive of environmental changes
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Researchers probing peatlands to discover clues about past environments and carbon stocks on land have identified peatland that is twice as old and much deeper than previously thought.
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Their findings, detailed in an open-access paper published Sept. 14 in the journal The study provides new insights about the climate of equatorial rainforests, especially during the last ice age, said study co-author Dan Gavin, a professor of geography at the University of Oregon."This existence of this very deep and old peatland provides some clues on past climate," Gavin said. "It tells us that this area remained sufficiently wet and warm to support peat growth through the last ice age. The climate during that time is still poorly understood as there are few places in the very-wet tropics, where there is no dry season, that have such long sediment archives."For the study, the research team, led by Monika Ruwaimana, a doctoral student at the UO and lecturer at Indonesia's Universitas Atma Jaya Yogyakarta, collected peat cores from two inland and three coastal sites associated with the Kapuas River in West Kalimantan, a province of Indonesia on Borneo.The Putussibau site has not been as disturbed as most other areas of Indonesia by deforestation and land conversion to agriculture."We thought the Putussibau site would be thinner because people had already built roads over it," Ruwaimana said. "But surprisingly we found depths of 17 to 18 meters. As comparison, the average peat depth in Indonesia is 5 to 6 meters."In contrast, the coastal sites, particularly in the Kapuas River delta, contain shallower peatland that didn't begin forming until after the last ice age and after sea level stabilized between 4,000 and 7,000 years ago.The lower base of the inlet peats that were examined is lower than the current riverbed, noted co-author Gusti Z. Anshari of the Universitas Tanjungpura in Pontianak, Indonesia."The inland peat contains an important archive about past hydrology and climates," he said. "The coastal peat bed is higher than the current riverbed, making it prone to dryness. The coastal peat burns every dry season because of water loss through hydrological conductivity."Human disturbances related to land-use changes, he added, have caused high carbon emissions and create fire-loving degraded peats."The inland peat possibly played an important role in climate and carbon storage before and during the last ice age," Ruwaimana said.During that glaciation, she noted, atmospheric carbon dioxide was much lower and previous evidence suggested that much of the region's carbon had moved into the oceans. The new findings, however, show inland peatlands persisted.Across the sites, 37 radiocarbon dates were obtained. During a cool, dry period 20,000-30,000 years ago, Ruwaimana said, the new dating synthesized with previous dating across Indonesia indicated a hiatus of peatland formation."The significance is that conditions must have remained sufficiently wet so that the peat in the upper Kapuas was not lost during this period," she said. "The ages provide a clearer picture on its formation history and how it connects to the past climate. As this peat forms layer by layer like a pancake layer cake, each layer tells us the story about fire, plant and climate when that layer was formed."With the revised depths of inland peatlands at these sites, the researchers suggest that previous estimates of carbon storage -- 25.3 gigatons across Indonesia and 9.1 gigatons on Borneo -- are too low. However, Ruwaimana said, more data is needed across the region for more accurate calculations.Depths of the older peats obtained in the study, she noted, varied dramatically, with some peats of less than two meters depth being more than 10,000 years old.The inland sites, the researchers wrote, may be the oldest tropical peats and contain the largest density of carbon in the world but are increasingly being threatened by changes in land use.Lucas Silva, a professor of geography and head of the UO's Soil Plant Atmosphere research lab, also was a co-author on the study.
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Climate
| 2,020 |
October 6, 2020
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https://www.sciencedaily.com/releases/2020/10/201006114312.htm
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Warmer winters are keeping some lakes from freezing
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Warmer winters due to climate change are causing lakes in the Northern Hemisphere to experience more ice-free years, according to a new study.
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Researchers recently analyzed nearly 80 years of lake ice data, stretching from 1939 to 2016, for 122 lakes that typically freeze every winter. They found ice-free years have become more than three times more frequent since 1978 and 11% of lakes studied experienced at least one completely ice-free year since 1939. This trend is linked to abnormally warm winter temperatures, and the study authors project it will continue with increasing frequency due to climate change. Such ice-free years could have significant ecological, cultural and economic impacts."Lake ice is becoming increasingly absent," said Alessandro Filazzola, a community ecologist at York University and the University of Alberta in Canada and lead author of the new study in AGU's journal Communities around lakes often depend on freezing events for winter recreation activities like ice fishing and ice festivals, which can bring in hundreds of thousands of dollars in a single weekend.Lake ice also serves as an ecological "reset," said Sapna Sharma, an aquatic ecologist at Canada's York University and coauthor of the new study. Lakes are warmer in years without ice cover, and they stratify earlier, which could make them more prone to toxic algal blooms. This, in turn, can harm fish or make lakes dangerous for swimming. "The consequences are more widespread than simply one individual unable to go ice fishing," Sharma said.Interestingly, the authors saw the same warming trend regardless of location, suggesting global climate change is already having an impact on Earth's lakes. "This isn't just happening in one lake in the northern United States," Filazzola said. "It's happening in thousands of lakes around the world."In the new study, Filazzola and his colleagues wanted to understand how the frequency of lakes' ice-free years has changed over time. They selected 122 lakes in North America, Europe and Asia with a long, consistent record of data from the National Snow and Ice Data Center. The NSIDC lake ice database contains historically available data from harbors, newspapers and other written records and modern data sourced from people who live near the lakes.Lake Suwa in Japan boasts one of the oldest lake ice records in the database, stretching back to 1443. The record has been maintained by 15 generations of Shinto priests that have celebrated the appearance of lake ice each winter. Other culturally important lakes in the dataset include Lakes Baikal, Geneva, Balaton, Champlain and Michigan.Filazzola, Sharma and their colleagues analyzed ice-free years in their chosen lakes, comparing how often this extreme event occurred in the first 40 versus the last 40 years of the study period. If a lake did not have 100% ice cover for at least one day, it was considered an ice-free year. They then compared the lake ice data with local air temperatures and climate cycles like El Niño and the North Atlantic Decadal Oscillation to better understand the drivers behind lake ice changes.They found ice-free years occurred much more commonly in the second half of their study period, with 31 recorded ice-free events before 1978 and 108 ice-free events after that year. Since 1990, Lake Champlain and Grand Traverse Bay in Lake Michigan have both experienced three consecutive years without freezing. Lake Suwa, which once froze regularly, now freezes an average of two years every decade, according to the study."Even in the last 40 years versus the last 80 years, there's already an obvious pattern that's occurring and it's showing that we're already experiencing a response from warming, which will likely get worse," Filazzola said.The results showed local winter air temperatures were the best predictor of ice-free years, which became significantly more likely once average winter temperatures rose to -4 degrees Celsius (25 degrees Fahrenheit). The researchers found lakes in more southern and coastal regions were most vulnerable to experiencing ice-free years since they have high rates of warming."I think it is intuitive," Sharma said of their results. "But it also gives us a historical snapshot to understand that the climate is changing. It's not normal that these lakes are not freezing.""I am delighted by this paper," said John Magnuson, a limnologist at the University of Wisconsin Madison who has worked on past lake ice studies but was not involved in this research, calling it "a significant paper that provides new information and insights about a climate-sensitive component of lake ecosystems to climate change."
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Climate
| 2,020 |
October 6, 2020
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https://www.sciencedaily.com/releases/2020/10/201006114227.htm
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CRISPRing trees for a climate-friendly economy
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Researchers led by prof. Wout Boerjan (VIB-UGent Center for Plant Systems Biology) have discovered a way to stably finetune the amount of lignin in poplar by applying CRISPR/Cas9 technology. Lignin is one of the main structural substances in plants and it makes processing wood into, for example, paper difficult. This study is an important breakthrough in the development of wood resources for the production of paper with a lower carbon footprint, biofuels, and other bio-based materials. Their work, in collaboration with VIVES University College (Roeselare, Belgium) and University of Wisconsin (USA) appears in
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Today's fossil-based economy results in a net increase of COProf. Wout Boerjan (VIB-UGent): "A few years ago, we performed a field trial with poplars that were engineered to make wood containing less lignin. Most plants showed large improvements in processing efficiency for many possible applications. The downside, however, was that the reduction in lignin accomplished with the technology we used then -- RNA interference -- was unstable and the trees grew less tall."Undeterred, the researchers went looking for a solution. They employed the recent CRISPR/Cas9 technology in poplar to lower the lignin amount in a stable way, without causing a biomass yield penalty. In other words, the trees grew just as well and as tall as those without genetic changes.Dr. Barbara De Meester (VIB-UGent): "Poplar is a diploid species, meaning every gene is present in two copies. Using CRISPR/Cas9, we introduced specific changes in both copies of a gene that is crucial for the biosynthesis of lignin. We inactivated one copy of the gene, and only partially inactivated the other. The resulting poplar line had a stable 10% reduction in lignin amount while it grew normally in the greenhouse. Wood from the engineered trees had an up to 41% increase in processing efficiency."Dr. Ruben Vanholme (VIB-UGent): "The mutations that we have introduced through CRISPR/Cas9 are similar to those that spontaneously arise in nature. The advantage of the CRISPR/Cas9 method is that the beneficial mutations can be directly introduced into the DNA of highly productive tree varieties in only a fraction of the time it would take by a classical breeding strategy."The applications of this method are not only restricted to lignin but might also be useful to engineer other traits in crops, providing a versatile new breeding tool to improve agricultural productivity.
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Climate
| 2,020 |
October 6, 2020
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https://www.sciencedaily.com/releases/2020/10/201006114221.htm
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Who is driving whom? Climate and carbon cycle in perpetual interaction
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The current climate crisis underlines that carbon cycle perturbations can cause significant climate change. New research reveals how carbon cycle and global climate have been interacting throughout the last 35 million years of geologic history, under natural circumstances.
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Human-made global heating has long been presented as a relatively simple chain of cause and effect: humans disrupt the carbon cycle by burning fossil fuels, thereby increase the concentration of COTo reveal these kind of climate-carbon cycle feedback mechanisms under natural circumstances, David De Vleeschouwer and colleagues exploited isotopic data from deep-ocean sediment cores. "Some of these cores contain sediments of up to 35 million years old. Despite their respectable age, these sediments carry a clear imprint of so-called Milankovi? cycles. Milankovi? cycles relate to rhythmic changes in the shape of the Earth's orbit (eccentricity), as well as to the tilt (obliquity) and orientation (precession) of the Earth's rotational axis. Like an astronomical clockwork, Milankovi? cycles generate changes in the distribution of solar insolation over the planet, and thus provoke cadenced climate change," explains David De Vleeschouwer. "We looked at the carbon and oxygen isotope composition of microfossils within the sediment and first used the eccentricity, obliquity and precession cadences as geological chronometers. Then, we applied a statistical method to determine whether changes in one isotope system lead or lag variability in the other isotope."His colleague Maximilian Vahlenkamp adds: "When a common pattern in both isotope systems occurs just a little earlier in the carbon system compared to the oxygen isotope system, we call this a carbon-isotope lead. We then infer that the carbon cycle exerted control over the climate system at the time of sediment deposition." Paleoclimatologists and paleoceanographers often use carbon isotopes as an indicator of carbon-cycle perturbations, and oxygen isotopes as a proxy for changes in global climate state. Changes in the isotopic composition of these deep-sea microfossils may indicate, for example, an increase in the continental carbon storage by land plants and soils, or global cooling with a growth of ice caps."The systematic and time-continuous analysis of leads and lags between carbon cycle and climate constitutes the innovative character of this study. Our approach allows to sequence Earth's history at high resolution over the past 35 million years," says Prof Heiko Pälike. "We show that the past 35 million years can be subdivided in three intervals, each with its specific climate-carbon cycle modus operandi." On average, the authors found oxygen isotopes to lead carbon isotope variations. This means that, under natural conditions, climate variations are largely regulating global carbon cycle dynamics. However, the research team focused on times when the opposite was the case. Indeed, De Vleeschouwer and colleagues found a few examples of ancient periods during which the carbon cycle drove climate change on approximately 100,000-year timescales, just as it is the case now on much shorter timescales -- "but then of course without human intervention," states Pälike.During the oldest interval, between 35 and 26 million years ago, the carbon cycle took the lead over climate change mostly during periods of climate stability. "Periods of climate stability in the geologic record often have an astronomical cause. When the Earth's orbit around the sun is close to a perfect circle, seasonal insolation extremes are truncated and more equable climates are enforced," explains David De Vleeschouwer. "Between 35 and 26 million years ago, such astronomical configuration would have been favourable for a temporal expansion of the Antarctic ice sheet. We propose that under such a scenario, the intensity of glacial erosion and subsequent rock weathering increased. This is important, because the weathering of silicate rocks removes COBut around 26 million years ago, the modus operandi radically changed. The carbon cycle took control over climate at times of climate volatility, not stability. "We believe this change traces back to the uplift of the Himalayan mountains and a monsoon-dominated climate state. When seasonal insolation extremes are amplified through an eccentric Earth orbit, monsoons can become truly intense. Stronger monsoons permit more chemical weathering, the removal of COThe mechanisms proposed by the authors not only explain the observed patterns in carbon and oxygen isotopes, they also provide new ideas as to how the climate system and the carbon cycle interacted through time. "Some hypotheses need further testing with numerical climate and carbon cycle models, but the process-level understanding presented in this work is important because it provides a glimpse at the machinery of our planet under boundary conditions that are fundamentally different from today's," says De Vleeschouwer. Moreover, this work also provides scenarios that can be used to evaluate the ability of climate-carbon cycle models when they are pushed to the extreme scenarios of the geologic past.
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Climate
| 2,020 |
October 5, 2020
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https://www.sciencedaily.com/releases/2020/10/201005122145.htm
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Scientist maps CO2 emissions for entire US to improve environmental policymaking
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With intense wildfires in the western U.S. and frequent, intense hurricanes in the Gulf of Mexico, the nation is again affected by extreme weather-related events resulting from climate change. In response, cities, states and regions across the country are developing policies to reduce their emissions of greenhouse gases, chiefly carbon dioxide (CO
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Professor Kevin Gurney of Northern Arizona University's School of Informatics, Computing, and Cyber Systems today published results in the Gurney, who specializes in atmospheric science, ecology and public policy, has spent the past several years developing a standardized system, as part of the Vulcan Project, that quantifies and visualizes greenhouse gases emitted across the entire country down to individual power plants, neighborhoods and roadways, identifying problem areas and enabling better decisions about where to cut emissions most effectively. Leading up to the nationwide study, Gurney produced emissions maps of several different large cities, including the Los Angeles megacity, Indianapolis, the Washington, D.C./Baltimore metropolitan area and Salt Lake City.Funded by NASA, Gurney developed the high-resolution emissions map as an effective tool for scientific and policy applications. His goal is to provide policymakers across the nation with a means to strategically address problem areas instead of taking an inefficient, costly approach."We're providing U.S. policymakers at national, state and local scales with a scalpel instead of a hammer. Policies that might be relevant to California are possibly less relevant for Chicago or New York. They need to have information that reflects their unique conditions but follows a rigorous, standardized scientific approach. In this way, they can have confidence in the numbers which, in turn, will stimulate smart investment in reducing emissions."One of the strengths of Gurney's approach is validation by atmospheric monitoring of CO"By synthesizing the detail of building and road-scale emissions with the independence and accuracy of atmospheric monitoring," Gurney said, "we have the best possible estimate of emissions with the most policy-relevant detail."An animated video of the Vulcan Project output is available online.Through characterization of CO
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Climate
| 2,020 |
October 5, 2020
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https://www.sciencedaily.com/releases/2020/10/201005112141.htm
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Two's a crowd: Nuclear and renewables don't mix
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If countries want to lower emissions as substantially, rapidly and cost-effectively as possible, they should prioritize support for renewables, rather than nuclear power.
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That's the finding of new analysis of 123 countries over 25 years by the University of Sussex Business School and the ISM International School of Management which reveals that nuclear energy programmes around the world tend not to deliver sufficient carbon emission reductions and so should not be considered an effective low carbon energy source.Researchers found that unlike renewables, countries around the world with larger scale national nuclear attachments do not tend to show significantly lower carbon emissions -- and in poorer countries nuclear programmes actually tend to associate with relatively higher emissions.Published today in Benjmin K Sovacool, Professor of Energy Policy in the Science Policy Research Unit (SPRU) at the University of Sussex Business School, said: "The evidence clearly points to nuclear being the least effective of the two broad carbon emissions abatement strategies, and coupled with its tendency not to co-exist well with its renewable alternative, this raises serious doubts about the wisdom of prioritising investment in nuclear over renewable energy. Countries planning large-scale investments in new nuclear power are risking suppression of greater climate benefits from alternative renewable energy investments."The researchers, using World Bank and International Energy Agency data covering 1990-2014, found that nuclear and renewables tend to exhibit lock-ins and path dependencies that crowd each other out, identifying a number of ways in which a combined nuclear and renewable energy mix is incompatible.These include the configuration of electricity transmission and distribution systems where a grid structure optimized for larger scale centralized power production such as conventional nuclear, will make it more challenging, time-consuming and costly to introduce small-scale distributed renewable power.Similarly, finance markets, regulatory institutions and employment practices structured around large-scale, base-load, long-lead time construction projects for centralized thermal generating plant are not well designed to also facilitate a multiplicity of much smaller short-term distributed initiatives.Andy Stirling, Professor of Science and Technology Policy at the University of Sussex Business School, said: "This paper exposes the irrationality of arguing for nuclear investment based on a 'do everything' argument. Our findings show not only that nuclear investments around the world tend on balance to be less effective than renewable investments at carbon emissions mitigation, but that tensions between these two strategies can further erode the effectiveness of averting climate disruption."The study found that in countries with a high GDP per capita, nuclear electricity production does associate with a small drop in COAnd in countries with a low GDP per capita, nuclear electricity production clearly associates with COPatrick Schmid, from the ISM International School of Management München, said: "While it is important to acknowledge the correlative nature of our data analysis, it is astonishing how clear and consistent the results are across different time frames and country sets. In certain large country samples the relationship between renewable electricity and CO
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Climate
| 2,020 |
October 5, 2020
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https://www.sciencedaily.com/releases/2020/10/201005112135.htm
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World's largest collection of moss species
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Peatlands with their huge diversity of peat moss species store about 30 percent of the earth's soil carbon. This means they store roughly twice as much carbon as all the world's forests combined. However, peat harvesting and climate change are threatening these long-term carbon stores because there is not enough founder material for cultivating peat mosses on a large scale. In collaboration with researchers from the University of Greifswald, a team of scientists led by plant biotechnologist Professor Ralf Reski from the Faculty of Biology of the University of Freiburg in Germany has established the world's largest laboratory collection of mosses of the genus Sphagnum. With this as a foundation, peat mosses can be grown in a sustainable and economic way. The scientists have published their research in the scientific journal
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For their project -- called MOOSzucht -- the scientists collected sporophytes, the spore capsules of mosses, of 19 Sphagnum species in Austria, Germany, Latvia, Russia, Sweden, and the Netherlands. The world's largest collection of Sphagnum cultures is now housed in the International Moss Stock Center (IMSC), a resource center founded in 2010 at the University of Freiburg. Scientists use the spores to create pure peat moss cultures in a laboratory environment that are not contaminated by bacteria, fungi, algae, or suchlike. Some species grow at a rate 50 to 100 times faster in the laboratory than in a moor landscape. The researchers measured the growth of the mosses in liquid mediums containing nutrients, also known as suspension cultures. They also determined how many sets of chromosomes could be found in the cell nuclei in the cultures and compared this to the genome size of the already established model moss Physcomitrella patens. In this way they were able to identify haploid and diploid Sphagnum species -- in other words, species with single or double sets of chromosomes, respectively. However, they could not find a correlation between the number of sets of chromosomes and moss growth, meaning it is still unclear why diploid mosses exist in nature.Peat is harvested on a large scale for growing vegetables and ornamental plants in greenhouses and home gardens. Due to climate change and the resulting droughts and higher temperatures, peat mosses are showing poorer growth, deteriorating more quickly, and binding less carbon. The researchers from the University of Freiburg want to replace this dire need for peat with renewable biomass. However, the large amount of founder material that would be needed for this can only be produced in bioreactors. That is why Reski and his team at the IMSC are distributing lab strains of peat mosses to various research institutes and companies who are active in basic research, biotechnology, or in sustainable bioeconomy.
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Climate
| 2,020 |
October 5, 2020
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https://www.sciencedaily.com/releases/2020/10/201005080859.htm
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40 percent of Amazon could now exist as rainforest or savanna-like ecosystems
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A larger part of the Amazon rainforest is at risk of crossing a tipping point where it could become a savanna-type ecosystem than previously thought, according to new research. The research, based on computer models and data analysis, is published in the journal
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Rainforests are very sensitive to changes that affect rainfall for extended periods. If rainfall drops below a certain threshold, areas may shift into a savanna state."In around 40 percent of the Amazon, the rainfall is now at a level where the forest could exist in either state -- rainforest or savanna, according to our findings," says lead author Arie Staal, formerly a postdoctoral researcher at the Stockholm Resilience Centre and the Copernicus Institute of Utrecht University.The conclusions are concerning because parts of the Amazon region are currently receiving less rain than previously and this trend is expected to worsen as the region warms due to rising greenhouse gas emissions.Staal and colleagues focused on the stability of tropical rainforests in the Americas, Africa, Asia and Oceania. With their approach they were able to explore how rainforests respond to changing rainfall."By using the latest available atmospheric data and teleconnection models, we were able to simulate the downwind effects of disappearance of forests for all tropical forests. By integrating these analyses over the entire tropics, the picture of the systematic stability of tropical forests emerged," says Obbe Tuinenburg, former assistant professor at the Copernicus Institute of Utrecht University and visiting scientist at the Stockholm Resilience Centre.The team explored the resilience of tropical rainforests by looking at two questions: what if all the forests in the tropics disappeared, where would they grow back? And its inverse: what happens if rainforests covered the entire tropical region of Earth?Such extreme scenarios could inform scientists about the resilience and stability of real tropical forests. They can also help us understand how forests will respond to the changing rainfall patterns as greenhouse gases in the atmosphere rise.The researchers ran the simulations starting with no forests in the tropics across Africa, the Americas, Asia and Australia. They watched forests emerge over time in the models. This allowed them to explore the minimum forest cover for all regions.Staal said, "The dynamics of tropical forests is interesting. As forests grow and spread across a region this affects rainfall -- forests create their own rain because leaves give off water vapour and this falls as rain further downwind. Rainfall means fewer fires leading to even more forests. Our simulations capture this dynamic."The team ran the models a second time, this time in a world where rainforests entirely covered the tropical regions of Earth. This is an unstable scenario because in many places there is not enough rainfall to sustain a rainforest. In many places the forests shrank back due to lack of moisture.Staal says, "As forests shrink, we get less rainfall downwind and this causes drying leading to more fire and forest loss: a vicious cycle."Finally the researchers explored what happens if emissions keep rising this century along a very high-emissions scenario used by the Intergovernmental Panel on Climate Change (IPCC).Overall, the researchers found that as emissions grow, more parts of the Amazon lose their natural resilience, become unstable and more likely to dry out and switch to become a savanna-type ecosystem. They note that even the most resilient part of the rainforest shrinks in area. In other words, more of the rainforest is prone to crossing a tipping point as emissions of greenhouse gases reach very high levels."If we removed all the trees in the Amazon in a high-emissions scenario a much smaller area would grow back than would be the case in the current climate," says co-author Lan Wang-Erlandsson of the Stockholm Resilience Centre.The researchers conclude that the smallest area that can sustain a rainforest in the Amazon contracts a substantial 66% in the high-emissions scenario.In the Congo basin the team found that the forest remains at risk of changing state everywhere and will not grow back once gone, but that under a high emissions scenario part of the forest becomes less prone to crossing a tipping point. But Wang-Erlandsson adds 'This area where natural forest regrowth is possible remains relatively small.""We understand now that rainforests on all continents are very sensitive to global change and can rapidly lose their ability to adapt," says Ingo Fetzer of the Stockholm Resilience Centre. "Once gone, their recovery will take many decades to return to their original state. And given that rainforests host the majority of all global species, all this will be forever lost."The academics found that the minimal and maximal extents of the rainforests of Indonesia and Malaysia are relatively stable because their rainfall is more dependent on the ocean around them than on rainfall generated as a result of forest cover.The study only explored the impacts of climate change on tropical forests. It did not assess the additional stress of deforestation in the tropics due to agricultural expansion and logging.
