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September 22, 2020
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https://www.sciencedaily.com/releases/2020/09/200922112304.htm
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Evaporation critical to coronavirus transmission as weather changes
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As COVID-19 cases continue to rise worldwide, it is increasingly urgent to understand how climate impacts the continued spread of the coronavirus, particularly as winter virus infections are more common and countries in the northern hemisphere will soon see cooler temperatures.
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In a paper in "Suppose we have a better understanding of the evaporation and its relation to climate effects. In that case, we can more accurately predict the virus concentration and better determine its viability or the potential for virus survival," said Dimitris Drikakis, one of the authors.Despite the importance of airborne droplet transmission, research regarding heat and mass transfer around and within respiratory droplets containing the virus has been scarce.To address the challenge, the researchers developed theoretical correlations for the unsteady evaporation of coronavirus-contaminated saliva droplets. They implemented the theory in an advanced computational fluid dynamics platform and studied the effects of weather conditions on airborne virus transmission."We found high temperature and low relative humidity lead to high evaporation rates of saliva-contaminated droplets, thus significantly reducing the virus viability," said co-author Talib Dbouk.Additionally, the researchers observed the travel distance and concentration of the droplet cloud continued to be significant, even at high temperatures if the relative humidity is high. The wind speed is another crucial factor that might alter all the rules for the social distancing guidelines.These findings help explain why the pandemic increased during July in different crowded cities around the world, such as Delhi, which experienced both high temperatures and high relative humidity. It also provides a crucial alert for the possibility of a second wave of the pandemic in the coming autumn and winter seasons, where low temperatures and high wind speeds will increase airborne virus survival and transmission.This study adds to the growing body of research that reinforces the importance of social distancing and the use of face masks to prevent full virus spread. The results reveal the importance of weather conditions in the virus's viability, which can help guide the design of measures in both indoor and outdoor environments, to reduce airborne virus transmission in private and public spaces.
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Climate
| 2,020 |
September 22, 2020
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https://www.sciencedaily.com/releases/2020/09/200922112243.htm
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Forest margins may be more resilient to climate change than previously thought
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A warming climate and more frequent wildfires do not necessarily mean the western United States will see the forest loss that many scientists expect. Dry forest margins may be more resilient to climate change than previously thought if managed appropriately, according to Penn State researchers.
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"The basic narrative is it's just a matter of time before we lose these dry, low elevation forests," said Lucas Harris, a postdoctoral scholar who worked on the project as part of his doctoral dissertation. "There's increasing evidence that once disturbances like drought or wildfire remove the canopy and shrub cover in these dry forests, the trees have trouble coming back. On the other hand, there's growing evidence that there's a lot of spatial variability in how resilient these forests are to disturbances and climate change."The researchers studied forest regeneration at four sites that had experienced wildfires in the eastern Sierra Nevada Mountains in California. The sites sit at the forest margin, a drier area where forest meets sagebrush grassland. These dry forest margins may be the most vulnerable to climate change-driven forest loss, according to the researchers.Large fires in the area tend to consume the forest starting from the steppe margin then sweeping up the mountain, said Alan Taylor, professor of geography and ecology who has worked in the area for decades."You wouldn't see forest anymore over 10 or 20 years, and it seemed like the lower forest margin was getting pushed way up in elevation because it's so dry near the sagebrush boundary," Taylor said. "My research group wanted to look at this in detail because no one had actually done it."Harris and Taylor's research team measured tree diameters and litter depth, counted the number of seedlings and saplings and identified tree species at the research sites. They also quantified fire severity, the amount of moisture available for plant growth and water deficit, an indicator of drought intensity. They then fed the data into five models to see how the probability for tree regeneration varied based on fire severity, climate and location, and remaining vegetation and canopy cover. They report their results today (Sept. 21) in The researchers found that 50% of the plots at the sites showed signs of tree regeneration, and water balance projections through the end of the current century indicate that there will be enough moisture available to support tree seedlings. The key is to prevent severe fire disturbances through proper management, according to the researchers, because tree regeneration was strongly associated with mature trees that survived fires."In these marginal or dry forest areas, management approaches like prescribed burning or fuel treatments that thin the forest can prevent the severe fires that would push this ecosystem to a non-forest condition," said Taylor, who also holds an appointment in the Earth and Environmental Systems Institute. "The study suggests that these low-severity disturbances could actually create very resilient conditions in places where most people have been suggesting that we'll see forest loss."The researchers also noticed a shift in tree composition from fire-resistant yellow pines to less fire-resistant but more drought-resistant species like pinyon pine. They attributed the shift to drying and fire exclusion policies in effect over the last century."The shift could be beneficial if the species moving in is better suited to present and near-future climates," said Harris. "However, it could be dangerous if a bunch of fire-sensitive species move into a place and then it all burns up. Many trees would die, and we could see lasting forest loss."California's climate is projected to warm, but many climate models also forecast an average increase in winter precipitation, especially in the northern part of the state and in the mountains, continued Harris."On the one hand, you have greater drought intensity for sure, but also you're going to have these wetter periods where there's more moisture available for tree growth in the spring and maybe into the early summer," he said. "So if the trees are able to survive that drought stress and take advantage of the additional moisture present in some years, they might be able to maintain or even expand their distribution."This forest system is important for recreation, carbon storage, biodiversity and wildlife habitat, said Taylor. It also comprises part of the western side of the Great Basin, the largest area of contiguous watersheds that do not empty into an ocean in North America."There's not much forest in the Great Basin, which is a huge area of sagebrush grassland in Utah, Idaho, Oregon, Nevada and Arizona," Taylor said. "So the forests of the eastern Sierra Nevada Mountains represent a significant component of the forest found in that system."The National Science Foundation and Penn State, through a Center for Landscape Dynamics research award and a Ruby S. Miller Graduate Student Fellowship, funded this study. Marilyn Fogel, emerita professor in Earth and environmental sciences, University of California, Riverside, provided support for an undergraduate student conducting field work on the project.
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Climate
| 2,020 |
September 22, 2020
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https://www.sciencedaily.com/releases/2020/09/200922112232.htm
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Global analysis of how effective and topographic catchment areas differ
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Topographically sketched catchment areas are a spatial unit based on the shapes of the earth's surface. They show how human activities and climate change influence the available quantities of water. Knowledge of these units is fundamental to sustainable water management. However, due to underground connections, some catchment areas accumulate water from areas beyond their topographic boundaries, while others are effectively much smaller than their surface topography would suggest. Currently, most hydrological modelling strategies do not take these groundwater connections into account, but assume that the catchments are independent of their surroundings. For this reason, Dr. Yan Liu and Assistant Professor Dr. Andreas Hartmann from the Chair of Hydrological Modeling and Water Resources at the University of Freiburg, together with a team of researchers from the University of Bristol in England and Princeton University in the US, have introduced the Effective Catchment Index (ECI). Using this new metric, they were able to determine how topographic and actual catchment areas differ when analyzing a global data set. The team recently published the results in the journal
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Using the ECI, the team led by Liu and Hartmann was able to demonstrate that the assumption of a closed water balance, i.e. that the level of a river changes only through precipitation and evaporation from its topographic area, for example, does not apply to a considerable number of catchments around the world. Every third catchment studied has an effective catchment area that is even greater than twice or less than half its topographical area. The scientists recognized that these areas influence or are influenced outside their topographical boundaries by water management activities such as pumping groundwater and, for example, deforestation or reforestation.With their analysis, the researchers show that the ECI they have redefined is suitable for investigating how drought can spread across topographical boundaries as a result of water exchange. It can also be used in the analysis of the effects of climate and land use changes on cross-boundary water exchange. "This is how we have seen where we need to further investigate underground networks across topographical boundaries in order to support sustainable water management," says Hartmann.
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Climate
| 2,020 |
September 22, 2020
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https://www.sciencedaily.com/releases/2020/09/200922083910.htm
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New freshwater database tells water quality story for 12K lakes globally
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Although less than one per cent of all water in the world is freshwater, it is what we drink and use for agriculture. In other words, it's vital to human survival. York University researchers have just created a publicly available water quality database for close to 12,000 freshwater lakes globally -- almost half of the world's freshwater supply -- that will help scientists monitor and manage the health of these lakes.
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The study, led by Faculty of Science Postdoctoral Fellow Alessandro Filazzola and Master's student Octavia Mahdiyan, collected data for lakes in 72 countries, from Antarctica to the United States and Canada. Hundreds of the lakes are in Ontario."The database can be used by scientists to answer questions about what lakes or regions may be faring worse than others, how water quality has changed over the years and which environmental stressors are most important in driving changes in water quality," says Filazzola.The team included a host of graduate and undergraduate students working in the laboratory of Associate Professor Sapna Sharma in addition to a collaboration with Assistant Professor Derek Gray of Wilfrid Laurier University, Associate Professor Catherine O'Reilly of Illinois State University and York University Associate Professor Roberto Quinlan.The researchers reviewed 3,322 studies from as far back as the 1950s along with online data repositories to collect data on chlorophyll levels, a commonly used marker to determine lake and ecosystem health. Chlorophyll is a predictor of the amount of vegetation and algae in lakes, known as primary production, including invasive species such as milfoil."Human activity, climate warming, agricultural, urban runoff and phosphorus from land use can all increase the level of chlorophyll in lakes. The primary production is most represented by the amount of chlorophyll in the lake, which has a cascading impact on the phytoplankton that eat the algae and the fish that eat the phytoplankton and the fish that eat those fish," says Filazzola. "If the chlorophyll is too low, it can have cascading negative effects on the entire ecosystem, while too much can cause an abundance of algae growth, which is not always good."Warming summer temperatures and increased solar radiation from decreased cloud cover in the northern hemisphere also contributes to an increase in chlorophyll, while more storm events caused by climate change contribute to degraded water quality, says Sharma. "Agricultural areas and urban watersheds are more associated with degraded water quality conditions because of the amount of nutrients input into these lakes."The researchers also gathered data on phosphorus and nitrogen levels -- often a predictor of chlorophyll -- as well as lake characteristics, land use variables, and climate data for each lake. Freshwater lakes are particularly vulnerable to changes in nutrient levels, climate, land use and pollution."In addition to drinking water, freshwater is important for transportation, agriculture, and recreation, and provides habitats for more than 100,000 species of invertebrates, insects, animals and plants," says Sharma. "The database can be used to improve our understanding of how chlorophyll levels respond to global environmental change and it provides baseline comparisons for environmental managers responsible for maintaining water quality in lakes."The researchers started looking only at Ontario lakes, but quickly expanded it globally as although there are thousands of lakes in Ontario a lot of the data is not as readily available as it is in other regions of the world."The creation of this database is a feat typically only accomplished by very large teams with millions of dollars, not by a single lab with a few small grants, which is why I am especially proud of this research," says Sharma.
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Climate
| 2,020 |
September 21, 2020
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https://www.sciencedaily.com/releases/2020/09/200921170507.htm
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40% of O'ahu, Hawai'i beaches could be lost by mid-century
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The reactive and piecemeal approach historically used to manage beaches in Hawai'i has failed to protect them. If policies are not changed, as much as 40% of all beaches on O'ahu, Hawai'i could be lost before mid-century, according to a new study by researchers in the Coastal Geology Group at the University of Hawai'i (UH) at Manoa School of Ocean and Earth Science and Technology (SOEST).
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In an era of rising sea level, beaches need to migrate landward, otherwise they drown. Beach migration, also known as shoreline retreat, causes coastal erosion of private and public beachfront property. Shoreline hardening, the construction of seawalls or revetments, interrupts natural beach migration -- causing waves to erode the sand, accelerating coastal erosion on neighboring properties, and dooming a beach to drown in place as the ocean continues to rise.The team of scientists, led by graduate researcher in the SOEST Department of Earth Sciences Kammie Tavares, assessed the shoreline around O?ahu that would be most vulnerable to erosion under three scenarios of sea level rise -- all estimated to occur before, and shortly after mid-century.They identified the location and severity of risk of shoreline hardening and beach loss, and a potential timeline for the increase in erosion hazards. The most threatened properties fall into an "administrative erosion hazard zone," an area likely to experience erosion hazards and qualify for the emergency permitting process to harden the shoreline."By assessing computer models of the beach migration caused by 9.8 inches (0.25 meters) of sea level rise, an amount with a high probability of occurring before mid-century, we found that emergency permit applications for shoreline hardening to protect beachfront property will substantially increase," said Tavares.According to co-author Dr. Tiffany Anderson, Assistant Researcher in the Department of Earth Sciences, "We determined that almost 30 percent of all present-day sandy shoreline on O'ahu is already hardened, with another 3.5 percent found to be so threatened that those areas qualify for an emergency permit today. Our modeling indicates that, as sea level rises about 10 inches (0.25 meters) by mid-century, an additional nearly eight percent of sandy shoreline will be at risk of hardening -- meaning at that point, nearly 40% of Oahu's sandy beaches could be lost in favor of hardened shorelines.""In another study published in 2018, we showed that accelerated erosion on neighboring properties, called flanking, usually leads to additional shoreline hardening, and condemnes entire beaches," said co-author Dr. Chip Fletcher, Associate Dean and Professor in SOEST. "It is clear that management decisions made today, and during the careers of most of today's natural resource managers, will be critical in determining if future generations will inherent a healthy shoreline, or one that has been ruined by seawalls, and other types of shoreline hardening."Coastal erosion is inevitable when sea level is rising and global mean sea level has been rising for decades and is accelerating. The Intergovernmental Panel on Climate Change has projected continued sea level rise for many centuries, even if greenhouse gas emissions are reduced or stopped altogether. However, economists are projecting that greenhouse gas emissions will likely continue into mid-century and we will see more years like 2019 when the use of fossil fuels rose faster than the use of renewable forms of energy."Despite these facts, we continue to see shoreline hardening as the preferred policy choice, largely because management agencies have failed to develop assisted transition plans for beachfront landowners who are caught in a tightening vice because of accelerating sea level rise," said Fletcher. "In fact, directly to the contrary, beachfront lands continue to be sold to unwitting buyers with no appreciation for the expensive and frustrating situation they are entering into.""Because coastal zone management laws continue to allow hardship variances in this era of rising sea level, despite widespread knowledge that seawalls kill beaches under these conditions, the same legal system designed to protect public trust lands, is responsible for destroying them," according to Fletcher. "Government agencies must develop creative and socially equitable programs to rescue beachfront owners and free the sandy ecosystem so that it can migrate landward as it must in an era of rising seas. It is urgent that options are developed soon for beachfront landowners and resource managers to avoid further destructive management decisions.""Beaches are critical ecosystems to native plants and animals, offer protection from storms, are an essential cultural setting, and attract tourists, who are important for Hawai'i's current economy," added Tavares. "This research shows that conversations on the future of our beaches and how we will care for them must happen now rather than later, if we are to protect our sandy beaches."
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Climate
| 2,020 |
September 21, 2020
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https://www.sciencedaily.com/releases/2020/09/200921170452.htm
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2020 Arctic sea ice minimum at second lowest on record
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NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder shows that the 2020 minimum extent, which was likely reached on Sept. 15, measured 1.44 million square miles (3.74 million square kilometers).
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In winter, frozen seawater covers almost the entire Arctic Ocean and neighboring seas. This sea ice undergoes seasonal patterns of change -- thinning and shrinking during late spring and summer, and thickening and expanding during fall and winter. The extent of summer sea ice in the Arctic can impact local ecosystems, regional and global weather patterns, and ocean circulation. In the last two decades, the minimum extent of Arctic sea ice in the summer has dropped markedly. The lowest extent on record was set in 2012, and last year's extent was tied for second -- until this year's.A Siberian heat wave in spring 2020 began this year's Arctic sea ice melt season early, and with Arctic temperatures being 14 to 18 degrees Fahrenheit (8 to 10 degrees Celsius) warmer than average, the ice extent kept declining. The 2020 minimum extent was 958,000 square miles (2.48 million square kilometers) below the 1981-2010 average of yearly minimum extents, and 2020 is only the second time on record that the minimum extent has fallen below 1.5 million square miles (4 million square kilometers)."It was just really warm in the Arctic this year, and the melt seasons have been starting earlier and earlier," said Nathan Kurtz, a sea ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The earlier the melt season starts, the more ice you generally lose."Thin ice also melts quicker than thicker floes. Dramatic drops in sea ice extent in 2007 and 2012, along with generally declining summer extent, has led to fewer regions of thick, multi-year ice that has built up over multiple winters. In addition, a recent study showed that warmer water from the Atlantic Ocean, which is typically deep below the colder Arctic waters, is creeping up closer to the bottom of the sea ice and warming it from below.There are cascading effects in the Arctic, said Mark Serreze, director of NSIDC. Warmer ocean temperatures eat away at the thicker multiyear ice, and also result in thinner ice to start the spring melt season. Melt early in the season results in more open water, which absorbs heat from the Sun and increases water temperatures."As the sea ice cover extent declines, what we're seeing is we're continuing to lose that multiyear ice," Serreze said. "The ice is shrinking in the summer, but it's also getting thinner. You're losing extent, and you're losing the thick ice as well. It's a double whammy."The second-lowest extent of sea ice on record is just one of many signs of a warming climate in the north, he said, pointing to the Siberian heat waves, forest fires, hotter-than-average temperatures over the Central Arctic, and the thawing permafrost that led to a Russian fuel spill.
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Climate
| 2,020 |
September 21, 2020
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https://www.sciencedaily.com/releases/2020/09/200921151332.htm
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Climate: Support for simple funding plans -- even if costs are high
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For decades, scientists have urged policymakers to take prompt action to address climate change, but their calls have largely gone unanswered. Now, as wildfires ravage the west and hurricanes batter the Atlantic and Gulf coasts with greater intensity, a new study involving Washington University in St. Louis researchers finds consumers across the United States and in some European countries are ready to start paying for it now.
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One reason why governments have been slow to react is because of the cost-participation dilemma. In order to be effective, a climate policy must raise the price of carbon and include most countries in the world, explained Michael Bechtel, associate professor of political science in Arts & Sciences. But that's a challenge because participation is voluntary, and raising energy costs -- no matter how necessary -- is never popular.As policymakers debate the best way to fund climate action, Bechtel -- along with Kenneth Scheve at Yale University and Elisabeth van Lieshout at Stanford University -- wanted to better understand the public's perspective.In a study published Sept. 21 in Policymakers and pundits have generally assumed that ramping up climate action and costs over time would be the most attractive approach as it would allow consumers to prepare and adjust their energy usage. Instead, they found the majority in all four countries preferred a simpler, constant-cost plan -- even if average household costs are high.Policymakers take note: The constant-cost plan also significantly reduced opposition to climate action, as compared with the ramp-up plan.According to Bechtel, understanding the public's preference for funding climate action is important because these costs would likely be passed on to the consumer."Carbon taxes are meant to change energy-intense production as well as consumption patterns, and they would be paid by businesses and consumers," Bechtel said. "An example is a fuel tax that would directly increase the price of gasoline. A second type of a carbon tax is an emissions tax, which would raise the price of industrial activities that emit greenhouse gases. But even with this type of activity, consumers will ultimately incur higher prices because the increased production costs will require raising the price of such emission-intense goods."Researchers began by introducing the notion of an international agreement, which would entail certain average costs per month and household. Respondents were given the four different options of distributing the costs of implementing the agreement over time and asked to indicate which cost schedule they would select in a referendum given a certain cost level average -- low or high.Across the four countries, 58% of respondents preferred the constant-cost plan, whereas only 12% preferred an increasing-cost plan.Those who favored the constant-cost plan stressed the desire to simplify budgeting and plan for the future. It also encouraged people to reduce their energy usage over time. Even when average household costs were substantial -- adding up to 2% of GDP -- most respondents still preferred the certainty of the constant plan.In comparison, those who preferred the ramp-up approach said this plan allowed people to gradually adjust to rising costs. Respondents also chose this option in the hope that delayed costs would leave less of a consumer impact because of wage increases, inflation, etc.Respondents who preferred higher costs up front emphasized the need to make investments now, which they said were essential to tackling climate change."Credible climate policies will have to raise the price of carbon, and the public are concerned about these costs even when they believe the science of climate change and generally want governments to address the issue," the researchers wrote."As policymakers seek to design policies that are transparent and meet meaningful emission reduction goals, our research indicates that constant-cost plans promise more support for climate action relative to ramping-up approaches."Moreover, due to the delay in large-scale policy responses to climate change, countries will likely have to pursue more progressive and costly climate action to limit the adverse effects of global warming. The drop in support due to higher costs associated with these more ambitious policy efforts may be at least partially mitigated by selecting a set of attractive design features such as the constant distribution of costs."Progress appears challenging, but it is possible. The 2016 Paris Agreement created a global framework to address climate change with countries committing to work together to limit the global average temperature increase to 2°C or less. But it stopped short of prescribing which policy instruments countries could use to reach the collective goal."Countries have agreed that domestic mitigation measures that reduce greenhouse gas emissions are needed," Bechtel said. "This is the goal of carbon pricing: Incentivizing societies to produce less GHG emissions. There are several policy instruments that promise to get us closer to this goal. A carbon tax is one of these instruments, but countries can also use emission trading systems or emission reduction funds, for example. They could also rely on a combination of these policies."
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Climate
| 2,020 |
September 21, 2020
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https://www.sciencedaily.com/releases/2020/09/200921135405.htm
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How to get a handle on carbon dioxide uptake by plants
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How much carbon dioxide, a pivotal greenhouse gas behind global warming, is absorbed by plants on land? It's a deceptively complicated question, so a Rutgers-led group of scientists recommends combining two cutting-edge tools to help answer the crucial climate change-related question.
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"We need to understand how the Earth is breathing now to know how resilient it will be to future change," according to a paper in the journal Global observations suggest that natural ecosystems take up about as much carbon dioxide as they emit. Measuring how much carbon dioxide is absorbed by plants on land is complicated by the carbon exhaled simultaneously by plants and soils, the paper notes.While plants absorb a portion of the increasing emissions of carbon dioxide from fossil fuel burning, scientists have a difficult time determining how much, said lead author Mary Whelan, an assistant professor in the Department of Environmental Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick."By combining two tools that correspond to potential carbon uptake and light captured by leaves, we'll know how much carbon dioxide could remain in the atmosphere," Whelan said. "The two communities of scientists who use these tools need to come together, with the help of funding."The tools focus on two indicators of photosynthesis, when plants harness sunlight to turn carbon dioxide and water into carbohydrates, generating oxygen. One indicator is carbonyl sulfide, a natural trace gas absorbed by plants. The second, called solar-induced fluorescence, is light emitted by leaves during photosynthesis.Combining the two tools will help reveal how much carbon is being absorbed by ecosystems and the consequences for the water cycle. Collecting data via satellites, in the air and on the ground will help improve models to predict changes in the future, according to the paper.
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Climate
| 2,020 |
September 21, 2020
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https://www.sciencedaily.com/releases/2020/09/200921102540.htm
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Corona-induced CO2 emission reductions are not yet detectable in the atmosphere
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Based on current data measured in the energy, industry, and mobility sectors, restrictions of social life during the corona pandemic can be predicted to lead to a reduction of worldwide carbon dioxide emissions by up to eight percent in 2020. According to the Intergovernmental Panel on Climate Change (IPCC), cumulative reductions of about this magnitude would be required every year to reach the goals of the Paris Agreement by 2030. Recent measurements by researchers of Karlsruhe Institute of Technology (KIT) revealed that concentration of carbon dioxide (CO
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The corona pandemic has changed both our working and our private lives. People increasingly work from home, have video conferences instead of business trips, and spend their holidays in their home country. The lower traffic volume also reduces COTo prove this, researchers additionally studied a long-term scenario that can be controlled well with atmospheric measurements: The goal of the Paris Climate Agreement to limit global warming to 1.5 degrees Celsius can only be reached by an immediate significant reduction of COFor the study, the team used data from the Total Carbon Column Observing Network (TCCON). It measured the concentrations in different layers of the atmosphere above Garmisch-Partenkirchen and at other places around the globe. "High-tech infrared spectrometers are applied, which use the sun as a light source. The measurement method is highly precise, uncertainties are in the range of a few thousandths," Sussmann adds.According to the researchers, the long life of COFor their study, the researchers compared the TCCON measurements with the prognoses of the atmospheric growth rate for 2020 - with and without corona restrictions. "Precision analysis of atmosphere measurements revealed that the impacts of COVID-19 measures on the atmosphere might be measured after little more than six months, if the reference state without COVID-19 would be predicted precisely," the climate researcher explains. "In any case, we would be able to find out within presumably two and half years, whether global political and social measures will help us find viable alternatives of fossil fuels and reach the goals of the Paris Climate Agreement."
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Climate
| 2,020 |
September 21, 2020
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https://www.sciencedaily.com/releases/2020/09/200921102555.htm
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Studies investigate marine heatwaves, shifting ocean currents
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North America experienced a series of dangerous heatwaves during the summer of 2020, breaking records from coast to coast. In the ocean, extreme warming conditions are also becoming more frequent and intense. Two new studies from the Woods Hole Oceanographic Institution (WHOI) investigate marine heatwaves and currents at the edge of the continental shelf, which impact regional ocean circulation and marine life.
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In a paper published September 17 in the "This area is a hotspot for increasing temperature and extreme events, with drastic impacts on regional marine species," said lead author Svenja Ryan. "It's important to understand where in the water column temperature and salinity changes are happening so you can determine how the ecosystem will be impacted."For the first time in the Southern Indian Ocean, Ryan and her co-authors, WHOI physical oceanographers Caroline Ummenhofer and Glen Gawarkiewicz, showed that the effects of marine heatwaves extend to 300 meters or more below the surface along the entire west coast of Australia. They found that during La Niña years, the southward-flowing Leeuwin Current becomes stronger and is associated with warm temperature anomalies at greater depths. These conditions were observed during the 2011 marine heatwave that led to the first-recorded coral bleaching at Ningaloo Reef, a World Heritage site, and extensive loss of a nearby kelp forest. During El Niño periods, the temperature and salinity anomalies associated with marine heatwaves are limited to the ocean surface, showing that complex ocean processes play an important role in the depth-extent of extreme events.Ryan and her colleagues are using a similar modeling approach to study marine heatwaves in the Northwest Atlantic. "The challenge, wherever you go, is that marine heatwaves have so many drivers," Ryan said. "Understanding different types of events and their associated depth structure is crucial for regional impact assessment and adaptation strategies, as well as for predicting potential changes in a future climate."While models allow scientists to understand and predict changes to large-scale ocean processes, these models rely on data collected in the field. In a study published Aug. 30, 2020, in the Journal of Geophysical Research: Oceans, lead author Jacob Forsyth made use of 25 years of oceanographic data collected by the container ship (CMV) Oleander on its weekly voyages between New Jersey and Bermuda. These measurements provide valuable insight into the Mid-Atlantic Bight Shelfbreak Jet, a cool-water current that flows south along the continental shelf from Labrador to Cape Hatteras.Forsyth, a graduate student in the MIT-WHOI Joint Program and his co-authors, Gawarkiewicz and WHOI physical oceanographer Magdalena Andres, noticed a distinct relationship between the current and changing sea temperatures. Not only does the Shelfbreak Jet change seasonally -- slowing down considerably from winter to summer -- they also found it had slowed by about 10 percent since data collection began in 1992. The slow-down of the jet is consistent with the long-term warming of the continental shelf."The Shelfbreak Jet is associated with the upwelling of nutrients, which affects the productivity of fisheries," said Gawarkiewicz. "As marine heatwaves become more frequent, we need to understand how that links to the jet."Starting in 2000, researchers began to notice that eddies of warm, salty water breaking off the Gulf Stream -- known as "warm core rings" -- had nearly doubled in number off the New England Continental Shelf. Not only do these rings cause water temperature and salinity to increase, they push the Shelfbreak Jet towards shore, and sometimes entirely shut down or reverse the direction of its flow. The authors noted that shifting currents and temperatures on the continental shelf have already prompted changes in key New England fisheries: cold-loving lobster are slowly moving offshore, while shortfin squid are more commonly found closer to shore."You could call it a 'calamari comeback', where some of these rings are coming onto the continental shelf packed with squid. Others have none," said Gawarkiewicz. "Jacob's work is an important step in unraveling this mystery and helping us predict how currents and shelf temperatures will respond to approaching rings."The oceanographic data collected by the CMV Oleander are essential for understanding rapidly shifting dynamics in a complex system, said the co-authors. Previous studies rely on satellite data, which are limited to measurements of the ocean surface over a wide area. "Looking at the surface might not tell the whole story of what's happening when rings approach the continental shelf, or their effects on upwelling," said Forsyth. "This paper shows how important it is to have this type of long-term monitoring."
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Climate
| 2,020 |
September 18, 2020
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https://www.sciencedaily.com/releases/2020/09/200918154526.htm
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Indian monsoon can be predicted better after volcanic eruptions
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Large volcanic eruptions can help to forecast the monsoon over India -- the seasonal rainfall that is key for the country's agriculture and thus for feeding one billion people. As erratic as they are, volcanic eruptions improve the predictability, an Indian-German research team finds. What seems to be a paradox is in fact due to a stronger coupling between the monsoon over large parts of South and South-East Asia and the El Niño phenomenon after an eruption. Combining data from meteorological observations, climate records, computer model simulations, and geological archives such as tree-rings, corals and ice-cores from past millennia of Earth history, the researchers found that a synchronization of the monsoon with the strongest mode of natural climate variability, the El Niño, makes it easier to anticipate the strength of seasonal rainfall in the Indian subcontinent.
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"The tiny particles and gases that a large volcano blasts into the air enter into the stratosphere and remain there for a few years. While the volcanic matter in the stratosphere to some extent blocks sunshine from reaching the Earth's surface , the reduced solar forcing increases the probability of an El Niño event in the next year," says R. Krishnan from the Indian Institute of Tropical Meteorology in Pune. "This is because less sunshine means less warmth and hence a change of temperature differences between the Northern and Southern hemisphere, which in turn affects the atmospheric large-scale circulation and precipitation dynamics. Advanced data analysis now reveals that large volcanic eruptions are more likely to promote the coincidence of warm El Niño events over the Pacific and Indian monsoon droughts -- or, in contrast, cool La Niña events over the Pacific and Indian monsoon excess.The Indian monsoon strongly depends on the El Niño / Southern Oscillation -- a climatic phenomenon in the tropical Pacific Ocean whose Spanish name means 'the boy', referring to the Christ child because the water near South America is often at its warmest near Christmas. "The synchronization between tropical Pacific Ocean and Indian monsoon is changing over time, with human-made global warming being one of the factors, worsening the accurate prediction of the monsoon," says Norbert Marwan from the Potsdam Institute for Climate Impact Research (PIK). "This in fact confirms a hypothesis that our colleagues Maraun and Kurths launched 15 years ago. The new findings now suggest a novel, additional path for monsoon predictions that are crucial for agricultural planning in India." Previous research from PIK already substantially improved Monsoon prediction for years without volcanic eruptions.The findings can also help further developing climate models and could in fact also help assessing the regional implications of geo-engineering experiments. To reduce global warming from human-made greenhouse gases, some scientists envision solar radiation management -- basically to block a portion of sunrays from warming Earth's surface by putting dust in the high atmosphere, similar to what the natural phenomenon of a volcanic eruption does. Artificially blocking sunshine, however, might dangerously interfere with a number of processes in the atmosphere. Understanding the mechanisms at play is thus important.
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https://www.sciencedaily.com/releases/2020/09/200917180419.htm
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Supercooled water is a stable liquid, scientists show for the first time
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Supercooled water is really two liquids in one. That's the conclusion reached by a research team at the U.S. Department of Energy's Pacific Northwest National Laboratory after making the first-ever measurements of liquid water at temperatures much colder than its typical freezing point.
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The finding, published today in the journal The argument matters because understanding water, which covers 71 percent of the Earth's surface, is critical to understanding how it regulates our environment, our bodies and life itself."We showed that liquid water at extremely cold temperatures is not only relatively stable, it exists in two structural motifs," said Greg Kimmel, a chemical physicist at PNNL. "The findings explain a long-standing controversy over whether or not deeply supercooled water always crystallizes before it can equilibrate. The answer is: no."You'd think we understand water by now. It's one of the most abundant and most studied substances on the planet. But despite its seeming simplicity -- two atoms of hydrogen and one atom of oxygen per molecule -- HIt is surprisingly difficult for water to freeze just below its melting point: water resists freezing unless it has something to get it started, like dust or some other solid to cling to. In pure water, it takes an energetic nudge to jostle the molecules into the special arrangement needed to freeze. And it expands when it freezes, which is weird behavior compared with other liquids. But that weirdness is what sustains life on Earth. If ice cubes sank or water vapor in the atmosphere didn't retain warmth, life on Earth as we know it wouldn't exist.Water's weird behavior has kept chemical physicists Bruce Kay and Greg Kimmel occupied for more than 25 years. Now, they and postdoctoral scientists Loni Kringle and Wyatt Thornley have accomplished a milestone that they hope will expand our understanding of the contortions liquid water molecules can make.Various models have been proposed to explain water's unusual properties. The new data obtained using a sort of stop-motion "snapshot" of supercooled water shows that it can condense into a high-density, liquid-like structure. This higher density form co-exists with a lower-density structure that is more in line with the typical bonding expected for water. The proportion of high-density liquid decreases rapidly as the temperature goes from -18.7 F (245 K) to -117.7 F (190 K), supporting predictions of "mixture" models for supercooled water.Kringle and Thornley used infrared spectroscopy to spy on the water molecules trapped in a kind of stop motion when a thin film of ice got zapped with a laser, creating a supercooled liquid water for a few fleeting nanoseconds."A key observation is that all of the structural changes were reversible and reproducible," said Kringle, who performed many of the experiments.This research may help explain graupel, the fluffy pellets that sometimes fall during cool- weather storms. Graupel forms when a snowflake interacts with supercooled liquid water in the upper atmosphere."Liquid water in the upper atmosphere is deeply cooled," says Kay, a PNNL lab fellow and expert in the physics of water. "When it encounters a snowflake it rapidly freezes and then in the right conditions, falls to Earth. It's really the only time most people will experience the effects of supercooled water."These studies may also help understand how liquid water can exist on very cold planets -- Jupiter, Saturn, Uranus and Neptune -- in our solar system, and beyond. Supercooled water vapor also creates the beautiful tails that trail behind comets.Here on Earth, a better understanding of the contortions water can perform when placed in a tight situation, such as a single water molecule wedged into a protein, could help scientists design new medicines."There isn't a lot of space for the water molecules that surround individual proteins," said Kringle. "This research could shed light on how liquid water behaves in closely packed environments."Thornley noted that "in future studies, we can use this new technique to follow the molecular rearrangements underlying a broad range of chemical reactions."There is still much to be learned, and these measurements will help lead the way to a better understanding of the most abundant life-giving liquid on Earth.
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https://www.sciencedaily.com/releases/2020/09/200917135517.htm
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Curbing land clearing for food production is vital to reverse biodiversity declines
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Preserving terrestrial biodiversity requires more ambitious land-conservation targets to be established and met. At the same time, "bending the curve" on biodiversity loss needs more efficient food production, and healthier and less wasteful consumption and trade. If undertaken with "unprecedented ambition and coordination," these efforts provide an opportunity to reverse terrestrial biodiversity loss by 2050, according to a new study.
