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June 14, 2019
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https://www.sciencedaily.com/releases/2019/06/190614163158.htm
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No direct link between North Atlantic currents, sea level along New England coast
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A new study by the Woods Hole Oceanographic Institution (WHOI) clarifies what influence major currents in the North Atlantic have on sea level along the northeastern United States. The study, published June 13 in the journal
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"Scientists had previously noticed that if the AMOC is stronger in a given season or year, sea levels in the northeast U.S. go down. If the AMOC weakens, average sea levels rise considerably," says Chris Piecuch, a physical oceanographer at WHOI and lead author on the paper. "During the winter of 2009-2010, for example, we saw the AMOC weaken by 30 percent. At the same time, sea level in our region rose by six inches. That doesn't sound like a lot, but a half-foot of sea level rise, held for months, can have serious coastal impacts.""But, it's been unclear whether those two things -- coastal sea level and the AMOC -- are linked by cause and effect," adds Piecuch. Although the study confirmed that AMOC intensity and sea level seem to change at the same time, it found that neither directly causes changes in the behavior of the other. Instead, both seem to be controlled simultaneously by variability in major weather patterns over the North Atlantic, such as the North Atlantic Oscillation (NAO)."Changes in the NAO alter both AMOC and sea level separately," says Piecuch. "As the NAO changes, it affects the trade winds, which blow from the east across the tropical Atlantic. When the NAO is high, the trade winds are stronger than normal, which in turn strengthens AMOC. But at the same time, the westerly winds over New England are also stronger than usual. Together with unusually high air pressure on the northeast coast, this lowers the average sea level. It's wind and pressure that are driving both phenomena."According to Piecuch, a study like this was not even possible until recently. For the past few decades, satellite imagery has given scientists a record of movement at the ocean's surface, but has been unable to detect currents below the surface. Starting in 2004, however, an international team of scientists began maintaining a chain of instruments that stretch across the Atlantic between Florida and Morocco. The instruments, which are collectively called the RAPID array, hold a variety of sensors that measure currents, salinity, and temperature. "RAPID doesn't resolve the details of every individual current along the way, but it does give us the sum total of the ocean's behavior, which is what the AMOC represents," Piecuch notes.These findings are particularly important for residents along the northeast coast of the U.S., he adds. Existing climate models suggest sea levels will rise globally in the next century due to climate change, but that sea level rise on the New England coast will be greater than the global average. Scientists have traditionally assumed that the heighted future sea level rise in the northeast U.S. is inextricably tied to a weakening of the AMOC, which the climate models also predict. But, given the study's findings, that assumption might need to be revisited, Piecuch says. "The problem right now is that we only have about 13 years of AMOC data to work with. To get a better sense of how these two things relate to one another in the long term, we'll need to wait for a longer stretch of observational records to become available," he says.Also collaborating on the study were Glen G. Gawarkiewicz and Jiayan Yang of WHOI; Sönke Dangendorf of Universität Siegen in Germany; and Christopher M. Little and Rui M. Ponte of Atmospheric and Environmental Research, Inc.The work was supported by National Science Foundation awards OCE-1558966, OCE-1834739, and OCE-1805029; NASA contract NNH16CT01C; and the J. Lamar Worzel Assistant Scientist Fund and the Penzance Endowed Fund in Support of Assistant Scientists at the Woods Hole Oceanographic Institution.
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June 13, 2019
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https://www.sciencedaily.com/releases/2019/06/190613095204.htm
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Warming waters in western tropical Pacific may affect West Antarctic Ice Sheet
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Warming waters in the western tropical Pacific Ocean have significantly increased thunderstorms and rainfall, which may affect the stability of the West Antarctic Ice Sheet and global sea-level rise, according to a Rutgers University-New Brunswick study.
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Since the mid-1990s, West Antarctica -- a massive ice sheet that sits on land -- has been melting and contributing to global sea-level rise. That melting has accelerated this century. Wind and weather patterns play a crucial role in governing the melting: Winds push warm ocean water toward the ice sheet and melt it from below, at the same time as winds bring warm air over the ice sheet surface and melt it from above.The study, in the journal "With so much at stake -- in coastal communities around the globe, including in New Jersey -- it is very important to understand the drivers of weather variability in West Antarctica," said Kyle Clem, a former post-doc who led the research at Rutgers-New Brunswick and is now at Victoria University of Wellington in New Zealand. "Knowing how all regions of the tropics influence West Antarctica, both independently and collectively, will help us understand past climate variability there and perhaps help us predict the future state of the ice sheet and its potential contribution to global sea-level rise."Rutgers researchers studied how warming ocean temperatures in the western tropical Pacific influence weather patterns around West Antarctica. This century, the Antarctic Peninsula and interior West Antarctica have been cooling while the Ross Ice Shelf has been warming -- a reversal of what happened in the second half of the 20th century. From the 1950s to the 1990s, the Antarctic Peninsula and interior West Antarctica were the most rapidly warming regions on the planet, and the Ross Ice Shelf was cooling.The temperature trends flipped at the start of this century. Coinciding with the flip in West Antarctic temperature trends, ocean temperatures in the western tropical Pacific began warming rapidly. Using a climate model, the researchers found that warming ocean temperatures in the western tropical Pacific have resulted in a significant increase in thunderstorm activity, rainfall and convection in the South Pacific Convergence Zone. Convection in the atmosphere is when heat and moisture move up or down.A rainfall increase in the zone results in cold southerly winds over the Antarctic Peninsula and warm northerly winds over the Ross Ice Shelf, consistent with the recent cooling and warming in those respective regions. So the West Antarctic climate, although isolated from much of the planet, is profoundly influenced by the tropics. The findings may help scientists interpret the past West Antarctic climate as recorded in ice cores.Study co-authors include Benjamin R. Lintner, an associate professor in the Department of Environmental Sciences; Anthony J. Broccoli, a professor who chairs that department; and James R. Miller, a professor in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences.
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June 12, 2019
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https://www.sciencedaily.com/releases/2019/06/190612084334.htm
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Climate change benefits for giant petrels
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Giant petrels will be "temporary" winners from the effects of climate change in the Antarctic region -- but males and females will benefit in very different ways, a new study shows.
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The study, by experts from the University of Exeter and the British Antarctic Survey (BAS), is one the first to analyse how different sexes of the same species could be affected by changing conditions through global warming.The research shows that giant petrels -- known colloquially as "stinkers" -- will benefit from an increased number of warm weather anomalies in the region, while changes to wind patterns across the Antarctic and the southwest Atlantic will also improve their ability to forage at sea.However, the research reveals that the benefits are different for the male of the species, compared to females.It shows that the males -- as the larger and heavier sex -- would benefit more by dominating access to carrion on land and by traveling much less far from the colony when foraging at sea.Females, on the other hand, are likely to benefit from stronger winds which will help them fly and forage at sea with less effort, and from retreating sea ice increasing the extension of open waters suitable for foraging.Crucially, however the study also suggests that any increase in longline fishing (and resulting mortality on fishing gear -- termed bycatch) could harm their survival.Few studies have examined how different sexes of a species could be affected by changing conditions, and the researchers say this means the impacts could be underestimated if sex-specific effects are not included."It is really difficult -- but really important -- to measure how the sexes of a species will respond to environmental changes, especially in species with strong sexual size dimorphism, like the giant petrels," said lead author Dr Dimas Gianuca, of the University of Exeter and BAS. "Petrels are going to do relatively well due to the changes we expect to see in this region. The increased winds and other changes in the environment will be good for them. However, any future increase in longline fishing -- which may well result in a greater risk of bycatch -- is likely to impair the survival of females, which forage further north than males and, consequently interact more with poorly managed longline fishing in subtropical waters."The study analysed 15 years of monitoring data on giant petrel survival and breeding collected by BAS at Bird Island, South Georgia, and projected the likely consequences of future environmental change and fishing.Though petrels appear to be climate change "winners" in the coming decades, the researchers warn this could be temporary."Although warm conditions may benefit giant petrels, in the long term, persistent warm anomalies can lead to broader ecosystem disruptions in Antarctic food webs, and potentially further reduction in krill stocks. This would lead to further population declines of South Georgia Antarctic fur seals and other species on which male giant petrels depend for food during the breeding season, therefore it will be bad for petrels too," said Dr Richard Sherley, of the University of Exeter.Dimas Gianuca's PhD scholarship was funded by a Brazilian government scheme called Science Without Borders. Funding for BAS's work came from the Natural Environment Research Council (NERC).
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June 11, 2019
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https://www.sciencedaily.com/releases/2019/06/190611081857.htm
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Skinny cod and grey seal reveals troubling changes to food web in the Baltic Sea
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"It is important that you understand how the food web works when managing a fishery. It is not enough to manage how the fish and fisheries are changing. The availability and quality of food is at least as important," says Lena Bergström, researcher at the Department of Aquatic Resources at the Swedish Agricultural University.
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In a collaboration between several universities, the authors of the study examined how the health and abundance of certain species has changed over two decades in the Bothnian Sea and the Baltic Proper. They investigated seal, cod, herring, sprat, isopods, amphipods and zooplankton; species that all occur at different levels in the Baltic Sea food web. The system is complex and several species can be both predators and prey. For example, herring eats zooplankton and some bottom fauna while the herring itself is eaten by cod and seal.The study primarily shows that there are links between the health of both cod and seal with the availability of bottom-living animals. Regarding the seals, the connection is indirect through that the herring it eats is influenced by the availability of the bottom-living animals. In both cases, there is a link to climate change and eutrophication:"Oxygen levels in Baltic Sea have reduced since the 1990s, in big part due to eutrophication, creating vast oxygen-free areas. This leads to less living space for the bottom-living prey animals. This has, among other things, led to the fact that the isopods have become fewer and smaller, making them a poorer food choice for cod," says Agnes Karlsson, lead author and researcher at the Department of Ecology, Environment and Plant Sciences (DEEP) at Stockholm University.The fat content and the mean weight of herring in the Bothnian Sea have, according to the study, recently improved because of the supply of the bottom-living crustacean, the amphipod, has increased."However, the upturn is relative, because the amphipod in the Bothnian Sea collapsed in the early 2000s and what we now see are signs of a recovery," says Agnes Karlsson.The bottom-living crustaceans were almost eliminated after a period of extremely heavy rain that changed the water quality of the Bothnian Sea."With climate change it is likely that we will see similar extreme events more frequently in the future. If activities that lead to eutrophication are not reduced, oxygen shortage in the Baltic Sea will likely continue, leading to further reductions in the numbers of bottom-living animals. This can have far reaching effects for the economy, with reference to the fish species that are important commercially. To manage a fishery, we must also manage the environment and the food web," says Lena Bergström.
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June 10, 2019
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https://www.sciencedaily.com/releases/2019/06/190610111522.htm
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Mysterious holes in Antarctic sea ice explained by years of robotic data
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The winter ice on the surface of Antarctica's Weddell Sea occasionally forms an enormous hole. A hole that appeared in 2016 and 2017 drew intense curiosity from scientists and reporters. Though even bigger gaps had formed decades before, this was the first time oceanographers had a chance to truly monitor the unexpected gap in Antarctic winter sea ice.
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A new study led by the University of Washington combines satellite images of the sea ice cover, robotic drifters and even seals outfitted with sensors to better understand the phenomenon. The research explores why this hole appears in only some years, and what role it could play in the larger ocean circulation.The study was published June 10 in the journal "We thought this large hole in the sea ice -- known as a polynya -- was something that was rare, maybe a process that had gone extinct. But the events in 2016 and 2017 forced us to reevaluate that," said lead author Ethan Campbell, a UW doctoral student in oceanography. "Observations show that the recent polynyas opened from a combination of factors -- one being the unusual ocean conditions, and the other being a series of very intense storms that swirled over the Weddell Sea with almost hurricane-force winds."A "polynya," a Russian word that roughly means "hole in the ice," can form near shore as wind pushes the ice around. But it can also appear far from the coast and stick around for weeks to months, where it acts as an oasis for penguins, whales and seals to pop up and breathe.This particular spot far from the Antarctic coast often has small openings and has seen large polynyas before. The biggest known polynyas at that location were in 1974, 1975 and 1976, just after the first satellites were launched, when an area the size of New Zealand remained ice-free through three consecutive Antarctic winters despite air temperatures far below freezing.Campbell joined the UW as a graduate student in 2016 to better understand this mysterious phenomenon. In a stroke of scientific luck, a big one appeared for the first time in decades. A NASA satellite image in August 2016 drew public attention to a 33,000-square-kilometer (13,000-square-mile) gap that appeared for three weeks. An even bigger gap, of 50,000 square kilometers (19,000 square miles) appeared in September and October of 2017.The Southern Ocean is thought to play a key role in global ocean currents and carbon cycles, but its behavior is poorly understood. It hosts some of the fiercest storms on the planet, with winds whipping uninterrupted around the continent in the 24-hour darkness of polar winter. The new study used observations from the Southern Ocean Carbon and Climate Observations and Modeling project, or SOCCOM, which puts out instruments that drift with the currents to monitor Antarctic conditions.The study also used data from the long-running Argo ocean observing program, elephant seals that beam data back to shore, weather stations and decades of satellite images."This study shows that this polynya is actually caused by a number of factors that all have to line up for it to happen," said co-author Stephen Riser, a UW professor of oceanography. "In any given year you could have several of these things happen, but unless you get them all, then you don't get a polynya."The study shows that when winds surrounding Antarctica draw closer to shore, they promote stronger upward mixing in the eastern Weddell Sea. In that region, an underwater mountain known as Maud Rise forces dense seawater around it and leaves a spinning vortex above. Two SOCCOM instruments were trapped in the vortex above Maud Rise and recorded years of observations there.Analysis shows that when the surface ocean is especially salty, as seen throughout 2016, strong winter storms can set off an overturning circulation. Warmer, saltier water from the depths gets churned up to the surface, where air chills it and makes it denser than the water below. As that water sinks, relatively warmer deep water of about 1 degree Celsius (34 F) replaces it, creating a feedback loop where ice can't reform.Under climate change, fresh water from melting glaciers and other sources will make the Southern Ocean's surface layer less dense, which might mean fewer polynyas in the future. But the new study questions that assumption. Many models show that the winds circling Antarctica will become stronger and draw closer to the coast -- the new paper suggests this would encourage more polynyas to form, not fewer.These are the first observations to prove that even a smaller polynya like the one in 2016 moves water from the surface all the way to the deep ocean."Essentially it's a flipping over of the entire ocean, rather than an injection of surface water on a one-way trip from the surface to the deep," said co-author Earle Wilson, who recently completed his doctorate in oceanography at the UW.One way that a surface polynya matters for the climate is for the deepest water in the oceans, known as Antarctic Bottom Water. This cold, dense water lurks below all the other water. Where and how it's created affects its characteristics, and would have ripple effects on other major ocean currents."Right now people think most of the bottom water is forming on the Antarctic shelf, but these big offshore polynyas might have been more common in the past," Riser said. "We need to improve our models so we can study this process, which could have larger-scale climate implications."Large and long-lasting polynyas can also affect the atmosphere, because deep water contains carbon from lifeforms that have sunk over centuries and dissolved on their way down. Once this water reaches the surface that carbon could be released."This deep reservoir of carbon has been locked away for hundreds of years, and in a polynya it might get ventilated at the surface through this really violent mixing," Campbell said. "A large carbon outgassing event could really whack the climate system if it happened multiple years in a row."Other co-authors on the paper are Kent Moore at the University of Toronto, who was the 2016-17 Canada Fulbright Visiting Chair in Arctic Studies at the UW; Casey Brayton at the University of South Carolina; and Lynne Talley and Matthew Mazloff from Scripps Institution of Oceanography at the University of California, San Diego. SOCCOM is funded by the National Science Foundation. Campbell was supported by the U.S. Department of Defense through the National Defense Science & Engineering Graduate Fellowship program. Additional funding is from the NSF, the National Oceanic and Atmospheric Administration, the University of Washington and Scripps Institution of Oceanography.
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June 5, 2019
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https://www.sciencedaily.com/releases/2019/06/190605100318.htm
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Honey bee colonies down by 16 percent
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The number of honey bee colonies fell by 16% in the winter of 2017-18, according to an international study led by the University of Strathclyde.
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The survey of 25,363 beekeepers in 36 countries found that, out of 544,879 colonies being managed at the start of winter, 89124 were lost, through a combination of circumstances including various effects of weather conditions, unsolvable problems with a colony's queen, and natural disaster.Portugal, Northern Ireland, Italy and England experienced losses above 25%, while Belarus, Israel and Serbia were among those with loss rates below 10%. There were also significant regional variations within some countries, including Germany, Sweden and Greece.The total loss rate was down from 20.9% in 2016-17 but was still higher than the 2015-16 figure of 12.0%. The total loss rate for Scotland increased over these three years, from 18.0% to 20.4% to 23.7%.In a departure from previous findings, beekeepers who moved their colonies in the foraging season, to access other forage or for pollination, faced fewer losses than those who kept their bees in the same place. Smaller-scale beekeeping operations also had higher losses than larger ventures.The study, based on voluntarily submitted information, covered 33 countries in Europe -- including the four nations of the UK -- along with Algeria, Israel and Mexico.It has been published in the Dr Alison Gray, a Lecturer in Strathclyde's Department of Mathematics & Statistics, led the study. She said: "Loss of honey bee colonies is a highly complex issue. It tends to be influenced less by overall climate than by specific weather patterns or a natural disaster affecting the colony. We observe colonies in winter but what happens to the bees then can be partly determined by the conditions of the previous summer."Many are also lost when there are problems with a colony's queen -- for example, if she goes missing or is not laying the fertilised eggs which go on to become worker bees. Most colonies are also under attack from varroa mites, a parasitic mite."The impact of beekeepers migrating their colonies would be expected to be partly dependent on the distance travelled and the reasons for migration; this would be worth further investigation."The study had a focus on sources of forage, plants which bees visit to collect nectar and pollen, in six categories: orchards; oilseed rape; maize; sunflower; heather and autumn forage crops. These were potentially useful food sources for bees, which could help to build up a colony, but, by extending the active and brood-rearing season of the bees, forage which was available late in the season could also extend the reproductive cycle for varroa mites, weakening the bee colonies and making winter losses more likely.
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May 31, 2019
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https://www.sciencedaily.com/releases/2019/05/190531135815.htm
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Community impacts from extreme weather shape climate beliefs
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Recent studies have suggested that people who experience the impacts of hurricanes, catastrophic flooding or other severe weather events are more likely to believe in, and be concerned about, climate change in the wake of the disaster.
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But a new study by researchers at Duke University and the University of Colorado Denver (UCD) finds that not all severe weather impacts have the same effect."How our community or neighborhood fares -- the damages it suffers -- may have a stronger and more lasting effect on our climate beliefs than individual impacts do," said Elizabeth A. Albright, assistant professor of the practice of environmental science and policy methods at Duke's Nicholas School of the Environment."We found that damage at the zip-code level as measured by FEMA was positively associated with stronger climate change beliefs even three or four years after the extreme flooding event our study examined," Albright said.People who perceived that damage had occurred at such a broad scale were more likely to believe that climate change is a problem and is causing harm, she explained. They were also more likely to perceive a greater risk of future flooding in their community.In contrast, individual losses such as damage to one's own house appeared to have a negligible long-term impact on climate change beliefs and perceptions of future risks."These findings speak to the power of collective experiences and suggest that how the impacts from extreme weather are conceptualized, measured and shared matters greatly in terms of influencing individual beliefs," said Deserai Crow, associate professor of public affairs at UCD.Albright and Crow published their peer-reviewed paper May 31 in the journal To conduct their study, in 2016 and 2017 they surveyed residents of six Colorado communities -- Boulder, Longmont, Lyons, Estes Park, Loveland and Evans -- that had suffered devastating flooding after days of intense rainfall dropped nearly a year's worth of precipitation in mountains upstream from them in September 2013.The surveys queried residents about their climate change beliefs, their perception of the extent of damage caused by the 2013 flooding, and their perception of future flood risks in their neighborhood. It also asked for personal information, such as political affiliation.In each community, 150 surveys were sent to randomly selected homes in areas that had been inundated by the flood and 350 surveys were sent to randomly selected homes in neighborhoods that had been spared. A total of 903 surveys were completed and returned, for an overall response rate of about 17%."As expected, we found that political affiliation was related to the extent to which flood experience affected a person's climate beliefs," said Crow, who is also an affiliate with the Center for Science & Technology Policy Research at the University of Colorado Boulder.This partisan divide did not extend to perceptions of future floods risks, she noted. Republicans and Democrats perceived similar levels of risk, regardless of whether or not they attributed it to human-caused climate change."It's important that we understand these differences and commonalities if we want to build back better and more resiliently after a severe weather disaster," Albright said. "As climate change plays out and we see more frequent extreme weather and floods, how communities respond to those events may predict how resilient they become and how they will recover."Funding for the study came from the National Science Foundation (grants #1461565 and #1461923).
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May 20, 2019
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https://www.sciencedaily.com/releases/2019/05/190520081914.htm
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Can a hands-on model help forest stakeholders fight tree disease?
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When a new, more aggressive strain of the pathogen that causes sudden oak death turned up in Oregon, scientists and stakeholders banded together to try to protect susceptible trees and the region's valuable timber industry.
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Sudden oak death is a serious threat. Since 1994, the disease has killed millions of trees in California and Oregon. If the disease spreads from an isolated outbreak in Curry County, Oregon, to neighboring Coos County, the impact could be severe: a 15% reduction in timber harvest, loss of 1,200 jobs and about $58 million in lost wages, according to an Oregon Department of Forestry report.Researchers with North Carolina State University's Center for Geospatial Analytics reached out to help in Oregon, offering Tangible Landscape, an interactive model that allows people of all skill levels to control complex simulation models with their hands and collaboratively explore scenarios of management decisions.While predictive models can provide useful forecasts about where the pathogen may go, they can be tough to work with, requiring coding or technical software experience, says Devon Gaydos, lead author of an article in "The Tangible Landscape system makes it a lot easier because people can interact with the model by touch instead of through the code or the computer," Gaydos says. "People can add objects to a 3D model of the landscape to represent different types of management, and then with the click of a button we see how that action may affect the disease's spread within a few moments."The model also allows participants to factor in budgets for disease management to try out different approaches to stop its spread, both on a large and small scale, Gaydos says."You can think of our disease spread model like a weather forecast: Knowing what the weather may look like this afternoon can help you decide if you want to bring an umbrella to work," she explains. "Similarly, knowing how the pathogen may spread over the next year can help people gather resources, figure out which areas to target for surveillance or management, and request funding."Researchers took a participatory modeling approach because the disease could affect many stakeholders in Oregon -- private landowners, timber producers, U.S. Forest Service managers, tribal groups that consider tanoak trees sacred, and thousands of local residents, including those employed in the timber industry. They began by working with a dozen local and regional experts, in the spirit of learning from each other."The idea of co-creating models with stakeholders is that by involving the people who are most affected, you're going to get better data as a scientist because they have a lot of information about local dynamics and on-the-ground management that you may not know," Gaydos says."It's all about working together as partners to frame questions and problems, improve models and decide how to use those results for sustainable solutions," adds co-author Ross Meentemeyer, NC State Forestry and Environmental Resources professor and director of the Center for Geospatial Analytics.In this case, the team found out that some of the data used in the model needed to be more accurate at a fine scale -- a problem participants could help with. In addition, the model needed to show the impact of decisions at more frequent intervals to capture the complexity of field operations.The team also learned that collective action is paramount. Meentemeyer notes that "just a few uncooperative landowners 'opting out' of management could allow the pathogen to escape quarantine and the put the region at huge economic risk."After making adjustments, researchers plan to use an updated version of Tangible Landscape with a larger group of stakeholders in Oregon, as well as pursuing new research."More and more stakeholders are becoming interested in using the model, and the Oregon Department of Forestry wants to use it in an economic analysis of the situation and to test different management scenarios for the future," Gaydos says."We are excited to collaborate with more teams and apply our modeling approach to forecast and control emerging infectious diseases of other plant, animal and human populations," Meentemeyer says.
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May 16, 2019
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https://www.sciencedaily.com/releases/2019/05/190516114601.htm
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Nearly a quarter of West Antarctic ice is now unstable
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By combining 25 years of European Space Agency satellite altimeter measurements and a model of the regional climate, the UK Centre for Polar Observation and Modelling (CPOM) have tracked changes in snow and ice cover across the continent.
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A team of researchers, led by Professor Andy Shepherd from the University of Leeds, found that Antarctica's ice sheet has thinned by up to 122 metres in places, with the most rapid changes occurring in West Antarctica where ocean melting has triggered glacier imbalance.This means that the affected glaciers are unstable as they are losing more mass through melting and iceberg calving than they are gaining through snowfall.The team found that the pattern of glacier thinning has not been static. Since 1992, the thinning has spread across 24% of West Antarctica and over the majority of its largest ice streams -- the Pine Island and Thwaites Glaciers -- which are now losing ice five times faster than they were at the start of the survey.The study, published today in Together, these measurements allow changes in the ice sheet height to be separated into those due to weather patterns, such as less snowfall, and those due to longer term changes in climate, such as increasing ocean temperatures that eat away ice.Lead author and CPOM Director Professor Andy Shepherd explained: "In parts of Antarctica the ice sheet has thinned by extraordinary amounts, and so we set out to show how much was due to changes in climate and how much was due to weather."To do this, the team compared the measured surface height change to the simulated changes in snowfall, and where the discrepancy was greater they attributed its origin to glacier imbalance.They found that fluctuations in snowfall tend to drive small changes in height over large areas for a few years at a time, but the most pronounced changes in ice thickness are signals of glacier imbalance that have persisted for decades.Professor Shepherd added: "Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record. We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica's most vulnerable glaciers, and their losses are driving up sea levels around the planet."Altogether, ice losses from East and West Antarctica have contributed 4.6 mm to global sea level rise since 1992."Dr Marcus Engdahl of the European Space Agency, a co-author of the study, added: "This is an important demonstration of how satellite missions can help us to understand how our planet is changing. The polar regions are hostile environments and are extremely difficult to access from the ground. Because of this, the view from space is an essential tool for tracking the effects of climate change."
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Weather
| 2,019 |
May 6, 2019
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https://www.sciencedaily.com/releases/2019/05/190506111441.htm
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'Impossible' research produces 400-year El Niño record, revealing startling changes
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Australian scientists have developed an innovative method using cores drilled from coral to produce a world first 400-year long seasonal record of El Niño events, a record that many in the field had described as impossible to extract.
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The record published today in This understanding of El Niño events is vital because they produce extreme weather across the globe with particularly profound effects on precipitation and temperature extremes in Australia, South East Asia and the Americas.The 400-year record revealed a clear change in El Niño types, with an increase of Central Pacific El Niño activity in the late 20th Century and suggested future changes to the strength of Eastern Pacific El Niños."We are seeing more El Niños forming in the central Pacific Ocean in recent decades, which is unusual across the past 400 years," said lead author Dr Mandy Freund."There are even some early hints that the much stronger Eastern Pacific El Niños, like those that occurred in 1997/98 and 2015/16 may be growing in intensity."This extraordinary result was teased out of information about past climate from coral cores spanning the Pacific Ocean, as part of Dr Freund's PhD research at the University of Melbourne and the Centre of Excellence for Climate Extremes. It was made possible because coral cores -- like tree rings -- have centuries-long growth patterns and contain isotopes that can tell us a lot about the climate of the past. However, until now, they had not been used to detect the different types of El Niño events.This meant El Niño researchers were constrained by what they could say about El Niño behaviour because the instrumental record was too short and it was hard to judge whether recent decadal changes were exceptional."By understanding the past, we are better equipped to understand the future, especially in the context of climate change," said Dr Freund."Prior to this research, we did not know how frequently different types of El Niño occurred in past centuries. Now we do," said co-author from the Centre of Excellence for Climate Extremes Dr Ben Henley.The key to unlocking the El Niño record was the understanding that coral records contained enough information to identify seasonal changes in the tropical Pacific Ocean. However, using coral records to reconstruct El Niño history at a seasonal timescale had never been done before and many people working in the field considered it impossible.It was only after Dr Freund took her innovative approach to a team of climate scientists and coral experts: Dr Ben Henley, Prof David Karoly, Assoc Prof Helen Mcgregor, Assoc Prof Nerilie Abram, and Dr Dietmar Dommenget that they were able to proceed with the idea.While the approach was considered challenging, leading Australian experts on past corals, Dr Mcgregor and Assoc Prof Abram, said that, while the approach might be unconventional, it was worth a shot.After carefully refining the technique to reconstruct the signature of El Niño in space and time using new machine learning techniques, the scientists were able to compare recent coral results with the instrumental record. Dr Freund found a strong agreement between the coral cores and recorded events. This confirmation allowed the team to extend the record back in time.Dr Freund and her team found there has been an unprecedented increase in the number of El Niños forming in the Central Pacific over the past 30 years, compared to all 30 year periods in the past 400 years.At the same time, the stronger Eastern Pacific El Niños were the most intense El Niño events ever recorded, according to both the 100-year long instrumental record and the 400-year long coral record.As a result, Australian researchers have produced a world-first seasonal El Niño record extending 400 years and a new methodology that will likely be the basis for future climate research.It took three years of hard work to achieve the result and now Dr Freund and her team are excited to see how this work can be built upon."The El Niño phenomenon is one of the most important features of global climate, and changes to its behaviour have very serious implications for weather patterns and extreme events around the world," said Dr Henley.And that centuries-long record opens a door not just to past changes but changes to El Niños in the future as well."This gives us an opportunity to more accurately explore how global warming may change El Niños and what this means for future weather and climate extremes," said Dr Henley."Having a better understanding of how different types of El Niños have affected us in the past and present, will mean we are more able to model, predict and plan for future El Niños and their wide-ranging impacts," said Dr Freund.
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Weather
| 2,019 |
May 6, 2019
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https://www.sciencedaily.com/releases/2019/05/190506083952.htm
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The winter weather window that is costing rapeseed growers millions
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UK rapeseed growers are losing up to a quarter of their crop yield each year because of temperature rises during an early-winter weather window.