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Climate
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October 2, 2020
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https://www.sciencedaily.com/releases/2020/10/201002122103.htm
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Future climate changes in nature reserves
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The Earth's nature reserves are the basis for the preservation of global biodiversity. They are set to be affected by future climate change in very different ways. Detailed local knowledge of climate change impacts can therefore make a significant contribution to the management of protected areas and the preservation of their ecological function. A biogeographic study by the University of Bayreuth in the journal "
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For their new study, Prof. Dr. Carl Beierkuhnlein and Dr. Samuel Hoffmann of the Biogeography research group examined a total of 137,735 nature reserves on six continents. Their focus was on the question of what deviations from current climate conditions these areas will be exposed to over the next five decades, and how this will impact local plant and animal species. "Blanket forecasts on climate change are not specific enough to assist in counteracting the threat of further loss of biodiversity. This can only succeed if we know exactly what local climate change -- for example in nature reserves -- will be caused by global trends. As our study impressively demonstrates, these local effects can be very different, even in neighbouring areas," says Beierkuhnlein.Particularly severe local climate changes are expected by 2070, especially in protected areas of tropical countries. Today, these are of great importance for the conservation of globally endangered plant and animal species, and are under great pressure because, at the same time, they are being used intensively by humans. These protected areas are located in mountains high above sea level. In mountains, temperatures are expected to rise noticeably as a result of climate change. Consequently, some endangered species will probably try to migrate to higher and therefore cooler mountain regions. Here, the threat to individual species could increase rapidly because fewer resources are available at higher altitudes. "For migratory species, higher mountain regions could prove to be a dead end," Hoffmann explains.However, the new study also shows that protected areas in which future climate conditions will differ especially from the present have some characteristics that could have a beneficial effect on the conservation of species. They are often very large, have very different landscape profiles, and therefore offer diverse environmental conditions which are little affected by direct human intervention or fragmented by traffic routes. These circumstances favour the adaptation of species, for example through genetic exchange and greater availability of resources. In addition, some species that are forced to leave their current habitats due to climate change may find new habitats in their very neighbourhood thanks to this diversity of landscape. Hence, management that is well informed about local climate changes can help to mitigate the effects of climate change in nature reserves.Forecasts of global climate change are always fraught with uncertainty. This is why the Bayreuth researchers worked with ten different global models of climate change in their study of nature reserves. In addition, they included two significantly different scenarios of global greenhouse gas emissions in their assessments. In each of the nature reserves studied, small square areas measuring around one square kilometre were examined. Characteristic properties of these "cells" were then put into relation with climatic change to be expected on a global scale by 2070. These characteristics include, for example, height above sea level, landscape profile, precipitation and temperature, local flora and fauna, and human intervention. With these investigations, the Bayreuth researchers have succeeded in estimating local climate change effects for very small areas worldwide.
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Climate
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October 2, 2020
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https://www.sciencedaily.com/releases/2020/10/201002105743.htm
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Climate change responsible for record sea temperature levels
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Global warming is driving an unprecedented rise in sea temperatures including in the Mediterranean, according to a major new report published by the peer-reviewed
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Data from the European Union's (EU) Copernicus Marine Environment Monitoring Service (CMEMS) will increase concerns about the threat to the world's seas and oceans from climate change.The Ocean State Report reveals an overall trend globally of surface warming based on evidence from 1993 to 2018, with the largest rise in the Arctic Ocean.European seas experienced record high temperatures in 2018, a phenomenon which the researchers attribute to extreme weather conditions -- a marine heat wave lasting several months.In the same year, a large mass of warm water occurred in the northeast Pacific Ocean, according to the report. This was similar to a marine heatwave -- dubbed 'the Blob' -- which was first detected in 2013 and had devastating effects on marine life.Now the study authors are calling for improved monitoring to provide better data and knowledge. They argue this will help countries progress towards sustainable use of seas and oceans which are an essential source of food, energy and other resources."Changes to the ocean have impacted on these (ocean) ecosystem services and stretched them to unsustainable limits," says Karina von Schuckmann and Pierre-Yves Le Traon, the report's editors."More than ever a long term, comprehensive and systematic monitoring, assessment and reporting of the ocean is required. This is to ensure a sustainable science-based management of the ocean for societal benefit."The Ocean State Report identifies other major strains on the world's seas and oceans from climate change including acidification caused by carbon dioxide uptake from the atmosphere, sea level rise, loss of oxygen and sea ice retreat.Long-term evidence of global warming outlined in the report includes a decrease over 30 years of up to two days in the period of Baltic Sea ice cover and an acceleration in the global mean sea level rise.The report highlights that the message from recent EU and global assessments of the state of seas and oceans is 'we are not doing well'. The authors add: "Human society has always been dependent on the seas. Failure to reach good environmental status for our seas and oceans is not an option."
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Climate
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October 2, 2020
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https://www.sciencedaily.com/releases/2020/10/201002091055.htm
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Coastal flooding will disproportionately impact 31 million people globally
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Thirty-one million people living in river deltas are at high risk of experiencing flooding and other impacts from tropical cyclones and climate change, according to a study by Indiana University researchers.
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"To date, no one has successfully quantified the global population on river deltas and assessed the cumulative impacts from climate change," said Douglas Edmonds, the Malcolm and Sylvia Boyce Chair in the Department of Earth and Atmospheric Sciences and lead author on the study. "Since river deltas have long been recognized as hotspots of population growth, and with increasing impacts from climate change, we realized we needed to properly quantify what the cumulative risks are in river deltas."The findings are the result of a collaboration facilitated by IU's Institute for Advanced Study with support from the Environmental Resilience Institute.The team's analysis shows that river deltas occupy 0.5 percent of the earth's land surface, yet they contain 4.5 percent of the global population -- a total of 339 million people. Because river deltas form at the ocean at or below sea level, they are highly prone to storm surges, which are expected to occur more frequently due to climate change-fueled sea-level rise and coastal flooding.In the study, IU researchers analyzed these geographic regions, which include cities like New Orleans, Bangkok, and Shanghai, using a new global dataset to determine how many people live on river deltas, how many are vulnerable to a 100-year storm surge event, and the ability of the deltas to naturally mitigate impacts of climate change."River deltas present special challenges for predicting coastal floods that deserve more attention in discussions about the future impacts of climate change," said IU Distinguished Professor of Anthropology Eduardo Brondizio, a co-author of the study who has been working with rural and urban communities in the Amazon delta for 3 decades. "Our estimates are likely a minimum because the storm surge and flooding models do not account for the compound interactions of the climate impacts, deficient infrastructure, and high population density."With Edmonds and Brondizio, co-authors on the study include Rebecca Caldwell and graduate student Sacha Siani.In addition to the threat of flooding, many of the residents in river deltas are low-income and experience water, soil, and air pollution, poor and subnormal housing infrastructure, and limited access to public services. According to the study, of the 339 million people living on deltas throughout the world, 31 million of these people are living in the 100-year storm surge floodplains. To make matters worse, 92 percent of the 31 million live in developing or least-developed economies. As a result, some of the most disadvantaged populations are among the most at-risk to the impacts of climate change."These communities are already dealing with health risks, lack of sanitation and services, poverty, and exposure to flooding and other environmental risks. Climate change is exacerbating all of these issues and creating more impacts," Brondizio said.To conduct their study, the researchers created a global dataset of delta populations and areas, aggregating 2,174 delta locations. They then cross-referenced the dataset with a land population count to determine how many people were living in the deltas. To determine the natural mitigation capacity of the deltas, researchers looked at the volume of incoming sediment deposited by rivers and other waterways flowing out to sea. The volume of incoming sediment was compared to the relative area of the delta to determine if the delta would be considered sediment starved and thus unable to naturally mitigate flooding.Decades of engineering have expanded the habitable land area of river deltas, but they've also starved the regions of flood-preventing sediment. Without the sediment being renewed naturally, the shorelines will continue to recede, worsening the impacts of storm surges"To effectively prepare for more intense future coastal flooding, we need to reframe it as a problem that disproportionately impacts people on river deltas in developing and least-developed economies," said Edmonds. "We need better models for the climate impacts that are capable of stimulating compound flooding in densely populated areas so that exposure and risk can be mapped to more accurately assess risk and vulnerability."
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Climate
| 2,020 |
October 1, 2020
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https://www.sciencedaily.com/releases/2020/10/201001155908.htm
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Ice discharge in the North Pacific set off series of climate events during last ice age
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Repeated catastrophic ice discharges from western North America into the North Pacific contributed to, and perhaps triggered, hemispheric-scale changes in the Earth's climate during the last ice age, new research published online today in
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The discovery provides new insight into the impact rapidly melting ice flowing into the North Pacific may have on the climate across the planet, said Maureen Walczak, a paleoclimatologist in Oregon State University's College of Earth, Ocean, and Atmospheric Sciences and the study's lead author."Understanding how the ocean has interacted with glacial ice in the past helps us predict what could happen next," Walczak said.The Cordilleran ice sheet once covered large portions of western North America from Alaska to Washington state and western Montana. Radiocarbon dating and analyses of the marine sediment record revealed that recurrent episodes of discharge from this ice sheet over the past 42,000 years were early events in a chain reaction of disturbances to the global climate. These disturbances triggered changes in deep ocean circulation and retreat of ice sheets in the North Atlantic.The findings challenge theories that those massive, globally-reaching disturbances originated in the North Atlantic as rapid ice loss from the Laurentide ice sheet, another massive ice sheet that covered much of Canada and the northern United States, including the upper Midwest and Northeast. The Laurentide ice loss events are known as Heinrich Events."The outcome of this research was unexpected. The data irrevocably says that the Pacific ice goes first, with Heinrich Events and other changes following in a rhythm. The Pacific Ocean sets the drum beat," Walczak said. "This is a paradigm shift in our thinking about how these events are connected."To gain insight into the climate history of the North Pacific, an international team of researchers collected and analyzed sediment cores from the northern Gulf of Alaska that were recovered by drilling as part of the International Ocean Discovery Program."Getting these new insights took years of work. We first mapped the seafloor and recovered short sediment cores in 2004, drilled longer cores in 2013 and had 16 years of painstaking laboratory work involving several Ph.D. students," said Alan Mix, the project's principal investigator and co-author of the paper."This was a virtually unknown area when we started, and now it offers among the most detailed and best-dated long records of ocean change on the planet during the ice age," said Mix, a distinguished professor in OSU's College of Earth, Ocean, and Atmospheric Sciences.Researchers measured radioactive isotopes of carbon using two particle accelerators to establish the chronology of events and also added meticulous counts of small rocks dropped by icebergs known as ice-rafted debris.The research team traced the source of the ice-rafted debris back to purges of massive ice streams emanating from the Cordilleran ice sheet, which covered northern Washington, most of British Columbia and southern Alaska from about 70,000 to 17,000 years ago.Dirty icebergs broke off from surging ice streams and drifted northward in ocean currents, carrying and eventually dropping their load of sand, pebbles and gravel, leaving a record of rapid ice retreat buried in the deep sea like sunken treasure.The authors of the study named these Alaskan iceberg dumps "Siku Events" after the Inuit word for ice. The big surprise, discovered by combining the record of glacial debris with the radiocarbon chronology, was that Siku Events immediately preceded Heinrich events, which are a similar type of ice purge in the North Atlantic.Scientists have been aware of Heinrich Events, from similar evidence of ice-rafted debris in the North Atlantic, for more than 30 years but the trigger for those events has never been convincingly explained, the researchers said.It makes sense for the Pacific Ocean to be involved in major planetary changes, Mix said. The Pacific Ocean is connected to the rest of the world by large-scale atmospheric circulation and physically around Antarctica, and during times of high sea level, through the Bering Strait and the Arctic Ocean to the North Atlantic."The Pacific Ocean is the largest exchangeable reservoir of heat and water and carbon dioxide on Earth, simply because of its massive size," he said. "It really is the 800-pound gorilla in the zoo of climate beasts."Today the ice that remains along the coast of Alaska is mostly retreating and may be gone within this century as the climate warms. The melting ice will drain to the Pacific and the Arctic, contributing to sea level rise and impacting the balance of buoyant fresh and dense salty water in the ocean, much as it did in the past.If the current ice melt follows patterns of the past, and happens quickly, it could contribute to the retreat of distant glacial systems in the North Atlantic and the Arctic."This is yet another reason that it is prudent to slow down warming by reducing our fossil-fuel use," Mix said."The new findings are likely to fuel increased interest in the North Pacific, an area that has not been as well-studied as other parts of the planet," Walczak said.One thing that remains unclear is why the discharges from the Cordilleran ice sheet occurred. Researchers also would like to better understand the relationship between the discharges of the Cordilleran and the other climate events."Why did the other ice sheets respond to the retreat of the Cordilleran? How fast do the dominoes fall in this sequence of events?" Walczak asked. Those are among the questions the research team is continuing to investigate.The research was supported by the National Science Foundation, the Australian Research Council, the Australian-New Zealand IODP Commission and the American Australian Association.
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Climate
| 2,020 |
October 1, 2020
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https://www.sciencedaily.com/releases/2020/10/201001113622.htm
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Scientists repeat century-old study to reveal evidence of evolutionary rescue in the wild
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A tiny flatworm found commonly on the coasts of western Europe and North America is living proof that species may be able to evolve and adapt to rapid climate change.
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Research by the University of Plymouth examined the extent to which the intertidal flatworm Repeating a study conducted more than a century earlier it was shown that the response of individuals had changed markedly since then.The original study was conducted by Dorothy Jordan Lloyd, who was based at the Marine Biological Association in Plymouth, and focussed on individuals found in Wembury Bay, Plymouth.It was published in 1914, and the current study -- led by BSc (Hons) Marine Biology graduate Katharine Clayton -- replicated it in terms of the processes followed and the precise locations from which samples were collected.When tested across a range of different concentrations of salt water in the laboratory, scientists showed the flatworm was able to regenerate following minor injuries at lower salinities than were recorded originally.They also demonstrated that while in 1914 there was an optimum salinity level for individuals to regenerate this is no longer the case, suggesting individuals have extended their tolerance range in the intervening 104 years.Scientists also examined rainfall levels for the Wembury Bay area and found they had increased between 1914 and 2018, which is likely to result in exposure to lower salinities in the intertidal region, where the flatworm is found.Put together, they say it shows how individual species may be able to adapt and survive the localised effects of climate change which, if correct, provides some of the first evidence of evolutionary rescue taking place in the wild.Katharine Clayton began the study as part of her undergraduate degree and wrote it up for her final year dissertation. Now pursuing a PhD at the University of Exeter, she said: "When we first began looking at this flatworm, we were interested in how it tolerated salinity levels in it natural habitat. However, we quickly found out about Dorothy's study in 1914 so it became a perfect test of how an individual population had adapted to changes within its immediate environment. The findings provide really interesting evidence of the impacts of climate change, but it has also been inspiring for me to revisit Dorothy's work and highlight a pioneering female scientist of her time."The research's co-author, Professor of Marine Zoology John Spicer, supervised Katharine's work and is an authority on how marine species can adapt to climate change. He added: "There has been an idea around for the last 15 to 20 years called evolutionary rescue where, faced with rapid climate change, animals evolve to survive. Many, including myself, have doubted the possibility of such rescue, especially over such a short space of time in terms of species evolution. But this study shows it may well be possible in the wild because, in comparing two identical experiments 100 years apart, the animal has changed how it works, its physiology."It is proof that evolutionary rescue may exist in the wild, not just in the laboratory, and is a major step forward in our understanding of how species can adapt as the environment around them changes. With the two studies being conducted 50 years before and after the start of the Anthropocene, it also provides a fascinating insight into the effect humans are having on species with whom we share our planet."
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Climate
| 2,020 |
October 1, 2020
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https://www.sciencedaily.com/releases/2020/10/201001113557.htm
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Decent living for all does not have to cost the Earth
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Global energy consumption in 2050 could be reduced to the levels of the 1960s and still provide a decent standard of living for a population three times larger, according to a new study.
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The study led by the University of Leeds has estimated the energy resource needed for everyone to be provided decent living standards in 2050 -- meaning all their basic human needs such as shelter, mobility, food and hygiene are met, while also having access to modern, high quality healthcare, education and information technology.The findings, published in in the journal This level of global energy consumption is roughly the same as that during the 1960s, when the population was only three billion.The authors emphasise that achieving this would require sweeping changes in current consumption, widespread deployment of advanced technologies, and the elimination of mass global inequalities.However, not only do the findings show that the energy required to provide a decent living could likely be met entirely by clean sources, but it also offers a firm rebuttal to reactive claims that reducing global consumption to sustainable levels requires an end to modern comforts and a 'return to the dark ages'.The authors' tongue in cheek response to the critique that sweeping energy reform would require us all to become 'cave dwellers' was: "Yes, perhaps, but these are rather luxurious caves with highly-efficient facilities for cooking, storing food and washing clothes; comfortable temperatures maintained throughout the year, computer networks -- among other things -- not to mention the larger caves providing universal healthcare and education to all 5-19 year olds."The study calculated minimum final energy requirements, both direct and indirect, to provide decent living standards. Final energy is that delivered to the consumer's door, for example, heating, electricity or the petrol that goes into a car, rather than the energy embedded in fuels themselves -- much of which is lost at power stations in the case of fossil fuels.The team built a final energy-model, which builds upon a list of basic material needs that underpin human well-being previously developed by Narasimha Rao and Jihoon Min.The study compared current final energy consumption across 119 countries to the estimates of final energy needed for decent living and found the vast majority of countries are living in significant surplus. In countries that are today's highest per-capita consumers, energy cuts of nearly 95% are possible while still providing decent living standards to all.Study lead author Dr Joel Millward-Hopkins from the School of Earth and Environment at Leeds said: "Currently, only 17% of global final energy consumption is from non-fossil fuel sources. But that is nearly 50% of what we estimate is needed to provide a decent standard of living for all in 2050.""Overall, our study is consistent with the long-standing arguments that the technological solutions already exist to support reducing energy consumption to a sustainable level. What we add is that the material sacrifices needed to for these reductions are far smaller than many popular narratives imply."Study co-author Professor Julia Steinberger leader of the Living Well Within Limits project at the University Leeds and professor at the Université de Lausanne in Switzerland said: "While government official are levelling charges that environmental activists 'threaten our way of life' it is worth re-examining what that way of life should entail. There has been a tendency to simplify the idea of a good life into the notion that more is better."It is clearly within our grasp to provide a decent life for everyone while still protecting our climate and ecosystems."Study co-author Professor Narasimha Rao from Yale University said: "This study also confirms our earlier findings at a global scale that eradicating poverty is not an impediment to climate stabilization, rather it's the pursuit of unmitigated affluence across the world."Study co-author Yannick Oswald, PhD researcher at the School of Earth and Environment at Leeds said: "To avoid ecological collapse, it is clear that drastic and challenging societal transformations must occur at all levels, from the individual to institutional, and from supply through to demand."
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Climate
| 2,020 |
October 1, 2020
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https://www.sciencedaily.com/releases/2020/10/201001090145.htm
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Climate: Iodic acid influences cloud formation at the North Pole
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The Arctic is warming two or three times faster than the rest of the planet. This amplified warming is due to several factors, but the relative importance of each one remains still unclear. "We do know, however, that clouds could play an important role," says Julia Schmale, an EPFL professor who heads the Extreme Environments Research Laboratory and holds the Ingvar Kamprad Chair. "By reflecting the sun's rays back into space or trapping heat close to the Earth's surface like a blanket, clouds help either cool off or warm up the planet."
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Schmale -- along with scientists from the Paul Scherrer Institute's Laboratory of Atmospheric Chemistry and Stockholm University's Department of Environmental Science and Bolin Centre for Climate Research -- spent several weeks collecting data near the North pole in August and September 2018, as part of the US-Swedish expedition Arctic Ocean 2018 on board the Swedish icebreaker Oden. The scientists measured the chemical and physical properties of atmospheric molecules and aerosol particles to better understand the conditions leading to cloud formation."One of our objectives was to investigate how new aerosol particles could form in the Arctic atmosphere," says Andrea Baccarini, a PhD student at the Paul Scherrer Institute and now scientific collaborator in the extreme Environments research Laboratory. "Under the right conditions, gas molecules condense together into small clusters that can grow, eventually forming aerosols." If these aerosols grow even just a small amount larger, they can function as cloud condensation nuclei, which are essential for cloud formation.In the Arctic summer and fall, the concentration of aerosols is extremely low. "The contribution of newly formed aerosols can be extremely important and even a small change in aerosol concentration in the high Arctic could have a major impact on cloud formation or alter clouds' radiative properties," says Baccarini. It is also still not clear how important local aerosol processes are to cloud formation in comparison to regional or long-range transport, for example. "With this expedition, we could investigate the exact sources of aerosol particles that are needed to form clouds" adds Paul Zieger, an assistant professor at Stockholm University who led the research project on aerosol-cloud processes of the 2018 expedition.The research team found that iodic acid, a chemical compound which had not previously been observed in the region, triggers the formation of new aerosols between late summer and early fall. "There is less ice in the Arctic at the end of the summer, a lot of open water and the concentration of iodic acid is very low at that point," says Schmale. "Towards the end of August the temperature drops and the water starts refreezing, marking the beginning of the so called freeze-up period. This is when the iodic acid concentration sharply increases leading to frequent new aerosol particle formation events''.The team developed a simple model to explain the variability of iodic acid in the atmosphere, which largely depends on local meteorological conditions. They were also able to describe the full chain of events that leads all the way from new particle formation to clouds, from the gas molecule that initially creates a particle to the formation of cloud condensation nuclei. "Observing and describing this process under real-world conditions was an extremely rare opportunity," says Schmale.
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Climate
| 2,020 |
October 1, 2020
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https://www.sciencedaily.com/releases/2020/10/201001090143.htm
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Alien species to increase by 36% worldwide by 2050
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The number of alien (non-native) species, particularly insects, arthropods and birds, is expected to increase globally by 36% by the middle of this century, compared to 2005, finds new research by an international team involving UCL.