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The research was published September 10 in "This important paper adds further evidence that food and environmental security are not incompatible," said Fabrice DeClerck, a co-author and senior scientist at the Alliance of Bioversity International and the International Center for Tropical Agriculture (CIAT), who co-authored 2019's EAT-Lancet report that outlined food system transitions to feed 10 billion people sustainably by 2050.In a novel approach to explore future terrestrial biodiversity trends as affected by habitat conversion, the researchers built an ensemble of models to better understand possible future scenarios, much in the same way the International Panel on Climate Change (IPCC) creates future climate projections. They explore different assumptions -- conservation and restoration efforts, and the impact of more sustainable food production and consumption practices -- to build a timeline for a reversal in biodiversity loss."We wanted to assess in a robust manner whether it might be feasible to bend the curve of declining terrestrial biodiversity due to current and future land use, while avoiding jeopardizing our chances to achieve other Sustainable Development Goals (SDGs)," said David Leclère, the lead author and IIASA researcher. "If this were indeed possible, we also wanted to explore how to get there and, more specifically, what type of actions would be required, and how combining various types of actions might reduce trade-offs among objectives."The study comes at a relevant time for international discussions related to climate, conservation and food systems, including the United Nations Convention on Biological Diversity, which is taking stock of its Strategic Plan for Biodiversity 2011-2020.The research was also featured in the 5th Global Biodiversity Outlook, released this week."We found that apart from increased conservation efforts, the most important actions to revert the loss of biodiversity are all related to how we manage the food system," said Mario Herrero, the chief research scientist for agriculture and food at CSIRO, Australia's national research agency. "Key transitions towards healthy and sustainable diets, renewed waste reduction efforts and increases in productivity will help enormously restore ecosystems. These are central elements where we need investment and action and are an integral part of the forthcoming World Food Summit."Even under a best-case scenario, ongoing land conversion will drive further biodiversity loss before the curve starts bending. At least a third of the projected losses in the coming years are unlikely to be avoided under any scenario. Potential biodiversity losses were found to be highest in the regions richest in biodiversity, including sub-Saharan Africa (SSA), South Asia, Southeast Asia, the Caribbean and Latin America.The study's baseline projections for biodiversity loss -- which include global and local extinctions and reductions in viable population levels for plants and animals -- will be driven by the loss of about 5.3 million km2 of unmanaged forest and natural vegetation by 2050. To have a chance at reversing biodiversity loss -- or bending the biodiversity curve towards restoration -- about 9.8 million km2 must be restored by 2050. This implies a significant increase to the Bonn Challenge, an international agreement to bring 3.5 million km2 into restoration by 2030.While study does not factor in the impact of climate change, the authors discuss climate's increasing role in biodiversity loss, writing:"Land-use change is currently the largest single threat to biodiversity, but other threats will increase in importance in the future, in particular climate change."Additionally, the "Integrated Action Portfolio" proposed by the researchers to address biodiversity loss implies doubling crop yields in SSA, which will be no easy feat. "While significant yield gaps prevailing in this region might offer opportunities, closing the yield gap in a sustainable manner will require investments and innovative policies, and might be complicated by climate change," they wrote."We need to adopt a zero land conversion approach," said DeClerck. "We need to realize that doubling productivity in SSA amongst others is a core contribution to the biodiversity and food security challenge, combined with producing the foods that contribute to, rather than detract from public health."While a rapidly shifting climate is hurting biodiversity, Climate will also play a big role in the sustainable intensification of agriculture, especially in places like sub-Saharan Africa where agricultural production will need to increase considerably in order to meet land conservation goals.Terrestrial habitats will need to be better protected, the researchers argue. Even if current global agreements to protect 17 percent of land by 2020 are more than doubled to 40 percent and include biodiversity hotspots, about half of biodiversity losses projected under the study's baseline scenario will not be avoided.But the effectiveness of protected areas is declining as pressures on those areas are growing.The report is not all bad news. Complementing research published in the past couple of years, the team found that integrated efforts that target habitat conservation, improved production practices and significant shifts towards healthy and less wasteful diets enable reversing the loss of biodiversity. These efforts are similarly necessary to achieve climate security and are not incompatible with global food security targets. Urgent action is needed this decade, however, to have any chance of transitioning to a net-nature positive scenario.
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https://www.sciencedaily.com/releases/2020/09/200917135515.htm
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Wildfire on the rise since 1984 in Northern California's coastal ranges
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High-severity wildfires in northern coastal California have been increasing by about 10 percent per decade since 1984, according to a study from the University of California, Davis, that associates climate trends with wildfire.
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The study, published online in "The severity of wildfires has been increasing over the past four decades," said lead author Yuhan Huang, a graduate student researcher at UC Davis. "We found that fires were much bigger and more severe during dry and hot years compared to other climatic conditions."The study area includes coastal foothills and mountains surrounded by Central Valley lowlands to the east and stretching north to the Klamath Mountains. Berryessa Snow Mountain National Monument resides in the southeast portion. It and several areas described in the study have been impacted by wildfire in recent months during a heat wave and the largest wildfire season recorded in California."Most of the fires occurring now are exacerbated by this heat wave," said co-leading author Yufang Jin, an associate professor in the UC Davis Department of Land, Air and Water Resources. "Our study shows how prolonged and historic dry conditions lead to extreme behaviors of wildfires, especially when they coincide with warmer temperature."The scientists used a machine-learning model that enables near real-time prediction of the likelihood of different levels of fire severity, given ignition. The model shows that during dry years, the northwest and southern parts of the study area are particularly at risk of high-severity fires, although the entire area is susceptible.According to the historical data, about 36 percent of all fires between 1984 and 2017 in the mapped area burned at high severity, with dry years experiencing much higher burn severity. During wet years, however, only about 20 percent of burns were considered high-severity fires, while the remainder burned at moderate or low severity. Higher temperature further amplified the severity of wildfires.The research highlights the importance of careful land-use planning and fuel management in the state's most vulnerable areas to reduce the risk of large, severe fires as the climate becomes drier and warmer."Those are things we can control in the short-term," Jin said. "Prioritizing high-risk areas is something more practical to reduce the damages."
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917122844.htm
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Emissions could add 15 inches to 2100 sea level rise
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An international effort that brought together more than 60 ice, ocean and atmosphere scientists from three dozen international institutions has generated new estimates of how much of an impact Earth's melting ice sheets could have on global sea levels by 2100. If greenhouse gas emissions continue apace, Greenland and Antarctica's ice sheets could together contribute more than 15 inches (38 centimeters) of global sea level rise -- and that's beyond the amount that has already been set in motion by Earth's warming climate.
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The results point to a greater range of possibilities, from ice sheet change that decreases sea level by 3.1 in (7.8 cm), to increasing it by 12 in (30 cm) by 2100, with different climate scenarios and climate model inputs. The regional projections show the greatest loss in West Antarctica, responsible for up to 7.1 in (18 cm) of sea level rise by 2100 in the warmest conditions, according to the research."The Amundsen Sea region in West Antarctica and Wilkes Land in East Antarctica are the two regions most sensitive to warming ocean temperatures and changing currents, and will continue to lose large amounts of ice," said He?le?ne Seroussi, an ice scientist at NASA's Jet Propulsion Laboratory in Southern California. Seroussi led the Antarctic ice sheet modeling in the ISMIP6 effort. "With these new results, we can focus our efforts in the correct direction and know what needs to be worked on to continue improving the projections."Different groups within the ISMIP6 community are working on various aspects of the ice sheet modeling effort. All are designed to better understand why the ice sheets are changing and to improve estimates of how much ice sheets will contribute to sea level rise. Other recent ISMIP6 studies include:"It took over six years of workshops and teleconferences with scientists from around the world working on ice sheet, atmosphere, and ocean modeling to build a community that was able to ultimately improve our sea level rise projections," Nowicki said. "The reason it worked is because the polar community is small, and we're all very keen on getting this problem of future sea level right. We need to know these numbers."The new results will help inform the Sixth IPCC report scheduled for release in 2022.Results from this effort are in line with projections in the Intergovernmental Panel on Climate Change's (IPCC) 2019 Special Report on Oceans and the Cryosphere. Meltwater from ice sheets contribute about a third of the total global sea level rise. The IPCC report projected that Greenland would contribute 3.1 to 10.6 inches (8 to 27 cm) to global sea level rise between 2000-2100 and Antarctica could contribute 1.2 to 11 inches (3 to 28 cm).These new results, published this week in a special issue of the journal The "One of the biggest uncertainties when it comes to how much sea level will rise in the future is how much the ice sheets will contribute," said project leader and ice scientist Sophie Nowicki, now at the University at Buffalo, and formerly at NASA Goddard. "And how much the ice sheets contribute is really dependent on what the climate will do.""The strength of ISMIP6 was to bring together most of the ice sheet modeling groups around the world, and then connect with other communities of ocean and atmospheric modelers as well, to better understand what could happen to the ice sheets," said Heiko Goelzer, a scientist from Utrecht University in the Netherlands, now at NORCE Norwegian Research Centre in Norway. Goelzer led the Greenland ice sheet ISMIP6 effort.With warming air temperatures melting the surface of the ice sheet, and warming ocean temperatures causing ocean-terminating glaciers to retreat, Greenland's ice sheet is a significant contributor to sea level rise. The ISMIP6 team investigated two different scenarios the IPCC has set for future climate to predict sea level rise between 2015 and 2100: one with carbon emissions increasing rapidly and another with lower emissions.In the high emissions scenario, they found that the Greenland ice sheet would lead to an additional global sea level rise of about 3.5 inches (9 cm) by 2100. In the lower emissions scenario, the loss from the ice sheet would raise global sea level by about 1.3 inches (3 cm). This is beyond what is already destined to be lost from the ice sheet due to warming temperatures between pre-industrial times and now; previous studies have estimated that 'locked in' contribution to global sea level rise by 2100 to be about a quarter-inch (6 millimeters) for the Greenland ice sheet.The ISMIP6 team also analyzed the Antarctic ice sheet to understand how much ice melt from future climate change would add to sea level rise, beyond what recent warming temperatures have already put in motion. Ice loss from the Antarctic ice sheet is more difficult to predict: In the west, warm ocean currents erode the bottom of large floating ice shelves, causing loss; while the vast East Antarctic ice sheet can gain mass, as warmer temperatures cause increased snowfall.
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917122842.htm
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Europe's old-growth forests at risk
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Like its ancient cathedrals, Europe has a remarkable -- but poorly understood -- legacy of old-growth forests. These primeval landscapes, scattered on remote hillsides and forested valleys across many countries, are a "living treasure," says University of Vermont scientist Bill Keeton.
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A new study, by scientists from 28 institutions including UVM, presents the first comprehensive assessment of the conservation status of these primary forests in Europe -- and shows that many of them are not protected and at risk of being destroyed.Gathering data and mapping for five years, the team's research makes clear that Europe's ancient forests are in a perilous state -- and that many of them continue to be logged. The researchers conclude that formal conservation of these forests should be a top priority for countries to meet their climate change and biodiversity goals."While many primary forests are in fact well protected, we also found many regions where they are not -- particularly where primary forests are still common," says Francesco Sabatini, the study's lead author from the German Centre for Integrative Biodiversity Research and Martin Luther University, Halle-Wittenberg. "And where they are protected, in some cases, the level of protection is inadequate to ensure these forests will be protected in the long-term."The study also highlights that remaining primary forests are very unevenly distributed across Europe. "Some regions, particularly in Scandinavia and Finland as well as Eastern Europe, still have many primary forests. But often those countries do not realize how unique their forests are at the European scale and how important it is to protect them," says senior author Tobias Kuemmerle from Humboldt University in Berlin. "At the same time, we were shocked to see that there are many natural forests types in Europe without any primary forest remaining at all, particularly in Western Europe."The European Union has recently put forward a new Biodiversity Strategy for 2030 that highlights the value of old-growth forest; the results of this new study provide valuable information for implementing this strategy, the team notes.The new research was published on September 16, 2020, in the journal Earlier research by this same team had shown that many primary forests remain in Europe and modelled where others are likely to occur. "But what we didn't know: are these remaining primary forests representative of the 54 forest types found in Europe? How much of each forest type is protected? And where are opportunities to restore old-growth forest?" says UVM's Bill Keeton, second author on the new study, professor of forest ecology and forestry in the Rubenstein School of Environment and Natural Resources, and fellow in the Gund Institute for Environment. "This research answers these critical questions."Primary forests are forests without signs of past human use and where ecological processes are not disrupted by human influence. "Primary and old-growth forests have huge value for biodiversity, for carbon and climate mitigation, for flood resilience and other ecological values -- and they're important as part of Europe's historical legacy just like their ancient cities and cathedrals," says Keeton. In Europe, where millennia of land use have transformed forested landscapes, very few such forests remain, and these are mostly found in remote and relatively unproductive areas.The new study found a "substantial bias," the scientists write, in how these remaining primary forests are distributed across forest types. Of the 54 forest types they assessed, they found that six had no remaining old-growth stands at all. And in two-thirds of the forest types, they found that less than one percent was old growth. And only ten forest types had more than half of their old growth strictly protected.In other words, even if scarce and irreplaceable, many of these primary forests are not legally protected and continue to be logged in Europe. However, with swift action, strict conservation protections on those that remain can be put in place, the team says -- plus: old-growth forests, and their many values, can be restored."Notre Dame burned, but it's being restored," says UVM's Keeton. "It won't be exactly the same as the original construction -- and there's debate over architectural details and what style to use for its spire -- but it will return as an inspiring, ancient place for reflection and worship. The active restoration of old-growth forests is similar. We're not going to create exactly what was there before, but many functions, like habitat and carbon storage, can return." The new study identifies many of the most promising areas for this kind of work."Forest restoration to establish primary forests will take a long time, but it is attractive because such forests will not only benefit biodiversity but also store a lot of carbon and therefore help to mitigate climate change," says Tobias Kuemmerle. "The good news is that there are huge opportunities for restoring primary forests even within existing protected areas, which means that restoration efforts would not necessarily require reducing the area of forests used for timber production.""Now is the time to be ambitious. There is a lot of momentum for forest conservation and restoration in Europe at the moment," says Francesco Sabatini, in part because of the European Union's Biodiversity Strategy for 2030 that explicitly recognizes the irreplaceable value of primary forests. "Our study provides a foundation for putting this strategy into practice," he says."Our work shows that all the remaining primary forests in Europe could be protected with a modest expansion of protected areas," says UVM's Bill Keeton, "and I think this study will change the whole dialogue around old forest restoration in Europe, highlighting where that would be most valuable."
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917105358.htm
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Saharan dust reaching Amazon quantified
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A new study by researchers at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science and ATMO Guyane quantified the amount of Saharan dust reaching the Amazon to better understand how dust could impact soil fertility in the region. Intense tropical weathering and local biomass burning have both contributed to nutrient-poor soil in the Amazon Basin.
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The research team analyzed 15 years of daily measurements of African dust transported in trade winds and collected at a coastal research station in Cayenne, French Guiana. The results showed that significant quantities of dust reach the heart of the Amazon Basin and are deposited there."African dust provides an important source of nutrients to enhance Amazonian soil fertility," said Joseph Prospero, professor emeritus at the UM Rosenstiel School and lead author of the study.Every year, mineral-rich dust from North Africa's Sahara Desert is lifted into the atmosphere by winds and carried on a 5,000-mile journey across the North Atlantic to the Americas. African dust contains phosphorus and other important plant nutrients that help offset soil losses and increase Amazonian soil fertility.This study, the first to quantify African dust transport to South America, showed that significant amounts of dust is deposited to the Amazon. The analysis also found that previous studies, which were based on limited measurements of dust, may have greatly overestimated the impact.The Amazon Basin plays a major role in global climate. Trees and plants in the Amazon remove huge quantities of carbon dioxide from the atmosphere and store the carbon in vegetation. This removal offsets some of the human-made COThe scientists also found that quantities of dust transported to South America are inversely linked to rainfall in North Africa and concluded that climate change will affect dust transport to South America."Changes in dust transport could affect plant growth in the Amazon and the amount of CO
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917105354.htm
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Sea ice triggered the Little Ice Age
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A new study finds a trigger for the Little Ice Age that cooled Europe from the 1300s through mid-1800s, and supports surprising model results suggesting that under the right conditions sudden climate changes can occur spontaneously, without external forcing.
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The study, published in While previous experiments using numerical climate models showed that increased sea ice was necessary to explain long-lasting climate anomalies like the Little Ice Age, physical evidence was missing. This study digs into the geological record for confirmation of model results.Researchers pulled together records from marine sediment cores drilled from the ocean floor from the Arctic Ocean to the North Atlantic to get a detailed look at sea ice throughout the region over the last 1400 years."We decided to put together different strands of evidence to try to reconstruct spatially and temporally what the sea ice was during the past one and a half thousand years, and then just see what we found," said Martin Miles, an INSTAAR researcher who also holds an appointment with NORCE Norwegian Research Centre and Bjerknes Centre for Climate Research in Norway.The cores included compounds produced by algae that live in sea ice, the shells of single-celled organisms that live in different water temperatures, and debris that sea ice picks up and transports over long distances. The cores were detailed enough to detect abrupt (decadal scale) changes in sea ice and ocean conditions over time.The records indicate an abrupt increase in Arctic sea ice exported to the North Atlantic starting around 1300, peaking in midcentury, and ending abruptly in the late 1300s."I've always been fascinated by not just looking at sea ice as a passive indicator of climate change, but how it interacts with or could actually lead to changes in the climate system on long timescales," said Miles. "And the perfect example of that could be the Little Ice Age.""This specific investigation was inspired by an INSTAAR colleague, Giff Miller, as well as by some of the paleoclimate reconstructions of my INSTAAR colleagues Anne Jennings, John Andrews, and Astrid Ogilvie," added Miles. Miller authored the first paper to suggest that sea ice played an essential role in sustaining the Little Ice Age.Scientists have argued about the causes of the Little Ice Age for decades, with many suggesting that explosive volcanic eruptions must be essential for initiating the cooling period and allowing it to persist over centuries. One the hand, the new reconstruction provides robust evidence of a massive sea-ice anomaly that could have been triggered by increased explosive volcanism. One the other hand, the same evidence supports an intriguing alternate explanation.Climate models called "control models" are run to understand how the climate system works through time without being influenced by outside forces like volcanic activity or greenhouse gas emissions. A set of recent control model experiments included results that portrayed sudden cold events that lasted several decades. The model results seemed too extreme to be realistic -- so-called Ugly Duckling simulations -- and researchers were concerned that they were showing problems with the models.Miles' study found that there may be nothing wrong with those models at all."We actually find that number one, we do have physical, geological evidence that these several decade-long cold sea ice excursions in the same region can, in fact do, occur," he said. In the case of the Little Ice Age, "what we reconstructed in space and time was strikingly similar to the development in an Ugly Duckling model simulation, in which a spontaneous cold event lasted about a century. It involved unusual winds, sea ice export, and a lot more ice east of Greenland, just as we found in here." The provocative results show that external forcing from volcanoes or other causes may not be necessary for large swings in climate to occur. Miles continued, "These results strongly suggest...that these things can occur out of the blue due to internal variability in the climate system."The marine cores also show a sustained, far-flung pulse of sea ice near the Norse colonies on Greenland coincident with their disappearance in the 15th century. A debate has raged over why the colonies vanished, usually agreeing only that a cooling climate pushed hard on their resilience. Miles and his colleagues would like to factor in the oceanic changes nearby: very large amounts of sea ice and cold polar waters, year after year for nearly a century."This massive belt of ice that comes streaming out of the Arctic -- in the past and even today -- goes all the way around Cape Farewell to around where these colonies were," Miles said. He would like to look more closely into oceanic conditions along with researchers who study the social sciences in relation to climate.
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917105348.htm
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0.5°C of additional warming has a huge effect on global aridity
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In a new climate modeling study, researchers from the Institute of Industrial Science, The University of Tokyo have revealed major implications for global drought and aridity when limiting warming to 1.5°C rather than 2°C above pre-industrial levels. Drought has serious negative impacts on both human society and the natural world and is generally projected to increase under global climate change. As a result, assessment of the risk of drought under climate change is a critical area of climate research.
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In the 2015 Paris Agreements, the United Nations Framework Convention on Climate Change (UNFCCC) proposed that the increase in global average temperature should be limited to between 1.5°C and 2°C above pre-industrial levels to limit the effects of severe climate change. However, there have been few studies focusing on the relative importance of this 0.5°C of global average temperature rise and what effect it might have on drought and aridity around the world."We wanted to contribute to the understanding of how important that 0.5°C could be, but it such a study is not easy to conduct based on previous modeling approaches," explains corresponding author Hyungjun Kim. "This is mainly because most models look at the extreme high levels and you cannot simply take a slice out of the data while the model spins up to this maximum. Therefore, we used data from the specially designed Half a degree Additional warming Prognosis and Projected Impacts (HAPPI) project to assess the impacts on aridity based on estimations of the balance between water and energy at the Earth's surface."The study revealed that 2°C of warming led to more frequent dry years and more severe aridification in most areas of the world compared with 1.5°C, which emphasizes that efforts should be made to limit warming to 1.5°C above pre-industrial levels."There is a really strong message that some parts of the world could have more frequent drought at 2°C than at 1.5°C. This situation could be especially severe in the Mediterranean, western Europe, northern South America, the Sahel region, and southern Africa," says lead author Akira Takeshima. "However, this situation is highly regional. In some parts of the world, like Australia and some of Asia, the opposite situation was simulated, with a wetter climate at 2°C than at 1.5°C."These findings show the importance of considering the regional impacts of the additional 0.5°C of warming, especially with respect to any future relaxation of the 1.5°C target.
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https://www.sciencedaily.com/releases/2020/09/200917105339.htm
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New estimates for the rise in sea levels due to ice sheet mass loss under climate change
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An international consortium of researchers under the aegis of CMIP6 has calculated new estimates for the melting of Earth's ice sheets due to greenhouse gas emissions and its impact on sea levels, showing that the ice sheets could together contribute more than 40 cm by the end of 2100.
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One of the many effects of global warming is the increase of sea levels due to the melting and retreat of the ice sheets in the Arctic and the Antarctic. As the sea level rises, large areas of densely populated coastal land will become uninhabitable. It is vital that we understand the impact climate change interventions could have on the rate of melting and, consequently, changes in sea level.The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), consisting of more than 60 scientists from 36 institutions across the world -- including Dr. Christopher Chambers and Professor Ralf Greve from the Institute of Low Temperature Science at Hokkaido University -- has used the latest generation of models to estimate the impact of global warming on ice sheets. Their results were published in a special issue of the journal The The ISMIP6 team projected the changes of the Greenland and Antarctic Ice Sheets (GrIS/AIS) between 2015 and 2100 under global warming conditions predicted by climate modelling. The advantage of ISMIP6 was that it used fourteen different models to estimate the changes in the ice sheet under two greenhouse gas (GHG) emissions pathways: the pessimistic scenario, where there is no change in current trends, leading to a rapid increase in GHG emissions; and the optimistic scenario, where comprehensive steps are taken to reduce GHG emissions. Using different models to estimate the changes was vital to this endeavour, as they have different baselines and assumptions.Ralf Greve and Christopher Chambers modelled the behavior of ice sheets using the SICOPOLIS model. The first version was released in 1995 by Greve, and since then it has been continuously developed and used for a large number of studies. The SICOPOLIS model uses data from 1990 as a baseline for the experiments. As the model has a 25-year history with an uninterrupted development and publication record, it brought a unique perspective to ISMIP6.The rate of ice sheet change was modelled under different forcings provided by climate models: future changes of precipitation, surface melting over the ice sheets, surface and ocean temperatures. The goal was to estimate how much the mass loss of the ice sheets would contribute to the rise in average sea levels beyond what has already been put in motion. The study found that, by 2100, the GrIS would raise sea levels by 4-14 cm under the pessimistic scenario, but only 1.5-5 cm under the optimistic scenario. For the AIS, the results point to a greater range of possibilities, from ice sheet change that decreases sea level by 7.8 cm to increasing it by 30 cm under the pessimistic scenario, and an increase of 0-3 cm under the optimistic scenario."Mass change from the AIS is notoriously difficult to predict: Increasing ocean temperatures erode the bottom of large floating ice shelves, causing loss; while the AIS can also gain mass by increased snowfall due to warmer air temperatures. However, we are constantly improving our understanding of the ice sheets and their interaction with the Earth's climate system. Modelling intercomparison studies like ISMIP6 are an effective tool to provide society with the necessary information, including uncertainties, for rational decisions," said Ralf Greve.This effort took over six years of collaboration, and the findings of ISMIP6 will help inform the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC), scheduled for release in 2022. ISMIP6 is part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). CMIP6 currently has a total of 23 endorsed Model Intercomparison Projects (MIPs), and has been invaluable in assessing our understanding of climate and climate change.
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Climate
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917105321.htm
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Ocean acidification puts deep-sea coral reefs at risk of collapse
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Deep-sea coral reefs face challenges as changes to ocean chemistry triggered by climate change may cause their foundations to become brittle, a study suggests.
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The underlying structures of the reefs -- which are home to a multitude of aquatic life -- could fracture as a result of increasing ocean acidity caused by rising levels of carbon dioxide.Hundreds of metres below the surface of the ocean in Southern California, researchers measured the lowest -- therefore the most acidic -- pH level ever recorded on living coral reefs. The corals were then raised in the lab for one year under the same conditions.Scientists observed that the skeletons of dead corals, which support and hold up living corals, had become porous due to ocean acidification and rapidly become too fragile to bear the weight of the reef above them.Previous research has shown that ocean acidification can impact coral growth, but the new study demonstrates that porosity in corals -- known as coralporosis -- leads to weakening of their structure at critical locations.This causes early breakage and crumbling, experts say, that may cause whole coral ecosystems to shrink dramatically in the future, leaving them only able to support a small fraction of the marine life they are home to today.The findings complement recent evidence of porosity in tropical corals, but demonstrate that the threat posed by ocean acidification is far greater for deep-sea coral reefs.Research was led by University of Edinburgh scientists, under the EU-funded ATLAS and iAtlantic projects, with researchers from Heriot-Watt University and the National Oceanic and Atmospheric Administration (NOAA).The team identified how reefs could become fractured by analysing corals from the longest-running laboratory studies to date, and by diving with submersibles off US Pacific shores to observe how coral habitat is lost as the water becomes more acidic.Dr Sebastian Hennige, of the University of Edinburgh's School of GeoSciences, said: "This study highlights that a major threat to these wonderful deep-sea ecosystems is structural weakening caused by ocean acidification, driven by the increasing amounts of carbon dioxide we produce. While deep-sea reefs exist out of sight they are certainly not out of mind, and our work highlights how scientists from different disciplines and countries can join together to tackle global challenges."The corals in Southern California -- one the most acidified reefs studied to date -- are already experiencing the effects of climate change and exist in conditions that most deep-sea reefs are expected to encounter by the end of the century, scientists say.Dr. Peter Etnoyer, of NOAA's National Centers for Coastal Ocean Science, said: "Deep-sea corals growing off Southern California are a window into the future ocean. The region is a natural laboratory to study the effects of ocean acidification."Submersibles were launched from NOAA ships off Southern California, and were guided by Dr. Peter Etnoyer and graduate student Leslie Wickes.The US team sampled live corals and returned them to the laboratory for experiments. The UK team applied engineering principles to demonstrate the rapid weakening of the skeletons and discovered a striking similarity to the weakening observed in human bones from osteoporosis.The team says that the link between osteoporosis and coralporosis opens up a range of methods and concepts that can be adapted in the challenge of monitoring and predicting the fate of such fragile deep-sea ecosystems and the life they support.Dr. Uwe Wolfram, of Heriot-Watt University, said: "By being able to adapt strategies to coral reefs that are used routinely to monitor osteoporosis and assess bone fracture risk, we may have powerful non-invasive tools at our disposal to monitor these fragile ecosystems."Tools developed as part of the project will aid understanding of when ocean ecosystems will change and how it will affect marine life.This will better equip society to deal with how these vulnerable ecosystems can be protected in the future, and will support the UN Decade of Ocean Science -- which starts in 2021 -- to deliver the science we need, for the ocean we want, the team says.Professor J Murray Roberts, of the University of Edinburgh's School of GeoSciences, who leads the ATLAS and iAtlantic programmes, said: "Cold-water corals are truly the cities of the deep-sea providing homes to countless other animals. If we lose the corals the city crumbles. This project is a great example of how we can work across the Atlantic and Pacific Oceans to understand the impacts of rapidly changing ocean conditions."The research is published in the journal
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Climate
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917105400.htm
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Climate change threatens Komodo dragons
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The world's largest lizard, the Komodo dragon, could be driven to extinction by climate change unless significant measures to intervene are taken soon.
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A new international study, led by the University of Adelaide and Deakin University, has found that the impact of both global warming and sea-level rise threatens the extinction of Komodo dragons, which already have restricted habitats, and this must be better incorporated into conservation strategies."Climate change is likely to cause a sharp decline in the availability of habitat for Komodo dragons, severely reducing their abundance in a matter of decades," says lead author Dr Alice Jones from the University of Adelaide's School of Biological Sciences. "Our models predict local extinction on three of the five island habitats where Komodo dragons are found today."The Komodo dragon, Varanus komodoensis, is the world's most iconic lizard species which has existed on Earth for more than a million years, but only an estimated 4000 individuals survive in the wild. They are endemic to five islands in southeast Indonesia: Komodo, Rinca, Nusa Kode and Gili Motang which are part of Komodo National Park, and Flores, the fifth and largest island which has three nature reserves."Current-day conservation strategies are not enough to avoid species decline in the face of climate change. This is because climate change will compound the negative effects of already small, isolated populations," says Dr Jones."Interventions such as establishing new reserves in areas that are predicted to sustain high-quality habitats in the future, despite global warming, could work to lessen the effects of climate change on Komodo dragons.This study, which is published in the journal "Using this data and knowledge in conservation models has provided a rare opportunity to understand climate change impacts on Indonesia's exceptional but highly vulnerable biodiversity," says co-author Dr Tim Jessop, School of Life and Environmental Sciences, Deakin University.Importantly, the research project involved close collaboration with the Komodo National Park and the Eastern Lesser Sunda Cen¬tral Bureau for Conservation of Natural Resources."The severity and extent of human actions impacting Komodo dragon populations, especially on Flores Island, are only just being realised," says co-author Deni Purwandana, Coordinator of the Komodo Survival Program."Having an insight into future impacts of climate change provides new possibilities to work with conservation agencies and local communities to find on-ground solutions that will limit climate and other threats to Komodo dragons and their habitats."The researchers say climate-change-informed decisions should be a common part of conservation practice."Our conservation models show that Komodo dragons on two protected large islands are less vulnerable to climate change. However, even these island habitats might not provide an adequate insurance policy for the survival of the species," says Associate Professor Damien Fordham from the University of Adelaide's Environment Institute."Conservation managers in coming decades may need to consider translocating animals to sites where Komodo dragons have not been found for many decades. This scenario can be tested easily using our approach."Our research shows that without taking immediate action to mitigate climatic change, we risk committing many range restricted species like Komodo dragons to extinction."
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Climate
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September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917084058.htm
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Effective pathway to convert CO2 into ethylene
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A research team from Caltech and the UCLA Samueli School of Engineering has demonstrated a promising way to efficiently convert carbon dioxide into ethylene -- an important chemical used to produce plastics, solvents, cosmetics and other important products globally.
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The scientists developed nanoscale copper wires with specially shaped surfaces to catalyze a chemical reaction that reduces greenhouse gas emissions while generating ethylene -- a valuable chemical simultaneously. Computational studies of the reaction show the shaped catalyst favors the production of ethylene over hydrogen or methane. A study detailing the advance was published in "We are at the brink of fossil fuel exhaustion, coupled with global climate change challenges," said Yu Huang, the study's co-corresponding author, and professor of materials science and engineering at UCLA. "Developing materials that can efficiently turn greenhouse gases into value-added fuels and chemical feedstocks is a critical step to mitigate global warming while turning away from extracting increasingly limited fossil fuels. This integrated experiment and theoretical analysis presents a sustainable path towards carbon dioxide upcycling and utilization."Currently, ethylene has a global annual production of 158 million tons. Much of that is turned into polyethylene, which is used in plastic packaging. Ethylene is processed from hydrocarbons, such as natural gas."The idea of using copper to catalyze this reaction has been around for a long time, but the key is to accelerate the rate so it is fast enough for industrial production," said William A. Goddard III, the study's co-corresponding author and Caltech's Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics. "This study shows a solid path towards that mark, with the potential to transform ethylene production into a greener industry using COUsing copper to kick start the carbon dioxide (COTo overcome these two hurdles, the researchers focused on the design of the copper nanowires with highly active "steps" -- similar to a set of stairs arranged at atomic scale. One intriguing finding of this collaborative study is that this step pattern across the nanowires' surfaces remained stable under the reaction conditions, contrary to general belief that these high energy features would smooth out. This is the key to both the system's durability and selectivity in producing ethylene, instead of other end products.The team demonstrated a carbon dioxide-to-ethylene conversion rate of greater than 70%, much more efficient than previous designs, which yielded at least 10% less under the same conditions. The new system ran for 200 hours, with little change in conversion efficiency, a major advance for copper-based catalysts. In addition, the comprehensive understanding of the structure-function relation illustrated a new perspective to design highly active and durable COHuang and Goddard have been frequent collaborators for many years, with Goddard's research group focusing on the theoretical reasons that underpin chemical reactions, while Huang's group has created new materials and conducted experiments. The lead author on the paper is Chungseok Choi, a graduate student in materials science and engineering at UCLA Samueli and a member of Huang's laboratory.
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Climate
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September 16, 2020
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https://www.sciencedaily.com/releases/2020/09/200916154854.htm
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Turbulence affects aerosols and cloud formation
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Chat with an atmospheric scientist for more than a few minutes, and it's likely they'll start advocating for a planetary name change. Planet Ocean-Cloud is much more fitting than Earth, they'll say, when so much of our planet's life systems are affected by the interactions of clouds and the oceans.
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The ability to predict the behavior of clouds gives meteorologists, climate scientists, physicists and others a better understanding of change of precipitation (currently one of the most difficult aspects of weather forecasting to predict) and improves climate modeling.Last week, Prasanth Prabhakaran, Will Cantrell and Raymond Shaw, along with several coauthors, published "The role of turbulent fluctuations in aerosol activation and cloud formation" in the journal "There are very few absolutes in life and I'm about to give you one of them: When you look up in the sky, every cloud droplet you see formed on a preexisting speck of dust. But not every speck of dust will give you a cloud droplet," said Will Cantrell, professor of physics."If you give me the atmospheric conditions, I can give you a pretty good idea of whether the speck of dust will form a cloud droplet. So far in atmospheric science, what we haven't accounted for is the fact that the atmosphere is turbulent," Cantrell said. "If the dust particles were identical, but they are exposed to different conditions, that will play a role in whether they become cloud droplets."The role of turbulence in cloud formation is the gap Cantrell's research steps into. Traditionally, the mechanics of cloud formation have not accounted for turbulence. Prabhakaran and coauthors have developed a framework, backed with experiments from Tech's cloud chamber, to explain how preexisting aerosol (dust) particles -- the seeds of cloud droplets -- make the transition to becoming droplets (and thus become eligible to start the process of falling on your garden).Michigan Tech's cloud chamber is one of only two in the world capable of performing such experiments. Shaw, distinguished professor of physics and director of Michigan Tech's atmospheric sciences PhD program, is also affiliated with the other: the LACIS-T chamber in Leipzig, Germany, at the Institute for Tropospheric Research. Clouds can be maintained for hours in Michigan Tech's chamber, a huge advantage over in situ experiments in a jet outfitted with measurement equipment traveling a hundred meters a second through a cloud."Under controlled conditions we investigated the aspects of cloud formation," said Prabhakaran, who is a postdoctoral research scholar in Michigan Tech's department of physics. "Modeling under different regimes shows how cloud droplets form and the significance of formation of cloud droplets under the conditions we have, whether it's a highly polluted environment or out in a relatively clean environment like out over the ocean."Atmospheric conditions matter: In clean conditions, all researchers need to know are the mean values such as average water vapor concentration and average temperature, to have enough information to predict whether dust specks will become cloud droplets. Under more polluted conditions, the exact conditions the particles are exposed to becomes more important."The way that clouds interact with sunlight and whether they precipitate will depend a lot on how many droplets and how big they are," Cantrell said. "Understanding the transition from dust to cloud droplets is a key part of understanding whether you'll have a lot or few droplets. Our theory adds a way to understand whether the turbulent mixing in the atmosphere will affect the number of droplets you get, and that cascades into other properties of cloud formation."To conduct the experiment, the researchers created a turbulent environment inside the 3.14 meters cubed cloud chamber by heating the chamber's lower plate and cooling the top plate to create a turbulent, convective flow. Into the flow the team introduced 130-nanometer sodium chloride aerosol particles. By varying the temperature differential between the top and bottom plates and the number of aerosol particles in the chamber, the researchers saw differences in how clouds formed.Based on those observations, the research team developed a semiquantitative theory to describe the conditions. Whether aerosol particles become droplets has a tremendous effect on the properties of clouds, and the Michigan Tech experiments and model provide a framework to categorize droplet formation in numerical models.Cantrell said turbulence has not been a part of the cloud physics curriculum until very recently."Our measurements in the chamber show that turbulence can mimic the behaviors that have been attributed to particle variation, primarily size and composition. This experiment changes our understanding of the properties of the clouds and we become better able to represent those processes in climate models," he said.The researchers said their model will help forecasters predict the fluctuations Planet Ocean-Cloud will experience as the climate changes."Hopefully within a few years, this will improve the observations of climate models for predicting long-term climate change," Prabhakaran said.