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This figure emerged in new research by the John Innes Centre which identifies a a critical period from late November to the Winter Solstice, December 21 or 22, where temperature has a strong link to yields.The research, which appears in the journal Based on analysis of climate and yield data, the team calculate that temperature variation during this critical time window can lead to losses of up to £160 million in the UK rapeseed harvest -- about 25 percent of the total value.Oilseed Rape, in common with many other winter crops, requires a prolonged period of chilling, known as vernalisation, for the plants to flower and set seed. The effect of climate fluctuations on this process is the focus of considerable interest among researchers and breeders looking to safeguard and stabilise yields.Professor Steven Penfield a lead author on the paper says: "Wide variations in oilseed rape yield is a major problem for farmers so we looked at links to temperature to see whether rising temperatures could have an impact on yields. We had observed there was an effect; what is surprising is the magnitude of the effect we found.""The study shows that chilling of the crop in winter is really important for the development of a high yield. But it's not just winter in general, it's a specific time from late November and through December. Our data showed that even if its colder in January and February, it doesn't have the same effect on yield."The team analysed data stretching back 25 years from DEFRA and Agriculture and Horticulture Development Board (AHDB) trials to model how temperatures were affecting productivity."If you ask farmers why they don't grow more rapeseed, they usually say it's too unreliable," says Professor Penfield. "The data in our study clearly shows temperature is having a direct effect on UK agriculture productivity."In the UK there have been improvements in Oilseed Rape yields in recent years. But this has not been accompanied by increases in yield stability with year on year variation accounting for up to 30% of crop value. Until now the drivers of this instability have been unclear.Climatically winter weather in the UK is subject to temperature volatility due to a phenomenon known as the North Atlantic Oscillation. Through fluctuations of atmospheric pressure this can bring warmer, wetter westerly winds or chilly easterlies which bring colder, drier weather to the UK.In the study the researchers ranked oilseed rape varieties according to the stability of their annual yield. Further genetic analysis showed that the trait of yield stability is not correlated with that of yield."This means it should be possible to breed for yield stability and high yields together without having to sacrifice one for the other," says Professor Penfield.The study, in establishing a clear link between temperature and productivity raises the hope that future rapeseed crops can be bred so that they are less temperature-sensitive, offering breeders the prospect of more stable and productive yields.
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Weather
| 2,019 |
May 6, 2019
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https://www.sciencedaily.com/releases/2019/05/190506093629.htm
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Banana disease boosted by climate change
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Climate change has raised the risk of a fungal disease that ravages banana crops, new research shows.
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Black Sigatoka disease emerged from Asia in the late 20th Century and has recently completed its invasion of banana-growing areas in Latin America and the Caribbean.The new study, by the University of Exeter, says changes to moisture and temperature conditions have increased the risk of Black Sigatoka by more than 44% in these areas since the 1960s.International trade and increased banana production have also aided the spread of Black Sigatoka, which can reduce the fruit produced by infected plants by up to 80%."Black Sigatoka is caused by a fungus ("This research shows that climate change has made temperatures better for spore germination and growth, and made crop canopies wetter, raising the risk of Black Sigatoka infection in many banana-growing areas of Latin America."Despite the overall rise in the risk of Black Sigatoka in the areas we examined, drier conditions in some parts of Mexico and Central America have reduced infection risk."The study combined experimental data on Black Sigatoka infections with detailed climate information over the past 60 years.Black Sigatoka, which is virulent against a wide range of banana plants, was first reported in Honduras in 1972.It spread throughout the region to reach Brazil in 1998 and the Caribbean islands of Martinique, St Lucia and St Vincent and the Grenadines in the late 2000s.The disease now occurs as far north as Florida."While fungus is likely to have been introduced to Honduras on plants imported from Asia for breeding research, our models indicate that climate change over the past 60 years has exacerbated its impact," said Dr Bebber.The The study did not attempt to predict the potential effects of future climate on the spread and impact of Black Sigatoka. Other research suggests drying trends could reduce disease risk, but this would also reduce the availability of water for the banana plants themselves.The research was funded by the UK Global Food Security programme and the European Commission's Horizon 2020 programme.
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| 2,019 |
April 30, 2019
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https://www.sciencedaily.com/releases/2019/04/190430121744.htm
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Excessive rainfall as damaging to corn yield as extreme heat, drought
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Recent flooding in the Midwest has brought attention to the complex agricultural problems associated with too much rain. Data from the past three decades suggest that excessive rainfall can affect crop yield as much as excessive heat and drought. In a new study, an interdisciplinary team from the University of Illinois linked crop insurance, climate, soil and corn yield data from 1981 through 2016.
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The study found that during some years, excessive rainfall reduced U.S. corn yield by as much as 34% relative to the expected yield. Data suggest that drought and excessive heat caused a yield loss of up to 37% during some years. The findings are published in the journal "We linked county-level U.S. Department of Agriculture insurance data for corn loss with historical weather data, letting us quantify the impact of excessive rainfall on yield loss at a continental scale," said Kaiyu Guan, a natural resources and environmental sciences professor and the study's principal investigator. "This was done using crop insurance indemnity data paired with rigorous statistical analysis -- not modeled simulations -- which let the numbers speak for themselves."The study found that the impact of excessive rainfall varies regionally."Heavy rainfall can decrease corn yield more in cooler areas and the effect is exacerbated even further in areas that have poor drainage," said Yan Li, a former U. of I. postdoctoral researcher and lead author of the study.Excessive rainfall can affect crop productivity in various ways, including direct physical damage, delayed planting and harvesting, restricted root growth, oxygen deficiency and nutrient loss, the researchers said."It is challenging to simulate the effects of excessive rainfall because of the vast amount of seemingly minor details," Yan said. "It is difficult to create a model based on the processes that occur after heavy rainfall -- poor drainage due to small surface features, water table depth and various soil properties can lead to ponding of water in a crop field. Even though the ponding may take place over a small area, it could have a large effect on crop damage.""This study shows that we have a lot of work to do to improve our models," said Evan DeLucia, the director of the Institute for Sustainability, Energy and Environment, a professor of integrative biology and study co-author. "While drought and heat stress have been well dealt with in the existing models, excessive rainfall impacts on crop system are much less mature."Many climate change models predict that the U.S. Corn Belt region will continue to experience more intense rainfall events in the spring. Because of this, the researchers feel that it is urgent for the government and farmers to design better risk management plans to deal with the predicted climate scenarios."As rainfall becomes more extreme, crop insurance needs to evolve to better meet planting challenges faced by farmers," said Gary Schnitkey, a professor of agricultural and consumer economics and study co-author.
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Weather
| 2,019 |
April 29, 2019
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https://www.sciencedaily.com/releases/2019/04/190429134144.htm
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For low-income countries, climate action pays off by 2050
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Successful global efforts to substantially limit greenhouse gas emissions would likely boost GDP growth of poorer countries over the next 30 years, according to new research published in
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Researchers examined the impact global climate change mitigation would have on the economies of poorer countries -- specifically Malawi, Mozambique, and Zambia. Devastation in Mozambique and Malawi recently caused by Cyclones Idai and Kenneth vividly demonstrate the crippling impact that extreme weather events can have on these economies. Climate change is widely expected to increase the intensity and frequency of extreme weather events such as extreme heat, droughts, and floods as well as to magnify the destructive power of cyclones like Idai and Kenneth due to sea level rise.The study shows that beyond the benefits of reduced extreme weather in the long term, global mitigation efforts would also lower oil prices in coming decades, resulting in a significant economic boon for most poorer countries."It is abundantly clear that many low-income countries will bear the brunt of climate change impacts over the long term, and that successful efforts to rein in emissions will lessen this blow," said lead author Channing Arndt, director of the Environment and Production Technology Division at the International Food Policy Research Institute (IFPRI). "Our research now provides another rationale for robust climate action: the economic benefits of mitigation arrive much sooner than previously thought."Lowering greenhouse gas emissions creates two sources of economic gain for poorer countries. First, effective global mitigation policies would reduce changes in local weather patterns and lower the odds of damaging extreme events, allowing for more economic growth than if climate change is unimpeded and more extreme weather damages economic activity.Second, successful mitigation policies would cause oil prices to drop due to a reduction in oil demand. If richer nations take the lead in restraining their oil use, lower-income countries will be able to transition somewhat later while benefiting from much lower oil prices during the transition period. Since nearly all low-income countries are net oil importers, such price drops would represent a significant economic windfall.The research suggests that by 2050 these two sources of economic benefit together could increase the average GDP of Malawi, Mozambique, and Zambia by between 2 and 6 percentage points -- gains that cannot occur if greenhouse gas emissions continue unabated."Previous research into the economic impacts of global climate mitigation has tended to group oil exporters, such as Nigeria and Angola, and oil importers, such as Malawi and Zambia, together in a single aggregate region that both exports and imports oil," said Sergey Paltsev, deputy director of the MIT Joint Program on the Science and Policy of Global Change. "When you look at the impacts on a country level though, most low-income countries benefit not only from having a more stable climate but also from lower fuel prices, because they are net fuel importers and the import volumes are large relative to the size of their economies."How emissions policies should be structured globally remains an open question. The models producing these results assume that low-income countries are afforded space to transition more slowly because their contributions to global emissions are relatively low and such exemption allows low-income countries to proceed with the benefit of experience accumulated elsewhere. But the researchers caution that for climate mitigation to be effective, some developing countries cannot be exempted for long -- many middle-income countries will soon need to adhere to required emissions reductions."The impact of climate change is not likely to be distributed equally across the planet, and neither are any costs associated with reducing emissions," said Arndt. "We want to limit the deleterious effects of climate change on the environment and on people, particularly poor people, while avoiding harming development prospects in the process. The gains from effective mitigation shown by this research could help us achieve this goal."
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Weather
| 2,019 |
April 24, 2019
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https://www.sciencedaily.com/releases/2019/04/190424202543.htm
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'Catastrophic' breeding failure at one of world's largest emperor penguin colonies
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Emperor penguins at the Halley Bay colony in the Weddell Sea have failed to raise chicks for the last three years, scientists have discovered.
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Researchers from British Antarctic Survey (BAS) studied very high resolution satellite imagery to reveal the unusual findings, published today (25 April 2019) in the journal Until recently, the Halley Bay colony was the second largest in the world, with the number of breeding pairs varying each year between 14,000 -- 25,000; around 5-9% of the global emperor penguin population.The failure to raise chicks for three consecutive years is associated with changes in the local sea-ice conditions. Emperor penguins need stable sea-ice on which to breed, and this icy platform must last from April when the birds arrive, until December when their chicks fledge.For the last 60 years the sea-ice conditions in the Halley Bay site have been stable and reliable. But in 2016, after a period of abnormally stormy weather, the sea-ice broke up in October, well before any emperor chicks would have fledged.This pattern was repeated in 2017 and again in 2018 and led to the death of almost all the chicks at the site each season.The colony at Halley Bay colony has now all but disappeared, whilst the nearby Dawson Lambton colony has markedly increased in size, indicating that many of the adult emperors have moved there, seeking better breeding grounds as environmental conditions have changed.The re-location of many of the birds to a more stable breeding ground is encouraging, as until now it was not known whether the penguins would seek alternative sites in response to significant changes in their local environment.Lead author and BAS remote sensing specialist Dr Peter Fretwell said: "We have been tracking the population of this, and other colonies in the region, for the last decade using very high resolution satellite imagery."These images have clearly shown the catastrophic breeding failure at this site over the last three years. Our specialised satellite image analysis can detect individuals and penguin huddles, so we can estimate the population based on the known density of the groups to give reliable estimate of colony size."BAS penguin expert and co-author Dr Phil Trathan, said: "It is impossible to say whether the changes in sea-ice conditions at Halley Bay are specifically related to climate change, but such a complete failure to breed successfully is unprecedented at this site."Even taking into account levels of ecological uncertainty, published models suggest that emperor penguins numbers are set to fall dramatically, losing 50-70% of their numbers before the end of this century as sea-ice conditions change as a result of climate change."By using satellite imagery to study the behaviour of this colony and its response to catastrophic sea-ice loss scientists will gain vital information about how this iconic species might cope with future environmental change.
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Weather
| 2,019 |
April 24, 2019
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https://www.sciencedaily.com/releases/2019/04/190424125209.htm
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Geography study finds hot days lead to wildfires
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One of the best predictors of western wildfires could be how hot it's been, according to a new geography study by the University of Cincinnati.
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Geography professor Susanna Tong and her students studied a variety of weather, microclimate and ground conditions in historic fires around Phoenix, Arizona, and Las Vegas, Nevada, to determine which might be the most important in predicting the risk of wildfire.They found that temperature was a better predictor than humidity, rainfall, moisture content of the vegetation and soil and other factors. They presented their findings this month at the American Association of Geographers conference in Washington, D.C."We examined a long list of data. The results show that the maximum temperatures had the highest correlation with fires," UC student Diqi Zeng said. "That makes sense because if you have high temperatures, a fire is easier to ignite."California last year witnessed the deadliest wildfire of the past century in the United States -- a blaze that killed at least 88 people and caused an estimated $9 billion in damage, according to state insurers. Four of the state's five biggest wildfires on record have broken out since 2012.Identifying the risk factors is an important step in preventing future blazes, Tong said.UC student researcher Shitian Wan said she wanted to study wildfire after watching news coverage of the devastating 2018 Camp Fire in California, which her study referenced."The recent California wildfire, which is the deadliest and most destructive wildfire on record, showed clearly the devastating consequences. A better understanding of wildfire incidents is therefore crucial in fire prevention and future planning," their study said.Wan said she hopes research like hers will make a difference to people living in areas of high fire risk."What I'm trying to do is investigate the causal factors to create a risk map to examine where wildfires are most likely so people will be more informed," Wan said.UC students such as Yuhe Gao used geospatial and statistical tools to study the problem. The researchers found that the lack thereof even months prior to an event was a contributing factor."We found that precipitation even two months earlier can influence wildfires," UC student Wan said. "So if it rains a lot even two months ago, wildfires will be less likely."Likewise, the researchers found that wildfires were more likely to start in woodlands than pastures, possibly because more of those pastures are owned by ranchers who plan for fire by removing dead timber or brush and adding fire breaks.The researchers studied vegetation cover and type, moisture level, proximity to roads and population centers and historic weather data. Fires can be more harmful to vegetation in semiarid Arizona and Nevada than parts of California that get far more rainfall, Tong said."The plants around Phoenix and Las Vegas need a long regeneration time. Because of the rainfall in northern California the environment recovers from a fire relatively quickly," she said.Wildfires can be especially destructive in the Southwest because homes are sometimes built near or surrounded by natural areas. Surrounding trees and scrub can provide fuel for a devastating wildfire."They're infringing into the urban-wildland interface, so wildfire is of particular concern to them," Tong said. "That's where suburbia meets the woods. So property loss can be substantial if there is a wildfire."Finding long-term solutions to reduce fire risk will require a coordinated effort, Tong said.Planning boards can encourage smarter zoning practices in fire-prone areas. NASA can use remote sensing to keep track of ground or vegetation moisture content.Climatologists can build forecasts that help forestry officials plan for fire season and forestry officials can remove dead timber to minimize fires that do break out."It's a complex issue. Maybe better zoning regulations, better evacuation strategies, better forecasting and better monitoring," Tong said. "I think all of those are important."Students like Zeng said these geography studies are especially valuable now."Because of global warming, wildfires are only expected to get worse," Zeng said. "We need to better understand what causes these fires and how to control them."
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Weather
| 2,019 |
April 16, 2019
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https://www.sciencedaily.com/releases/2019/04/190416132155.htm
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What Earth's gravity reveals about climate change
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On March 17, 2002, the German-US satellite duo GRACE (Gravity Recovery and Climate Experiment) were launched to map the global gravitational field with unprecedented precision. After all, the mission lasted a good 15 years -- more than three times as long as expected. When the two satellites burnt up in the Earth's atmosphere at the end of 2017 and beginning of 2018, respectively, they had recorded the Earth's gravitational field and its changes over time in more than 160 months.
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This so-called time-resolved satellite gravimetry makes it possible, among other things, to monitor the terrestrial water cycle, the mass balance of ice sheets and glaciers or sea-level change, and thus to better understand the mechanisms of the global climate system, to assess important climatic trends more precisely and to predict possible consequences.A review in the journal GRACE produced the first direct measurement of ice-mass loss from ice sheets and glaciers ever. Previously, it had only been possible to estimate the masses and their changes using indirect methods. Within the first two years of the mission it was already possible to observe clear signals of ice-mass loss in Greenland and Antarctica. The measured data showed that that 60 percent of the total mass-loss is due to enhanced melt production in response to Arctic warming trends, while 40 percent is due to an increase of ice flow into the ocean. According to GRACE data, between April 2002 and June 2017 Greenland lost about 260 billion tons of ice per year, Antarctica about 140 billion tons. In addition to long-term trends, the gravity field data also provide evidence of the direct effects of global climate phenomena such as "El Niño" on ice sheets and glaciers worldwide.Among the most impactful contributions of the GRACE mission has been the unveiling of Earth's changing freshwater landscape, which has profound implications for water, food and human security. Global estimates of GRACE trends suggest increasing water storage in high and low latitudes, with decreased storage in mid-latitudes. Though the GRACE record is relatively short, this observation of large-scale changes in the global hydrological cycle has been an important early confirmation of the changes predicted by climate models through the twenty-first century.GRACE data also help to analyse and assess the sea level more accurately, as the storage of freshwater on land is linked to the sea level by various mechanisms. Analyses of GRACE data have enabled the first-ever estimates of groundwater storage changes from space. They confirm excessive rates of groundwater depletion from individual aquifers around the world. The data on terrestrial water storage have also contributed to the validation and calibration of various climate models.Within this century, sea-level rise could accelerate to 10 millimetres per year -- a rate unprecedented during the past 5000 years and a profound and direct consequence of a warming climate. High-precision sea-level measurements have been available since the early 1990s but they only show the absolute sea-level change. In the 25 years between 1993 and 2017, the sea-level rose by an average of 3.1 millimetres per year. To find out how thermal expansion, melting ice and the continental influx of water each affect sea-level, it is necessary to study the water's mass distribution. GRACE has shown that 2.5 millimetres of the average annual sea-level rise of 3.8 millimetres between 2005 and 2017 is caused by the inflow of water or other mass and 1.1 millimetres by the thermal expansion of water. Resolving this composition is important for sea-level projections. GRACE data provide a constraint on ocean mass change and thus indirectly on the Earth's energy imbalance, which is a fundamental global metric of climate change. GRACE has shown that most of the warming released by the rise in temperature occurs in the upper 2000 metres of the oceans, which are the most important energy sinks of climate change. GRACE also contributes to a better understanding of the dynamics and impact of ocean currents, in particular for the Arctic Ocean.The gravity field data of the GRACE satellites help to improve the United States Drought Monitor. This helps US authorities to react to droughts in a timely and sensible manner. With EGSIEM (European Gravity Service for Improved Emergency Management), the European Union has promoted a service designed to identify regional flood risks as early as possible. Between April and June 2017, test runs with historical flood data took place, showing that the wetness indicators for large river basins determined by GRACE can improve forecasts, for example for the Mississippi or the Danube. Current results also show that GRACE data can be used to more accurately predict the risk of seasonal wildfires.The GFZ operated the GRACE mission together with the German Aerospace Center (DLR) and on the US side with the NASA Jet Propulsion Laboratory (JPL). In May 2018, the follow-up mission GRACE Follow-on (GRACE-FO) was launched. The first monthly gravity field maps should be available to international users by the end of July this year. Unexpected difficulties delayed the submission of the products. "The reason was the failure of a control unit on the second GRACE-FO satellite," explains Frank Flechtner of GFZ. "This made it necessary to switch to the replacement unit installed for such scenarios. But now, with GRACE-FO, a more than two decades long recording of the mass changes in the system Earth is within reach." (ph)The greater the mass of an object, the greater its gravitational attraction. For example, the Alps exert a higher gravitational pull than the North German lowlands. When satellites orbit the Earth and fly over a massive region, they accelerate minimally when approaching it and slow down as they fly away.A tiny part of the gravitation emanating from the Earth is based on water on or near the surface in oceans, rivers, lakes, glaciers and underground. This water reacts to seasons, storms, droughts or other weather effects. GRACE took advantage of the mass displacement of water by recording its effect on the satellite duo that orbited our planet 220 kilometres in a row. Microwaves were used to measure their distance. This distance changed over time due to the mass shift on Earth. From the data, the researchers then calculated monthly maps of the regional changes in the Earth's gravitational pull and the causal changes in the masses on the surface.
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Weather
| 2,019 |
April 16, 2019
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https://www.sciencedaily.com/releases/2019/04/190416132110.htm
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Corals in the Red Sea offer long-term view of the south Asian summer monsoon
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When it comes to understanding future climate, the south Asian summer monsoon offers a paradox. Most climate models predict that as human-caused global warming increases, monsoon rain and wind will become more intense -- but weather data collected in the region shows that rainfall has actually declined over the past 50 years.
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A new study from Woods Hole Oceanographic Institution (WHOI) may help explain this discrepancy. Using chemical data from corals in the Red Sea, scientists reconstructed nearly three centuries of wind data that provided a definitive, natural record of the monsoon's intensity. The finding, published online March 28 in the journal "The south Asian monsoon is incredibly important," said Konrad Hughen, a paleoclimatologist at WHOI and co-author on the paper. "It's one of the biggest climate systems on the planet, and supplies water for almost a billion people -- yet we don't fully understand its long-term behavior. It's a very complicated system with lots of moving parts."The problem, he added, is that historic records of rainfall are based on limited points in space with high variability, and calculating averages across a broad region is difficult. Researchers have not yet had a way to verify those records, and have limited information about weather patterns before instrumental records began.Hughen and his colleagues were able to uncover that information thanks to the behavior of the monsoon winds themselves. One branch of the monsoon moves predominantly west to east, crossing the Sahara desert in northeast Africa, where it picks up fine dust and clay in the process. Its winds are then funneled through the Tokar Gap, a narrow mountain pass in eastern Sudan, where the dust they contain spills out into the Red Sea.The dust picked up in the Sahara contains a form of barium that dissolves easily in seawater. Each year, corals in the Red Sea incorporate part of that barium into their skeletons as they grow, trapping within them a record of how much wind and dust blew through the gap during summer monsoons for hundreds of years."The barium gives us a proxy for wind," said Hughen. "The more barium we found in a layer of coral, the more wind was coming though the Tokar Gap during the year it formed. Based on those winds, we can calculate the location of the low pressure systems that caused them, and we found they were primarily over the Indian subcontinent. That confirmed the winds' connection to the monsoon"The data in the corals seems to prove that historic records of rainfall may be missing a broader picture, Hughen said. Stronger winds would have increased moisture traveling over the Indian subcontinent, despite records showing rainfall dropping off."It could be that those records simply missed some of the rainfall, especially in the past when they were less reliable" he said. "Rain is highly variable from one place to another. Sometimes it's pouring just a few miles from an area that's not as wet. When you're recording rainfall at only a few fixed points, you might not be able to capture those sorts of spatial variations."The coral records show that the strength of the monsoon is in fact increasing with time -- a trend that's in keeping with existing climate models -- but its variability from decade to decade is diminishing. This suggests that as the climate has warmed, monsoon circulation has become more stable, so extra-heavy winds and rains could be the "new normal" for future years rather than just an anomaly.Also collaborating on the study were lead author Sean P. Bryan of Colorado State University and formerly a postdoctoral researcher at WHOI, J. Thomas Farrar of WHOI, and Kristopher B. Karnauskas of the University of Colorado, Boulder.
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Weather
| 2,019 |
April 15, 2019
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https://www.sciencedaily.com/releases/2019/04/190415154722.htm
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Predictability limit: Scientists find bounds of weather forecasting
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In the future, weather forecasts that provide storm warnings and help us plan our daily lives could come up to five days sooner before reaching the limits of numerical weather prediction, scientists said.
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"The obvious question that has been raised from the very beginning of our whole field is, what's the ultimate limit at which we can predict day-to-day weather in the future," said Fuqing Zhang, distinguished professor of meteorology and atmospheric science and director of the Center for Advanced Data Assimilation and Predictability Techniques at Penn State. "We believe we have found that limit and on average, that it's about two weeks."Reliable forecasts are now possible nine to 10 days out for daily weather in the mid-latitudes, where most of Earth's population lives. New technology could add another four to five days over the coming decades, according to research published online in the The research confirms a long-hypothesized predictability limit for weather prediction, first proposed in the 1960s by Edward Lorenz, a Massachusetts Institute of Technology mathematician, meteorologist and pioneer of the chaos theory, scientists said."Edward Lorenz proved that one cannot predict the weather beyond some time horizon, even in principle," said Kerry Emanuel, professor of atmospheric science at MIT and coauthor of the study. "Our research shows that this weather predictability horizon is around two weeks, remarkable close to Lorenz's estimate."Unpredictability in how weather develops means that even with perfect models and understanding of initial conditions, there is a limit to how far in advance accurate forecasts are possible, scientists said."We used state-of-the-art models to answer this most fundamental question," said Zhang, lead author on the study. "I think in the future we'll refine this answer, but our study demonstrates conclusively there is a limit, though we still have considerable room to improve forecast before reaching the limit."To test the limit, Zhang and his team used the world's two most advanced numerical weather prediction modeling systems -- The European Center for Medium Range Weather Forecasting and the U.S. next generation global prediction system.They provided a near-perfect picture of initial conditions and tested how the models could recreate two real-world weather events, a cold surge in northern Europe and flood-inducing rains in China. The simulations were able to predict the weather patterns with reasonable accuracy up to about two weeks, the scientists said.Improvements in day-to-day weather forecasting have implications for things like storm evacuations, energy supply, agriculture and wild fires."We have made significant advances in weather forecasting for the past few decades, and we're able to predict weather five days in advance with high confidence now," Zhang said. "If in the future we can predict additional days with high confidence, that would have a huge economic and social benefit."Researchers said better data collection, algorithms to integrate data into models and improved computing power to run experiments are all needed to further improve our understanding of initial conditions."Achieving this additional predictability limit will require coordinated efforts by the entire community to design better numerical weather models, to improve observations, and to make better use of observations with advanced data assimilation and computing techniques," Zhang said.
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Weather
| 2,019 |
April 15, 2019
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https://www.sciencedaily.com/releases/2019/04/190415154656.htm
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Climate change could undermine children's education and development in the tropics
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Education of children is one of the ambitious goals for sustainable development as a way to alleviate poverty and reduce vulnerability to climate change and natural disasters. Yet, a new study by a University of Maryland researcher published in the April 15, 2019, issue of the journal
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University of Maryland researcher Heather Randell, lead author who conducted the synthesis study as a postdoctoral fellow at the National Socio-Environmental Synthesis Center, and co-author Clark Gray, of the University of North Carolina at Chapel Hill, found that climatic conditions affect education attainment adversely in multiple ways. In Southeast Asia, which historically has high heat and humidity, exposure to higher-than-average temperatures during prenatal and early childhood has a harmful effect on schooling and is associated with fewer years of attending school. In West and Central Africa, and Southeast Asia, greater rainfall in early life is associated with higher levels of education. In Central America and the Caribbean, children who experienced more than typical rainfall had the lowest predicted education.Surprisingly, children from the most educated households were not cushioned from the climate effects, and they experienced the greatest penalties when they felt hotter and drier conditions in early life.In the study, Randell and Gray investigated the links between extreme temperature and precipitation in early life and educational attainment in 29 countries in the global tropics. The research has implications for determining vulnerability to climate change and development trajectories."If climate change undermines educational attainment, this may have a compounding effect on underdevelopment that over time magnifies the direct impacts of climate change," the authors write. "As the effects of climate change intensify, children in the tropics will face additional barriers to education." The authors expected that children from better educated households would fare better, but found instead that climate change could erode the development and education gains in the tropics, even for better-off households, who have the most to lose as their advantages wear away.Randell explained that as children in the tropics feel the intensifying effects of climate change, they will face additional barriers to education and this is more evidence of the varied social impacts of climate change. Policies to safeguard children in these exposed populations, for example making sure pregnant women and young children can get relief from high heat and humidity, or providing heat or drought tolerant crop varieties, could limit long term impacts of climate change, Randell explained."While these results may not be directly related to schools, they are important factors in early life that affect a kid's school trajectory," said Randell. "People rarely think about how kids' education is directly linked to climate. But this is really important given the extent that climate change is impacting extreme weather events. We need to better understand what gains in education are possible, and how climate change can act as a barrier to achieving the Sustainable Development Goals. We have to take climate into account, plan for it, and design policies to create more resilient populations given that we know climate impacts are going to be worse in the next decade."Randell and Gray's
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April 15, 2019
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https://www.sciencedaily.com/releases/2019/04/190415143955.htm
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North Atlantic warming hole impacts jet stream
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The North Atlantic warming hole (NAWH), a region of reduced warming located in the North Atlantic Ocean, significantly affects the North Atlantic jet stream in climate simulations of the future, according to a team of researchers.
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Sea surface temperatures (SST) are projected to increase in most of the world's oceans as the result of global climate change. However, within an area of rotating ocean currents just south of Greenland an anomaly exists where colder sea-surface temperatures were documented in both global climate-model projections and in observations."It's called a hole because there is a lack of warming," said Melissa Gervais, assistant professor of meteorology and atmospheric science, Penn State, who used the Community Earth System model (CESM) to investigate the impact of the NAWH on atmospheric circulation and midlatitude jets. "We found that this region of the ocean is a really important place for forcing the jet stream that goes across the North Atlantic Ocean."The researchers published their findings in the Development of the NAWH is linked to a slowdown of the Atlantic Meridional Overturning Circulation, a large system of ocean currents that carry warm water from the tropics northwards into the North Atlantic, and is thought to be caused by an influx of fresh water coming from melting Arctic sea ice.Previous research by Gervais and her team demonstrated that this increase in fresh water to the ocean changes circulation patterns and leads to surface cooling."With more Arctic sea ice melting, more fresh water flows into the Labrador Sea, which leads to a reduction in deep convection," said Gervais who also is an Institute for CyberScience co-hire. "That changes the ocean circulation, allowing it to cool in that region south of Greenland."This cooling pattern, relative to global average SST increase, is predicted to become greater and more apparent relative to the internal ocean variability as the 21st century progresses."These changes in SST patterns occur as the result of changes in ocean circulation and could have a significant impact on atmospheric circulation and the North Atlantic storm track in the future," said Gervais.Jet streams, high altitude currents of wind flowing above the Earth, transport air masses and drive weather patterns. The relationship between climate change and jet streams is complex and understanding the potential impact of climate change on jet streams is crucial for understanding changes in weather patterns and storm tracks."With climate change we have some ideas about how the jets are going to change. In general, we expect to see a poleward shift and eastward elongation of the jet," said Gervais. "Right now, it's sort of a tug of war between impacts of the tropics and impacts of the arctic. So those two things are competing to shift where the jet is located."Most climate models seem to agree that the Pacific jet stream is going to shift poleward but there is a lot of variability in predictions for the Atlantic, said Gervais.To investigate how the development of the NAWH impacts the jet stream, the team conducted a series of large-ensemble, atmospheric model experiments in the CESM with prescribed SST and sea ice levels over three different time periods."We ran three simulations," said Gervais. "One with current warming-hole conditions; one where the ocean temperature was increased to fill in the warming hole; and one where its size was twice as deep, to simulate more freshwater from melting ice sheets."Their results indicate that the NAWH plays an important role in midlatitude atmospheric circulation changes in the model's future climate simulations."We found that it's really quite important for that region," said Gervais. "The NAWH seems to be elongating the jet even further and shifting it a little bit north. Instead of just thinking about how the tropics and arctic amplification are influencing the jet, we now also need to think about how this warming hole is going to influence the jet. These local changes in the North Atlantic jet are of a similar magnitude to the full climate-change response in the region, indicating that the North Atlantic warming hole could be an important additional factor in the tug of war on midlatitude circulation, that has received little attention."