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Published in The research team led by the German Senckenberg Biodiversity and Climate Research Centre hope it should be possible to reduce this number with stricter biosecurity regulations.Alien species are those that humans have moved around the world to places where they do not naturally occur. More than 35,000 such species had been recorded by 2005 (the date of the most recent comprehensive global catalogue). Some of these aliens can go on to become invasive, with damaging impacts to ecosystems and economies. Alien species are one of the main drivers of extinctions of animals and plants.Co-author Professor Tim Blackburn (UCL Centre for Biodiversity & Environment Research and the Institute of Zoology, ZSL) said: "Our study predicts that alien species will continue to be added to ecosystems at high rates through the next few decades, which is concerning as this could contribute to harmful biodiversity change and extinction."But we are not helpless bystanders: with a concerted global effort to combat this, it should be possible to slow down or reverse this trend."For the study, the research team developed a mathematical model to calculate for the first time how many more aliens would be expected by 2050, based on estimated sizes of source pools (the species that could end up becoming invasive) and dynamics of historical invasions, under a 'business-as-usual' scenario that assumes a continuation of current trends.The model predicts a 36% increase in the number of alien plant and animal species worldwide by 2050, compared to 2005 levels.The study identifies high levels of variation between regions. The largest increase is expected in Europe, where the number of alien species will increase by 64% by the middle of the century. Additional alien hotspots are predicted to include temperate latitudes of Asia, North America, and South America. The lowest relative increase in alien species is expected in Australia.Europe will also see the largest increase in absolute numbers of alien species, with around 2,500 new aliens predicted.Lead author Dr Hanno Seebens (Senckenberg Biodiversity and Climate Research Centre, Germany) said: "These will primarily include rather inconspicuous new arrivals such as insects, molluscs, and crustaceans. In contrast, there will be very few new alien mammal species such as the well-known raccoon."Co-author Dr Franz Essl (University of Vienna) added: "Increases are expected to be particularly large for insects and other arthropods, such as arachnids and crustaceans. We predict the number of aliens from these groups to increase in every region of the world by the middle of the century -- by almost 120% in the temperate latitudes of Asia."The study also predicts that the rate of arrival of alien species will continue to increase, at least in some animal groups. Globally, by 2050, alien arthropod and bird species in particular will arrive faster than before, compared to the period 1960 -- 2005. In Europe, the rate of new alien arrivals is expected to increase for all plant and animal groups except mammals.Neither a reversal nor even a slowdown in the spread of alien species is in sight, as global trade and transport are expected to increase in the coming decades, allowing many species to infiltrate new habitats as stowaways.Dr Seebens said: "We will not be able to entirely prevent the introduction of alien species, as this would mean severe restrictions in international trade."However, stricter regulations and their rigorous enforcement could greatly slow the flow of new species. The benefits of such measures have been shown in some parts of the world. Regulations are still comparatively lax in Europe, and so there is great potential here for new measures to curtail the arrival of new aliens."
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Climate
| 2,020 |
October 1, 2020
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https://www.sciencedaily.com/releases/2020/10/201001113646.htm
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Satellite imaging to map groundwater use in California's central valley
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Researchers at the University of California San Diego report in a new study a way to improve groundwater monitoring by using a remote sensing technology (known as InSAR), in conjunction with climate and land cover data, to bridge gaps in the understanding of sustainable groundwater in California's San Joaquin Valley.
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Their work could be revolutionary for managing groundwater use in agricultural regions around the world, as groundwater monitoring and management have been notoriously difficult to carry out due to lack of reliable data.The satellite-based InSAR (interferometric synthetic aperture radar) is used to make high-resolution maps of land surface motion in space and time, including measurement of subsidence (or sinking). Subsidence can occur when large amounts of groundwater are removed from underground stores, called aquifers.The study, published in the journal Environmental Research Letters, took advantage of the incredibly fine-scale resolution of InSAR to evaluate subsidence patterns according to crop type, revealing surprising results. For example, despite reports of high water consumption by fruit and nut crops in California, the crop types with the greatest rates of subsidence, and by association the greatest rates of groundwater use, were field crops such as corn and soy, followed by pasture crops like alfalfa, truck crops like tomatoes, and lastly, fruit and nut crops like almonds and grapes."Our initial hypothesis was that fruit and nut crops would be associated with some of the highest rates of subsidence, but we found the opposite," said study lead author, Morgan Levy, an assistant professor with a joint appointment with UC San Diego's Scripps Institution of Oceanography and School of Global Policy and Strategy.Because displacement is a response to groundwater storage change in locations with varying geology, soils and vegetation, the interpretation of InSAR varies across locations, unlike satellite measurements of climate that have the same interpretation in any location. Therefore, InSAR must be combined with other sources of geophysical data to achieve location-specific insight into groundwater use.By combining InSAR with other land surface datasets including land cover, potential evapotranspiration (a measure of plant water demand), and the location of surface water supply networks, UC San Diego researchers found that between 2015 and 2017, subsidence occurred at much higher rates in irrigated cultivated land compared to undeveloped land, and in dry surface water-limited years relative to wet years.Over the study period, there was a median 272 millimeters (or 16 inches) of total cumulative subsidence for field crops (like corn and soy), and a dry water year subsidence rate of 131 millimeters (5 inches) per year. For fruit and nut crops, (like almonds and grapes) there was a median 62 millimeters (2.5 inches) of total subsidence over the study period, and a dry water year subsidence rate of 31 millimeters (1 inch) per year."The outcome might be explained by two things. First, on average fruits and nuts require less water physiologically, compared to field and pasture crops. Second, field and pasture crops tend to use irrigation methods that are less efficient and higher-volume than those used by fruit and nut crops," Levy said. "However, fruits and nuts may still consume greater total volumes of water because they occupy more land area, even if their groundwater use intensity is less."Methods and findings from this research could be used to support the state's ongoing effort to prevent overdraft of groundwater aquifers. Groundwater is a critical resource both nationally and globally: In the U.S., groundwater is a source of drinking water for roughly half of the population, and constitutes the largest source of irrigation water for agriculture. Irrigation accounts for approximately 70 percent of total U.S. groundwater withdrawals, and California has the highest rates of groundwater pumping in the nation."Our findings indicate that in the Central Valley, the costs and benefits of transitions away from field crops and towards fruit and nut crops in recent years are more complex than typically assumed," Levy added. "Our results suggest the possibility that transitions to fruit and nut cultivation might be desirable, at least from a groundwater sustainability perspective, although more research is needed to confirm this."California is an example of a semi-arid and irrigation-dependent climate for agriculture. Coordinated efforts from the UC San Diego team of climate scientists and geophysicists to link subsidence, groundwater and surface water use, and crop production data across comparable time and space scales has tremendous potential to advance groundwater monitoring and management in agricultural regions in other parts of the world, said the authors.In the San Joaquin Valley during wet years, farmers may receive up to 100 percent of their surface water allocations, while in extremely dry years, they may receive none. When surface water supplies are unavailable, farmers mine groundwater. Thus, groundwater has become increasingly important under climate change, as California and many parts of the world have experienced surface water shortages. However, excessive pumping does occur, even in relatively wet years. And, aquifers can run out.In 2014, California passed legislation mandating a gradual, locally led shift towards sustainable use of groundwater -- the resource on which 85 percent of its population and much of its $50-billon agriculture industry rely. The data from InSAR can be critical to the state's efforts to perform effective monitoring and management in response to climate change.While the legislation has encouraged local agencies to begin to use InSAR for documenting land subsidence, uses of InSAR for direct monitoring of groundwater use are early in their development. The UC San Diego research efforts provide an example of how water managers might use satellite data sources, including InSAR, to directly monitor local relationships between subsidence, groundwater pumping and crop portfolios."The promise of InSAR lies in our ability to combine it with other sources of geophysical and social data to answer water policy-relevant questions," Levy and co-authors wrote. "We provide a preview of the power of such a synthesis, demonstrating that spatial patterns of subsidence and their relationship to agricultural cultivation and associated water demand are clear and robust."They concluded, "Our findings suggest that policy levers supporting sustainable groundwater management might benefit from consideration of the groundwater use intensity of crop selection, not only the difficult-to-define sustainability of groundwater extraction volumes over groundwater aquifer boundaries that remain uncertain and that are costly to delineate."
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Climate
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September 30, 2020
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https://www.sciencedaily.com/releases/2020/09/200930194912.htm
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Nights warming faster than days across much of the planet
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Global warming is affecting daytime and night-time temperatures differently -- and greater night-time warming is more common than greater daytime warming worldwide -- new research shows.
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University of Exeter scientists studied warming from 1983 to 2017 and found a difference in mean annual temperature of more than 0.25°C between daytime and night-time warming in over half of the global land surface.Days warmed more quickly in some locations, and nights did in others -- but the total area of disproportionately greater night-time warming was more than twice as large.The study shows this "warming asymmetry" has been driven primarily by changing levels of cloud cover.Increased cloud cover cools the surface during the day and retains the warmth during the night, leading to greater night-time warming. Whereas, decreasing cloud cover allows more warmth to reach the surface during the day, but that warmth is lost at night."Warming asymmetry has potentially significant implications for the natural world," said lead author Dr Daniel Cox, of the Environment and Sustainability Institute on Exeter's Penryn Campus in Cornwall."We demonstrate that greater night-time warming is associated with the climate becoming wetter, and this has been shown to have important consequences for plant growth and how species, such as insects and mammals, interact."Conversely, we also show that greater daytime warming is associated with drier conditions, combined with greater levels of overall warming, which increases species vulnerability to heat stress and dehydration."Species that are only active at night or during the day will be particularly affected."The global study examined hourly records of temperature, cloud cover, specific humidity and precipitation.The authors modelled the different rates of change of daytime maximum and night-time minimum temperatures, and mean daytime and mean night-time cloud cover, specific humidity and precipitation.They then looked at changes in vegetation growth and precipitation over the same period.The study found that differences in daytime and night-time vegetation growth depended on rainfall.Increased night-time warming led to less vegetation growth where it rained more, likely due to increased cloud cover blocking the sun. Whereas, vegetation growth was limited by water availability due to less rainfall where the days warmed more.The research was funded in part by the Natural Environment Research Council.The paper, published in the journal
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Climate
| 2,020 |
September 30, 2020
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https://www.sciencedaily.com/releases/2020/09/200930144420.htm
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Rivers may begin jumping course much farther in the coming years
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A river's only consistent attribute is change. As the Greek philosopher Heraclitus remarked, "No man ever steps in the same river twice." Although this dynamic nature is often out of sight and mind, forgetting about it has led to many a historical catastrophe.
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Recently, UC Santa Barbara geomorphologist Vamsi Ganti and his collaborators published a study finding that sea level rise will cause rivers to jump course, or avulse, more often on deltas than in the past. Now his team has discovered that a perfect storm of factors -- including larger floods and finer sediment size -- will enable these destructive events to occur farther and farther inland. Their results, which appear in On large, relatively flat rivers, avulsions tend to occur in the backwater region, Ganti explained. "This is the zone over which the river flow feels the effect of the sea level." This region begins at the river mouth and can extend relatively far inland. For instance, the Mississippi River's backwater reach stretches 500 kilometers from the coast.The team was looking through satellite and remote sensing data for historical avulsions and came across the unique deltas of Madagascar. The island has a host of short rivers that course down from the mountains carrying very fine sediment. This is due to the saprolitic soils -- loose, soft soils made of silt and disintegrating rock -- that dominate the country's highlands. Exacerbated by rampant deforestation on the island, the exposed soils feed the island's turbid, red rivers and make it one of the fastest eroding places on Earth, according to lead author Sam Brooke, a postdoctoral scholar in the Department of Geography.Using multiple satellite images taken since the late 1970s, Brooke created time series animations that communicate just how fast Madagascar's river deltas are evolving. Using this data, he was able to obtain the rivers' discharge rates as well as the amount of time the channels remained full during floods.Combining the data with the satellite imagery led to a surprising conclusion. The avulsions weren't occurring anywhere near the rivers' backwater zones. "[Instead, they were] about 20 times [farther] upstream," Brooke recalled, "way outside of where we'd expect them to be based on [...models] using simple backwater scale." The researchers realized they had to update their models of where avulsions occur on deltas.A better modelThe team's expanded theory boils down to a simple relationship. Two processes are at work in river channels -- the duration of floods, and the time it takes for the river to adjust to changes. The relative timescales of these phenomena dictate where avulsions occur.If floods are shorter than the time the river takes to adjust, then erosion and deposition are limited to the backwater zone. However, if floods last longer than it takes the river to adjust, erosion during floods can travel far upstream of the river mouth, which makes it possible for the river to avulse much farther inland.Large flat rivers, like the Mississippi, change slowly, but steep rivers with lots of fine sediment can adjust quite quickly. "The whole channel can be resurfaced within the backwater zone in a given flood," said Ganti, "and erosion can propagate much farther upstream." This is the case for rivers like those in Madagascar, which are relatively steep and have a lot of fine sediment.A river floods when it's carrying enough water to overtop its banks. And for most of its length, a flooded waterway will do just that. But water level is constrained by sea level near the river's mouth up through the backwater zone. So the increased volume of water during floods begins moving faster, increasing erosion, and scouring the river bed deeper.This wave of erosion can then spread upstream as flood conditions continue, enabling the river to avulse far upstream from the backwater zone -- much farther than anticipated.A foreboding picture emerges"Climate models predict that extreme floods will occur more often in a warming world," said Ganti. As a result, avulsions could begin moving even farther inland on rivers around the world.But greenhouse gas emissions are not the only human activity affecting rivers. Sand and gravel are critical components in construction and infrastructure, and humans are now mining these resources on massive scales. Unfortunately, these make up the coarse fraction of alluvial sediment, which means that our activities are leading to finer sediment in many locations. Rivers can carry more of this fine-grained material, and the increased load reduces the amount of time it takes channels [?] to change. Once again, this enables avulsions to occur farther upstream.What's more, sea level rise is pushing the backwater zone itself farther inland. These three factors combine to create the perfect recipe for major avulsions to occur ever farther inland on deltas, Ganti explained. This could lead to an increasing trend of homes, lives and livelihoods lost due to extreme flooding, likely in locations that never had to deal with these hazards historically.And according to the team's previous paper these events will also become more frequent as the sea level rises."We should brace ourselves for avulsion as a serious flood hazard in the future," Vamsi cautioned.River deltas have always been a critical resource for humanity, harnessed for agriculture, transportation and industry. Many of civilization's largest cities have grown along the banks of the world's great waterways. Their dynamism has always posed a challenge to society, but as rivers become less predictable and more volatile, researchers say, we will need to take more precautions to ensure our safety and wellbeing.
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Climate
| 2,020 |
September 30, 2020
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https://www.sciencedaily.com/releases/2020/09/200930144418.htm
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Planktonic sea snails and slugs may be more adaptable to ocean acidification than expected
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Pteropods, or "wing-footed" sea snails and slugs, may be more resilient to acidic oceans than previously thought, scientists report.
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By digging into their evolutionary history, the research team found that pteropods are much older than expected and survived past crises when the oceans became warmer and more acidic.Their findings, published on the 24th September 2020 in "Pteropods have been infamously called the "canaries in a coal mine" -- they act as an early warning signal for increased ocean acidity," said senior author Dr. Ferdinand Marlétaz, who is visiting faculty at the Okinawa Institute of Science and Technology Graduate University (OIST) and a former postdoctoral researcher in the OIST Molecular Genetics Unit, led by Pr. Daniel Rokhsar.Ocean acidification is one of the consequences of human-induced climate change and occurs when increasing levels of carbon dioxide in the atmosphere dissolve into the ocean, reacting with water to form carbonic acid. Acidic oceans detrimentally impact marine creatures in countless ways, from triggering coral bleaching to preventing marine organisms from building and maintaining their shells and skeletons.Pteropods are particularly vulnerable due to their aragonite shell, which over time has evolved to be thin and light-weight to suit their planktonic lifestyle. Aragonite is a highly soluble form of calcium carbonate. Dr. Marlétaz explained: "When conditions in the ocean are too acidic, these fragile shells can completely dissolve, and they die. So, pteropods will likely be seriously threatened as oceans acidify."This is an issue as pteropods play an important role in the ocean's ability to capture carbon as they use carbon dioxide to form their calcium carbonate shell. Pteropods are also commonly found in planktonic communities, so their loss could upset the delicate balance of the food webs in the open ocean.Many experimental studies are already testing the ability of pteropods to adapt to oceans with higher levels of carbon dioxide, but so far, little is known about their evolutionary history and how they might have responded to global changes in the past.To uncover their evolutionary history, Dr. Katja Peijnenburg from the Naturalis Biodiversity Center and the University of Amsterdam, pteropod expert and lead author of the study, collected samples of 21 different pteropod speciesfrom the Atlantic Ocean. The team then used these preserved samples to extract genetic information on 2654 genes. The researchers also included genetic data from three other species of pteropods and three species of sea slugs and snails that were closely related to pteropods.The scientists analyzed similarities and differences in the protein sequences of the genes shared across the species to construct an evolutionary tree. By calibrating the tree against pteropod fossils of a known date, the researchers could then calculate not only how, but when the main pteropod lineages diverged from a common ancestor to form new species."We found that the origin of the pteropods dated back to the early Cretaceous period when the main lineages of sea butterflies and sea angels diverged from each other, with the other main lineages splitting apart in the mid to late Cretaceous. This was much longer ago than previous molecular data had suggested and predates the oldest known fossils," said Dr. Marlétaz.Importantly, this new date of origin and earlier diversification means that the main groups of currently existing pteropods experienced periods of dramatic environmental change that caused mass extinction.Unlike the majority of species then present on earth, pteropods survived the asteroid strike at the end of the Cretaceous period around 66 million years ago which infamously wiped out the dinosaurs.But more importantly, pteropods also overcame the challenges of the Paleocene Eocene Thermal Maximum, a period about 55.5 million years ago where massive amounts of carbon dioxide released into the atmosphere caused the earth to warm and the oceans to acidify."The Paleocene Eocene Thermal Maximum was a period of crisis that was very similar to current changes we are seeing today," said Dr. Marlétaz. "These findings offer some hope that over evolutionary timescales, pteropods are able to adapt and acclimatize to changes in ocean temperature and acidity."However, Dr. Marlétaz also offered a word of caution. He explained that just because pteropods survived previous increases in ocean acidity, does not mean that they are necessarily resilient to the climate crisis occurring today."What is striking with the changes we see now is that they are happening at a much more dramatic pace than previous events," he said. "The main groups of pteropods have shown a robustness and ability to adapt over longer timescales, but the quicker the changes, the less chance these creatures have."
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Climate
| 2,020 |
September 30, 2020
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https://www.sciencedaily.com/releases/2020/09/200930114209.htm
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Greenland is on track to lose ice faster than in any century over 12,000 years
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If human societies don't sharply curb emissions of greenhouse gases, Greenland's rate of ice loss this century is likely to greatly outpace that of any century over the past 12,000 years, a new study concludes.
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The research will be published on Sept. 30 in the journal The findings place the ice sheet's modern decline in historical context, highlighting just how extreme and unusual projected losses for the 21st century could be, researchers say."Basically, we've altered our planet so much that the rates of ice sheet melt this century are on pace to be greater than anything we've seen under natural variability of the ice sheet over the past 12,000 years. We'll blow that out of the water if we don't make severe reductions to greenhouse gas emissions," says Jason Briner, PhD, professor of geology in the University at Buffalo College of Arts and Sciences. Briner led the collaborative study, coordinating the work of scientists from multiple disciplines and institutions."If the world goes on a massive energy diet, in line with a scenario that the Intergovernmental Panel on Climate Change calls RCP2.6, our model predicts that the Greenland Ice Sheet's rate of mass loss this century will be only slightly higher than anything experienced in the past 12,000 years," Briner adds. "But, more worrisome, is that under a high-emissions RCP8.5 scenario -- the one the Greenland Ice Sheet is now following -- the rate of mass loss could be about four times the highest values experienced under natural climate variability over the past 12,000 years."He and colleagues say the results reiterate the need for countries around the world to take action now to reduce emissions, slow the decline of ice sheets, and mitigate sea level rise. The research was largely funded by the U.S. National Science Foundation.The study brought together climate modelers, ice core scientists, remote sensing experts and paleoclimate researchers at UB, NASA's Jet Propulsion Laboratory (JPL), the University of Washington (UW), Columbia University's Lamont-Doherty Earth Observatory (LDEO), the University of California, Irvine (UCI) and other institutions.This multidisciplinary team used a state-of-the-art ice sheet model to simulate changes to the southwestern sector of the Greenland Ice Sheet, starting from the beginning of the Holocene epoch some 12,000 years ago and extending forward 80 years to 2100.Scientists tested the model's accuracy by comparing results of the model's simulations to historical evidence. The modeled results matched up well with data tied to actual measurements of the ice sheet made by satellites and aerial surveys in recent decades, and with field work identifying the ice sheet's ancient boundaries.Though the project focused on southwestern Greenland, research shows that changes in the rates of ice loss there tend to correspond tightly with changes across the entire ice sheet."We relied on the same ice sheet model to simulate the past, the present and the future," says co-author Jessica Badgeley, a PhD student in the UW Department of Earth and Space Sciences. "Thus, our comparisons of the ice sheet mass change through these time periods are internally consistent, which makes for a robust comparison between past and projected ice sheet changes.""We have significantly improved our understanding of how anomalous future Greenland change will be," says co-author Joshua Cuzzone, PhD, an assistant project scientist at UCI who completed much of his work on the study as a postdoctoral researcher at JPL and UCI. "This work represents a massive success for multidisciplinary science and collaboration, and represents a framework for future successful multidisciplinary work."Cuzzone and other researchers at UCI and JPL led ice sheet modeling, leveraging the work of colleagues at UW, who used data from ice cores to create maps of temperatures and precipitation in the study region that were used to drive the ice sheet model simulations up to the year 1850. Previously published climate data was used to drive the simulations after that date.UB and LDEO scientists partnered on field work that helped validate the model by identifying the ice sheet's boundaries in southwestern Greenland thousands of years ago."We built an extremely detailed geologic history of how the margin of the southwestern Greenland Ice Sheet moved through time by measuring beryllium-10 in boulders that sit on moraines," says co-author Nicolás Young, PhD, associate research professor at LDEO. "Moraines are large piles of debris that you can find on the landscape that mark the former edge of an ice sheet or glacier. A beryllium-10 measurement tells you how long that boulder and moraine have been sitting there, and therefore tells you when the ice sheet was at that exact spot and deposited that boulder."Amazingly, the model reproduced the geologic reconstruction really well. This gave us confidence that the ice sheet model was performing well and giving us meaningful results. You can model anything you want and your model will always spit out an answer, but we need some way to determine if the model is doing a good job."The study makes an important contribution by creating a timeline of the past, present and future of the Greenland Ice Sheet, Briner says. The results are sobering."We have long timelines of temperature change, past to present to future, that show the influence of greenhouse gases on Earth's temperature," Briner says. "And now, for the first time, we have a long timeline of the impacts of that temperature -- in the form of Greenland Ice Sheet melt -- from the past to present to future. And what it shows is eye-opening.""It is no secret that the Greenland Ice Sheet is in rough shape and is losing ice at an increasing rate," Young says. "But if someone wants to poke holes in this, they could simply ask, 'how do you know this isn't just part of the ice sheet's natural variability?' Well, what our study suggests is that the rate of ice loss for this century will exceed the rate of ice loss for any single century over the last 12,000 years. I think this is the first time that the current health of the Greenland Ice Sheet has been robustly placed into a long-term context."Despite these sobering results, one vital takeaway from the model's future projections is that it's still possible for people and countries around the world to make an important difference by cutting emissions, Briner says. Models of the RCP2.6 and RCP8.5 scenarios yield very different results, with high-emission scenarios producing massive declines in the ice sheet's health, and significant sea level rise."Our findings are yet another wake-up call, especially for countries like the U.S.," Briner says. "Americans use more energy per person than any other nation in the world. Our nation has produced more of the CO2 that resides in the atmosphere today than any other country. Americans need to go on an energy diet. The most affluent Americans, who have the highest energy footprint, can afford to make lifestyle changes, fly less, install solar panels and drive an energy-efficient vehicle.""This study shows that future ice loss is likely to be larger than anything that the ice sheet experienced in the Holocene -- unless we follow a low-carbon emission scenario in the future," Badgeley says.