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Climate
| 2,020 |
September 16, 2020
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https://www.sciencedaily.com/releases/2020/09/200916130845.htm
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Colorado's famous aspens expected to decline due to climate change
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Along three scenic drives through Colorado's Rocky Mountains in fall, tourists will see less of a brilliant golden tree in the next 100 years, researchers from North Carolina State University projected in a new study.
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Using computer modeling, researchers simulated how the distribution of quaking aspen, or Populus tremuloides, a native tree known for its brilliant yellow and orange foliage in fall and the sound of its trembling leaves, will change amid rising temperatures over the next 100 years.They predicted quaking aspens will decline in visibility in 2120 under climate warming scenarios. Visibility will also decline along three scenic national byways in the Colorado Rockies -- even if climate conditions remain at historical levels. They saw the greatest declines in the visible landscape areas."Aspen are sensitive to drought and warming temperatures, and empirically we are already starting to see declines," said the study's senior author Jelena Vukomanovic, assistant professor in the NC State Department of Parks, Recreation and Tourism Management. "Even if we keep current conditions, we will see declines in aspen. But under worsening climate change, the decline in aspen will be worse."In the study, researchers modeled the distribution of quaking aspen trees visible under three scenarios: If climate does not change from historical conditions observed from 1980 to 2010; under a 4-degree temperature increase with 15 percent less precipitation; and with a 4-degree decline and 15 percent more precipitation.For each scenario, their simulation modeled whether aspens were visible from 32,949 different vantage points along three scenic roadways in Colorado: Cache la Poudre, Trail Ridge Road and Peak-to-Peak Highway. They used a computer model of forest dynamics called the Landscape Disturbance and Succession (LANDIS-II) model to forecast where aspen will grow and used U.S. Geological Survey elevation data to model visibility along scenic roads.In addition to factoring in changes in temperature and precipitation, they also modeled how wildfires, insects and wind events would impact aspen tree growth and distribution. These trees are intolerant of drought and shade, researchers said, but they are often the first to colonize a burned area.Overall, they found that aspen are expected to decline in all three climate scenarios. In the two warmer scenarios, the losses were more than two times greater overall, and aspen loss was even greater in the visible areas from the scenic byways."We can say with good confidence that these main arteries of movement through the mountains will see a noticeable decline in visible aspen, and the loss of visible aspen is greater than the overall loss," said Vukomanovic. "It's hard to predict what people will do -- build new roads, new outlooks, or create new opportunities to view the remaining stands -- but there could be a negative impact to some of the communities along these routes that rely on tourism dollars from aspen viewing."They saw that the changes in aspen varied depending on the elevation. Aspen at the lowest elevations, where they are the least abundant, saw increases under all three scenarios, but the increases were smaller with climate change. Researchers hypothesized that at these elevations, the model was capturing aspen regeneration after wildfire, but they regenerate to a lesser degree under the more extreme climate change scenarios."We think they are increasing at lower elevations because they're colonizing recently burned places," Vukomanovic said. "Because there's been such active fire suppression at the lower elevations where people live, when fire comes, it creates opportunities for the aspen to colonize new places. But these gains are tiny compared to losses at higher elevations."At the middle elevations of 2,000 to 3,000 meters, where aspen are most abundant, they saw consistent decreases across all three scenarios. At the highest elevations above 3,000 meters, they saw lower declines under the climate warming scenarios. They believe this means aspen distributions will shift to higher elevations as the climate warms."As drought and higher temperatures at lower elevations start to increase the vulnerability of aspens to pathogens like bugs, fungi and bacteria, their suitable climate will shift upwards," said Nikki C. Inglis, a research assistant and graduate student in the Center for Geospatial Analytics at NC State and first author of the study.Researchers said their study is important because it is evidence for how climate change will be visible to people. In addition, the aspen trees in particular are an important feature of the Colorado landscape."They are part of how people who live in Colorado identify themselves, and what makes this a unique landscape," Inglis said. "They draw people in from all over because the aspen trees create a sensory experience with sound and sight. And of course the color change is absolutely striking -- there's nothing like it."
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Climate
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September 16, 2020
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https://www.sciencedaily.com/releases/2020/09/200916113536.htm
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Marine animals live where ocean is most breathable, ranges may shrink with climate change
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As oceans warm due to climate change, scientists are trying to predict how marine animals -- from backboned fish to spineless jellyfish -- will react. Laboratory experiments indicate that many could theoretically tolerate temperatures far higher than what they encounter today. But these studies don't mean that marine animals can maintain their current ranges in warmer oceans, according to Curtis Deutsch, an associate professor of oceanography at the University of Washington.
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"Temperature alone does not explain where in the ocean an animal can live," said Deutsch. "You must consider oxygen: how much is present in the water, how well an organism can take up and utilize it, and how temperature affects these processes."Species-specific characteristics, overall oxygen levels and water temperature combine to determine which parts of the ocean are "breathable" for different ocean-dwelling creatures. New research led by Deutsch shows that a wide variety of marine animals -- from vertebrates to crustaceans to mollusks -- already inhabit the maximum range of breathable ocean that their physiology will allow.The findings, published Sept. 16 in "Organisms today are basically living right up to the warmest temperatures possible that will supply them with adequate oxygen for their activity level -- so higher temperatures are going to immediately affect their ability to get enough oxygen," said Deutsch. "In response to warming, their activity level is going to be restricted or their habitat is going to start shrinking. It's not like they're going to be fine and just carry on."Oxygen levels and temperatures vary throughout ocean waters. Generally, water near the equator is warmer and contains less oxygen than the cooler waters near the poles. But moving from the surface ocean to deeper waters, both oxygen and temperature decrease together. These principles create complex 3-D patterns of oxygen and temperature levels across depths and latitudes. An organism's anatomy, physiology and activity level determine its oxygen needs, how effectively it takes up and uses the available oxygen in its environment, and how temperature affects its oxygen demand.Deutsch and his co-authors -- Justin Penn, a UW doctoral student in oceanography, and Brad Seibel, a professor at the University of South Florida -- wanted to understand if breathability was a limiting factor in determining the ranges of marine animals today. They combined data on temperature and oxygen content across the oceans with published studies of the physiology, oxygen demand and metabolism of 72 species from five different groups of marine animals: cold-blooded vertebrates, like fish, and their relatives; crustaceans; mollusks; segmented worms; and jellyfish and their relatives.The team modeled which parts of the ocean are and aren't habitable for each species. Researchers show that a species' current range generally overlapped with the parts of the oceans predicted to be habitable for it. Their model predicts that the northern shrimp, a crustacean, should be able to get enough oxygen in cool waters north of about 50 degrees north latitude -- and that is generally the shrimp's range today. The small-spotted catshark can inhabit temperate and cool waters at a variety of depths, but near the tropics only near-surface waters -- above about 300 feet -- are breathable, which is also reflected in its current range.In many cases, species ranges are right up to the edge of breathability, which indicates that for marine animals the ability to get enough oxygen may be a major limiting factor in determining where they can live, Deutsch added. Outside of that range, organisms run the risk of hypoxia, or not getting enough oxygen.Temperature affects both how much oxygen that seawater can hold, and how much oxygen an animal needs to maintain the same level of activity. The already-tight overlap the researchers saw between breathability and current ranges indicate that long-term rises in temperature, as expected under climate change, will likely restrict the ranges of many marine animals.This new study follows a 2015 study of four Atlantic Ocean species by Deutsch's team, and builds on its findings by showing that diverse species in all ocean basins are generally inhabiting the maximum range they currently can.In the future, Deutsch wants to include additional species, and further explore the relationships among temperature, oxygen and physiology.The researchers would also like to find historical examples of marine species shifting their range in response to water breathability, as the team showed earlier this year with the northern anchovy."What we really want to find are more observations of marine species moving around in accordance with what we'd expect with temperature conditions and oxygen availability," said Deutsch. "That will give us firm examples of what to expect as temperature and oxygen conditions fluctuate, and shift permanently with climate change."The research was funded by the Gordon and Betty Moore Foundation, the National Oceanic and Atmospheric Administration and the National Science Foundation.Grant numbers: GBMF#3775, OCE-1419323, OCE-1458967
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Climate
| 2,020 |
September 16, 2020
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https://www.sciencedaily.com/releases/2020/09/200916113452.htm
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Siberia's permafrost erosion has been worsening for years
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The Arctic is warming faster than any other region on the planet. As a result, permafrost that is thousands of years old is now being lost to erosion. As measurements gathered on the Lena River by AWI experts show, the scale of erosion is alarming: every year, roughly 15 metres of the riverbanks crumble away. In addition, the carbon stored in the permafrost could worsen the greenhouse effect.
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Today, the permafrost soils found on the Arctic coasts of Canada, Russia and Alaska, frozen for thousands of years, are increasingly eroding away due to the effects of waves and river currents -- especially because the warm season there is steadily growing longer. As experts from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have determined, this thawing has now taken on enormous proportions. By conducting a detailed analysis of historical satellite images from Siberia, Matthias Fuchs and his team were able to show that permafrost erosion in the Lena Delta has steadily worsened since the 1960s. Whereas in the 1960s the river, at a width of ca. 1.7 kilometres, gnawed away an average of five metres of land per year, between 2015 and 2018 that number rose to nearly 16 metres. In total the banks -- more in some places, less in others -- lost between 322 and 679 metres from 1965 to 2018.The researchers focused their efforts on the 1.5-kilometre-long Sobo-Sise Cliff, a steep yedoma cliff from which permafrost plummets into a branch of the Lena River. At its highest point, it is 27 metres tall -- as tall as a several-storey house. As Matthias Fuchs explains, "Major quantities of permafrost have been eroding away across the Arctic for many years now. Nevertheless, the Sobo-Sise Cliff is definitely a hotspot. There are very few other regions where the loss of land is so substantial." The worrisome aspect: the fact that the thawing and permafrost loss have intensified so massively in the last several years.Fuchs and his colleagues not only analysed satellite data; they also took a closer look at how much carbon and nitrogen are released every year by the erosion. The cliff's permafrost, which is ca. 50,000 years old and formed during the last Ice Age, consists of 88 percent ice. The remainder is mainly peat, silt and sand. Especially the peat, which consists of partially decomposed ancient mosses and sedges, contains a great amount of carbon and nitrogen, formerly stored in the plants. The AWI experts collected soil samples on site and then analysed their carbon and nitrogen content in the lab. "It's amazing that the Sobo-Sise Cliff contains so much organic material, even though it's predominantly composed of ice. On average, we find roughly 26 kilograms of carbon and two kilograms of nitrogen per cubic metre." That means from 2015 to 2018 alone, ca. 15,000 metric tons of carbon and at least 1,000 metric tons of nitrogen landed in the Lena River, where they were washed away."Carbon and nitrogen are important nutrients for microorganisms," Fuchs explains. "Due to the erosion and thawing of permafrost, microorganisms now enjoy access to both." And this can have a number of consequences. When the microbes break down the carbon, they release carbon dioxide -- just like we humans do when we breathe. When that happens, the loss of permafrost worsens the greenhouse effect by 're-mobilising' carbon that was previously stored away. In addition, the intensive input of carbon and nitrogen in the Lena is changing the nutrient supply in its waters. "This could significantly influence, or even transform, the river's natural food webs," says Fuchs.The researchers can't yet say precisely what the consequences will be. To do so, in future studies they'll need to examine the nutrient flows in, and the biology of, the Lena river in more detail. But with their latest efforts and their assessment of the permafrost erosion, which has just been published in the journal
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Climate
| 2,020 |
September 16, 2020
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https://www.sciencedaily.com/releases/2020/09/200916113411.htm
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Can pumping up cold water from deep within the ocean halt coral bleaching?
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The risk of severe coral bleaching -- a condition in which corals lose their symbiotic algae, called zooxanthellae -- is five times more frequent today than it was forty years ago. Coral bleaching is a direct result of global warming, where rising temperatures cause marine heat waves, which place stress on the living coral animals, as well as the photosynthetic algae on which they depend for energy. This heat stress causes the algae to malfunction, at which point they are expelled by the corals, causing the organisms to lose their color and appear white (thus the term coral "bleaching").
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Due to the increasing pressure of global warming on highly valuable coral reef ecosystems, scientists are now seeking novel ways to decrease heat stress on corals. A new study led by Yvonne Sawall, assistant scientist at the Bermuda Institute of Ocean Sciences (BIOS), is showing potential for the use of artificial upwelling (AU) -- or the application of cooler, deep water -- as a way to mitigate the thermal stress on corals.Upwelling is a natural oceanographic process in which winds push surfaces waters away from a region, such as a coastline, allowing the uplift of deep, cold waters to the surface. These waters are typically rich in nutrients and form the basis of productive marine ecosystems which, in turn, support many of the world's most important commercial fisheries. AU is a geoengineering method that uses pumps to bring deep-ocean water to the surface. Originally designed to fertilize surface waters to increase fish stocks or carbon dioxide (CO"Ocean warming and the occurrence of heat waves will increase in frequency and intensity over the coming decades and we need to consider rather unconventional solutions to protect and sustain coral reefs," Sawall said.With funding from the German Research Foundation (DFG, with principal investigator Yuming Feng, doctoral student at the GEOMAR Helmholtz Center for Ocean Research in Kiel, Germany), Sawall and her co-authors studied three shallow water reef building coral species in Bermuda: After collecting fragments from living corals on Sea Venture Shoals, Bermuda, at a depth of 15 feet (5 meters), the research team placed the colonies in aquaria at BIOS to test the effects of deep cold-water pulses (AU) during thermal stress. Fragments were treated with various temperatures conditions, including an average summer temperature (28°C); a heat stress treatment known to cause bleaching (31°C); a heat stress treatment with daily pulses of cooler deep water from a depth of 164 feet (50 m, 24°C); and a heat stress treatment with daily pulses of cooler deep water from a depth of 300 feet (100 m, 20°C). The deep water used for the experiment was collected aboard the BIOS-operated research vessel (R/V) The results of the study showed that even short intrusions of cooler deep water (less than two hours per day) can mitigate thermal stress in corals. This was evident in higher levels of zooxanthellae performance in corals exposed to heat stress and AU compared to corals that were exposed to heat stress only, and this effect seemed stronger in the simulations with water from deeper depths."Our study shows the potential benefits of pulsed AU during heat waves. The next steps now are to find suitable AU settings to maximize the benefits, while minimizing potential harmful side effects of AU for corals and the ecosystem they support," Sawall said.
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September 16, 2020
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https://www.sciencedaily.com/releases/2020/09/200916113409.htm
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Mercury concentrations in Yukon river fish could surpass EPA criterion by 2050
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The concentration of mercury in the fish in Alaska's Yukon River may exceed the EPA's human health criterion by 2050 if greenhouse gas emissions that cause global warming are not constrained, according to scientific research funded in part by NASA. This first of its kind research estimates potential releases of mercury from thawing permafrost under high and low carbon emissions scenarios. The researchers predict that by 2200, the mercury emitted into both the atmosphere and water annually by thawing permafrost will compare with current global anthropogenic mercury emissions. That's because higher carbon emissions lead to faster and more atmosphere and water, where it can accumulate in wildlife like fish.
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The team's results were published Sept. 16 in "If we can hit the Paris Accord target, we expect minimal impacts to mercury concentrations in fish and water. If we continue with unconstrained greenhouse gas emissions, however, it is likely that we will see large increases in mercury concentrations," said Kevin Schaefer, a scientist at the National Snow and Ice Data Center (NSIDC) and lead researcher on the project. Mercury emissions of these magnitudes could have a global impact. "What happens in the Arctic does not stay in the Arctic," said Schaefer, "The mercury emissions from thawing permafrost could persist for centuries, impacting the environment both locally and globally."In 2018, Schaefer and several of his colleagues found that permafrost soils store nearly twice as much mercury as all other soils, the ocean and the atmosphere combined. That work was funded by NASA as part of the Arctic-Boreal Vulnerability Experiment (ABoVE), a major effort to improve understanding of how climate change is affecting Arctic ecosystems, and how those changes ultimately affect people and places in the Arctic and beyond. Now, the researchers have created a model -- which relies in part on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Terra satellite -- to predict how mercury emissions from thawing Arctic permafrost will change under different global emissions scenarios.The new paper characterizes the release of mercury from thawing permafrost for high and low carbon emissions scenarios based on two of the four Representative Concentration Pathways (RCPs) from the Intergovernmental Panel on Climate Change's Fifth Assessment Report (AR5). The high carbon emissions scenario (RCP 8.5) assumes unconstrained "business as usual" emissions, while the low carbon emissions scenario (RCP 4.5) assumes carbon emissions consistent with the Paris Agreement global target of less than 2 degrees Celsius of warming above pre-industrial levels.The results indicate minimal impacts to mercury concentrations in water and fish for the low carbon emissions scenario and large increases for the high carbon emissions scenario. At the global level, the high carbon emissions scenario would significantly increase the amount of mercury released into the atmosphere, where it would persist in the environment for centuries. At a local level, this would result in large increases to mercury concentrations in fish and water in the Yukon River. For the high emissions scenario, mercury concentrations could double in the Yukon River by 2100. The low carbon emissions scenario shows minimal mercury releases to the atmosphere and small changes to mercury concentrations in fish and water. For the low emissions scenario, mercury concentrations would likely increase by only about 14 percent and would not exceed EPA criterion by 2300."The thaw of permafrost due to climate change may release mercury as well as greenhouse gases like methane. We need to comply with the Paris Accord target of 2 degrees C. Otherwise, under a high emission scenario, a significant portion of mercury will be released to the environment, and it will continue for hundreds of years," said Yasin Elshorbany, a co-author on the study from the University of South Florida St. Petersburg campus.The Yukon River is the fifth largest drainage basin in North America and home to one of the world's longest salmon runs. It serves as an important commercial and subsistence fishery.
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Climate
| 2,020 |
September 15, 2020
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https://www.sciencedaily.com/releases/2020/09/200915105951.htm
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Satellite images display changes in the condition of European forests
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Rupert Seidl (Professor of Ecosystem Dynamics and Forest Management in Mountain Landscapes at TUM) and his colleague Cornelius Senf (lead author of the study) for the first time produced a high-resolution map of all openings in the canopy of European forests. They have analyzed more than 30,000 satellite images and identified more than 36 million areas where large trees have given way to open spaces of young trees. This corresponds to a loss of the canopy in 17 percent of the European forests in 30 years.
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The reasons for the canopy openings range from regulated wood use to wind storms and forest fires. The team also found that the size of the canopy openings varied widely from area to area.For example, Sweden has the largest canopy openings (averaging almost two hectares) while Portugal has the highest number of canopy openings. Switzerland has the smallest openings with just 0.6 hectares on average (which is smaller than a soccer field) while the average size opening in Germany is 0.7 hectares and in Italy 0.75 hectares. The largest opening documented by the researchers is in Spain, where a single fire in 2012 burned 17,000 hectares.The novel map the team has created also makes it possible to describe changes in forest conditions. The researchers have found, for example, that throughout Europe forests have become more open and the frequency of forests being interrupted by open spaces has increased. In addition, the openings themselves on average have increased in size primarily due to wind storms and forest fires in recent years.In such areas, however, the tendency is that more trees are surviving due to the availability of seed material. This, in turn, promotes the recovery of forests after a disturbance and can be seen as an indication of the increase in low-intensity forestry in Europe, where only single trees or crops of trees are taken rather than clear cutting large areas.Therefore, despite the major changes in Europe's forests, the researchers see positive developments. As Cornelius Senf has said, "In most cases, new, young trees grow up after a loss of the old stand." However, he goes on to say: "To understand where forests may be at risk of irreversible damage, we need a baseline as a reference. This is provided by the newly created map."Professor Rupert Seidl adds: "The new maps help us to understand how Europe's forests are changing. After all, increasing opening in the canopy pose a risk to the forest, but also other opportunities for new generations of trees that are better adapted to climate change to establish themselves. Among other things, the maps can help to identify areas where regeneration needs to be promoted through targeted planting or where the forests can rejuvenate themselves. In this way, the forest can be made fit for climate change -- a task that, especially in the last two years, has gained in urgency."
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Climate
| 2,020 |
September 15, 2020
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https://www.sciencedaily.com/releases/2020/09/200915090110.htm
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Ocean algae get 'coup de grace' from viruses
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Scientists have long believed that ocean viruses always quickly kill algae, but Rutgers-led research shows they live in harmony with algae and viruses provide a "coup de grace" only when blooms of algae are already stressed and dying.
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The study, published in the journal "It's only when the infected algal cells become stressed, such as when they run out of nutrients, that the viruses turn deadly," said lead author Benjamin Knowles, a former post-doctoral researcher in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick who is now at UCLA. He was also a post-doctoral fellow at Rutgers' Institute of Earth, Ocean, and Atmospheric Sciences. "We feel that this entirely new model of infection is widespread in the oceans and stands to fundamentally alter how we view host-virus interactions and the impact of viruses on ecosystems and biogeochemical cycling since it goes against the long-accepted classic model of viruses always being lethal and killing cells."Biogeochemical cycling refers to essential nutrients like carbon, oxygen, nitrogen, phosphorus, calcium, iron and water circulating through organisms and the environment. The coccolithophore algae The scientists studied virus-algae interactions in the lab and in controlled, mini-blooms in coastal waters of Norway. They focused on viral infection of a form of algae that is responsible for generating much of the oxygen and carbon cycling on Earth. A group of ocean viruses called coccolithoviruses routinely infect and kill The viruses eventually rupture algal cells, contributing to the global food web by making energy and organic matter available to other organisms. But infected cells don't die right away, the scientists discovered. Instead, infected cells multiply and bloom across dozens of miles of ocean waters and die in a coordinated manner. These dynamics have been routinely observed in previous studies but couldn't be explained by the rate at which algal hosts and viruses encounter each other in nature."The algae and viruses have a quasi-symbiotic type of relationship, allowing both algal cells and viruses to replicate happily for a while," said senior author Kay D. Bidle, a professor and microbial oceanographer in the Department of Marine and Coastal Sciences at Rutgers-New Brunswick and the Institute of Earth, Ocean, and Atmospheric Sciences. "We feel that these newly discovered dynamics also apply to other virus-algal interactions across the oceans and are fundamental to how infection works. By combining experimental, theoretical and environmental approaches, our work presents a template to diagnose this type of infection in other systems."The algae-virus dynamics have important implications for the outcome of infections and the flow of carbon and may lead to scenarios where carbon dioxide is sequestered, or stored, in the deep ocean rather than retained in the upper ocean, Bidle said. Further research is needed to fully understand the extent of these dynamics and their impacts on ecosystems and the cycling of carbon in the oceans.
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Climate
| 2,020 |
September 14, 2020
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https://www.sciencedaily.com/releases/2020/09/200914172931.htm
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Ancient volcanoes once boosted ocean carbon, but humans are now far outpacing them
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A new study of an ancient period that is considered the closest natural analog to the era of modern human carbon emissions has found that massive volcanism sent great waves of carbon into the oceans over thousands of years -- but that nature did not come close to matching what humans are doing today. The study estimates that humans are now introducing the element three to eight times faster, or possibly even more. The consequences for life both in the water and on land are potentially catastrophic. The findings appear this week in the journal
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Researchers at Columbia University's Lamont-Doherty Earth Observatory examined ocean conditions 55.6 million years ago, a time known as the Paleocene-Eocene Thermal Maximum (PETM). Before this, the planet was already considerably warmer than it is today, and the soaring COScientists have known about the PETM carbon surge for years, but until now, have been shaky on what caused it. Aside from volcanism, hypotheses have included the sudden dissolution of frozen methane (which contains carbon) from ocean-floor muds, or even a collision with a comet. Researchers have also been uncertain about how much carbon dioxide was present in the air, and thus how much the oceans took in. The new study solidifies both the volcano theory, and the amount of carbon that was released into the air.The research is directly relevant to today, said lead author Laura Haynes, who did the research as a graduate student at Lamont-Doherty. "We want to understand how the earth system is going to respond to rapid COUp to now, marine studies of the PETM have relied on scant chemical data from the oceans, and assumptions based on a certain degree of guesswork that researchers fed into computer models.The authors of the new study got at the questions more directly. They did this by culturing tiny shelled marine organisms called foraminifera in seawater that they formulated to resemble the highly acidic conditions of the PETM. They recorded how the organisms took up the element boron into their shells during growth. They then compared these data with analyses of boron from fossilized foraminifera in Pacific and Atlantic ocean-floor cores that span the PETM. This allowed them to identify carbon-isotope signatures associated with specific carbon sources. This indicated that volcanoes were the main source -- probably from massive eruptions centered around what is now Iceland, as the North Atlantic ocean opened up, and northern North America and Greenland separated from northern Europe.The researchers say the carbon pulses, which others estimate lasted for at least 4,000 to 5,000 years, added as much as 14.9 quadrillion metric tons of carbon to the oceans -- a two-thirds increase over their previous content. The carbon would have come from COToday, human emissions are causing carbon dioxide in the atmosphere to skyrocket, and the oceans are again absorbing much of it. The difference is that we are introducing it much faster than the volcanoes did -- within decades instead of millennia. Atmospheric levels have shot up from about 280 parts per million in the 1700s to about 415 today, and they are on a path to keep rising rapidly. Atmospheric levels would already be much higher if the oceans were not absorbing so much. As they do, rapid acidification is starting to stress marine life."If you add carbon slowly, living things can adapt. If you do it very fast, that's a really big problem," said the study's coauthor Bärbel Hönisch, a geochemist at Lamont-Doherty. She pointed out that even at the much slower pace of the PETM, marine life saw major die-offs. "The past saw some really dire consequences, and that does not bode well for the future," she said. "We're outpacing the past, and the consequences are probably going to be very serious."
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Climate
| 2,020 |
September 14, 2020
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https://www.sciencedaily.com/releases/2020/09/200914151156.htm
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Antarctica: Cracks in the ice
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In recent years, the Pine Island Glacier and the Thwaites Glacier on West Antarctica has been undergoing rapid changes, with potentially major consequences for rising sea levels. However, the processes that underlie these changes and their precise impact on the weakening of these ice sheets have not yet been fully charted.
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A team of researchers including some from TU Delft has now investigated one of these processes in detail: the emergence and development of damage/cracks in part of the glaciers and how this process of cracking reinforces itself. They are publishing about this in the The researchers have combined satellite imagery from various sources to gain a more accurate picture of the rapid development of damage in the shear zones on the ice shelves of Pine Island and Thwaites. This damage consists of crevasses and fractures in the glaciers, the first signs that the shear zones are in the process of weakening. Modelling has revealed that the emergence of this kind of damage initiates a feedback process that accelerates the formation of fractures and weakening.According to the researchers, this process is one of the key factors that determines the stability -- or instability- of the ice sheets, and thus the possible contribution of this part of Antarctica to rising sea levels. They are calling for this information to be taken into account in climate modelling, in order to improve predictions of the contribution these glaciers are making to rising sea levels.Read more at:
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Climate
| 2,020 |
September 14, 2020
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https://www.sciencedaily.com/releases/2020/09/200914131918.htm
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Dams exacerbate the consequences of climate change on river fish
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A potential response of river fish to environmental changes is to colonize new habitats. But what happens when dams and weirs restrict their movement? And are native and alien species similarly affected? Researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and the Spanish University of Girona (UdG) have addressed these questions in a recent study.
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River ecosystems are frequently fragmented by dams and weirs. As a result, native fish are often restricted in their movement along the river course and are unable to colonize new habitats. Thus, barriers impede native species from adjusting their distributions in response to the effects of climate change such as changes in water temperature and quality.On the other hand, river fragmentation might also limit the further spread of invasive alien species. Using the Ebro River in Spain as an example, the research team has investigated how habitats of native and alien fish species change under different climate scenarios and how dams mediate habitat accessibility."The Ebro River is particularly vulnerable and threatened by climate change and species invasions. In addition, the Ebro River is fragmented by over 300 dams and many smaller barriers, which makes it even worse for the native fish species," said Emili García-Berthou, Professor at the University of Girona and co-author of the study.By applying a spatial modelling framework, the authors showed that losses of native species and gains of alien species and consequentially most pronounced biodiversity changes are particularly expected in the lower and mid reaches of larger Ebro River tributaries. According to their results, the majority of species are projected to shift their range in upstream direction with alien species such as eastern mosquitofish, wels catfish and common carp showing especially large habitat gains."The Ebro River system is home to several endemic species that exclusively occur on the Iberian Peninsula. These species are particularly imperilled by barriers that limit movements in response to climate change. Whether dams can effectively prevent the spread of alien species is questionable. In fact, the establishment of alien fishes is often facilitated by the changed flow and habitat conditions that result from damming rivers," said IGB researcher Johannes Radinger, lead author of the study.The results clearly show that fish communities in highly fragmented rivers affected by climate change will be particularly affected by biodiversity changes and species loss in the future. "Effective conservation of fishes should focus on the restoration of habitats and the natural flow regime, improvements of connectivity for native species and the control of alien species, particularly the prevention of further introductions," concluded the authors.
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Climate
| 2,020 |
September 14, 2020
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https://www.sciencedaily.com/releases/2020/09/200914115909.htm
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ARPA-type funding gives green technology an 'innovation advantage', study finds
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A new analysis of the successes and failures of green energy companies in the US has found that those with ARPA funding filed for far more patents in the years after launching than other "cleantech" startups from the same time.
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The "innovation advantage" bestowed by ARPA-E -- an energy version of the legendary DARPA (Defense Advanced Research Projects Agency) -- was not shared by startups funded via other US government initiatives.ARPA-type agencies were developed in the US to fund "high risk, high reward" research with the aim of fostering major breakthroughs, often by providing greater freedom to take on highly ambitious technical challenges.The new findings offer encouragement to a UK government considering its own British ARPA (or 'BARPA'), but any agency adopting this model requires a focus in order to flourish -- and BARPA's should be climate, argues Professor Laura Diaz Anadon from the University of Cambridge."Our US-based research points to the value of ARPA agencies. The UK may well benefit from such an approach in a post-pandemic world, given the technological capital within its universities and private sector," said Anadon, co-author of the US innovation study."The UK should adapt the ARPA model to create an agency for the climate challenge as part of any Covid-19 recovery package. Focusing research and development on next-generation energy storage and renewables, and solutions for decarbonizing shipping, aviation and construction, could boost productivity and deliver large benefits to society," said Anadon.Dr Anna Goldstein, first author of the study from the University of Massachusetts Amherst, said: "ARPA is not a one-size-fits-all solution. ARPA agencies are mission-focused, and there is no evidence to suggest this model would work well as a fund for general science and technology."The research was conducted by the University of Cambridge, UK (Prof. Laura Diaz Anadon), the University of Massachusetts Amherst, US (Dr. Anna Goldstein and Prof. Erin Baker), and the Technical University of Munich in Germany (Prof. Claudia Doblinger). It is published today in the journal ARPA-E was established at the US Department of Energy under Obama, using a portion of the economic stimulus package that followed the 2009 financial crisis. To date, it has allocated US$3.38 billion.The aim was to accelerate innovation in "clean" technologies such as biofuels, smart grids and solar power at a time when it was out of favour with Venture Capital investors, due in part to long development cycles and low initial returns.For the latest study, researchers investigated whether ARPA-E -- a "posterchild" of mission-orientated innovation now under threat from the Trump administration -- had translated its unique approach into real-world success.By constructing a database of 1,287 US cleantech startups, and using patents as a proxy for innovation, they found that companies funded by a fledgling ARPA-E in 2010 went on to file patents at an average of twice the rate of other green energy companies in the years that followed.The researchers also measured "business success" by looking at how many companies were taken public or acquired by larger firms, as well as levels of private VC funding and overall survival rates.While ARPA-funded companies do better than those turned down by ARPA-E, in general they fare no better or worse than other cleantech startups with the same amount of patents and private funding before 2010.As such, the researchers argue that ARPA-E support alone does not bridge the "valley of death": the phase between initial funding injection and revenue generation during which startups often fold.Goldstein said: "It appears that ARPA-E helps startups working on riskier but potentially more disruptive technologies to reach the same levels of success as other, less risky, cleantech firms.""However, there is still a need for public funding to bring innovations in clean technology through the 'valley of death' so they can become commercial products that compete with legacy technologies and reduce emissions."Writing for Cambridge Zero, the University's new climate change initiative, Laura Diaz Anadon points out that, at just 1.7% of GDP, the UK lags in R&D investment: below the EU28 average, and way behind the US, South Korea and Japan."While the UK dramatically increased energy investment over the last 20 years, it is still below the levels this country saw in the 1970s and 1980s," said Anadon, Professor of Climate Change Policy at the University of Cambridge."My co-authors and I would recommend trialing a UK version of ARPA-E that can ramp up energy innovation, and support selected projects through to demonstration phase. R&D investments in energy transition would be an inexpensive but essential component of a Covid-19 recovery package.""The UK has solid recent experience in the energy space, but in the past several initiatives have fallen prey to volatile government funding before success can be properly gauged. Future efforts will need consistency as well as a set up that would enable state-of-the-art and independent evaluation."
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Climate
| 2,020 |
September 14, 2020
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https://www.sciencedaily.com/releases/2020/09/200914112233.htm
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Mediterranean and tropical biodiversity most vulnerable to human pressures
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Animals in tropical and Mediterranean areas are the most sensitive to climate change and land use pressures, finds a new study by UCL researchers.
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The findings, published today in Lead author Dr Tim Newbold (UCL Centre for Biodiversity & Environment Research) said: "Tropical areas are expected to see the greatest expansions of agriculture in the coming decades, and are already seeing new temperature extremes."Coupled with the fact that data on biodiversity are often biased towards more temperate regions, our findings suggest that global biodiversity declines may be even worse than leading experts are predicting. Urgent action is needed to prevent biodiversity losses and extinctions, particularly in tropical and Mediterranean areas which have some of the most diverse ecological communities on the planet."The research team analysed data on 47,044 species of animals, plants and fungi at thousands of sites in 91 countries to measure the number of different species living in more disturbed environments such as cities and intensive agricultural areas, or in moderately disturbed or wild spaces. The team also compared data on where species are able to survive against regional climate modelling data to predict responses to climate change.The researchers found substantially lower biodiversity in more disturbed environments, especially in Mediterranean and tropical regions. They also found that among vertebrates, those most sensitive to climate warming are found in tropical forests, tropical grasslands and Mediterranean areas. Species of concern include the eastern gorilla, critically endangered due to habitat loss and climate change in the African tropics, and Hermann's tortoise, a Mediterranean animal currently threatened by habitat loss and likely climate change as well in years to come.Across species in tropical regions, the researchers projected local declines of 10 to 13% in the number of species for each degree of climate warming.Species in areas with less pronounced seasonal changes, particularly in the tropics, were found to be the most vulnerable to climate change. The researchers note that plants and animals that have not adapted to wide ranges of temperatures across seasons are more likely to suffer if temperatures rise. In tropical and Mediterranean regions, many species were found to be already living near the upper temperature limit that they can tolerate.One partial explanation for the findings is that some other biomes (communities of plants and animals occupying a particular habitat) have been heavily influenced by humans for centuries, indicating that the most sensitive species are likely to have already been wiped out.While not tested in the study, the researchers say that tropical species may also be more vulnerable due to smaller range sizes and high concentrations of specialist species, as well as those that mature more slowly and produce fewer offspring.Dr Newbold said: "We found that areas facing the greatest biodiversity threats from climate change and land use were often the same areas, which is even more concerning as these two pressures can interact to make environments even more inhospitable. For example, heavily modified landscapes often have less canopy cover which would otherwise moderate extreme temperatures."Dr Newbold is also a co-author of the World Wildlife Fund's Living Planet Report, published this month, which showed that biodiversity has declined most in the tropics since 1970. He and colleagues argue that coordinated global efforts are needed to turn the tide of biodiversity loss."Conservation efforts alone will not be enough to save endangered and vulnerable animals and plants. Governments, private companies and consumers will all need to act now to curb climate change and to mitigate land use pressures that destroy habitats," he said.Dr Newbold and his study co-authors, UCL master's student Philippa Oppenheimer and PhD candidates Adrienne Etard and Jessica Williams, were supported by the Royal Society.