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April 12, 2019
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https://www.sciencedaily.com/releases/2019/04/190412085236.htm
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Predicting heat waves? Look half a world away
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When heavy rain falls over the Indian Ocean and Southeast Asia and the eastern Pacific Ocean, it is a good indicator that temperatures in central California will reach 100°F in four to 16 days, according to a collaborative research team from the University of California, Davis, and the Asia-Pacific Economic Cooperation (APEC) Climate Center in Busan, South Korea.
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The results were published in Heat waves are common in the Central California Valley, a 50-mile-wide oval of land that runs 450 miles from just north of Los Angeles up to Redding. The valley is home to half of the nation's tree fruit and nut crops, as well as extensive dairy production, and heat waves can wreak havoc on agricultural production. The dairy industry had a heat wave-induced economic loss of about $1 billion in 2006, for instance. The ability to predict heat waves and understand what causes them could inform protective measures against damage."We want to know more about how extreme events are created," said Richard Grotjahn, corresponding author on the paper and professor in the UC Davis Department of Land, Air and Water Resources. "We know that such patterns in winter are sometimes linked with areas of the tropics where thunderstorms are enhanced. We wondered if there might be similar links during summer for those heat waves."The scientists analyzed the heat wave data from June through September from 1979 to 2010. The data were collected by 15 National Climatic Data Centers stations located throughout the Valley. From these data, the researchers identified 24 heat waves. They compared these instances to the phases of a large, traveling atmospheric circulation pattern called the Madden-Julian Oscillation, or MJO.The MJO manifests as heavy rain that migrates across the tropical Indian and then Pacific Oceans, and researchers have shown that it influences winter weather patterns."It's well known that tropical rainfall, such as the MJO, has effects beyond the tropics," said Yun-Young Lee of the APEC Climate Center in Busan, South Korea, the paper's first author. "So a question comes to mind: Is hot weather in the Central California Valley partly attributable to tropical rainfall?"Lee and Grotjahn found that, yes, enhanced rainfall in the tropics preceded each heat wave in specific and relatively predictable patterns. They also found that hot weather in the valley is most common after more intense MJO activity in the eastern Pacific Ocean, and next most common after strong MJO activity in the Indian Ocean."The more we know about such associations to large-scale weather patterns and remote links, the better we can assess climate model simulations and therefore better assess simulations of future climate scenarios," Grotjahn said.
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April 11, 2019
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https://www.sciencedaily.com/releases/2019/04/190411101810.htm
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Warm winds in autumn could strain Antarctica's Larsen C ice shelf
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The Antarctic Peninsula is the northernmost part of Earth's coldest continent, making it particularly vulnerable to a changing global climate. Surface melting of snow and ice initiated the breakup of the peninsula's northernmost Larsen A ice shelf in 1995, followed in 2002 by the Larsen B ice shelf to the south, which lost a section roughly the size of Rhode Island.
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New University of Maryland-led research shows that the Larsen C ice shelf -- the fourth largest ice shelf in Antarctica, located just south of the former Larsen B shelf -- experienced an unusual spike in late summer and early autumn surface melting in the years 2015 to 2017. The study, spanning 35 years from 1982 to 2017, quantifies how much of this additional melting can be ascribed to warm, dry air currents called foehn winds that originate high in the peninsula's central mountain range.The study further shows that the three-year spike in foehn-induced melting late in the melt season has begun to restructure the snowpack on the Larsen C ice shelf. If this pattern continues, it could significantly alter the density and stability of the Larsen C ice shelf, potentially putting it at further risk to suffer the same fate as the Larsen A and B shelves.The researchers used two different methods to quantify patterns of foehn-induced melt from climate model outputs that correspond to real-world satellite observations and weather station data. They published their findings on April 11, 2019 in the journal "Three years doesn't make a trend. But it's definitely unusual that we are seeing enhanced foehn winds and associated melting in late summer and early autumn," said Rajashree Tri Datta, a faculty assistant at UMD's Earth System Science Interdisciplinary Center and the lead author of the research paper. "It's unusual that we're seeing increased foehn-induced melt in consecutive years -- especially so late in the melt season, when the winds are stronger but the temperatures are usually cooling down. This is when we expect melting to end and the surface to be replenished with snow."Enhanced surface melting causes water to trickle into the underlying layers of firn -- or uncompacted, porous snow -- in the upper layers of the ice sheet. This water then refreezes, causing the normally porous, dry firn layers to become denser. Eventually, the firn layers can become too dense for water to enter, leading to a buildup of liquid water atop the ice shelf."With enhanced densification, the ice enters the next warm season with a very different structure. Our modeling results show that, with less open space for the surface water to filter into, runoff increases year after year," said Datta, who also has an appointment at NASA's Goddard Space Flight Center. "The dominant theory suggests that enhanced densification led to the fracture of the Larsen A and B shelves. Despite an overall decrease in peak summer melt over the last few years, episodic melting late in the melt season could have an outsized impact on the density of the Larsen C ice shelf."As foehn winds race down the colder eastern slopes of the Antarctic Peninsula's central mountain range, they can raise air temperatures by as much as 30 degrees Fahrenheit, producing localized bursts of snowmelt. According to Datta, these winds exert their greatest effects at the bases of glacial valleys. Here, where the feet of the glaciers adjoin the Larsen C ice shelf, foehn winds stand to destabilize some of the most fragile and critical structures in the system."The Larsen C ice shelf is of particular interest because it's among the most vulnerable in Antarctica," Datta explained. "Because it's a floating ice shelf, a breakup of Larsen C wouldn't directly lead to a rise in global mean sea level. However, the ice shelf does brace against the flow of the glaciers that feed it. So if Larsen C goes, some of these glaciers will be free to accelerate their rate of flow and melt, which will result in a rise in global sea level."
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Weather
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April 9, 2019
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https://www.sciencedaily.com/releases/2019/04/190409162809.htm
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New model accurately predicts harmful space weather
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A new, first-of-its-kind space weather model reliably predicts space storms of high-energy particles that are harmful to many satellites and spacecraft orbiting in the Earth's outer radiation belt. A paper recently published in the journal
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"Society's growing reliance on modern-technology infrastructures makes us especially vulnerable to space weather threats," said Yue Chen, a space scientist at Los Alamos National Laboratory and lead author of the study. "If our GPS or communications satellites fail, it could have wide-reaching, negative impacts on everything from air travel to bank transactions. So being able to accurately predict space weather has been a goal for a long time. This model is a firm step towards being able to do that."At the Earth's equator, the outer radiation belt -- also called the outer Van Allen belt -- begins approximately 8,000 miles above the Earth and ends beyond 30,000 miles. High-speed high-energy electrons inside this belt are known for their high variability, especially during solar storms, when new particles from the sun enter the Earth's space environment -- making them extremely difficult to predict.This model takes the unique approach of connecting the dots between the killer electron population and the measurements made by a Los Alamos National Laboratory geosynchronous equatorial orbiting satellite, as well as a National Oceanic and Atmospheric Administration satellite in low-Earth orbit within a 3.5-year period. By establishing a correlation between the electrons and satellite measurements in low-Earth orbit, Chen and his colleagues were able to identify the informational triggers needed for predictions and develop a reliable model to forecast changes of high-energy electrons within the outer belt."We're very excited about the potential for future enhancements to this model," said Chen. "The more research and refinements we do, the increased potential for us to have more reliable forecasts with longer warning time before the arrival of new killer electrons."
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Weather
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March 27, 2019
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https://www.sciencedaily.com/releases/2019/03/190327203440.htm
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Cities under pressure in changing climate
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Cities to swelter as planners face unenviable trade-off between tackling climate change and quality of life, new research has shown.
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The study, led by experts at Newcastle University, UK, has shown the challenge we face to reduce greenhouse gas emissions, increase cities' resilience to extreme weather and also give people quality space to live in.Publishing the research in the journal Focussing on London -- an example of a large rapidly growing city that is also at the forefront of tackling climate change -- the team show the 'best case' scenario would be to increase development in a small number of central locations, such as East Barnet, Wood Green and Ealing.Avoiding development along the Thames, this optimum plan would reduce flood risk, minimise transport emissions and reduce urban sprawl.But, says author Dr Dan Caparros-Midwood, the trade-off will be more people exposed to extreme temperatures."Many of the lowest heat hazard areas coincide with the flood zone on the banks of the River Thames due to the cooling effect of blue infrastructure," explains Dr Caparros-Midwood, who carried out the work as part of his PhD at Newcastle University and is now a Senior GIS Specialist at Wood."But moving development away from the river while also protecting our green spaces and reducing sprawl really only leaves two options; either shrinking our homes or developing in higher heat risk areas."And while our study looked at London, this could apply to most cities in the world."By 2050 it is estimated that two-thirds of the world's population will live in cities, highlighting the urgent need for urban development to be sustainable."Urban areas must radically transform if they are to reduce their greenhouse gas emissions and consumption of resources whilst also increasing their resilience to climate change and extreme weather," explains Professor Stuart Barr, co-author and part of the Geospatial Engineering group at Newcastle University.Project lead Professor Richard Dawson, of the School of Engineering at Newcastle University, said the findings reinforced the scale of the challenge."We are already starting to see the impact of hotter summers and flooding on our cities," he says."Balancing trade-offs between these objectives is complex as it spans sectors such as energy, buildings, transport, and water."What our study shows in stark detail is this cannot be done using our current approach to planning and engineering our cities -- difficult choices will have to be made."Even in Europe, says Professor Dawson, only a quarter of cities have a comprehensive climate strategy. And yet, with the right impetus, we have the potential to accelerate and upscale action in our cities to tackle climate change."We have to be more creative about how we design and build our buildings and infrastructure," he says."This will include weaving green infrastructure into urban spaces; facilitating lifestyle choices such as walking and cycling that reduce energy demand, pollution and greenhouse gas emissions; and integrating new technologies that can shift carbon-intensive energy patterns by optimizing transport efficiency, vehicle sharing and reducing congestion."For the moment though, there are difficult, and often irreconcilable, trade-offs to be made in urban areas and we need to be making them now."
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Weather
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March 27, 2019
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https://www.sciencedaily.com/releases/2019/03/190327161247.htm
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Arctic warming contributes to drought
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When the Arctic warmed after the ice age 10,000 years ago, it created perfect conditions for drought.
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According to new research led by a University of Wyoming scientist, similar changes could be in store today because a warming Arctic weakens the temperature difference between the tropics and the poles. This, in turn, results in less precipitation, weaker cyclones and weaker mid-latitude westerly wind flow -- a recipe for prolonged drought.The temperature difference between the tropics and the poles drives a lot of weather. When those opposite temperatures are wider, the result is more precipitation, stronger cyclones and more robust wind flow. However, due to the Arctic ice melting and warming up the poles, those disparate temperatures are becoming closer."Our analysis shows that, when the Arctic is warmer, the jet stream and other wind patterns tend to be weaker," says Bryan Shuman, a UW professor in the Department of Geology and Geophysics. "The temperature difference in the Arctic and the tropics is less steep. The change brings less precipitation to the mid-latitudes."Shuman is a co-author of a new study that is highlighted in a paper, titled "Mid-Latitude Net Precipitation Decreased With Arctic Warming During the Holocene," published today (March 27) online in Researchers from Northern Arizona University; Universite Catholique de Louvain in Louvain-In-Neuve, Belgium; the Florence Bascom Geoscience Center in Reston, Va.; and Cornell University also contributed to the paper."The Currently, the northern high latitudes are warming at rates that are double the global average. This will decrease the equator-to-pole temperature gradient to values comparable with the early to middle Holocene Period, according to the paper.Shuman says his research contribution, using geological evidence, was helping to estimate how dry conditions have been in the past 10,000 years. His research included three water bodies in Wyoming: Lake of the Woods, located above Dubois; Little Windy Hill Pond in the Snowy Range; and Rainbow Lake in the Beartooth Mountains."Lakes are these natural recorders of wet and dry conditions," Shuman says. "When lakes rise or lower, it leaves geological evidence behind."The researchers' Holocene temperature analysis included 236 records from 219 sites. During the past 10,000 years, many of the lakes studied were lower earlier in history than today, Shuman says."Wyoming had several thousand years where a number of lakes dried up, and sand dunes were active where they now have vegetation," Shuman says. "Expanding to the East Coast, it is a wet landscape today. But 10,000 years ago, the East Coast was nearly as dry as the Great Plains."The research group looked at the evolution of the tropic-to-pole temperature difference from three time periods: 100 years ago, 2,000 years ago and 10,000 years ago. For the last 100 years, many atmospheric records facilitated the analysis but, for the past 2,000 years or 10,000 years, there were fewer records available. Tree rings can help to expand studies to measure temperatures over the past 2,000 years, but lake deposits, cave deposits and glacier ice were studied to record prior temperatures and precipitation."This information creates a test for climate models," Shuman says. "If you want to use a computer to make a forecast of the future, then it's useful to test that computer's ability to make a forecast for some other time period. The geological evidence provides an excellent test."The research was funded by the Science Foundation Arizona Bisgrove Scholar Award, the National Science Foundation and the state of Arizona's Technology and Research Initiative Fund administered by the Arizona Board of Regents.
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March 26, 2019
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https://www.sciencedaily.com/releases/2019/03/190326113534.htm
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Cold water currently slowing fastest Greenland glacier
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NASA research shows that Jakobshavn Glacier, which has been Greenland's fastest-flowing and fastest-thinning glacier for the last 20 years, has made an unexpected about-face. Jakobshavn is now flowing more slowly, thickening, and advancing toward the ocean instead of retreating farther inland. The glacier is still adding to global sea level rise -- it continues to lose more ice to the ocean than it gains from snow accumulation -- but at a slower rate.
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The researchers conclude that the slowdown of this glacier, known in the Greenlandic language as Sermeq Kujalleq, occurred because an ocean current that brings water to the glacier's ocean face grew much cooler in 2016. Water temperatures in the vicinity of the glacier are now colder than they have been since the mid-1980s.In a study published in The scientists were so shocked to find the change, Khazendar said: "At first we didn't believe it. We had pretty much assumed that Jakobshavn would just keep going on as it had over the last 20 years." However, the OMG mission has recorded cold water near Jakobshavn for three years in a row.The researchers suspect the cold water was set in motion by a climate pattern called the North Atlantic Oscillation (NAO), which causes the northern Atlantic Ocean to switch slowly between warm and cold every five to 20 years. The climate pattern settled into a new phase recently, cooling the Atlantic in general. This change was accompanied by some extra cooling in 2016 of the waters along Greenland's southwest coast, which flowed up the west coast, eventually reaching Jakobshavn.When the climate pattern flips again, Jakobshavn will most likely start accelerating and thinning again.Josh Willis of JPL, the principal investigator of OMG, explained, "Jakobshavn is getting a temporary break from this climate pattern. But in the long run, the oceans are warming. And seeing the oceans have such a huge impact on the glaciers is bad news for Greenland's ice sheet."Jakobshavn, located on Greenland's west coast, drains about 7 percent of the island's ice sheet. Because of its size and importance to sea level rise, scientists from NASA and other institutions have been observing it for many years.Researchers hypothesized that the rapid retreat of the glacier began with the early 2000s loss of the glacier's ice shelf -- a floating extension of the glacier that slows its flow. When ice shelves disintegrate, glaciers often speed up in response. Jakobshavn has been accelerating each year since losing its ice shelf, and its front (where the ice reaches the ocean) has been retreating. It lost so much ice between 2003 and 2016 that its thickness, top to bottom, shrank by 500 feet (152 meters).The research team combined earlier data on ocean temperature with data from the OMG mission, which has measured ocean temperature and salinity around the entire island for the last three summers. They found that in 2016, water in Jakobshavn's fjord cooled to temperatures not seen since the 1980s."Tracing the origin of the cold waters in front of Jakobshavn was a challenge," explained Ian Fenty of JPL, a co-author of the study. "There are enough observations to see the cooling but not really enough to figure out where it came from." Using an ocean model called Estimating the Circulation and Climate of the Ocean (ECCO) to help fill in the gaps, the team traced the cool water upstream (toward the south) to a current that carries water around the southern tip of Greenland and northward along its west coast. In 2016, the water in this current cooled by more than 2.7 degrees Fahrenheit (1.5 degrees Celsius).Although the last few winters were relatively mild in Greenland itself, they were much colder and windier than usual over the North Atlantic Ocean. The cold weather coincided with the switch in the NAO climate pattern. Under the influence of this change, the Atlantic Ocean near Greenland cooled by about 0.5 degrees Fahrenheit (1 degree Celsius) between 2013 and 2016. These generally cooler conditions set the stage for the rapid cooling of the ocean current in southwest Greenland in early 2016. The cooler waters arrived near Jakobshavn that summer, at the same time that Jakobshavn slowed dramatically.The team suspects that both the widespread Atlantic cooling and the dramatic cooling of the waters that reached the glacier were driven by the shift in the NAO. If so, the cooling is temporary and warm waters will return when the NAO shifts to a warm phase once again.The warming climate has increased the risk of melting for all land ice worldwide, but many factors can speed or slow the rate of ice loss. "For example," Khazendar said, "the shape of the bed under a glacier is very important, but it is not destiny. We've shown that ocean temperatures can be just as important."Tom Wagner, NASA Headquarters program scientist for the cryosphere, who was not involved in the study, said, "The OMG mission deployed new technologies that allowed us to observe a natural experiment, much as we would do in a laboratory, where variations in ocean temperatures were used to control the flow of a glacier. Their findings -- especially about how quickly the ice responds -- will be important to projecting sea level rise in both the near and distant future."The paper on the new research in
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Weather
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March 25, 2019
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https://www.sciencedaily.com/releases/2019/03/190325122022.htm
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Antarctic snowfall dominated by a few extreme snowstorms
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A new study reveals the importance of a small number of intense storms around Antarctica in controlling the amount of snow falling across the continent.
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Published in the journal In one particular case, 44% of annual snowfall occurred in a single day. Understanding the significance of these events is critical for scientists interpreting Antarctica's past, as well as predicting how our climate may behave in future.The Antarctic ice sheet is extremely important because of its potential contribution to global sea level rise. The mass of the ice sheet is constantly changing because of the ice gained by snowfall compared with the loss of ice at the margins via iceberg calving and melting.Lead author, Prof. John Turner, from British Antarctic Survey, says: "Antarctica is already the most extreme continent on earth -- the windiest, the coldest, the driest. But even by Antarctic standards, we were surprised to see the extent to which a small number of extreme snowfall events are responsible for the marked differences in snowfall from year to year."They are often short-lived events, which arrive suddenly and deposit a large fraction of the year's snowfall. If you are an ice core scientist trying to decipher messages from our past climate, and predict the future, knowing about these extreme weather events can be the missing part of the jigsaw."The international team, comprising scientists from India, France, China, Netherlands and the UK, were able to investigate snowfall across the Antarctic from 1979 to 2016 using the output of an atmospheric model called RACMO2. This was developed by Dutch researchers, and revealed the impact of the most extreme snow storms.BAS Ice Core scientist, and co-author on the paper, Dr Liz Thomas says: "Ice cores are invaluable in reconstructing past climate. However, an ice core site that is dominated by snowfall from occasional extreme storms might not be representative of climate conditions through the year."This new study will help ensure that future ice cores are not drilled in regions dominated by precipitation extremes."
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Weather
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March 22, 2019
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https://www.sciencedaily.com/releases/2019/03/190322105718.htm
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Climate changes make some aspects of weather forecasting increasingly difficult
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The ongoing climate changes make it increasingly difficult to predict certain aspects of weather, according to a new study from Stockholm University. The study, focusing on weather forecasts in the northern hemisphere spanning 3- 10 days ahead, concludes that the greatest uncertainty increase will be regarding summer downfalls, of critical importance when it comes to our ability to predict and prepare for flooding.
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The study How Global Warming Changes the Difficulty of Synoptic Weather Forecasting by Sebastian Scher and Gabriele Messori at the Department of Meteorology, published in In the studied span of medium-range weather forecasting (3-10 days) the most prominent uncertainty seems to befall the ability to predict the volume of summer rain. Certain other parameters, such as temperature and air pressure, are on the other hand likely to become more accurate."Reliable weather forecasts are tremendously important for almost all of society, and summer flooding in the northern hemisphere especially is one of the great challenges as the climate is getting warmer" says Sebastian Scher, main author. "It is very important that meteorological institutes around the world are given the opportunity to develop their tools and methods as conditions change."The research project at Stockholm University will continue, during the next step specifically focusing on the ability to predict heavy summer downpours in 24-48 hours.
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Weather
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March 20, 2019
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https://www.sciencedaily.com/releases/2019/03/190320141105.htm
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Arctic sea ice 2019 wintertime extent is seventh lowest
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Sea ice in the Arctic appears to have hit its annual maximum extent after growing through the fall and winter. The 2019 wintertime extent reached on March 13 ties with 2007's as the 7th smallest extent of winter sea ice in the satellite record, according to scientists at the NASA-supported National Snow and Ice Data Center and NASA.
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This year's maximum extent peaked at 5.71 million square miles (14.78 million square kilometers) and is 332,000 square miles (860,000 square kilometers) below the 1981 to 2010 average maximum -- equivalent to missing an area of ice larger than the state of Texas.The Arctic sea ice cover, an expanse of frozen seawater floating on top of the Arctic Ocean and surrounding seas, thickens and expands during the fall and winter months. The sea ice hits its maximum yearly extent sometime between late February and early April. It thins and shrinks during the spring and summer until it reaches its annual minimum extent in September.Beyond its seasonal wax and wane cycles, Arctic sea ice extent has been plummeting during both the growing and melting seasons over the last 40 years. The 2019 maximum extent breaks a string of record or near-record lows that started in 2015 -- but that does not necessarily mean that Arctic sea ice is recovering."While this year wasn't a record low, the maximum extent still points to there being a sustained decline in winter sea ice," said Melinda Webster, a sea ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The temperatures in the Arctic were a bit higher than average and we saw a lot of ice loss in the Bering Sea, but nothing this winter was as extreme or dramatic compared to recent years and the record lows."Rising temperatures in the Arctic over the past decades have also thinned the sea ice pack. Multiyear ice, the older and thicker ice that acted like a bastion against melting for the rest of the sea ice cover, has mostly disappeared. A 2018 study led by Ron Kwok, a sea ice researcher with NASA's Jet Propulsion Laboratory in Pasadena, California, found that 70 percent of the ice pack now consists of seasonal ice -- sea ice that grows rapidly in the winter only to melt during the next summer."The large changes in ice coverage associated with the loss of the multiyear ice pack have already occurred," Kwok said. "The seasonal ice now represents a larger fraction of the Arctic sea ice cover. Because this young ice is thinner and grows faster in the winter, it is more responsive to weather and makes the sea ice cover respond differently than before. It's not that we won't see new wintertime or summertime record lows in the next years -- it's just that the variability is going to be higher."
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Weather
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March 20, 2019
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https://www.sciencedaily.com/releases/2019/03/190320141042.htm
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Tropical storms likely to become more deadly as climate changes
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Tropical storms are likely to become more deadly under climate change, leaving people in developing countries, where there may be a lack of resources or poor infrastructure, at increased risk, new research from Oregon State University shows.
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Under most climate models, tropical storm-related deaths would increase up to 52 percent as the climate changes, said Todd Pugatch, an associate professor of economics in the College of Liberal Arts at OSU and the study's author."Tropical storms can strike quickly, leaving little opportunity to escape their path, and the impact on developing countries is significant," Pugatch said. "Understanding the effects of these storms, and how those effects may change as the climate changes, can help governments and people better prepare in the future, and hopefully save lives."The findings were published recently in the journal Pugatch's research focuses on international economic development. Climate change will likely have the greatest impact on vulnerable populations in the developing world. Mortality risk is the most basic form of vulnerability to natural disasters, so Pugatch wanted to better understand how mortality and climate change might be linked.His first step was to attempt to quantify the effects of tropical storms on mortality in Mexico from 1990 to 2011. He used meteorological data to measure storm strength and death records to estimate storm-related mortality.If deaths in a Mexican state exceeded historical norms for a particular month, the model attributed those deaths to the storm. This methodology has the ability to avert the subjectivity of official death counts and get to a more authentic number, Pugatch said.He found that tropical storms killed approximately 1,600 people during the study period."Whether a particular death is caused by a storm isn't always obvious," he said. "There may also be political motivations to alter counts. Officials might overstate counts to draw more aid money or understate the number of deaths to make the government appear more competent."The next step for his research was to simulate how the number of storm-related deaths would be impacted by climate change. He used climate modeling scenarios to see how increased weather volatility due to climate change might have impacted deaths during the study period of 1990 to 2011.In five of six scenarios modeling climate change impacts on storm frequency and windspeed, a measure of storm intensity, deaths would have increased, with the highest projection showing a 52 percent increase.However, one simulation showed a decrease of up to 10 percent, because in that scenario, the frequency of tropical storms decreases enough to reduce deaths. The other models fell within the two extremes, but death rates rose in all but one."If the decrease in storm frequency outweighs the increase in severity, storm-related deaths could fall," Pugatch said. "Most indications are that storms are more likely to become more deadly as the climate changes."The findings look specifically at Mexico, but similar results are likely to be seen in other developing countries, where natural disasters can be particularly devastating because communities lack essential resources, Pugatch said."I wouldn't expect these results to apply to the same extent in developed countries like the U.S.," he said. "But there is some relevance to the U.S. Hurricanes Katrina and Harvey showed that strong storms can lead to tremendous loss of life and physical damage even in the U.S."More research is needed to understand how climate change may alter storm frequency and severity in the future, Pugatch said. Public policy may also play a role in mitigating or exacerbating the effects of tropical storms, he said."The more we understand the mortality effects of storms, the more we can use that information to develop strategies to prepare," Pugatch said. "Investing in strengthened response systems now could avert future deaths."
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Weather
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March 20, 2019
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https://www.sciencedaily.com/releases/2019/03/190320110627.htm
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Supercomputer simulations shed light on how liquid drops combine
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Scientists have revealed the precise molecular mechanisms that cause drops of liquid to combine, in a discovery that could have a range of applications.
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Insights into how droplets merge could help make 3D printing technologies more accurate and may help improve the forecasting of thunderstorms and other weather events, the study suggests.A team of researchers from the Universities of Edinburgh and Warwick ran molecular simulations on a supercomputer to analyse interactions between tiny ripples that form on the surface of droplets.These ripples -- known as thermal-capillary waves -- are too small to be detected by the naked eye or by using the most advanced experimental techniques.Researchers found that these tiny waves cross the gap between nearby droplets and make the first contact between them.Once the droplets have touched, liquid molecules draw the two surfaces together like the zip on a jacket, the team says. This leads to the complete merger of the droplets.Studying the dynamics of merging droplets could help to improve understanding of the conditions that cause raindrops to form in developing storm clouds, the team says.The team used the ARCHER UK National Supercomputing Service -- operated by EPCC, the University's high-performance computing facility -- to run their simulations. These used thousands of processors to model interactions between nearly five million atoms.The research, published in the journal Lead researcher Sreehari Perumanath, of the University of Edinburgh's School of Engineering, said: "We now have a good understanding of how droplets combine at a molecular level. These insights, combined with existing knowledge, may enable us to better understand rain drop growth and development in thunderstorms, or improve the quality of printing technologies. The research could also aid in the design of next-generation liquid-cooling systems for new high-powered electronics."Dr James Sprittles, from the Mathematics Institute at the University of Warwick, said: "The theoretical framework developed for the waves on nanoscale droplets enabled us to understand Edinburgh's remarkable molecular simulation data. Critically, the new theory allows us to predict the behaviour of larger engineering-scale droplets, which are too big for even ARCHER to capture, and enable new experimental discoveries."
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Weather
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March 12, 2019
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https://www.sciencedaily.com/releases/2019/03/190312123645.htm
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Climate Change: Heat-induced heart attack risk on the rise
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The environment can have a major effect on the human cardiovascular system. It has long been assumed that severe spikes in temperature increase the risk of heart attack. "In the case of very high and very low temperatures in particular, this has been clearly demonstrated. In this latest study, we wanted to see to what extent the heat and cold-related heart attack risk has changed over the years," explains Dr. Kai Chen, researcher at the Institute of Epidemiology at Helmholtz Zentrum München.
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Together with colleagues from Ludwig Maximilian University in Munich, Augsburg University Hospital and Nördlingen Hospital, he examined data from the Myocardial Infarction Register Augsburg. The study looked at more than 27,000 heart attack patients between 1987 and 2014. The average age of the patients studied was around 63, 73% were men and about 13,000 ended in the death of the patient. The individual heart attacks were compared against meteorological data on the day of the attack and adjusted for a range of additional factors, such as the day of the week and socioeconomic status. The key finding from the study, explains Chen was that, "Over a period of 28 years, we found that there has been an increase in heat-induced heart attack risk in recent years."In order to demonstrate this, the researchers compared data from 1987 to 2000 with data from 2001 to 2014. "Our analysis showed that, over the last few years, the risk of heat-induced heart attack with increasing average daily temperature has risen compared to the previous investigation period," explains Chen. Individuals with diabetes or hyperlipidaemia were particularly at risk over the latter period. The researchers suspect that this is partly a result of global warming, but that it is also a consequence of an increase in risk factors such as diabetes and hyperlipidaemia, which have made the population more susceptible to heat.Is climate change a heart attack risk?"Our study suggests that greater consideration should be given to high temperatures as a potential trigger for heart attacks -- especially in view of climate change," explains lead researcher Dr. Alexandra Schneider. "Extreme weather events, like the 2018 heat waves in Europe, could in future result in an increase in cardiovascular disease. At the same time, there is likely to be a decrease in cold-related heart attacks here in Germany. Our analysis suggests a lower risk in the future, but this lower risk was not significant and very cold days will continue to represent a potential trigger for heart attacks." To what extent increases in heat-related heart attacks will be counterbalanced by a decrease in cold-related heart attacks is not yet clear, explains the epidemiologist. Her group is currently performing extrapolations aimed at modelling this change in risk both in scenarios where the world meets the Paris Agreement's 1.5 °C and 2 °C targets and in scenarios where these targets are missed.In addition, the researchers are also planning to corroborate their findings by carrying out additional, multicenter studies.