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Climate
| 2,020 |
September 30, 2020
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https://www.sciencedaily.com/releases/2020/09/200930094734.htm
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How the Humboldt squid's genetic past and present can secure its future
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A group of marine biologists is pushing for more international collaboration to manage the Humboldt squid population after their study to identify its genetic stocks revealed its vulnerability to overfishing by fleets trying to feed the world's hunger for squids.
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Hiroshima University marine biologist Gustavo Sanchez led a team of researchers to find out the genetic structure of the Humboldt squid population in the Eastern Pacific Ocean using two types of DNA markers -- the mitochondrial ND2 gene and nuclear microsatellite loci.The team found that Humboldt squids could trace back their population to three historical matrilineage that spread out during the late Pleistocene and that the species has at least two contemporary genetic stocks homogeneously co-distributed in the northern and southern hemispheres.Different genetic stocks within a species are usually defined by where they feed and breed. But in Humboldt squids, DNA markers showed no north-south divide. The equator doesn't serve as a natural barrier to separate the different genetic stocks of these fast swimmers risking capture by different fishery fleets along their migration route."In our study, we identify at least two genetic stocks co-distributed in the north and southern hemisphere of the Eastern Pacific Ocean. Our results suggest that rather than independent marine policies from each country, the sustainability of this squid requires an international marine policy," Sanchez said.To ensure sustainable fishing, countries in South America where the squid is traditionally found have established yearly catch quotas. But the study found this approach to be ineffective, especially as catch restrictions are absent in international waters on the squid's migration path."Countries fishing this squid have established catch quotas with no consideration that the total amount varies from year to year, and that the amount of squid caught influences the number of squids next year. By doing so, the genetic contribution of the offspring every year will also clearly fluctuate. In such a situation, there is a risk of having a genetic erosion with a smaller number of squids which are also less likely to adapt rapidly to the changing environment," he remarked."From our study, it is also clear that the squids caught by different countries also belong at least two different populations, with likely different genetic contribution for the next generation. Catching these squids without knowing that their genetic contribution is different, is also very risky."Both warm tropical waters and the cooler Humboldt current, which runs from Tierra del Fuego at the southernmost tip of the South American mainland upwards to the northern coast of Peru, play a role in the Humboldt squid's life cycle.The squid seeks warm waters near the equator to spawn its clusters of neutrally buoyant eggs. But it needs nutrient-rich cool waters where they go on a feeding frenzy to grow from one-millimeter paralarvae specks to enormous predators of over 1.2 meters long.These squids typically spawn only once during their one-year lifespan then die, making their future volatile if fishing goes unchecked. And such fears are not farfetched.It's eastern relatives, the Japanese flying squid, has suffered the same fate. Years of overfishing, poor regulatory oversight, and the changing climate have depleted their population at an alarming rate that yearly catch of Japanese fishermen dropped over 70% from more than 200,000 tons in 2011 to 53,000 tons in 2017. The shortage worries the fishing town of Hakodate whose identity and economy are intertwined with the squid."The population of the Japanese flying squids has decreased, and this is because along the distribution of this squid you have a lot of fleets from Japan, China, Korea, and Taiwan, some with high capacity for catching this squid. Countries like China with massive distant-water fishing fleets can move anywhere outside their national jurisdiction to catch this squid. If you have the technology you can go to international waters and catch anything," Sanchez said.He said Hakodate's experience could be a grim warning of things to come for his country Peru."The Humboldt squid is the second most important economical species in Peru. That means that when we have less squid, that will affect also the economy of the country, particularly the economy of the fisherman that depends on this squid," he said.Over 90 percent of warming on Earth in the past 50 years has happened in the ocean and the speed it is heating up is accelerating. Warming oceans due to climate change have driven sea creatures toward the poles.The Humboldt squid population itself has expanded its migratory path. It recently stretched its route farther north to Alaska and south to the tip of Chile which exposes these cephalopods that hunt in packs of up to 1,200 to fishing boats in each territory on its path as well as technologically advanced vessels waiting in international waters.Sanchez's team found a similar pattern of historical population expansion under extreme climate conditions when they looked at the mitochondrial DNA of the squid. They found that warming global temperatures 30,000 years ago which thawed Ice Age glaciers contributed to a sea-level rise favorable for the Humboldt squid population to spread out. The event which coincided with the decrease in the population of sperm whales, their natural predators, led to a population expansion for the squids.Although quick to adapt, warmer temperatures mean less food, smaller maturity size, and fewer eggs to replenish its population.Much, including its conservation status, is still unknown of this large squid species. But with its economic significance to fishing communities and its important role in the marine ecosystem as food for diverse species, the new knowledge of its genetic stock can help inform future marine policies to manage its population."The Humboldt squid is the largest squid fishery in the world and is heavily caught in the Eastern Pacific Ocean by several countries, including countries from Asia like Japan, Korea, China, and Taiwan. This squid is one of the most commercial squids in the world, and it sustains the economy of many countries.""Identifying genetic stocks, also known as genetically different groups, throughout population genetics is very important for implementing marine policies that control the total catch of this squid. The high migratory capacity of this squid is the main challenge to identify the exact number of genetic stocks, and more genetic resources and sampling are required to clearly reveal this number."
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Climate
| 2,020 |
September 30, 2020
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https://www.sciencedaily.com/releases/2020/09/200930094745.htm
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Someday, even wet forests could burn due to climate change
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Millions of years ago, fire swept across the planet, fueled by an oxygen-rich atmosphere in which even wet forests burned, according to new research by University of Colorado Boulder scientists.
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The study, published today in "Studying this period in Earth's history can shine light on how the modern and future Earth might behave under global change," said F. Garrett Boudinot, lead author and recent PhD graduate in the Department of Geological Sciences.Boudinot analyzed samples from a rock core that spans what is known as the Oceanic Anoxic Event 2 (OAE2) in the Cretaceous period, about 94 million years ago. He found that an increased amount of carbon buried in the oceans at the start of this event was associated with indications for the occurrence of wildfires, which might have been caused by an increase in oxygen in the atmosphere."One of the consequences of having more oxygen in the atmosphere is that it's easier to burn fires," said Boudinot. "It's the same reason you blow on embers to stoke a fire."Large amounts of carbon dioxide in the atmosphere -- much like what Earth is projected to experience by 2100 -- kick-started this cycle.For 50,000 years before the OAE2 began, algae and land plants drew down this carbon into the oceans through photosynthesis, causing microbial respiration to increase, which led parts of the oceans to become low in or even devoid of oxygen, known as anoxia. This same process exists today in waters where too many nutrients end up in one place, like the mouth of the Mississippi River, where excess fertilizer runoff accumulates and feeds algae -- which are then eaten up by microbes that consume oxygen, creating a dead zone. In these kinds of anoxic waters, the organic carbon that is stored from the atmosphere is buried in sediments, while the oxygen that was part of the carbon dioxide (CO2) is released to the atmosphere.After 100,000 years of this ocean anoxia event -- which was intensified by warming temperatures -- oceans sediments around the globe had stored enough organic carbon that the atmosphere became rich in oxygen, so much so that it might have facilitated the burning of up to 40 percent of forests across the planet, even in wet and humid regions.The planet is undergoing a similar transformation today as it did at the beginning of this cycle, with carbon dioxide accumulating in the atmosphere and nutrients building up in the ocean. If these same patterns continue, history could repeat itself in the future, only centuries to millennia from today."It highlights that putting carbon dioxide into the atmosphere and nutrients into the ocean doesn't just potentially increase global temperatures. It has significant impacts on the fundamental biogeochemistry or ecology of the planet, like how forests respond to fire," said Boudinot, who now works in outreach at the Colorado Wildlife Council.A mystery in Earth's historyBoudinot never intended to analyze the rock core, drilled in Utah, for remnants of forest fires. It was drilled to better understand other various elements of OAE2, including how marine ecosystems responded to global change at that time in Earth's history.But he was also running another experiment at the same time, using an analytical method to identify molecular tracers of forest fires in rock samples from other times and locations. These tracers are called polycyclic, aromatic hydrocarbons, or PAHs -- sometimes known as "pyro PAHs."Within the Utah rock core were black shales laden with organic matter preserved from almost 94 million years ago, when that part of the country was covered with sea. So Boudinot thought why not? And ran these same tests on the OAE2 rock core, finding there were a significant amount of these pyro PAHs in it."These organic molecules basically serve as molecular fossils," said Julio Sepúlveda, senior author on the study, professor of geological sciences and fellow in the Institute of Arctic and Alpine Research.These molecules are also related to the temperature of the fire itself. They indicated high temperature fires, created by forest fires.The interval of OAE2 with more fires has also been something of a mystery to geologists. Not only is this new geochemical data rock solid, but it also represents a detailed evolution of the event -- with each data point representing a smaller period of time. This gives scientists a clearer understanding of how carbon storage in the oceans is related to oxygen levels in the atmosphere and global temperatures, and the pace at which these climate feedbacks can occur.While scientists suspect volcanic activity as the reason there was so much carbon dioxide in the atmosphere before this event in Earth's history began, Boudinot sees parallels to how much carbon dioxide humans are emitting today."This finding highlights the prolonged impacts of climate change. The climate change that we're causing now, it's not something where if we don't fix it, only our grandkids will have to deal with it," said Boudinot. "The history of climate change in Earth history tells us that the impacts are really long lasting."
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Climate
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September 30, 2020
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https://www.sciencedaily.com/releases/2020/09/200930085218.htm
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Redefining drought in the US corn belt
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As the climate trends warmer and drier, global food security increasingly hinges on crops' ability to withstand drought. But are scientists and producers focusing on the right metric when measuring crop-relevant drought? Not exactly, according to new research from University of Illinois scientists, who urge the scientific community to redefine the term.
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"Plants have to balance water supply and demand. Both are extremely critical, but people overlook the demand side of the equation, especially in the U.S. Corn Belt," says Kaiyu Guan, principal investigator on two new studies, Blue Waters professor in the Department of Natural Resources and Environmental Sciences and the National Center for Supercomputing Applications at Illinois.The demand Guan refers to is atmospheric dryness, often expressed as vapor pressure deficit (VPD). The drier the air, the more moisture is sucked out of pores, or stomata, in plant leaves. Plants have to open stomata to take in carbon dioxide as their food, but if they sense the atmosphere is too dry, they'll close pores to avoid drying out. Keeping stomata closed too long leads to reductions in photosynthesis, plant growth, and grain yield.The kicker? Plants shut down stomata due to atmospheric dryness even when there's an adequate supply of moisture in the soil."If you only consider rainfall and soil moisture, which is how most people think about drought, that's mostly describing the supply side. Of course if you have low soil moisture, plants will be stressed by how much water they get. But the supply is often pretty sufficient, especially here in the U.S. Corn Belt," Guan says. "However, the demand side from the atmosphere can also severely stress plants. We need to pay more attention to that drought signal."Guan's two recent studies used multiple technological approaches, including field measurements, various sources of satellite data, hydrological model simulations, and government crop yield statistics. The first study, published in "By comparison, soil moisture typically accounts for 6-13% of these measures for corn and soybean, and up to 35% when considering time lag effects," says Hyungsuk Kimm, doctoral student in Guan's group and the study's lead author.In the other study, published in the "This led us to build a new drought index integrating VPD, soil moisture, and measures of evapotranspiration, which can account for more than 70% of yield variation. Our index outperforms all the existing drought indices," says Wang Zhou, postdoctoral researcher in Guan's group and the study's lead author.Guan adds, "In these two studies, we tried to understand the demand side of drought from two major angles, one using eddy covariance data which measures landscape water and carbon use very accurately -- the gold standard -- and the other leveraging satellite data and model-simulated hydrological variables correlated with regional yield," Guan says. "In both, we demonstrate VPD is more important than soil moisture to explain the crop drought response in the U.S. Midwest."Adjusting the drought concept for crops will be critical for global food security under a changing climate."When we look at climate change scenarios, the amount of rainfall is not changing much for the Corn Belt, but we for sure know temperature and VPD will increase here. That means not much will change on the supply side, but demand stress will increase significantly. And that type of stress is so connected to end-of-season crop yield," Guan says.His group is working on follow-up studies evaluating the role of irrigation in increasing supply and decreasing demand, but for now, Guan says breeding for improved water-use-efficiency could be an important part of the solution.
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Climate
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September 29, 2020
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https://www.sciencedaily.com/releases/2020/09/200929123717.htm
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Volcanic ash could help reduce CO2 associated with climate change
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University of Southampton scientists investigating ways of removing carbon dioxide (CO
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A team from the University's School of Ocean and Earth Science has modelled the impact of spreading volcanic ash from a ship to an area of ocean floor to help amplify natural processes which lock away COThe researchers' findings are published in the journal Human-caused climate change is one of the most pressing topics in contemporary science and politics. The impact of hundreds of years of greenhouse gas emissions are becoming clearer every year, with environmental changes including heatwaves, droughts, wildfires, and other extreme weather events."As a result of overwhelming evidence, politicians have begun to take steps towards incorporating emissions reductions into policies, such as in the 2015 Paris Agreement with its long-term goal of ensuring that global average temperatures do not exceed 2°C above pre-industrial levels. However, it is becoming clear that to avoid the worst impacts of climate change, active greenhouse gas removal (GGR) will be required," explains study co-author and University of Southampton Professor of Geochemistry, Martin Palmer.GGR techniques remove carbon dioxide and other gases from the atmosphere, thereby reducing the greenhouse effect, and in the longer term, slowing climate change. There are numerous potential approaches to GGR, from the simple, such as reforestation, to the complex, such as actively removing COMost volcanoes lie close to the oceans, and every year millions of tonnes of volcanic ash falls into them and settles to the seafloor. Once there, it increases carbon storage in marine sediments and reduces atmospheric CO"One of the ways oceans lock away COThe scientists modelled the effect of distributing volcanic ash from a ship to an area of ocean. The results suggest that this method could sequester as much as 2300 tonnes of COThe scientists say further research is needed though to test the efficiency of enhanced ash deposition in the oceans and to make sure there are no unforeseen side effects, but initial indications suggest that it could be applied easily and cheaply in many areas of the world.
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Climate
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September 29, 2020
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https://www.sciencedaily.com/releases/2020/09/200929123625.htm
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Using microbial information to inform global climate change models
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Jizhong Zhou, the Director of the Institute for Environmental Genomics, a George Lynn Cross Research Professor in the OU College of Arts and Sciences and the lead for the study, tackles a problem that has challenged scientists for more than a decade.
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"Soil microbial respiration, which is the carbon dioxide flux from the soil to the atmosphere, is an important source of uncertainty in projecting future climate and carbon cycle feedbacks," said Zhou. "Our study illustrates that warming-induced respiratory adaptation is subject to the adaptive changes in microbial community functional structure, so that the positive feedback of soil microbial respiration in response to climate warming may be less than previously expected."He adds that this study is also unique in its approach to integrate omics data, the term for the comprehensive approach for analysis of complete genetic profiles of organisms and communities, into ecosystem models for better predictions."Integrating microbial omics information to inform global climate change models is extremely challenging," Zhou said. "The findings from this study have important implications for understanding and predicting the ecological consequences of climate warming."
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Climate
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September 29, 2020
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https://www.sciencedaily.com/releases/2020/09/200929123552.htm
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Potential for natural forest regrowth to capture carbon
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Researchers from Australia's national science agency CSIRO joined scientists from 17 other countries to publish a first of its kind, 'wall-to-wall' global, 1km resolution map that highlights areas with the greatest carbon returns, when they are allowed to reforest naturally.
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The report, led by The Nature Conservancy, highlights the role of natural forest regrowth and refines previous international estimates, said co-author Dr Stephen Roxburgh, Principal Research Scientist at the CSIRO.Dr Roxburgh said CSIRO supported the study through the supply of datasets, including 72 stands of natural regeneration that CSIRO had surveyed for biomass carbon.These datasets were collected for the Australian Government's national greenhouse gas accounting program. The datasets were also used to better understand the carbon storage potential from restoring degraded woody vegetation.This global study complements recent Australian work on carbon accumulation rates for planted and naturally regenerating stands of woody biomass across Australia. Human induced natural regeneration of woody vegetation is a substantial contributor to carbon storage activities being carried out under Australia's Emissions Reduction Fund.The study found that climate, rather than past land use, was the most important driver of potential carbon accumulation, with the work providing an important benchmark to assess the global potential of forest regrowth as a climate mitigation strategy, said Dr Roxburgh.This project is jointly funded by CSIRO and the Australian Government's National Environmental Science Program.
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Climate
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September 29, 2020
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https://www.sciencedaily.com/releases/2020/09/200929123532.htm
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More accurate modelling of climate change impacts on water resources
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To better document the repercussions of climate change on regional water resources, researchers from around the world now have access to HYSETS, a database of hydrometric, meteorological and physiographic data created by a team at the École de technologie supérieure (ÉTS), which contains 70 years' worth of data on 14,425 North American watersheds.
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"Given the diversity of its data and the number of regions documented, HYSETS will allow you to develop models for virtually any type of climate," explained Richard Arsenault, professor of construction engineering and a member of the Hydrology, Climate and Climate Change Laboratory (HC3), at ÉTS, who spearheaded the project. These ready-to-use data are offered free of charge (see: "Normally, we have to draw the data we need from several different databases, then filter them before being able to use them to create a reliable model. This task must be repeated each time we want to create a model. We thought it would be a good idea to create a huge database with ready-to-use data that could serve the entire scientific community," explained Richard Arsenault.HYSETS stands out from other existing databases for many reasons.First of all, for the number of watersheds that it describes: while most current datasets are based on a sample of around 800 watersheds, HYSETS takes into account 14,425. As for the few databases of greater size -- which sometimes include up to 30,000 watersheds -, their flaw is they contain only a single category of data (for example: weather data or hydrometric data, but not the two together). On the other hand, HYSETS contains hydrometric, meteorological and physiographic data from diverse sources and from three North American countries. This diversity is highly useful, if not necessary, to better understanding the propagation of uncertainties in water resource management chains.Another notable fact: the HYSETS data covers a long period of time, from 1950 to 2018. The database will be augmented annually with data from the previous year. This will make it highly useful for studying past and more recent changes in hydroclimatic variables across different regions of North America.Finally, the HYSETS database can be used as a test environment for a wide range of applications, including hydrological modeling. Thanks to multiple datasets on temperatures and precipitation, the database can assist in correcting biases in worldwide and regional climate models.It's an undeniable asset for researchers in hydrology, environment and climate sciences, because it's easier to develop models using a significant number of regions. In addition, current studies rely more and more on large scale data in order to take into account the instabilities created by climate change.
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Climate
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September 29, 2020
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https://www.sciencedaily.com/releases/2020/09/200929123500.htm
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Marine biodiversity reshuffles under warmer and sea ice-free Pacific Arctic
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Climate warming will alter marine community compositions as species are expected to shift poleward, significantly impacting the Arctic marine ecosystem.
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The biodiversity of marine communities in the Pacific Arctic under future climate change scenarios highlights profound changes relative to their present patterns. Alterations in marine species distributions in response to warming and sea ice reduction are likely to increase the susceptibility and vulnerability of Arctic ecosystems. The findings, published by Hokkaido University researchers in the journal Fisheries oceanographer Irene Alabia of Hokkaido University's Arctic Research Center along with colleagues in Japan and the US investigated how future climate changes will impact the marine biodiversity in the Bering and Chukchi Seas. These seas extend from Alaska to Russia in the northern Pacific and southern Arctic oceans."This area forms a 'biogeographical transition zone': a biodiversity-rich region covering two distinct areas with specific features that encourage the coexistence of species living at or close to their distribution limits," explains Alabia. "These zones are vulnerable to climate warming, and climatic disruptions can create favorable conditions for the shift of warm-water species into previously colder-water zones."Scientists are interested in understanding how species in biogeographical transition zones are responding to climate changes and other human impacts. This information could help in conservation planning, fisheries management, and in studying the role of evolutionary history in shaping currently existing communities.Alabia and her team mapped the present and future spatial distributions of 26 fish and invertebrate species in the Bering and Chukchi Seas. Using species records, sea surface temperature, and sea ice concentration data, the authors developed species distribution models to predict the distributional ranges under the present-day (1993-2017) and future (2026-2100) climate conditions. From the model outputs, the changes in species richness and compositional diversity in terms of species' phylogeny and functional traits between time periods and across contrasting levels of warming were elucidated.The findings suggest that larger, longer-lived and more predatory fish and invertebrates will expand their ranges towards the pole in response to warming waters and sea ice free conditions by the end of the 21st century. These poleward shifts could alter the structure, composition and functions of future Arctic communities, which are currently dominated by smaller and short-lived species. The future species pool in the Arctic waters will also have more similar functions within the ecosystem, impacting regional food webs. It is also likely that there will be considerable socioeconomic impacts, as commercially important species shift northwards, which could increase operational fishing costs."These projected impacts are expected to raise challenges for ocean governance, conservation and resource management of shifting fisheries," says Alabia. "Our results provided glimpses of potential futures of the Arctic marine ecosystems, nonetheless, and some of these ecological shifts are already being documented. As such this highlights the need for continued monitoring and improving climate-ready strategies to buffer climate change impacts and maintain the integrity and functioning of vulnerable ecosystems."
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Climate
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September 29, 2020
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https://www.sciencedaily.com/releases/2020/09/200929123344.htm
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Lessons from a cooling climate
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Usually, talk of carbon sequestration focuses on plants: forests storing carbon in the trunks of massive trees, algae blooming and sinking to the seabed, or perhaps peatlands locking carbon away for tens of thousands of years.