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Climate
| 2,020 |
September 14, 2020
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https://www.sciencedaily.com/releases/2020/09/200914112228.htm
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Climate change triggers migration, particularly in middle-income countries
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Environmental hazards affect populations worldwide and can drive migration under specific conditions. Changes in temperature levels, increased rainfall variability, and rapid-onset disasters, such as tropical storms, are important factors as shown by a new study led by the Potsdam Institute for Climate Impact Research (PIK). Environmental migration is most pronounced in middle-income and agricultural countries but weaker in low-income countries, where populations often lack resources needed for migration. The findings make it possible to identify geographical regions that may be especially susceptible to migration movements in the future.
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"Environmental factors can drive migration, but the size of the effects depends on the particular economic and sociopolitical conditions in the countries," says lead author Roman Hoffmann from PIK and the Vienna Institute of Demography of the Austrian Academy of Sciences. "In both low and high income countries environmental impacts on migration are weaker -- presumably because either people are too poor to leave and become basically trapped, or, in wealthy countries, have enough financial means to absorb the consequences. It is mainly in regions with middle incomes and a dependency on agriculture that we see strong effects."The meta-study, which analyzed 30 previously published studies on the topic, reveals a number of fascinating patterns. It shows, for example, that impacts on migration vary by types of environmental hazards and that different hazards can re-inforce each other. "While changing temperatures in a region are found to have the strongest impact on migration, also rapid-onset disasters and changing rainfall variability and anomalies can play a role. Especially smallholder farmers rely on steady climatic conditions and suffer from changes and shocks as they have insufficient capacities to adapt," says co-author Raya Muttarak from the International Institute of Applied Systems Analysis and the Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/ÖAW, University of Vienna).The researchers emphasize that there is no automatism at play -- environmental migration always depends on a number of economic and sociopolitical factors. The narrative of climate refugees pushing towards Europe or the US may be too simplistic. For instance, the researchers found compelling evidence that environmental changes in vulnerable countries predominantly lead to internal migration or migration to other low- and middle-income countries, rather than cross-border migration to high-income countries. Affected populations often migrate to places within their own region and eventually return to their homes within a relatively short period of time.The findings, published in the latest issue of Given the expected rise of the global average temperature the researchers believe that the topic of environmental migration will become more important in the future. Consequently, interventions have to be tailored to the actual situations on the ground that reduce vulnerabilities. "The best way to protect those affected is to stabilize the global climate, namely to rapidly reduce greenhouse gas emissions from burning fossil fuels," concludes Jesus Crespo Cuaresma from the Vienna University of Economics and Business and IIASA. "While migration can be an effective adaptation strategy for households, it can be involuntary and come with unacceptable human suffering -- unacceptable because it indeed can be avoided."
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Climate
| 2,020 |
September 14, 2020
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https://www.sciencedaily.com/releases/2020/09/200911093018.htm
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More than 90 percent of protected areas are disconnected
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Ongoing land clearing for agriculture, mining and urbanisation is isolating and disconnecting Earth's protected natural areas from each other, a new study shows.
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Lead author Michelle Ward, from The University of Queensland's School of Earth and Environmental Sciences, said the findings were "alarming.""Protected areas are vital for the protection and survival of plants, animals and ecosystems," Ms Ward said."When intact, healthy habitat connects these protected areas, species can migrate, escape danger such as fires, and track their preferred microclimates under rapid climate change."Our research shows 40 per cent of the terrestrial planet is intact, but only 9.7 per cent of Earth's terrestrial protected network can be considered structurally connected."This means more than 90 per cent of protected areas are isolated, in a sea of human activities."The study shows that, on average, 11 per cent of each country and territory's protected area estate can be considered connected.Under international agreements, the global protected area network must be well connected and cover 17 per cent of land.The study revealed, however, that only nine countries and territories -- 4.6 per cent of them -- have greater than 17 per cent of their land protected, and maintain greater than 50 per cent connectivity."On a positive note, our study provides a common framework -- previously absent -- for countries and territories to assess the connectivity performance of their existing and future protected areas, with access to information and metrics," Ms Ward said.Professor James Watson of UQ and the Wildlife Conservation Society said the research highlighted the importance of better locating future protected areas and the need for more emphasis on wide-scale habitat protection and restoration."Protected areas increasingly are becoming the only tool conservationists talk about, but most nature lives beyond the protected area boundary," Professor Watson said."We need national and global conservation goals that address whole-of-landscape conservation and targets that halt the destruction of habitat between protected areas."Most of nature has no chance if it's to survive in just 20 per cent of the world."We hope this study provides essential information for conservation and development planning, helping guide future national and global conservation agendas."
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Climate
| 2,020 |
September 11, 2020
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https://www.sciencedaily.com/releases/2020/09/200911093012.htm
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Climate change recasts the insect communities of the Arctic
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Through a unique research collaboration, researchers at the University of Helsinki have exposed major changes taking place in the insect communities of the Arctic. Their study reveals how climate change is affecting small but important predators of other insects, i.e. parasitoids.
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"Predators at the top of the food web give us a clue to what is happening to their prey species, too. These results increase our understanding of how global warming is changing nature. At the same time, they suggest new inroads for finding answers to big questions in the field of ecology," says Professor Tomas Roslin from the University of Helsinki and the Swedish University of Agricultural Sciences (SLU).The researchers' main discovery was that clear traces of climate change can already be seen in arctic insect communities."In areas where summers are rapidly warming, we find a higher proportion of cold-sensitive predators than we might expect based on the previous climate," Roslin notes.The study joined research teams working in Greenland, Canada, Russia, Norway, Finland and Iceland, which together compared regions where the climate has changed at different rates and in different ways in recent decades."The climate of the Arctic is currently changing about twice as fast as the global average. Therefore, the Arctic region provides an important laboratory when we try to understand the effects of climate change on nature," says Tuomas Kankaanpää, lead author of the study and active at the Faculty of Agriculture and Forestry, University of Helsinki."To distinguish the key consequences of climate change, we have focused on some of the most important predators in the Arctic, parasitoid wasps and flies. These parasitoids are predators whose larvae develop on or within a single host individual and usually kill it in the process. And now we have found that climate change is dramatically affecting the relative dominance of different types of parasitoids."The researchers found that the changes particularly affect the ratios between parasitoids adhering to different lifestyles. On the other hand, different parasitoid species use different hosts. In the Arctic, Lepidoptera i.e. butterflies and moths and Diptera such as flies and gnats are the largest host groups of the parasitoids. Diptera are more dominant towards the north, while the species richness of Lepidoptera increase towards the south."We have found that the proportion of parasitoids preying on warmth-loving butterflies is especially in areas where summer temperatures in particular have risen in recent decades. By contrast, winter-time warming is reflected in a large representation of parasitoid species feeding on Diptera," says Kankaanpää."Beyond their host species, parasitoids can also be classified into two other groups based on how they use their host. Koinobionts are the true masters of the parasitic lifestyle and manipulate their host with surgical precision. Females lay their eggs in the host's egg or larva, where the parasitoid larva then waits patiently until the host has grown larger. To do this, the koinobiont must skillfully manipulate the host's immune defense to survive. The second group, idiobionts, are more reminiscent of classic predators. The larvae of idiobionts start eating the host as soon as they hatch," says Kankaanpää."These different strategies are directly reflected in the sensitivity of the two groups to climatic conditions. Koinobionts can wait until the host has retreated to sheltered conditions to hibernate before killing it. Thus, they get protection from the worst frosts. Idiobionts lack this advantage, and often paralyze the host where found, having to then live in it at the mercy of the weather.""In our project, we have harnessed the ratio between parasitoids of Lepidoptera and Diptera, and between koinobionts and idiobionts, into a sensitive barometer of the effects of climate change, Kankaanpää says. To this end, we have adopted a number of effective solutions. A common approach to predicting the effects of climate change is to compare contemporary communities of organisms in different climates. We then assume that communities in cold areas will eventually begin to resemble their current counterparts in warmer regions as the climate warms. The time dimension of change is thus replaced by distance, in what is called a space for time substitution. Now, however, we can already compare areas where the climate has changed in different ways. This is especially true in the Arctic, where change, and at the same time regional disparities, are large," says Kankaanpää.Professor Tomas Roslin has been the supervisor of Tuomas Kankaanpää and is equally enthusiastic about new ways of research -- and also points out another advance."For studies like this, we are also cooperating in a new way. This allows us to ask questions that would otherwise be too expensive, difficult and logistically challenging to address. If one research team was to send its members around the world, it would cost hundreds of thousands of euros. But by collaborating with other scientists across the Arctic and asking them for a few working days, everyone can provide their piece of the bigger puzzle, as collected using uniform methods. This is how we put together the full picture with realistic resources. And I am convinced that this kind of collaboration will pave the way for new breakthroughs," Roslin says.With their clever and slightly macabre lifestyles, parasitoids have inspired us humans as well. The monsters in the Alien movies are classical parasitoids which, just like some parasitic flies, leave their eggs waiting for a passing host. Due to their cruel appearance, parasitoid wasps are often despised. But at the same time, we have the parasitoids to thank for our crops and gardens. Parasitoids are among the main enemies of herbivorous insects, and without them much of the world's greenery could disappear into smaller mouths. In the Arctic, the parasitoids are, in fact, the most numerous and species-rich predators.
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Climate
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September 11, 2020
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https://www.sciencedaily.com/releases/2020/09/200911093010.htm
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Heated rivalries for pollinators among Arctic plants
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Insect pollination is as important to Arctic plants as it is to plants further south. When flowers abound, the plants have to compete for pollinators. Researchers at the University of Helsinki reveal that higher temperatures cause the flowering periods of different plant species to pile up in time. As a consequence, climate change may affect the competitive relationships of plants.
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The most attractive plant species steal the majority of pollinators, making other plants flowering at the same time suffer from poorer pollination."Most flowering plants are dependent on the pollination services provided by insects. Thus, plants need to time their flowering to periods of maximal pollinator abundances. On the other hand, plant species compete with each other for pollination. Thus, plant species flowering at the same time can affect each other's pollination success. Temperature is one of the most important environmental determinants of the onset of flowering. As the climate warms, plant species change their flowering periods, thereby changing their competition for pollinators," explains Mikko Tiusanen, researcher at the Faculty of Agriculture and Forestry, University of Helsinki, and lead scientist behind the study."We have been studying the relationship between plants and pollinators in North East Greenland, where the climate is warming twice as fast as the global average. The most common flowering plant in this region is Avens, a widespread and abundant flowering species. The shape of an Avens' flower is an open, white cup of nectar, irresistibly attractive to any pollinators around. In our comparisons, Avens was found to attract many more visitors than other plant species. When in bloom, it thus monopolizes insect pollination services at the expense of other plants in flower," says Tiusanen.By studying the timing of flowering of different plant species under different environmental conditions, the researchers found that higher temperatures caused the flowering periods of different plant species to contract. In particular, the flowering of the Moss Campion advanced relative to the flowering of Avens. This affects the competition between the two species, since the flowering of Avens is directly reflected in how many insects carry Campion pollen: with more Avens in bloom, fewer insects carried the pollen of the Campion.Global warming may thus affect competition between plant species for pollination services, thereby changing interactions between species. For example, overlap in flowering between a plant species and a more attractive competitor reduces pollination and may impair the species' chances of survival in the long run. This is likely to be a particular threat to rare plant species, as well as to flower species less attractive to insects, scientists speculate."To me, the Arctic represents a planetary research laboratory for studies of climate change," says Tomas Roslin, director of the research group spanning the University of Helsinki and the Swedish University of Agricultural Sciences (SLU). "The climate of this region is now changing twice as fast as the global average. What this means is that what happens in the Arctic today may later occur in the rest of the world. At the same time, relatively low species richness in the Arctic allows us to resolve their interactions in great detail. But scientific reasons are only half the arctic appeal. Northeast Greenland is one of the most beautiful areas in the world, and at the same time one of the largest uninhabited areas in the world. When studying insects here, you may even run into a polar bear. Such a combination keeps the researchers alert and awake."
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Climate
| 2,020 |
September 10, 2020
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https://www.sciencedaily.com/releases/2020/09/200910171824.htm
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Dietary changes could produce big offsets to carbon emissions
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Eating less meat and dairy products in favor of plant-based proteins like those found in grains, legumes and nuts could make a huge difference in how much carbon dioxide reaches the atmosphere, research by Oregon State University shows.
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Published Monday in "Plant protein foods provide important nutrients while requiring a small percentage of the farm and ranch land needed to generate animal products like beef, pork and milk," said Ripple, distinguished professor of ecology in the Oregon State College of Forestry.Via photosynthesis, trees and other vegetation generate energy from sunlight, water and carbon dioxide, in the process storing some of the carbon in the form of wood and foliage and releasing oxygen.The land required to meet current global demand for meat and dairy-based products constitutes more than 80% of the Earth's agricultural acreage, according to the research collaboration led by Matthew Hayek of New York University.If production is shifted to more land-friendly foods, the door opens to the regrowth of native vegetation capable of scrubbing away years of climate-changing fossil fuel emissions.The scientists mapped and analyzed areas where extensive production of animal-sourced foods is likely suppressing forests and other native vegetation. They identified areas totaling more than 7 million square kilometers -- roughly the size of Russia -- with conditions such that forests would regrow and thrive on their own if agricultural pressure were removed.Atmospheric carbon dioxide has increased 40% since the dawn of the industrial age, contributing heavily to a warming planet. According to the National Atmospheric and Oceanic Administration, the global average atmospheric carbon dioxide concentration in 2018 was 407.4 parts per million, higher than at any time in at least 800,000 years.Fossil fuels like coal and oil contain carbon that plants pulled out of the atmosphere through photosynthesis over millions of years. That same carbon is now being returned to the atmosphere in a matter of hundreds of years because fossil fuels are being burned for energy,The annual rate of increase in atmospheric COUnlike oxygen or nitrogen, which account for most of the atmosphere, greenhouse gases absorb heat and release it gradually over time. Absent those greenhouse gases, the planet's average annual temperature would be below freezing rather than around 60 degrees Fahrenheit, but too-high levels of greenhouse gases cause the Earth's energy budget to become unbalanced.The largest potential for climate-benefiting forest regrowth is in comparatively wealthy nations. In those countries, cutbacks in meat and dairy production would bring relatively mild impacts on food security, the researchers say, while substantially assisting in capping climate change at 1.5 degrees Celsius above pre-industrial age levels as called for in the 2016 Paris Agreement.A majority of climate scientists agree that limiting warming to 1.5 degrees would maintain substantial proportions of ecosystems while also benefiting human health and economies."We can think of shifting our eating habits toward land-friendly diets as a supplement to developing green energy, rather than a substitute," Hayek said. "Restoring native forests could buy some much-needed time for countries to transition their energy grids to renewable, fossil-free infrastructure."Hayek, Ripple and their collaborators -- Helen Harwatt of Harvard and Nathaniel Mueller of Colorado State -- emphasize that their findings are meant to help local officials seeking to come up with plans to mitigate climate change. The scientists acknowledge that animal-based agriculture is economically and culturally important in many areas around the globe."While the potential for restoring ecosystems is substantial, extensive animal agriculture is culturally and economically important in many regions around the world," Mueller said. "Ultimately, our findings can help target places where restoring ecosystems and halting ongoing deforestation would have the largest carbon benefits."Reducing meat production would also aid water quality and quantity, wildlife habitat and biodiversity, Ripple says, including fostering the ecosystem health that helps thwart pandemic diseases originating from animals as COVID-19 is believed to have done."Intact, functioning ecosystems and preserved wildlife habitat help make the risk of pandemics smaller," Ripple said. "Our research shows that with diet change, we have an opportunity to give large areas back to nature and wildlife with relatively minimal impacts on food security. Ecosystem restoration and reduced livestock populations could reduce zoonotic disease transmission from wildlife to chickens or pigs and ultimately to people."
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Climate
| 2,020 |
September 10, 2020
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https://www.sciencedaily.com/releases/2020/09/200910150318.htm
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Loss of sea otters accelerating the effects of climate change
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The impacts of predator loss and climate change are combining to devastate living reefs that have defined Alaskan kelp forests for centuries, according to new research published in
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"We discovered that massive limestone reefs built by algae underpin the Aleutian Islands' kelp forest ecosystem," said Douglas Rasher, a senior research scientist at Bigelow Laboratory for Ocean Sciences and the lead author of the study. "However, these long-lived reefs are now disappearing before our eyes, and we're looking at a collapse likely on the order of decades rather than centuries."The coral-like reefs, built by the red alga "Ocean warming and acidification are making it difficult for calcifying organisms to produce their shells, or in this case, the alga's protective skeleton," said Rasher, who led the international team of researchers that included coauthors Jim Estes from UC Santa Cruz and Bob Steneck from University of Maine. "This critical species has now become highly vulnerable to urchin grazing -- right as urchin abundance is peaking. It's a devasting combination."Based on their size and age, it's clear that the massive reefs built by "During the fur trade, As the alga adds to its calcified skeleton each year, it creates bands of annual growth -- like rings in a tree. These bands archive whether sea urchin grazing events occurred in each year. By examining polished samples under a microscope, the research team found that they suddenly had a way to look back into the ecosystem's past. This insight allowed them to determine that urchin grazing had waned and waxed over time with the past recovery and recent collapse of sea otter populations. Alarmingly, it also revealed that grazing rates have accelerated in recent time in association with rising seawater temperatures.The researchers also brought live "It's well documented that humans are changing Earth's ecosystems by altering the climate and by removing large predators, but scientists rarely study those processes together," Rasher said. "If we had only studied the effects of climate change on The discovery of this interplay between predators and climate change does offer some hope -- providing multiple ways to address the accelerating reef destruction. Reducing greenhouse gases is one of humanity's most urgent needs, but it is a global effort that requires international cooperation and coordination. Restoring sea otters, however, is a regional effort that has the ability to mitigate reef erosion by urchins, and pull the ecosystem back from its tipping point."This is exciting because it suggests that resource managers have opportunities to manage large predators in ways that can help slow the rate with which climate change is deteriorating our natural ecosystems," Rasher said. "In the case of Aleutian kelp forests, restoring sea otter populations would bring many ecological benefits, and would also buy us time to get our act together on curbing carbon emissions, before this foundational reef builder is lost."
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Climate
| 2,020 |
September 10, 2020
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https://www.sciencedaily.com/releases/2020/09/200910150313.htm
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High-fidelity record of Earth's climate history puts current changes in context
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For the first time, climate scientists have compiled a continuous, high-fidelity record of variations in Earth's climate extending 66 million years into the past. The record reveals four distinctive climate states, which the researchers dubbed Hothouse, Warmhouse, Coolhouse, and Icehouse.
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These major climate states persisted for millions and sometimes tens of millions of years, and within each one the climate shows rhythmic variations corresponding to changes in Earth's orbit around the sun. But each climate state has a distinctive response to orbital variations, which drive relatively small changes in global temperatures compared with the dramatic shifts between different climate states.The new findings, published September 10 in "We've known for a long time that the glacial-interglacial cycles are paced by changes in Earth's orbit, which alter the amount of solar energy reaching Earth's surface, and astronomers have been computing these orbital variations back in time," explained coauthor James Zachos, distinguished professor of Earth and planetary sciences and Ida Benson Lynn Professor of Ocean Health at UC Santa Cruz."As we reconstructed past climates, we could see long-term coarse changes quite well. We also knew there should be finer-scale rhythmic variability due to orbital variations, but for a long time it was considered impossible to recover that signal," Zachos said. "Now that we have succeeded in capturing the natural climate variability, we can see that the projected anthropogenic warming will be much greater than that."For the past 3 million years, Earth's climate has been in an Icehouse state characterized by alternating glacial and interglacial periods. Modern humans evolved during this time, but greenhouse gas emissions and other human activities are now driving the planet toward the Warmhouse and Hothouse climate states not seen since the Eocene epoch, which ended about 34 million years ago. During the early Eocene, there were no polar ice caps, and average global temperatures were 9 to 14 degrees Celsius higher than today."The IPCC projections for 2300 in the 'business-as-usual' scenario will potentially bring global temperature to a level the planet has not seen in 50 million years," Zachos said.Critical to compiling the new climate record was getting high-quality sediment cores from deep ocean basins through the international Ocean Drilling Program (ODP, later the Integrated Ocean Drilling Program, IODP, succeeded in 2013 by the International Ocean Discovery Program). Signatures of past climates are recorded in the shells of microscopic plankton (called foraminifera) preserved in the seafloor sediments. After analyzing the sediment cores, researchers then had to develop an "astrochronology" by matching the climate variations recorded in sediment layers with variations in Earth's orbit (known as Milankovitch cycles)."The community figured out how to extend this strategy to older time intervals in the mid-1990s," said Zachos, who led a study published in 2001 in "That changed everything, because if we could do that, we knew we could go all the way back to maybe 66 million years ago and put these transient events and major transitions in Earth's climate in the context of orbital-scale variations," he said.Zachos has collaborated for years with lead author Thomas Westerhold at the University of Bremen Center for Marine Environmental Sciences (MARUM) in Germany, which houses a vast repository of sediment cores. The Bremen lab along with Zachos's group at UCSC generated much of the new data for the older part of the record.Westerhold oversaw a critical step, splicing together overlapping segments of the climate record obtained from sediment cores from different parts of the world. "It's a tedious process to assemble this long megasplice of climate records, and we also wanted to replicate the records with separate sediment cores to verify the signals, so this was a big effort of the international community working together," Zachos said.Now that they have compiled a continuous, astronomically dated climate record of the past 66 million years, the researchers can see that the climate's response to orbital variations depends on factors such as greenhouse gas levels and the extent of polar ice sheets."In an extreme greenhouse world with no ice, there won't be any feedbacks involving the ice sheets, and that changes the dynamics of the climate," Zachos explained.Most of the major climate transitions in the past 66 million years have been associated with changes in greenhouse gas levels. Zachos has done extensive research on the Paleocene-Eocene Thermal Maximum (PETM), for example, showing that this episode of rapid global warming, which drove the climate into a Hothouse state, was associated with a massive release of carbon into the atmosphere. Similarly, in the late Eocene, as atmospheric carbon dioxide levels were dropping, ice sheets began to form in Antarctica and the climate transitioned to a Coolhouse state."The climate can become unstable when it's nearing one of these transitions, and we see more deterministic responses to orbital forcing, so that's something we would like to better understand," Zachos said.The new climate record provides a valuable framework for many areas of research, he added. It is not only useful for testing climate models, but also for geophysicists studying different aspects of Earth dynamics and paleontologists studying how changing environments drive the evolution of species.Coauthors Steven Bohaty, now at the University of Southampton, and Kate Littler, now at the University of Exeter, both worked with Zachos at UC Santa Cruz. The paper's coauthors also include researchers at more than a dozen institutions around the world. This work was funded by the German Research Foundation (DFG), Natural Environmental Research Council (NERC), European Union's Horizon 2020 program, National Science Foundation of China, Netherlands Earth System Science Centre, and the U.S. National Science Foundation.
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Climate
| 2,020 |
September 10, 2020
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https://www.sciencedaily.com/releases/2020/09/200910130414.htm
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$500 billion question: What's the value of studying the ocean's biological carbon pump?
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The ocean plays an invaluable role in capturing carbon dioxide (CO
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A new paper published in the journal Using a climate economy model that factors in the social costs of carbon and reflects future damages expected as a consequence of a changing climate, lead author Di Jin of WHOI's Marine Policy Center places the value of studying ocean carbon sequestration at $500 billion."The paper lays out the connections between the benefit of scientific research and decision making," says Jin. "By investing in science, you can narrow the range of uncertainty and improve a social cost-benefit assessment."Better understanding of the ocean's carbon sequestration capacity will lead to more accurate climate models, providing policymakers with the information they need to establish emissions targets and make plans for a changing climate, Jin adds.With co-authors Porter Hoagland and Ken Buesseler, Jin builds a case for a 20-year scientific research program to measure and model the ocean's biological carbon pump, the process by which atmospheric carbon dioxide is transported to the deep ocean through the marine food web.The biological carbon pump is fueled by tiny plant-like organisms floating on the ocean surface called phytoplankton, which consume carbon dioxide in the process of photosynthesis. When the phytoplankton die or are eaten by larger organisms, the carbon-rich fragments and fecal matter sink deeper into the ocean, where they are eaten by other creatures or buried in seafloor sediments, which helps decrease atmospheric carbon dioxide and thus reduces global climate change.Rising carbon dioxide levels in the atmosphere, a result of human activity such as burning fossil fuels, warms the planet by trapping heat from the sun and also dissolves into seawater, lowering the pH of the ocean, a phenomenon known as ocean acidification. A warmer, more acidic ocean could weaken the carbon pump, causing atmospheric temperatures to rise -- or it could get stronger, with the opposite effect."When we try to predict what the world is going to look like, there's great uncertainty," says Buesseler, a WHOI marine chemist. "Not only do we not know how big this pump is, we don't know whether it will remove more or less carbon dioxide in the future. We need to make progress to better understand where we're headed, because the climate affects all of humanity."Buesseler added that efforts like WHOI's Ocean Twilight Zone initiative and NASA's EXport Processes in the global Ocean from RemoTe Sensing (EXPORTS) program are making important strides in understanding the ocean's role in the global carbon cycle, but this research needs to be vastly scaled up in order to develop predictive models such as those used by the Intergovernmental Panel on Climate Change (IPCC). Current IPCC models do not account for change in the ocean's ability to take up carbon, which Buesseler said affects their accuracy.Though the paper's assessment doesn't account for the cost of a global research program, Buesseler said that investment would be a small fraction of the $500 billion expected benefit. The authors warn that this savings could also be viewed as a cost to society if the research does not lead to policy decisions that mitigate the effects of climate change."Just like a weather forecast that helps you decide whether or not to bring an umbrella, you use your knowledge and experience to make a decision based on science," Jin says. "If you hear it's going to rain and you don't listen, you will get wet."
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Climate
| 2,020 |
September 10, 2020
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https://www.sciencedaily.com/releases/2020/09/200910130410.htm
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People are behind costly, increasing risk of wildfire to millions of homes
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People are starting almost all the wildfires that threaten U.S. homes, according to an innovative new analysis combining housing and wildfire data. Through activities like debris burning, equipment use and arson, humans were responsible for igniting 97% of home-threatening wildfires, a University of Colorado Boulder-led team reported this week in the journal
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Moreover, one million homes sat within the boundaries of wildfires in the last 24 years, the team found. That's five times previous estimates, which did not consider the damage done and threatened by small fires. Nearly 59 million more homes in the wildland-urban interface lay within a kilometer of fires."We have vastly underestimated the wildfire risk to our homes," said lead author Nathan Mietkiewicz, who led the research as a postdoc in Earth Lab, part of CIRES at the University of Colorado Boulder. "We've been living with wildfire risk that we haven't fully understood."To better understand wildfire trends in the United States, Mietkiewicz, now an analyst at the National Ecological Observatory Network, and his colleagues dug into 1.6 million government spatial records of wildfire ignition between 1992 and 2015; Earth Lab's own compilation of 120,000 incident reports; and 200 million housing records from a real estate database from Zillow.Among their findings:"Our fire problem is not going away anytime soon," said co-author Jennifer Balch, director of Earth Lab, a CIRES Fellow, and associate professor of geography. It's not just that we're building more homes in the line of fire, she said, but climate change is creating warmer, drier conditions that make communities more vulnerable to wildfire.The new study, she said, does provide guidance for policy makers. "This provides greater justification that prescribed burns, where safe, can mitigate the risk and threat of future wildfires," Balch said. And we need to construct more fireproof homes in these beautiful, but flammable landscapes, she added. "We essentially need to build better and burn better.""Smokey Bear needs to move to the suburbs," Mietkiewicz concluded. "If we can reduce the number of human-caused ignitions, we will also reduce the amount of homes threatened by wildfires."
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Climate
| 2,020 |
September 10, 2020
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https://www.sciencedaily.com/releases/2020/09/200910100612.htm
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Historical climate fluctuations in Central Europe overestimated due to tree ring analysis
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Tree rings exaggerate, a team of researchers finds. Scientists deduce historical climatic conditions for the past hundreds of years from the width of the annual growth rings of trees. Previous temperature reconstructions from the annual tree rings are however to some extent inaccurate, according to a new study. Tree rings overstate the natural climatic variations of past centuries. A comparison of data from church and city archives shows that the climate has developed much more evenly.
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"Was there a warm period in the Middle Ages that at least comes close to today's? Answers to such fundamental questions are largely sought from tree ring data," explains lead author Josef Ludescher of the Potsdam Institute for Climate Impact Research (PIK). "Our study now shows that previous climate analyses from tree ring data significantly overestimate the climate's persistence. A warm year is indeed followed by another warm rather than a cool year, but not as long and strongly as tree rings would initially suggest. If the persistence tendency is correctly taken into account, the current warming of Europe appears even more exceptional than previously assumed."To examine the quality of temperature series obtained from tree rings, Josef Ludescher and Hans Joachim Schellnhuber (PIK) as well as Armin Bunde (Justus-Liebig-University Giessen) and Ulf Büntgen (Cambridge University) focused on Central Europe. Main reason for this approach was the existing long observation series dating back to the middle of the 18th century to compare with the tree ring data. In addition, there are archives that accurately recorded the beginning of grape and grain harvests and even go back to the 14th century. These records, as well as the width of tree rings, allow temperature reconstructions. A warm summer is indicated by a wide tree ring and an early start of the harvest, a cold summer by a narrow tree ring and a late start of the harvest. The trees studied are those from altitudes where temperature has a strong influence on growth and where there is enough water for growth even in warm years."It turned out that in the tree ring data the climatic fluctuations are exaggerated. In contrast, the temperatures from the harvest records have the same persistence tendency as observation data and also the computer simulations we do with climate models," says co-author Hans Joachim Schellnhuber of PIK. "Interestingly, medieval archives thus confirm modern climate system research."To eliminate the inaccuracies of the tree ring data, the scientists used a mathematical method to adjust the strength of the persistence tendency to the harvest data and the observation data. "The adjustment does not change the chronological position of the respective cold and warm periods within the tree rings, but their intensity is reduced," explains co-author Armin Bunde from the University of Gießen. "The corrected temperature series corresponds much better with the existing observations and harvest chronicles. In its entirety the data suggests that the medieval climate fluctuations and especially the warm periods were much less pronounced than previously assumed. So the present human-made warming stands out even more."
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Climate
| 2,020 |
September 9, 2020
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https://www.sciencedaily.com/releases/2020/09/200909114739.htm
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Consequences of the 2018 summer drought
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The drought that hit central and northern Europe in summer 2018 had serious effects on crops, forests and grasslands. Researchers from the European Research Infrastructure Integrated Carbon Observation System (ICOS), including researchers from the University of Göttingen, are showing what effects this had and what lessons can be learned. The results of 16 studies that are currently underway have been published as a special issue in the journal
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The interdisciplinary teams shed light on different aspects of this research. Among many findings, they found that the plants initially benefited from the warm and sunny conditions in spring, but had too little water available for their roots when the summer heatwave started. As a result, grasslands began to dry up and numerous arable areas recorded the lowest yields for decades. The forests protected themselves by greatly reducing their evaporation for several weeks, but this then led to a sharp drop in carbon dioxide uptake. Such effects were observed simultaneously -- all the way from Switzerland to the Netherlands and Germany, and from the Czech Republic to Sweden and Finland.The Bioclimatology Group of the Faculty of Forest Sciences and Forest Ecology at the University of Göttingen contributes to ICOS with a meteorological station in the Hainich National Park. For the last 20 years every 30 minutes, the station has measured the carbon dioxide (CO2) and water vapour exchange between forest and atmosphere. Comparing the data across Europe shows that the area under investigation is one of those most affected by the 2018 drought. "In 2018, the CO2 uptake calculated over the whole year was about 30 percent lower than the average of the past 20 years," says Head of the Group Professor Alexander Knohl. "On some days in the summer of 2018, the forest actually emitted carbon dioxide instead of absorbing it," adds Dr Lukas Siebicke. "In the past 20 years, this has never happened before."The measurements from the meteorological station in the Hainich National Park are of great international scientific importance for two reasons: it is one of the world's longest time series for such continuous measurements; and it is one of the oldest unmanaged forests in which such measurements of carbon dioxide and water vapour exchange takes place.ICOS is a European research infrastructure for measuring carbon dioxide fluxes between land, ocean and atmosphere. Across Europe, 140 measuring stations in twelve countries are involved. ICOS stations are subject to a rigorous quality assurance process and provide standardised data that is made freely available for research, teaching and other applications. ICOS provides essential data for the reports of the Intergovernmental Panel on Climate Change (IPCC) and for the decision-making processes within the UN Framework Convention on Climate Change.
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Climate
| 2,020 |
September 9, 2020
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https://www.sciencedaily.com/releases/2020/09/200909100303.htm
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Do as plants do: Novel photocatalysts can perform solar-driven conversion of CO2 into fuel
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The escalating carbon dioxide (CO
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In a recent study published in They reinforced reduced titanium nanoparticles edges with dicopper oxide (CuThe development and adoption of viable methods to convert CO
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Climate
| 2,020 |
September 9, 2020
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https://www.sciencedaily.com/releases/2020/09/200909100246.htm
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Climate engineering: Modelling projections oversimplify risks
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Climate change is gaining prominence as a political and public priority. But many ambitious climate action plans foresee the use of climate engineering technologies whose risks are insufficiently understood. In a new publication, researchers from the Institute for Advanced Sustainability Studies in Potsdam, Germany, describe how evolving modelling practices are trending towards "best-case" projections. They warn that over-optimistic expectations of climate engineering may reinforce the inertia with which industry and politics have been addressing decarbonisation. In order to forestall this trend, they recommend more stakeholder input and clearer communication of the premises and limitations of model results.
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The focus of the paper lies on the models underpinning the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports -- the first port-of-call for mapping combinations of technologies, alternative pathways of deployment, and climatic impacts. The authors show how modelling of solar radiation management and carbon dioxide removal technologies tends toward "best-case" projections. According to their analysis, the poorly substantiated promises delivered by these projections influence research, policy, and industry planning in the near term and may already be entrenching carbon infrastructures. In the case of certain kinds of carbon dioxide removal, for example, the prospect of future carbon capture is sometimes wrongly seen as a substitute for present mitigation.The researchers outline ways in which this trend can be forestalled. They propose mechanisms for increasing stakeholder input and strengthening political realism in modelling. "The portrayal of modelling as explorative, technically focused mappings for supporting decision making is simplistic. Modellers have to choose parameters and design scenarios. Their choices cannot be 'neutral' -- scenarios reflect hidden judgments and create benchmarks for further conversation, whether in assessment, or in technology and policy development," says co-author Sean Low. For that reason, there needs to be more transparency about the ways in which models are constructed, perceived, and applied. Efforts to expand modelling "reality checks" with technology experts, social scientists, and a wide range of users are a pragmatic first step.The scientific community must also be wary of the selective use of projections. Projections offer schemes that are stylised, optimised, and deceptively simple. By abstracting from possible technical failures and messy politics, they can create a false sense of certainty regarding the feasibility of a particular course of action. But it would be wrong to use them as alternatives to existing climate action plans or instruction manuals. Since modelling projections can offer only partial depictions of systemic risk, it is problematic if political and industry interests co-opt a stylised version for pre-existing agendas and gloss over the models' fine print.The authors emphasise the need for policy guardrails: "In climate governance the devil really does lie in the details. The inertia of the carbon economy requires that significant efforts are made to prevent particular and short-term interests undermining policy integrity," says co-author Matthias Honegger. In addition to more transparent modelling, a lot of careful policy development and governance work is needed to ensure that solar radiation management and carbon dioxide removal technologies play a constructive role in future climate policy.