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Weather
| 2,019 |
March 12, 2019
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https://www.sciencedaily.com/releases/2019/03/190312075916.htm
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Coal power stations disrupt rainfall: Global study
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Modern coal-fired power stations produce more ultrafine dust particles than road traffic and can even modify and redistribute rainfall patterns, a new 15-year international study shows.
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The study indicates filtration systems on modern coal-fired power stations are the biggest source of ultrafine particles and can have considerable impacts on climate in several ways.In urban areas, road traffic has long been considered the main source of small particle emissions which have the potential to adversely affect health and the environment.However, long-term measurements carried out by two scientists, Professor Wolfgang Junkermann from the Karlsruhe Institute of Technology (KIT) in Germany and Professor Jorg Hacker from Airborne Research Australia -- who are affiliated with Flinders University -- have revealed a source that particularly affects regional climate: modern coal-fired power stations.In the The research also found UFP concentrations have increased continuously since modern coal-fired power stations were commissioned in many locations around the world.For the measurement flights in Europe, Australia and even Mexico and Inner Mongolia, the research team used two rather unusual small research aircraft, the world's most comprehensively instrumented motorglider in Australia and a 'trike' developed in Germany -- believed to be the smallest manned research aircraft worldwide.The flying laboratories are equipped with highly sensitive instruments and sensors measuring dust particles, trace gases, temperature, humidity, wind and energy balances."Our two research aircraft are particularly suitable to follow the plumes from the smoke stacks downwind for hundreds of kilometres and study their behaviour in great detail," says Professor Hacker, who is based at Airborne Research Australia (ARA) in South Australia.The scientists then linked these data with meteorological observations and used dispersion and transport models to trace back their origin."In this way, we found that fossil power stations have for many years become the strongest individual sources of ultrafine particles worldwide. They massively influence meteorological processes and may cause extreme weather events, including intensive rain events."By redistributing rainfall events, this can lead to drier than usual conditions in some places and to unusually heavy and persistent strong rainfall elsewhere," Professor Hacker says.With a diameter of less than 100 nm, UFP have an enormous impact on environmental processes, capable of influencing the properties of clouds and precipitation, the paper says."The UFP offer surfaces for chemical reactions in the atmosphere or may influence the properties of clouds and precipitation," says Professor Junkermann.In open nature, forest fires, dust storms or volcanic eruptions produce fine particles, but mostly not in the nanometer range.To study the existence and distribution and transport processes of UFP, the researchers not only flew their instruments near to or downwind of coal-fired power stations but also over remote regions where very low UFP concentrations have been measured in the past at ground level.Specifically, in regions with conspicuous precipitation trends such as inland Western Australia and Queensland, the researchers found that UFP concentrations have increased constantly and could be linked to emissions made by coal-fired power stations and refineries."Exhaust gas cleaning takes place under conditions that are optimal for the new formation of particles. Ammonia is added to the exhaust gases in order to convert nitrogen oxides into harmless water and nitrogen," Professor Junkermann says.At the same time ammonia is available at the right mixing ratio for particle formation, resulting in concentrations in the exhaust gas becoming high. After emission at 200-300 m height from smoke stacks, the very small particles typically spread over several hundreds of kilometres depending on weather and climate conditions in the atmosphere, the researchers found.
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Weather
| 2,019 |
March 7, 2019
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https://www.sciencedaily.com/releases/2019/03/190307091457.htm
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It's raining on the Greenland ice -- in the winter
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Rainy weather is becoming increasingly common over parts of the Greenland ice sheet, triggering sudden melting events that are eating at the ice and priming the surface for more widespread future melting, says a new study. Some parts of the ice sheet are even receiving rain in winter -- a phenomenon that will spread as climate continues to warm, say the researchers. The study appears this week in the European scientific journal
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Greenland has been losing ice in recent decades due to progressive warming. Since about 1990, average temperatures over the ice sheet have increased by as much as 1.8 degrees C (3.2F) in summer, and up to 3 degrees C (5.4F) in winter. The 660,000-square-mile sheet is now believed to be losing about 270 billion tons of ice each year. For much of this time, most of this was thought to come from icebergs calving into the ocean, but recently direct meltwater runoff has come to dominate, accounting for about 70 percent of the loss. Rainy weather, say the study authors, is increasingly becoming the trigger for that runoff.The researchers combined satellite imagery with on-the-ground weather observations from 1979 to 2012 in order to pinpoint what was triggering melting in specific places. Satellites are used to map melting in real time because their imagery can distinguish snow from liquid water. About 20 automated weather stations spread across the ice offer concurrent data on temperature, wind and precipitation. Combining the two sets of data, the researchers zeroed in on more than 300 events in which they found the initial trigger for melting was weather that brought rain. "That was a surprise to see," said the study's lead author, Marilena Oltmanns of Germany's GEOMAR Centre for Ocean Research. She said that over the study period, melting associated with rain and its subsequent effects doubled during summer, and tripled in winter. Total precipitation over the ice sheet did not change; what did change was the form of precipitation. All told, the researchers estimate that nearly a third of total runoff they observed was initiated by rainfall.Melting can be driven by a complex of factors, but the introduction of liquid water is one of the most powerful, said Marco Tedesco, a glaciologist at Columbia University's Lamont-Doherty Earth Observatory and coauthor of the study. Warm air, of course, can melt ice directly, but is not very efficient by itself, he said. However, warmer temperatures can produce cascading effects. One is that they make it more likely that atmospheric conditions will pass the threshold where precipitation comes down as rain, not snow. Liquid water carries a great deal of heat, and when it soaks into a snowy surface, it melts the snow around it, releasing more energy. Meanwhile, the warm air that brought the rain often forms clouds, which hem in the heat.This combination of factors produces a pulse of melting that feeds on itself, and well outlasts the rain itself, often by several days. Furthermore, the scientists found that the length of these pulses increased over the decades they analyzed, in cold weather from two days to three, and in the brief summer, from two days to five.There are longer-term effects, say the study authors. They believe that part of the meltwater runs off, but the rest refreezes in place, morphing normally fluffy, reflective snow on or near the surface into darker, denser masses of ice. This ice absorbs solar radiation more easily than snow, so when the sun comes out, it melts more easily, producing more liquid water, which feeds more melting, in a vicious feedback loop. This, said Tedesco, has led to more and earlier melting in the summer. And because the surface has been hardened into ice, much of that meltwater can more easily flow off the ice sheet toward the sea."If it rains in the winter, that preconditions the ice to be more vulnerable in the summer," said Tedesco. "We are starting to realize, you have to look at all the seasons."While rain is hitting increasingly far-flung parts of the ice in summer, winter rainfall so far appears mostly confined to lower elevations in south and southwest Greenland. It is brought in by moist, relatively warm ocean winds from the south, which some communities in other areas call neqqajaaq. These winds may be getting more common due to climate-induced shifts in the jet stream. The elevation of the ice sheet increases further inland and it is thus colder and snowier there; but if average temperatures continue to increase as expected, the line where the moisture comes down as rain instead of snow will rapidly move inward, upward and northward. "The ice should be gaining mass in winter when it snows, but an increasing part of the mass gain from precipitation is lost by melt," said Oltmanns.Greenland is not the only place in the far north affected by increasing rain. In recent years, anomalous winter rains have hit the northern Canadian tundra, then refrozen over the surface, sealing in plants that caribou and musk oxen normally forage through the loose snow; in some years, this has decimated herds. And a just-published study from near Fairbanks, Alaska, shows that increasing spring rains are percolating down through the permafrost, thawing it and releasing large amounts of methane, a highly efficient greenhouse gas.Between 1993 and 2014, global sea-level rise accelerated from about 2.2 millimeters a year to 3.3 millimeters, and much of that acceleration is thought to be due to melting in Greenland. Projections of sea-level rise for the end of this century generally range from two to four feet, but most projections do not yet account for what may happen to the ice in Greenland, nor with the much larger mass in Antarctica, because understanding of the physics is still not advanced enough.Richard Alley, a prominent glaciologist at Pennsylvania State University, said that the new paper adds to the understanding. "The big picture is clear and unchanged," he said. "Warming melts ice," But, he added, the specific processes that will carry this "need to be quantified, understood and incorporated into models. This new paper does important work understanding and quantifying."The study was coauthored by Fiammetta Straneo of Scripps Institution of Oceanography.
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Weather
| 2,019 |
March 6, 2019
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https://www.sciencedaily.com/releases/2019/03/190306110708.htm
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Good news! Europe's electric grid will still work even as the world crumbles
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Scientists at Aarhus University in Denmark studying the effects of climate change on weather-dependent electricity systems have found a silver lining in Earth's otherwise fraught future outlook. Temperatures may climb and seas may rise, but the lights (and, undoubtedly, the air conditioning) will still be on in nations with high capacities for wind and solar energy. The research, published March 6 in the journal
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Using data from weather models and climate time series, the team developed models that predict wind turbine and solar panel output for all European countries under the most common global warming scenarios through the year 2100. In order to compare how a European weather-dependent electrical grid functions in these projections with how it functioned historically, the scientists selected five key metrics: need and capacity for dispatchable electricity (which can be stored and used on demand by power grid operators), benefit of electrical transmission, benefit of electrical storage, and variability of electricity production and consumption. These metrics measure the most important aspects of a large-scale renewable-heavy electricity system and are abstract enough that the team could use them to draw general conclusions without focusing on a specific technology mix."Most other energy system studies assume a number of technologies and seek to combine them in a cost-optimal way to cover the demand," says Smail Kozarcanin, a PhD fellow in the Department of Engineering and the first author of the study. "In this study, we seek to understand, for example, how climate change affects the system independent of which technologies are used to cover the demand that remains unmet by wind and solar. To the best of our knowledge, this technology-independent focus in combination with high-resolution data on climate change projections is unique to our study."Despite the new weather extremes predicted by future climate scenarios, the study didn't find a large difference in the key metrics for renewable electrical systems, suggesting that system designs based on historical weather should perform similarly in future climates. Kozarcanin and his colleagues believe this is because current systems are designed to withstand extreme weather events -- they simply don't have to withstand them now as often as they will in the future. The team also notes that European demand for electrified heating and cooling will actually dip slightly as the climate warms, since the demand for air conditioning is much less than that for heating at European latitudes. This relaxed demand will counterbalance the slight decrease in wind and solar energy output their models predict."Extreme weather might require changes to the renewable generators and other parts of the system," says Kozarcanin. "For example, future wind turbines may require new types of storm protection and solar panels could need protection against super hailstorms. But our study shows that large-scale infrastructure choices, such as back-up power plant capacity, are relatively unaffected by the level of climate change."However, the team does believe that the European electrical grid will still require some tweaking to operate efficiently in the future. Transmission capacities are well developed within most nations, but the massive interconnected electrical system spanning 24 countries across Central Europe will need a boost to effectively transmit renewable energy between nations."The main challenge for future grids will most likely be political and societal will to make the investments and proper planning for a grid topology that provides most of the potential benefit from smoothing renewable energy production between countries," says Kozarcanin.If humans fail to mitigate the apocalyptic heatwaves and superstorms to come, at least it seems probable that we can hole up in our climate-controlled living rooms and watch HBO Nordic. Indefinitely.
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Weather
| 2,019 |
March 5, 2019
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https://www.sciencedaily.com/releases/2019/03/190305092832.htm
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Weather-responsive intersections could ease traffic congestion
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Cities could ease congestion and improve safety during snowstorms by tweaking the timing of traffic lights to take road conditions into account.
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Researchers at the University of Waterloo collected data and ran computer simulations to determine that adjusting the signals at intersections in bad weather could reduce delays by up to 20 per cent."We need to have weather-responsive signal plans," said Liping Fu, a civil and environmental engineering professor at Waterloo. "Their timing should recognize weather conditions and change accordingly."Signals in modern cities are timed using optimization models that analyze factors including traffic volume and speed to safely get as many vehicles as possible through intersections."The problem is that those parameters all assume normal weather conditions," said Fu, director of the Innovative Transportation System Solutions (iTSS) Lab. "In the winter, if the road surface is covered with snow and ice and visibility is poor, the numbers are not the same."Researchers analyzed hours of video taken at a busy intersection near campus to measure how motorists alter their driving during snowstorms in terms of speed, stopping distance and other variables.That data was then used in computer simulations to optimize the timing of signals -- the green, yellow and red intervals, for instance -- at a single intersection and on a stretch of road with four co-ordinated intersections.Changes were also made to improve safety, such as increasing the yellow interval to account for vehicles travelling slower and requiring more time to stop.At the single intersection, changes to increase safety and reduce delays almost cancelled each other out.But even with adjustments to help avoid crashes, intersection delays in the co-ordinated corridor, especially in moderate traffic, decreased by up to 20 per cent.Fu said cities with computerized signal systems are already equipped to remotely and inexpensively adjust the timing of traffic lights to reap those benefits when snowstorms hit.Next steps include the development of technology using video cameras and artificial intelligence (AI) software to automatically tweak the timing of lights in response to traffic changes caused by weather, accidents or construction."Ultimately we want signal controls so smart that they actually change themselves in real time based on what is happening in the road network for any reason," Fu said.
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Weather
| 2,019 |
February 28, 2019
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https://www.sciencedaily.com/releases/2019/02/190228141259.htm
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2015-2016 El Niño triggered disease outbreaks across globe
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The 2015-2016 El Niño event brought weather conditions that triggered regional disease outbreaks throughout the world, according to a new NASA study that is the first to comprehensively assess the public health impacts of the major climate event on a global scale.
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El Niño is an irregularly recurring climate pattern characterized by warmer than usual ocean temperatures in the equatorial Pacific, which creates a ripple effect of anticipated weather changes in far-spread regions of Earth. During the 2015-2016 event, changes in precipitation, land surface temperatures and vegetation created and facilitated conditions for transmission of diseases, resulting in an uptick in reported cases for plague and hantavirus in Colorado and New Mexico, cholera in Tanzania, and dengue fever in Brazil and Southeast Asia, among others."The strength of this El Niño was among the top three of the last 50 years, and so the impact on weather and therefore diseases in these regions was especially pronounced," said lead author Assaf Anyamba, a research scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "By analyzing satellite data and modeling to track those climate anomalies, along with public health records, we were able to quantify that relationship."The study utilized a number of climate datasets, among them land surface temperature and vegetation data from the Moderate Resolution Imaging Spectroradiometer aboard NASA's Terra satellite, and NASA and National Oceanic and Atmospheric Administration precipitation datasets. The study was published Feb. 13 in the journal Nature Based on monthly outbreak data from 2002 to 2016 in Colorado and New Mexico, reported cases of plague were at their highest in 2015, while the number of hantavirus cases reached their peak in 2016. The cause of the uptick in both potentially fatal diseases was an El Niño-driven increase in rainfall and milder temperatures over the American Southwest, which spurred vegetative growth, providing more food for rodents that carry hantavirus. A resulting rodent population explosion put them in more frequent contact with humans, who contract the potentially fatal disease mostly through fecal or urine contamination. As their rodent hosts proliferated, so did plague-carrying fleas.A continent away, in East Africa's Tanzania, the number of reported cases for cholera in 2015 and 2016 were the second and third highest, respectively, over an 18-year period from 2000 to 2017. Cholera is a potentially deadly bacterial infection of the small intestine that spreads through fecal contamination of food and water. Increased rainfall in East Africa during the El Niño allowed for sewage to contaminate local water sources, such as untreated drinking water. "Cholera doesn't flush out of the system quickly," Anyamba said, "so even though it was amplified in 2015-2016, it actually continued into 2017 and 2018. We're talking about a long-tailed, lasting peak."In Brazil and Southeast Asia, during the El Niño dengue fever proliferated. In Brazil the number of reported cases for the potentially deadly mosquito-borne disease in 2015 was the highest from 2000 to 2017. In Southeast Asia, namely Indonesia and Thailand, the number of reported cases, while relatively low for an El Niño year, was still higher than in neutral years. In both regions, the El Niño produced higher than normal land surface temperatures and therefore drier habitats, which drew mosquitoes into populated, urban areas containing the open water needed for laying eggs. As the air warmed, mosquitoes also grew hungrier and reached sexual maturity more quickly, resulting in an increase in mosquito bites.The strong relationship between El Niño events and disease outbreaks underscores the importance of existing seasonal forecasts, said Anyamba, who has been involved with such work for the past 20 years through funding from the U.S. Department of Defense. Countries where these outbreaks occur, along with the United Nations' World Health Organization and Food and Agriculture Organization, can utilize these early warning forecasts to take preventive measures to minimize the spread of disease. Based on the forecast, the U.S. Department of Defense does pre-deployment planning, and the U.S. Department of Agriculture (USDA) takes measures to ensure the safety of imported goods."Knowledge of the linkages between El Niño events and these important human and animal diseases generated by this study is critical to disease control and prevention, which will also mitigate globalization," said co-author Kenneth Linthicum, USDA center director at an entomology laboratory in Gainesville, Florida. He noted these data were used in 2016 to avert a Rift Valley fever outbreak in East Africa. "By vaccinating livestock, they likely prevented thousands of human cases and animal deaths.""This is a remarkable tool to help people prepare for impending disease events and take steps to prevent them," said co-author William Karesh, executive vice president for New York City-based public health and environmental nonprofit EcoHealth Alliance. "Vaccinations for humans and livestock, pest control programs, removing excess stagnant water -- those are some actions that countries can take to minimize the impacts. But for many countries, in particular the agriculture sectors in Africa and Asia, these climate-weather forecasts are a new tool for them, so it may take time and dedicated resources for these kinds of practices to become more utilized."According to Anyamba, the major benefit of these seasonal forecasts is time. "A lot of diseases, particularly mosquito-borne epidemics, have a lag time of two to three months following these weather changes," he said. "So seasonal forecasting is actually very good, and the fact that they are updated every month means we can track conditions in different locations and prepare accordingly. It has the power to save lives."
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Weather
| 2,019 |
February 25, 2019
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https://www.sciencedaily.com/releases/2019/02/190225170252.htm
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Tweets tell scientists how quickly we normalize unusual weather
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What kinds of weather do people find remarkable, when does that change, and what does that say about the public's perception of climate change? A study led by the University of California, Davis, examined those questions through the lens of more than 2 billion U.S. Twitter posts.
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The study, published Feb. 25 in the journal "There's a risk that we'll quickly normalize conditions we don't want to normalize," said lead author Frances C. Moore, an assistant professor in the UC Davis Department of Environmental Science and Policy. "We are experiencing conditions that are historically extreme, but they might not feel particularly unusual if we tend to forget what happened more than about five years ago."To reach their conclusions, the researchers quantified a timeless and universal pastime -- talking about the weather -- by analyzing posts on Twitter.They sampled 2.18 billion geolocated tweets created between March 2014 and November 2016 to determine what kind of temperatures generated the most posts about weather. They found that people often tweet when temperatures are unusual for a particular place and time of year -- a particularly warm March or unexpectedly freezing winter, for example.However, if the same weather persisted year after year, it generated less comment on Twitter, indicating that people began to view it as normal in a relatively short amount of time.This phenomenon, note the authors, is a classic case of the boiling-frog metaphor: A frog jumps into a pot of boiling hot water and immediately hops out. If, instead, the frog in the pot is slowly warmed to a boiling temperature, it doesn't hop out and is eventually cooked. While scientifically inaccurate, this metaphor has long been used as a cautionary tale warning against normalizing the steadily changing conditions caused by climate change.Sentiment analysis tools, which measure the positive or negative association of words, provided evidence for this "boiling-frog effect." After repeat exposures to historically-extreme temperatures, people tweeted less about the weather specifically, but they still expressed negative sentiments overall. Particularly cold or hot conditions still seemed to make people unhappy and grumpy."We saw that extreme temperatures still make people miserable, but they stop talking about it," Moore said. "This is a true boiling-frog effect. People seem to be getting used to changes they'd prefer to avoid. But just because they're not talking about it doesn't mean it's not making them worse off."The study's co-authors are Nick Obradovich of Massachusetts Institute of Technology, Flavio Lehner from National Center for Atmospheric Research and Patrick Baylis from University of British Columbia.
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Weather
| 2,019 |
February 22, 2019
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https://www.sciencedaily.com/releases/2019/02/190222143342.htm
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Predicting the monsoon a year ahead
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With average precipitation of 35 inches per four-month season over an area encompassing most of the Indian subcontinent, the South Asia summer monsoon is intense, only partly understood, and notoriously difficult to predict. Until now, according to findings by Nir Y. Krakauer, a City College of New York civil engineer.
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Because of the monsoon's enormous impact on these sectors, his research is of importance to a range of activities, including agriculture, industry, fishing and hydropower.A frequent visitor to the region, stretching from Nepal to Sri Lanka, Krakauer has devised a methodology that allows forecasts potentially up to a year in advance. Currently, most predictions are made about two months in advance of the South Asia monsoon season that runs from June to September, but it is not known how far ahead skillful forecasts might be possible."People usually use one or two predictors for forecasts," said the Grove School of Engineering associate professor who is also affiliated with the CCNY-based NOAA-CREST. "Many of these predictors are one or another pattern of sea surface temperatures. My question was how do you find which patterns are important for forecasting the monsoon -- the amount of rain and where it will be?"Unlike other forecasters who use only the sea surface temperature readings from neighboring waters, Krakauer looked at the predictive potential of all the common patterns in the sea surface temperature map. He developed prediction methods using global sea surface temperature and monsoon precipitation data from between 1901 to 1996, and tested the performance of his prediction methods on data from 1997-2017."What I found is that two methods seem to do a good job of forecasting the monsoon. I looked at the sea surface temperatures at the beginning of the monsoon, and going back as far as four years before."His finding was that, generally, the closer to the beginning of the monsoon season, the more accurate forecasts that are based on sea surface temperature can be. But predictions with some accuracy can be made as far as a year in advance.Getting a better sense of how much water will be available is particularly important given that the rainfall is getting more intense in South Asia while the total amount remains constant, meaning that more rain is falling in a shorter period. This could be problematic for farmers in the region.His work in South Asia has been partly supported by USAID, most recently as part of the US-Pakistan Center for Advanced Studies on Water program.
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Weather
| 2,019 |
February 15, 2019
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https://www.sciencedaily.com/releases/2019/02/190215082343.htm
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Surprise findings turn up the temperature on the study of vernalization
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Researchers have uncovered new evidence about the agriculturally important process of vernalization in a development that could help farmers deal with financially damaging weather fluctuations.
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Vernalization is the process by which plants require prolonged exposure to cold temperature before they transition from the vegetative state to flower. For decades it's been a key focus of research into plant development and crop productivity.But how vernalization might work under variable temperatures in the field has been unclear, as have some of the underlying molecular controls of the process.The research carried out by John Innes Centre scientists in collaboration with colleagues in Hungary and France shows that vernalization is influenced by warm conditions as well as cold, and a much wider temperature range than previously thought.Led by Dr Laura Dixon, the study began as an exploration into how variance in ambient temperatures might influence flowering regulation in winter wheat. But it unexpectedly uncovered an "extreme vernalization response.""We have shown that vernalization responds to warmer conditions than those classically associated with vernalizing. Before this study we thought vernalization only happened up to a maximum of about 12°C, but the true temperature is much higher. This information is immediately useful to breeders," says Dr Dixon.The researchers used a panel of 98 wheat cultivars and landraces and exposed them to temperatures ranging from 13 to 25 °C in controlled environments.Normally, once the vernalization process completes, plant growth is accelerated under warm temperatures. But the team identified one cultivar, named Charger, which did not follow this standard response.Gene expression analysis revealed that the wheat floral activator gene (VRN-A1) was responsible for this trait. Further experiments showed that expression of genes that delay flowering is reactivated in response to high temperatures (of up to 24 °C), demonstrating that vernalization is not only a consequence of how long the plant experiences continuous cold.This study published in the journal The team is now looking to provide diagnostic genetic markers which will allow breeders to track the distinct allele responsible for this warm-temperature vernalization trait. They also hope to use their new knowledge of warm weather interruption to reduce the length of vernalization in the breeding cycle, so that new wheat lines can be generated more quickly.Dr Dixon explains: "This study highlights that to understand the vernalization response in agriculture we must dissect the process in the field and under variable conditions. The knowledge can be used to develop new wheat cultivars that are more robust to changing temperatures."
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February 14, 2019
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https://www.sciencedaily.com/releases/2019/02/190214115551.htm
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Artificial intelligence to boost Earth system science
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A study by German scientists from Jena and Hamburg, published today in the journal
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In the past decades mainly static attributes have been investigated using machine learning approaches, such as the distribution of soil properties from the local to the global scale. For some time now, it has been possible to tackle more dynamic processes by using more sophisticated deep learning techniques. This allows for example to quantify the global photosynthesis on land with simultaneous consideration of seasonal and short term variations."From a plethora of sensors, a deluge of Earth system data has become available, but so far we've been lagging behind in analysis and interpretation," explains Markus Reichstein, managing director of the Max Planck Institute for Biogeochemistry in Jena, directory board member of the Michael-Stifel-Center Jena (MSCJ) and first author of the publication. "This is where deep learning techniques become a promising tool, beyond the classical machine learning applications such as image recognition, natural language processing or AlphaGo," adds co-author Joachim Denzler from the Computer Vision Group of the Friedrich Schiller University Jena (FSU) and member of MSCJ. Examples for application are extreme events such as fire spreads or hurricanes, which are very complex processes influenced by local conditions but also by their temporal and spatial context. This also applies to atmospheric and ocean transport, soil movement, and vegetation dynamics, some of the classic topics of Earth system science.However, deep learning approaches are difficult. All data-driven and statistical approaches do not guarantee physical consistency per se, are highly dependent on data quality, and may experience difficulties with extrapolations. Besides, the requirement for data processing and storage capacity is very high. The publication discusses all these requirements and obstacles and develops a strategy to efficiently combine machine learning with physical modeling. If both techniques are brought together, so-called hybrid models are created. They can for example be used for modeling the motion of ocean water to predict sea surface temperature. While the temperatures are modelled physically, the ocean water movement is represented by a machine learning approach. "The idea is to combine the best of two worlds, the consistency of physical models with the versatility of machine learning, to obtain greatly improved models," Markus Reichstein further explains.The scientists contend that detection and early warning of extreme events as well as seasonal and long-term prediction and projection of weather and climate will strongly benefit from the discussed deep-learning and hybrid modelling approaches.
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February 13, 2019
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https://www.sciencedaily.com/releases/2019/02/190213090822.htm
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New clue in curious case of cassowary casque
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A team of Australian scientists has completed research that could help solve a 200-year-old mystery surrounding an iconic Australian bird.
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The La Trobe University researchers have published new evidence in Danielle Eastick, from La Trobe's Department of Ecology, Environment and Evolution and her team have shown the cranial structure acts like a radiator or "thermal window" to help the large, flightless birds keep cool in hot weather."Our results are quite compelling and it's highly probable this is what the casque is actually used for," Ms Eastick said."It's really exciting to think we may have solved a mystery that has baffled scientists for so long."Using a handheld thermal imaging device, Ms Eastick obtained readings from 20 captive cassowaries, from Victoria through to northern Queensland and in different weather conditions.The images showed that the birds released minimal heat from their casque when the weather was just five degrees and the greatest levels when the mercury reached 36 degrees.Ms Eastick explained that as a large bodied, dark feathered creature, which is native to northern Queensland and Papua New Guinea, cassowaries face a thermal challenge in high temperatures."Just as humans sweat and dogs pant in hot weather or following exercise, cassowaries offload heat from their casque in order to survive. The hotter the ambient temperature, the more heat they release.""The casque has caused considerable curiosity and speculation for nearly two centuries and animal experts have proposed various theories, including that it's a protective weapon used for fighting other animals or a means of attracting the opposite sex, but all are inconclusive."The "thermal window" explanation may provide a rare glimpse into the physiology of dinosaurs."Many dinosaurs also had casques, so it's possible they too helped keep cool this way."
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Weather
| 2,019 |
February 12, 2019
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https://www.sciencedaily.com/releases/2019/02/190212081540.htm
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Earth's magnetic shield booms like a drum when hit by impulses
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The Earth's magnetic shield booms like a drum when it is hit by strong impulses, according to new research from Queen Mary University of London.
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As an impulse strikes the outer boundary of the shield, known as the magnetopause, ripples travel along its surface which then get reflected back when they approach the magnetic poles.The interference of the original and reflected waves leads to a standing wave pattern, in which specific points appear to be standing still while others vibrate back and forth. A drum resonates like this when struck in exactly the same way.This study, published in Movements of the magnetopause are important in controlling the flow of energy within our space environment with wide-ranging effects on space weather, which is how phenomena from space can potentially damage technology like power grids, GPS and even passenger airlines.The discovery that the boundary moves in this way sheds light on potential global consequences that previously had not been considered.Dr Martin Archer, space physicist at Queen Mary University of London, and lead author of the paper, said: "There had been speculation that these drum-like vibrations might not occur at all, given the lack of evidence over the 45 years since they were proposed. Another possibility was that they are just very hard to definitively detect."Earth's magnetic shield is continuously buffeted with turbulence so we thought that clear evidence for the proposed booming vibrations might require a single sharp hit from an impulse. You would also need lots of satellites in just the right places during this event so that other known sounds or resonances could be ruled out. The event in the paper ticked all those quite strict boxes and at last we've shown the boundary's natural response."The researchers used observations from five NASA THEMIS satellites when they were ideally located as a strong isolated plasma jet slammed into the magnetopause. The probes were able to detect the boundary's oscillations and the resulting sounds within the Earth's magnetic shield, which agreed with the theory and gave the researchers the ability to rule out all other possible explanations.Many impulses which can impact our magnetic shield originate from the solar wind, charged particles in the form of plasma that continually blow off the Sun, or are a result of the complicated interaction of the solar wind with Earth's magnetic field, as was technically the case for this event.The interplay of Earth's magnetic field with the solar wind forms a magnetic shield around the planet, bounded by the magnetopause, which protects us from much of the radiation present in space.Other planets like Mercury, Jupiter and Saturn also have similar magnetic shields and so the same drum-like vibrations may be possible elsewhere.Further research is needed to understand how often the vibrations occur at Earth and whether they exist at other planets as well. Their consequences also need further study using satellite and ground-based observations.
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Weather
| 2,019 |
February 11, 2019
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https://www.sciencedaily.com/releases/2019/02/190211105400.htm
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Climate change may destroy tiger's home
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A James Cook University scientist says the last coastal stronghold of an iconic predator, the endangered Bengal tiger, could be destroyed by climate change and rising sea levels over the next 50 years.