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While it's true that plants take up large amounts of carbon from the atmosphere, the rocks themselves mediate a great deal of the carbon cycle over geological timescales. Processes like volcano eruptions, mountain building and erosion are responsible for moving carbon through Earth's atmosphere, surface and mantle.In March 2019, a team led by UC Santa Barbara's Francis Macdonald published a study proposing that tectonic activity in the tropics, and subsequent chemical weathering by the abundant rainfall, could account for the majority of carbon capture over million-year timeframes.Now, Macdonald, doctoral student Eliel Anttila and their collaborators have applied their new model to the emergence of the Southeast Asian archipelago -- comprising New Guinea, Indonesia, Malaysia, the Philippines and other nearby islands -- over the past 15 million years. Using data from the paleo-record, they determined that the islands are a modern hotspot of carbon dioxide consumption. Their results, published in the The primary means by which carbon is recycled into the planet's interior is through the breakdown of silicate rocks, especially rocks high in calcium and magnesium. Raindrops absorb carbon dioxide from the atmosphere and bring it to the surface. As the droplets patter against the stone, the dissolved carbon dioxide reacts with the rocks, releasing the calcium and magnesium into rivers and the ocean. These ions then react with dissolved carbon in the ocean and form carbonate compounds like calcite, which consolidates on the sea floor, trapping the atmospheric carbon for tens of millions of years or longer.Given the right conditions, and enough time, the deep carbon cycle can lock away enough carbon to plunge Earth into an ice age. "Last year we found that there was a nice correlation between when we make a bunch of mountains in the tropical rain belt and when we have cooling events," said Macdonald, a professor in the Department of Earth Science.Carbon dioxide levels in the atmosphere spiked in the mid-Miocene climatic maximum, around 15 million years ago. Although there is still some uncertainty, scientists believe that atmospheric COToday we are around 411 ppm, and climbing, Macdonald pointed out.Around that time, the Eurasian and Australian plates began colliding and creating the Southeast Asian archipelago and few of the present islands were emergent above sea-level. "This is the most recent example of an arc-continent collision in the tropics," Macdonald noted, "and throughout this period we actually have proxy data for the change in COThe team was curious how large an effect the emergence of the islands may have had on the climate. Based on their previous hypothesis, the formation of these largely volcanic rock provinces in the tropics should be a major factor in determining COThey applied geological data of ancient shorelines and lithology to a joint weathering and climate model, which accounted for four major variables: latitude, topography, total area and rock type. In the tropics, a more mountainous region will experience more rain, and have a greater surface area for weathering to occur. Once the surface rocks are weathered, the combination of erosion and uplift exposes fresh rock."What you need to do is just keep removing that soil, keep getting fresh rock there, and keep dissolving it," explained Macdonald. "So having active tectonic topography is key. All of Southeast Asia has active topography, and this is a big reason why it's just so much more effective at breaking rocks down into their constituent ions so they can join into the geochemical cycles."The team's analysis bore this out. They found that weathering, uplift, and erosion just in the Southeast Asian islands could have accounted for most of the drop in COThese findings could provide insights on our current climate crisis. "The reason scientists are so interested in understanding the Miocene is because we think of this as perhaps the best natural analogue to what the world may look like at a CO"People should be worried not necessarily about the amplitude of the increase, but the slope," added Anttila. "That's that real problem right now." Humans have moved a comparable amount of carbon into the atmosphere in just a few generations as it took the Earth to pull out of the atmosphere over millions of years."You realize that we are more effective than any geological processes at geoengineering," Macdonald said.The team is currently developing a model and looking at the rocks themselves to reevaluate previous hypotheses for the initial cooling. By a stroke of good fortune, the original specimens used to develop these hypotheses are from the Monterey Formation, a layer of rock that crops up throughout the Santa Barbara basin. These rocks dominate cliff faces from Santa Barbara to Goleta Pier and from Coal Oil Point to Gaviota."We've got this amazing opportunity right here to reconstruct this time period, right in our backyard," said Macdonald."These records of going from a warmer climate in the Miocene to the cooler climate of today are recorded right here in the cliffs," he added. "So further tests of the hypotheses -- especially in quarantine times, when we can't travel -- may just involve going out to the beach."
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Climate
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September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928155748.htm
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Ancient Adélie penguin colony revealed by snowmelt at Cape Irizar, Ross Sea, Antarctica
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Researcher Steven Emslie encountered a puzzle at Cape Irizar, a rocky cape located just south of the Drygalski Ice Tongue on the Scott Coast, Ross Sea. He found both ancient and what appeared to be fresh remains of Adelie penguins, mostly of chicks, which frequently die and accumulate at these colonies. However, the "fresh" remains were puzzling, he says, because there are no records of an active penguin colony at this site since the first explorers (Robert Falcon Scott) in 1901-1903 came to the Ross Sea.
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Emslie found abundant penguin chick bones scattered on the surface, along with guano stains, implying recent use of the site, but that wasn't possible, says Emslie. Some of the bones were complete chick carcasses with feathers, now falling apart from decay as at a modern colony, as well as intact mummies. Emslie and his colleagues collected some of these surface remains for further analysis and radiocarbon dating to try and figure out what was going on there.The team found old pebble mounds scattered about the cape. These mounds are former nesting sites of Adélie penguins because they use pebbles to build their nests. When they abandon a site, the pebbles become scattered and stand out on the landscape, since they are all about the same size."We excavated into three of these mounds, using methods similar to archaeologists, to recover preserved tissues of penguin bone, feather, and eggshell, as well as hard parts of prey from the guano (fish bones, otoliths). The soil was very dry and dusty, just as I've found at other very old sites I've worked on in the Ross Sea, and also had abundant penguin remains in them. Overall, our sampling recovered a mixture of old and what appeared to be recent penguin remains implying multiple periods of occupation and abandonment of this cape over thousands of years. In all the years I have been doing this research in Antarctica, I've never seen a site quite like this."The analyses reported in Emslie's recent paper published in Global warming has increased the annual temperature in the Ross Sea by 1.5-2.0 °C since the 1980s, and satellite imagery over the past decade shows the cape gradually emerging from under the snow. Thus, says Emslie, "This recent snowmelt revealing long-preserved remains that were frozen and buried until now is the best explanation for the jumble of penguin remains of different ages that we found there."
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928155746.htm
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The Arctic is burning in a whole new way
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"Zombie fires" and burning of fire-resistant vegetation are new features driving Arctic fires -- with strong consequences for the global climate -- warn international fire scientists in a commentary published in
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The 2020 Arctic wildfire season began two months early and was unprecedented in scope."It's not just the amount of burned area that is alarming," said Dr. Merritt Turetsky, a coauthor of the study who is a fire and permafrost ecologist at the University of Colorado Boulder. "There are other trends we noticed in the satellite data that tell us how the Arctic fire regime is changing and what this spells for our climate future."The scientists contend that input and expertise of Indigenous and other local and communities is essential to understanding and managing this global issue.The commentary identifies two new features of recent Arctic fires. The first is the prevalence of holdover fires, also called zombie fires. Fire from a previous growing season can smolder in carbon-rich peat underground over the winter, then re-ignite on the surface as soon as the weather warms in spring."We know little about the consequences of holdover fires in the Arctic," noted Turetsky, "except that they represent momentum in the climate system and can mean that severe fires in one year set the stage for more burning the next summer."The second feature is the new occurrence of fire in fire-resistant landscapes. As tundra in the far north becomes hotter and drier under the influence of a warmer climate, vegetation types not typically thought of as fuels are starting to catch fire: dwarf shrubs, sedges, grass, moss, even surface peats. Wet landscapes like bogs, fens, and marshes are also becoming vulnerable to burning.The team has been tracking fire activity in the Russian Arctic in real time using a variety of satellite and remote sensing tools. While wildfires on permafrost in Siberia south of the Arctic are not uncommon, the team found that 2019 and 2020 stood out as extreme in the satellite record for burning that occurred well above the Arctic Circle, a region not normally known to support large wildfires.As a result, said lead author Dr. Jessica McCarty, a geographer and fire scientist at Miami University, "Arctic fires are burning earlier and farther north, in landscapes previously thought to be fire resistant."The consequences of this new fire regime could be significant for the Arctic landscape and peoples and for the global climate. More than half of the fires detected in Siberia this year were north of the Arctic Circle on permafrost with a high percentage of ground ice. This type of permafrost locks in enormous amounts of carbon from ancient biomass. Climate models don't account for the rapid thaw of these environments and resulting release of greenhouse gases, including methane.On a more local level, abrupt thawing of ice-rich permafrost in wildfires causes subsidence, floods, pits and craters, and can submerge large areas under lakes and wetlands. As well as disrupting the lives and livelihoods of Arctic residents, these features are associated with more greenhouse gases moving from where they are trapped in soils into the atmosphere.These extensive changes have severe consequences for global climate."Nearly all of this year's fires inside the Arctic Circle have occurred on continuous permafrost, with over half of these burning on ancient carbon-rich peat soils," said Dr. Thomas Smith, a fire scientist at the London School of Economics and Political Science and a coauthor of the study. "The record high temperatures and associated fires have the potential to turn this important carbon sink into a carbon source, driving further global heating."The severity of the 2020 Arctic fires emphasizes an urgent need to better understand a switch in Arctic fire regimes. New tools and approaches are required to measure how fires start and measure fire extent. Modeling tools and remote sensing data can help, but only if paired with local, specialized knowledge about where legacy carbon stored in peats or permafrost is vulnerable to burning and how environments change after wildfires.The commentary cautions that this issue is so important to the climate system that it must be taken up as an issue of global importance. It outlines a path forward for not only understanding the role of changing fire in the Arctic but to ensure that research stays focused on local community and policy needs."We need global cooperation, investment, and action in monitoring fires, including learning from Indigenous and local communities how fire is traditionally used," said McCarty. "We need new permafrost- and peat-sensitive approaches to wildland fire fighting to save the Arctic -- there's no time to lose."
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Climate
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September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928152922.htm
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Disastrous duo: Heatwaves and droughts
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Simultaneous heatwaves and droughts are becoming increasingly common in western parts of the Unites States, according to a new study led by researchers from McGill University. Periods of dry and hot weather, which can make wildfires more likely, are becoming larger, more intense, and more frequent because of climate change.
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In a study published by "Dry-hot events can cause large fires. Add wind and a source of ignition, and this results in 'megafires' like the 2020 fires across the west coast of the United States. Drought and record-breaking heatwaves, coupled with a storm that brought strong winds and 12,000 lightning events in a span of 72 hours, caused more than 500 wildfires," says lead author Mohammad Reza Alizadeh, a PhD student under the supervision of Professor Jan Adamowski in the Department of Bioresource Engineering at McGill University.The researchers also found that dry and hot weather events are intensifying, with longer periods of drought and higher temperatures. These dual "dry-hot extremes" are not only self-intensifying -- more heat causes more drought and vice versa -- but are also self-propagating, meaning they are able to move from region to region. "As increased temperatures are driving and expanding aridity, droughts and heatwaves move from one region to downwind regions," says Alizadeh. These extremes can be particularly damaging for agricultural production and ecosystems, they warn.According to the researchers, the trigger for these hot-dry events is shifting. Looking back at the catastrophic Dust Bowl of the 1930s, they explain that the dust storms were driven by a lack of rainfall coupled with poor land management practices. In recent decades, however, dry-hot disasters are driven more often by excess heat than a lack of rainfall.The future will bring us more of these disasters, if the current warming trends continue, the researchers caution. They suggest their findings could be used to inform climate mitigation and adaptation efforts. "We need to understand how things are changing in order to adapt," says Professor Jan Adamowski.
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928152909.htm
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Climate change threatens breeding birds
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The researchers, who examined decades of data on weather, food availability and breeding in Tree Swallows, say that the timing of when to breed and when food is available is becoming decoupled for some animals -- highlighting the complexity behind how organisms respond to climate change. "Simply moving dates earlier to track climate change isn't necessarily risk free. Riskier conditions earlier in the year can expose animals to unintended consequences when responding to bouts of unusually warm spring weather," says Ryan Shipley, postdoctoral fellow at the Max Planck Institute of Animal Behavior and first author on the paper.
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In recent years, studies have raised concerns about whether or not species can adapt, or "keep pace" with climate change. Particular emphasis has been placed on phenology -- the timing of life cycle events such as breeding and migration -- and the importance of adjusting this to track rising temperatures and earlier arrivals of spring. But the authors say that breeding earlier may place animals at greater risk of exposure to inclement weather events that tend to occur more frequently earlier in the year. They found that Tree Swallows had been advancing breeding by three days every decade for the last 30 years, but earlier-hatching offspring were at greater risk of exposure to inclement weather, which in turn reduced the availability of the flying insects they rely on for food."Our results raise the possibility that animals relying on food resources that can rapidly change in abundance due to the weather may be particularly at risk to climate change," says Shipley. The study has exposed strong fitness consequences for birds that are advancing breeding at a similar rate to climate change. But it may also provide clues to the mystery of why aerial insectivorous birds, such as swallows, swifts, flycatchers, and nightjars, are declining faster than other groups in much of North America and Europe. Weather in spring can change quickly and tends to be more unpredictable earlier in the year.The activity of flying insects is determined by weather, which means they are stochastically available. "For birds that feed on flying insects, one day is feast, the next is famine. This means during unusually warm springs, parents are betting current conditions that prompt earlier egg laying are indicative of similar good conditions for rearing hatched young three weeks in the future," says Shipley.The results lay bare a previously unobserved threat to aerial insectivorous birds. "Considerable attention has been given to potential widespread decline of insect populations and this might be hitting insectivorous birds particularly hard. But we show a mechanism that doesn't require change in insect abundance -- just availability over short time, like a few days."The researchers studied a population of Tree Swallows in Ithaca, New York, that have been the focus of a remarkable 30-year experiment -- studies of this length are rare in the field of ornithology. This allowed them to analyse a series of long-term data of Tree Swallow reproduction (over 30 years) daily insect abundance (over 25 years) and weather (over 100 years)."Long-term studies like this one are vital for understanding how and why species are affected by changing climates. They can also provide valuable insights into how organisms function, interact in complex ecological networks, and evolve," says Maren Vitousek, Associate Professor in the Department of Ecology and Evolutionary Biology at Cornell University, and co-author on the study, who runs the longterm Tree Swallow experimental site in Ithaca.
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928152848.htm
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Despite high hopes, carbon absorbed by Amazon forest recovery is dwarfed by deforestation emissions
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Regrowing forests are absorbing just a small proportion of the carbon dioxide released from widespread deforestation in the Amazon, according to new evidence.
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Secondary forests -- areas of new forest growing on land that has previously been deforested -- form a key part of policies aiming to tackle net carbon emissions and mitigate climate change.In 2017 there were nearly 130,000 square kilometres of secondary forest in the Brazilian Amazon -- roughly equivalent to the size of England.Despite their scale and importance for climate targets, our understanding of their contribution to the tropical carbon balance is incomplete. It was not clear to what extent carbon emissions from deforestation have been offset by secondary forest growth, or how this has varied over time.A new study by an international team of researchers from the UK and Brazil, published by After calculating how much carbon had been lost through deforestation, the scientists discovered that, in more than 30 years, the regrowth of secondary forests in the Brazilian Amazon has offset less than 10 per cent of emissions from the loss of old-growth forests.Charlotte Smith, a PhD researcher at Lancaster University and lead author of the study, said: "Secondary forests have an incredible potential to store large quantities of carbon. However, it takes a long time for them to build this carbon stock, so without a drastic decline in the rate of deforestation their environmental benefits will continue to be undermined."Despite a fifth of deforested land now being covered in secondary forest, the researchers found that most secondary forests are relatively young -- more than 85 per cent are younger than 20 years old and almost half (42 per cent) are less than five years old.This is because secondary forests are also subject to deforestation. Areas of land have been repeatedly deforested -- thus limiting secondary forests' effectiveness as a carbon store. "Of all the secondary forest mapped over the 32-year period, 60 per cent had been deforested again by 2017," said Charlotte.The researchers then looked at other factors known to affect secondary forest growth and carbon up-take, such as climate, landscape and proximity to old-growth forests, which can act as a source of seeds.They found that the majority of secondary forests are situated far from primary forests, in the drier parts of the Amazon. These factors suggest they will be relatively poor for taking-up carbon.The findings highlight that halting deforestation, particularly of old-growth forest, is essential and that secondary forest growth alone is not sufficient to control carbon emissions in the Amazon.Co-author, Professor Jos Barlow, said: "Although secondary forests could be an important part of the solution to climate change, it is also important not to overstate their relevance. Deforestation rates in the Brazilian Amazon surpassed 10,000km2 last year, and will almost certainly surpass that in 2020."The researchers hope that these results will help inform policies and management proposals that can mitigate climate change more effectively. "We show that preventing further deforestation remains the most urgent priority to mitigate climate change," said Charlotte.
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928125113.htm
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Spreading ghost forests on NC coast may contribute to climate change
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A new study found the spread of ghost forests across a coastal region of North Carolina may have implications for global warming. Ghost forests are areas where rising seas have killed off freshwater-dependent trees, leaving dead or dying white snags standing in marsh.
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The study found that the transition from forest to marsh along the coastline of the Albemarle-Pamlico Peninsula led to a significant loss in the amount of carbon stored in the plants and trees above ground. When released into the atmosphere as a gas, carbon can contribute to global warming. However, researchers also uncovered some ways landowners can offset some of those carbon losses."Many people think about sea-level rise as being more of a long-term threat," said the study's lead author Lindsey Smart, a research associate at the North Carolina State University Center for Geospatial Analytics. "But we're actually seeing significant changes over shorter time periods because of this interaction between gradual sea-level rise and extreme weather events like hurricanes or droughts, which can bring salt water further inland."In the study, researchers tracked the spread of ghost forests across 2,485 square miles on the peninsula. They found that on unmanaged, or natural, land such as publicly owned wildlife areas, ghost forests spread across 15 percent of the area between 2001 and 2014.Using models created using data on vegetation height and type in the area, they calculated that across the 13 years of the study, 130,000 metric tons of carbon were lost from the spread of ghost forests on unmanaged land.According to the U.S. Environmental Protection Agency's Greenhouse Gas Equivalencies Calculator, that's equivalent to what would be emitted into the air by 102,900 passenger vehicles driven for one year."Coastal forests are really unique in that they store carbon both in their foliage, and in their really rich organic soil," Smart said. "As saltwater intrusion increases, you're going to see impacts both to the aboveground and the belowground carbon. While we measured aboveground carbon losses, the next step will be to look at the response of these carbon stores below ground to saltwater exposure."Researchers said it's unclear exactly what happens to the carbon released when the forests are killed by salt water, and it could be that it goes into the soil.While they found ghost forests spread along the peninsula's coastline, they also saw that the losses at the coast were offset by tree plantings in forests grown for timber during the study.That was one land-management practice that they found could offset carbon losses due to ghost forest spread. They also saw that the use of canals and drainage ditches had an impact on carbon losses. Canals could either aid saltwater encroachment on the land, or help prevent it, depending on their use."Drainage networks, if not maintained, can serve as conduits for saltwater intrusion," Smart said.They also reported that catastrophic wildfires likely worsened the spread of ghost forest along the coast and had a greater impact on the loss of aboveground carbon compared with ghost forest spread."We think there may be an interaction between salt water and fire that accelerates forest retreat, and facilitates marsh migration into areas that were once healthy coastal forest," Smart said.The researchers said drought also played a role in ghost forest spreads."Two severe droughts within the study period produced larger-than-typical wildfires and facilitated salinization of normally freshwater ecosystems," said study co-author Paul Taillie, a postdoctoral researcher at the University of Florida and former graduate student at N.C. State. "Thus the combination of rising sea level and future drought would be expected to cause a large net loss in biomass."Overall, the study helps create a map of areas that are particularly vulnerable to sea-level rise, and offers clues to help prevent loss of coastal forests."Our paper helps to identify areas that are most vulnerable to the impact of sea-level rise and extreme weather events," Smart said. "This could help guide land-management decisions and help people think about ways to adapt to these changing environmental conditions."
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928125109.htm
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Natural capital a missing piece in climate policy
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Clean air, clean water and a functioning ecosystem are considered priceless. Yet the economic value of nature remains elusive in cost-benefit analysis of climate policy regulations and greenhouse-gas-reduction efforts.
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A study published today in the journal "It may seem abstract, with terms like 'natural capital,' but these are real things," said senior author Frances Moore, a professor in the UC Davis Department of Environmental Science and Policy. "What we're talking about is thousands of species being at high risk of extinction and large-scale changes to the ecosystem services we depend on for our lives and our economy. At the end of the day, this paper addresses some fundamental questions of how humans depend on nature for their wellbeing."Climate economic models typically represent the economy as made of two building blocks: human capital (labor) and manufactured capital, such as buildings and machines. This study incorporates a third building block -- natural capital -- which comprises the natural systems and healthy habitats for species. Natural capital translates into tangible benefits for people, such as erosion control, and intangible benefits, such as preserving forests for future generations."If lost, such natural processes cannot easily be replaced or substituted," said lead author Bernardo Bastien-Olvera, a Ph.D. candidate in the UC Davis Geography Graduate Group. "The associated economic costs of that loss are damaging in a way not currently represented in climate economic models or policy."The authors found that under plausible assumptions about how natural capital supports economic production and human welfare, climate damage to natural systems warrants rapid mitigation. Most previous analysis has ignored the pathways by which natural systems support welfare and their unique vulnerability to climate change -- potentially missing a critical piece of climate damages.Federal agencies use the "social cost of carbon" to represent the long-term damage done by a ton of CO2 emissions in a given year. The metric is widely used in cost-benefit analyses of climate and energy policy. Yet standard estimates only roughly account for ecological damages and do not fully account for the unique and long-term costs of climate impacts on natural systems. Because of this, the study finds that the federal social cost of carbon may well be far too low."With this new framework, we are more aware of the need to limit emissions," Bastien-Olvera said. "We calculate the emissions pathway that maximizes social welfare in the model. That pathway limits warming to 1.5 degrees Celsius by 2100, consistent with goals of the Paris Agreement. The clues keep leading us to the same conclusion -- the need to urgently reduce emissions to limit warming."
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928125106.htm
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Increasing stability decreases ocean productivity, reduces carbon burial
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As the globe warms, the atmosphere is becoming more unstable, but the oceans are becoming more stable, according to an international team of climate scientists, who say that the increase in stability is greater than predicted and a stable ocean will absorb less carbon and be less productive.
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Stable conditions in the atmosphere favor fair weather. However, when the ocean is stable, the layers of the ocean do not mix. Cooler, oxygenated water from beneath does not rise up and deliver oxygen and nutrients to waters near the surface, and warm surface water does not absorb carbon dioxide and bury it at depth."The same process, global warming, is both making the atmosphere less stable and the oceans more stable," said Michael Mann, distinguished professor of atmospheric sciences and director of the Earth System Science Center at Penn State. "Water near the ocean's surface is warming faster than the water below. That makes the oceans become more stable."Just as hot air rises, as is seen in the formation of towering clouds, hot water rises as well because it is less dense than cold water. If the hottest water is on top, vertical mixing in the oceans slows. Also, melting ice from various glaciers introduces fresh water into the upper layers of the oceans. Fresh water is less dense than salt water and so it tends to remain on the surface as well. Both elevated temperature and salinity cause greater ocean stratification and less ocean mixing."The ability of the oceans to bury heat from the atmosphere and mitigate global warming is made more difficult when the ocean becomes more stratified and there is less mixing," said Mann. "Less downward mixing of warming waters means the ocean surface warms even faster, leading, for example, to more powerful hurricanes. Global climate models underestimate these trends."Mann and his team are not the first to investigate the impact of a warming climate on ocean stratification, but they are looking at the problem in a different way. The team has gone deeper into the ocean than previous research and they have a more sophisticated method of dealing with gaps in the data. They report their results today (Sept. 29) in "Other researchers filled in gaps in the data with long-term averages," said Mann. "That tends to suppress any trends that are present. We used an ocean model to fill in the gaps, allowing the physics of the model to determine the most likely values of the missing data points."According to Mann, this is a more dynamic approach."Using the more sophisticated physics-based method, we find that ocean stability is increasing faster than we thought before and faster than models predict, with worrying potential consequences," he said.