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Climate
| 2,020 |
September 9, 2020
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https://www.sciencedaily.com/releases/2020/09/200909100244.htm
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Humans, not climate, have driven rapidly rising mammal extinction rate
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Human impact can explain ninety-six percent of all mammal species extinctions of the last hundred thousand years, according to a new study published in the scientific journal
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Over the last 126,000 years, there has been a 1600-fold increase in mammal extinction rates, compared to natural levels of extinction. According to the new study, this increase is driven almost exclusively by human impact.The study further shows that even prehistoric humans already had a significant destructive impact on biodiversity -- one that was even more destructive than the largest climatic changes of Earth's recent history, such as the last ice age."We find essentially no evidence for climate-driven extinctions during the past 126,000 years Instead, we find that human impact explains 96% of all mammal extinctions during that time," asserts Daniele Silvestro, one of the researchers.This is at odds with views of some scholars, who believe that strong climatic changes were the main driving force behind most pre-historic mammal extinctions. Rather, the new findings suggest that in the past mammal species were resilient, even to extreme fluctuations in climate."However, current climate change, together with fragmented habitats, poaching, and other human-related threats pose a large risk for many species," says Daniele Silvestro.The researcher's conclusions are based on a large data set of fossils. They compiled and analyzed data of 351 mammal species that have gone extinct since the beginning of the Late Pleistocene era. Among many others, these included iconic species such as mammoths, sabre tooth tigers, and giant ground sloths. Fossil data provided by the Zoological Society of London were an important contribution to the study."These extinctions did not happen continuously and at constant pace. Instead, bursts of extinctions are detected across different continents at times when humans first reached them. More recently, the magnitude of human driven extinctions has picked up the pace again, this time on a global scale," says Tobias Andermann from the University of Gothenburg.The current extinction rate of mammals is likely the largest extinction event since the end of the dinosaur era, according to the researchers. Using computer-based simulations they predict that these rates will continue to rise rapidly -- possibly reaching up to 30,000-fold above the natural level by the year 2100. This is if current trends in human behavior and biodiversity loss continue."Despite these grim projections, the trend can still be changed. We can save hundreds if not thousands of species from extinction with more targeted and efficient conservation strategies. But in order to achieve this, we need to increase our collective awareness about the looming escalation of the biodiversity crisis, and take action in combatting this global emergency. Time is pressing. With every lost species, we irreversibly lose a unique portion of Earth's natural history," concludes Tobias Andermann.The new research is presented in a study published in this week's edition of Science Advances. The study was led by Tobias Andermann at the Gothenburg Global Biodiversity Centre and the University of Gothenburg with a team of researchers from Sweden, Switzerland, and the UK.
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Climate
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September 9, 2020
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https://www.sciencedaily.com/releases/2020/09/200909085940.htm
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Wild cousins may help crops battle climate change
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Earth is getting hotter. Huge amounts of greenhouse gases are warming the planet and altering the climate. Heat waves are harsher. Droughts are longer. And some diseases and pests are stronger than ever.
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All of that is bad news for many of Earth's inhabitants. But crops are especially vulnerable. We've bred them to depend on us, and they can succumb to many threats that are likely to get worse in the next century. All as we need more food to feed a growing population.An international group of researchers set out to test how we can help our crops adapt in the coming decades. Their idea is to use wild crop relatives.These cousins of domestic crops look like weeds and you have probably walked past them when hiking on mountain trails. You may have even seen them in the cracks of pavement in the cities. They have lived in harsh climates without any human help since the dawn of time.Scientists hope that using crop wild relatives in breeding programs can add resilience to our domestic crops while keeping them delicious."Crop wild relatives have been selected by nature over millennia to withstand the very climatic stresses that we are trying to address, and hence present a new hope," says Filippo Bassi. Bassi is a scientist in Morocco at the International Center for Agricultural Research in the Dry Areas (ICARDA).But it can be risky to change how breeders work. "Before making the final decision to shift investments from normal breeding to the use of crop wild relatives, it is critical to make sure that there is a real advantage in doing so," Bassi says.To test this idea, Bassi's international team of scientists, coming from Africa, Europe, Asia and South America, focused on durum wheat.The team gathered 60 unique varieties of wheat to expose to a battery of harsh tests. These included fungal diseases, drought and high temperatures. One-third of the wheat lines the team used were developed by combining wild relatives of wheat with strong, commercial varieties.These wild relative-derived varieties of wheat were robust compared to more conventional varieties. About a third of wild relative varieties were resistant to the fungal disease Septoria, compared to just a tenth of the others. But conventional wheat varieties were more resistant to other diseases, like leaf rust, that have been the focus of past breeding programs.Where the wild relative wheat varieties really shone was under drought and heat stress. During drought, the wild relative lines had larger grains, a critical adaptation and market trait for this crop. And, when the nutrient nitrogen was in short supply, the wild-derived lines produced a higher yield than the other wheat varieties."In the case of temperature, the crop wild relative presented a clear advantage with a yield increase of 42 percent under heat stress," says Bassi. "Yield losses to heat can be drastic, and the use of crop wild relatives to breed new varieties appears to be a very strategic approach to address this climatic challenge."But resilience isn't the whole story. We depend on crops to make food. And crops are different from their wild cousins in large part because humans have selected crops over many centuries to adapt to their needs, including a preference for making delicious foods.That is why Bassi's team also looked at the usefulness of the 60 wheat varieties for making pasta. Here, the wild-derived wheat lines were the least suitable for pasta making. "That's a disappointment," says Bassi. "But not a deal breaker.""This does not prove that the use of crop wild relatives will inevitably result in poor industrial quality," says Bassi. "But rather that it is important for breeders to be aware of this risk and develop breeding strategies that address this issue."Overall, durum wheat's wild relatives appeared useful. When crossed to elite commercial varieties, they provided increased resistance to heat, drought and some diseases. These are precisely the threats facing not just durum wheat, but most major crops in a warming world. That's good news for plant breeders -- and the public."The crop wild relatives showed great promise in terms of climate change adaptation," says Bassi. "I hope the public will be re-assured that breeders are testing all possible opportunities to prepare agriculture for climate challenges."
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September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908200535.htm
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Deep channels link ocean to Antarctic glacier
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Newly discovered deep seabed channels beneath Thwaites Glacier in West Antarctica may be the pathway for warm ocean water to melt the underside of the ice. Data from two research missions, using aircraft and ship, are helping scientists to understand the contribution this huge and remote glacier is likely to make to future global sea level rise.
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Researchers from UK and US International Thwaites Glacier Collaboration (ITGC), collected data from the glacier and adjoining Dotson and Crosson ice shelves during January-March 2019. While one team collected airborne data flying over the glacier and ice shelf in a British Antarctic Survey Twin Otter aircraft, the other mapped the sea floor at the ice front from the US Antarctic Program icebreaker RV Nathaniel B Palmer.Publishing this month (9 September) in the journal Over the past 30 years, the overall rate of ice loss from Thwaites and its neighbouring glaciers has increased more than 5-fold. Already, ice draining from Thwaites into the Amundsen Sea accounts for about four percent of global sea-level rise. A run-away collapse of the glacier could lead to a significant increase in sea levels of around 65 cm (25 inches) and scientists want to find out how quickly this could happen.Lead author Dr Tom Jordan, an aero-geophysicist at British Antarctic Survey (BAS), who led the airborne survey, says:"It was fantastic to be able to map the channels and cavity system hidden beneath the ice shelf; they are deeper than expected -- some are more than 800 metres deep. They form the critical link between the ocean and the glacier."The offshore channels, along with the adjacent cavity system, are very likely to be the route by which warm ocean water passes underneath the ice shelf up to the grounding line, where the ice meets the bed."Dave Porter at LDEO Columbia University, who flew over Thwaites Glacier for the airborne survey, says:"Flying over the recently-collapsed ice tongue and being able to see first-hand the changes occurring at Thwaites Glacier was both awe inspiring and disconcerting, but also gratifying to know the airborne data we were collecting would help reveal the hidden structures below."Exceptional sea-ice break up in early 2019 enabled the team on the RV Nathaniel B Palmer to survey over 2000 square kilometres of sea floor at the glacier's ice front. The area surveyed had previously been hidden beneath part of the floating ice shelf extending from Thwaites Glacier, which broke off in 2002, and in most subsequent years the area was inaccessible due to thick sea-ice cover. The team's findings reveal the sea floor is generally deeper and has more deep channels leading towards the grounding line under the ice shelf than was previously thought.Lead author, Dr Kelly Hogan, is a marine geophysicist at BAS. She was part of the team surveying the seabed. She says:"We found the coastal sea floor, which is incredibly rugged, is a really good analogue for the bed beneath the present-day Thwaites Glacier both in terms of its shape and rock type. By examining retreat patterns over this sea-floor terrain we will be able to help numerical modellers and glaciologists in their quest to predict future retreat."This research has filled a critical data gap. Together the new coastal sea floor maps and the cavity maps track the deep channels for over 100 km to where the glacier sits on the bed. For the first time we have a clear view of the pathways along which warm water can reach the underside of the glacier, causing it to melt and contribute to global sea-level rise."Ice shelf -- is a large floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are only found in Antarctica, Greenland, Canada, and the Russian Arctic.Ice sheet -- also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than 50,000 km2 (19,000 sq mi).Glacier -- is a huge mass of ice that moves slowly over land. The term "glacier" comes from the French word glace (glah-SAY), which means ice. Glaciers are often called "rivers of ice."
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Climate
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September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908170535.htm
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Process that might have led to first organic molecules
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New research led by the American Museum of Natural History and funded by NASA identifies a process that might have been key in producing the first organic molecules on Earth about 4 billion years ago, before the origin of life. The process, which is similar to what might have occurred in some ancient underwater hydrothermal vents, may also have relevance to the search for life elsewhere in the universe. Details of the study are published this week in the journal
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All life on Earth is built of organic molecules -- compounds made of carbon atoms bound to atoms of other elements such as hydrogen, nitrogen and oxygen. In modern life, most of these organic molecules originate from the reduction of carbon dioxide (COTo tackle this question, Museum Gerstner Scholar Victor Sojo and Reuben Hudson from the College of the Atlantic in Maine devised a novel setup based on microfluidic reactors, tiny self-contained laboratories that allow scientists to study the behavior of fluids -- and in this case, gases as well -- on the microscale. Previous versions of the reactor attempted to mix bubbles of hydrogen gas and CO"Instead of bubbling the gases within the fluids before the reaction, the main innovation of the new reactor is that the fluids are driven by the gases themselves, so there is very little chance for them to escape," Hudson said.The researchers used their design to combine hydrogen with CO"The consequences extend far beyond our own biosphere," Sojo said. "Similar hydrothermal systems might exist today elsewhere in the solar system, most noticeably in Enceladus and Europa -- moons of Saturn and Jupiter, respectively -- and so predictably in other water-rocky worlds throughout the universe.""Understanding how carbon dioxide can be reduced under mild geological conditions is important for evaluating the possibility of an origin of life on other worlds, which feeds into understanding how common or rare life may be in the universe," added Laurie Barge from NASA's Jet Propulsion Laboratory, an author on the study.The researchers turned CO"The results of this paper touch on multiple themes: from understanding the origins of metabolism, to the geochemistry that underpins the hydrogen and carbon cycles on Earth, and also to green chemistry applications, where the bio-geo-inspired work can help promote chemical reactions under mild conditions," added Shawn E. McGlynn, also an author of the study, based at the Tokyo Institute of Technology.Other authors on this study include Ruvan de Graaf and Mari Strandoo Rodin from the College of the Atlantic, Aya Ohno from the RIKEN Center for Sustainable Resource Science in Japan, Nick Lane from University College London, Yoichi M.A. Yamada from RIKEN, Ryuhei Nakamura from RIKEN and Tokyo Institute of Technology, and Dieter Braun from Ludwig-Maximilians University in Munich.This work was supported in part by NASA's Maine Space Grant Consortium (SG-19-14 and SG-20-19), the U.S. National Science Foundation (1415189 and 1724300), the Japan Society for the Promotion of Science (FY2016-PE-16047 and FY2016-PE-16721), the National Institutes of Health's National Institute of General Medical Sciences (P20GM103423), the European Molecular Biology Organization (ALTF- 725 1455-2015), the Institute for Advanced Study in Berlin, and the Gerstner Family Foundation.
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Climate
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September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908131058.htm
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Fossil growth reveals insights into the climate
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Panthasaurus maleriensis lived about 225 million years ago in what is now India. It is an ancestor of today's amphibians and has been considered the most puzzling representative of the Metoposauridae. Paleontologists from the universities of Bonn (Germany) and Opole (Poland) examined the fossil's bone tissue and compared it with other representatives of the family also dating from the Triassic. They discovered phases of slower and faster growth in the bone, which apparently depended on the climate. The results have now been published in the journal
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Temnospondyli belong to the ancestors of today's amphibians. This group of animals became extinct about 120 million years ago in the Early Cretaceous. The Temnospondyli also include the Metoposauridae, a fossil group that lived exclusively in the Late Triassic about 225 million years ago. Remains of these ancestors are present on almost every continent. In Europe, they are found mainly in Poland, Portugal and also in southern Germany.Panthasaurus maleriensis, the most puzzling representative of the Metoposauridae to date, lived in what is now India, near the town of Boyapally. "Until now, there were hardly any investigation opportunities because the fossils were very difficult to access," explains Elzbieta Teschner from the University of Opole, who is working on her doctorate in paleontology in the research group of Prof. Dr. Martin Sander at the University of Bonn. Researchers from the Universities of Bonn and Opole, together with colleagues from the Indian Statistical Institute in Kolkata (India), have now examined the tissue of fossil bones of a metoposaur from the Southern Hemisphere for the first time. The amphibian, which resembled a crocodile, could grow up to three meters in length."The investigated taxon is called Panthasaurus maleriensis and was found in the Maleri Formation in Central India," notes Teschner with regard to the name. So far, the fossil has only been examined morphologically on the basis of its external shape. "Histology as the study of tissues, on the other hand, provides us with a valuable insight into the bone interior," says Dr. Dorota Konietzko-Meier from the Institute for Geosciences at the University of Bonn. The histological findings can be used to draw conclusions about age, habitat and even climate during the animal's lifetime.The histological examinations revealed that the young animals had very rapid bone growth and that this growth decreased with age. The Indian site where the bones were found provides evidence of both young and adult animals, in contrast to Krasiejów (south-western Poland), where only young animals were found. Geological and geochemical data show that the Late Triassic consisted of alternating dry and rainy periods, as in the present monsoon climate of India. "This sequence is also reflected in the material examined," says Teschner. "There are phases of rapid growth, known as zones, and a slowdown, known as annulus." Normally, one can still observe stagnation lines in the bones, which develop during unfavorable phases of life, for example during very hot or very cold seasons.In Panthasaurus maleriensis, however, growth never comes to a complete cessation. In comparison: the Polish Metoposaurus krasiejowensis shows the same alternation of zones and annuli in one life cycle and no stagnation lines, whereas the Moroccan representative of the metoposaurs Dutuitosaurus ouazzoui shows stagnation lines -- that is, a complete stop in growth -- in each life cycle.The different growth phases in the bones allow for a comparison of climatic conditions. This means that the climate in the Late Triassic would have been milder in Central India than in Morocco, but not as mild as in the area that today belongs to Poland. Sander: "Fossil bones therefore offer a window into the prehistoric past."
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Climate
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September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908131026.htm
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Developing models to predict storm surges
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Storm surges sometimes can increase coastal sea levels 10 feet or more, jeopardizing communities and businesses along the water, but new research from the University of Central Florida shows there may be a way to predict periods when it's more likely that such events occur.
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In a study published recently in the El Niño is a periodic warming of sea surface temperatures in the Pacific Ocean between Asia and South America that can affect weather around the globe."If we were capable to predict in advance when we go through periods of relatively higher flood risk, that would be very useful information to have, for example in order to make available and deploy resources way in advance," says Mamunur Rashid, the study's lead author and a postdoctoral research associate in UCF's Department of Civil, Environmental and Construction Engineering."Our analysis was only the first step in this direction, and while we show that there is some capability in predicting storm surge variability over inter-annual to decadal time scales, we are not at the point yet where such a modeling framework can be used in an operational way or for making important decisions based on the results," he says.The study was supported by the National Oceanic and Atmospheric Administration's Climate Program Office, Climate Observations and Monitoring Program.The study builds on previous research that showed storm surge is a major factor in extreme sea level variability, which is when water level thresholds are higher or lower than normal conditions. In addition to storm surge, factors behind extreme sea level variability also include mean sea level and low frequency tides.Coastal flood risk assessments often omit the role of extreme sea level variations, ignoring that flood risk is higher in some periods than others, and instead focus on long-term sea level rise, says Thomas Wahl, study co-author and an assistant professor in UCF's Department of Civil, Environmental and Construction Engineering."Knowing how the extreme sea level variations we are investigating modulate the potential losses can help better plan and adapt to mitigate these impacts," he says.To develop the models, the researchers linked large-scale climate variability events, such as El Niño, to variability in storm surge activity. Then they tested the models by having them predict past storm surge variability and then compared their predictions with what actually occurred.The results indicated that the models matched the overall trends and variability of storm surge indicators for almost all coastal regions of the U.S during both the tropical and extra-tropical storm seasons.For Florida, the models reflect the difference in the variability of storm surge on the west coast compared to the east, Wahl says."It's a little bit larger on the west coast, and the highs and lows along the two coastlines are also not in phase," he says.The researchers say they will continue to improve their models as the global climate models they employ continue to improve in accuracy.
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Climate
| 2,020 |
September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908113331.htm
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Trees living fast die young
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A global analysis reveals for the first time that across almost all tree species, fast growing trees have shorter lifespans. This international study further calls into question predictions that greater tree growth means greater carbon storage in forests in the long term.
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Currently, forests absorb large amounts of carbon dioxide (COMost earth system models predict that this growth stimulation will continue to cause a net carbon uptake of forests this century. But, the study, led by the University of Leeds and published today in The international study is the largest to date looking at the relationship between tree growth and tree lifespan. The researchers examined more than 200 thousand tree-ring records from 82 tree species from sites across the globe.It confirms that accelerated growth results in shorter tree lifespans, and that growth-lifespan trade-offs are indeed near universal, occurring across almost all tree species and climates. This suggests that increases in forest carbon stocks may be short lived.Lead author of the study, Dr Roel Brienen from the School of Geography at Leeds, said: "While it has been known for a long time that fast-growing trees live shorter, so far this was only shown for a few species and at a few sites."We started a global analysis and were surprised to find that these trade-offs are incredibly common. It occurred in almost all species we looked at, including tropical trees."Our modelling results suggest there is likely to be a time lag before we see the worst of the potential loss of carbon stocks from increases in tree mortality. They estimate that global increases in tree death don't kick in until after sites show accelerated growth."This is consistent with observations of increased tree death trends across the globe. For example, previous Leeds research has shown long-term increases in tree mortality rates lagging behind tree growth increases in the Amazon forest."Co-author Prof Manuel Gloor, also from the School of Geography, said: "Earth system models often do not, or cannot by design, take into account this negative feedback, and model projections of the global forest carbon sink persistence are thus likely inaccurate and too optimistic. Our findings imply that a much reduced future forest carbon sink further increases the urgency to curb greenhouse emissions."The trade-off may be due to environmental variables affecting tree growth and lifespan. For example, co-author, Dr Alfredo Di Filippo from Tuscia University, Italy previously reported that lifespan of beech trees in the Northern Hemisphere decreases by roughly 30 years for each degree of warming.The current analysis confirms that, across biomes, reductions in lifespan are not due directly to temperature per se, but are a result of faster growth at warmer temperatures.Their findings suggests that a prominent cause of the widespread occurrence of a growth lifespan trade-off is that chances of dying increase dramatically as trees reach their maximum potential tree size.Nonetheless, other factors may still play a role as well. For example, trees that grow fast may invest less in defences against diseases or insect attacks, and may make wood of lower density or with water transport systems more vulnerable to drought.Study co-author Dr Steve Voelker, from the Department of Environmental and Forest Biology, Syracuse, New York, said: "Our findings, very much like the story of the tortoise and the hare, indicate that there are traits within the fastest growing trees that make them vulnerable, whereas slower growing trees have traits that allow them to persist."Our society has benefitted in recent decades from the ability of forests to increasingly store carbon and reduce the rate at which CO
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Climate
| 2,020 |
September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908113322.htm
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Climate change will decimate Palm Springs, Coachella Valley tourism
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A new UC Riverside study finds that climate change will have a devastating effect on the greater Palm Springs area's dominant industry -- tourism.
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Thousands known as "snowbirds" flock to the region annually from elsewhere in the country to escape freezing winters. However, due to climate change, the number of days above 85 degrees between November and April is projected to increase by up to 150% by the end of the century.These changes are enough to prevent many from patronizing the area's famous outdoor attractions and events such as the annual Coachella Valley Music Festival, according to the study published this week in the journal Many businesses in the Palm Springs area already close due to lack of customers during the hot summer months, when daytime high temperatures average up to 108 degrees in July and August. Employment follows these patterns, with regional employment declining by 7.2 percent between April and October in 2017.The researchers modeled two different future climate scenarios -- one in which heat-trapping gases are significantly reduced, resulting in slowed warming, and one in which emissions are not mitigated at all."The two scenarios differed a little by mid-century, but were very different by 2100," said Francesca Hopkins, assistant professor of climate change and sustainability. "In both cases we saw big declines in the number of days suitable for snowbirds, but this was much more pronounced in the scenario with no emissions reductions."In order to assess future effects of increased heat, the researchers analyzed two key components of the local tourism industry in addition to the winter weather: the number of visitors to The Living Desert Zoo and Gardens, a popular outdoor zoo, and the likelihood of extreme heat at the Coachella music festival.The Living Desert, established 50 years ago, is a nonprofit zoo visited by more than 510,000 people last year. The research team found that it stands to lose up to $1.44 million annually in tourism in today's dollars with 18 percent fewer visitors at the end of the century.Similarly, heat is also projected to impact the annual Coachella music festival, which began in 1999, and attracts roughly 250,000 concertgoers. The researchers did not assume that increased heat will necessarily affect attendance. However, they did find that probability of attendee exposure to extreme heat -- if it continues to be held in April -- could increase six-fold by end of century if climate change goes unmitigated."Though other studies have focused on the impact that climate change will have on cold winter destinations popular for sports like skiing, this is one of the first to focus on a warm winter destination, and its impact on such a specific region," Hopkins said.Places like the Coachella Valley are especially vulnerable to the impacts of climate change because they cannot shift snowbird season to cooler times of year, since those don't exist, Hopkins explained.Cindy Yañez, a UCR physics graduate and first author of the study, was born in the Coachella Valley, and has lived there most of her life. Many people in the area have jobs that require them to work outdoors, either in agriculture or tourism. She wonders whether there will be a climate breaking point that might cause locals like these to move away."Weather is a resource that draws in money just like other resources do. If that gets redistributed it could have severe impacts on peoples' lives both physically and economically," Yañez said. "I am hoping this research will start a conversation in the community. We still have time to avoid the worst of these predictions if we can reduce our greenhouse gas emissions today."
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Climate
| 2,020 |
September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908101601.htm
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Ancient hunters stayed in frozen Northern Europe rather than migrating to warmer areas, evidence from Arctic fox bones shows
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Ancient hunters stayed in the coldest part of Northern Europe rather than migrating to escape freezing winter conditions, archaeologists have found.
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Evidence from Arctic fox bones show communities living around 27,500 years ago were killing small prey in the inhospitable North European Plains during the winter months of the last Ice Age.Researchers have found no evidence of dwellings, suggesting people only stayed for a short time or lived in tents in the area excavated, Kraków Spadzista in Southern Poland -- one of the largest Upper Palaeolithic sites in Central Europe. Until now it wasn't clear if people retreated elsewhere each winter to avoid the intense cold.Dr Alexander Pryor, from the University of Exeter, who led the study, said: "Our research shows the cold harsh winter climates of the last ice age were no barrier to human activity in the area. Hunters made very specific choices about where and when to kill their prey."Inhabitants of Kraków Spadzista around 27,500 years ago killed and butchered large numbers of woolly mammoths and arctic foxes at the site. For the first time, the research team were able to reconstruct details of how the foxes were moving around in the landscape before they died, and also what time of the year they died, through analysing the internal chemistry and growth structures of their tooth enamel and roots.The analysis of teeth from four of the 29 hunted foxes show each was born and grew up in a different location, and had migrated either tens or hundreds of kilometres to the region before being killed by hunters -- by snares, deadfalls or other trapping methods -- for both their thick warm furs as well as meat and fat for food. The carcasses were brought back to the site to be skinned and butchered.Analysis of the dental cementum of at least 10 fox individuals demonstrate that the majority were killed between late winter and late spring, most likely in late winter. The foxes ranged in age, from sub-adult to very old.The study, published in the Around 2,400 arctic fox bones were found about 30m south of a huge concentration of bones from more than 100 individual woolly mammoths that dominate the site, in an area used for the production of lithic tools and the processing of smaller prey animals.The study suggests the Arctic fox colonised the area because they moved over long distances season by season, something they still do today, in order to find food.Dr Pryor said: "Arctic fox provided both food and hides to Palaeolithic hunters, with their fur coats reaching full length around the beginning of December; this winter fur usually begins shedding by early spring. They also lay down substantial stores of body fats seasonally that are greatest from late autumn throughout the winter season and do not start to become seriously depleted until early spring. Hunters most likely targeted the foxes in the late winter period -- before the onset of fur shedding and loss of critical fat supplies."The high numbers of fox remains found at the site suggests what was happening was a deliberate, organised procurement strategy rather than just simple incidental hunting."The analysis of teeth suggests hunters engaged in large-scale winter hunting of solitary Arctic foxes that were ranging widely across the landscape. The site was used as a base camp for ranging visits to maintain trapping lines and for processing hides.Krakow Spadzista was one of the most northerly sites in central Europe during the Late Gravettian when much of the northern plains region had already been abandoned. Mean annual temperature was between −1.0 °C and +4.3 °C.
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Climate
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September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908093733.htm
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A difficult year for forests, fields and meadows
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It was -- once again -- an unusually hot year: in 2018, large parts of Europe were beset by an extremely hot and dry summer. In Switzerland, too, the hot weather got people sweating -- right on the heels of a string of unusually warm months. It was -- at the time -- the third hottest summer and the fourth warmest spring since measurements began in 1864.
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Obviously, such unusual weather conditions also had an impact on ecosystems. Scientists from the group led by Nina Buchmann, Professor of Grassland Sciences, have now used extensive measurement data to show exactly how forests, fields and meadows reacted to the exceptional conditions in 2018. The researchers evaluated measurements from five sites, all of which are part of the Swiss FluxNet initiative, explains Mana Gharun, a postdoc in Buchmann's group and the study's lead author: "The five sites cover all altitude levels from 400 to 2,000 metres above sea level. This means we've taken very different ecosystems into account."At each of these sites, Buchmann's group has been taking measurements for years at very high temporal resolution of how much COTheir evaluation, which the researchers have just published in a special issue of the journal However, respiration rates for plants and soil organisms also increased at almost all the sites. This means that while these systems absorbed more COBuchmann points out that it is still too early for a final assessment: "We definitely need long-term data series before we can put these findings in their proper context." She and her group have been collecting measurement data at the abovementioned sites for many years, so she has a good foundation for such long-term studies.What made 2018 exceptional was not just the warm temperatures in spring and summer, but also the heavy precipitation during the preceding winter: when spring came, the mountains were covered by snow, which then melted very quickly due to the warm conditions. This benefited the higher-altitude ecosystems in particular. In contrast, the situation at lower altitudes was more difficult, as the ecosystems there were unable to use the excess water from winter to build up a soil moisture reservoir for the summer. Accordingly, they suffered more from the summer drought and heat."Water availability is a decisive factor in how ecosystems survive periods of heat," Buchmann says. "Thus, it is important to look beyond the actual dry period when studying a drought." Another unsettling consideration is that the new CH2018 climate change scenarios predict more rain and less snow in winter. The higher levels of precipitation expected in the winter months is therefore of limited benefit to ecosystems when the water runs off quickly, rather than being stored as snow.Forests are now in a critical situation. There are several indications of this, one of which is that not only spruce trees but also old beech trees are now showing stress symptoms in many places across the Swiss Plateau. This is probably also due to the fact that the following year, 2019, was also warmer and drier than average. "What we are seeing in the forests is a memory effect," Buchmann explains, "so it's possible that the impacts of such periods may not show up until long after the actual extreme event."How well the trees survive periods of drought and heat also depends on the depth at which they absorb water. Beech roots, for example, penetrate the soil to a depth of 50 or 60 centimetres and are therefore more likely to reach deeper moist layers. Spruce roots, on the other hand, reach a depth of only about 20 centimetres, making them more likely to be affected by droughts. "Things are going to get uncomfortable for lowland spruce in the medium term," Buchmann notes. "That's not a good forecast for forestry."What about the meadows? The two researchers have not yet found a memory effect there because meadows recover more quickly after a dry period. Nevertheless, meadows at lower altitudes produce significantly less forage in a year like 2018 -- bad news for farmers. Grassland farming is the central pillar of Swiss agriculture. If less grass grows on meadows in the future because of increasing summer droughts, this will have direct consequences for milk and meat production.
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Climate
| 2,020 |
September 7, 2020
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https://www.sciencedaily.com/releases/2020/09/200907112345.htm
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Changing what we eat could offset years of climate-warming emissions
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Plant protein foods -- like lentils, beans, and nuts -- can provide vital nutrients using a small fraction of the land required to produce meat and dairy. By shifting to these foods, much of the remaining land could support ecosystems that absorb CO
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In their study, the researchers analyzed and mapped areas where extensive production of animal-sourced food, which requires 83 percent of Earth's agricultural land, suppresses native vegetation, including forests.The study highlights places where changing what people grow and eat could free up space for ecosystems to regrow, offsetting our CO"The greatest potential for forest regrowth, and the climate benefits it entails, exists in high- and upper-middle income countries, places where scaling back on land-hungry meat and dairy would have relatively minor impacts on food security," says Matthew Hayek, the principal author of the study and an assistant professor in New York University's Department of Environmental Studies.Burning fossil fuels for energy emits COAccording to the authors' findings, vegetation regrowth could remove as much as nine to 16 years of global fossil fuel CO"We can think of shifting our eating habits toward land-friendly diets as a supplement to shifting energy, rather than a substitute," says Hayek. "Restoring native forests could buy some much-needed time for countries to transition their energy grids to renewable, fossil-free infrastructure."In their report, the authors emphasize that their findings are designed to assist locally tailored strategies for mitigating climate change. Although meat consumption in many countries today is excessive and continues to rise, raising animals remains critical in some places.These considerations will be important as countries attempt to develop their economies sustainably, according to Colorado State University's Nathan Mueller, one of the study's co-authors."Land use is all about tradeoffs," explains Mueller, an assistant professor in the Department of Ecosystem Science and Sustainability and the Department of Soil and Crop Sciences. "While the potential for restoring ecosystems is substantial, extensive animal agriculture is culturally and economically important in many regions around the world. Ultimately, our findings can help target places where restoring ecosystems and halting ongoing deforestation would have the largest carbon benefits."Recent proposals to cover much of Earth's surface in forests have generated controversy as a climate solution. Physically planting upward of a trillion trees would require a substantial physical effort. Additionally, poor planning could encourage uniform tree plantations, limit biodiversity, or deplete dwindling water in dry areas. Lastly, challenges lie in finding enough land to keep trees safe from logging or burning in the future, releasing stored carbon back into the atmosphere as COHowever, the researchers kept these potential problems in mind when devising their study."We only mapped areas where seeds could disperse naturally, growing and multiplying into dense, biodiverse forests and other ecosystems that work to remove COTechnological fixes for climate change may soon be on the horizon, like machinery that removes CO"Restoring native vegetation on large tracts of low yield agricultural land is currently our safest option for removing COBut the benefits of cutting back on meat and dairy reach far beyond addressing climate change."Reduced meat production would also be beneficial for water quality and quantity, wildlife habitat, and biodiversity," notes William Ripple, a co-author on the study and a professor of ecology at Oregon State University.Recent events have also shone a spotlight on the importance of healthy ecosystems in preventing pandemic diseases with animal origins, such as COVID-19."We now know that intact, functioning ecosystems and appropriate wildlife habitat ranges help reduce the risk of pandemics," Harwatt adds. "Our research shows that there is potential for giving large areas of land back to wildlife. Restoring native ecosystems not only helps the climate; when coupled with reduced livestock populations, restoration reduces disease transmission from wildlife to pigs, chickens, and cows, and ultimately to humans."
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September 7, 2020
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https://www.sciencedaily.com/releases/2020/09/200907112325.htm
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Multinationals' supply chains account for a fifth of global emissions
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A fifth of carbon dioxide emissions come from multinational companies' global supply chains, according to a new study led by UCL and Tianjin University that shows the scope of multinationals' influence on climate change.
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The study, published in The research shows the impact that multinationals can have by encouraging greater energy efficiency among suppliers or by choosing suppliers that are more carbon efficient.The authors proposed that emissions be assigned to countries where the investment comes from, rather than countries where the emissions are generated.Professor Dabo Guan (UCL Bartlett School of Construction & Project Management) said: "Multinational companies have enormous influence stretching far beyond national borders. If the world's leading companies exercised leadership on climate change -- for instance, by requiring energy efficiency in their supply chains -- they could have a transformative effect on global efforts to reduce emissions."However, companies' climate change policies often have little effect when it comes to big investment decisions such as where to build supply chains."Assigning emissions to the investor country means multinationals are more accountable for the emissions they generate as a result of these decisions."The study found that carbon emissions from multinationals' foreign investment fell from a peak of 22% of all emissions in 2011 to 18.7% in 2016. Researchers said this was a result of a trend of "de-globalisation," with the volume of foreign direct investment shrinking, as well as new technologies and processes making industries more carbon efficient.Mapping the global flow of investment, researchers found steady increases in investment from developed to developing countries. For instance, between 2011 and 2016 emissions generated through investment from the US to India increased by nearly half (from 48.3 million tons to 70.7 million tons), while in the same years emissions generated through investment from China to south-east Asia increased tenfold (from 0.7 million tons to 8.2 million tons).Lead author Dr Zengkai Zhang, of Tianjin University, said: "Multinationals are increasingly transferring investment from developed to developing countries. This has the effect of reducing developed countries' emissions while placing a greater emissions burden on poorer countries. At the same time it is likely to create higher emissions overall, as investment is moved to more 'carbon intense' regions."The study also examined the emissions that the world's largest companies generated through foreign investment. For instance, Total S.A.'s foreign affiliates generated more than a tenth of the total emissions of France.BP, meanwhile, generated more emissions through its foreign affiliates than the foreign-owned oil industry in any country except for the United States; Walmart, meanwhile, generated more emissions abroad than the whole of Germany's foreign-owned retail sector, while Coca-Cola's emissions around the world were equivalent to the whole of the foreign-owned food and drink industry hosted by China.
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Climate
| 2,020 |
September 7, 2020
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https://www.sciencedaily.com/releases/2020/09/200907112320.htm
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'Wrong-way' migrations stop shellfish from escaping ocean warming
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Ocean warming is paradoxically driving bottom-dwelling invertebrates -- including sea scallops, blue mussels, surfclams and quahogs that are valuable to the shellfish industry -- into warmer waters and threatening their survival, a Rutgers-led study shows.