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"Fewer than 4,000 Bengal tigers are alive today," said JCU's Professor Bill Laurance, a co-author of the study."That's a really low number for the world's biggest cat, which used to be far more abundant but today is mainly confined to small areas of India and Bangladesh," he said."Spanning more than 10,000 square kilometres, the Sundarbans region of Bangladesh and India is the biggest mangrove forest on Earth, and also the most critical area for Bengal tiger survival," said lead-author Dr Sharif Mukul, an assistant professor at Independent University Bangladesh."What is most terrifying is that our analyses suggest tiger habitats in the Sundarbans will vanish entirely by 2070," said Dr Mukul.The researchers used computer simulations to assess the future suitability of the low-lying Sundarban region for tigers and their prey species, using mainstream estimates of climatic trends from the Intergovernmental Panel on Climate Change. Their analyses included factors such as extreme weather events and sea-level rise."Beyond climate change, the Sundarbans are under growing pressure from industrial developments, new roads, and greater poaching," said Professor Laurance."So, tigers are getting a double whammy -- greater human encroachment on the one hand and a worsening climate and associated sea-level rises on the other," he said.But the researchers emphasise there is still hope."The more of the Sundarbans that can be conserved -- via new protected areas and reducing illegal poaching -- the more resilient it will be to future climatic extremes and rising sea levels," said Professor Laurance."Our analyses are a preliminary picture of what could happen if we don't start to look after Bengal tigers and their critical habitats," said Dr Mukul."There is no other place like the Sundarbans left on Earth," said Professor Laurance. "We have to look after this iconic ecosystem if we want amazing animals like the Bengal tiger to have a chance of survival."
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Weather
| 2,019 |
February 6, 2019
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https://www.sciencedaily.com/releases/2019/02/190206115616.htm
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Forecast suggests Earth's warmest period on record
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The forecast for the global average surface temperature for the five-year period to 2023 is predicted to be near or above 1.0 °C above pre-industrial levels, says the Met Office. If the observations for the next five years track the forecast that would make the decade from 2014 to 2023 the warmest run of years since records began.
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Today's figures released by the Met Office include data from a number of sources including the latest publication of provisional figures for 2018 and the publication of the latest Met Office decadal forecast to 2023.Records for annual global average temperature extend back to 1850.Professor Adam Scaife, Head of Long-Range Prediction at the Met Office said: "2015 was the first year that global annual average surface temperatures reached 1.0 °C above pre-industrial levels and the following three years have all remained close to this level. The global average temperature between now and 2023 is predicted to remain high, potentially making the decade from 2014 the warmest in more than 150 years of records."Averaged over the five-year period 2019-2023, forecast patterns suggest enhanced warming is likely over much of the globe, especially over land and at high northern latitudes, particularly the Arctic region.Dr Doug Smith, Met Office Research Fellow said, "A run of temperatures of 1.0 °C or above would increase the risk of a temporary excursion above the threshold of 1.5 °C above pre-industrial levels. Predictions now suggest around a 10 per cent chance of at least one year between 2019 and 2023 temporarily exceeding 1.5 °C."Alongside this forecast, 2018 is today cited to be nominally the fourth warmest year on record globally in data released by the Met Office, at 0.91±0.1°C above the long-term pre-industrial average. It follows 2015, 2016 and 2017, which are the three warmest years in the 169-year record of the HadCRUT4 dataset.Professor Tim Osborn, director of the University of East Anglia's Climatic Research Unit, which co-produces the HadCRUT4 global temperature figures with the Met Office Hadley Centre, said: "The warmth of 2018 is in line with the long-term warming trend driven by the world's emissions of greenhouse gases."The effects of climate change are not limited to surface temperature. Warming of the climate system is seen across a range of climate indicators that build a picture of global changes occurring across the land, atmosphere, oceans and ice.The Met Office decadal forecast show that global average surface temperatures may be close to reaching 1.5 °C, but this would be a temporary exceedance rather than the climatological level of warming in the Paris 1.5 °C threshold.
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Weather
| 2,019 |
February 5, 2019
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https://www.sciencedaily.com/releases/2019/02/190205134017.htm
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New scale to characterize strength and impacts of atmospheric river storms
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A team of researchers led by Scripps Institution of Oceanography at the University of California San Diego has created a scale to characterize the strength and impacts of "atmospheric rivers," long narrow bands of atmospheric water vapor pushed along by strong winds. They are prevalent over the Pacific Ocean and can deliver to the Western United States much of its precipitation during just a few individual winter storms.
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They are the source of most of the West Coast's heaviest rains and floods, and are a main contributor to water supply. For example, roughly, 80 percent of levee breaches in California's Central Valley are associated with landfalling atmospheric rivers.The scale, described Thursday in the February 2019 The scale was developed by F. Martin Ralph, director of the Center for Western Water and Weather Extremes (CW3E) at Scripps, in collaboration with Jonathan Rutz from the National Weather Service and several other experts. It ranks atmospheric rivers from 1 to 5 and creates the categories "weak," "moderate," "strong," "extreme," and "exceptional." It uses amounts of water vapor within an atmospheric river as its basis and a period of 24 to 48 hours as its standard measurement of duration. When an AR lasts in an area for less than 24 hours, it is demoted by one category, but if it lingers for more than 48 hours, it is promoted. This approach is based on research showing that a combination of strong water vapor transport with long duration over a location, is what causes the greatest impacts. Unlike the hurricane scale, recently criticized for not representing adequately the impacts of slow-moving lower-category hurricanes, the AR scale builds in duration as a fundamental factor.The scale ranks ARs as follows:Ralph is considered a leading authority on atmospheric rivers, which were officially defined by the American Meteorological Society in 2017. Researchers have only begun to study atmospheric rivers in depth in the past two decades building on earlier research into extratropical cyclone structure and precipitation, especially in the United Kingdom. In that time, they have also come to understand how these events frequently make the difference between flood and drought years in key coastal regions around the world such as California.Ralph said that the scale could provide a crucial tool to officials with an operational need to assess flood potential in their jurisdictions before storms strike. Unlike other scales that focus primarily on damage potential, such as the Fujita scale for tornadoes or the Saffir-Simpson scale for hurricanes, the atmospheric river scale accounts not only for storms that can prove hazardous, but also for storms that can provide benefits to water supply."The scale recognizes that weak ARs are often mostly beneficial because they can enhance water supply and snow pack, while stronger ARs can become mostly hazardous, for example if they strike an area with conditions that enhance vulnerability, such as burn scars, or already wet conditions," say Ralph and co-authors in the paper appearing today in the February 2019 issue of the Coauthors of the paper include weather forecasters, such as meteorologist Jon Rutz and Chris Smallcomb of the National Weather Service (NWS)."The concept of ARs has directly benefited NWS operations in the West through better scientific understanding, more accurate precipitation forecasts, and a better vehicle for communicating impacts to our partners," said Rutz. "The AR scale is a significant step forward, providing forecasters with a tool to distinguish between primarily beneficial and primarily hazardous storms. I anticipate that this scale will be adopted and highly used."Previous analysis has shown that on the West Coast, the Oregon coast receives the most atmospheric rivers in the "extreme" range (AR Cat 4), averaging about one per year. Washington receives extreme atmospheric rivers about every two years, the Bay Area about every three years and Los Angeles every 10 years. The 1996-1997 atmospheric river that caused the largest flood damages in California since 1950 would be categorized as an "exceptional" AR storm. The strongest atmospheric river storms hitting the Southern California coast annually, typically fall in the "moderate" to "strong" range (AR Cat 2-3).When atmospheric river storms along the West Coast are predicted, the scale rankings will be updated and communicated via the CW3E website and Twitter handle. This new scale will add to data, seasonal outlooks and precipitation forecasts provided by the center as a resource to water managers, weather forecasters, emergency officials, policy makers, and others.The researchers said that the atmospheric river scale is intended as a tool to increase situational awareness ahead of a major storm in a way that reflects conditions broadly in a region of roughly 50 km size. It is not intended to represent detailed conditions on smaller spatial scales where variable topography, land surface types, and vulnerabilities vary greatly and thus modulate storm impacts."This scale enables improved awareness of the potential benefit versus hazard of a forecast AR," said co-author Michael Anderson of the California Department of Water Resources. "It can serve as a focal point for discussion between water managers, emergency response personnel and the research community as these key water supply and flood inducing storms continue to evolve in a changing climate.""Forecasters in the western U.S. have been using the concept of ARs in their forecasting for a few years now, and many have been looking for a way to distinguish beneficial from hazardous AR storms," said Rutz. "The scale was designed partly to meet this need, and it is anticipated that it will be used extensively."
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Weather
| 2,019 |
February 4, 2019
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https://www.sciencedaily.com/releases/2019/02/190204124211.htm
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Pika survival rates dry up with low moisture
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Although it has been ranked as the cutest creature in US National Parks, the American pika is tough, at home in loose alpine rocks in windswept mountain regions. Related to rabbits and hares, pikas live in cold, wet climates and high terrain, spending winters in snowy homes living off of stored grasses and other forage they have gathered, only venturing out for more when weather permits.
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Unfortunately for these adorable little mammals, they have a fairly severe sensitivity to overheating -- they die if they are exposed to temperatures above 77°F for longer than six hours. Due to their lethal threshold for heat stress, pikas are indicators of how changing environmental conditions can affect mountain-dwelling species.It might appear that the danger for pikas lies mostly with increasing temperatures and summer heat extremes. In some cases, however, decreased snowpack and lower air moisture may threaten pikas more.Vapor-pressure deficit (VPD) can be likened to air's aridity -- higher VPD is drier. VPD governs the growth of many plants that pikas depend on for food, and controls cloud formation and snow. If VPD becomes higher, it will inhibit the growth of plants that pikas depend on for food, and will shrink snow packs which they use for insulation against extreme temperature. The snowpack also stores water until springtime, when it provides water for forage plants that pikas eat.A team of researchers lead by Aaron N. Johnston of the U.S. Geological Survey sought to understand how climate change, specifically changes in snowpack and VPD, is affecting pikas. In a paper published recently in the Ecological Society of America's journal The study period included a year with record-low snowpack and high VPD (very dry air) in winter of 2014-2015, a data point that provided valuable observations of these variables' influences on the ecosystem. The researchers further studied the dynamics across differing elevations -- low, middle, and high.The results were surprisingly variable, with different dynamics acting over different elevations."We expected snowpack to be an important factor because it has many important ecological functions for pikas," said Johnston. "The effect of VPD in winter was a big surprise."At the lowest elevations, populations declined markedly. Unusually high VPD during the snow drought dried up forage plant species accustomed to moist conditions, and lack of food may have prompted malnourished pikas to forgo reproduction. Cold exposure did not appear to affect these pikas, where absence of snowpack is common because of generally warm temperatures.At middle elevations, it was cold stress, not dry air, that had the biggest effect. Along a narrow elevation band, about 1200-1500 meters, pika populations lacked a strong snowpack in which to seek shelter and insulation from extreme cold. However, it was a dip in reproduction the following year, not pika mortality in a single winter, that caused the population abundance to drop. Pikas may have even resorbed fetuses in response to the cold stress of the snow drought.At high elevations, where snow often persists for up to 7-9 months, forage came back into play as the important driver of abundances. Populations increased, having had sufficient snow cover for insulation despite a snow drought, and having benefitting from increased forage availability due to earlier snowmelt and a longer growth season for food. Pikas were able to consume and collect enough food to increase their health and ability to produce many offspring over the following winter.Given the pervasive influence of moisture on the physiology of plants and animals, the authors find the lack of previous studies on animal responses to VPD surprising."Moisture is distinct from climatic factors of temperature and precipitation that are commonly used to explain animal distributions," Johnston stated. "Incorporating moisture into species distribution models should improve ecological understanding of species and their responses to climate change."Climate-indicator species like pikas provide a number of ecosystem services and play an important role in biodiversity. Pikas serve as a food source for a number of predators, including weasels, coyotes, and birds of prey. They are also ecosystem engineers -- their foraging helps promote the diversity and distribution of various plant species and nutrients. Consequently, pika die-offs could have many lasting dire consequences for the environment and serve as a harbinger in forecasting potential climate change impacts on animal and plant life across the greater continental US.As extreme events like snow drought continue to increase in frequency, how these events and their interactions with VPD will affect animal species remains largely unexplored. Support for continued research into climate indicator species such as the pika is critically important.
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Weather
| 2,019 |
February 4, 2019
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https://www.sciencedaily.com/releases/2019/02/190204085950.htm
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Much of the surface ocean will shift in color by end of 21st century
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Climate change is causing significant changes to phytoplankton in the world's oceans, and a new MIT study finds that over the coming decades these changes will affect the ocean's color, intensifying its blue regions and its green ones. Satellites should detect these changes in hue, providing early warning of wide-scale changes to marine ecosystems.
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Writing in The researchers ran the model through the end of the 21st century and found that, by the year 2100, more than 50 percent of the world's oceans will shift in color, due to climate change.The study suggests that blue regions, such as the subtropics, will become even more blue, reflecting even less phytoplankton -- and life in general -- in those waters, compared with today. Some regions that are greener today, such as near the poles, may turn even deeper green, as warmer temperatures brew up larger blooms of more diverse phytoplankton."The model suggests the changes won't appear huge to the naked eye, and the ocean will still look like it has blue regions in the subtropics and greener regions near the equator and poles," says lead author Stephanie Dutkiewicz, a principal research scientist at MIT's Department of Earth, Atmospheric, and Planetary Sciences and the Joint Program on the Science and Policy of Global Change. "That basic pattern will still be there. But it'll be enough different that it will affect the rest of the food web that phytoplankton supports."Dutkiewicz's co-authors include Oliver Jahn of MIT, Anna Hickman of the University of Southhampton, Stephanie Henson of the National Oceanography Centre Southampton, Claudie Beaulieu of the University of California at Santa Cruz, and Erwan Monier of the University of California at Davis.The ocean's color depends on how sunlight interacts with whatever is in the water. Water molecules alone absorb almost all sunlight except for the blue part of the spectrum, which is reflected back out. Hence, relatively barren open-ocean regions appear as deep blue from space. If there are any organisms in the ocean, they can absorb and reflect different wavelengths of light, depending on their individual properties.Phytoplankton, for instance, contain chlorophyll, a pigment which absorbs mostly in the blue portions of sunlight to produce carbon for photosynthesis, and less in the green portions. As a result, more green light is reflected back out of the ocean, giving algae-rich regions a greenish hue.Since the late 1990s, satellites have taken continuous measurements of the ocean's color. Scientists have used these measurements to derive the amount of chlorophyll, and by extension, phytoplankton, in a given ocean region. But Dutkiewicz says chlorophyll doesn't necessarily have reflect the sensitive signal of climate change. Any significant swings in chlorophyll could very well be due to global warming, but they could also be due to "natural variability" -- normal, periodic upticks in chlorophyll due to natural, weather-related phenomena."An El Niño or La Niña event will throw up a very large change in chlorophyll because it's changing the amount of nutrients that are coming into the system," Dutkiewicz says. "Because of these big, natural changes that happen every few years, it's hard to see if things are changing due to climate change, if you're just looking at chlorophyll."Instead of looking to derived estimates of chlorophyll, the team wondered whether they could see a clear signal of climate change's effect on phytoplankton by looking at satellite measurements of reflected light alone.The group tweaked a computer model that it has used in the past to predict phytoplankton changes with rising temperatures and ocean acidification. This model takes information about phytoplankton, such as what they consume and how they grow, and incorporates this information into a physical model that simulates the ocean's currents and mixing.This time around, the researchers added a new element to the model, that has not been included in other ocean modeling techniques: the ability to estimate the specific wavelengths of light that are absorbed and reflected by the ocean, depending on the amount and type of organisms in a given region."Sunlight will come into the ocean, and anything that's in the ocean will absorb it, like chlorophyll," Dutkiewicz says. "Other things will absorb or scatter it, like something with a hard shell. So it's a complicated process, how light is reflected back out of the ocean to give it its color."When the group compared results of their model to actual measurements of reflected light that satellites had taken in the past, they found the two agreed well enough that the model could be used to predict the ocean's color as environmental conditions change in the future."The nice thing about this model is, we can use it as a laboratory, a place where we can experiment, to see how our planet is going to change," Dutkiewicz says.As the researchers cranked up global temperatures in the model, by up to 3 degrees Celsius by 2100 -- what most scientists predict will occur under a business-as-usual scenario of relatively no action to reduce greenhouse gases -- they found that wavelengths of light in the blue/green waveband responded the fastest.What's more, Dutkiewicz observed that this blue/green waveband showed a very clear signal, or shift, due specifically to climate change, taking place much earlier than what scientists have previously found when they looked to chlorophyll, which they projected would exhibit a climate-driven change by 2055."Chlorophyll is changing, but you can't really see it because of its incredible natural variability," Dutkiewicz says. "But you can see a significant, climate-related shift in some of these wavebands, in the signal being sent out to the satellites. So that's where we should be looking in satellite measurements, for a real signal of change."According to their model, climate change is already changing the makeup of phytoplankton, and by extension, the color of the oceans. By the end of the century, our blue planet may look visibly altered."There will be a noticeable difference in the color of 50 percent of the ocean by the end of the 21st century," Dutkiewicz says. "It could be potentially quite serious. Different types of phytoplankton absorb light differently, and if climate change shifts one community of phytoplankton to another, that will also change the types of food webs they can support. "
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Weather
| 2,019 |
January 30, 2019
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https://www.sciencedaily.com/releases/2019/01/190130133204.htm
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Extreme rainfall events are connected around the world
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An analysis of satellite data has revealed global patterns of extreme rainfall, which could lead to better forecasts and more accurate climate models.
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Extreme rainfall -- defined as the top five percent of rainy days -- often forms a pattern at the local level, for example tracking across Europe. But new research, published today in These patterns connect through the atmosphere rather than over land -- for example, extreme rainfall in Europe can precede extreme rainfall in India by around five days, without extreme rain in the countries in between.The research, led by a team at Imperial College London and the Potsdam Institute for Climate Impact Research in Germany, could help better predict when and where extreme rainfall events will occur around the world. The insights can be used to test and improve global climate models, leading to better predictions.The study additionally provides a 'baseline' for climate change studies. By knowing how the atmosphere behaves to create patterns of extreme rainfall events, scientists will be able to gain new insights into changes that may be caused by global warming.Lead author Dr Niklas Boers, from Potsdam Institute for Climate Impact Research and the Grantham Institute -- Climate Change and Environment at Imperial, said: "Uncovering this global pattern of connections in the data can improve weather and climate models.This is especially true for the emerging picture of couplings between the tropics and the European and North American regions and their consequences for extreme rainfall."This finding could also help us understand the connections between different monsoon systems and extreme events within them. I hope that our results will, in the long term, help to predict extreme rainfall and associated flash floods and landslides in northeast Pakistan, north India and Nepal. There have been several such hazards in recent years, with devastating consequences in these regions, such as the 2010 Pakistan flood."To find patterns in extreme rainfall events, the team developed a new method rooted in complex system theory to study high-resolution satellite data of rainfall. The data comes from the Tropical Rainfall Measuring Mission and covers the region between 50? North and South since 1998.By breaking the globe into a grid, the team could see where events occurred and determine how 'synchronous' they were -- a statistical measure that assesses connections even if the events did not occur at exactly the same time.The results from this 'complex network' model, analysed using our understanding of the motion of the atmosphere, revealed a possible mechanism for how the events were connected. The patterns appear to be created by Rossby waves -- wiggles in fast-flowing currents of air high in the atmosphere, known as the jet streams.Rossby waves have been connected to regular rainfall, but this study is the first to connect them to extreme rainfall event patterns. Co-author Professor Brian Hoskins, Chair of the Grantham Institute at Imperial, said: "The new technique applied to satellite data shows very surprising relationships between extreme rainfall events in different regions around the world."For example, extreme events in the South Asian Summer Monsoon are, on average, linked to events in the East Asian, African, European and North American regions. Although rains in Europe do not cause the rain in Pakistan and India, they belong to the same atmospheric wave pattern, with the European rains being triggered first."This should provide a strong test for weather and climate models and gives promise of better predictions."Co-author Jürgen Kurths, from the Potsdam Institute for Climate Impact Research, said: "This truly interdisciplinary study, which combines complex network science with atmospheric science, is an outstanding example for the great potential of the rather young field of complexity studies. As well providing insight into the spread of epidemics or information flow across networks, it can also be used to improve our understanding of extreme events in the climate system."
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Weather
| 2,019 |
January 29, 2019
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https://www.sciencedaily.com/releases/2019/01/190129124901.htm
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River levels tracked from space
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Water levels in the Mekong basin, which extends through six countries in South-East Asia, are subject to considerable seasonal fluctuations. A new model now makes it possible to compute how water levels are impacted on various sections of the river by extreme weather events such as heavy rainfall or drought over extended periods.
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To model the flow patterns of the river, with its complex network of distributaries, Claudia Klüppelberg, a professor of Mathematical Statistics at TUM, used statistical methods to link satellite data. A team at the German Geodetic Research Institute at TUM applied specially developed algorithms to raw measurement data collected from satellite missions. The new model makes it possible to extrapolate water level data for certain points to determine the levels at almost any location in the entire river system.Altimetry instruments transmit radar waves from satellites to Earth. These signals bounce back from the water surface towards the source. "By measuring the time taken by the radar waves to travel that distance, we can calculate the water levels," says Florian Seitz, a professor of Geodetic Geodynamics at TUM. "However, that is possible only where the satellite's track crosses a body of water. But for purposes of the water supply, hydrological analysis and safety issues such as the potential risk of flooding, it is equally important to know the water levels at other points."Altimetry satellites on repetitive orbits usually pass over the same points on a repeating cycle of 10 to 35 days. As a result, water level data are captured for each of these points at regular intervals. The researchers also used observations collected by an SAR altimetry satellite. Instead of following a repetitive orbit, this satellite collects data at a given point on the river just once. However, the points covered are distributed throughout the entire river system. The SAR altimetry method is also superior to conventional systems in terms of accuracy.The researchers of the involved institutes combined the different types of satellite data using a statistical method known as universal kriging. "Being able to include these additional, highly accurate measurements with a good spatial distribution in our model greatly improved the quality of the results," says Claudia Klüppelberg."The seasonal fluctuations in water levels on the Mekong, the diverse topography, and the regular flooding enabled us to test many different scenarios," says Florian Seitz. "The methods we have developed are applicable to all major river systems -- even where there are no ground stations to measure water levels."
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Weather
| 2,019 |
January 29, 2019
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https://www.sciencedaily.com/releases/2019/01/190129124827.htm
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Weather at key growth stages predicts Midwest corn yield and grain quality
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Corn is planted on approximately 90 million acres across the United States every year. With all that data, it takes months after harvest for government agencies to analyze total yield and grain quality. Scientists are working to shorten that timeline, making predictions for end-of-season yield by mid-season. However, fewer researchers have tackled predictions of grain quality, especially on large scales. A new University of Illinois study starts to fill that gap.
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The study, published in "There are several studies assessing factors influencing quality for specific genotypes or specific locations, but before this study, we couldn't make general predictions at this scale," says Carrie Butts-Wilmsmeyer, research assistant professor in the Department of Crop Sciences at U of I and co-author of the study.As corn arrives at elevators across the Midwest each season, the U.S. Grains Council takes samples to assess composition and quality for their annual summary reports, which are used for export sales. It was this comprehensive database that Butts-Wilmsmeyer and her colleagues used in developing their new algorithm."We used data from 2011 to 2017, which encompassed drought years as well as record-yielding years, and everything in between," says Juliann Seebauer, principal research specialist in U of I's Department of Crop Sciences and co-author of the study.The researchers paired the grain-quality data with 2011- 2017 weather data from the regions feeding into each grain elevator. To build their algorithm, they concentrated on the weather during three critical periods -- emergence, silking, and grain fill -- and found that the strongest predictor of both grain yield and compositional quality was water availability during silking and grain fill.The analysis went deeper, identifying conditions leading to higher oil or protein concentrations -- information that matters to grain buyers.The proportion of starch, oil, and protein in corn grain is influenced by genotype, soil nutrient availability, and weather. But the effect of weather isn't always straightforward when it comes to protein. In drought conditions, stressed plants deposit less starch in the grain. Therefore, the grain has proportionally more protein than that of plants not experiencing drought stress. Good weather can also lead to higher protein concentrations. Plenty of water means more nitrogen is transported into the plant and incorporated into proteins.In the analysis, "above-average grain protein and oil levels were favored by less nitrogen leaching during early vegetative growth, but also higher temperatures at flowering, while greater oil than protein concentrations resulted from lower temperatures during flowering and grain fill," the authors say in the study.The ability to better predict protein and oil concentrations in grain could influence global markets, considering the growing domestic and international demand for higher-protein corn for animal feed applications. With the new algorithm, it should be theoretically possible to make end-of-season yield and quality predictions weeks or months ahead of harvest simply by looking at weather patterns."Other researchers have achieved real-time yield predictions using much more complex data and models. Ours was a comparatively simple approach, but we managed to add the quality piece and achieve decent accuracy," Butts-Wilmsmeyer says. "The weather variables we found to be important in this study could be used in more complex analyses to achieve even greater accuracy in predicting both yield and quality in the future."
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Weather
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January 28, 2019
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https://www.sciencedaily.com/releases/2019/01/190128111723.htm
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Extreme weather and geopolitics major drivers of increasing 'food shocks'
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The research, published in the journal
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Lead author Richard Cottrell said extreme weather was a major cause of shocks to crops and livestock, highlighting the vulnerability of food production to climate and weather volatility."In recent decades we have become increasingly familiar with images in the media of disasters such as drought and famine around the world," Mr Cottrell said."Our study confirms that food production shocks have become more frequent, posing a growing danger to global food production."We looked at the full range of global food production systems, covering crops, livestock, fisheries and aquaculture"We found that crops and livestock are slightly more shock-prone than fisheries and aquaculture, and some regions, such as South Asia, are more frequently affected than others."While the number of food shocks fluctuates from year to year, the long-term trend shows they are happening more often."Mr Cottrell said the increasing frequency of food shocks gave people and communities less recovery time between events and eroded their resilience."Reduced recovery time hinders coping strategies such as accumulating food or assets for use during times of hardship."Combined with adverse climate conditions, conflict related shocks to food production across sub-Saharan Africa and the Middle East have led to a rise in global hunger since 2010."Land-based crop and livestock production are particularly vulnerable to extreme weather events such as drought, which are expected to become more frequent and intense with climate change."However, marine-based food production is not immune from shocks."Overfishing was responsible for 45 per cent of shocks detected in landing data, while disruptions to aquaculture production have risen faster and to a higher level than any other sector since the 1980s."Globalised trade and the dependence of many countries on food imports mean that food shocks are a global problem, and the international community faces a significant challenge to build resilience."This can be done through measures such as investing in climate-smart food systems, and building food reserves in import-dependent nations so they are better able to deal with the impact of disruption caused by problems such as climate change," Mr Cottrell said.
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Weather
| 2,019 |
January 24, 2019
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https://www.sciencedaily.com/releases/2019/01/190124115353.htm
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Major northeastern U.S. snowstorms expected to continue with climate change
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Even though climate change is expected to reduce the total amount of U.S. snowfall this century, it's unlikely to significantly rein in the most powerful nor'easters that pummel the East Coast, new research indicates.
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The study finds that smaller snowstorms that drop a few inches will diminish greatly in number by late century. But the most damaging types of storms along the Eastern Seaboard, which strike every few years or so and cause widespread disruption, will remain about as frequent in a warming world."What this research finds is almost all of the decrease in snow occurs in weaker, more nuisance-type events," said atmospheric scientist Colin Zarzycki, the author of the study. "The really crippling storms that have major regional impacts on transportation, on the economy, on infrastructure are not significantly mitigated in a warming climate.""The big nor'easters are not just going to go away."Zarzycki conducted the research as a scientist at the National Center for Atmospheric Research. He is now a professor at Pennsylvania State University in the Department of Meteorology and Atmospheric Science.The new study is part of a growing body of research into the complex ways that a warmer atmosphere will influence weather patterns and extreme weather events. Scientists have found that storms such as hurricanes and hailstorms are likely to become less frequent in the future -- but pack an even more powerful punch in those instances when they're especially intense.The study was published in Previous scientific studies have indicated that total snowfall over the course of the winter is likely to decline in coming decades. The reason, for the most part, is straightforward: more precipitation will fall as rain because of the warming influence of greenhouse gases on the atmosphere.Zarzycki wanted to take a closer look to see how warmer temperatures would affect individual nor'easters. These powerful storms can bring blizzard conditions and coastal flooding to densely populated areas, sometimes causing widespread disruption and economic damage stretching into the billions of dollars.To do so, Zarzycki turned to an existing set of advanced computer simulations of climate conditions, which scientists had created using the NCAR-based Community Earth System Model. The simulations used projections of society continuing a "business-as-usual" approach to emitting greenhouse gases, which would lead to pronounced warming this century. The simulation data set also consists of multiple ensemble members, which are realizations of the same climate but with different weather patterns that reflect the natural variability of weather. This was crucial for Zarzycki to get statistics for very rare but crippling storms.Zarzycki applied a specialized algorithm to the simulations to essentially cut out and count the number of snowstorms. This enabled him to effectively peer into future climate conditions and zero in on the impact on individual nor'easters.The results show that moderate nor'easters, which currently occur every one to two years, will decline sharply over the next few decades and become almost twice as rare by late century. But the frequency of very powerful storms that occur about once a decade, or of the most extreme storms that strike a few times per century, will be largely unchanged.The reasons have to do with a combination of factors that will occur in the future: a shorter snow season, the ability of the atmosphere to hold more water, the warming of ocean waters that fuel powerful storms, and the increased energy in the warmer atmosphere that can turbocharge storms when conditions are lined up. All of these can modify a storm's impacts in different ways."We'll have fewer storms overall in the future, but when the atmospheric conditions align they'll still pack a wallop, with incredibly heavy snowfall rates," Zarzycki said.The research also accounts for population distribution, which can highlight regional societal impacts. For example, Zarzycki found that the trajectories of future storms will generally remain the same, meaning they are about as likely as present-day storms to bear down on heavily populated areas along the coastal corridor. That's an important consideration, given that the path a snowstorm takes could lead to paralyzing one or more of the nation's most economically important cities.Zarzycki did not analyze how the mix between rain and snow may evolve in the future or what that might mean for flooding. But the paper recommends that local officials incorporate potential changes in powerful storms when planning new projects."Additional considerations are needed when developing hydrological infrastructure for water resources and flood resistance as the behavior of snowpack, snowmelt, and runoff tied to coastal storms [in the Northeast] are likely to change in the future," the paper concludes.