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928125042.htm
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Landslides: long-term effects on tundra vegetation
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Landslides have long-term effects on tundra vegetation, a new study shows. Conducting the study in North West Siberia, the researchers found that tundra vegetation regenerated rapidly after a major landslide event in 1989. Two decades later, differences in the vegetation of the landslide area and the areas surrounding it have evened out, but even after 30 years, the vegetation of the landslide area is nowhere close to the vegetation of the surrounding areas.
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Several studies have reported changes in the Normalized Difference Vegetation Index (NDVI) in Arctic regions. So far, remote sensing data that is used to calculate the NDVI hasn't been able to discern, in detail, landscape level factors that have an effect on, e.g., greening."Landslides caused by the thawing of permafrost will become increasingly common in North West Siberia and elsewhere in the Arctic, too. These are caused by climate change and they also have an effect on vegetation. However, the exact effect of landslides on NDVI is difficult to discern from low-resolution satellite data," Professor Timo Kumpula from the University of Eastern Finland says.The researchers point out that permafrost thawing also has implications for all construction. Indeed, the Bovanenkovo gas field, one of Russia's largest gas fields in the Arctic, is located in the study site. Permafrost thawing can cause structural collapses and put infrastructure at risk. This, in turn, could lead to various types of environmental damage.Published in "VHR satellite images allow us to see very small changes in the land cover, such as temporary degradation of vegetation or new landslides that can be very small, even less than 0.1 hectares in size. We can also see sites where existing permafrost thawing expands," Researcher Mariana Verdonen from the University of Eastern Finland says.
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928093742.htm
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Sentinels of ocean acidification impacts survived Earth's last mass extinction
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Two groups of tiny, delicate marine organisms, sea butterflies and sea angels, were found to be surprisingly resilient -- having survived dramatic global climate change and Earth's most recent mass extinction event 66 million years ago, according to research published this week in the
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Sea butterflies and sea angels are pteropods, abundant, floating snails that spend their entire lives in the open ocean. A remarkable example of adaptation to life in the open ocean, these mesmerizing animals can have thin shells and a snail foot transformed into two wing-like structures that enable them to "fly" through the water.Sea butterflies have been a focus for global change research because they make their shells of aragonite, a form of calcium carbonate that is 50 percent more soluble than calcite, which other important open ocean organisms use to construct their shells. As their shells are susceptible to dissolving in more acidified ocean water, pteropods have been called "canaries in the coal mine," or sentinel species that signal the impact of ocean acidification.With some pteropods having thin shells and others having only partial or absent shells, such as the sea angels, their fossil record is patchy. Abundant pteropod fossils are only known from 56 million years ago onward and mostly represent the fully-shelled sea butterflies. These observations led to the notion that evolutionarily, pteropods are a relatively recent group of gastropods.An international team of researchers sampled 21 pteropod species across two ocean transects as part of the Atlantic Meridional Transect programme and collected information on 2,654 genes. Analyzing these data and key pteropod fossils, the scientists determined that the two major groups of pteropods, sea butterflies and sea angels, evolved in the early Cretaceous, about 139 million years ago."Hence, both groups are much older than previously thought and must have survived previous episodes of widespread ocean acidification, such as at the end of the Cretaceous, 66 million years ago, and the Paleocene-Eocene Thermal Maximum, 56 million years ago," said Peijnenburg.Knowing whether major groups of pteropods have been exposed to periods of high carbon dioxide is important as researchers attempt to predict how various marine species may respond to current and future global change."Although these results suggest that open ocean, shelled organisms have been more resilient to past ocean acidification than currently thought, it is unlikely that pteropods have experienced global change of the current magnitude and speed during their entire evolutionary history," said Erica Goetze, co-author and University of Hawai'i at M?noa oceanographer.It is still an open question whether marine organisms, particularly those that calcify, have the evolutionary resilience to adapt fast enough to an increasingly acidified ocean."Current rates of carbon release are at least an order of magnitude higher than we have seen for the past 66 million years," said Peijnenburg. Hence, she stressed the disclaimer "past performance is no guarantee of future results."
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Climate
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928090500.htm
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The testimony of trees: How volcanic eruptions shaped 2000 years of world history
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Researchers have shown that over the past two thousand years, volcanoes have played a larger role in natural temperature variability than previously thought, and their climatic effects may have contributed to past societal and economic change.
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The researchers, led by the University of Cambridge, used samples from more than 9000 living and dead trees to obtain a precise yearly record of summer temperatures in North America and Eurasia, dating back to the year 1 CE. This revealed colder and warmer periods that they then compared with records for very large volcanic eruptions as well as major historical events.Crucial to the accuracy of the dataset was the use of the same number of data points across the entire 2000 years. Previous reconstructions of climate over this extended period have been biased by over-representation of trees from more recent times.The results, reported in the journal Instead, the researchers say, the study contributes to our understanding of the natural causes and societal consequences of summer temperature changes over the past two thousand years."There is so much we can determine about past climate conditions from the information in tree rings, but we have far more information from newer trees than we do for trees which lived a thousand years or more ago," said Professor Ulf Büntgen from Cambridge's Department of Geography, the study's lead author. "Removing some of the data from the more recent past levels the playing field for the whole 2000-year period we're looking at, so in the end, we gain a more accurate understanding of natural versus anthropogenic climate change."Comparing the data from tree rings against evidence from ice cores, the researchers were able to identify the effect of past volcanic eruptions on summer temperatures.Large volcanic eruptions can lower global average temperatures by fractions of a degree Celsius, with strongest effects in parts of North America and Eurasia. The main factor is the amount of sulphur emitted during the eruption that reaches the stratosphere, where it forms minute particles that block some sunlight from reaching the surface. This can result in shorter growing seasons and cooler temperatures, that lead in turn to reduced harvests. Conversely, in periods when fewer large eruptions occurred, the Earth is able to absorb more heat from the Sun and temperatures rise."Some climate models assume that the effect of volcanoes is punctuated and short," said Büntgen. "However, if you look at the cumulative effect over a whole century, this effect can be much longer. In part, we can explain warm conditions during the 3rd, 10th and 11th centuries through a comparative lack of eruptions."Reconstructed summer temperatures in the 280s, 990s and 1020s, when volcanic forcing was low, were comparable to modern conditions until 2010.Compared with existing large-scale temperature reconstructions of the past 1200-2000 years, the study reveals a greater pre-industrial summer temperature variability, including strong evidence for the Late Antique Little Ice Age (LALIA) in the 6th and 7th centuries.Then, working with historians, the scientists found that relatively constant warmth during Roman and medieval periods, when large volcanic eruptions were less frequent, often coincided with societal prosperity and political stability in Europe and China. However, the periods characterised by more prolific volcanism often coincided with times of conflict and economic decline."Interpreting history is always challenging," said Dr Clive Oppenheimer, the lead volcanologist of the study. "So many factors come into play -- politics, economics, culture. But a big eruption that leads to widespread declines in grain production can hurt millions of people. Hunger can lead to famine, disease, conflict and migration. We see much evidence of this in the historical record."We knew that large eruptions could have these effects, especially when societies were already stressed, but I was surprised to see the opposite effect so clearly in our data -- that centuries with rather few eruptions had warmer summers than the long-term average."The new temperature reconstructions provide deeper insights into historical periods in which climactic changes, and their associated environmental responses, have had an outsized impact on human history. This has clear implications for our present and future. As climate change accelerates, extreme events, such as floods, drought, storms and wildfires, will become more frequent."Humans have no effect on whether or not a volcano erupts, but the warming trend we are seeing right now is certainly related to human activity," said Büntgen. "While nothing about the future is certain, we would do well to learn how climate change has affected human civilisation in the past."
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Climate
| 2,020 |
September 26, 2020
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https://www.sciencedaily.com/releases/2020/09/200926145151.htm
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Coldest Northern Hemisphere temps of minus 69.6 degress Celsius: Greenland, 1991
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Nearly 30 years after recording a temperature of minus 93.2 degrees Fahrenheit (minus 69.6 Celsius) in Greenland, the measurement has been verified by the World Meteorological Organization as the coldest recorded temperature in the Northern Hemisphere.
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The measurement was first recorded by a University of Wisconsin-Madison Antarctic Meteorological Research Center Automatic Weather Station in December 1991. An AWS is a standalone instrument suite developed by UW-Madison Space Science and Engineering Center and AMRC scientists and engineers to collect numerous environmental parameters such as air temperature, pressure, humidity, wind direction and speed. The information is then relayed via satellite back to SSEC in near real time.Over time, these data have come to provide a benchmark for understanding weather extremes and climate change."The more data you have, the more you can understand what's going on globally, and make important political and environmental decisions related to climate change," says George Weidner, emeritus researcher with the UW-Madison Department of Atmospheric and Oceanic Sciences. "It is also an important moment for the AWS systems in that their data are being accepted as official records."Weidner is the lead author on a new paper published in the In 2007, the WMO created an online archive of weather and climate extremes around the globe, helping to set benchmarks for future climate research. Other measurements include record high temperatures, wind speeds, and the impact of tropical cyclones, including the deadliest in history.Extreme measurements like that in Greenland undergo a rigorous review process to make sure they are accurate and there is agreement with other meteorological data and weather forecast models. Due to the quality and preservation of the AWS station data provided by the Antarctic Meteorological Research Center, the WMO was able to verify the 1991 temperature and log it as part of the official record.According to Weidner, this cold temperature was the result of several atmospheric conditions converging in a specific way.The Klinck field site, where the coldest temperature was measured, is located in the middle of Greenland at an elevation of 10,170 feet (3,100 meters). Extreme cold air temperatures can occur when there is little wind to disturb an area, accompanied by clear skies.In this case, the elevation and a splitting of the jet stream -- which usually flows over the Greenland ice sheet -- created a dead zone, allowing the already cold region to continue losing heat from the Earth. Similar conditions occur over Canada and result in the famed (or infamous) "polar vortex," which produces extreme cold that reaches the U.S.For more than 40 years, the network of more than 60 Automatic Weather Station sites has helped provide real-time data for scientists in extreme places like Antarctica and Greenland and has helped build a more complete picture of changes in Earth's climate. In March 2017, the WMO confirmed some of the warmest ever recorded temperatures in Antarctica and used data from AMRC's AWS network to help verify these measurements.This work is supported by the National Science Foundation.
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Climate
| 2,020 |
September 25, 2020
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https://www.sciencedaily.com/releases/2020/09/200925113351.htm
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Marine heatwaves are human-made
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A marine heatwave (ocean heatwave) is an extended period of time in which the water temperature in a particular ocean region is abnormally high. In recent years, heatwaves of this kind have caused considerable changes to the ecosystems in the open seas and at the coast. Their list of negative effects is long: Marine heatwaves can lead to increased mortality among birds, fish and marine mammals, they can trigger harmful algal blooms, and greatly reduce the supply of nutrients in the ocean. Heatwaves also lead to coral bleaching, trigger movements of fish communities to colder waters, and may contribute to the sharp decline of the polar icecaps.
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Researchers led by Bern-based marine scientist Charlotte Laufkötter have been investigating the question of how anthropogenic climate change has been affecting major marine heatwaves in recent decades. In a study recently published in the well-known scientific journal In its investigations, the Bern team studied satellite measurements of the sea surface temperature between 1981 and 2017. It was found that in the first decade of the study period, 27 major heatwaves occurred which lasted 32 days on average. They reached maximum temperatures of 4.8 degrees Celsius above the long-term average temperature. In the most recent decade to be analyzed, however, 172 major events occurred, lasting an average of 48 days and reaching peaks of 5.5 degrees above the long-term average temperature. The temperatures in the sea usually fluctuate only slightly. Week-long deviations of 5.5 degrees over an area of 1.5 million square kilometers -- an area 35 times the size of Switzerland -- present an extraordinary change to the living conditions of marine organisms.For the seven marine heatwaves with the greatest impact, researchers at the University of Bern carried out what is referred to as attribution studies. Statistical analyses and climate simulations are used to assess the extent to which anthropogenic climate change is responsible for the occurrence of individual extremes in the weather conditions or the climate. Attribution studies typically demonstrate how the frequency of the extremes has changed through human influence.According to the findings of the attribution studies, major marine heatwaves have become more than 20 times more frequent due to human influence. While they occurred every hundred or thousand years in the pre-industrial age, depending on the progress of global warming, in the future they are set to become the norm. If we are able to limit global warming to 1.5 degrees, heatwaves will occur once every decade or century. If temperatures rise by 3 degrees, however, extreme situations can be expected to occur in the world's oceans once per year or decade. "Ambitious climate goals are an absolute necessity for reducing the risk of unprecedented marine heatwaves," emphasizes Charlotte Laufkötter. "They are the only way to prevent the irreversible loss of some of the most valuable marine ecosystems."
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Climate
| 2,020 |
September 25, 2020
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https://www.sciencedaily.com/releases/2020/09/200925113344.htm
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Major wind-driven ocean currents are shifting toward the poles
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The severe droughts in the USA and Australia are the first sign that the tropics, and their warm temperatures, are apparently expanding in the wake of climate change. But until now, scientists have been unable to conclusively explain the reasons for this, because they were mostly focusing on atmospheric processes. Now, experts at the AWI have solved the puzzle: the alarming expansion of the tropics is not caused by processes in the atmosphere, but quite simply by warming subtropical ocean.
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Forest fires in Australia and California, droughts and water shortages in the Mediterranean -- in the last few years, events such as these have become more frequent. Researchers attribute this to the fact that the tropics, the warm region surrounding the Equator, appear to be expanding. And that leads to the affected areas becoming hotter and drier. According to the official definition, the tropics extend across the Equator between the latitudes of 23 degrees North and 23 degrees South. The central area is humid, with a great deal of precipitation, while the marginal regions in the north and south are hot and dry. As a result of climate change, however, for some time now the dry regions have been expanding northwards in the Northern Hemisphere -- as far as Southern California -- and southwards in the Southern Hemisphere.But up to now, climate researchers have had a problem. They couldn't conclusively explain this obvious expansion of the tropics using their climate models. The models simply didn't show the magnitude and the regional characteristic of the observed expansion. A team working with the physicists Hu Yang and Gerrit Lohmann at the Alfred Wegner Institute, Helmholtz Centre for Polar and Marine Research in Bremerhaven (AWI) has now discovered the likely cause. As the AWI experts report in the "Our simulations show that an enhanced warming over the subtropical ocean in both the Northern and Southern Hemispheres are the main drivers," says Hu Yang, the study's lead author. These subtropical warming patterns are generated by the dynamic of subtropical ocean gyres, measuring several hundreds of kilometres in diameter, which rotate slowly. These currents are especially well-known in the Pacific, because the majority of floating marine litter is concentrated in them. "Because the currents in the region bring together the surface warming water masses particularly intensely, it's easier for the subtropical ocean surface to accumulate warmth than in other regions -- and the same applies to plastic," says Lohmann. As a result of this warming of the subtropical ocean, the tropical warm ocean regions are expanding. According to his calculations, this phenomenon is the catalyst for the tropics expanding to the north and south. "Previous researchers had been taking an overly complicated approach to the problem, and assumed it was due to complex changes in the atmosphere. In reality, it's due to a relatively simple mechanism involving ocean currents."What led the experts to explore this avenue: data on ocean gyres that they happened to come across five years ago -- data on ocean temperatures and satellite-based data, freely available on databases. Both sources indicated that the gyres were becoming warmer and more powerful. "That's what led us to believe that they might be a decisive factor in the expansion of the tropics," explains Hu Yang.The AWI experts were right: their findings perfectly correspond to actual observations and the latest field data on tropical expansion. Just like in reality, their climate model shows that the tropics are now stretching farther to the north and south alike. In the Southern Hemisphere, the effect is even more pronounced, because the ocean takes up more of the overall area there than in the Northern Hemisphere.Yet when it comes to the question of whether the droughts in Australia, California and the Mediterranean are due to the expansion of the tropics, Gerrit Lohmann can't give a definitive answer. "When talking about climate change, it's always difficult to quantify the respective parameters with absolute certainty," he says. "However, we can safely assume that the ocean currents and expansion of the tropics make droughts and hurricanes more likely to occur."
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Climate
| 2,020 |
September 25, 2020
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https://www.sciencedaily.com/releases/2020/09/200924141455.htm
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Impact of climate change on rainforest elephants
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Experts from the University of Stirling, working closely with the Government of Gabon, have led an international study into the impact of climate change on Central Africa's rainforests and the threat posed to elephant populations in the region.
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Dr Emma Bush and Dr Robin Whytock, of the Faculty of Natural Sciences, along with Professors Kate Abernethy and Lee White, are lead authors of 'Long-term collapse in fruit availability threatens Central African forest megafauna' published in the journal The study found an 81% decline in fruit production between 1986 and 2018, alongside an 11% drop in the physical condition of fruit-dependent forest elephants since 2008.This means that, on average, elephants and other animals would have encountered ripe fruit on one in every 10 trees in the 1980s, but need to search more than 50 trees today.The region's climate has changed since the 1980s, becoming warmer and drier, and it is believed this may be behind the decline in rainforest fruit production. Mean temperature has increased by almost 1oC during the course of the study. Some tree species in Lopé National Park are dependent on a dip in temperature to trigger flowering but warmer temperatures may mean that this vital cue to producing fruit is being missed.Dr Emma Bush said: "The massive collapse in fruiting among more than 70 tree species studied at Lopé National Park, Gabon may be due to species missing the environmental cue to bear fruit, because of increased temperatures and less rainfall. Less fruit in the ecosystem will have huge impacts on forest dynamics such as seed dispersal, plant reproduction and food availability for wildlife such as forest elephants, chimpanzees, and gorillas."The University of Stirling is a pioneer in tropical ecology research, having established the Station d'Etudes des Gorilles et Chimpanzes (SEGC -- The Gorilla and Chimpanzee Research Station) with the Centre Internationale de Recherches Médicales de Franceville (CIRMF, The International Medical Research Centre in Franceville) in Lopé National Park, central Gabon, in 1983.This 37-year, on-going collaboration between the University and the Government of Gabon has generated a unique data set that allows researchers to monitor how the rainforests and wildlife of the Congo Basin are responding to climate change.Dr Robin Whytock said: "Large animals like forest elephants are already under severe pressure in Central Africa due to hunting, habitat loss and habitat degradation. If important protected areas like Lopé National Park in Gabon can no longer support them because there is not enough food, then we may see further population declines, jeopardising their survival in the long-term."We know that large bodied animals, like elephants, are disproportionately important for the healthy functioning of ecosystems and their loss could result in broad changes to forest systems and even reduce the amount of carbon stored there."Functioning tropical ecosystems are important for global climate regulation and global health. This research highlights how global climate change might be affecting plants and animals locally, through decreased forest food production. It also adds to the global body of evidence highlighting the ongoing biodiversity crisis and the consequences of rapid climatic change.Professor Lee White, Gabon's Minister of Water, Forest, Sea and Environment, and an Honorary Professor at the University of Stirling, said: "Long-term ecological research such as ours is unfortunately extremely rare in the tropics, and it is possible that similar processes are underway, but undetected, throughout the tropical rainforests of our planet."It is alarming that climate change may be resulting in forest elephants going hungry, and we need to seriously consider whether this is forcing elephants out of the forests to approach rural villages in search of food, resulting in an increase in crop raiding.
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Climate
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September 25, 2020
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https://www.sciencedaily.com/releases/2020/09/200925113616.htm
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Simpler models may be better for determining some climate risk
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Typically, computer models of climate become more and more complex as researchers strive to capture more details of our Earth's system, but according to a team of Penn State researchers, to assess risks, less complex models, with their ability to better sample uncertainties, may be a better choice.
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"There is a downside to the very detailed, very complex models we often strive for," said Casey Helgeson, assistant research professor, Earth and Environmental Systems Institute. "Sometimes the complexity of scientific tools constrains what we can learn through science. The choke point isn't necessarily at the knowledge going into a model, but at the processing."Climate risks are important to planners, builders, government officials and businesses. The probability of a potential event combined with the severity of the event can determine things like whether it makes sense to build in a given location.The researchers report online in Complex Earth systems models need a lot of supercomputer time to run. However, when looking at risk, uncertainty is an important element and researchers can only discover uncertainty through multiple runs of a computer model. Computer time is expensive."We need complex models to simulate the interactions between Earth system processes," said Vivek Srikrishnan, assistant research professor, Earth and Environmental Systems Institute. "We need simple models to quantify risks."According to Klaus Keller, professor of geosciences, multiple model runs are important because many events of concern such as floods are, fortunately, the exception, not what is expected. They happen in the tails of the distribution of possible outcomes. Learning about these tails requires many model runs.Simple models, while not returning the detailed, complex information of the latest complex model containing all the bells and whistles, can be run many times quickly, to provide a better estimate of the probability of rare events."One of the things we focus on are values embedded in the models and whether the knowledge being produced by those models provides decision makers with the knowledge they need to make the decisions that matter to them," said Nancy Tuana, DuPont/Class of 1949 Professor of Philosophy and Women's, Gender, and Sexuality Studies.Determining an appropriate model that can address the question and is still transparent is important."We want to obtain fundamental and useful insights," said Keller. "Using a simple model that allows us to better quantify risks can be more useful for decision-makers than using a complex model that makes it difficult to sample decision-relevant outcomes."Srikrishnan added, "We need to make sure there is an alignment between what researchers are producing and what is required for real-world decision making."The researchers understand that they need to make both the producers and users happy, but sometimes the questions being asked do not match the tools being used because of uncertainties and bottlenecks."We need to ask 'what do we need to know and how do we go about satisfying the needs of stakeholders and decision makers?'" said Tuana.The National Science Foundation through the Network for Sustainable Climate Risk Management supported this work.