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In a new study published in the journal The researchers studied six decades of data on 50 species of bottom-dwelling invertebrates, and found that about 80 percent have disappeared from the Georges Bank and the outer shelf between the Delmarva Peninsula and Cape Cod, including off the coast of New Jersey.Many species of fish respond to the warming ocean by migrating to cooler waters. But the "wrong-way" migrators -- which include shellfish, snails, starfish, worms and others -- share a few crucial traits. As larvae, they are weak swimmers and rely on ocean currents for transportation. As adults, they tend to remain in place, sedentary or fixed to the seafloor.The researchers found that the warming ocean have caused these creatures to spawn earlier in the spring or summer, exposing their larvae to patterns of wind and water currents they wouldn't experience during the normal spawning season. As a result, the larvae are pushed toward the southwest and inland, where waters are warmer and they are less likely to survive. The adults stay in those areas and are trapped in a feedback loop in which even warmer waters lead to even earlier spawning times and a further shrinking of their occupied areas.The researchers compared this phenomenon to "elevator-to-extinction" events in which increasing temperatures drive birds and butterflies upslope until they are eliminated from areas they once inhabited. The effect on bottom-dwelling invertebrates is more insidious, however, because these creatures could potentially thrive in cooler regions, but earlier-spring currents prevent weak-swimming larvae from reaching that refuge.The researchers noted that these effects are influenced by localized wind and current patterns. Further research is needed to determine whether the effects are similar on the U.S. Pacific coast or other ocean areas.
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Climate
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September 4, 2020
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https://www.sciencedaily.com/releases/2020/09/200904121324.htm
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Plant protein discovery could reduce need for fertilizer
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Researchers have discovered how a protein in plant roots controls the uptake of minerals and water, a finding which could improve the tolerance of agricultural crops to climate change and reduce the need for chemical fertilisers.
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The research, published in This is the first evidence showing the implications of this family in the biosynthesis of lignin, one of the most abundant organic polymers on earth. This study reveals that the molecular machinery required for Casparian strip lignin deposition is highly ordered by forming nano-domains which can have a huge impact on plant nutrition, a finding that could help in the development of crops that are efficient in taking in the nutrients they need.Food security represents a pressing global issue. Crop production must double by 2050 to keep pace with global population growth. This target is even more challenging given the impact of climate change on water availability and the drive to reduce fertilizer inputs to make agriculture become more environmentally sustainable. In both cases, developing crops with improved water and nutrient uptake efficiency would provide a solution and this.Guilhem Reyt from the School of Biosciences and Future Food Beacon at the University of Nottingham has led this research project, he says: "This research is important in revealing the molecular mechanics underpinning efforts to improve mineral nutrient and water use efficiencies and enhanced stress tolerance, making crops more able to withstand flooding, drought, nutrient deficiencies and trace element toxicities.Such improvements in agricultural and horticultural crops could also potentially benefit subsistence farmers with limited access to inorganic fertilizers which include nitrogen, phosphate and potassium and also sulphur and magnesium. This would help to reduce the cost burden such fertilizers impose and reduce the environmental and ecological damage their production and excess use causes. Improved water use efficiency and stress tolerance will also improve yields for subsistence farmers cultivating marginal lands.An improved understanding of how roots acquire important trace element and minerals should provide an important molecular mechanistic underpinning to efforts to improve food quality by helping to increase the content of essential mineral nutrients and reduce toxic trace elements in food crops."
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Climate
| 2,020 |
September 4, 2020
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https://www.sciencedaily.com/releases/2020/09/200904090312.htm
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Ocean carbon uptake widely underestimated
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The world's oceans soak up more carbon than most scientific models suggest, according to new research.
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Previous estimates of the movement of carbon (known as "flux") between the atmosphere and oceans have not accounted for temperature differences at the water's surface and a few metres below.The new study, led by the University of Exeter, includes this -- and finds significantly higher net flux of carbon into the oceans.It calculates CO"Half of the carbon dioxide we emit doesn't stay in the atmosphere but is taken up by the oceans and land vegetation 'sinks'," said Professor Andrew Watson, of Exeter's Global Systems Institute."Researchers have assembled a large database of near-surface carbon dioxide measurements -- the "Surface Ocean Carbon Atlas" ("Previous studies that have done this have, however, ignored small temperature differences between the surface of the ocean and the depth of a few metres where the measurements are made."Those differences are important because carbon dioxide solubility depends very strongly on temperature."We used satellite data to correct for these temperature differences, and when we do that it makes a big difference -- we get a substantially larger flux going into the ocean."The difference in ocean uptake we calculate amounts to about 10 per cent of global fossil fuel emissions."Dr Jamie Shutler, of the Centre for Geography and Environmental Science on Exeter's Penryn Campus in Cornwall, added: "Our revised estimate agrees much better than previously with an independent method of calculating how much carbon dioxide is being taken up by the ocean."That method makes use of a global ocean survey by research ships over decades, to calculate how the inventory of carbon in the ocean has increased."These two 'big data' estimates of the ocean sink for CO
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Climate
| 2,020 |
September 3, 2020
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https://www.sciencedaily.com/releases/2020/09/200903105605.htm
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New mathematical method shows how climate change led to fall of ancient civilization
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A Rochester Institute of Technology researcher developed a mathematical method that shows climate change likely caused the rise and fall of an ancient civilization. In an article recently featured in the journal
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Malik developed a method to study paleoclimate time series, sets of data that tell us about past climates using indirect observations. For example, by measuring the presence of a particular isotope in stalagmites from a cave in South Asia, scientists were able to develop a record of monsoon rainfall in the region for the past 5,700 years. But as Malik notes, studying paleoclimate time series poses several problems that make it challenging to analyze them with mathematical tools typically used to understand climate."Usually the data we get when analyzing paleoclimate is a short time series with noise and uncertainty in it," said Malik. "As far as mathematics and climate is concerned, the tool we use very often in understanding climate and weather is dynamical systems. But dynamical systems theory is harder to apply to paleoclimate data. This new method can find transitions in the most challenging time series, including paleoclimate, which are short, have some amount of uncertainty and have noise in them."There are several theories about why the Indus Valley Civilization declined -- including invasion by nomadic Indo-Aryans and earthquakes -- but climate change appears to be the most likely scenario. But until Malik applied his hybrid approach -- rooted in dynamical systems but also draws on methods from the fields of machine learning and information theory -- there was no mathematical proof. His analysis showed there was a major shift in monsoon patterns just before the dawn of this civilization and that the pattern reversed course right before it declined, indicating it was in fact climate change that caused the fall.Malik said he hopes the method will allow scientists to develop more automated methods of finding transitions in paleoclimate data and leads to additional important historical discoveries. The full text of the study is published in
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902182424.htm
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Gravity wave insights from internet-beaming balloons
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Giant balloons launched into the stratosphere to beam internet service to Earth have helped scientists measure tiny ripples in our upper atmosphere, uncovering patterns that could improve weather forecasts and climate models.
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The ripples, known as gravity waves or buoyancy waves, emerge when blobs of air are forced upward and then pulled down by gravity. Imagine a parcel of air that rushes over mountains, plunges toward cool valleys, shuttles across land and sea and ricochets off growing storms, bobbing up and down between layers of stable atmosphere in a great tug of war between buoyancy and gravity. A single wave can travel for thousands of miles, carrying momentum and heat along the way.Although lesser known than gravitational waves -- undulations in the fabric of space-time -- atmospheric gravity waves are ubiquitous and powerful, said Stanford University atmospheric scientist Aditi Sheshadri, senior author of a new study detailing changes in high-frequency gravity waves across seasons and latitudes. They cause some of the turbulence felt on airplanes flying in clear skies and have a strong influence on how storms play out at ground level.Published Aug. 30 in the "This was just a very lucky thing because they weren't collecting data for any scientific mission. But, incidentally, they happened to be measuring position and temperature and pressure," said Sheshadri, who is an assistant professor of Earth system science at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth).The researchers calculated gravity wave motions from data that balloons collected over 6,811 separate 48-hour periods from 2014 to 2018. "To mount an equivalent scientific campaign would be terribly expensive. With the Loon data, the analysis is messier because the data collection was incidental, but it has near-global coverage," Sheshadri said.Gravity waves are an important part of atmospheric dynamics. "They help to drive the overall circulation of the atmosphere, but some gravity waves are too small and too frequent to be observed with satellites," said the study's lead author, Erik Lindgren, who worked on the research as a postdoctoral scholar in Sheshadri's lab. "These are the gravity waves we have focused on in this study." Earlier studies using atmospheric balloons to track high-frequency gravity waves have typically incorporated data from no more than a few dozen balloon flights, covering smaller areas and fewer seasons.The Loon data proved particularly valuable for calculating high-frequency gravity waves, which can rise and fall hundreds of times in a day, over distances ranging from a few hundred feet to hundreds of miles. "They're tiny and they change on timescales of minutes. But in an integrated sense, they affect, for instance, the momentum budget of the jet stream, which is this massive planetary scale thing that interacts with storms and plays an important role in setting their course," Sheshadri said.Gravity waves also influence the polar vortex, a swirl of frigid air that usually hovers over the North Pole and can blast extreme cold into parts of Europe and the United States for months at a time. And they interact with the quasi-biennial oscillation, in which, roughly every 14 months, the belt of winds blowing high over the equator reverses direction -- with big impacts on ozone depletion and surface weather far beyond the tropics.As a result, understanding gravity waves is key to improving weather forecasts at the regional scale, especially as global warming continues to disrupt historical patterns. "Getting gravity waves right would help constrain circulation responses to climate change, like how much it's going to rain in a particular location, the number of storms -- dynamical things such as wind and rain and snow," Sheshadri said.Current climate models estimate the effects of high-frequency gravity waves on circulation in a kind of black box, with few constraints from real-world observations or application of the limited existing knowledge of the physical processes at play. "Until now, it has not been entirely clear how these waves behave in different regions or over the seasons at very high frequencies or small scales," Lindgren said.Sheshadri and colleagues focused on energy associated with high-frequency gravity waves at different time scales, and how that energy varies across seasons and latitudes. They found these waves are larger and build up more kinetic energy in the tropics and during the summer; smaller waves moving with less energy are more common close to the poles and during the winter. They also found gravity waves changing in sync with the phases of the quasi-biennial oscillation. "We uncovered distinct shifts in gravity wave activity at different times of the year and over different parts of the globe," Lindgren said. "As to exactly why is not clear."In future research, Sheshadri aims to identify which gravity wave sources are responsible for these differences, and to extrapolate gravity wave amplitudes at very high frequencies from relatively infrequent observations. She said, "Understanding how gravity waves drive circulation in the atmosphere, the interaction between these waves and the mean flow -- it's really the next frontier in understanding atmospheric dynamics."
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902182415.htm
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Many forests scorched by wildfire won't bounce back
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With flames racing across hundreds of square miles throughout Colorado and California this summer and a warming climate projected to boost wildfire activity across the West, residents can't help but wonder what our beloved forests will look like in a few decades.
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A new University of Colorado Boulder-led study offers an unprecedented glimpse, suggesting that when forests burn across the Southern Rocky Mountains, many will not grow back and will instead convert to grasslands and shrublands."We project that post-fire recovery will be less likely in the future, with large percentages of the Southern Rocky Mountains becoming unsuitable for two important tree species -- ponderosa pine and Douglas fir," said lead author Kyle Rodman, who conducted the study while a PhD student in the Department of Geography.Previous CU Boulder studies have looked at individual fire sites, including the site of the 2000 Walker Ranch fire in Boulder County, and found that forests recovered slowly or not at all. Even 15 years post-fire, as many as 80% of the plots the researchers surveyed still contained no new trees.Rodman and his team of coauthors -- including scientists from the U.S. Forest Service, Northern Arizona University, Colorado State University and the University of North Carolina Wilmington -- wanted to build on those studies, projecting the future by looking at the past.To that end, they looked at 22 burned areas encompassing 710 square miles from southern Wyoming through central and western Colorado to northern New Mexico. The team focused on ponderosa pine and Douglas fir forests, which make up about half of the forested area in the region."For those of us who live along Colorado's Front Range, these are the trees that we see, live near and recreate in on a daily basis," said Rodman.The study, published in the journal Using satellite images and on-the-ground measurements, the scientists first reconstructed what the forests looked like prior to the fire. Then, by counting juvenile trees and looking at tree rings, they assessed how well the forests were recovering. Not surprisingly, those at higher-elevations with lower temperatures, and more precipitation fared better. Those with more surviving trees nearby (which can spread their seeds via wind and water) were also more likely to rebound.Meanwhile, lower-elevation forests, like those south of Pueblo or in portions of the Front Range foothills, proved less resilient.And compared to regions that burned in the 19th and early 20th centuries, the more recent burn areas failed to bounce back."This study and others clearly show that the resilience of our forests to fire has declined significantly under warmer, drier conditions," said coauthor Tom Veblen, professor of geography at CU Boulder.The team then used statistical modeling to project what might happen in the next 80 years if montane forests of ponderosa pine and Douglas fir were to burn under different scenarios. In one scenario, humans do nothing to reduce greenhouse gas emissions, and climate change escalates unchecked. In another, considered a "moderate emissions scenario," emissions begin to decline after 2040.Currently, the team estimates that about half of its study area is suitable for post-fire "recovery." (Trees there may return to at least their lowest densities from the 1800s).By 2051, under the moderate emissions scenario, less than 18% of Douglas fir and ponderosa pine forests will likely recover if burned. Under the higher emission scenario, that number dips to 6.3% for Douglas fir and 3.5% percent for pine forests.Meanwhile, Veblen notes, the number and intensity of wildfires will continue its steady rise. The number of acres burned annually across the country has already doubled since the 1990s."The big takeaway here is that we can expect to have an increase in fire continue for the foreseeable future, and, at the same time, we are going to see much of our land convert from forest to non-forest," said Veblen.Rodman, now a postdoctoral research associate at the University of Wisconsin-Madison, hopes the database of post-fire recovery he and his team have created can help land managers better plan where to invest their resources, or not, after a fire.For instance, they may be better off planting seedlings in regions more likely to bounce back, rather than plant them in dry sites no longer suitable for their survival.He also hopes the projections spelled out in the paper give people one more reason to care about climate change."This was a hard study to write and can be a bit depressing to read, but there are some positive takeaways," he said. "If we can get a handle on some of these trends and reduce our greenhouse gas emissions, the outcomes may not look so dire. The future is not written in stone."
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902152152.htm
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Has Earth's oxygen rusted the Moon for billions of years?
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To the surprise of many planetary scientists, the oxidized iron mineral hematite has been discovered at high latitudes on the Moon, according to a study published today in
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Iron is highly reactive with oxygen -- forming reddish rust commonly seen on Earth. The lunar surface and interior, however, are virtually devoid of oxygen, so pristine metallic iron is prevalent on the Moon and highly oxidized iron has not been confirmed in samples returned from the Apollo missions. In addition, hydrogen in solar wind blasts the lunar surface, which acts in opposition to oxidation. So, the presence of highly oxidized iron-bearing minerals, such as hematite, on the Moon is an unexpected discovery."Our hypothesis is that lunar hematite is formed through oxidation of lunar surface iron by the oxygen from the Earth's upper atmosphere that has been continuously blown to the lunar surface by solar wind when the Moon is in Earth's magnetotail during the past several billion years," said Li.To make this discovery, Li, HIGP professor Paul Lucey and co-authors from NASA's Jet Propulsion Laboratory (JPL) and elsewhere analyzed the hyperspectral reflectance data acquired by the Moon Mineralogy Mapper (M3) designed by NASA JPL onboard India's Chandrayaan-1 mission.This new research was inspired by Li's previous discovery of water ice in the Moon's polar regions in 2018."When I examined the M3 data at the polar regions, I found some spectral features and patterns are different from those we see at the lower latitudes or the Apollo samples," said Li. "I was curious whether it is possible that there are water-rock reactions on the Moon. After months investigation, I figured out I was seeing the signature of hematite."The team found the locations where hematite is present are strongly correlated with water content at high latitude Li and others found previously and are more concentrated on the nearside, which always faces the Earth."More hematite on the lunar nearside suggested that it may be related to Earth," said Li. "This reminded me a discovery by the Japanese Kaguya mission that oxygen from the Earth's upper atmosphere can be blown to the lunar surface by solar wind when the Moon is in the Earth's magnetotail. So, Earth's atmospheric oxygen could be the major oxidant to produce hematite. Water and interplanetary dust impact may also have played critical roles""Interestingly, hematite is not absolutely absent from the far-side of the Moon where Earth's oxygen may have never reached, although much fewer exposures were seen," said Li. "The tiny amount of water (< ~0.1 wt.%) observed at lunar high latitudes may have been substantially involved in the hematite formation process on the lunar far-side, which has important implications for interpreting the observed hematite on some water poor S-type asteroids.""This discovery will reshape our knowledge about the Moon's polar regions," said Li. "Earth may have played an important role on the evolution of the Moon's surface."The research team hopes the NASA's ARTEMIS missions can return hematite samples from the polar regions. The chemical signatures of those samples can confirm their hypothesis whether the lunar hematite is oxidized by Earth's oxygen and may help reveal the evolution of the Earth's atmosphere in the past billions of years.
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902152143.htm
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Bering Sea ice extent is at most reduced state in last 5,500 years
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Through the analysis of vegetation from a Bering Sea island, researchers have determined that the extent of sea ice in the region is lower than it's been for thousands of years.
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A newly published paper in the journal "It's a small island in the middle of the Bering Sea, and it's essentially been recording what's happening in the ocean and atmosphere around it," said lead author Miriam Jones, a research geologist with the U.S. Geological Survey. Jones worked as a faculty researcher at the University of Alaska Fairbanks when the project began in 2012.The ancient sea ice record comes in the form of changes in the relative amounts of two isotopes of the element oxygen -- oxygen-16 and oxygen-18. The ratio of those two isotopes changes depending on patterns in the atmosphere and ocean, reflecting the different signatures that precipitation has around the globe. More oxygen-18 makes for an isotopically "heavier" precipitation, more oxygen-16 makes precipitation "lighter."By analyzing data from a model that tracks atmospheric movement using the isotopic signature of precipitation, the authors found that heavier precipitation originated from the North Pacific, while lighter precipitation originated from the Arctic.A "heavy" ratio signals a seasonal pattern that causes the amount of sea ice to decrease. A "light" ratio indicates a season with more sea ice. That connection has been confirmed though sea ice satellite data collected since 1979, and to a smaller extent, through the presence of some microorganisms in previous core samples.UAF's Alaska Stable Isotope Facility analyzed isotope ratios throughout the peat layers, providing a time stamp for ice conditions that existed through the millennia.After reviewing the isotopic history, researchers determined that modern ice conditions are at remarkably low levels."What we've seen most recently is unprecedented in the last 5,500 years," said Matthew Wooller, director of the Alaska Stable Isotope Facility and a contributor to the paper. "We haven't seen anything like this in terms of sea ice in the Bering Sea."Jones said the long-term findings also affirm that reductions in Bering Sea ice are due to more than recent higher temperatures associated with global warming. Atmospheric and ocean currents, which are also affected by climate change, play a larger role in the presence of sea ice."There's a lot more going on than simply warming temperatures," Jones said. "We're seeing a shift in circulation patterns both in the ocean and the atmosphere."
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902114441.htm
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Globalization is reweaving the web of life
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As introduced species spread around the world, the complex networks of interactions between plants and animals within ecosystems are becoming increasingly similar, a process likely to reinforce globalization's imprint on nature and increase risks of sweeping ecological disruption.
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Researchers at the University of Maryland's National Socio-Environmental Synthesis Center (SESYNC) and at the Center for Biodiversity Dynamics in a Changing World (BIOCHANGE) at Aarhus University, have found that introduced species are reshaping mutualistic relationships between plants and animals at an accelerating pace, creating new ecological links between previously disconnected ecosystems. Their new study is featured on the cover of the Sept. 3 issue of Featured on the cover of the Sept. 3 issue of Biodiversity is changing worldwide not only through the loss of species, but by species composition becoming more similar across different regions -- a process called biotic homogenization. Just as diversification in an investment portfolio buffers it from downturns in certain sectors, diversity across ecosystems buffers natural systems from widespread collapse. The researchers found that homogenization affects mutualistic networks made up of plants and the animals that disperse their seeds. By compiling data from hundreds of sites around the world, they found that interactions involving a plant or animal that was an introduced species has increased seven-fold over the past 75 years. The resulting loss of the portfolio effect poses greater risk of sweeping disruption by broad-scale stressors such as climate change or disease outbreaks.Introduced species are also influencing the structure of mutualistic networks in ways that reduce stability of individual ecosystems. When researchers look at the web of species interactions within natural ecosystems, there are often 'compartments' of closely interacting species that interact little outside their compartment. "This makes a network resilient because a disturbance such as overhunting, disease, or a pesticide that affects a certain species does not spread to affect species in other compartments," explained study author Evan Fricke, of SESYNC. The study shows that introduced species are often so generalized that they interact across multiple compartments, causing the loss of compartmentalized network structure and exposing more species to a given disruption.The research also shows how regions that naturally had different combinations of species and interactions because of historic geographic isolation now are linked. "Eurasian blackbirds dispersing hawthorn seeds is a common mutualistic interaction among species native to Europe," Fricke said. "Today, that same species interaction also occurs on the opposite side of the planet in New Zealand where those species have been introduced by people."The researchers quantified how introduced species have altered geographic patterns in the global web of mutualistic interactions. "What's striking to see is that natural biogeographic patterns that have existed for millions of years are being erased so quickly," Fricke said. A consequence of these new connections is that co-evolved relationships unique to isolated places in Madagascar, Hawaii, or New Zealand are now affected by introduced species. The loss of isolation changes the co-evolutionary trajectories of these mutualisms, which may cause species to evolve traits more similar to species in other parts of the world. "However, the introduced species may with time also themselves diverge from their source populations, adapting to their new setting," added study author Jens-Christian Svenning, professor and director of BIOCHANGE.As mutually beneficial interactions, seed dispersal mutualisms can determine which species are successful as ecosystems change over time. Compared to native species, introduced species are twice as likely to interact with partners that are also introduced, according to the study. This feedback may favor regeneration of introduced plants over native species. "These could have knock-on homogenizing effects for plant communities during natural reforestation of degraded forests, as well as plant range shifts as a result of climate change," Fricke said."While many unintentionally introduced species may cause homogenizing effects that threaten ecosystem integrity, other introduced species may provide ecological benefits or even reverse the effects of biotic homogenization," Svenning continued. In the Hawaiian Islands, introduced animals perform nearly all seed dispersal for native plants after numerous extinctions and severe declines in native bird populations. While Hawaii represents an extreme case, ecosystems around the world have experienced steep declines of their largest animals, many of which are important seed dispersers. Like the birds in Hawaii, introduced large mammals can perform functions missing due to the decline of native species. "Our future research will target which species interact in ways that are likely to further homogenize ecosystems and those that can reverse homogenization by filling ecological roles lost due to past species decline," Svenning concluded.
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902095142.htm
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Great Barrier Reef 'glue' at risk from ocean acidification
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The scaffolds that help hold together the world's tropical reefs are at risk from acidification due to increased carbon dioxide in the world's oceans, according to geoscientists at the University of Sydney.
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Extensive sampling of the Great Barrier Reef fossil record has shown that the calcified scaffolds that help stabilise and bind its structure become thin and weaker as pH levels fall.Scientists have seen incidental evidence for this in the past, but a new study led by Zsanett Szilagyi of the Geocoastal Research Group at the University of Sydney has shown that this is a global process, affecting reefs worldwide.The research is published this week in"For the first time we have comprehensively shown that the thickness of this geologic 'reef glue' correlates with changes in ocean pH and dissolved carbon dioxide," said Ms Szilagyi.The thickness of these crusts can now be regarded as a reliable indicator of ocean acidification going back tens if not hundreds of thousands of years."We haven't had such a complete and high-resolution record before. And this geologic study shows that as oceans became more acidic, this is reflected in the thickness of these reef crusts," said Associate Professor Jody Webster from the School of Geosciences, who coordinated the study.The 'reef glue' is made up of calcified deposits from microbes that live within reef formations around the world. Known as microbialites, these structures play an important role in many types of aquatic systems and are probably best known from the ancient stromatolites that are built by cyanobacteria in Western Australia, which are billions of years old.In some types of reef systems, including the Great Barrier Reef, microbialite crusts likely formed by sulfate-reducing bacteria stabilise and bind the reef framework, forming a robust scaffold that can be used by corals and other reef builders to colonise and grow.In the past these crusts have been more abundant than the corals and algae that grow on and around them and they display variations in thickness over time, while still performing their structural role."This means they are really good indicators of changes in environmental conditions of our oceans," Associate Professor Webster said.The study found a variation in thickness from 11.5 centimetres 22,500 years ago to about 3 centimetres in younger Great Barrier Reef sections, about 12,000 years ago.When combined with studies from 17 reef systems worldwide, the data shows this thinning of the microbialite crusts coincides with pH dropping below 8.2 right up to modern times.The researchers gathered a dataset of microbial crusts from the Great Barrier Reef as far back as 30,000 years. They compared a comprehensive three-dimensional analysis of samples to two-dimensional scans of the crust thickness.The results from the Great Barrier Reef show that the two-dimensional analysis of crust thickness provides an accurate proxy for the more detailed three-dimensional method. Compiling 2D sample data from across the world, the scientific team built a global model of microbialite thickness through time.The study found that the 2D technique gave results within 10 percent of the 3D analysis."A real breakthrough here is that we are confident we can now apply a 2D analysis to reefs and obtain reliable information about the history of microbialite formations. This will give us substantial savings in time and resources," Associate Professor Webster said."Previous studies have given us glimpses as to how these microbial crusts respond to changes in their environment. What is new in our study is that we measured more than 700 well-dated microbialite samples from the International Ocean Discovery Program on the Great Barrier Reef and combined this with a meta-analysis of 17 other reef records from around the world," he said."This allowed us to assess global-scale changes in microbialite development over the past 30,000 years. And, frankly, the findings are a stark warning sign for the dangers of rapid acidification of oceans."The study argues that in the present-day context of rapid global climate change, changes in dissolved carbon dioxide, pH and temperature, could lead to reduced microbial crust formation, thereby weakening reef frameworks in the future.
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902095132.htm
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Biodiversity: In a mite-y bit of trouble
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Mite extinctions are occurring at least 1,000 times the 'natural' rate -- a finding a University of Queensland researcher says is another warning that global biodiversity is in deep trouble.
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The 1.25 million mite species around the planet occupy an enormous variety of terrestrial and freshwater ecosystems, from the equator, to polar regions and high altitude areas.In the first global study on mite biodiversity, UQ's Dr Greg Sullivan and colleague Dr Sebahat K. Ozman-Sullivan compiled data that showed the ongoing extinction of an alarming number of species."Mites are critical to ecosystems all over the planet -- some provide essential ecosystem services such as the incorporation of organic matter into the soil," Dr Sullivan said."These services underpin the survival of innumerable species, and act as a proxy for environmental health."However, the humble mite is in trouble, as the majority of mite species are assumed to be in the tropical rainforests, where 50 per cent have been destroyed or severely degraded," he said."And based on estimates of overall biodiversity loss, around 15 per cent of mite species were likely to have become extinct by 2000."Losses are currently expected to increase by between 0.6 per cent and six per cent by 2060."The researchers said humans are responsible for the erosion of mite diversity."Habitat destruction and degradation continue on an enormous scale, with increasing global population and resource consumption the overarching drivers of extinction," Dr Sullivan said."The maintenance of mite biodiversity is highly dependent on the maintenance of plant diversity, habitat complexity and insect diversity."This means we urgently need to minimise the rate of destruction and degradation of habitat, especially in subtropical and tropical regions, and protect representative natural areas, especially the global biodiversity hotspots, like the Forests of East Australia biodiversity hotspot."In addition, he said climate change was likely worsening the effects of the other drivers at an increasing rate."We need a rapid global implementation of technologies that decrease greenhouse gas emissions and increase carbon sequestration, including the widespread regeneration of degraded forests with local species."This, coupled with an effectively executed international climate agreement, will play a critical role in determining the fate of a substantial proportion of the remaining global biodiversity -- including the small, but mighty, mite."
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902082358.htm
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Common species mirror rare animals' response to global change
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The populations of common animals are just as likely to rise or fall in number in a time of accelerating global change as those of rare species, a study suggests.
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A study of more than 2,000 species reveals animal populations around the world -- from the very common to endangered species -- are going up and down as global change alters land, sea and freshwater ecosystems.The findings highlight a need to look beyond only rare species in order to improve efforts to conserve global biodiversity, scientists say.Critically endangered animals -- such as the Hawksbill sea turtle -- were previously thought to be at greater risk of decline than common species like red deer, but the study found a wide spectrum of changes in animal numbers.Findings from the new study suggest the numbers within very common animal species are, in fact, as likely to increase or decrease as rare ones.However, species with smaller population sizes were shown to be more likely to change from year to year, potentially increasing their extinction risk in the long term.Until recently, scientists were still compiling data on how animal populations were shifting over time on a global scale across the different regions of the planet.Making use of the newly available data, a team of University of Edinburgh researchers studied nearly 10,000 animal populations recorded in the Living Planet Database between 1970 and 2014 to provide a new perspective on animal population change. These include records of mammals, reptiles, sharks, fish, birds and amphibians.The team found that 15 per cent of all populations declined during the period, while 18 per cent increased and 67 per cent showed no significant change.Amphibians were the only group in which population sizes declined, while birds, mammals and reptiles experienced increases.The overall decline in amphibians makes them a priority for conservation efforts, researchers say, as their loss could have knock-on effects in food chains and wider ecosystems.The study, published in the journal Gergana Daskalova, of the University of Edinburgh's School of GeoSciences, who led the study, said: "We often assume that declines in animal numbers are prevalent everywhere. But we found that there are also many species which have increased over the last half of a century, such as those that do well in human-modified landscapes or those that are the focus of conservation actions."Dr Isla Myers-Smith, also of the School of GeoSciences, who co-authored the study, said: "Only as we bring together data from around the world, can we begin to really understand how global change is influencing the biodiversity of our planet. The original idea for this study stemmed from a fourth year undergraduate class at the University of Edinburgh. It is so inspiring to see early career researchers tackle some of the big conservation questions of our time using advanced data science skills."
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902082347.htm
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Climate change could increase rice yields
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Rice is the most consumed staple food in the world. It is especially common in Asia, where hunger concerns are prevalent.
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Rice is classified as an annual plant, which means it completes its life cycle within one growing season then dies. However, in some tropical areas, rice can continue to grow year after year when taken care of properly.Just as grass grows back in a lawn after it is mowed, rice can be cut after it is harvested, and the plant will regrow. The farming practice of cutting the rice above ground and allowing it to regrow is called ratooning.Although Rice ratooning allows farmers to harvest more rice from the same fields, it requires a longer growing season compared to traditional single-harvest rice farming.In many areas of the world where rice is grown, a long growing season isn't a problem due to the tropical climates. But in Japan, cooler weather means rice ratooning has been a rare farming practice.Hiroshi Nakano and a research team set out to learn more about the potential of ratooning to help Japanese rice farmers. Nakano is a researcher at the National Agriculture and Food Research Organization.Average temperatures in Japan have been higher in recent years. As climate change continues to affect the region, rice farmers may have a longer window for growing rice. "Rice seedlings will be able to be transplanted earlier in the spring, and farmers can harvest rice later into the year," explains Nakano."The goal of our research is to determine the effects of harvest time and cutting height of the first harvest on the yield of the first and second rice crops," says Nakano. "Ultimately, we want to propose new farming strategies to increase yield as farmers in southwestern Japan adjust to climate change."During the study on rice ratooning, researchers compared two harvest times and two cutting heights of the first crop. After the first harvest, they collected the seeds from the cut off portions of the rice plants. Researchers measured the yield by counting and weighing the seeds. The second harvest of rice was done by hand and the yield was determined in the same way.The total grain yield and the yields from the first and second crops were different depending on the harvest times and cutting heights. This wasn't too surprising, since the team already knew harvest time and height affected yield.Rice plants harvested at the normal time for the first crop yielded more seed than the rice plants harvested earlier. "That's because the plants had more time to fill their spikelets with seed," explains Nakano."At both harvest times, rice harvested at the high cutting height had a higher yield than the low cutting height," says Nakano. That's because the plants cut at a higher height had access to more energy and nutrients stored in their leaves and stems."Our results suggest that combining the normal harvest time with the high cutting height is important for increasing yield in rice ratooning in southwestern Japan and similar climate regions," says Nakano. "This technology will likely increase rice grain yield in new environments that arise through global climate change."
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Climate
| 2,020 |
September 2, 2020
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https://www.sciencedaily.com/releases/2020/09/200902082345.htm
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Viruses could be harder to kill after adapting to warm environments
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Enteroviruses and other pathogenic viruses that make their way into surface waters can be inactivated by heat, sunshine and other microbes, thereby reducing their ability to spread disease. But researchers report in ACS'
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Enteroviruses can cause infections as benign as a cold or as dangerous as polio. Found in feces, they are released into the environment from sewage and other sources. Their subsequent survival depends on their ability to withstand the environmental conditions they encounter. Because globalization and climate change are expected to alter those conditions, Anna Carratalà, Tamar Kohn and colleagues wanted to find out how viruses might adapt to such shifts and how this would affect their disinfection resistance.The team created four different populations of a human enterovirus by incubating samples in lake water in flasks at 50 F or 86 F, with or without simulated sunlight. The researchers then exposed the viruses to heat, simulated sunlight or microbial "grazing" and found that warm-water-adapted viruses were more resistant to heat inactivation than cold-water-adapted ones. Little or no difference was observed among the four strains in terms of their inactivation when exposed to either more simulated sunlight or other microbes. When transplanted to cool water, warm-water-adapted viruses also remained active longer than the cool-water strains. In addition, they withstood chlorine exposure better. In sum, adaptation to warm conditions decreased viral susceptibility to inactivation, so viruses in the tropics or in regions affected by global warming could become tougher to eliminate by chlorination or heating, the researchers say. They also say that this greater hardiness could increase the length of time heat-adapted viruses would be infectious enough to sicken someone who comes in contact with contaminated water.
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Climate
| 2,020 |
September 1, 2020
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https://www.sciencedaily.com/releases/2020/09/200901175409.htm
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Can sunlight convert emissions into useful materials?
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Shaama Sharada calls carbon dioxide -- the worst offender of global warming -- a very stable, "very happy molecule."
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She aims to change that.Recently published in the Typically, this process requires a tremendous amount of energy. However, in the first computational study of its kind, Sharada and her team enlisted a more sustainable ally: the sun.Specifically, they demonstrated that ultraviolet (UV) light could be very effective in exciting an organic molecule, oligophenylene. Upon exposure to UV, oligophenylene becomes a negatively charged "anion," readily transferring electrons to the nearest molecule, such as CO"COThe rapidly growing concentration of carbon dioxide in the earth's atmosphere is one of the most urgent issues humanity must address to avoid a climate catastrophe.Since the start of the industrial age, humans have increased atmospheric COThe research team from the Mork Family Department of Chemical Engineering and Materials Science was led by third year Ph.D. student Kareesa Kron, supervised by Sharada, a WISE Gabilan Assistant Professor. The work was co-authored by Samantha J. Gomez from Francisco Bravo Medical Magnet High School, who has been part of the USC Young Researchers Program, allowing high school students from underrepresented areas to take part in STEM research.Many research teams are looking at methods to convert COThe process traditionally uses either heat or electricity along with a catalyst to speed up CO"Most other ways to do this involve using metal-based chemicals, and those metals are rare earth metals," said Sharada. "They can be expensive, they are hard to find and they can potentially be toxic."Sharada said the alternative is to use carbon-based organic catalysts for carrying out this light-assisted conversion. However, this method presents challenges of its own, which the research team aims to address. The team uses quantum chemistry simulations to understand how electrons move between the catalyst and COSharada said the work was the first computational study of its kind, in that researchers had not previously examined the underlying mechanism of moving an electron from an organic molecule like oligophenylene to CODespite the challenges, Sharada is excited about the opportunities for her team."One of those challenges is that, yes, they can harness radiation, but very little of it is in the visible region, where you can shine light on it in order for the reaction to occur," said Sharada. "Typically, you need a UV lamp to make it happen."Sharada said that the team is now exploring catalyst design strategies that not only lead to high reaction rates but also allow for the molecule to be excited by visible light, using both quantum chemistry and genetic algorithms.Gomez was a senior at the Bravo Medical Magnet school at the time she took part in the USC Young Researchers Program over the summer, working in Sharada's lab. She was directly mentored and trained in theory and simulations by Kron. Sharada said Gomez's contributions were so impressive that the team agreed she deserved an authorship on the paper.Gomez said that she enjoyed the opportunity to work on important research contributing to environmental sustainability. She said her role involved conducting computational research, calculating which structures were able to significantly reduce CO"Traditionally we are shown that research comes from labs where you have to wear lab coats and work with hazardous chemicals," Gomez said. "I enjoyed that every day I was always learning new things about research that I didn't know could be done simply through computer programs.""The first-hand experience that I gained was simply the best that I could've asked for, since it allowed me to explore my interest in the chemical engineering field and see how there are many ways that life-saving research can be achieved," Gomez said.