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Weather
| 2,019 |
January 22, 2019
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https://www.sciencedaily.com/releases/2019/01/190122104512.htm
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Near-term climate prediction 'coming of age'
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The quest for climate scientists to be able to bridge the gap between shorter-term seasonal forecasts and long-term climate projections is 'coming of age', a study shows.
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A new review paper by a team of international climate experts, including Professor Adam Scaife from the University of Exeter and the Met Office, has shown the true capabilities of near-term climate predictions, out to just a few years aheadThese improved predictions are increasingly valuable for policymakers, governments and international aid agencies to provide increased resilience to flood and drought management, as well as international disaster risk reduction.The study is published in leading research journal Professor Adam Scaife, jointly from the University of Exeter and Met Office and a lead author on the study said: "There is a lot of work still to do, but just as weather forecasts became a regular operational activity in the 20th century, we are now approaching a similar point for near term climate predictions and these are now being made at a number of scientific institutes worldwide."The new study highlights the prospects for skillful near-term climate predictions, when climate models are started from real-time observations of both the ocean and the atmosphere.Crucially, these enhanced ocean-atmosphere climate models also feature the effects of human-made greenhouse gases and natural effects, such as solar variability on climate.Yochanan Kushnir of the Lamont-Doherty Earth Observatory at Colombia University, and joint lead author of the study added: "Our paper promotes the move of near-term climate prediction from the experimental state to the practical application for the 21st century decision makers."We are convinced that with proper delivery and coaching, users of the operational product will be able to utilize this information effectively for long-term planning in a broad range of economic sectors and -- importantly -- for increasing society's resilience to climate variability and change."Developing countries, for example in sub-Saharan Africa, are expected to benefit increasingly from the boost in near-term climate prediction.Near-term climate prediction is listed as one of the Grand Challenges of the World Climate Research Programme, an international programme helping to co-ordinate global climate research.Pavel Kabat, the World Meteorological Organization's Chief Scientist and Director of Research, said: "Climate predictions at decadal time scales are produced routinely now to international standards, allowing this nascent field to develop further and to adapt to society's needs. This achievement is an outstanding example of long-standing science investment and ongoing collaboration between entities such as the World Climate Research Programme and international partners in research and national prediction centers."The authors' study shows prospects for skillful near-term prediction when coupled climate model simulations -- including those representing both the atmosphere and the oceans -- are initialized using observations from the current climate.These are further improved when incorporating the influences from human-induced climate change and natural drivers, such as solar radiation.Professor Scaife added: "An exciting prospect is that the skill of these predictions a few years ahead is similar to the skill of seasonal predictions a few months ahead, which are already widely used for planning aid and disaster risk reduction."
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Weather
| 2,019 |
January 21, 2019
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https://www.sciencedaily.com/releases/2019/01/190121153636.htm
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Greenland ice melting four times faster than in 2003
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Greenland is melting faster than scientists previously thought -- and will likely lead to faster sea level rise -- thanks to the continued, accelerating warming of the Earth's atmosphere, a new study has found.
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Scientists concerned about sea level rise have long focused on Greenland's southeast and northwest regions, where large glaciers stream iceberg-sized chunks of ice into the Atlantic Ocean. Those chunks float away, eventually melting. But a new study published Jan. 21 in the "Whatever this was, it couldn't be explained by glaciers, because there aren't many there," said Michael Bevis, lead author of the paper, Ohio Eminent Scholar and a professor of geodynamics at The Ohio State University. "It had to be the surface mass -- the ice was melting inland from the coastline."That melting, which Bevis and his co-authors believe is largely caused by global warming, means that in the southwestern part of Greenland, growing rivers of water are streaming into the ocean during summer. The key finding from their study: Southwest Greenland, which previously had not been considered a serious threat, will likely become a major future contributor to sea level rise."We knew we had one big problem with increasing rates of ice discharge by some large outlet glaciers," he said. "But now we recognize a second serious problem: Increasingly, large amounts of ice mass are going to leave as meltwater, as rivers that flow into the sea."The findings could have serious implications for coastal U.S. cities, including New York and Miami, as well as island nations that are particularly vulnerable to rising sea levels.And there is no turning back, Bevis said."The only thing we can do is adapt and mitigate further global warming -- it's too late for there to be no effect," he said. "This is going to cause additional sea level rise. We are watching the ice sheet hit a tipping point."Climate scientists and glaciologists have been monitoring the Greenland ice sheet as a whole since 2002, when NASA and Germany joined forces to launch GRACE. GRACE stands for Gravity Recovery and Climate Experiment, and involves twin satellites that measure ice loss across Greenland. Data from these satellites showed that between 2002 and 2016, Greenland lost approximately 280 gigatons of ice per year, equivalent to 0.03 inches of sea level rise each year. But the rate of ice loss across the island was far from steady.Bevis' team used data from GRACE and from GPS stations scattered around Greenland's coast to identify changes in ice mass. The patterns they found show an alarming trend -- by 2012, ice was being lost at nearly four times the rate that prevailed in 2003. The biggest surprise: This acceleration was focused in southwest Greenland, a part of the island that previously hadn't been known to be losing ice that rapidly.Bevis said a natural weather phenomenon -- the North Atlantic Oscillation, which brings warmer air to West Greenland, as well as clearer skies and more solar radiation -- was building on man-made climate change to cause unprecedented levels of melting and runoff. Global atmospheric warming enhances summertime melting, especially in the southwest. The North Atlantic Oscillation is a natural -- if erratic -- cycle that causes ice to melt under normal circumstances. When combined with man-made global warming, though, the effects are supercharged."These oscillations have been happening forever," Bevis said. "So why only now are they causing this massive melt? It's because the atmosphere is, at its baseline, warmer. The transient warming driven by the North Atlantic Oscillation was riding on top of more sustained, global warming."Bevis likened the melting of Greenland's ice to coral bleaching: Once the ocean's water hits a certain temperature, coral in that region begins to bleach. There have been three global coral bleaching events. The first was caused by the 1997-98 El Niño, and the other two events by the two subsequent El Niños. But El Niño cycles have been happening for thousands of years -- so why have they caused global coral bleaching only since 1997?"What's happening is sea surface temperature in the tropics is going up; shallow water gets warmer and the air gets warmer," Bevis said. "The water temperature fluctuations driven by an El Niño are riding this global ocean warming. Because of climate change, the base temperature is already close to the critical temperature at which coral bleaches, so an El Niño pushes the temperature over the critical threshold value. And in the case of Greenland, global warming has brought summertime temperatures in a significant portion of Greenland close to the melting point, and the North Atlantic Oscillation has provided the extra push that caused large areas of ice to melt."Before this study, scientists understood Greenland to be one of the Earth's major contributors to sea-level rise -- mostly because of its glaciers. But these new findings, Bevis said, show that scientists need to be watching the island's snowpack and ice fields more closely, especially in and near southwest Greenland.GPS systems in place now monitor Greenland's ice margin sheet around most of its perimeter, but the network is very sparse in the southwest, so it is necessary to densify the network there, given these new findings."We're going to see faster and faster sea level rise for the foreseeable future," Bevis said. "Once you hit that tipping point, the only question is: How severe does it get?"
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Weather
| 2,019 |
January 19, 2019
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https://www.sciencedaily.com/releases/2019/01/190119095707.htm
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Local drivers of amplified Arctic warming
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The Artic experienced an extreme heat wave during the February 2018. The temperature at the North Pole has soared to the melting point of ice, about 30-35 degrees (17-19 Celsius) above normal. There have also been recent studies, indicating the mass of Arctic glaciers has declined significantly since the 1980's by more than 70%. These sudden climate changes affected not just the Arctic regions, but also the water, food, and energy security nexus throughout the globe. This is why climate scientists from around the world are paying increasing attention to this accelerated warming pattern, commonly referred to as 'Arctic Amplification'.
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An international team of researchers, including Professor Sarah Kang and DoYeon Kim in the School of Urban and Environmental Engineering at UNIST, has unveiled that local greenhouse gas concentrations appear to be attributable to Arctic Amplification.Published in the November 2018 issue of Long-term observations of surface temperatures show an intensified surface warming in Canada, Siberia, Alaska and in the Arctic Ocean relative to global mean temperature rise. Arctic Amplification is consistent with computer models, simulating the response to increasing greenhouse gas concentrations. However, the underlying physical processes for the intensified warming still remain elusive.Using complex computer simulations, the scientists were able to disprove previously suggested hypotheses, that emphasized the role of transport of heat from the tropics to the poles as one of the key contributors to the amplified warming in the Arctic."Our study clearly shows that local carbon dioxide forcing and polar feedbacks are most effective in Arctic amplification compared to other processes," says Assistant Project Leader Malte F. Stuecker, the corresponding author of the study.Increasing anthropogenic carbon dioxide (COIn addition to these factors, heat can be transported into the Arctic by winds. "We see this process for instance during El Niño events. Tropical warming, caused either by El Niño or anthropogenic greenhouse emissions, can cause global shifts in atmospheric weather patterns, which may lead to changes in surface temperatures in remote regions, such as the Arctic," said Kyle Armour, co-author of the study and professor of Atmospheric Sciences and Oceanography at the University of Washington.Moreover, global warming outside the Arctic region will also lead to an increase in Atlantic Ocean temperatures. Ocean currents, such as the Gulf Stream and the North Atlantic drift can then transport the warmer waters to the Arctic ocean, where they could melt sea ice and experience further amplification due to local processes.To determine whether tropical warming, atmospheric wind and ocean current changes contribute to future Arctic Amplification, the team designed a series of computer model simulations. "By comparing simulations with only Arctic COIn the tropics -- fueled by high temperature and moisture -- air can easily move up to high altitudes, meaning the atmosphere is unstable. In contrast, the Arctic atmosphere is much more stable with respect to vertical air movement. This condition enhances the CO"Our computer simulations show that these changes in the vertical atmospheric temperature profile in the Arctic region outweigh other regional feedback factors, such as the often-cited ice-albedo feedback" says Malte Stuecker.The findings of this study highlights the importance of Arctic processes in controlling the pace at which sea-ice will retreat in the Arctic Ocean. The results are also important to understand how sensitive polar ecosystems, Arctic permafrost and the Greenland ice-sheet will respond to Global Warming.
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Weather
| 2,019 |
January 18, 2019
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https://www.sciencedaily.com/releases/2019/01/190118110835.htm
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Mangrove patches deserve greater recognition no matter the size
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Governments must provide stronger protection for crucial small mangrove patches, is the call led by scientists at international conservation charity ZSL (Zoological Society of London), which hosts the IUCN SSC Mangrove Specialist Group, in a letter published in
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With nearly 35% of mangroves lost from around the world since the 1980s, primarily due to coastal development, the future loss of seemingly small mangrove patches to new construction projects such as airports or aquaculture is extremely worrying for coastal communities and Critically Endangered wildlife like the pygmy three-toed sloth (Bradypus pygmaeus) and green sawfish (Pristis zijsron) that are protected by, and reliant on, these habitats.Large swathes of mangroves in Southeast Asia, such as in the Philippines, have been cleared to make way for aquaculture, mainly shrimp and fish ponds. Elsewhere, in the Maldives, mangroves are being cleared to make way for a controversial new airport to be built. Here, despite assurances being made that only 30% of mangroves would be directly affected as a result, almost 70% may have already been destroyed.Mangroves offer vital ecosystem services to local communities, providing food, coastal protection from extreme weather events, fisheries support and key natural carbon storage facilities. They clean water by trapping sediments and pollutants and help mitigate the impacts of storm surges and tsunamis on coastal communities, particularly in vulnerable low-lying island nations.Despite warnings from leading scientists about the dire ramifications of losing mangroves, the conversion and degradation of mangrove forests for infrastructure or agriculture still occur -- especially for smaller mangrove patches.The letter states that the continued loss of small patches of mangroves could result in the disconnect of habitats, meaning natural wildlife corridors used by species to move freely throughout the landscape could be lost. This could generate new barriers for wildlife being able to adapt to the effects of climate change, as well as low-lying island communities becoming increasingly vulnerable to extreme weather patterns such as typhoons during monsoon seasons.Dr David Curnick, Post-doctoral Researcher at ZSL's Institute of Zoology and member of the IUCN SSC Mangrove Specialist Group said: "Given the recent Intergovernmental Panel on Climate Change's projections, we simply cannot afford to lose more mangrove forests, irrespective of their size."All too often mangroves are regarded as irrelevant swamps or wastelands -- yet they're incredibly important ecosystems. Globally, yes, mangrove conservation is being looked at, but it's these smaller patches of mangroves in remote areas that need greater recognition."We need governments to move away from policy decisions that prioritise large areas and short-term local political gains, and instead adopt a more well-rounded long-term vision, ensuring the value of smaller mangrove patches are appreciated and safeguarded."Though Mangroves are covered under international agreements including the Convention on Biological Diversity (CBD), the United Nations Framework Convention on Climate Change (UNFCCC) and Convention for the Protection of World Cultural and Natural Heritage -- these are only recommendations and thus mangrove forests are still one of the most severely threatened and undervalued ecosystems on Earth.The ecosystem services provided by mangroves are conservatively estimated at around £1.2 billion (US $1.6 billion) globally, suggesting that no matter their size, they are key to meeting commitments like the Paris Climate Agreement.ZSL hosts the IUCN SSC Mangrove Specialist Group and supports projects around the globe helping to rehabilitate mangrove forests using 'Community-based Mangrove Rehabilitation approaches in countries like the Philippines, where over 50% of mangroves have been lost. Over a four-year period, close to 100,000 mangroves have been planted, with the rehabilitation of 107.8 hectares of mangrove forest well underway.
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Weather
| 2,019 |
January 10, 2019
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https://www.sciencedaily.com/releases/2019/01/190110141811.htm
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Oceans are warming even faster than previously thought
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Berkeley -- Heat trapped by greenhouse gases is raising ocean temperatures faster than previously thought, concludes an analysis of four recent ocean heating observations. The results provide further evidence that earlier claims of a slowdown or "hiatus" in global warming over the past 15 years were unfounded.
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"If you want to see where global warming is happening, look in our oceans," said Zeke Hausfather, a graduate student in the Energy and Resources Group at the University of California, Berkeley, and co-author of the paper. "Ocean heating is a very important indicator of climate change, and we have robust evidence that it is warming more rapidly than we thought."Ocean heating is critical marker of climate change because an estimated 93 percent of the excess solar energy trapped by greenhouse gases accumulates in the world's oceans. And, unlike surface temperatures, ocean temperatures are not affected by year-to-year variations caused by climate events like El Nino or volcanic eruptions.The new analysis, published Jan. 11 in Assuming a "business-as-usual" scenario in which no effort has been made to reduce greenhouse gas emissions, the Coupled Model Intercomparison Project 5 (CMIP5) models predict that the temperature of the top 2,000 meters of the world's oceans will rise 0.78 degrees Celsius by the end of the century. The thermal expansion caused by this bump in temperature would raise sea levels 30 centimeters, or around 12 inches, on top of the already significant sea level rise caused by melting glaciers and ice sheets. Warmer oceans also contribute to stronger storms, hurricanes and extreme precipitation."While 2018 will be the fourth warmest year on record on the surface, it will most certainly be the warmest year on record in the oceans, as was 2017 and 2016 before that," Hausfather said. "The global warming signal is a lot easier to detect if it is changing in the oceans than on the surface."The four studies, published between 2014 and 2017, provide better estimates of past trends in ocean heat content by correcting for discrepancies between different types of ocean temperature measurements and by better accounting for gaps in measurements over time or location."The Intergovernmental Panel on Climate Change's (IPCC) Fifth Assessment Report, published in 2013, showed that leading climate change models seemed to predict a much faster increase in ocean heat content over the last 30 years than was seen in observations," Hausfather said. "That was a problem, because of all things, that is one thing we really hope the models will get right.""The fact that these corrected records now do agree with climate models is encouraging in that is removes an area of big uncertainty that we previously had," he said.A fleet of nearly 4,000 floating robots drift throughout the world's oceans, every few days diving to a depth of 2000 meters and measuring the ocean's temperature, pH, salinity and other bits of information as they rise back up. This ocean-monitoring battalion, called Argo, has provided consistent and widespread data on ocean heat content since the mid-2000s.Prior to Argo, ocean temperature data was sparse at best, relying on devices called expendable bathythermographs that sank to the depths only once, transmitting data on ocean temperature until settling into watery graves.Three of the new studies included in the "Scientists are continually working to improve how to interpret and analyze what was a fairly imperfect and limited set of data prior to the early 2000s," Hausfather said. "These four new records that have been published in recent years seem to fix a lot of problems that were plaguing the old records, and now they seem to agree quite well with what the climate models have produced."
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Weather
| 2,019 |
January 10, 2019
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https://www.sciencedaily.com/releases/2019/01/190110141735.htm
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A new way to measure solar panel degradation
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Despite many benefits and relative popularity as a renewable energy source, eventually, the sun does set on even the best solar panels. Over time, solar cells face damage from weather, temperature changes, soiling, and UV exposure. Solar cells also require inspections to maintain cell performance levels and reduce economic losses.
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So, how does one inspect panels in real time, in a way that is both cost-effective and time-efficient? Parveen Bhola, a research scholar at India's Thapar Institute of Engineering and Technology, and Saurabh Bhardwaj, an associate professor at the same institution, spent the last few years developing and improving statistical and machine learning-based alternatives to enable real-time inspection of solar panels. Their research found a new application for clustering-based computation, which uses past meteorological data to compute performance ratios and degradation rates. This method also allows for off-site inspection.Clustering-based computation is advantageous for this problem because of its ability to speed up the inspection process, preventing further damage and hastening repairs, by using a performance ratio based on meteorological parameters that include temperature, pressure, wind speed, humidity, sunshine hours, solar power, and even the day of the year. The parameters are easily acquired and assessed, and can be measured from remote locations.Improving PV cell inspection systems could help inspectors troubleshoot more efficiently and potentially forecast and control for future difficulties. Clustering-based computation is likely to shed light on new ways to manage solar energy systems, optimizing PV yields, and inspiring future technological advancements in the field."The majority of the techniques available calculate the degradation of PV (photovoltaic) systems by physical inspection on site. This process is time-consuming, costly, and cannot be used for the real-time analysis of degradation," Bhola said. "The proposed model estimates the degradation in terms of performance ratio in real time."Bhola and Bhardwaj worked together before and developed the model to estimate solar radiation using a combination of the Hidden Markov Model and the Generalized Fuzzy Model.The Hidden Markov Model is used to model randomly changing systems with unobserved, or hidden states; the Generalized Fuzzy Model attempts to use imprecise information in its modeling process. These models involve recognition, classification, clustering, and information retrieval, and are useful for adapting PV system inspection methods.The benefits of real-time PV inspection go beyond time-sensitive and cost-efficient measures. This new, proposed method can also improve current solar power forecasting models. Bhola noted that the output power of a solar panel, or set of solar panels, could be forecasted with even greater accuracy. Real-time estimation and inspection also allows for real-time rapid response."As a result of real-time estimation, the preventative action can be taken instantly if the output is not per the expected value," Bhola said. "This information is helpful to fine-tune the solar power forecasting models. So, the output power can be forecasted with increased accuracy."
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Weather
| 2,019 |
January 9, 2019
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https://www.sciencedaily.com/releases/2019/01/190109110058.htm
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Two billion birds migrate over Gulf Coast
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A new study combining data from citizen scientists and weather radar stations is providing detailed insights into spring bird migration along the Gulf of Mexico and how these journeys may be affected by climate change. Findings on the timing, location, and intensity of these bird movements are published in the journal
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"We looked at data from thousands of eBird observers and 11 weather radar stations along the Gulf Coast from 1995 to 2015," says lead author Kyle Horton, an Edward W. Rose Postdoctoral Fellow at the Cornell Lab of Ornithology. "We calculated that an average of 2.1 billion birds crosses the entire length the Gulf Coast each spring as they head north to their breeding grounds. Until now, we could only guess at the overall numbers from surveys done along small portions of the shoreline."eBird is the Cornell Lab's worldwide online database for bird observation reports. Sightings from bird watchers helped researchers translate their radar data into estimates of bird numbers. Weather radar detects birds in the atmosphere in a standardized way over time and over a large geographical area.The radar data reveal when birds migrate and what routes they take. The timing of peak spring migration was consistent over 20 years along the 1,680-mile coastline. But the researchers found that the 18-day period from April 19 to May 7 was the busiest -- approximately one billion birds passed over the Gulf Coast in that time span. Not all locations were equally busy, with key hotspots showing significantly higher levels of activity.The highest activity, with 26,000 birds per kilometer of airspace each night, was found along the west Texas Gulf Coast," says Horton. "That region had 5.4 times the number of migrants detected compared with the central and eastern Gulf Coast from Louisiana to Florida." The data show Corpus Christi and Brownsville as having the highest level of migration traffic along the western coast of Texas.Knowing where and when peak migration occurs means efforts can be made to turn off lights and wind turbines, which are known threats to migratory birds.Migration timing is also critical for birds. Although migration has evolved in the past as climates changed, the current rate of change may be too rapid for birds to keep pace. This study shows that the earliest seasonal movements are starting sooner, advancing by about 1.5 days per decade, though peak activity timing hasn't changed, which may be cause for concern. These findings provide important baseline information that will allow scientists to assess the long-term implications of climate change for migratory birds."If birds aren't changing their migration timing fast enough to match the timing for plants and insects, that's alarming," Horton says. "They may miss out on abundant resources on their breeding grounds and have less reproductive success."Scientists from the Cornell Lab of Ornithology, the University of Oxford, the Smithsonian Migratory Bird Center, the University of Delaware, and the University of Oklahoma conducted this research.
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Weather
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December 28, 2018
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https://www.sciencedaily.com/releases/2018/12/181228091650.htm
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Reliable tropical weather pattern to change in a warming climate
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Every month or two, a massive pulse of clouds, rainfall and wind moves eastward around the Earth near the equator, providing the tropics their famous thunderstorms.
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This band of recurring weather, first described by scientists in 1971, is called the Madden-Julian Oscillation. It has profound effects on weather in distant places, including the United States. Atmospheric scientists have long studied how the Madden-Julian Oscillation modulates extreme weather events across the globe, from hurricanes to floods to droughts.As human activities cause the Earth's temperature to increase, reliable, well-studied weather patterns like the Madden-Julian Oscillation will change too, say researchers at Colorado State University.Eric Maloney, professor in the Department of Atmospheric Science, has led a new study published in Their analysis reveals that while the Madden-Julian Oscillation's precipitation variations are likely to increase in intensity under a warmer climate, wind variations are likely to increase at a slower rate, or even decrease. That's in contrast to the conventional wisdom of a warming climate producing a more intense Madden-Julian Oscillation, and thus an across-the-board increase in extreme weather."In just looking at precipitation changes, the Madden-Julian Oscillation is supposed to increase in strength in a future climate," Maloney said. "But one of the interesting things from our study is that we don't think this can be generalized to wind as well."Atmospheric science relies on weather patterns like the Madden-Julian Oscillation to inform weather prediction in other areas of Earth. For example, atmospheric rivers, which are plumes of high atmospheric water vapor that can cause severe flooding on the U.S. west coast, are strongly modulated by certain phases of the Madden-Julian Oscillation.According to Maloney's work, the Madden-Julian Oscillation's impact on remote areas may gradually decrease. Degradation in the oscillation's wind signal may thus diminish meteorologists' ability to predict extreme weather events. In particular, preferential warming of the upper troposphere in a future, warmer climate is expected to reduce the strength of the Madden-Julian Oscillation circulation.Maloney and colleagues hope to continue studying the Madden-Julian Oscillation using a broader set of climate models to be used in the next Intergovernmental Panel on Climate Change assessment.
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Weather
| 2,018 |
December 26, 2018
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https://www.sciencedaily.com/releases/2018/12/181226132839.htm
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European wheat lacks climate resilience
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The climate is not only warming, it is also becoming more variable and extreme. Such unpredictable weather can weaken global food security if major crops such as wheat are not sufficiently resilient -- and if we are not properly prepared.
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A group of European researchers, including Professor Jørgen E. Olesen from the Department of Agroecology at Aarhus University, has found that current breeding programmes and cultivar selection practices do not provide the needed resilience to climate change.- The current breeding programmes and cultivar selection practices do not sufficiently prepare for climatic uncertainty and variability, the authors state in a paper recently published in PNAS (Proceedings of the National Academy of Sciences). Not only that -- the response diversity of wheat on farmers' fields in most European countries has worsened in the past five to fifteen years, depending on country.Researchers predict that greater variability and extremeness of local weather conditions will lead to reduced yields in wheat and increased yield variability.- Needless to say, decreased yields are not conducive to food security, but higher yield variability also poses problems. It can lead to a market with greater speculation and price volatility. This may threaten stable access to food by the poor, which in turn can enhance political instability and migration, Jørgen E. Olesen points out.The researchers base their assessments on thousands of yield observations of wheat cultivars in nine European countries for qualifying how different cultivars respond to weather. The researchers identified the variation of wheat response diversity on farmers' fields and demonstrated the relation to climate resilience.The yield responses of all cultivars to different weather events were relatively similar within northern and central Europe, and within southern European countries -- the latter particularly with regard to durum wheat. There were serious gaps in wheat resilience across all Europe, especially with regard to yield performance under abundant rain.- The lack of response diversity can pose serious problems with regard to food security. Therefore, farmers, breeders, and dealers in seeds and grain need to pay more attention to the diversity of cultivars grown, warns Professor Jørgen E. Olesen.Wheat is an important staple food crop in Europe and is the leading source of plant protein in our diet globally, so it is important to ensure that we have climate-resilient wheat cultivars on hand.Rain, drought, heat or cold at vulnerable times during the growing season can seriously damage yields. Wheat yield is generally sensitive to even a few days of exposure to waterlogging and to wet weather that favours disease. In addition, heat stress rather than drought sensitivity appears to be a limiting factor for adaptation of wheat to climate change in Europe.The dominant approach of adapting crops to climate change by tailoring genotypes to the most likely long-term change is likely insufficient. The capacity of a single crop variety to maintain good yield performance under climatic variability and extremes is limited, but diversity in responses to critical weather events can effectively enhance climate resilience. Therefore, a set of cultivars with diverse responses to critical weather conditions is prerequisite to promoting crop climate resilience.The authors stress that the need for climate resilience of staple food crops such as wheat must be better articulated. Increased awareness could foster governance of resilience through research and breeding programmes, incentives and regulation.
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Weather
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December 21, 2018
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https://www.sciencedaily.com/releases/2018/12/181221123737.htm
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Forecasters may be looking in wrong place when predicting tornadoes
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Weather forecasters may be looking in the wrong place when working to issue tornado warnings, new research led by Ohio University has demonstrated.
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Historically, there have been a wide number of conflicting theories about how tornadoes form, but the most widely accepted was that they form from the top down, based on work done from the 1970s through the 1990s. For the first time, new observational evidence shows that they actually form from the ground up, which could have a profound impact on the way tornado warnings are issued in the future. It's the first time these hypotheses have been able to be evaluated observationally, thanks to a modern radar system that collects data very rapidly."We need to reconsider the paradigms that we have to explain tornado formation, and we especially need to communicate this to forecasters who are trying to make and issue warnings," said Dr. Jana Houser, assistant professor of meteorology at Ohio University and co-author of the new study. "Based on our results, it does not look like you are going to really ever be finding strong evidence of a tornado descending, so we need to stop making that a priority in our forecasting strategies."A team led by Houser demonstrated that tornadoes actually form at the ground and move up rapidly, contrary to the long-held hypothesis that most tornadoes form at cloud level and descend to touch the earth. This evidence, the first of its kind, was gathered after Houser observed an EF5 tornado in May 2011; this work began during her doctoral work at the University of Oklahoma. Those findings were subsequently confirmed through observations from several other tornadoes, including a very compelling visual and radar analysis of the deadly El Reno tornado of May 2013."The coupled visual and near-surface radar observations from the El Reno 2013 case enable an analysis of the tornadogenesis process that has never before been obtained, providing a missing link in the story of tornado formation: the rotation associated with the tornado was clearly present at the surface first," Houser said. She presented the findings to the American Geophysical Union at a conference Dec. 14.The findings indicate that a tornado-strength vortex can be active on the ground for a minute or more before the deeper tornadic column forms and is picked up by conventional radar. However, tornado warnings are issued based on radar readings that pick up vortex signatures at or above cloud level."We need to strategize how we're issuing warnings a little bit differently. The way we're doing it, we're never going to get an improvement on our warning system," Houser said.The challenge is in getting those kinds of readings quickly. Conventional radar can't get ground-level readings over a broad area because objects in the way, such as hills, buildings and trees, disrupt the data, and they collect data slowly. Houser's data came from the University of Oklahoma's Rapid-scan, X-band, polarimetric mobile radar (RaXPol). Radar observations of the wind field were used to track tornadic signatures in the core of the storm. In the 2013 El Reno tornado, observations showed evidence of a tornado that was only visible in radar data less than 20 meters above the ground, but nowhere else, at the beginning. The next elevation angle above showed no tornado-strength rotation.In all four cases, none of the tornadoes formed from the top down. Three formed from the bottom up, and one contracted almost simultaneously over the depth of the column being observed.The tornadoes formed in 30 to 90 seconds, making the prospect of forecasting tornadoes with 100 percent accuracy seem bleak.In the largest tornado the team studied, the deadly 2013 El Reno tornado, video documentation showed that a funnel cloud was visible for one minute and 40 seconds before the development of a radar-derived, vertically-continuous vortex. That storm ultimately had a width of 2.6 miles and winds exceeding 300 miles per hour. When radar data were re-examined, it was determined that the only sign of tornadic-strength rotation that existed at the beginning occurred in the lowest elevation data, less than 20 meters above the ground, which was present for about one minute before the tornado's formation and persisted until the rest of the tornado developed. This provided the first confirmation that this tornado began at the ground and was able to persist at that level for almost two minutes before the formation of the deeper vortex.Houser said that by better understanding the mechanisms of tornado formation, it's possible forecasters can generate short-term, high-resolution models of storms just hours before they occur to determine their likelihood of producing a tornado, efforts already being pursued by the National Weather Service and the National Severe Storms Laboratory.Other efforts could include stationary, ground-based radar systems, though there would need to be a blanket of them to prove effective, as well as storm spotters relaying visual responses to forecasters."If we can get a concrete picture of what's happening in tornado formation, we'll have better insight into the processes and mechanisms in predicting tornadoes," Houser said.
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Weather
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December 21, 2018
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https://www.sciencedaily.com/releases/2018/12/181221123735.htm
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Wildlife struggle to cope with extreme weather
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The mass death of flying foxes in extreme heat in North Queensland last month underscores the importance of University of Queensland wildlife research released today.