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Climate
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September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924135350.htm
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Caribbean islands face loss of protection and biodiversity as seagrass loses terrain
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Tropical islands have an important ally when it comes to battling storms and sea-level rise: seagrass. During hurricane Irma, an extremely powerful Category 5 storm that hit the North Caribbean in 2017, NIOZ scientist Rebecca James witnessed how native seagrass meadows along the coast of Sint Maarten held their ground, reduced coastal erosion and lowered the chances of flooding. In the years of research during her PhD, she saw the pressures on this natural storm protection increasing. In her dissertation, The future of seagrass ecosystem services in a changing world, James warns that further loss of these green meadows will leave tropical islands vulnerable and will exacerbate the negative effects of climate change
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The flexible grass, that grows in shallow bays and lagoons throughout the Caribbean, is a natural wave dampener. As it sways back and forth, it removes energy from the waves, keeps the sand on the seafloor stable and, thereby, protects the beach against erosion. James: 'It is a great natural protector of beaches and reduces the need for human intervention, such as sand nourishments and seawalls.'Seagrass offers more than protection to the islands and its people. The underwater meadows form a rich environment in which marine life, from micro-organisms to large animals, thrive. In turn, this benefits the local fishing communities. James: 'In science, we call these ecosystem services.' And seagrass serves many. James: 'Through photosynthesis, seagrass removes COThe biggest threats come from human disturbance, invasive species and bad water quality on the coasts. James: 'Tourists flock to the Caribbean for the beautiful beaches and clear waters. Resorts, restaurants and bars have been built throughout the Caribbean to support tourism, however, often at the expense of the natural environment.' Dunes had to make way for hotels, seagrass -and seaweed were removed to create perfectly groomed beaches, feet trample the meadows, and boat anchors leave scars; physical damage that takes years to recover.A healthy seagrass ecosystem depends on healthy neighbours. And the grasses suffer under the damage done to nearby coral reefs or inland mangroves. James: 'Coral reefs, mangroves and seagrass meadows are vital for a healthy Caribbean Bay. The systems are strongly connected and benefit each other.' Animals move between the corals and seagrass meadows depending on their need for food or protection from predators or waves. Mangroves filter sediment that runs from the land into the ocean, improving water quality and clarity. James: 'With more people comes more wastewater, which reduces the water quality when there isn't sufficient water treatment.' Over the years, more and more mangroves had to make way for farming and housing. With little left behind to capture the sediment, the water in the bays turns cloudy and dirty.As the pressure on seagrass increases from different directions, the importance of an integrated approach to protection, conservation and restoration becomes clear. James: 'My more recent research shows that overgrazing by turtles and an invasive seagrass species (Halophila stipulacea) that is currently spreading around the Caribbean, reduce the coastal protection services. This example shows the importance to match conservation efforts of turtles with conservation of their habitats.'To mitigate the negative effects of climate change and protect the biodiversity in our oceans, there is a great need for the natural self-sustaining strategies that seagrass meadows provide. However, James warns that in ecosystems it is not that simple to get back what was once lost. James: 'Only 37% of seagrass restorations have survived. Projects like these take time, money and support from local communities and stakeholders. Working in coastal areas, waves and storms can undo hours of intensive restoration labour.'James urges that we need to act fast to improve the health of seagrass ecosystems. 'Only healthy ecosystems have a chance of withstanding the more extreme weather events, a rise in CO
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Climate
| 2,020 |
September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924114137.htm
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Newly identified 'landfalling droughts' originate over ocean
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Meteorologists track hurricanes over the oceans, forecasting where and when landfall might occur so residents can prepare for disaster before it strikes. What if they could do the same thing for droughts?
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Stanford scientists have now shown that may be possible in some instances -- the researchers have identified a new kind of "landfalling drought" that can potentially be predicted before it impacts people and ecosystems on land. They found that these droughts, which form over the ocean and then migrate landward, can cause larger and drier conditions than droughts that occur solely over the land. Of all the droughts affecting land areas worldwide from 1981 to 2018, roughly one in six were landfalling droughts, according to the study published Sept. 21 in "We normally don't think about droughts over the ocean -- it may even sound counterintuitive. But just as over land, there can be times where large regions in the ocean experience less rainfall than normal," said lead author Julio Herrera-Estrada, a research collaborator with Water in the West who conducted research for the study while he was a postdoctoral researcher at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth). "Finding that some droughts start offshore will hopefully motivate conversations about the benefits of monitoring and forecasting droughts beyond the continents."Droughts can harm or destroy crops, as well as impact water supplies, electricity generation, trade and ecosystem health. Historically, droughts have displaced millions of people and cost billions of dollars. Yet the climate processes that lead to drought are not fully understood, making accurate predictions difficult.In order to pinpoint the large-scale landfalling droughts that originated over the ocean, the researchers used an object tracking algorithm to identify and follow clusters of moisture deficits all over the world, going back decades in time. They found that the landfalling droughts grew about three times as fast as land-only droughts, and usually took several months to reach a continent."Not all of the droughts that cause damage to humans and ecosystems are going to be these landfalling droughts," said study senior author and climate scientist Noah Diffenbaugh, the Kara J. Foundation Professor at Stanford Earth. "But there is something about the droughts that start over the ocean that makes them more likely to turn into large, intense events."The researchers analyzed the physical processes of landfalling droughts in western North America, where a high frequency of them occur. They found that droughts that make landfall in the region have been associated with certain atmospheric pressure patterns that reduce moisture, similar to the "Ridiculously Resilient Ridge" pattern that was one of the primary causes of the 2012-2017 California Drought.The authors state that further analyses may reveal similar or new explanations for the landfalling droughts that they identified in other areas of the world, including Chile, Argentina, New Zealand and Eastern Australia."Our paper shows that landfalling droughts are a global phenomenon that affects every continent," Herrera-Estrada said. "There will definitely be a need for other studies to focus more on the physical processes relevant for each individual region."Because of the large humanitarian and economic impacts of severe droughts, the potential for forecasting landfalling droughts may warrant further investigation, according to the researchers."This is an important finding because these landfalling droughts are statistically likely to be larger and more severe relative to non-landfalling droughts," said Diffenbaugh, who is also the Kimmelman Family Senior Fellow at the Stanford Woods Institute for the Environment. "Because they usually take a number of months to migrate onto land, there is a potential that tracking moisture deficits over the ocean could provide advance warning to help protect against at least some of the most severe droughts."The research was supported by the U.S. Department of Energy and Stanford University.
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Climate
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September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924082713.htm
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Provide shady spots to protect butterflies from climate change
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Researchers have discovered significant variations in the ability of different UK butterfly species to maintain a suitable body temperature. Species that rely most on finding a suitably shady location to keep cool are at the greatest risk of population decline. The results predict how climate change might impact butterfly communities, and will inform conservation strategies to protect them.
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The results, published today in the More colourful larger species such as the Peacock (The study found that some butterfly species rely on finding a spot at a specific temperature within a landscape -- termed a 'microclimate' -- to control their body temperature. Air temperatures vary on a fine scale: a shaded patch of ground is cooler than one in full sun, for example. These 'thermal specialists', including Brown Argus (All butterflies are ectotherms: they can't generate their own body heat. The populations of two thirds of UK butterfly species are in decline: habitat loss and fragmentation, and more monotonous landscapes have removed many of the microclimates butterflies need to survive. Climate change is compounding the problem by causing more extreme weather events and greater fluctuations in temperature.Insects, including butterflies, pollinate around 85% of our food crops -- providing a vital service worth billions of pounds globally. Protecting a diverse range of species will provide long-term resilience: if numbers of one species fall there are others to fill the gaps. Insects are also an important food source for many other species, including birds."Butterfly species that aren't very good at controlling their temperature with small behavioural changes, but rely on choosing a micro-habitat at the right temperature, are likely to suffer the most from climate change and habitat loss," said Dr Andrew Bladon, a Postdoctoral Research Associate in the University of Cambridge's Department of Zoology, and first author of the report.He added: "We need to make landscapes more diverse to help conserve many of our butterfly species. Even within a garden lawn, patches of grass can be left to grow longer -- these areas will provide cooler, shady places for many species of butterfly. In nature reserves, some areas could be grazed or cut and others left standing. We also need to protect features that break up the monotony of farm landscapes, like hedgerows, ditches, and patches of woodland."Landscapes with a diversity of heights and features have a greater range of temperatures than flat, monotonous ones. This applies on scales from kilometres to centimetres: from hillsides to flower patches. Such structural diversity creates different microclimates that many butterflies use to regulate their temperature.The research involved catching nearly 4,000 wild butterflies in hand-held nets, and taking the temperature of each using a fine probe. The surrounding air temperature was measured, and for butterflies found perching on a plant, the air temperature at the perch was also taken. This indicated the degree to which butterflies were seeking out specific locations to control their body temperature. In total, 29 different butterfly species were recorded.The study reveals that butterflies are either thermal generalists or thermal specialists, and this does not always correspond with their current categorisations as either habitat generalists or specialists."As we plan conservation measures to address the effects of climate change, it will be important to understand not only the habitat requirements of different butterfly species, but also their temperature requirements," said Dr Ed Turner in the University Museum of Zoology, Cambridge, who led the work.He added: "With this new understanding of butterflies, we should be able to better manage habitats and landscapes to protect them, and in doing so we're probably also protecting other insects too."Over the past thirty years, many species of butterfly have expanded their range northwards, as more northerly places have become warmer due to climate change. The ranges of species adapted to cooler environments are shrinking. These trends have been tracked for butterfly populations as a whole, but no previous study has investigated how the individual butterflies that make up these populations are able to respond to small scale temperature changes.Bladon said: "I like to think of butterflies as the gateway drug. If we can get people involved in butterfly conservation, that's the first step to getting them to care about insects more broadly."
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Climate
| 2,020 |
September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924082706.htm
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5G wireless may lead to inaccurate weather forecasts
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Upcoming 5G wireless networks that will provide faster cell phone service may lead to inaccurate weather forecasts, according to a Rutgers study on a controversial issue that has created anxiety among meteorologists.
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"Our study -- the first of its kind that quantifies the effect of 5G on weather prediction error -- suggests that there is an impact on the accuracy of weather forecasts," said senior author Narayan B. Mandayam, a Distinguished Professor at the Wireless Information Network Laboratory (WINLAB), who also chairs the Department of Electrical and Computer Engineering in the School of Engineering at Rutgers University-New Brunswick.The peer-reviewed study was published this month at the 2020 IEEE 5G World Forum, sponsored by the Institute of Electrical and Electronics Engineers. Fifth-generation cellular wireless technology (5G) stems from new, smarter ways to use the higher (mmWave) frequencies for mobile communications. This technology will revolutionize internet communication and telecommunication. It has faster connection times, increases the number of devices that can connect to a network and will be more widely available over the next two to three years, according to IEEE.The Rutgers study used computer modeling to examine the impact of 5G "leakage" -- unintended radiation from a transmitter into an adjacent frequency band or channel -- on forecasting the deadly 2008 Super Tuesday Tornado Outbreak in the South and Midwest.The signals from the 5G frequency bands potentially could leak into the band used by weather sensors on satellites that measure the amount of water vapor in the atmosphere and affect weather forecasting and predictions. Meteorologists rely on satellites for the data needed to forecast weather.Based on modeling, 5G leakage power of -15 to -20 decibel Watts (a decibel Watt is a unit of power that describes the strength of radio waves) affected the accuracy of forecasting of precipitation (by up to 0.9 millimeters) during the tornado outbreak and temperatures near ground level (by up to 2.34 degrees Fahrenheit)."It can be argued that the magnitude of error found in our study is insignificant or significant, depending on whether you represent the 5G community or the meteorological community, respectively," Mandayam said. "One of our takeaways is that if we want leakage to be at levels preferred by the 5G community, we need to work on more detailed models as well as antenna technology, dynamic reallocation of spectrum resources and improved weather forecasting algorithms that can take into account 5G leakage."The lead author is Mohammad Yousefvand, a Rutgers electrical engineering doctoral student. Co-authors include Professor Chung-Tse Michael Wu in the Department of Electrical and Computer Engineering, Professor Ruo-Qian (Roger) Wang in the Department of Civil and Environmental Engineering and Joseph Brodie, director of atmospheric research in the Rutgers Center for Ocean Observing Leadership.
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Climate
| 2,020 |
September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924141605.htm
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Driven by climate, more frequent, severe wildfires in Cascade Range reshape forests
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In recent years -- and 2020 is no exception -- parts of the Pacific Northwest that are typically too wet to burn are experiencing more frequent, severe and larger wildfires due to changes in climate. New research from Portland State University found that while the increased wildfire activity is causing widespread changes in the structure and composition of these mid-to-high elevation forests, the new landscapes are also likely more resilient to projected upward trends in future fire activity and climate conditions.
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The study, led by PSU graduate student Sebastian Busby, examined temperate forests that burned expansively, severely and repeatedly between 2003 and 2015 in the central Cascade Range of Oregon and Washington. On Mt. Adams, these wildfires included the 2008 Cold Springs, 2012 Cascade Creek and 2015 Cougar Creek fires. On Mt. Jefferson, the wildfires included the 2003 Booth and Bear Butte Complex, 2007 Warm Springs Area Lightning Complex and 2014 Bear Butte 2 fires. Some areas Busby studied have burned again this summer as part of the Lionshead fire in the Mt. Jefferson area.Busby said that historically, wet and cool climate limited fire events in these humid forest environments to an interval of 50 to 200-plus years. But climate change has led to warmer winters, reduced mountain snowpack and longer, drier summers and fire seasons. The time between repeated wildfire events in this study was less than 12 years."These forests are drying out earlier in the year, making them more vulnerable to frequent, severe and larger wildfires," Busby said. "Because these forests have not historically burned very often, they're composed of high densities of tree species that are not well-adapted to frequent and very large severe fires."True firs were the dominant conifer tree species across the study areas, but post-fire tree regeneration was generally very poor due to a lack of live mature trees remaining after the fires to reseed the forest.The burned areas, however, did support the establishment of pines at a low density, which are functionally better adapted to fire. The findings suggest that in the near term, these forests may transition from a dense fir-dominated conifer forest into a patchy, low-density, pine-dominated forest that will likely lack the fuel connectivity conducive to crown fires. Busby said that while widespread forest composition change and forest cover loss may be alarming, the results indicate that the altered structure and composition are likely to be more resilient in the face of future fire and climate conditions, such as drought and heatwave events."From an ecological point of view, these reburned forests are going to have a greater abundance of tree species that are better adapted to fire and potentially have less flammable forest structure overall," he said. "Now, in these post-reburned forests that are growing in a warmer and drier world, it will be up to us to decide whether we let future fires burn or not."If forest managers and other stakeholders choose to suppress them, they risk returning these forests to their historical dense structures, which thrived in cool and wet climates. However, under ongoing warming conditions, this alternative might increase the likelihood of severe and expansive fires in the future, negatively impacting human life, property, and natural resources."Wildfires are a natural ecological process on these landscapes and have been for thousands of years," Busby said. "Wildfire can be a great catalyst for change, but that change doesn't have to be entirely negative. We must learn to co-exist with wildfires, use them effectively, and embrace the positive elements they bring to our regional forests and ecosystems."The findings are published in the journal
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Climate
| 2,020 |
September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924141603.htm
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Island-building in Southeast Asia created Earth's northern ice sheets
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The Greenland ice sheet owes its existence to the growth of an arc of islands in Southeast Asia -- stretching from Sumatra to New Guinea -- over the last 15 million years, a new study claims.
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According to an analysis by researchers at the University of California, Berkeley, UC Santa Barbara and a research institute in Toulouse, France, as the Australian continent pushed these volcanic islands out of the ocean, the rocks were exposed to rain mixed with carbon dioxide, which is acidic. Minerals within the rocks dissolved and washed with the carbon into the ocean, consuming enough carbon dioxide to cool the planet and allow for large ice sheets to form over North America and Northern Europe."You have the continental crust of Australia bulldozing into these volcanic islands, giving you really high mountains just south of the equator," said Nicholas Swanson-Hysell, associate professor of earth and planetary science at UC Berkeley and senior author of the study. "So, you have this big increase of land area that is quite steep, in a region where it's warm and wet and a lot of rock types that have the ability to naturally sequester carbon."Starting about 15 million years ago, this tropical mountain-building drew down carbon dioxide in the atmosphere, decreasing the strength of the greenhouse effect and cooling the planet. By about 3 million years ago, Earth's temperature was cool enough to allow snow and ice to remain through the summer and grow into huge ice sheets over the Northern Hemisphere, like that covering Greenland today.Once Northern Hemisphere ice sheets grew, other climate dynamics led to a cycle of glacial maxima and minima every 40,000 to 100,000 years. At the most recent glacial maximum, about 15,000 years ago, massive ice sheets covered most of Canada, the northern portions of the U.S., as well as Scandinavia and much of the British Isles."If it wasn't for the carbon sequestration that's happening in the Southeast Asian islands, we wouldn't have ended up with the climate that includes a Greenland ice sheet and these glacial and interglacial cycles," Swanson-Hysell said. "We wouldn't have crossed this atmospheric COThe periodic growth and decline of the northern ice sheets -- the cycle of glacial maxima and minima -- is likely postponed, due to human emissions that have increased carbon dioxide concentrations in the atmosphere."A process that took millions of years we have reversed in 100 years," Swanson-Hysell said. "Over the next tens to hundreds of thousands of years, geological processes in places like Southeast Asia will once again decrease COUC Berkeley doctoral student Yuem Park, Swanson-Hysell and their colleagues, including Francis Macdonald of UC Santa Barbara and Yves Goddéris of Géosciences Environnement Toulouse, will publish their findings this week in the journal Geologists have long speculated about the processes that periodically warm and cool the planet, occasionally covering the entire globe with ice and turning it into a so-called snowball Earth.Once scientists realized that, over the course of millions of years, tectonic processes move land masses around the planet like massive jigsaw puzzle pieces, they sought a connection between continental movements -- and collisions -- and ice ages. Cycles of Earth's orbit are responsible for the 40,000- or 100,000-year fluctuations in temperature that overlay the long-term warming and cooling.The rise of the Himalayas in Asia in the mid-latitudes over the past 50 million years has been a prime candidate for cooling and the start of a glacial climate after an extended geologic interval without ice sheets. A few years ago, however, Swanson-Hysell and Macdonald saw a correlation between mountain-building in tropical areas and the onset of time intervals with ice ages over the past 500 million years.In 2017, they proposed that a major ice age 445 million years ago was triggered by mountain- building in the tropics, and they followed that in 2019 with a more complete correlation of the last four time intervals of glacial climate and collisions between continents and tropical island arcs. They argue that the combination of increased exposure of rock with minerals that can sequester carbon and a plenitude of warm tropical rain is particularly effective in pulling carbon dioxide from the atmosphere.The process involves chemical dissolution of the rocks that consume carbon dioxide, which is then locked in carbonate minerals that form limestone rock in the ocean. The calcium within seashells that you find on the beach may have come out of a tropical mountain on the other side of the world, Swanson-Hysell said."We built up a new database of these types of mountain-building events and then reconstructed the latitude at which they happened," Swanson-Hysell said. "Then we saw, hey, there is a lot of cooling when there is a lot of this type of mountain being built in the tropics, which is the Southeast Asian setting. The Southeast Asian islands are the best analog for processes that we also see further in the past."For the current paper, Park, Swanson-Hysell and Macdonald teamed up with Goddéris to model more precisely what carbon dioxide levels would be with changes in the size of the Southeast Asian islands.The researchers first recreated the sizes of the islands as they grew over the last 15 million years, focusing primarily on the largest: Java, Sumatra, the Philippines, Sulawesi and New Guinea. They calculated that the area of the islands increased from 0.3 million square kilometers 15 million years ago to 2 million square kilometers today. UC Santa Barbara graduate student Eliel Anttila, who was an undergraduate student in earth and planetary science at UC Berkeley and is a co-author of the paper, contributed to this aspect of the research.They then used Godderis' GEOCLIM computer model to estimate how the growth of these islands altered carbon levels in the atmosphere. Together with UC Berkeley postdoctoral scholar Pierre Maffre, who recently obtained his Ph.D. in Godderis' lab, they updated the model to account for the variable effect of different rock types. The model is linked with a climate model in order to relate COThey found that the increase of land area along the southeast edge of the Pacific corresponded with global cooling, as reconstructed from oxygen isotope compositions in ocean sediments. The carbon dioxide levels inferred from the model also match some measurement-based estimates, though Swanson-Hysell admits that estimating COBased on their model, chemical weathering in the Southeast Asian islands alone diminished COWhile the threshold for Arctic glaciation is estimated to be about 280 ppm of carbon dioxide, the threshold for ice sheet formation at the South Pole is much higher: about 750 ppm. That's why the Antarctic ice sheets began forming much earlier, about 34 million years ago, than those in the Arctic.While the researchers' model doesn't allow them to isolate the climatic effects of the rise of the Himalayas, their Southeast Asian island scenario alone can account for the appearance of Northern Hemisphere ice sheets. They did explore the effect of volcanic events occurring around the same time, including massive lava flows, or flood basalts, such as those in Ethiopia and North America (Columbian traps). Though the weathering of such rocks has been proposed as an ice age trigger, the model shows that this activity played a minor role, compared to the rise of the Southeast Asian islands."These results highlight that the Earth's climate state is particularly sensitive to changes in tropical geography," the authors conclude.Swanson-Hysell credits the campus's France-Berkeley Fund for providing resources for an initial collaboration with Goddéris that led to a large collaborative grant from the National Science Foundation's (NSF's) Frontier Research in Earth Science program to further pursue the research resulting in this paper.The French-American team plans to model other past ice ages, including the one in the Ordovician period 445 million years ago that, in 2017, Swanson-Hysell and Macdonald proposed was triggered by a collision similar to that occurring today in the Southeast Asian islands. That collision took place during the first phase of Appalachian mountain-building, when the present-day eastern U.S. was located in the tropics.The research was supported by the France-Berkeley Fund and the NSF (1926001, 1925990).
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Climate
| 2,020 |
September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924101942.htm
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Urgent conservation needed for world's carnivorous plants
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New international research led by Curtin University has found approximately a quarter of carnivorous plant species across the world may be at risk of extinction due to global climate change, illegal poaching, and the clearing of land for agriculture, mining and development.
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Carnivorous plants are predatory plants which obtain some or most of their nutrients through specialised adaptations that allow them to attract, capture and kill their prey -- mainly flies and other small insects but occasionally even birds and small mammals. Well-known species of carnivorous plants include the Venus fly trap and pitcher plants.Lead researcher, restoration ecologist Dr Adam Cross from the School of Molecular and Life Sciences at Curtin University, said the loss of carnivorous plants would not only be devastating due to their captivating qualities, but could potentially have detrimental effects across ecosystems."Carnivorous plants are an iconic group of plants, and they are often involved in complex biological relationships with animals -- sometimes providing habitats for animals, or even relying upon animals to digest the prey they catch for them," Dr Cross said."Our research has found around 25 per cent of the world's carnivorous plants are at increasing risk of extinction. Australia is currently sixth in the world for harbouring the most Critically Endangered carnivorous plant species, behind Brazil, Indonesia, Philippines, Cuba and Thailand."Carnivorous plants usually occur in extremely sensitive habitats, and are often in areas experiencing direct conflict with human activities.During the team's research, each of the over 850 known carnivorous plant species was assessed for its exposure to threats such as residential and commercial development; agriculture and aquaculture activities; energy production and mining; transport development, such as land clearing for roads or trains; human exploitation, such as illegal collection; pollution; geological events; climate change; and severe weather."Globally speaking, the biggest threats to carnivorous plants are the result of agricultural practices and natural systems modifications, as well as continental scale environmental shifts caused by climate change," Dr Cross said."In Western Australia, which harbours more carnivorous plant species than any other place on Earth, the biggest threat remains the clearing of habitat to meet human needs, resulting hydrological changes, and of course the warming, drying climate trend that affects much of Australia."Research co-author Dr Andreas Fleischmann, from Botanische Staatssammlung Munich and Ludwig-Maximilians-University Munich, Germany, also noted that illegal poaching of carnivorous plants was a large problem."Noting their unique and fascinating features, some species of carnivorous plants are illegally collected from their natural habitats and sold to collectors. Poached plants of some species sell for hundreds of dollars," Dr Fleischmann said.Looking to the future, research co-author Dr Alastair Robinson from Royal Botanic Gardens Victoria, stressed the need for immediate action in order to save carnivorous plants species from extinction."Conservation initiatives must be established immediately to prevent these species being lost in the coming years and decades," Dr Robinson said."Urgent global action is required to reduce rates of habitat loss and land use change, particularly in already highly-cleared regions that are home to many threatened carnivorous plant species, including habitats in Western Australia, Brazil, southeast Asia and the United States of America."