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Climate
| 2,020 |
August 31, 2020
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https://www.sciencedaily.com/releases/2020/08/200831165715.htm
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Scientists unlock crops' power to resist floods
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Enzymes that control a plant's response to lower oxygen levels could be manipulated to make vital crops resistant to the impacts of flooding triggered by climate change, new research shows.
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Co-author Dr Mark White in the School of Chemistry at the University of Sydney said: "Climate change is a major global issue, not least for its impact on food security. We hope these findings can help produce flood-tolerant crops to help mitigate the devasting social and economic impact of extreme weather events on food production."The research, largely done at the University of Oxford, is published today in the Climate change has increased the number and intensity of global flooding events, threatening food security through significant crop loss. Plants, including staple crops such as rice, wheat and barley, can survive temporary periods of flooding by activating energy pathways that don't rely on air in response to the low oxygen conditions in water.These responses are controlled by oxygen-sensing enzymes called the Plant Cysteine Oxidases (PCOs), which use oxygen to regulate the stability of proteins that control gene activity.The research describes the molecular structures of the PCOs for the first time, identifying chemical features that are required for enzyme activity."The results provide a platform for future efforts to manipulate the enzyme function in an attempt to create flood-resistant crops that can mitigate the impact of extreme weather events," Dr White said.
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Climate
| 2,020 |
August 31, 2020
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https://www.sciencedaily.com/releases/2020/08/200831112354.htm
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Warmer, acidifying ocean brings extinction for reef-building corals, renewal for relatives
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Changes in ocean chemistry and temperature have had a dramatic effect on the diversity of corals and sea anemones, according to a team of scientists who have traced their evolution through deep time. A new study, published Aug. 31 in the journal
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New genetic analyses show that corals, which together with sea anemones make up a class of animals known as anthozoans, have been on the planet for 770 million years. That is 250 million years before the earliest undisputed fossil evidence of their existence -- and long enough to experience massive shifts in climate, fluctuations in ocean chemistry and several mass extinctions.In the new study, a research team led by scientists from Harvey Mudd College, the American Museum of Natural History and the Smithsonian's National Museum of Natural History examined how these past conditions affected anthozoan diversity. That was possible thanks to a new molecular approach developed by Andrea Quattrini, research zoologist and curator of corals at the National Museum of Natural History, Catherine McFadden, a biologist at Harvey Mudd College, and Estefanía Rodríguez, a curator at the American Museum of Natural History, which allowed the team to compare nearly 2,000 key regions of anthozoan genomes to discern the evolutionary relationships between species. The team analyzed hundreds of anthozoan specimens that were collected from around the world and are now stored in museum collections. When this molecular data was aligned with fossil evidence of anthozoan history, it revealed how these diverse animals evolved over geologic time.Over the Earth's history, changes in acidity and ion concentrations have shifted the ocean's chemical composition between two states, known as aragonite and calcite seas. These changes, as well as changes in ocean water temperature, appear to have played an important role in determining what kinds of skeletons corals were able to produce and, thus, how anthozoans evolved.Stony corals -- the type that build massive reefs that support complex marine ecosystems -- take up minerals from the water to construct hard skeletons from a form of calcium carbonate known as aragonite. Other corals, such as sea fans and black corals, build their softer skeletons from protein or calcite (a less soluble form of calcium carbonate), whereas sea anemones have no skeleton at all.Working with an international team of researchers, including Gabriela Farfan, the National Museum of Natural History's Coralyn W. Whitney Curator of Gems and Minerals, Quattrini and colleagues found that stony corals did not arise until conditions favored the construction of their aragonite skeletons -- periods of aragonite seas, when ocean temperatures were relatively cool. During periods of calcite seas, when carbon dioxide is more abundant in the atmosphere and oceans are more acidic, evolution favored anemones and corals that built their skeletons from protein or calcite.Notably, it was these other anthozoans that fared best after reef crises -- times when up to 90% of reef-building organisms died off as oceans warmed and became more acidic. "Our study showed that after these reef crises, we actually get an increased diversification of anthozoans in general, particularly those that can do well under these climate conditions -- ones that aren't producing aragonite and aren't making big reefs," Quattrini said.That is consistent with observations from today's reefs, which are threatened by climate change and other human activities. "Current ecological studies have shown that when stony corals die off, these other anthozoans start to colonize dead coral and prosper," Quattrini said. "We actually see that in our evolutionary tree, too.""Unfortunately, although these softer-bodied species may adapt better to climate change than stony corals, they don't form large reefs," McFadden said. "So, in the future, reefs may be replaced by different marine communities. This already appears to be happening in the Caribbean where stony corals are being replaced by 'forests' of sea fans."Today, about 1,300 species of stony coral inhabit the ocean, favored by aragonite sea conditions. But rising levels of carbon dioxide in the atmosphere are warming and acidifying the waters, making them less hospitable for these and other organisms whose shells and skeletons are made from aragonite. "Aragonite is expected to dissolve under ocean acidification," Quattrini said. "As our seas are becoming more acidic and warmer, it's likely that the skeletons of corals will dissolve or not be able to grow."The new study suggests that as the climate changes, these ecosystems may also see increased diversification of anthozoans without aragonite skeletons. Nevertheless, loss of reef-building corals will have devastating consequences for communities who depend on reefs and the rich, complex ecosystems they support for fishing, shoreline protection and tourism. "Corals have suffered extinctions in the past when climate has posed challenges, and we'll likely see that in the future," Quattrini said. "The best way to protect them is to curb our carbon emissions.""This study shows us how nature through evolution is able to adapt, survive and reinvent itself, so when hard corals are not able to survive, their soft-bodied relatives such as sea anemones will thrive instead," Rodríguez said. "The question is whether we will be able to adapt and reinvent ourselves once nature, as we currently know it, is not there anymore."Funding for this research was provided by the National Science Foundation.
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Climate
| 2,020 |
August 31, 2020
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https://www.sciencedaily.com/releases/2020/08/200831112101.htm
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Sea level rise from ice sheets track worst-case climate change scenario
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Ice sheets in Greenland and Antarctica whose melting rates are rapidly increasing have raised the global sea level by 1.8cm since the 1990s, and are matching the Intergovernmental Panel on Climate Change's worst-case climate warming scenarios.
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According to a new study from the University of Leeds and the Danish Meteorological Institute, if these rates continue, the ice sheets are expected to raise sea levels by a further 17cm and expose an additional 16 million people to annual coastal flooding by the end of the century.Since the ice sheets were first monitored by satellite in the 1990s, melting from Antarctica has pushed global sea levels up by 7.2mm, while Greenland has contributed 10.6mm. And the latest measurements show that the world's oceans are now rising by 4mm each year."Although we anticipated the ice sheets would lose increasing amounts of ice in response to the warming of the oceans and atmosphere, the rate at which they are melting has accelerated faster than we could have imagined," said Dr Tom Slater, lead author of the study and climate researcher at the Centre for Polar Observation and Modelling at the University of Leeds."The melting is overtaking the climate models we use to guide us, and we are in danger of being unprepared for the risks posed by sea level rise."The results are published today in a study in the journal Dr Anna Hogg, study co-author and climate researcher in the School of Earth and Environment at Leeds, said: "If ice sheet losses continue to track our worst-case climate warming scenarios we should expect an additional 17cm of sea level rise from the ice sheets alone. That's enough to double the frequency of storm-surge flooding in many of the world's largest coastal cities."So far, global sea levels have increased in the most part through a mechanism called thermal expansion, which means that volume of seawater expands as it gets warmer. But in the last five years, ice melt from the ice sheets and mountain glaciers has overtaken global warming as the main cause of rising sea levels.Dr Ruth Mottram, study co-author and climate researcher at the Danish Meteorological Institute, said: "It is not only Antarctica and Greenland that are causing the water to rise. In recent years, thousands of smaller glaciers have begun to melt or disappear altogether, as we saw with the glacier Ok in Iceland, which was declared "dead" in 2014. This means that melting of ice has now taken over as the main contributor of sea level rise. "
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Climate
| 2,020 |
August 28, 2020
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https://www.sciencedaily.com/releases/2020/08/200828204944.htm
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Natural disasters must be unusual or deadly to prompt local climate policy change
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Natural disasters alone are not enough to motivate local communities to engage in climate change mitigation or adaptation, a new study from Oregon State University found.
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Rather, policy change in response to extreme weather events appears to depend on a combination of factors, including fatalities, sustained media coverage, the unusualness of the event and the political makeup of the community.Climate scientists predict that the frequency and severity of extreme weather events will only continue to increase in coming decades. OSU researchers wanted to understand how local communities are reacting."There's obviously national and state-level climate change policy, but we're really interested in what goes on at the local level to adapt to these changes," said lead author Leanne Giordono, a post-doctoral researcher in OSU's College of Public Health and Human Sciences. "Local communities are typically the first to respond to extreme events and disasters. How are they making themselves more resilient -- for example, how are they adapting to more frequent flooding or intense heat?"For the study, which was funded by the National Science Foundation, Giordono and co-authors Hilary Boudet of OSU's College of Liberal Arts and Alexander Gard-Murray at Harvard University examined 15 extreme weather events that occurred around the U.S. between March 2012 and June 2017, and any subsequent local climate policy change.These events included flooding, winter weather, extreme heat, tornadoes, wildfires and a landslide.The study, published recently in the journal "For both recipes, experiencing a high-impact event -- one with many deaths or a presidential disaster declaration -- is a necessary condition for future-oriented policy adoption," Giordono said.In addition to a high death toll, the first recipe consisted of Democrat-leaning communities where there was focused media coverage of the weather event. These communities moved forward with adopting policies aimed at adapting in response to future climate change, such as building emergency preparedness and risk management capacity.The second recipe consisted of Republican-leaning communities with past experiences of other uncommon weather events. In these locales, residents often didn't engage directly in conversation about climate change but still worked on policies meant to prepare their communities for future disasters.In both recipes, policy changes were fairly modest and reactive, such as building fire breaks, levees or community tornado shelters. Giordono referred to these as "instrumental" policy changes."As opposed to being driven by ideology or a shift in thought process, it's more a means to an end," she said. "'We don't want anyone else to die from tornadoes, so we build a shelter.' It's not typically a systemic response to global climate change."In their sample, the researchers didn't find any evidence of mitigation-focused policy response, such as communities passing laws to limit carbon emissions or require a shift to solar power. And some communities did not make any policy changes at all in the wake of extreme weather.The researchers suggest that in communities that are ideologically resistant to talking about climate change, it may be more effective to frame these policy conversations in other ways, such as people's commitment to their community or the community's long-term viability.Without specifically examining communities that have not experienced extreme weather events, the researchers cannot speak to the status of their policy change, but Giordono said it is a question for future study."In some ways, it's not surprising that you see communities that have these really devastating events responding to them," Giordono said. "What about the vast majority of communities that don't experience a high-impact event -- is there a way to also spark interest in those communities?""We don't want people to have to experience these types of disasters to make changes."
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Climate
| 2,020 |
August 28, 2020
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https://www.sciencedaily.com/releases/2020/08/200828140308.htm
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Fossil trees on Peru's Central Andean Plateau tell a tale of dramatic environmental change
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As the Earth's surface transforms, entire ecosystems come and go. The anatomy of fossil plants growing in the Andean Altiplano region 10 million years ago calls current paleoclimate models into question, suggesting that the area was more humid than models predict.
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On an expedition to the Central Andean Plateau, researchers from the Smithsonian Tropical Research Institute (STRI) and colleagues were astounded to find a huge fossil-tree buried in the cold, grassy plain. The plant fossil record from this high-altitude site in southern Peru contains dramatic reminders that the environment in the Andes mountains changed drastically during the past 10 million years, but not in the ways that climate models of the past suggest. Findings from the expedition are presented in the journal "This tree and the hundreds of fossil wood, leaf and pollen samples we collected on the expedition, reveal that when these plants were alive the ecosystem was more humid -- even more humid than climate models of the past predicted," said Camila Martinez, a fellow at STRI, who recently finished her doctorate at Cornell University. "There is probably no comparable modern ecosystem, because temperatures were higher when these fossils were deposited 10 million years ago."The anatomy of the petrified (permineralized) wood the researchers found is very much like wood anatomy in low-elevation tropical forests today. Indeed, the altitude then was probably only 2,000 meters above sea level.But that ecosystem did not last for long. Today, the arid, intermountain plateau lies at 4,000 meters above sea level.Five million year-old fossils from the same sites confirmed that the Puna ecosystem that now dominates the Andes' high mountain plateaus had been born: the younger pollen samples were mostly from grasses and herbs, rather than from trees. Leaf material was from ferns, herbs and shrubs, indicating that the plateau had already risen to its current altitude."The fossil record in the region tells us two things: both the altitude and the vegetation changed dramatically over a relatively short period of time, supporting a hypothesis that suggests the tectonic uplift of this region occurred in rapid pulses," said Carlos Jaramillo, STRI staff scientist and project leader."Andean uplift played an important role in shaping the climate of South America, but the relationship between the rise of the Andes, local climates and vegetation is still not well understood," Martinez said. "By the end of this century, changes in temperature and atmospheric carbon dioxide concentrations will again approximate the conditions 10 million years ago. Understanding the discrepancies between climate models and data based on the fossil record help us to elucidate the driving forces controlling the current climate of the Altiplano, and, ultimately, the climate across the South American continent.Author affiliations include: STRI; Cornell University; CNRS, EPHE, IRD, Montpellier; Universidad Nacional Autónoma de México; Museo de Historia Natural, Lima, Peru; University of Rochester, Rochester, New York; and the Florida Institute of Technology.
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Climate
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August 28, 2020
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https://www.sciencedaily.com/releases/2020/08/200828115359.htm
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How Neanderthals adjusted to climate change
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Climate change occurring shortly before their disappearance triggered a complex change in the behaviour of late Neanderthals in Europe: they developed more complex tools. This is the conclusion reached by a group of researchers from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and Università degli Studi die Ferrara (UNIFE) on the basis of finds in the Sesselfelsgrotte cave in Lower Bavaria.
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Neanderthals lived approximately 400,000 to 40,000 years ago in large areas of Europe and the Middle East, even as far as the outer edges of Siberia. They produced tools using wood and glass-like rock material, which they also sometimes combined, for example to make a spear with a sharp and hard point made of stone.From approximately 100,000 years ago, their universal cutting and scraping tool was a knife made of stone, the handle consisting of a blunt edge on the tool itself. These Keilmesser (backed, asymmetrical bifacially-shaped knives) were available in various shapes, leading researchers to wonder why the Neanderthals created such a variety of knives? Did they use different knives for different tasks or did the knives come from different sub-groups of Neanderthals? This was what the international research project hoped to find out."Keilmesser are a reaction to the highly mobile lifestyle during the first half of the last ice age. As they could be sharpened again as and when necessary, they were able to be used for a long time -- almost like a Swiss army knife today," says Prof. Dr. Thorsten Uthmeier from the Institute of Prehistory and Early History at FAU. "However, people often forget that bi-facially worked knives were not the only tools Neanderthals had. Backed knives from the Neanderthal period are surprisingly varied," adds his Italian colleague Dr. Davide Delpiano from Sezione di Scienze Preistoriche e Antropologiche at UNIFE. "Our research uses the possibilities offered by digital analysis of 3D models to discover similarities and differences between the various types of knives using statistical methods."The two researchers investigated artefacts from one of the most important Neanderthal sites in Central Europe, the Sesselfelsgrotte cave in Lower Bavaria. During excavations in the cave conducted by the Institute of Prehistory and Early History at FAU, more than 100,000 artefacts and innumerable hunting remains left behind by the Neanderthals have been found, even including evidence of a Neanderthal burial. The researchers have now analysed the most significant knife-like tools using 3D scans produced in collaboration with Prof. Dr. Marc Stamminger and Dr. Frank Bauer from the Chair of Visual Computing at the Department of Computer Science at FAU. They allow the form and properties of the tool to be recorded extremely precisely."The technical repertoire used to create Keilmesser is not only direct proof of the advanced planning skills of our extinct relatives, but also a strategical reaction to the restrictions imposed upon them by adverse natural conditions," says Uthmeier, FAU professor for Early Prehistory and Archaeology of Prehistoric Hunters and Gatherers.What Uthmeier refers to as 'adverse natural conditions' are climate changes after the end of the last interglacial more than 100,000 years ago. Particularly severe cold phases during the following Weichsel glacial period began more than 60,000 years ago and led to a shortage of natural resources. In order to survive, the Neanderthals had to become more mobile than before, and adjust their tools accordingly.The Neanderthals probably copied the functionality of unifacial backed knives, which are only shaped on one side, and used these as the starting point to develop bi-facially formed Keilmesser shaped on both sides. "This is indicated in particular by similarities in the cutting edge, which consists in both instances of a flat bottom and a convex top, which was predominantly suited for cutting lengthwise, meaning that it is quite right to refer to the tool as a knife," says Davide Delpiano from UNIFE.Both types of knife -- the simpler older version and the newer, significantly more complex version -- obviously have the same function. The most important difference between the two tools investigated in this instance is the longer lifespan of bi-facial tools. Keilmesser therefore represent a high-tech concept for a long-life, multi-functional tool, which could be used without any additional accessories such as a wooden handle."Studies from other research groups seem to support our interpretation," says Uthmeier. "Unlike some people have claimed, the disappearance of the Neanderthals cannot have been a result of a lack of innovation or methodical thinking."
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August 28, 2020
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https://www.sciencedaily.com/releases/2020/08/200828102157.htm
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Where marine heatwaves will intensify fastest: New analysis
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The world's strongest ocean currents, which play key roles in fisheries and ocean ecosystems, will experience more intense marine heatwaves than the global average over coming decades, according to a paper published today in
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Sections of Australia's Leeuwin current and East Australian Current; the United States Gulf Stream; Japan's Kuroshio current; and the most powerful ocean current of all, the Antarctic Circumpolar Current, will all see the intensity of heatwave events ratchet up over the next 30 years.However, while the intensity of individual marine heatwave events in these areas is likely to increase faster than the global average, the number of marine heatwave days appear to increase at a lower than average rate. And what happens around these currents is even more interesting."We know marine heatwaves are on the rise globally, but policymakers, fisheries experts, aquaculture industries and ecologists need to know how this will play out at regional levels, especially in terms of where they will occur and how much hotter they will be," said lead author from the ARC Centre of Excellence for Climate Extremes Dr Hakase Hayashida."Our detailed modelling is the first step in peeling back these layers, revealing the temperature variation that occurs across these currents and around them, indicating where the sharpest rises in marine heatwaves are likely to occur."For instance, we found intense marine heatwaves were more likely to form well off the coast of Tasmania, while along the Gulf Stream more intense marine heatwaves start to appear more frequently close to the shore along the stretch of coastline from the state of Virginia to New Brunswick. This will almost certainly change ecosystems in these regions."The key to this research was the use of two near-global high-resolution (1/10o) simulations over current and future periods developed by CSIRO Ocean Downscaling Strategic Project, which could reproduce eddies 100km across and generate realistic boundary currents and fronts.. This detailed approach revealed the, sometimes, stark regional variability in ocean temperature extremes much more variable than coarser global climate models.The researchers confirmed the accuracy of their model by comparing the detailed model outputs with observations from 1982-2018. They then used the same high-resolution model to project how marine heatwaves would alter with climate change out to 2050.In every western boundary current they examined, more intense marine heatwaves appeared. In general marine heatwaves also occurred more frequently.But on the edge of these currents, it was a different story. Eddies that spun off from the main current created areas where the increases in numbers of heatwave days were lower than average and even some regions where heatwave intensity declined."Like so many aspects of the climate system, the warming of the oceans isn't the same everywhere, which means the ecology will respond differently to global warming, depending on location," said Assoc Prof Peter Strutton."Detailed modelling like this is the first step in understanding which ecosystems will thrive or decline, how the productivity of the ocean will change, and those parts of the food chain most likely to be affected. This is exactly the kind of knowledge we need to adapt to the inevitable consequences of global warming."
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Climate
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August 28, 2020
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https://www.sciencedaily.com/releases/2020/08/200828081046.htm
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Fidelity of El Niño simulation matters for predicting future climate
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A new study led by University of Hawai'i at Manoa researchers, published in the journal
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Trade winds and the temperatures in the tropical Pacific Ocean experience large changes from year to year due to the El Niño-Southern Oscillation (ENSO), affecting weather patterns across the globe. For instance, if the tropical Pacific is warmer and trade winds are weaker than usual -- an El Niño event -flooding in California typically occurs and monsoon failures in India and East Asia are detrimental to local rice production. In contrast, during a La Niña the global weather patterns reverse with cooler temperatures and stronger trade winds in the tropical Pacific. These natural climate swings affect ecosystems, fisheries, agriculture, and many other aspects of human society.Computer models that are used for projecting future climate correctly predict global warming due to increasing greenhouse gas emissions as well as short-term year-to-year natural climate variations associated with El Niño and La Niña."There is, however, some model discrepancy on how much the tropical Pacific will warm," said Malte Stuecker, co-author and assistant professor in the Department of Oceanography and International Pacific Research Center at UH Manoa. "The largest differences are seen in the eastern part of the tropical Pacific, a region that is home to sensitive ecosystems such as the Galapagos Islands. How much the eastern tropical Pacific warms in the future will not only affect fish and wildlife locally but also future weather patterns in other parts of the world."Researchers have been working for decades to reduce the persistent model uncertainties in tropical Pacific warming projections.Many climate models simulate El Niño and La Niña events of similar intensity. In nature, however, the warming associated with El Niño events tends to be stronger than the cooling associated with La Niña. In other words, while in most models El Niño and La Niña are symmetric, they are asymmetric in nature.In this new study, the scientists analyzed observational data and numerous climate model simulations and found that when the models simulate the subsurface ocean current variations more accurately, the simulated asymmetry between El Niño and La Niña increases -- becoming more like what is seen in nature."Identifying the models that simulate these processes associated with El Niño and La Niña correctly in the current climate can help us reduce the uncertainty of future climate projections," said corresponding lead author Michiya Hayashi, a research associate at the National Institute for Environmental Studies, Japan, and a former postdoctoral researcher at UH Manoa supported by the Japan Society for the Promotion of Science (JSPS) Overseas Research Fellowships. "Only one-third of all climate models can reproduce the strength of the subsurface current and associated ocean temperature variations realistically.""Remarkably, in these models we see a very close relationship between the change of future El Niño and La Niña intensity and the projected tropical warming pattern due to greenhouse warming," noted Stuecker.That is, the models within the group that simulate a future increase of El Niño and La Niña intensity show also an enhanced warming trend in the eastern tropical Pacific due to greenhouse warming. In contrast, the models that simulate a future decrease of El Niño and La Niña intensity show less greenhouse gas-induced warming in the eastern part of the basin. The presence of that relationship indicates that those models are capturing a mechanism known to impact climate -- signifying that those models are more reliable. This relationship totally disappears in the two-thirds of climate models that cannot simulate the subsurface ocean current variations correctly."Correctly simulating El Niño and La Niña is crucial for projecting climate change in the tropics and beyond. More research needs to be conducted to reduce the biases in the interactions between wind and ocean so that climate models can generate El Niño -- La Niña asymmetry realistically," added Fei-Fei Jin, co-author and professor in the Department of Atmospheric Sciences at UH Manoa."The high uncertainty in the intensity change of El Niño and La Niña in response to greenhouse warming is another remaining issue," said Stuecker. "A better understanding of Earth's natural climate swings such as El Niño and La Niña will result in reducing uncertainty in future climate change in the tropics and beyond."
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Climate
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August 28, 2020
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https://www.sciencedaily.com/releases/2020/08/200827141302.htm
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Using the past to maintain future biodiversity
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New research shows that safeguarding species and ecosystems and the benefits they provide for society against future climatic change requires effective solutions which can only be formulated from reliable forecasts.
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An international team of scientists led by researchers from the University of Adelaide and University of Copenhagen, has identified and examined past warming events similar to those anticipated in the coming decades, to better understand how species and ecosystems will cope."Reference periods in Earth's history serve as natural laboratories for understanding biodiversity responses to climate change and improving strategies for conservation under ongoing and future climate change," says lead author Associate Professor Damien Fordham from the University of Adelaide's Environment Institute.Approximately 40 per cent of terrestrial ecosystems are projected to have experienced shifts in temperature during the past 21,000 years that are similar in pace and magnitude to regional-scale future forecasts."Studying locations in regions such as the Arctic, Eurasia, the Amazon and New Zealand can inform numerous international conservation plans for species and ecosystems around the world," says Associate Professor Fordham."Using fossil and molecular data from these areas, together with advanced computational approaches, we have identified biological responses to potentially dangerous rates of climatic change.""This new knowledge from the past tells us that terrestrial biodiversity will experience significant changes in response to future global warming. These include wide-scale species declines, threatening the goods and services ecosystems provide to humanity."Associate Professor David Nogues-Bravo from the University of Copenhagen was co-author of the study which is published in the journal "Beyond intrinsic knowledge gain, this integrative research is providing relevant context and case studies that can minimize biodiversity loss from climate change," he says."This includes identifying what causes some species to be more prone to climate-driven extinction than others, and how to improve early-warning systems signalling population collapse, extinction or ecosystem shifts as a result of climate change."The team emphasises that integrating knowledge of biodiversity responses to past warming events into 21st century environmental management demands clear guidelines."Ongoing climate change poses an important challenge for biodiversity management, and our research shows how the recent geological past can inform effective conservation practice and policy," says co-author Stephen Jackson from the U.S. Geological Survey."Conservation biologists are now taking full advantage of the long-term history of the planet as recorded in paleo-archives, such as those gathered by our team, to understand biological responses to abrupt climate changes of the past, quantify trends, and develop scenarios of future biodiversity loss from climate change," says Associate Professor Fordham.The research is part of a global exercise, involving a large number of academic institutions and the International Union for the Conservation of Nature, covering a wide range of species, ecosystems and regions.
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Climate
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August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827172100.htm
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Songbirds reduce reproduction to help survive drought
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With climate change heating the globe, drought more frequently impacts the reproduction and survival of many animal species.
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New research from the University of Montana suggests tropical songbirds in both the Old and New Worlds reduce reproduction during severe droughts, and this -- somewhat surprisingly -- may actually increase their survival rates.The work was published Aug. 24 in the journal "We were extremely surprised to find that not only did reductions in breeding activity mitigate costs to survival, many long-lived species actually experienced higher survival rates during the drought year than during non-drought years," said Martin, assistant unit leader of UM's Montana Cooperative Wildlife Research Unit. "In contrast, shorter-lived species that kept breeding during droughts faced strong reductions in survival."Martin has spent his career venturing into remote jungles and living there for months to study the lives of birds. For this work, he and Mouton studied 38 different bird species in Venezuela and Malaysia over multiple years. There was one drought year for each field site, and the authors modeled future population results for the birds using three different climate change scenarios.They knew behavioral responses to drought might determine the relative impacts on survival and reproduction. At the jungle study sites, researchers located and monitored nests of all species over many years to examine reproductive activity prior to and during the droughts. They also banded birds with colored material and used intensive re-sighting of these birds to obtain rigorous estimates of survival.The researchers found drought reduced reproduction an average of 36% in the 20 Malaysian species and 52% in the 18 Venezuelan species."The negative impacts of drought on survival are well documented," Martin said. "We therefore also expected the droughts to reduce survival, but thought that the reduced breeding activity might limit the decrease in survival."He said they found the population impacts of droughts were largely nullified by the reproductive behavioral shifts in longer-lived species, but shorter-lived species saw less of a benefit."Overall, our results have several major implications," Martin said. "First, we show that understanding behavioral responses to drought are critical for predicting population responses. Behavioral responses to environmental conditions can help buffer the most sensitive vital rates for a given species and mitigate the overall effect on fitness."Second, our results provide unique support to the idea that reproduction can negatively affect survival," he said. "This idea of a 'cost of reproduction' is central to life history theory but only rarely documented in wild populations."Finally, long-lived species are argued to be most sensitive to climate change, but the UM research suggests that many longer-lived species actually may be more resilient to drought impacts of climate change than previously expected."Ultimately, we hope our study can help motivate future studies into behavioral and demographic responses to shifting patterns of rainfall in more species so we can better anticipate the different impacts of climate change among species," Martin said.
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Climate
| 2,020 |
August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827141241.htm
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Civilization may need to 'forget the flame' to reduce CO2 emissions
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Just as a living organism continually needs food to maintain itself, an economy consumes energy to do work and keep things going. That consumption comes with the cost of greenhouse gas emissions and climate change, though. So, how can we use energy to keep the economy alive without burning out the planet in the process?
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In a paper in "How do we achieve a steady-state economy where economic production exists, but does not continually increase our size and add to our energy demands?" Garrett says. "Can we survive only by repairing decay, simultaneously switching existing fossil infrastructure to a non-fossil appetite? Can we forget the flame?"Garrett is an atmospheric scientist. But he recognizes that atmospheric phenomena, including rising carbon dioxide levels and climate change, are tied to human economic activity. "Since we model the earth system as a physical system," he says, "I wondered whether we could model economic systems in a similar way."He's not alone in thinking of economic systems in terms of physical laws. There's a field of study, in fact, called thermoeconomics. Just as thermodynamics describe how heat and entropy (disorder) flow through physical systems, thermoeconomics explores how matter, energy, entropy and information flow through human systems.Many of these studies looked at correlations between energy consumption and current production, or gross domestic product. Garrett took a different approach; his concept of an economic system begins with the centuries-old idea of a heat engine. A heat engine consumes energy at high temperatures to do work and emits waste heat. But it only consumes. It doesn't grow.Now envision a heat engine that, like an organism, uses energy to do work not just to sustain itself but also to grow. Due to past growth, it requires an ever-increasing amount of energy to maintain itself. For humans, the energy comes from food. Most goes to sustenance and a little to growth. And from childhood to adulthood our appetite grows. We eat more and exhale an ever-increasing amount of carbon dioxide."We looked at the economy as a whole to see if similar ideas could apply to describe our collective maintenance and growth," Garrett says. While societies consume energy to maintain day to day living, a small fraction of consumed energy goes to producing more and growing our civilization."We've been around for a while," he adds. "So it is an accumulation of this To test this hypothesis, Garrett and his colleagues used economic data from 1980 to 2017 to quantify the relationship between past cumulative economic production and the current rate at which we consume energy. Regardless of the year examined, they found that every trillion inflation-adjusted year 2010 U.S. dollars of economic worldwide production corresponded with an enlarged civilization that required an additional 5.9 gigawatts of power production to sustain itself . In a fossil economy, that's equivalent to around 10 coal-fired power plants, Garrett says, leading to about 1.5 million tons of COThey came to two surprising conclusions. First, although improving efficiency through innovation is a hallmark of efforts to reduce energy use and greenhouse gas emissions, efficiency has the side effect of making it easier for civilization to grow and consume more.Second, that the current rates of world population growth may not be the cause of rising rates of energy consumption, but a symptom of past efficiency gains."Advocates of energy efficiency for climate change mitigation may seem to have a reasonable point," Garrett says, "but their argument only works if civilization maintains a fixed size, which it doesn't. Instead, an efficient civilization is able to grow faster. It can more effectively use available energy resources to make more of everything, including people. Expansion of civilization accelerates rather than declines, and so do its energy demands and COSo what do those conclusions mean for the future, particularly in relation to climate change? We can't just stop consuming energy today any more than we can erase the past, Garrett says. "We have inertia. Pull the plug on energy consumption and civilization stops emitting but it also becomes worthless. I don't think we could accept such starvation."But is it possible to undo the economic and technological progress that have brought civilization to this point? Can we, the species who harnessed the power of fire, now "forget the flame," in Garrett's words, and decrease efficient growth?"It seems unlikely that we will forget our prior innovations, unless collapse is imposed upon us by resource depletion and environmental degradation," he says, "which, obviously, we hope to avoid."So what kind of future, then, does Garrett's work envision? It's one in which the economy manages to hold at a steady state -- where the energy we use is devoted to maintaining our civilization and not expanding it.It's also one where the energy of the future can't be based on fossil fuels. Those have to stay in the ground, he says."At current rates of growth, just to maintain carbon dioxide emissions at their current level will require rapidly constructing renewable and nuclear facilities, about one large power plant a day. And somehow it will have to be done without inadvertently supporting economic production as well, in such a way that fossil fuel demands also increase."It's a "peculiar dance," he says, between eliminating the prior fossil-based innovations that accelerated civilization expansion, while innovating new non-fossil fuel technologies. Even if this steady-state economy were to be implemented immediately, stabilizing COBy looking at the global economy through a thermodynamic lens, Garrett acknowledges that there are unchangeable realities. Any form of an economy or civilization needs energy to do work and survive. The trick is balancing that with the climate consequences."Climate change and resource scarcity are defining challenges of this century," Garrett says. "We will not have a hope of surviving our predicament by ignoring physical laws."This study marks the beginning of the collaboration between Garrett, Grasselli and Keen. They're now working to connect the results of this study with a full model for the economy, including a systematic investigation of the role of matter and energy in production."Tim made us focus on a pretty remarkable empirical relationship between energy consumption and cumulative economic output," Grasselli says. "We are now busy trying to understand what this means for models that include notions that are more familiar to economists, such as capital, investment and the always important question of monetary value and inflation."
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Climate
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August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827122115.htm
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Artificial intelligence learns continental hydrology
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Changes to water masses which are stored on the continents can be detected with the help of satellites. The data sets on the Earth's gravitational field which are required for this, stem from the GRACE and GRACE-FO satellite missions. As these data sets only include the typical large-scale mass anomalies, no conclusions about small scale structures, such as the actual distribution of water masses in rivers and river branches, are possible. Using the South American continent as an example, the Earth system modellers at the German Research Centre for Geosciences GFZ, have developed a new Deep-Learning-Method, which quantifies small as well as large-scale changes to the water storage with the help of satellite data. This new method cleverly combines Deep-Learning, hydrological models and Earth observations from gravimetry and altimetry.
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So far it is not precisely known, how much water a continent really stores. The continental water masses are also constantly changing, thus affecting the Earth's rotation and acting as a link in the water cycle between atmosphere and ocean. Amazon tributaries in Peru, for example, carry huge amounts of water in some years, but only a fraction of it in others. In addition to the water masses of rivers and other bodies of fresh water, considerable amounts of water are also found in soil, snow and underground reservoirs, which are difficult to quantify directly.Now the research team around primary author Christopher Irrgang developed a new method in order to draw conclusions on the stored water quantities of the South American continent from the coarsely-resolved satellite data. "For the so called down-scaling, we are using a convolutional neural network, in short CNN, in connection with a newly developed training method," Irrgang says. "CNNs are particularly well suited for processing spatial Earth observations, because they can reliably extract recurrent patterns such as lines, edges or more complex shapes and characteristics."In order to learn the connection between continental water storage and the respective satellite observations, the CNN was trained with simulation data of a numerical hydrological model over the period from 2003 until 2018. Additionally, data from the satellite altimetry in the Amazon region was used for validation. What is extraordinary, is that this CNN continuously self-corrects and self-validates in order to make the most accurate statements possible about the distribution of the water storage. "This CNN therefore combines the advantages of numerical modelling with high-precision Earth observation" according to Irrgang.The researchers' study shows that the new Deep-Learning-Method is particularly reliable for the tropical regions north of the -20° latitude on the South American continent, where rain forests, vast surface waters and also large groundwater basins are located. Same as for the groundwater-rich, western part of South America's southern tip. The down-scaling works less well in dry and desert regions. This can be explained by the comparably low variability of the already low water storage there, which therefore only have a marginal effect on the training of the neural network. However, for the Amazon region, the researchers were able to show that the forecast of the validated CNN was more accurate than the numerical model used.In future, large-scale as well as regional analysis and forecasts of the global continental water storage will be urgently needed. Further development of numerical models and the combination with innovative Deep-Learning-Methods will take up a more important role in this, in order to gain comprehensive insight into continental hydrology. Aside from purely geophysical investigations, there are many other possible applications, such as studying the impact of climate change on continental hydrology, the identification of stress factors for ecosystems such as droughts or floods, and the development of water management strategies for agricultural and urban regions.