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The UQ research sheds light on how various species have responded to major climate events.A study led by UQ School of Earth and Environmental Science researcher Dr Sean Maxwell has synthesised more than 70 years of research to quantify the responses of various species."The growing frequency and intensity of extreme weather events such as cyclones, droughts and floods is causing unpredictable and immediate changes to ecosystems and obstructing existing management efforts," Dr Maxwell said."The deaths of up to one third of Australia's spectacled flying foxes in an extreme heatwave north of Cairns in November comes in the wake of our research, and is a stark illustration of the importance of the study."Some of the negative responses we found were quite concerning, including more than 100 cases of dramatic population declines and 31 cases of local population extinction following an extreme event."Populations of critically endangered bird species in Hawaii, such as the palia, have been annihilated due to drought, and populations of lizard species have been wiped out due to cyclones in the Bahamas."Cyclones were the most prevalent extreme event for birds, fish, plants and reptiles, while mammals and amphibians were most responsive to drought events, with drought leading to 12 cases of major population decline in mammals.Drought also led to 13 cases of breeding declines in bird populations and 12 cases of changes in the composition of invertebrate communities.UQ Centre for Biodiversity and Conservation Science director Professor James Watson said the detailed information would help inform ecosystem management."The research clearly shows species will respond, often negatively, to extreme events," Professor Watson said."As climate change continues to ensure extreme climate and weather events are more and more common, we now need to act to ensure species have the best chance to survive."Wherever possible, high quality and intact habitat areas should be retained, as these are the places where species are most resilient to increasing exposure to extreme events."
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Weather
| 2,018 |
December 20, 2018
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https://www.sciencedaily.com/releases/2018/12/181220104627.htm
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First detection of rain over the ocean by navigation satellites
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In order to analyse climate change or provide information on natural hazards, for example, it is important for researchers to gather knowledge about rain. Better knowledge of precipitation and its distribution could, for example, help protect against river flooding. On land, monitoring stations can provide data by collecting precipitation. At sea, it's not so easy.
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A new approach by a team around Milad Asgarimehr, who works in the GFZ section for Space Geodetic Techniques and at the Technical University of Ber-lin, together with researchers from the Earth System Research Laboratory of the National Oceanic and Atmospheric Administration of the USA (NOAA) and the University of Potsdam, uses information contained in radar signals from GNSS satellites (Global Navigation Satellite System) to detect rain over the sea. The technology is called GNSS Reflectometry. It is an innovative satellite re-mote sensing method with a broad spectrum of geophysical applications. As-garimehr and his colleagues have now published their results in the journal According to the researchers, the new approach could help to monitor atmos-pheric precipitation better than before. Asgarimehr: "Our research can serve as a starting point for the development of an additional rain indicator. We can pro-vide precipitation information using GNSS Reflectometry with unprecedented temporal resolution and spatial coverage.""GNSS are 'all-weather navigation systems'," explains Asgarimehr. "A long-held basic assumption was therefore that their signals are composed in such a way that they are not noticeably attenuated by clouds or typical precipitation in the atmosphere and therefore cannot detect precipitation." The new study there-fore uses a different effect to detect rain over the sea: The roughness of the sea surface.That surface is 'rough' mainly because winds create waves on it. The strength of the satellite signals reflected by the surface is inversely proportional to their roughness: the more and the stronger the waves, the weaker the reflected signal. Recently, researchers were able to prove that it is possible to determine the wind speed over the oceans from measurements of the roughness of its surface.Raindrops falling on a sea surface also change its roughness. Milad Asgarimehr and the team around him asked themselves: "Can GNSS Reflectometry detect precipitation over oceans?" This is also the title of their recently published study. If the answer is yes, GNSS Reflectometry satellites could detect rain almost like an observer watching raindrops disturb the mirror image of the moon on the surface of a lake at night. However, there is one major difference: unlike moonlight, GNSS signals are able to penetrate the clouds.During the analysis of data from the navigation satellite TDS-1 (TechDemoSat-1), Asgarimehr found evidence that rain is detectable over the oceans if the winds are not too strong. However, his research still lacked a theoretical foun-dation. "For a long time it was thought that GNSS Reflectometry measure-ments should be insensitive to the small-scale surface roughness caused by raindrops on the sea surface," explains Asgarimehr. But the publication of a new theoretical model in 2017 provided a plausible estimate of the physics of the scattering of radar signals on a sea surface disturbed by weak winds.
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Weather
| 2,018 |
December 17, 2018
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https://www.sciencedaily.com/releases/2018/12/181217101801.htm
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Building a better weapon against harmful algal blooms
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Predicting and pinpointing which farming practices are most likely to protect against environmental harm is a complex proposition, and researchers at The Ohio State University are working to fine-tune the tools that could help farmers and others prevent harmful algal blooms.
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This week at the American Geophysical Union (AGU) fall meeting in Washington, D.C, a team of scientists from The Ohio State University shared early results from a trio of studies that aim to improve models designed to guide agricultural practices for reducing the risk of nitrogen and phosphorus farm runoff. Such runoff leads to the growth of toxic algae in waterways.Basic models for predicting the consequences of various decisions, such as when to apply fertilizer, are available but they must be refined in order to ensure reliability and gain the trust of interested parties, including farmers and environmental protection organizations, said Jay Martin, a professor of ecological engineering at Ohio State.Asmita Murumkar, a postdoctoral researcher at Ohio State, said her work is beginning to illuminate how the timing of fertilizer application intersects with heavy rains to contribute to nutrient runoff. She's working with the Ohio Applicator Forecast, a tool that uses National Weather Service data to assign risk estimates to applying fertilizer at various times.Murumkar is hopeful that her research will help quantify what impact the tool would have on the environment under different scenarios- say if a quarter of farmers in the Maumee River watershed used it, or half."We want to better understand how much phosphorus runoff it would reduce in the region," Martin said, adding that there's plenty of evidence that individual farm practices impact runoff from those farms, but less evidence in terms of larger-scale estimates."We know from our previous work that fertilizer timing is important, but we want to be able to look across the whole Lake Erie Basin and know best-case and worst-case scenarios and this modeling will help address that," he said.Margaret Kalcic, assistant professor in Ohio State's Food, Agricultural and Biological Engineering Department, said farmers are encouraged to follow the "Four Rs" for right time, source, amount and place when applying fertilizer."But 'right' is not clearly defined, and our team is working to provide our partners in Ohio, including farmers, advocates and policymakers, with better answers," Kalcic said.Added Martin, "There's more subtlety here than just watching the weather and the ground moisture and we're trying to determine the best solutions that support agricultural production and environmental protection."Grey Evenson, a postdoctoral researcher at Ohio State, will present initial findings on his work to identify the best data to use in modeling, so that it offers a more accurate picture of what is happening in fields and adjacent waterways."We don't want to underestimate -- or overestimate -- the value of these best management practices. For instance, some practices may produce greater benefits than we give them credit for in the model -- such as improving soil health, which leads to better water retention," Evenson said.Added Kalcic, "A lot of this work is about tuning existing models. By improving the quality of information we put into them we have greater confidence in the information that comes out of them." She said that there are many questions about the larger environmental impacts of practices such as no-till farming, which is generally thought of as environmentally friendly."We know that no-till is good for preventing soil erosion, but there are still uncertainties about its effects on water quality in the region," Kalcic said.Graduate student Anna Apostel discussed a third project, in which she's manipulating various parameters in one model to try to determine how reliable -- or not -- the model is. The long-term goal is to move toward more-robust estimates of how practices contribute to water quality.Martin said adjusting parameters so that magnitudes of processes better match reality and data from observations in the field is a critical part of improving model performance."We want to adjust our equations to better represent reality," Apostel said.The overarching goal of all the work, the researchers said, is to have models that better align with what the researchers have observed in field experiments but that can look at the issues on a broad, regional level."We know that if you build a bad model it's not going to help anybody make any decisions," Kalcic said."We really want to build trust in truly useful models that will help policymakers, farmers and others. The worst thing would be that people trust models that are telling them the entirely wrong message," she said.
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Weather
| 2,018 |
December 12, 2018
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https://www.sciencedaily.com/releases/2018/12/181212144625.htm
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Climate change imperils Midwest ag production
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A new Cornell University-led study shows that Midwest agriculture is increasingly vulnerable to climate change because of the region's reliance on growing rain-fed crops.
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Ariel Ortiz-Bobea, assistant professor of applied economics and management, set out to assess the impact extreme weather is having on agricultural productivity in the United States. While previous studies have looked at the vulnerability of individual field crops, which make up one-third of the country's agricultural output, researchers haven't addressed the whole scope of agricultural production, including livestock, at the national level."We're trying to get a big picture idea of what is going on," said Ortiz-Bobea. "The data captures every state's agriculture over the past 50 years. If you see in the aggregate data that something big is happening, this really captures massive processes that are affecting many people at the same time."The resulting paper, "Growing Climatic Sensitivity of U.S. Agriculture Linked to Technological Change and Regional Specialization" published in To get this panoramic snapshot, Ortiz-Bobea and his team used state-level measures of agricultural productivity that capture how inputs -- such as seeds, feed, fertilizer, equipment and herbicides -- are converted into economic outputs. The researchers mapped that information against nearly 50 years' worth of climate data from 1960 through 2004, essentially seeing what would happen if weather was treated as an additional input.The results show a clear escalation in climate sensitivity in the Midwest between two distinct time periods. In the 1960s and '70s, a 2-degree Celsius rise in temperature during the summer resulted in an 11 percent drop in productivity. After the 1983, however, the same rise in temperature caused productivity to drop 29 percent.While these damaging summer conditions usually only occur six percent of the time, the researchers indicate that an additional 1-degree Celsius warming would more than quadruple their frequency to roughly one of every four years."Losing almost half your profit every four years? That's a big loss," said Ortiz-Bobea, a fellow at Cornell's Atkinson Center for a Sustainable Future.One of the reasons the Midwest is growing more vulnerable to drastic climate variations is because its agriculture industry is increasingly specialized in crop production, like nonirrigated cereal and oilseed crops."Specialization in crop production is a compounding factor," said Ortiz-Bobea, who collaborated on the paper with Erwin Knippenberg, a Cornell doctoral student in applied economics and management, and Robert G. Chambers of the University of Maryland."Most of the agriculture in the Midwest is corn and soybeans. And that's even more true today than it was 40 years ago," Ortiz-Bobea said. "That has implications for the resilience to climate of that region, because they're basically putting all their eggs in one basket, and that basket is getting more sensitive."
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Weather
| 2,018 |
December 12, 2018
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https://www.sciencedaily.com/releases/2018/12/181212121857.htm
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Record-wet and record-dry months increased in regions worldwide
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More and more rainfall extremes are observed in regions around the globe -- triggering both wet and dry records, a new study shows. Yet there are big differences between regions: The central and Eastern US, northern Europe and northern Asia have experienced heavy rainfall events that have led to severe floods in recent past. In contrast, most African regions have seen an increased frequency of months with a lack of rain. The study is the first to systematically analyze and quantify changes in record-breaking monthly rainfall events from all over the globe, based on data from roughly 50,000 weather stations worldwide. Climate change from fossil fuel greenhouse gases has long been expected to disturb rainfall patterns.
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"We took a close look at observed monthly rainfall data -- if it's not just a few days but several weeks that are record wet, this can accumulate over time and lead to large river floods, or to droughts if it is record dry," says lead author Jascha Lehman from the Potsdam Institute for Climate Impact Research (PIK). The impacts on people's livelihoods in the affected regions can be huge, ranging from flooded houses to endangered food security due to large-scale agricultural losses.The US has so far seen an increase of record wet months by more than 25 percent in the Eastern and central parts over the period 1980-2013. Argentina and bordering countries have experienced an increase of 32 percent. In central and northern Europe the increase is between 19 and 37 percent. In the Asian part of Russia the increase is around 20 percent, while South East Asia shows an increase of about 10 percent.The scientists ran strict tests for the statistical significance of observed changes. Therefore, they so far see significant changes in dry extremes just in Africa south of the Sahara and in the Sahel zone where dry records have increased by up to 50 percent. "This implies that approximately one out of three record-dry months in this regions would not have occurred without long-term climate change," says co-author Dim Coumou from the Institute for Environmental Studies (IVM) at Vrije Universiteit Amsterdam. "A central conclusion from our study is that, generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records -- this largely fits the patterns that scientists expect from human-caused climate change."The scientists compared observed wet and dry rainfall extremes to the number of extremes that would be expected in a climate without long-term changes. "We checked for new records -- monthly rainfall values that have never been observed before in a given region since the beginning of systematic measurements more than a hundred years ago." Of course one expects to see some rainfall records simply due to natural variability. "Normally, record weather events occur by chance and we know how many would happen in a climate without warming," explains Jascha Lehmann. "It's like throwing a dice: on average, one out of six times you get a six. But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often with severe impacts for society and the environment.""It is worrying that we see significant increases of such extremes already at just one degree global warming," adds Lehmann. "Right now, governments from countries all over the world meet at the UN climate summit -- if they do not agree on solutions to limit warming to well below 2 degrees, we're headed for 3-4 degrees within this century. Physics tells us that this would boost rainfall extremes even further."
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Weather
| 2,018 |
December 12, 2018
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https://www.sciencedaily.com/releases/2018/12/181212093320.htm
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Declining snowpack over Western US mapped at a finer scale
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Researchers have now mapped exactly where in the Western U.S. snow mass has declined since 1982.
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The research team mapped the changes in snow mass from 1982 to 2016 onto a grid of squares 2.5-miles on a side over the entire contiguous U.S.A person could practically find the trend for their neighborhood, said first author Xubin Zeng, a University of Arizona professor of hydrology and atmospheric sciences. Grid size for previous studies was about 40 miles on a side, he said."This is the first time anyone has assessed the trend over the U.S. at the 2.5-mile by 2.5-mile pixel level over the 35-year period from 1982 to 2016," Zeng said. "The annual maximum snow mass over the Western U.S. is decreasing."In the Eastern U.S., the researchers found very little decrease in snow mass.Even in snowy regions of the West, most of the squares did not have a significant decrease in snow. However, some parts of the Western U.S. have had a 41 percent reduction in the yearly maximum mass of snow since 1982.UA co-author Patrick Broxton said, "The big decreases are more often in the mountainous areas that are important for water supplies in the West."Snow mass is how much water it contains, which is important in regions where winter snows and subsequent snow melt contribute substantially to water resources. Snow melt contributes to groundwater and to surface water sources such as the Colorado River.Snow is also important for winter sports and the associated tourism, which is a multi-billion-dollar industry in the U.S.If all the squares in the Western U.S. that had a 41 percent reduction in snow mass were added up, the combined area would be equal in size to South Carolina, said Zeng, who holds the Agnese N. Haury Chair in Environment. He and his team looked at the interannual and multidecadal changes in snow mass for the contiguous U.S.Zeng's team also found over the period 1982-2016, the snow season shrank by 34 days on average for squares that, if combined, would equal the size of Virginia."The shortening of the snow season can be a late start or early ending or both," Zeng said. "Over the Western U.S. an early ending is the primary reason. In contrast, in the Eastern U.S. the primary driver is a late beginning."Temperature and precipitation during the snow season also have different effects in the West compared with the East, the researchers found.In the West, the multidecadal changes in snow mass are driven by the average temperature and accumulated precipitation for the season. The changes in the Eastern U.S. are driven primarily by temperature.The paper, "Snowpack Change from 1982 to 2016 Over Conterminous United States," by Zeng, Broxton and their co-author Nick Dawson of the Idaho Power Company in Boise, Idaho, is scheduled for publication in Previous estimates of interannual-to-multidecadal changes in snow mass used on-the-ground, or point, measurements of snow height and snow mass at specific stations throughout the contiguous U.S.One such network of data is the National Weather Service Cooperative Observer Program (COOP), in which more than 10,000 volunteers take daily weather observations at specific sites throughout the U.S.The other is the U.S. Department of Agriculture's SNOwpack TELemetry, or SNOTEL, network, an automated system that collects snowpack and other climatic data in the mountains of the Western U.S. However, for many locations, such measurements are unavailable.Zeng and his colleagues used an innovative method to combine data collected by COOP and SNOTEL with a third data set called PRISM that gives temperature and precipitation data over all of the lower 48 states and is also based on on-the-ground measurements.The result is a new data set that provides daily information about snow mass and snow depth from 1982 to the present for the entire contiguous U.S.Developing the new dataset has allowed the UA-led research team to examine the changes in temperature, precipitation and snow mass from 1982 to 2016 for every 2.5-mile by 2.5-mile square in the contiguous U.S, as well as to study how snow can affect weather and climate."Snow is so reflective that it reflects a lot of the sunlight away from the ground. That affects air temperature and heat and moisture exchanges between the ground and the atmosphere," said Broxton, an associate research scientist in the UA School of Natural Resources and the Environment.Zeng is now working with NASA to figure out a way to use satellite measurements to estimate snow mass and snow depth.NASA and the UA's Agnese Nelms Haury Program in Environment and Social Justice funded the research.
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Weather
| 2,018 |
December 10, 2018
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https://www.sciencedaily.com/releases/2018/12/181210151857.htm
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How will the winds of climate change affect migratory birds?
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Under future climate scenarios, changing winds may make it harder for North American birds to migrate southward in the autumn, but make it easier for them to come back north in the spring. Researchers from the Cornell Lab of Ornithology came to this conclusion using data from 143 weather radar stations to estimate the altitude, density, and direction birds took during spring and autumn migrations over several years. They also extracted wind data from 28 different climate change projections in the most recent report from the Intergovernmental Panel on Climate Change (IPCC). Their findings were published today in the journal
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"We combined these data to estimate how wind assistance is expected to change during this century under global climate change," explains lead author Frank La Sorte, a Cornell Lab of Ornithology scientist. "This matters for migratory birds because they use more energy flying into headwinds. But they get a nice boost from tailwinds so they can conserve energy during flight."La Sorte and co-authors project that winds from the south are expected to become stronger by the end of the century during both spring and fall migration periods. Winds from the west may be stronger during spring migration and slightly weaker during the fall. Westerly winds are much more variable overall and harder to predict because they are tied to erratic fluctuations in the high altitude jet stream. Wind changes will be most pronounced in the central and eastern portions of the continent.With an assist from stronger tailwinds during spring migration, birds would likely arrive in better condition on their northern breeding grounds with better odds of survival. Their fall migration flights into stronger headwinds would drain more energy. If headwinds are too strong, birds may choose not to fly at all on a particular night, throwing off the timing of their migrations."The thing to remember about these projected wind changes is that they will not occur in isolation," La Sorte says. "There will be other global change factors for birds to contend with, including changes in temperatures, rainfall, and land cover."Some birds may be able to adapt because the expected wind changes are likely to happen gradually. Studies also show that migratory birds already adjust their migration strategy under current conditions, altering their headings to compensate for winds that push them from their intended flight path."The bottom line is that some climate change effects could be negative for migratory birds, and some might even be positive, at least during a specific phase of their migration," says La Sorte. "There's an awful lot of uncertainty because both climate and migration are complex systems that can intersect in many different ways."
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December 10, 2018
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https://www.sciencedaily.com/releases/2018/12/181210115626.htm
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A glimmer of hope for the world's coral reefs
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The future of the world's coral reefs is uncertain, as the impact of global heating continues to escalate. However, according to a study published today in
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"Dead corals don't bleach for a second time. The north lost millions of heat-sensitive corals in 2016, and most of the survivors were the tougher species. As a result of bleaching, the mix of species is changing very rapidly," said lead author Prof Terry Hughes, Director of the Australian Research Council Centre of Excellence for Coral Reef Studies (Coral CoE), headquartered at James Cook University."We were astonished to find less bleaching in 2017, because the temperatures were even more extreme than the year before," he said.The new research highlights the extent of damage, or "geographic footprint" of multiple coral bleaching events across the 2,300 km length of the world-heritage listed area.The back-to-back heatwaves bring the total number of mass bleaching events on the Great Barrier Reef to four over the past two decades (in 1998, 2002, 2016 and 2017). The scientists found that only 7% of the Great Barrier Reef escaped bleaching entirely since 1998, and after the 2017 event, 61% of reefs have now been severely bleached at least once."We found, using the National Oceanic and Atmospheric Administration's (NOAA) satellite-based coral bleaching tools, that corals in the north of the Great Barrier Reef were exposed to the most heat stress in 2016. A year later, the central region saw the most prolonged heating," said co-author Dr Mark Eakin, from NOAA's Coral Reef Watch program, in Maryland, USA.The southern third of the Great Barrier Reef was cooler in both years due to local weather conditions, and escaped with only minor bleaching."It's only a matter of time before we see another mass-bleaching event, triggered by the next marine heatwave, driven by global heating," said co-author Dr Andrew Hoey of Coral CoE at James Cook University. "One of the worst possible scenarios is we'll see these southern corals succumb to bleaching in the near future.""The outcome in 2017 depended on the conditions experienced by the corals one year earlier. We called that 'ecological memory,' and show that these repeating events are now acting together in ways that we didn't expect," said Prof Hughes."We've never seen back-to-back mass coral bleaching before on the Great Barrier Reef, in two consecutive summers. The combined footprint has killed close to half of the corals on two-thirds of the world's largest reef system," said Dr Hoey."We need urgent global action on greenhouse emissions to save the world's coral reefs. Australia should be -- but regrettably isn't -- at the forefront of tackling global heating," said Prof Hughes.
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December 6, 2018
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https://www.sciencedaily.com/releases/2018/12/181206114740.htm
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Atmospheric scientists find causes of firenado in deadly Carr Fire
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A destructive fire-generated vortex -- a massive stream of rising, spinning, smoke, ash and fire -- that topped out at 17,000 feet above the earth, accelerated the Carr fire that killed eight people and devastated a widespread area in the Redding, California region in July 2018. The vortex, a little-observed atmospheric phenomena, was spinning with the power of a class three tornado, which earned it the name of Firenado.
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Atmospheric scientist Neil Lareau at the University of Nevada, Reno has authored a paper in the scientific journal "This paints a clear picture of the sequence of events leading to the vortex development and intensification," Lareau said. "This sequence suggests the Carr Fire vortex may qualify as pyro-genetic tornado, and not merely a tornado-strength fire-generated vortex."In his study, satellite and radar observations document the evolution of the vortex revealing similarities to tornado dynamics. A key factor in the vortex formation was the development of a fire-generated ice-topped cloud (known as a pyro-cumulonimbus) which reached as high as 39,000 ft. The development of the cloud helped stretch the underlying column of air, concentrating the rotation near the surface and causing the tornado strength winds, estimated at 143 mph, the strength of an EF-3 tornado.Radar data show that the vortex formed along the fire perimeter and within a pre-existing region of wind shear immediately following rapid vertical development of the convective plume, which grew from four to eight miles high in just 15 minutes. The plume development was fueled by the onset of the pyro-cumulonimbus cloud, a process similar to the development of an ordinary thunderstorm. It is this link to the cloud aloft that distinguishes the Carr fire vortex from more frequently observed fire-thirls, which tend to be smaller and less intense. The only other documented case of a "firenado" is during the Canberra Firestorm of 2003 in New South Wales, AustraliaThe data in the study came from National Weather Service NEXRAD radars located at Beale Air Force Base, in northern California, Eureka, California and Medford, Oregon. While radar data has been used to study many other wildfires with pyro-cumulonimbus clouds, this is the first instance of NEXRAD radars observing the structure and evolution of a tornadic fire-generated vortex itself.Other factors contributing to the firenado include:The Carr Fire, which burned in Shasta and Trinity Counties, started July 23 after a tire blew out on a trailer and the rim made sparks on the pavement. It went on to burn 230,000 acres -- 359 square miles -- making it the seventh largest fire in California history. It was 100 percent contained by August 30.The fire resulted in eight fatalities and destroyed 1,079 residences. Following ignition, the fire was initially terrain driven, spreading uphill from July 23 to July 25. Then, on July 26, the fire became wind-driven, advancing rapidly eastward and downhill into the western suburbs of Redding. The fire jumped the Sacramento River, and on the evening of July 26 the large fire-generated vortex formed along the northeastern flank of the fire. The fire-generated vortex was directly related to four deaths, numerous injuries and substantive loss of property."With the impacts from this fire, a discussion and studies are warranted about the potential to warn for future tornado-strength vortices," Lareau, an assistant professor in the Physics Department of the College of Science, said. "In this case, the availability of high resolution radar and satellite observations provide advance indications for vortex formation such that watches, or even warnings, may have been possible."In the future, Lareau said, the operational meteorological and fire-fighting communities might develop routines to carefully inspect radar data for evidence of shear or rotation in wildfire plumes, and satellite data for indications of fire-cloud formations and storms.Lareau's research specializes in mountain weather and wildfire plume dynamics and examines atmospheric dynamics across a range of scales. Other specific research topics includes, boundary-layer and cloud interactions, mountain valley cold air pools and synoptic-scale storm tracks.
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December 3, 2018
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https://www.sciencedaily.com/releases/2018/12/181203150459.htm
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Uneven rates of sea level rise tied to climate change
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The pattern of uneven sea level rise over the last quarter century has been driven in part by human-caused climate change, not just natural variability, according to a new study.
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The findings suggest that regions of the world where seas have risen at higher than average rates -- including the Eastern Seaboard of the United States and the Gulf of Mexico -- can expect the trend to continue as the climate warms.The study, published today in the "By knowing that climate change is playing a role in creating these regional patterns, we can be more confident that these same patterns may linger or even intensify in the future if climate change continues unabated," Fasullo said. "With sea levels projected to rise a couple of feet or more this century on average, information about expected regional differences could be critical for coastal communities as they prepare."The research was funded by the National Science Foundation, which is NCAR's sponsor, the NASA Sea Level Change Team, and the U.S. Department of Energy.For the study, Fasullo and Nerem, both members of the NASA Sea Level Change Team, analyzed the satellite altimetry sea level record, which includes measurements of sea surface heights stretching back to 1993. They mapped global average sea level rise as well as how particular regions deviated from the average.For example, the oceans surrounding Antarctica and the U.S. West Coast have had lower-than-average sea level rise, while the U.S. East Coast and Southeast Asia, including the Philippines and Indonesia, have experienced the opposite. In some parts of the world, the rate of local sea level rise has been as much as twice the average.Regional differences in sea level rise are influenced by where heat is stored in the ocean (since warm water expands to fill more space than cold water) and how that heat is transported around the globe by currents and wind. Uneven sea level rise is also influenced by ice sheets, which lose mass as they melt and shift the gravitational forces affecting regional sea surface height.Natural shifts in ocean cycles -- including the Pacific Decadal Oscillation, a pattern of sea surface temperatures similar to El Niño but longer lasting -- are therefore known to affect sea levels. So scientists were not surprised to find that as the ocean rises, it rises unevenly. But it's been difficult to say whether these natural cycles were the dominant influence on regional differences.To investigate the role of climate change, the scientists turned to two sets of climate model runs, known as "large ensembles": one created using the NCAR-based Community Earth System Model and one created using the Earth System Model at the National Oceanic and Atmospheric Administration. These large ensembles -- many model simulations by the same model, describing the same time period -- allow researchers to disentangle natural variability from the impacts of climate change. With enough runs, these impacts can be isolated even when they are relatively small compared to the impacts from natural variability.The climate models suggest that in regions that have seen more or less sea level rise than average, as much as half of that variation may be attributed to climate change. The scientists also found that the impacts from climate change on regional sea level rise sometimes mimic the impacts from natural cycles."It turns out the sea level rise response to climate change in the Pacific resembles what happens during a particular phase of the Pacific Decadal Oscillation," Fasullo said. "This explains why it's been so difficult to determine how much of the pattern was natural or not, until now."The research findings have implications for local officials, who are interested in improved forecasts of sea level rise for the areas they oversee. In the past, forecasters have had to rely on the global rate of change -- about 3 millimeters a year and accelerating -- and knowledge of the uneven regional impacts associated with continued melting of the ice sheets covering Greenland and Antarctica.The findings add the possibility that the regional patterns of sea level rise tied to climate change can also be included, because the models predict that the regional patterns observed in the satellite measurements will continue into the future."We now have a new tool -- long-term satellite altimeter measurements -- that we can use to help stakeholders who need information for specific locations," said Nerem, a fellow of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder and a professor of aerospace engineering.
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November 28, 2018
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https://www.sciencedaily.com/releases/2018/11/181128192143.htm
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Researchers rise to challenge of predicting hail, tornadoes three weeks in advance
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People living in Kansas, Nebraska and other states in the Plains are no strangers to tornadoes and hail storms -- among the most costly and dangerous severe weather threats in the United States.
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Meteorologists and computer models do a good job forecasting severe thunderstorm activity up to a week in advance. Scientists can also read long-term, seasonal signals of severe weather months in advance.But there's a middle ground -- a prediction lead time of about 2 to 5 weeks -- that's sorely lacking in current forecasting capabilities.In a new paper in "When the Madden-Julian Oscillation is active, it is capable of setting up atmospheric patterns that are favorable for severe weather across the United States over the next several weeks," explained Cory Baggett, research scientist in atmospheric science and the paper's lead author. "We have found that an active Madden-Julian Oscillation, which periodically goes around the equator in 30 to 60 days, is a really good source of predictability on these subseasonal time scales." Atmospheric scientists typically consider "subseasonal" to mean about three weeks to three months in advance.Weather forecasting weeks in advance cannot pinpoint where individual tornadoes or hail storms will occur, Baggett explained, but the researchers have shown they can forecast expected environmental conditions that are favorable for the formation of severe thunderstorms. That includes atmospheric instability and rotational vertical wind shear.Using available datasets, researchers looked at what the Madden-Julian Oscillation was doing about three weeks ahead of severe weather in the Plains and southeastern United States, during the typical severe-weather months of March through June. They used 37 years of data to cross-validate their predictions.They found "forecasts of opportunity" where they were able to make skillful predictions of severe weather activity about 60 percent to 70 percent of the time. Meteorologists would consider this rate of success "great," according to Sam Childs, a Ph.D. student in atmospheric science who co-authored the work."We're judging ourselves against climatology," Childs said. "If we predicted normal thunderstorm activity, we would be right about 50 percent of the time. Three weeks out, we're getting it right about 2-1." They also found consistently stronger ability to forecast hail and tornado activity during certain phases of the Madden-Julian Oscillation.To understand whether this new method of predicting severe weather would be useful to forecasters, the researchers hope they can transition the work to operational experts who could test it out. "In essence, these forecasts of opportunity would allow a forecaster to better alert the public of a period in which severe weather may be more likely a few weeks in advance," Childs said."I think we were all surprised at how good some of our forecasts were," he added. "That's motivation enough to carry forward, so that we might be able to have more useful forecasting products in that coveted 2-to-5-week lead time."