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Climate
| 2,020 |
September 24, 2020
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https://www.sciencedaily.com/releases/2020/09/200924101934.htm
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One of the world's driest deserts is the focus of a new study on our changing climate
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Carbon, one of the main building blocks for all life on Earth, cycles among living organisms and the environment. This cycle, and how it works in one of the driest places on Earth, is the subject of a new study recently published in the journal Plant and Soil with lead author and Arizona State University (ASU) scientist, Heather Throop.
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While the natural carbon cycle should be balanced each year, with about as much carbon taken out of the atmosphere as is released back by natural processes, humans are upsetting this balance through carbon dioxide additions to the atmosphere, both through changing land use that releases carbon stored in soils and from burning fossil fuels.In an effort to understand what controls the release of carbon dioxide from soils in deserts, Throop and a team of university students from Namibia conducted field work in the Namib Desert, one of the world's driest regions that stretches more than 1,200 miles along the Atlantic coasts of Angola, Namibia, and South Africa.What Throop and her team ultimately determined from their research is that subtle differences in surface topography and erosion have big influences on microorganisms in the soil and these differences ultimately affect carbon cycling. Even in the driest places, they found signs of life influencing carbon cycling."The amount of carbon dioxide in the atmosphere affects our climate, so understanding what affects the release of carbon from soils is important predicting how climate will change in the future." says Throop, who is an associate professor in the School of Earth and Space Exploration and the School of Life Sciences.To conduct their analyses, the research team chose six locations that differed in yearly rainfall. At each site they carried out 48-hour sampling campaigns, working continuously day and night to collect data. At each location, the team analyzed the landscape structure and plants and selected representative locations to sample. Then, they simulated rainfall and used gas analyzers to measure carbon dioxide release from soils, to determine how carbon cycling responded as soils dried after the simulated rain."It's really an incredible amount of data to collect manually," says Throop. "And having a crew of dedicated and enthusiastic students made this work possible. Often for remote field work like this we just get a snapshot of what is happening at one or two sites or at a few points in time. It was exciting to be able to collect the data continuously for a few days and at six different sites."The students participating in this research came from the University of Namibia and the Namibia University of Science and Technology. They were each participating in the Summer Drylands Program, an intense research experience where students plan, execute, and report on an experiment within a short timeframe."The ability of technology to record soil carbon was outstanding," says co-author and student researcher Vimbai Marufu, who is now in graduate school at the Namibia University of Science and Technology. "What I treasure the most from the experience is what it means to work on an interdisciplinary team and the unexplainable satisfaction of being close to nature."And there are plans to continue additional fieldwork in the Namib Desert with a recent grant from the National Science Foundation to ASU. This grant will provide support for U.S. students to conduct research in the Namib Desert in collaboration with Namibian researchers. "We hope to use this work to help us in understanding how deserts respond to a changing climate," says Throop. "How biological processes function in the extreme dry of the Namib Desert will gives us clues about how relatively wet deserts will behave under drier conditions."
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Climate
| 2,020 |
September 23, 2020
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https://www.sciencedaily.com/releases/2020/09/200923164614.htm
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Amazonia racing toward tipping point, fueled by unregulated fires
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Amazonia is closer to a catastrophic ecological tipping point than any time in the last 100,000 years, and human activity is the cause.
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In a new paper published today in the Rainforests rely on high humidity and have no adaptation to withstand fire. Bush uses fossil pollen and charcoal recovered from lake sediments dating back thousands of years to track changes in vegetation and fire frequency through time. He has found that fires were almost unknown in Amazonia before the arrival of humans.Relatively small-scale disturbances caused by the first inhabitants of Amazonia over the last 10,000 years did not bring the system to a tipping point because it could recover from these minor events. But the modern effects of a warming climate and elevated drought risk -- both the product of anthropogenic climate change -- are combining with much larger-scale deforestation and burning in Amazonia to create the conditions where vast areas of rainforest could transition to savanna in a matter of decades."The immense biodiversity of the rainforest is at risk from fire," Bush said.One of the key points of the paper, "New and repeating tipping points: the interplay of fire, climate change and deforestation in Neotropical ecosystems," is that while no individual government can control climate change, fire can be regulated through policy. Almost all fires in Amazonia are set deliberately by people and have become much more frequent in the last two years, because of altered policy, than over the previous decade.Bush's data show that the tipping point is likely to be reached if temperatures rise by another 2 to 3 degrees Fahrenheit. Anthropogenic warming would bring those temperatures by the end of this century, but increased burning creates hotter, drier, less shaded landscapes that could hasten that transition."Warming alone could induce the tipping point by mid-century, but if the present policies that turn a blind eye to forest destruction aren't stopped, we could reach the tipping point much sooner," Bush said.He added, "Beyond the loss of wildlife, the cascading effects of losing Amazonian rainforest would alter rainfall across the hemisphere. This is not a remote problem, but one of global importance and critical significance to food security that should concern us all."
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Climate
| 2,020 |
September 23, 2020
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https://www.sciencedaily.com/releases/2020/09/200923164605.htm
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New model -- Antarctic ice loss expected to affect future climate change
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In a new climate modeling study that looked at the impacts of accelerated ice melt from the Antarctic Ice Sheet (AIS) on future climate, a team of climate scientists reports that future ice-sheet melt is expected to have significant effects on global climate.
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First author and graduate student Shaina Sadai at the University of Massachusetts Amherst, with Alan Condron of the Woods Hole Oceanographic Institution, Rob DeConto at UMass Amherst and David Pollard at Pennsylvania State University, present details this week in Their study predicts how future climate conditions could change under high- and low-greenhouse gas emissions scenarios, while accounting for accelerated melting of the AIS.Scientists have long recognized that future meltwater input from the Antarctic will affect the Southern Ocean and global climate, but ice-sheet processes are not now included in most state-of-the-art climate prediction simulations, Sadai says. She and colleagues report that their modeling with the added ice melt information reveals interacting processes.For this work, Sadai's task was to add accelerated AIS melting and icebergs into simulations of Earth's future climate. One important step was to include the details of where and when the meltwater will go into the ocean.She says, "We found that future melt water coming off Antarctica leads to huge amounts of thick sea ice around the continent. With higher greenhouse gas emissions, the ice sheet melts faster, which in turn leads to more freshwater flowing into the ocean and more sea ice production."All this additional meltwater and sea ice production dramatically slows the pace of future warming around Antarctica, the researchers report -- seemingly welcome news. And remarkably, the climate impacts are not just restricted to the Antarctic. Condron, previously at UMass Amherst, points out that the cooling effects are felt worldwide.But ,he adds, "All that said, it's important to note that this is not a global 'cooling' scenario -- average global temperatures would still be roughly 3 degrees Celsius warmer than today due to human greenhouse gas emissions, even with the cooling effects of this melt water on climate."That is not the end of the story. Even though atmospheric warming slows, the deep sea waters around Antarctica actually warm faster in their model. This is because, Condron explains, the new sea ice stops heat from escaping from the deeper waters to the atmosphere. "The subsurface ocean waters warm by as much as one degree Celsius, which can increase melting below parts of the ice sheet. This could make the ice sheet more unstable and accelerate rates of sea level rise beyond current projections."Overall, Sadai says, "Our results demonstrate a need to accurately account for meltwater input from ice sheets if we are to make confident climate predictions." She emphasizes that the delayed future warming they found in the new simulations may sound like good news, but it is important to keep in mind that serious warming and sea level rise will still occur with unabated greenhouse gas emissions, which will affect coastal communities and ecosystems worldwide.DeConto and Pollard add that the future stability of the AIS and future sea-level rise will be governed by which process wins out -- ocean warming or atmospheric cooling. Answering this question is the target of the team's ongoing research.
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Climate
| 2,020 |
September 23, 2020
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https://www.sciencedaily.com/releases/2020/09/200923124730.htm
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Uncovering new understanding of Earth's carbon cycle
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A new study led by a University of Alberta PhD student -- and published in Nature -- is examining the Earth's carbon cycle in new depth, using diamonds as breadcrumbs of insight into some of Earth's deepest geologic mechanisms.
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"Geologists have recently come to the realization that some of the largest, most valuable diamonds are from the deepest portions of our planet," said Margo Regier, PhD student in the Department of Earth and Atmospheric Sciences under the supervision of Graham Pearson and Thomas Stachel. "While we are not yet certain why diamonds can grow to larger sizes at these depths, we propose a model where these 'superdeep' diamonds crystallize from carbon-rich magmas, which may be critical for them to grow to their large sizes."Beyond their beauty and industrial applications, diamonds provide unique windows into the deep Earth, allowing scientists to examine the transport of carbon through the mantle."The vast majority of Earth's carbon is actually stored in its silicate mantle, not in the atmosphere," Regier explained. "If we are to fully understand Earth's whole carbon cycle then we need to understand this vast reservoir of carbon deep underground."The study revealed that the carbon-rich oceanic crust that sinks into the deep mantle releases most of its carbon before it gets to the deepest portion of the mantle. This means that most carbon is recycled back to the surface and only small amounts of carbon will be stored in the deep mantle -- with significant implications for how scientists understand the Earth's carbon cycle. The mechanism is important to understand for a number of reasons, as Regier explained."The movement of carbon between the surface and mantle affects Earth's climate, the composition of its atmosphere, and the production of magma from volcanoes," said Regier. "We do not yet understand if this carbon cycle has changed over time, nor do we know how much carbon is stored in the deepest parts of our planet. If we want to understand why our planet has evolved into its habitable state it is today and how the surfaces and atmospheres of other planets may be shaped by their interior processes, we need to better understand these variables."
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Climate
| 2,020 |
September 23, 2020
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https://www.sciencedaily.com/releases/2020/09/200923124706.htm
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Stability check on Antarctica reveals high risk for long-term sea-level rise
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The warmer it gets, the faster Antarctica loses ice -- and much of it will then be gone forever. Consequences for the world's coastal cities and cultural heritage sites would be detrimental, from London to Mumbai, and from New York to Shanghai. That's what a team of researchers from the Potsdam Institute for Climate Impact Research, Potsdam University and New York's Columbia University has found out in their new study, published in
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"Antarctica holds more than half of Earth's fresh water, frozen in a vast ice-sheet which is nearly 5 kilometers thick," explains Ricarda Winkelmann, researcher at the Potsdam Institute for Climate Impact Research (PIK) and University of Potsdam, and corresponding author of the study. "As the surrounding ocean water and atmosphere warm due to human greenhouse-gas emissions, the white cap on the South Pole loses mass and eventually becomes unstable. Because of its sheer magnitude, Antarctica's potential for sea-level contribution is enormous: We find that already at 2 degrees of warming, melting and the accelerated ice flow into the ocean will, eventually, entail 2.5 meters of global sea level rise just from Antarctica alone. At 4 degrees, it will be 6.5 meters and at 6 degrees almost 12 meters if these temperature levels would be sustained long enough."The paper's title refers to the complex physical phenomenon of hysteresis. In this case, that translates into irreversibility. Anders Levermann, co-author and researcher at PIK and Columbia University describes: "Antarctica is basically our ultimate heritage from an earlier time in Earth's history. It's been around for roughly 34 million years. Now our simulations show that once it's melted, it does not regrow to its initial state even if temperatures eventually sank again. Indeed, temperatures would have to go back to pre-industrial levels to allow its full recovery -- a highly unlikely scenario. In other words: What we lose of Antarctica now, is lost forever."The reasons behind this irreversibility are self-enforcing mechanisms in the ice sheets' behavior under warming conditions. Co-author Torsten Albrecht lays out: "In West Antarctica for instance, the main driver of ice loss is warm ocean water leading to higher melting underneath the ice shelves, which in turn can destabilize the grounded ice sheet. That makes glaciers the size of Florida slide into the ocean. Once temperatures cross the threshold of six degrees above pre-industrial levels, effects from the ice surface become more dominant: As the gigantic mountains of ice slowly sink to lower heights where the air is warmer, this leads to more melt at the ice surface -- just as we observe in Greenland."Ice loss and melting have accelerated significantly over the last decades in Antarctica. The authors however have explicitly not addressed the question of time scale in their work, but rather assess the critical warming levels at which parts of the Antarctic Ice Sheet become unstable. Winkelmann explains this approach: "In the end, it is our burning of coal and oil that determines ongoing and future greenhouse-gas emissions and therefore, if and when critical temperature thresholds in Antarctica are crossed. And even if the ice loss happens on long time scales, the respective carbon dioxide levels can already be reached in the near future. We decide now whether we manage to halt the warming. So Antarctica's fate really lies in our hands -- and with it that of our cities and cultural sites across the globe, from Rio de Janeiro's Copacabana to Sydney's Opera House. Thus, this study really is another exclamation mark behind the importance of the Paris Climate Accord: Keep global warming below two degrees."Levermann adds: "If we give up the Paris Agreement, we give up Hamburg, Tokyo and New York."
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Climate
| 2,020 |
September 23, 2020
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https://www.sciencedaily.com/releases/2020/09/200923124642.htm
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Some polar bears in far north are getting short-term benefit from thinning ice
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A small subpopulation of polar bears lives on what used to be thick, multiyear sea ice far above the Arctic Circle. The roughly 300 to 350 bears in Kane Basin, a frigid channel between Canada's Ellesmere Island and Greenland, make up about 1-2% of the world's polar bears.
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New research shows that Kane Basin polar bears are doing better, on average, in recent years than they were in the 1990s. The study, published Sept. 23 in "We find that a small number of the world's polar bears that live in multiyear ice regions are temporarily benefiting from climate change," said lead author Kristin Laidre, a polar scientist at the University of Washington Applied Physics Laboratory's Polar Science Center.If greenhouse gases continue to build up in the atmosphere and the climate keeps warming, within decades these polar bears will likely face the same fate as their southern neighbors already suffering from declining sea ice."The duration of these benefits is unknown. Under unmitigated climate change, we expect the Kane Basin bears to run into the same situation as polar bears in the south -- it's just going to happen later," Laidre said. "They'll be one of the last subpopulations that will be negatively affected by climate change."All of the world's 19 polar bear subpopulations, including Kane Basin, are experiencing a shorter on-ice hunting season, according to a 2016 study led by Laidre. This makes it hard for the animals, that can weigh more than 1,200 pounds as adults, to meet their nutritional needs. Polar bears venture out on sea ice to catch seals. In summer when the sea ice melts, the polar bears fast on land.Laidre led a recent study showing that in the Baffin Bay polar bear subpopulation, which includes about 2,800 bears living just south of Kane Basin, adult females are thinner and are having fewer cubs as the summer open-water season -- when they must fast on land -- grows longer."Kane Basin is losing its multiyear ice, too, but that doesn't have the same effect on the polar bears' ability to hunt," Laidre said. "Multiyear ice becomes annual ice, whereas annual ice becomes open water, which is not good for polar bears."The new paper looked at Kane Basin bears using satellite tracking data and direct physical measurements to compare from 1993 to 1997 with a more recent period, from 2012 to 2016. The body condition, or fatness, improved for all ages of males and females. The average number of cubs per litter, another measure of the animals' overall health, was unchanged.Satellite tags showed the Kane Basin polar bears traveled across larger areas in recent years, covering twice as much distance and ranging farther from their home territory."They now have to move over larger areas," Laidre said. "The region is transitioning into this annual sea ice that is more productive but also more dynamic and broken up."Observations show a profound shift in the sea ice in Kane Basin between the two study periods. In the 1990s, about half the area was covered in multiyear ice in the peak of summer, while in the 2010s the region was almost completely annual ice, which melts to open water in summer.Even though there's now more open water, the marine ecosystem has become more productive. Annual sea ice allows more sunlight through, so more algae grow, which supports more fish and in turn attracts seals."Two decades ago, scientists hypothesized that climate change could temporarily benefit polar bears in multiyear ice regions over the short term, and our observations support that," Laidre said.The subpopulation on the other side of Ellesmere Island, in Canada's Norwegian Bay, could be in a similar situation, she said, though no data exist for those animals.If conditions continue to warm these northernmost polar bears will likely face the same fate as their southern neighbors. Kane Basin polar bears have only much deeper water to turn to farther north."It's important not to jump to conclusions and suggest that the High Arctic, which historically was covered by multiyear sea ice, is going to turn into a haven for polar bears," said Laidre, who is also an associate professor in the UW School of Aquatic and Fishery Sciences. "The Arctic Ocean around the North Pole is basically an abyss, with very deep waters that will never be as productive as the shallower waters to the south where most polar bears live."So we are talking about temporary benefits in a limited area and to a very small number of bears."
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Climate
| 2,020 |
September 23, 2020
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https://www.sciencedaily.com/releases/2020/09/200923124612.htm
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Generational shifts help migratory bats keep pace with global warming
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Many animal species are currently changing their distribution range owing to global warming. The underlying mechanisms are still little known, especially in mammals. An international team of scientists led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) has now demonstrated that in the common noctule bat, one of the largest European bat species, the colonization of hibernacula progresses from lower to higher latitudes over successive generations of young animals -- especially first-year males. Because of their relatively high reproduction rate and the long-distance dispersal of male juveniles, it is probably relatively easy for common noctules to adjust to global warming. For species with lower reproduction rates and a limited migratory potential of the young -- the majority of European bat species -- the future might not look as favourable when facing continuing global warming. The paper was published in the scientific journal
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The rapid pace of global warming is forcing animals to adjust their lives to ensure their survival and successful reproduction. Highly mobile species such as migratory bats could potentially shift their summer and wintering habitats to higher or lower latitudes according to how the regional climate is changing. This flexibility could enable migratory bats to stay within ideal conditions for reproducing and rearing of young or for hibernation. For example, in recent years common noctule bats have shifted their wintering area further north. Is this shift in the wintering range the consequence of adult bats moving further north for hibernation year after year, or are these shifts done by juvenile bats from successive generations? Scientists of the Leibniz-IZW and partners from the Ukraine -- the "Bat Rehabilitation Center of Feldman Ecopark" and the "Ukrainian Independent Ecology Institute" -- addressed this question in a long-term study."We showed that the northwards move of the hibernation area of the common noctule occurs over several generations of juveniles," says Christian Voigt, head of the Department of Evolutionary Ecology at Leibniz-IZW. "Especially young males, which usually migrate further from their birthplace than young females, are leading the way when colonising new hibernacula." Since common noctules have a short life span, a high reproduction rate and can disperse over long distances, they may be able to adjust relatively quickly to global warming, even if the wintering area only successively changes from generation to generation.The investigation was carried out in the city of Kharkiv in northern Ukraine. Maternity colonies of common noctule females were long recorded north of the Kharkiv area, with hibernating animals moving to areas well south of Kharkiv. Then, 30 years ago the first individuals were encountered who hibernated further north close to Kharkiv, with increasing numbers of hibernating bats nearby since then. Over a ten-year period, the scientists collected data on the age and sex of almost 3,400 individuals. These data showed that young males dominated the early phase of colonisation of the new hibernation area. Gradually, the ratio of males to females and of young to adult animals became more balanced. "We also investigated the region of origin of the hibernating common noctules by analysing stable hydrogen isotopes in the fur keratin," says Kseniia Kravchenko from Leibniz-IZW, the first author of the paper. "The data of nearly 400 animals revealed that the number of long-distance migrants decreased in both females and males across all age groups." This showed that in the early years of colonisation the hibernation population originated from summer quarters in the far north. More recently, the "local" population with summer quarters nearby, who previously had flown further south for hibernation, increasingly used the same area as their summer quarters for reproduction and for wintering.The rapid generational shift and the high dispersal capacity of young males seem to be an evolutionary advantage of common noctule bats in times of climate change, the authors conclude. "Mammal species with higher life expectancies, lower reproductive rate and lower dispersal capacity may have a much harder time in keeping up with the pace of global warming," suspect Kravchenko and Voigt. "If the distribution areas of these species only shift from generation to generation, the pace may be too slow and there is a chance that they will become extinct if global warming continues at the current high pace." Further research will be necessary to understand these mechanisms of spatial adjustment to climate change in other mammalian species.
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Climate
| 2,020 |
September 22, 2020
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https://www.sciencedaily.com/releases/2020/09/200922135742.htm
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Warming temperatures are driving Arctic greening
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As Arctic summers warm, Earth's northern landscapes are changing. Using satellite images to track global tundra ecosystems over decades, a new study found the region has become greener, as warmer air and soil temperatures lead to increased plant growth.
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"The Arctic tundra is one of the coldest biomes on Earth, and it's also one of the most rapidly warming," said Logan Berner, a global change ecologist with Northern Arizona University in Flagstaff, who led the recent research. "This Arctic greening we see is really a bellwether of global climatic change -- it's a biome-scale response to rising air temperatures."The study, published this week in When the tundra vegetation changes, it impacts not only the wildlife that depend on certain plants, but also the people who live in the region and depend on local ecosystems for food. While active plants will absorb more carbon from the atmosphere, the warming temperatures could also be thawing permafrost, thereby releasing greenhouse gasses. The research is part of NASA's Arctic Boreal Vulnerability Experiment (ABoVE), which aims to better understand how ecosystems are responding in these warming environments and the broader social implications.Berner and his colleagues used the Landsat data and additional calculations to estimate the peak greenness for a given year for each of 50,000 randomly selected sites across the tundra. Between 1985 and 2016, about 38% of the tundra sites across Alaska, Canada, and western Eurasia showed greening. Only 3% showed the opposite browning effect, which would mean fewer actively growing plants. To include eastern Eurasian sites, they compared data starting in 2000, when Landsat satellites began regularly collecting images of that region. With this global view, 22% of sites greened between 2000 and 2016, while 4% browned."Whether it's since 1985 or 2000, we see this greening of the Arctic evident in the Landsat record," Berner said. "And we see this biome-scale greening at the same time and over the same period as we see really rapid increases in summer air temperatures."The researchers compared these greening patterns with other factors, and found that it's also associated with higher soil temperatures and higher soil moisture. They confirmed these findings with plant growth measurements from field sites around the Arctic."Landsat is key for these kinds of measurements because it gathers data on a much finer scale than what was previously used," said Scott Goetz, a professor at Northern Arizona University who also worked on the study and leads the ABoVE Science Team. This allows the researchers to investigate what is driving the changes to the tundra. "There's a lot of microscale variability in the Arctic, so it's important to work at finer resolution while also having a long data record," Goetz said. "That's why Landsat is so valuable."
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Climate
| 2,020 |
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