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Climate
| 2,020 |
August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827122110.htm
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Ocean acidification causing coral 'osteoporosis' on iconic reefs
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Scientists have long suspected that ocean acidification is affecting corals' ability to build their skeletons, but it has been challenging to isolate its effect from that of simultaneous warming ocean temperatures, which also influence coral growth. New research from the Woods Hole Oceanographic Institution (WHOI) reveals the distinct impact that ocean acidification is having on coral growth on some of the world's iconic reefs.
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In a paper published Aug. 27, 2020, in the journal "This is the first unambiguous detection and attribution of ocean acidification's impact on coral growth," says lead author and WHOI scientist Weifu Guo. "Our study presents strong evidence that 20th century ocean acidification, exacerbated by reef biogeochemical processes, had measurable effects on the growth of a keystone reef-building coral species across the Great Barrier Reef and in the South China Sea. These effects will likely accelerate as ocean acidification progresses over the next several decades."Roughly a third of global carbon dioxide emissions are absorbed by the ocean, causing an average 0.1 unit decline in seawater pH since the pre-industrial era. This phenomenon, known as ocean acidification, has led to a 20 percent decrease in the concentration of carbonate ions in seawater. Animals that rely on calcium carbonate to create their skeletons, such as corals, are at risk as ocean pH continues to decline. Ocean acidification targets the density of the skeleton, silently whittling away at the coral's strength, much like osteoporosis weakens bones in humans."The corals aren't able to tell us what they're feeling, but we can see it in their skeletons," said Anne Cohen, a WHOI scientist and co-author of the study. "The problem is that corals really need the strength they get from their density, because that's what keeps reefs from breaking apart. The compounding effects of temperature, local stressors, and now ocean acidification will be devastating for many reefs."In their investigation, Guo and his co-authors examined published data collected from the skeletons of Porites corals -- a long-living, dome-shaped species found across the Indo-Pacific -- combined with new three-dimensional CT scan images of Porites from reefs in the central Pacific Ocean. Using these skeletal archives, which date back to 1871, 1901, and 1978, respectively, the researchers established the corals' annual growth and density. They plugged this information, as well as historical temperature and seawater chemistry data from each reef, into a model to predict the corals' response to constant and changing environmental conditions.The authors found that ocean acidification caused a significant decline in Porites skeletal density in the Great Barrier Reef (13 percent) and the South China Sea (7 percent), starting around 1950. Conversely, they found no impact of ocean acidification on the same types of corals in the Phoenix Islands and central Pacific, where the protected reefs are not as impacted by pollution, overfishing, runoff from land.While carbon dioxide emissions are the largest driver of ocean acidification on a global scale, the authors point out that sewage and runoff from land can exacerbate the effect, causing even further reductions of seawater pH on nearby reefs. The authors attribute the declining skeletal density of corals on the Great Barrier Reef and South China Sea to the combined effects of ocean acidification and runoff. Conversely, reefs in marine protected areas of the central Pacific have so far been shielded from these impacts."This method really opens a new way to determine the impact of ocean acidification on reefs around the world," said Guo. "Then we can focus on the reef systems where we can potentially mitigate the local impacts and protect the reef."Co-authors of the paper include Rohit Bokade (Northeastern University), Nathaniel Mollica (MIT-WHOI joint program), and Muriel Leung (University of Pennsylvania), as well as Russell Brainard of King Abdullah University of Science and Technology and formerly at the Coral Reef Ecosystem Division of the Pacific Islands Fisheries Science Center.Funding for this research was provided by the National Science Foundation, the Tiffany & Co. Foundation, the Robertson Foundation, the Atlantic Donor Advised Fund, and WHOI's Investment in Science Fund.An innovative numerical model developed by researchers at the Woods Hole Oceanographic Institution demonstrates the distinct impact of ocean acidification -- separate from ocean warming -- on coral growth.The model shows that ocean acidification has caused a 13 percent decline in the skeletal density of Porites corals in the Great Barrier Reef, and a 7 percent decline in the South China Sea since 1950.Pollution and land runoff can exacerbate the effects of ocean acidification, causing corals in local reefs to weaken more quickly than those located farther away from human settlements.A global-scale investigation of coral CT scans could help to target protections for vulnerable reefs.
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Climate
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August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827101814.htm
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Misconceptions about weather and seasonality impact COVID-19 response
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Misconceptions about the way climate and weather impact exposure and transmission of SARS-CoV-2, the virus that causes COVID-19, create false confidence and have adversely shaped risk perceptions, say a team of Georgetown University researchers.
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"Future scientific work on this politically-fraught topic needs a more careful approach," write the scientists in a "Comment" published today in The authors include global change biologist Colin J. Carlson, PhD, an assistant professor at Georgetown's Center for Global Health Science and Security; senior author Sadie Ryan, PhD, a medical geographer at the University of Florida; Georgetown disease ecologist Shweta Bansal, PhD; and Ana C. R. Gomez, a graduate student at UCLA.The research team says current messaging on social media and elsewhere "obscures key nuances" of the science around COVID-19 and seasonality."Weather probably influences COVID-19 transmission, but not at a scale sufficient to outweigh the effects of lockdowns or re-openings in populations," the authors write.The authors strongly discourage policy be tailored to current understandings of the COVID-climate link, and suggest a few key points:"With current scientific data, COVID-19 interventions cannot currently be planned around seasonality," the authors conclude.
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Climate
| 2,020 |
August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827102132.htm
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Stop! Grand theft water
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An international team of researchers led by the University of Adelaide has developed a new method to better understand the drivers of water theft, a significant worldwide phenomenon, and deterrents to help protect this essential resource.
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In a paper published in Lead author, Dr Adam Loch, Senior Lecturer at the University of Adelaide's Centre for Global Food and Resources, said that water theft is a research topic that has not received a lot of coverage due to a lack of data and because often those stealing water are poor, vulnerable and at risk in developing countries."But theft also occurs in the developed world, especially in agricultural settings," said Dr Loch."According to Interpol, thieves steal as much as 30-50 per cent of the world's water supply annually -- a big number."Compounding this problem is the fact that, as the scarcity of our most precious resource increases due to climate and other challenges, so too do the drivers for water theft."Drivers to water theft include social attitudes, institutions and future supply uncertainty.With the novel framework and model, water managers can test the impact of changes to detection, prosecution and conviction systems, and accurately measure the effectiveness of current penalties which may not provide an effective deterrent."If users are motivated to steal water because it is scarce, and they need it to keep a crop alive, then the opportunity cost of that water may far exceed the penalty, and theft will occur," said Dr Loch.The case studies also provide evidence that where authorities fail to support detection and prosecution theft will increase, and stronger deterrents may be needed to dissuade users from stealing water to maximise profits."In Spain regulators were assaulted by users when they tried to stop them from stealing water; in the US marijuana growers stole water from fire hydrants and the police felt powerless to do anything about it," said Dr Loch.Researchers said there are many cases of water theft that could be studied using the framework and model -- and they encourage institutions to use the free tools located within the paper's supplementary materials."Much of the world's focus right now is on water efficiency investments, which might achieve (at best) between 10-20 per cent savings for water managers. But if we can recover 30-50% of 'lost' water, targeting those who steal for profit making, then that would be good for our water supply, and good for us," said Dr Loch.
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Climate
| 2,020 |
August 26, 2020
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https://www.sciencedaily.com/releases/2020/08/200826151258.htm
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Native desert bighorn sheep in ecologically intact areas are less vulnerable to climate change
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In the American Southwest, native desert bighorn sheep populations found in landscapes with minimal human disturbance, including several national parks, are less likely to be vulnerable to climate change, according to a new study led by Oregon State University.
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The study, published in the journal The researchers found that the least vulnerable bighorn populations are primarily in and around Death Valley National Park and Grand Canyon National Park. The results suggest that protecting these landscapes should be a priority for native bighorn conservation, said lead author Tyler Creech, an OSU graduate now at the Center for Large Landscape Conservation in Bozeman, Montana.Meanwhile, the researchers determined that the populations with the highest overall vulnerability are primarily located outside of national park units in the southern Mojave Desert and in southeastern Utah.In the study, the researchers analyzed the genetic structure and diversity of bighorn sheep populations and how connected they are to other populations, both genetically and geographically, and used that information to infer their vulnerability to a changing climate."We used DNA samples from bighorn sheep to tell us how genetically diverse populations are," Creech said. "The populations that are less genetically diverse and less connected to their neighbors are more likely to be negatively impacted by climate change.""Genetic diversity allows populations to adapt to new environments," said study co-author Clint Epps, a wildlife biologist and associate professor in the Department of Fisheries and Wildlife in OSU's College of Agricultural Sciences. "This study highlights the important role our national park units can play in keeping these populations up as the climate changes."The researchers primarily used fecal pellet samples to obtain DNA from up to 85 individual bighorn in each population, and combined genetic datasets from multiple projects covering different portions of the study area, dating back to 2000. After the samples were processed and genotyped, they grouped the individuals into populations based on the locations where they were sampled, then quantified the isolation and genetics of each population.They also considered how exposure to harsher climatic conditions within bighorn sheep habitat "patches" could influence populations' vulnerability. Desert bighorn sheep live in some of the hottest and driest landscapes in the U.S., and climate modeling shows those areas could get hotter and drier.To assess climate change exposure, they used an index known as "forward climate velocity," which indicates the speed at which species must migrate to maintain constant climate conditions. They considered two greenhouse gas emissions scenarios for the 2050s developed by the Intergovernmental Panel on Climate Change, one that models moderate emissions and the other that models high emissions."We believe this approach was suitable for assessing relative exposure of desert bighorn populations across a large geographic range because although temperature and precipitation are known to influence fitness of desert bighorn sheep, the specific climatic conditions to which bighorn are most sensitive are not fully understood and may vary geographically," Creech said.
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Climate
| 2,020 |
August 26, 2020
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https://www.sciencedaily.com/releases/2020/08/200826141405.htm
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How cold was the ice age? Researchers now know
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A University of Arizona-led team has nailed down the temperature of the last ice age -- the Last Glacial Maximum of 20,000 years ago -- to about 46 degrees Fahrenheit.
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Their findings allow climate scientists to better understand the relationship between today's rising levels of atmospheric carbon dioxide -- a major greenhouse gas -- and average global temperature.The Last Glacial Maximum, or LGM, was a frigid period when huge glaciers covered about half of North America, Europe and South America and many parts of Asia, while flora and fauna that were adapted to the cold thrived."We have a lot of data about this time period because it has been studied for so long," said Jessica Tierney, associate professor in the UArizona Department of Geosciences. "But one question science has long wanted answers to is simple: How cold was the ice age?"Tierney is lead author of a paper published today in "In your own personal experience that might not sound like a big difference, but, in fact, it's a huge change," Tierney said.She and her team also created maps to illustrate how temperature differences varied in specific regions across the globe."In North America and Europe, the most northern parts were covered in ice and were extremely cold. Even here in Arizona, there was big cooling," Tierney said. "But the biggest cooling was in high latitudes, such as the Arctic, where it was about 14 C (25 F) colder than today."Their findings fit with scientific understanding of how Earth's poles react to temperature changes."Climate models predict that the high latitudes will get warmer faster than low latitudes," Tierney said. "When you look at future projections, it gets really warm over the Arctic. That's referred to as polar amplification. Similarly, during the LGM, we find the reverse pattern. Higher latitudes are just more sensitive to climate change and will remain so going forward."Knowing the temperature of the ice age matters because it is used to calculate climate sensitivity, meaning how much the global temperature shifts in response to atmospheric carbon.Tierney and her team determined that for every doubling of atmospheric carbon, global temperature should increase by 3.4 C (6.1 F), which is in the middle of the range predicted by the latest generation of climate models (1.8 to 5.6 C).Atmospheric carbon dioxide levels during the ice age were about 180 parts per million, which is very low. Before the Industrial Revolution, levels rose to about 280 parts per million, and today they've reached 415 parts per million."The Paris Agreement wanted to keep global warming to no larger than 2.7 F (1.5 C) over pre-industrial levels, but with carbon dioxide levels increasing the way they are, it would be extremely difficult to avoid more than 3.6 F (2 C) of warming," Tierney said. "We already have about 2 F (1.1 C) under our belt, but the less warm we get the better, because the Earth system really does respond to changes in carbon dioxide."Since there were no thermometers in the ice age, Tierney and her team developed models to translate data collected from ocean plankton fossils into sea-surface temperatures. They then combined the fossil data with climate model simulations of the LGM using a technique called data assimilation, which is used in weather forecasting."What happens in a weather office is they measure the temperature, pressure, humidity and use these measurements to update a forecasting model and predict the weather," Tierney said. "Here, we use the Boulder, Colorado-based National Center for Atmospheric Research climate model to produce a hindcast of the LGM, and then we update this hindcast with the actual data to predict what the climate was like."In the future, Tierney and her team plan to use the same technique to recreate warm periods in Earth's past."If we can reconstruct past warm climates," she said, "then we can start to answer important questions about how the Earth reacts to really high carbon dioxide levels, and improve our understanding of what future climate change might hold."The research was supported by the Heisings-Simons Foundation and the National Science Foundation.
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Climate
| 2,020 |
August 26, 2020
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https://www.sciencedaily.com/releases/2020/08/200826141401.htm
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Antarctic ice shelves vulnerable to sudden meltwater-driven fracturing, says study
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A new study says that many of the ice shelves ringing Antarctica could be vulnerable to quick destruction if rising temperatures drive melt water into the numerous fractures that currently penetrate their surfaces. The shelves help slow interior glaciers' slide toward the ocean, so if they were to fail, sea levels around the world could surge rapidly as a result. The study appears this week in the leading journal
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Ice shelves are giant tongues of ice floating on the ocean around the edges of the continent. The vast land-bound glaciers behind them are constantly pushing seaward. But because many shelves are largely confined within expansive bays and gulfs, they are compressed from the sides and slow the glaciers' march -- somewhat like a person in a narrow hallway bracing their arms against the walls to slow someone trying to push past them. But ice shelves experience a competing stress: they stretch out as they approach the ocean. Satellite observations show that, as a result, they rip apart; most are raked with numerous long fractures perpendicular to the direction of stretching. Fractures that form at the surface can be tens of meters deep; others, forming from the bottom, can penetrate the ice hundreds of meters upward. Some fractures are hundreds of meters wide.Currently, most of the shelves are frozen year round, and stable. But scientists project that widespread warming could occur later in the century. And, existing research has shown that even subtle temperature swings can spur widespread melting. This could send melt water surging into the surface fractures. Such surges would potentially cause hydrofracturing-a process in which liquid water, heavier than ice, would violently force the fractures to zip open, and cause the shelf to rapidly disintegrate The new study estimates that 50 to 70 percent of the areas of the ice shelves buttressing the glaciers are vulnerable to such processes."It's not just about melting, but where it's melting," said lead author Ching-Yao Lai, a postdoctoral researcher at Columbia University's Lamont-Doherty Earth Observatory."The ice shelves-that's the weak spot, where the atmosphere, the ice and ocean interact," said study coauthor Jonathan Kingslake, a glaciologist at Lamont-Doherty. "If they fill up with melt water, things can happen very quickly after that, and there could be major consequences for sea levels."Hydrofracturing has already occurred in a few places. Parts of the Larsen Ice Shelf, which had been stable for at least 10,000 years, disintegrated within just days in 1995 and 2002. This was followed by the partial breakup of the Wilkins Ice Shelf in 2008 and 2009. The main agreed-upon causes: hydrofracturing. The Larsen and Wilkins comprise some of the northernmost ice on the continent, and so have been the first to suffer under rising temperatures and seasonal melting.The new study follows a 2017 paper led by Kingslake showing that seasonal ponds and streams on the ice surface are far more common across Antarctica than previously believed; some reach within 375 miles of the South Pole. But most cataloged features are in places not subject to hydrofracturing. The new study shows that, so far, only about 0.6 percent of East Antarctic ice shelves that provide buttressing experience melt-water ponding, making them vulnerable. A much larger percentage would potentially be endangered, if warming takes hold.In collaboration with Cameron Chen, a researcher from Google, Lai trained a machine-learning model to identify ice-shelf fracture locations across Antarctica, to produce the first continent-wide map of such features. Although most fractures now contain no liquid water, the scientists considered future cases in which melt water might fully fill the surface fractures. This allowed them to predict which parts of the shelves would be vulnerable to hydrofracturing, when factoring in the competing forces of compression from the sides, and stretching of the ice from back to front.They calculated that inflow of liquid into the existing fractures could potentially exert enough force to cause widespread hydrofracturing across 50 to 70 percent of the ice-shelf areas that provide buttressing. The main exceptions were smaller, solider areas of ice closest to land, which experience less stress from stretching. The end portions of the shelves, mostly surrounded by open ocean, are also vulnerable, but floating freely as they do, those do not help hold back the glaciers.While the study flashes a warning, the researchers say they cannot predict the ice shelves' behavior with any exactitude. "How fast melt water would form and fill in those cracks is the first question," said Kingslake. He said the worst-case scenario would be that "lots of places will be covered by lots and lots of water by the end of the century." But projections vary widely, depending on which models scientists use, and how vigorously humanity cuts greenhouse gases, or not. The second question is whether particular locations will undergo hydrofracturing, he said. The third question: whether the process would run away, causing the shelf to undergo explosive Larsen-type disintegration.Theodore Scambos, a leading Antarctic glaciologist and the National Snow and Ice Data Center, said the paper "does a great job of pointing to areas where one can say, 'If it floods with melt here, it's likely to break up the shelf." He added that it "has huge implications for sea level" if summer temperatures along the coasts rise."Eventually, all the ice shelves could be covered by melt water," said Lai. "But we don't have a time frame, and there are a lot of big questions left."The study was also coauthored by Martin Wearing of the University of Edinburgh; Pierre Gentine, Harold Li and Julian Spergel of Columbia; and J. Melchior van Wessem of Utrecht University.
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Climate
| 2,020 |
August 26, 2020
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https://www.sciencedaily.com/releases/2020/08/200826141356.htm
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Difficult, complex decisions underpin the future of the world's coral reefs
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Effective solutions to the climate challenge threatening the world's coral reefs require complex decisions about risk and uncertainty, timing, quality versus quantity as well as which species to support for the most robust and productive future, according to a science paper released today.
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Interventions to help coral reefs under global change -- a complex decision challenge, by a group of key scientists from Australia's Reef Restoration and Adaptation Program (RRAP), was today published in The paper warns that while best-practice conventional management is essential, it is unlikely to be enough to sustain coral reefs under continued climate change. Nor is reducing emissions of greenhouse gases, on its own, sufficient any longer.Lead author -- marine biologist and decision scientist Dr Ken Anthony, of the Australian Institute of Marine Science (AIMS) -- said that even with strong action to reduce carbon emissions, global temperatures could stay elevated for decades."Coordinated, novel interventions will most likely be needed -- combined with best-practice conventional reef management and reduced carbon emissions -- to help the Reef become resilient in the face of climate change," he said."Developing new technologies for environmental management and conservation carries some risks but delaying action represents a lost opportunity to sustain the Reef in the best condition possible."Such interventions include local and regional cooling and shading technologies such as brightening clouds to reflect sunlight and shade the reef, assisting the natural evolution of corals to increase their resilience to the changing environment, and measures to support and enhance the natural recovery of damaged reefs.The paper draws parallels between the risk assessment of coral reef interventions and driverless cars and new drugs. It outlines the prioritisation challenges and the trade-offs that need to be weighed."For example, should we aim to sustain minimal coral cover over a very large area of the reef or moderate coral cover over a smaller area?" he said."While the net result of coral area sustained may be the same, it could produce very different ecological outcomes and values for industries like tourism."Spreading efforts thinly could reduce the Reef's capacity to sustain critical ecological functions, while concentrating efforts on a selection of just a few reefs could sustain most of the Reef's tourism industry, which is spatially concentrated."But under severe climate change, preserving more coral cover in smaller areas could reduce the Great Barrier Reef to a fragmented (and therefore vulnerable) network of coral oases in an otherwise desolate seascape."Dr Anthony said prioritising the coral species to be supported by adaptation and restoration measures added to the decision challenge for reef restoration and adaptation."Without significant climate mitigation, sensitive coral species will give way to naturally hardier ones, or to species that can adapt faster," he said."Picking who should be winners, and ultimately who will be losers under continued but uncertain climate change is perhaps the biggest challenge facing R&D programs tasked with developing reef rescue interventions."Co-author and AIMS CEO Dr Paul Hardisty said how interventions were chosen and progressed for research and development would determine what options were available for reef managers and when."Ultimately, we need to consider what society wants, what can be achieved and what opportunities we have for action in a rapidly closing window," he said."It will require exceptional coordination of science, management and policy, and open engagement with the Traditional Owners and the general public. It will also require compromise, because reefs will change under climate change despite our best interventions."RRAP is a partnership of organisations working together to create an innovative toolkit of safe, acceptable, large-scale interventions to helping the Reef resist, adapt to, and recover from the impacts of climate change.In April, the Australian Government announced that an initial $150M would be invested in the RRAP R&D Program following endorsement of a two-year feasibility study. Of this, $100M is through the $443.3 million Great Barrier Reef Foundation -- Reef Trust Partnership with a further $50M in research and scientific contributions from the program partners.Dr Hardisty said RRAP aimed to research and develop new methods for management quickly and safely."We need to be expediently trialling promising interventions now, whatever emissions trajectory the world follows," he said."In this paper we offer a conceptual model to help reef managers frame decision problems and objectives, and to guide effective strategy choices in the face of complexity and uncertainty."1:40 animation -- How can we help the Great Barrier Reef?:
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Climate
| 2,020 |
August 26, 2020
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https://www.sciencedaily.com/releases/2020/08/200826104056.htm
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New study warns: We have underestimated the pace at which the Arctic is melting
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Temperatures in the Arctic Ocean between Canada, Russia and Europe are warming faster than researchers' climate models have been able to predict.
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Over the past 40 years, temperatures have risen by one degree every decade, and even more so over the Barents Sea and around Norway's Svalbard archipelago, where they have increased by 1.5 degrees per decade throughout the period.This is the conclusion of a new study published in "Our analyses of Arctic Ocean conditions demonstrate that we have been clearly underestimating the rate of temperature increases in the atmosphere nearest to the sea level, which has ultimately caused sea ice to disappear faster than we had anticipated," explains Jens Hesselbjerg Christensen, a professor at the University of Copenhagen's Niels Bohr Institutet (NBI) and one of the study's researchers.Together with his NBI colleagues and researchers from the Universities of Bergen and Oslo, the Danish Metrological Institute and Australian National University, he compared current temperature changes in the Arctic with climate fluctuations that we know from, for example, Greenland during the ice age between 120,000-11,000 years ago."The abrupt rise in temperature now being experienced in the Arctic has only been observed during the last ice age. During that time, analyses of ice cores revealed that temperatures over the Greenland Ice Sheet increased several times, between 10 to 12 degrees, over a 40 to 100-year period," explains Jens Hesselbjerg Christensen.He emphasizes that the significance of the steep rise in temperature is yet to be fully appreciated. And, that an increased focus on the Arctic and reduced global warming, more generally, are musts.Climate models ought to take abrupt changes into account Until now, climate models predicted that Arctic temperatures would increase slowly and in a stable manner. However, the researchers' analysis demonstrates that these changes are moving along at a much faster pace than expected."We have looked at the climate models analysed and assessed by the UN Climate Panel. Only those models based on the worst-case scenario, with the highest carbon dioxide emissions, come close to what our temperature measurements show over the past 40 years, from 1979 to today," says Jens Hesselbjerg Christensen.In the future, there ought to be more of a focus on being able to simulate the impact of abrupt climate change on the Arctic. Doing so will allow us to create better models that can accurately predict temperature increases:"Changes are occurring so rapidly during the summer months that sea ice is likely to disappear faster than most climate models have ever predicted. We must continue to closely monitor temperature changes and incorporate the right climate processes into these models," says Jens Hesselbjerg Christensen. He concludes:"Thus, successfully implementing the necessary reductions in greenhouse gas emissions to meet the Paris Agreement is essential in order to ensure a sea-ice packed Arctic year-round."
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Climate
| 2,020 |
August 26, 2020
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https://www.sciencedaily.com/releases/2020/08/200826101635.htm
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Atmospheric scientists study fires to resolve ice question in climate models
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When fossil fuel or biomass burns, soot -- also known as black carbon -- fills the air. Black carbon is an important short-term climate driver because it absorbs solar energy and can affect the formation and composition of clouds.
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The extent of black carbon's impact on clouds has been the subject of debate for 30 years. A study recently published by Colorado State University atmospheric scientists aims to settle the debate and improve climate models.Previous studies done in the laboratory conflicted on whether black carbon was effective at ice nucleation, a process important to cloud formation. Soot particles, like other types of aerosol particles in the air, can act as the foundation for ice crystal growth. Lab results on soot ranged wildly from no ice nucleation activity to efficient ice formation."One reason these results could span such a range is that combustion processes that form black carbon are extremely complicated and differ depending on fuels burned, and on whether combustion is carefully controlled, as in a diesel engine, or uncontrolled, as in wildfires," said Gregory Schill, first author on the study and a former NSF postdoctoral research fellow in the Department of Atmospheric Science.Schill and his colleagues sampled smoke from wildfires and prescribed burns, then filtered out soot particles using a technique he developed with other members of Professor Sonia Kreidenweis and Paul DeMott's research group. This work builds on Schill's previous investigation of black carbon particles from diesel engine exhaust, conducted at the CSU Engines and Energy Conversion Laboratory.Combining the knowledge gained through these experiments, Schill and his colleagues simulated the contributions of black carbon ice-nucleating particles versus other natural sources in a global model. They found black carbon is not as important as previously thought for ice particle formation in mid-level clouds, the clouds most responsible for precipitation over continents.Natural sources, such as dust and sea spray, have more influence on mid-level cloud properties. These cloud attributes variously affect climate by reflecting sunlight, releasing precipitation and determining how long the cloud persists."Our results suggest that black carbon, regardless of fuel types or combustion conditions, have similar ice formation properties in mid-level clouds, and these are less efficient at forming ice compared to other non-anthropogenic sources," Schill said.Atmospheric models have overestimated the role of black carbon as an ice-nucleating particle, and these findings correct that misunderstanding."This provides a clearer picture of the factors, both natural and anthropogenic, that might impact clouds and precipitation in a future climate," Schill said.The study eliminates black carbon as the primary suspect for ice formation from smoke particles but leaves many unanswered questions about how biomass burning affects clouds."Black carbon is only one component of a complex soup that makes up smoke," Schill said. "We know that something in smoke can form ice particles, but we do not fully understand what these cloud seeds are."CSU atmospheric scientists are working on that problem, including a study by the Kreidenweis/DeMott group that addresses biomass burning's contribution of such seeds to cloud levels. This nascent work is based on samples taken during the WE-CAN campaign, in which scientists in research aircraft flew into wildfire smoke. The new study's findings confirm that lofted plumes have the same characteristics Schill found in his ground-based studies.
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Climate
| 2,020 |
August 26, 2020
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https://www.sciencedaily.com/releases/2020/08/200826083032.htm
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Majority of groundwater stores resilient to climate change
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Fewer of the world's large aquifers are depleting than previously estimated, according to a new study by the University of Sussex and UCL.
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Groundwater, the world's largest distributed store of freshwater, plays a critical role in supplying water for irrigation, drinking and industry, and sustaining vital ecosystems.Previous global studies of changes in groundwater storage, estimated using data from the GRACE (Gravity Recovery and Climate Experiment) satellite mission and global models, have concluded that intensifying human water withdrawals in the majority of the world's large aquifer systems are causing a sustained reduction in groundwater storage, depleting groundwater resources.Yet this new study, published in Lead author, Dr Mohammad Shamsudduha, Lecturer in Physical Geography and a member of the Sussex Sustainability Research Programme at the University of Sussex, said: "The cloud of climate change has a silver lining for groundwater resources as it favours greater replenishment from episodic, extreme rainfalls in some aquifers located around the world mainly in dry environments. This new analysis provides a benchmark alongside conventional, ground-based monitoring of groundwater levels to assess changes in water storage in aquifers over time. This information is essential to inform sustainable management of groundwater resources."This new study updates and extends previous analyses, accounting for strong seasonality in groundwater storage in the analysis of trends. It shows that a minority (only 5) of the world's 37 large aquifers is undergoing depletion that requires further attention for better management.Co-author, Professor of Hydrogeology, Richard Taylor from UCL Geography, said: "The findings do not deny that groundwater depletion is occurring in many parts of the world but that the scale of this depletion, frequently associated with irrigation in drylands, is more localised than past studies have suggested and often occurs below a large (~100 000 km2) 'footprint' of mass changes tracked by a pair of GRACE satellites."For the majority, trends are non-linear and irregular, exhibiting considerable variability in volume over time. The study shows further that variability in groundwater storage in drylands is influenced positively and episodically by years of extreme (>90th percentile) precipitation.For example, in the Great Artesian Basin of Australia, extreme seasonal rainfall over two successive summers in 2010 and 2011 increased groundwater storage there by ~90 km3, more than ten times total annual freshwater withdrawals in the UK. Elsewhere in the Canning Basin of Australia, however, groundwater depletion is occurring at a rate of 4.4 km3 each year that is associated with its use in the extraction of iron ore.To avoid continued depletion of aquifers, the study promotes sustainable groundwater withdrawals through augmented replenishments from extreme rainfall and 'managed aquifer recharge' practices.
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Climate
| 2,020 |
May 4, 2021
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https://www.sciencedaily.com/releases/2021/05/210504112643.htm
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Confirmation of an auroral phenomenon
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A new auroral phenomenon discovered by Finnish researchers a year ago is probably caused by areas of increased oxygen atom density occurring in an atmospheric wave channel. The speculative explanation offered by the researchers gained support from a new study.
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Observations made by University of Helsinki researchers increased the validity of a speculative mechanism according to which a type of aurora borealis named 'dunes' is born. In the new study, photographs of the phenomenon taken by an international group of hobbyists in Finland, Norway and Scotland were compared to concurrent satellite data.The rare type of aurora borealis was seen in the sky on 20 January 2016 and recorded in photos taken by several hobbyists."The dunes were seen for almost four hours in a very extensive area, with the pattern extending roughly 1,500 kilometres from east to west and some 400 kilometres from north to south," says Postdoctoral Researcher Maxime Grandin from the Centre of Excellence in Research of Sustainable Space coordinated by the University of Helsinki.Useful photographic and video material was collected in close cooperation with Finnish aurora borealis hobbyists, utilising both the internet and social media. Among other things, a time lapse video shot on the night in question by a Scottish hobbyist was found. The video was used to estimate the dunes' propagation speed at over 200 m/s.The study was published in the Northern Lights are born when charged particles ejected by the Sun, such as electrons, collide with oxygen atoms and nitrogen molecules in Earth's atmosphere. The collision momentarily excites the atmospheric species, and this excitation is released in the form of light.New types of aurora borealis are rarely discovered. The identification of this new auroral form last year was the result of an exceptional collaboration between hobbyists who provided observations and researchers who started looking into the matter.The new auroral form named dunes is relatively rare, and its presumed origin is peculiar."The differences in brightness within the dune waves appear to be caused by the increased density of atmospheric oxygen atoms," says Professor Minna Palmroth.A year ago, researchers at the Centre of Excellence in Research of Sustainable Space concluded that the dune-like shape of the new auroral emission type could be caused by concentrations of atmospheric oxygen. This increased density of oxygen atoms is assumed to be brought about by an atmospheric wave known as a mesospheric bore travelling horizontally within a wave guide established in the upper atmosphere.This rare wave guide is created in between the boundary of the atmospheric layer known as the mesosphere, which is called the mesopause, and an inversion layer that is intermittently formed below the mesopause. This enables waves of a certain wavelength to travel long distances through the channel without subsiding.The electron precipitation and temperature observations made in the recently published study supported the interpretations of the dunes' origins made a year earlier. An independent observation was made of the wave channel appearing in the area of the dunes, but there are no observation data for the mesospheric bore itself yet."Next, we will be looking for observations of the mesospheric bore in the wave guide," Maxime Grandin says.According to the observation data, electron precipitation occurred in the area where the dunes appeared on 20 January 2016. Therefore, it is highly likely that electrons having the appropriate energy to bring about auroral emissions at an altitude of roughly 100 kilometres were involved. The observations were collected by the SSUSI instrument carried by a DMSP satellite, which measures, among other things, electron precipitation.On the night in question, there was an exceptionally strong temperature inversion layer in the mesosphere, or a barrier generated by layers of air with different temperatures. The inversion layer associated with the origins of the wave channel was measured with the SABER instrument carried by the TIMED satellite. The observation supports the hypothesis according to which the auroral form originates in areas of increased oxygen density occurring in the upper atmosphere wave guide.Viideo:
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Environment
| 2,021 |
May 4, 2021
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https://www.sciencedaily.com/releases/2021/05/210504112629.htm
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New 'key-hole surgery' technique to extract metals from the Earth
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Scientists have developed a new "key-hole surgery" technique to extract metals from the earth -- which could revolutionise the future of metal mining
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A team of international researchers, including Dr Rich Crane from the Camborne School of Mines, University of Exeter, have developed a new method to extract metals, such as copper, from their parent ore body.The research team have provided a proof of concept for the application of an electric field to control the movement of an acid within a low permeability copper-bearing ore deposit to selectively dissolve and recover the metal in situ.This is in contrast to the conventional approach for the mining of such deposits where the material must be physically excavated, which requires removal of both overburden and any impurities within the ore (known as gangue material).The researchers believe the new technique has the potential to transform the mining industry, because it has the capability to dissolve metals from a wide range of ore deposits that were previously considered inaccessible.Furthermore, due to the non-invasive nature of the extraction, the research team are hopeful that the study will help usher in a more sustainable future for the industry.This is urgently required now in order to provide the plethora of metals required to deliver green technology, such as renewable energy infrastructure and electrified vehicles, whilst limiting any potential environmental damage associated with the mining of such vitally important metals.The study was recently published in Dr Rich Crane from the Camborne School of Mines, University of Exeter, and co-author of the study, said: "This new approach, analogous to "key-hole surgery," has the potential to provide a more sustainable future for the mining industry, by enabling the recovery of metals, such as copper, which are urgently needed for our global transition to a new Green Economy, whilst avoiding unwanted environmental disturbance and energy consumption."The central principle behind most modern mining techniques has not fundamentally changed since their original conception, which marked the beginning of the Bronze Age: metals are recovered from the subsurface via physical excavation, i.e., the construction of tunnels to gain access to the deposits, or by creating "open cast" mines.This technique demands large volumes of surface soil, overburden and gangue material to also be excavated, which can contain millions of tonnes of material -- and can also lead to habitat destruction.In this new publication, experts from the University of Western Australia, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), the Technical University of Denmark and the University of Exeter, have demonstrated that a targeted electric field can be used to dissolve and then recover copper in situ from the ore -- avoiding any requirement to physically excavate the material.This new technology comprises the construction (drilling) of electrodes directly into an ore body. An electric current is then applied which can result in the transport of electrically charged metal ions, such as copper, through the rock via a process called electromigration.The research team have now provided a Proof of Concept for this new technology at laboratory scale, which has also been verified using computer modelling. They are confident that the idea will work beyond the laboratory-scale.
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Environment
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