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November 26, 2018
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https://www.sciencedaily.com/releases/2018/11/181126142822.htm
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Extreme heat increasing in both summer and winter
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A new study shows extreme heat events both in the summer and in the winter are increasing across the U.S. and Canada, while extreme cold events in summer and winter are declining.
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A new study in the in The new study found both relative and absolute extreme heat events have increased across the US and Canada since 1980. This upward trend is greatest across the southern US, especially in the Ozarks and southern Arizona, as well as northern Quebec. That means there are more extremely hot days during the summer as well as more days that are considered extremely hot for the time of year, like abnormally warm days in the winter.The new research also found both relative and absolute extreme cold events are decreasing, most notably in Alaska and Northern Canada, along with patches along the US Atlantic coast. In these areas, there are fewer instances of temperatures that are extremely cold either compared to the normal range, like in winter, or for the time of year, like unusually cold days in the summer.Global mean surface temperature, the most frequently cited indicator of climate change, has been steadily increasing since the 1970s. However, temperature extremes pose a greater ecological risk to many species than average warming, according to the study's authors.The new study is one of the first to explore relative extreme temperature events, which are changing more rapidly than absolute temperature extremes, and can have important implications for the environment, agriculture and human health, according to Scott Sheridan, professor in the department of geography at Kent State University and lead author of the new study."Typically for this kind of research we look at the highest temperatures in the summer and lowest temperatures in the winter. But we've also seen that extreme temperatures that are really anomalous for the time of year can have a high impact -- these relative extremes are important and underappreciated," he said.To investigate how extreme temperature events have been changing over time, Sheridan and his co-author conducted a climatology of cold and heat events, both absolute and relative, for North America, followed by an analysis of how they have changed from 1980-2016.Relative extreme temperature events are changing faster than absolute extreme events, and often occur outside of seasonal norms, according to the new study. In the eastern half of the US, relative extreme heat events occur as early as mid-winter into early spring. Out-of-season extreme temperatures can cause early thaws in mild winters or catch vulnerable populations unprepared and unacclimated.Across parts of the Arctic, extreme cold events have become almost entirely nonexistent and increasingly difficult to identify, according to the researchers."Relative temperature anomalies can trigger what are called phenological mismatches, where a mismatch in the temperature and the season can cause trees to bloom too early and birds and insects to migrate before there is appropriate food," Sheridan said.Most notable is the highly anomalous warm event in March 2012, which included persistent mid-summer warmth in multiple locations. The event produced a 'false spring' in which vegetation prematurely left dormancy, so that it was not prepared for subsequent frosts, leading to large agricultural losses in certain areas, according to the researchers.There is some evidence that early-season heat events are more hazardous to humans than heat events later in the season. When people are not acclimatized to hotter temperatures, they are more vulnerable to negative health impacts, especially the elderly, infants, young children, and people with chronic health problems or disabilities, according to the researchers.The study clearly underlines the importance of not just looking at high temperatures in the summer but also looking at relative temperatures, said Kristie Ebi, professor of Environmental and Occupational Health Sciences at the University of Washington, who was not involved in the study."Using information generated in the study on regional patterns in extreme weather events, particularly relative extremes in temperature, early warnings could be issued that include information on what people can do to protect themselves and to protect crops and ecosystems," Ebi said.
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November 25, 2018
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https://www.sciencedaily.com/releases/2018/11/181125113728.htm
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New federal climate assessment for U.S. released
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A new federal report finds that climate change is affecting the natural environment, agriculture, energy production and use, land and water resources, transportation, and human health and welfare across the U.S. and its territories.
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Volume II of the Fourth National Climate Assessment (NCA4), released Nov. 23, 2018 by the United States Global Change Research Program (USGCRP -- NOAA is one of 13 federal agencies that contributed significantly to the Fourth National Climate Assessment.Human health and safety, our quality of life, and the rate of economic growth in communities across the U.S. are increasingly vulnerable to the impacts of climate change.The cascading impacts of climate change threaten the natural, built and social systems we rely on, both within and beyond the nation's borders.Societal efforts to respond to climate change have expanded in the last five years, but not at the scale needed to avoid substantial damages to the economy, environment, and human health over the coming decades.Without substantial and sustained global efforts to reduce greenhouse gas emissions and regional initiatives to prepare for anticipated changes, climate change is expected to cause growing losses to American infrastructure and property and impede the rate of economic growth over this century.Rising temperatures, extreme heat, drought, wildfire on rangelands and heavy downpours are expected to increasingly challenge the quality and quantity of U.S. crop yields, livestock health, price stability and rural livelihoods.Changes in the quality and quantity of fresh water available for people and the environment are increasing risks and costs to agriculture, energy production, industry and recreation.Climate change will transform coastal regions by the latter part of this century, with ripple effects on other regions and sectors. Many communities should expect higher costs and lower property values from sea level rise.Climate change threatens the health and well-being of the American people by causing increasing extreme weather, changes to air quality, the spread of new diseases by insects and pests, and changes to the availability of food and water.To access the report and find background information, visit the USGCRP website:
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November 20, 2018
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https://www.sciencedaily.com/releases/2018/11/181120125922.htm
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Responses of waterbirds to climate change is linked to their preferred wintering habitats
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A new scientific article shows that 25 European waterbird species can change their wintering areas depending on winter weather. Warm winters allow them to shift their wintering areas northeastwards, whereas cold spells push birds southwestwards. Species wintering in deep waters show the fastest long-term change: their abundances have shifted annually about 5 km northeastwards in the past 24 years.
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A recent collaborative study between 21 European countries provides new insights into how waterbirds respond to the changes in winter weather conditions at large scale. The study shows that waterbirds respond to both year-to-year and long-term changes in winter weather conditions, which is evident by the changes in local abundances during winter."Our study highlights that not all waterbirds respond equally to changes in weather conditions. Species preferring shallow and deep water are responding fastest to annual variation in temperature, whereas farmland species like geese, show weak responses," says Diego Pavón-Jordán from the Helsinki Lab of Ornithology at Finnish Museum of Natural History and leading author of this study.In addition to the year-to-year variation, the study also shows that there is a long-term shift of the centre of the wintering population of species preferring deep waters, which has been progressively moving northeastwards during the 1990s and 2000s. The centre of the wintering population of species preferring shallow waters moved northeastwards during the 1990s and early 2000s but southwestwards after mid-2000s, coinciding with several consecutive harsh winters in Europe."According to the latest IPCC report released in October 2018 winters will become milder in the near future, which will definitely affect abundances of waterbirds across Europe. There will likely be to local extinctions in some wetlands at the southern edge of the distribution of many species, and colonisations of new wetlands in the northern edge of the distribution," says Aleksi Lehikoinen head of the Helsinki Lab of Ornithology at the Finnish Museum of Natural History.Increased variability in winter weather conditions reported by the IPCC can also cause large year-to-year fluctuations in abundances, pushing and pulling individuals north and south along the migration flyway. All these changes in distribution areas and abundances of waterbirds create challenges to protect and monitor species. For instance species may not winter any more inside certain protected areas since climatic conditions may have become unfavourable in the region.
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November 16, 2018
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https://www.sciencedaily.com/releases/2018/11/181116110643.htm
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Half of the world's annual precipitation falls in just 12 days
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Currently, half of the world's measured precipitation that falls in a year falls in just 12 days, according to a new analysis of data collected at weather stations across the globe.
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By century's end, climate models project that this lopsided distribution of rain and snow is likely to become even more skewed, with half of annual precipitation falling in 11 days.These results are published in Previous studies have shown that we can expect both an increase in extreme weather events and a smaller increase in average annual precipitation in the future as the climate warms, but researchers are still exploring the relationship between those two trends."This study shows how those two pieces fit together," said Angeline Pendergrass, a scientist at the National Center for Atmospheric Research (NCAR) and the lead author of the new study. "What we found is that the expected increases happen when it's already the wettest -- the rainiest days get rainier."The findings, which suggest that flooding and the damage associated with it could also increase, have implications for water managers, urban planners, and emergency responders. The research results are also a concern for agriculture, which is more productive when rainfall is spread more evenly over the growing season.The research was supported by the U.S. Department of Energy and the National Science Foundation, which is NCAR's sponsor.Scientists who study extreme precipitation -- and how such events may change in the future -- have used a variety of metrics to define what qualifies as "extreme." Pendergrass noticed that in some cases the definitions were so broad that extreme precipitation events actually included the bulk of all precipitation.In those instances, "extreme precipitation" and "average precipitation" became essentially the same thing, making it difficult for scientists to understand from existing studies how the two would change independently as the climate warms.Other research teams have also been grappling with this problem. For example, a recent paper tried to quantify the unevenness of precipitation by adapting the Gini coefficient, a statistical tool often used to quantify income inequality, to instead look at the distribution of rainfall.Pendergrass wanted to find something even simpler and more intuitive that could be easily understood by both the public and other scientists. In the end, she chose to quantify the number of days it would take for half of a year's precipitation to fall. The results surprised her."I would have guessed the number would be larger -- perhaps a month," she said. "But when we looked at the median, or midpoint, from all the available observation stations, the number was just 12 days."For the analysis, Pendergrass worked with Reto Knutti, of the Institute for Atmospheric and Climate Science in Zurich, Switzerland. They used data from 185 ground stations for the 16 years from 1999 through 2014, a period when measurements could be validated against data from the Tropical Rainfall Measuring Mission (TRMM) satellite. While the stations were dispersed globally, the majority were in North America, Eurasia, and Australia.To look forward, the scientists used simulations from 36 of the world's leading climate models that had data for daily precipitation. Then they pinpointed what the climate model projections for the last 16 years of this century would translate to for the individual observation stations.They found that total annual precipitation at the observation stations increased slightly in the model runs, but the additional precipitation did not fall evenly. Instead, half of the extra rain and snow fell over just six days.This contributed to total precipitation also falling more unevenly than it does today, with half of a year's total precipitation falling in just 11 days by 2100, compared to 12 in the current climate."While climate models generally project just a small increase in rain in general, we find this increase comes as a handful of events with much more rain and, therefore, could result in more negative impacts, including flooding," Pendergrass said. "We need to take this into account when we think about how to prepare for the future."The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.
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November 14, 2018
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https://www.sciencedaily.com/releases/2018/11/181114120319.htm
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Climate control of Earth's critical zone
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We know less about the ground beneath our feet than we do about the surface of Mars, but new research by University of Colorado Boulder geoscientists shines a light on this hidden world from ridgetops to valley floors and shows how rainfall shapes the part of our planet that is just beyond where we can see.
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Earth is popularly known as the "third rock from the sun," yet hard rock is rare at the ground surface. Scientists have dubbed the vegetation, soil and water-storing debris that hides Earth's rocky interior from view the "critical zone." The name honors the fact that this zone is simultaneously essential to life and is shaped by living organisms. The character of the critical zone -- particularly its depth -- controls how groundwater is stored and released to streams.Groundwater provides the water supplies that are the lifeblood of agriculture and industry in the nation, and indeed around the world. But groundwater itself is not passive. It reacts with the rock along its path, and in so doing both chemically transforms the rock and picks up dissolved minerals and nutrients.The researchers were inspired to study the fundamental differences between two National Science Foundation-supported Critical Zone Observatories (CZOs). In the Boulder Creek CZO in the Colorado Front Range, fresh rock can be found beneath a thin layer of soil and broken rock that evenly mantles hillsides. In the Calhoun CZO in the South Carolina piedmont, fresh rock is far below the surface, and the critical zone billows thickly under ridge crests and thins under valley bottoms. And the soils of Colorado are gray-brown and rocky, in contrast to the red clays of South Carolina.The CU Boulder researchers set out to understand why this life-sustaining and water-storing blanket of soil and the underlying weathered rock vary so much from one place to another. Co-authors included Distinguished Professor Robert S. Anderson of CU Boulder's Department of Geological Sciences, President's Teaching Scholar Professor Harihar Rajaram of CU Boulder's Department of Civil, Environmental, and Architectural Engineering, and Professor Suzanne P. Anderson of CU Boulder's Department of Geography."Our goal was to create a model to explain why these differences occur," said Suzanne Anderson.The researchers focused on one of the most obvious differences between the two sites: the weather. They built a numerical model to test whether the much greater rainfall in the southeast could explain the great differences in the depth of weathering. In the model, rainwater is tracked as it seeps through the landscape, and causes rock minerals to weather (or transform) into clay. Because weathering processes are slow, it was necessary to include soil formation and erosion as well."Weathering of bedrock may be the most important geologic process, since it produces the soil we depend on for our existence," says Richard Yuretich, director of the NSF Critical Zone Observatories program, which funded the research.The results, published today in a special issue of the journal In other words, the model succeeds in explaining the drastic differences in these landscapes. The connectivity of the system captivated the research team."It's fascinating how simple patterns in critical zone thickness respond to climate, to erosion, and undoubtedly to processes that we haven't considered yet," said Suzanne Anderson, who is also a fellow of CU Boulder's Institute of Arctic and Alpine Research (INSTAAR). "Being able to predict these patterns of weathering puts us in a position to understand things we care about, from water supplies to maintaining healthy soils.""Soil resources are precious," said Robert Anderson, also an INSTAAR fellow. "One of the aspects of the landscape that we had to embrace in this modeling effort is that it takes thousands of years to generate the soil we have. If it is scraped away or misused, it's not going to be replaced in human timescales. Mismanagement means you will never get it back.""But to me," he said, "it is interesting enough, and satisfying enough, to explain why you can dig a pit 20 feet deep with a shovel in South Carolina, and have to resort to a pick axe within 2 feet in Colorado. It's all about the weather."
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November 13, 2018
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https://www.sciencedaily.com/releases/2018/11/181113110411.htm
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Warmer winter temperatures linked to increased crime
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Milder winter weather increased regional crime rates in the United States over the past several decades, according to new research that suggests crime is related to temperature's effect on daily activities.
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A new study published in The findings support the theory that three major ingredients come together to bring about crime: a motivated offender, a suitable target, and the absence of a guardian to prevent a violation of the law. During certain seasons, namely winter, milder weather conditions increase the likelihood these three elements come together, and that violent and property crimes will take place, according to the new study. Unexpectedly, warmer summer temperatures were not linked with higher crime rates.The new research abates existing theories that hot temperatures drive aggressive motivation and behavior, according to the study's authors. Instead, the new research suggests crime is related to the way climate alters people's daily activities."We were expecting to find a more consistent relationship between temperature and crime, but we weren't really expecting that relationship to be changing over the course of the year," said Ryan Harp, lead author of the study and a doctoral candidate in the Department of Atmospheric and Oceanic Sciences at the University of Colorado Boulder. "That ended up being a pretty big revelation for us."Understanding how climate affects crime rates could expand the boundaries of what scientists would consider to be a climate and health connection, Harp said."Ultimately, it's a health impact," he said. "The relationship between climate, human interaction, and crime that we've unveiled is something that will have an impact on people's wellbeing."Previous studies have found a link between temperature and the incidence of crime, but none have looked at the relationship on a regional level and only some have controlled for underlying seasonal changes, allowing researchers to identify the potential underlying mechanism.In the new study, Harp and his co-author conducted a systematic investigation into the relationship between large-scale climate variability and regionally-aggregated crime rates, using a technique that allowed them to group together detailed spatial data on seasonal temperature and crime rates from across the United States.They compared crime and climate data from the Federal Bureau of Investigation's Uniform Crime Reporting (UCR) Program and the National Oceanic and Atmospheric Administration's North American Regional Reanalysis (NARR). The data encompassed 16,000 cities across five defined US regions -- Northeast, Southeast, South Central, West, and Midwest -- from 1979 to 2016.Their finding that violent crime is almost always more prevalent when temperatures are warmer in the winter months was especially notable in areas with the strongest winters, like the Midwest and Northeast, according to the researchers.The new findings showing that increasing temperatures matter more in the winter than in the summer is interesting, said Marshall Burke, assistant professor of Earth System Science at Stanford University, who was not involved with the new study."The authors rightly suggest that this is more consistent with warmer temperatures altering people's patterns of activity, like going outside more, than a physiological story about temperature and aggression," he said.
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November 13, 2018
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https://www.sciencedaily.com/releases/2018/11/181113110335.htm
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Arctic sea ice: Simulation versus observation
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As an indicator of the impacts of climate change, Arctic sea ice is hard to beat. Scientists have observed the frozen polar ocean advance and retreat at this most sensitive region of the Earth over decades for insight on the potential ripple effects on assorted natural systems: global ocean circulation, surrounding habitats and ecosystems, food sources, sea levels and more.
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Despite efforts to make model simulations more closely mirror actual observations of Arctic sea ice melt, however, a gap has opened: Reports on the ground indicate the ice is melting at a much faster rate than predicted by global climate models."Based on this phenomenon, people have different opinions," said UC Santa Barbara climate scientist Qinghua Ding, an assistant professor in the campus's Earth Research Institute. The consensus of the climate science community, he said, is leaning toward the idea that the discrepancy is due to flawed modeling. "It's something like the model has some bias; it has some low sensitivity to anthropogenic forcing," he explained.Ding and his group disagree. In a study titled "Fingerprints of internal drivers of Arctic sea ice loss in observations and model simulations," published in the journal "Actually, we're comparing apples to oranges," Ding said of the discrepancy between real-time observation and simulated Arctic ice melt driven by anthropogenic forcing. The average of models, he explained, accounts only for what effects are a result of historical radiative forcing -- calculations based mostly on levels of greenhouse gases -- but don't rely on, for instance, the short-term variations in sea surface temperatures, humidity, atmospheric pressure and other factors both local and connected to other phenomena elsewhere on Earth. Such higher-frequency events often show up as noise in the repeated, individual runs of the simulations as scientists look for general long-term trends."Any one run of a model will have random noise," said Bradley Markle, a postdoctoral scholar in Ding's research group. "If you take 20 or 30 runs of a model, they will each have their own random noise, but they will cancel each other out." The resulting value is the average of all the simulation runs without the random variability. But that random variability may also be impacting what is being observed out on the ice, in addition to the forced signal.Due to their nature, internal variabilities are also likely to result in periods in which Arctic ice melt will appear to slow or even reverse, but in the bigger picture, climate scientists still see the eventual complete melting of Arctic sea ice for part of the year."There are so many reasons we focus on Arctic sea ice, but one of the main things people really care about is the timing of the ice-free summer," said Ding, referring to a time when the northern pole will no longer be the frozen frontier it has been even in the summer."Right now, the prediction is that in about 20 years, we will see an ice-free summer," Ding said. More than just a climate issue, he continued, the ice-free summer is also a societal issue, given the effects on fisheries and other food sources as well as natural resources and habitats that benefit from a frozen polar ocean. One of the things this discrepancy between simulation and observation indicates, he said, is that predictions about when this ice-free summer occurs will have to be tempered with some acknowledgement of the effects of internal variabilities."There's a large uncertainty associated with this time window," Ding said. "As we consider internal variabilities, plus COFor Markle, this situation highlights the disconnect that often occurs when talking about long-term climate trends versus short-term observations. Over the course of our human timescales of hours to days, we experience atmospheric temperature changes over several degrees, so a mean global temperature rise of one or two degrees doesn't seem all that significant."Likewise, year-to-year temperature variability, such as that associated with these tropical internal variations, can be several degrees in annual average temperature in a specific area, so near the same magnitude as the centuries-long global warming signal," he said.An example of this relatively short-term climate variability is the well-known El Niño Southern Oscillation (ENSO), the constant tipping between the El Niño and counterpart La Niña weather systems that brings both drought and rain, scarcity and abundance to different parts of the world. More extreme ENSO-driven weather behavior is expected as the Earth's climate seeks equilibrium in the face of an average global temperature increase of even a couple degrees."Just for reference, 20,000 years ago there was an ice sheet covering most of Canada during the height of the last ice age -- that was a four- or five-degree annual average temperature change," Markle said, "but it's a huge difference."Ding's research group continues to investigate the mysterious and complex internal drivers that affect Arctic sea ice, particularly those that originate in the warm, wet tropics."We're mostly interested in the period from the early 2000s to the present day, where we see such strong melting," said graduate student Ian Baxter, who also works with Ding. It's known, he added, that the effects of changes in the Arctic are no longer confined to the region and in fact spread to the mid-latitudes -- often in the form of cold weather outbreaks. The group is interested in how effects in the tropics could spread beyond that region and affect the Arctic.
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November 12, 2018
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https://www.sciencedaily.com/releases/2018/11/181112082430.htm
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Kawasaki disease: One disease, multiple triggers
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Researchers at University of California San Diego School of Medicine, Scripps Institution of Oceanography, and international collaborators have evidence that Kawasaki Disease (KD) does not have a single cause. By studying weather patterns and geographical distributions of patients in San Diego, the research team determined that this inflammatory disease likely has multiple environmental triggers influenced by a combination of temperature, precipitation and wind patterns. Results will be published in the November 12 online edition of
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"We are seeing firsthand evidence of these weather patterns in San Diego, where eight children have recently been diagnosed with Kawasaki Disease. Recent low pressure systems in San Diego have been associated with two distinct clusters of the disease," said Jane C. Burns, MD, pediatrician at Rady Children's Hospital-San Diego and director of the Kawasaki Disease Research Center at UC San Diego School of Medicine. "Our research is pointing towards an association between the large-scale environment, what's going on with our climate on a large scale, and the occurrence of these clusters."Kawasaki disease is the most common acquired heart disease in children. Untreated, roughly one-quarter of children with KD develop coronary artery aneurysms -- balloon-like bulges of heart vessels -- that may ultimately result in heart attacks, congestive heart failure or sudden death.Burns and her team examined 1,164 cases of KD treated at Rady Children's Hospital over 15 years. Noticeable clusters of KD cases were often associated with distinct atmospheric patterns that are suspected to transport or concentrate agents that result in KD. Days preceding and during the KD clusters exhibited higher than average atmospheric pressure and warmer conditions in Southern California, along with a high pressure feature south of the Aleutian Islands."For the first time, we have evidence that there is more than one trigger for Kawasaki Disease. Up until now, scientists have been looking for one 'thing' that triggers KD," said Burns. "Now we see that there are distinct clusters of the disease with different patterns suggesting varying causes."Gene expression analysis further revealed distinct groups of KD patients based on their gene expression pattern, and that the different groups were associated with certain clinical characteristics."Our data suggest that one or more environmental triggers exist, and that episodic exposures are influenced at least in part by regional weather conditions. We propose that characterization of the environmental factors that trigger KD in genetically susceptible children should focus on aerosols inhaled by patients who share common disease characteristics," said Burns who has studied KD for more than 35 years.Although KD is estimated to affect fewer than 6,000 children in the U.S. each year, the incidence is rising in San Diego County. While the average incidence per 100,000 children less than 5 years of age residing in San Diego County was approximately 10 for the decade of the 1990s, the estimate from 2006 to 2015 was 25.5. This increase may be attributed to the efforts of the KD team at Rady Children's Hospital to teach local physicians how to diagnose KD. Or it may be due to increasing exposure to the environmental triggers of the disease.Prevalence rates of KD are increasing among children in Asia. Japan has the highest incidence rate, with more than 16,000 new cases per year. One in every 60 boys and one in every 75 girls in Japan will develop KD during childhood.Incidence rates in the U.S. are approximately 19 to 25 cases per 100,000 children under age 5 -- but are higher in children of Asian descent. Predictive models estimate that by 2030, 1 in every 1,600 American adults will have been affected by the disease.
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November 8, 2018
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https://www.sciencedaily.com/releases/2018/11/181108205321.htm
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UK wine-making areas to rival Champagne revealed
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Research from the University of East Anglia has identified areas of the UK which could rival the Champagne region of France.
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Climate and viticulture experts have identified nearly 35,000 hectares of prime viticultural land for new and expanding vineyards -- much of it in Kent, Sussex and East Anglia.Prof Steve Dorling, from UEA's School of Environmental Sciences, said: "English and Welsh vineyards are booming, and their wine is winning international acclaim."This summer's heatwave has led to a record grape harvest and a vintage year for English and Welsh wine, prompting great interest in investment and land opportunities."But despite a trend of warming grape-growing seasons, this season has been quite unusual in terms of weather. English and Welsh grape yields are generally quite low and variable by international standards, so we wanted to identify the best places to plant vineyards and improve the sector's resilience to the UK's often fickle weather."The research team, with help from wine producers, used new geographical analysis techniques to assess and grade every 50 x 50 m plot of land in England and Wales for suitability.Lead author Dr Alistair Nesbitt said: "Interestingly, some of the best areas that we found are where relatively few vineyards currently exist such as in Essex and Suffolk -- parts of the country that are drier, warmer and more stable year-to-year than some more established vineyard locations."The techniques we used enabled us to identify areas ripe for future vineyard investments, but they also showed that many existing vineyards are not that well located, so there is definitely room for improvement and we hope our model can help boost future productivity."Entering into viticulture and wine production in England and Wales isn't for the faint hearted -- the investment required is high and risks are significant."But as climate change drives warmer growing season temperatures in England and Wales, this new viticulture suitability model allows, for the first time, an objective and informed rapid assessment of land at local, regional and national scales."The research was funded by the Natural Environment Research Council (NERC).
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November 5, 2018
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https://www.sciencedaily.com/releases/2018/11/181105122452.htm
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How to reduce the impact of shipping vessel noise on fish? Slow them down
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The western Canadian Arctic's natural underwater soundscape has been shielded from the din of commercial shipping by the sea ice that covers the area, rendering it mostly inaccessible to shipping vessels. But with large amounts of ice shrinking in the Arctic Ocean, a growing number of ships are gaining access to the area. This trend is expected to accelerate.
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One concern with vessel transits is how noise pollution can detrimentally affect marine animals -- including Arctic cod -- given the critical importance of these fish in the Arctic food web."Noise from shipping traffic can lead to acoustic masking, reducing the ability of cod and other marine animals to detect and use sound for communication, foraging, avoiding predators, reproduction, and navigation," said Matt Pine, a research fellow at the University of Victoria and Wildlife Conservation Society Canada (WCS Canada).Pine and his colleagues at the University of Victoria, WCS Canada and JASCO Applied Sciences have found that the negative impact of noise from shipping vessels can be mitigated by reducing the ship's speed. They will present their research at the Acoustical Society of America's 176th Meeting, held in conjunction with the Canadian Acoustical Association's 2018 Acoustics Week in Canada, Nov. 5-9 at the Victoria Conference Centre in Victoria, Canada.Pine's research team investigated potential relief in acoustic masking by reducing the speed of container and cruise ships by 10 knots, from 25 knots (equivalent to about 17 mph) to 15 knots (equivalent to about 11.5 mph).The research has involved advanced propagation modeling of ship noise and the acoustic masking effects on arctic cod, two types of whales (belugas and bowheads) and two types of seals (bearded and ringed).The researchers incorporated field data to produce computer simulations in which container and cruise ships passed through the western Canadian Arctic via the Northwest Passage.They explored the effect each type of ship had on the volume of the ocean surrounding a fish, seal and whale within which prey, a predator or other danger could be heard by that animal."Our modeling study shows that reduction in acoustic masking effects can be substantial," Pine said. However, he cautioned, the findings are not so clear-cut."Acoustic masking effects are quite dynamic, and slowing down a vessel doesn't necessarily equal the same benefits for all animals," he explained.For example, sometimes smaller masking effects were seen in certain weather conditions. For the fish, however, weather conditions did not make a difference in the masking effects because their hearing thresholds in most frequency bands are above the ambient levels."In this case, the type of vessel was more important," Pine said, "with cruise ships reducing their masking effect more if slowed by 10 knots than the container vessels nearer the vessel."
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October 30, 2018
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https://www.sciencedaily.com/releases/2018/10/181030150702.htm
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Commercial shellfish landings decline likely linked to environmental factors
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Researchers studying the sharp decline between 1980 and 2010 in documented landings of the four most commercially-important bivalve mollusks -- eastern oysters, northern quahogs, softshell clams and northern bay scallops -- have identified the causes.
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Warming ocean temperatures associated with a positive shift in the North Atlantic Oscillation (NAO), which led to habitat degradation including increased predation, are the key reasons for the decline of these four species in estuaries and bays from Maine to North Carolina.The NAO is an irregular fluctuation of atmospheric pressure over the North Atlantic Ocean that impacts both weather and climate, especially in the winter and early spring in eastern North America and Europe. Shifts in the NAO affect the timing of species' reproduction, growth and availability of phytoplankton for food, and predator-prey relationships, all of which contribute to species abundance. The findings appear in "In the past, declines in bivalve mollusks have often been attributed to overfishing," said Clyde Mackenzie, a shellfish researcher at NOAA Fisheries' James J. Howard Marine Sciences Laboratory in Sandy Hook, NJ and lead author of the study. "We tried to understand the true causes of the decline, and after a lot of research and interviews with shellfishermen, shellfish constables, and others, we suggest that habitat degradation from a variety of environmental factors, not overfishing, is the primary reason."Mackenzie and co-author Mitchell Tarnowski, a shellfish biologist with the Maryland Department of Natural Resources, provide details on the declines of these four species. They also note the related decline by an average of 89 percent in the numbers of shellfishermen who harvested the mollusks. The landings declines between 1980 and 2010 are in contrast to much higher and consistent shellfish landings between 1950 and 1980.Exceptions to these declines have been a sharp increase in the landings of northern quahogs in Connecticut and American lobsters in Maine. Landings of American lobsters from southern Massachusetts to New Jersey, however, have fallen sharply as water temperatures in those areas have risen."A major change to the bivalve habitats occurred when the North Atlantic Oscillation (NAO) index switched from negative during about 1950 to 1980, when winter temperatures were relatively cool, to positive, resulting in warmer winter temperatures from about 1982 until about 2003," Mackenzie said. "We suggest that this climate shift affected the bivalves and their associated biota enough to cause the declines."Research from extensive habitat studies in Narragansett Bay, RI and in the Netherlands, where environments including salinities are very similar to the northeastern U.S, show that body weights of the bivalves, their nutrition, timing of spawning, and mortalities from predation were sufficient to force the decline. Other factors likely affecting the decline were poor water quality, loss of eelgrass in some locations for larvae to attach to and grow, and not enough food available for adult shellfish and their larvae."In the northeast U.S., annual recruitments of juvenile bivalves can vary by two or three orders of magnitude," said Mackenzie, who has been studying bay scallop beds on Martha's Vineyard with local shellfish constables and fishermen monthly during warm seasons for several years. In late spring-early summer of 2018, a cool spell combined with extremely cloudy weather may have interrupted scallop spawning, leading to what looks like poor recruitment this year. Last year, Nantucket and Martha's Vineyard had very good harvests due to large recruitments in 2016."The rates of survival and growth to eventual market size for shellfish vary as much as the weather and climate," Mackenzie said.Weak consumer demand for shellfish, particularly oysters, in the 1980s and early 1990s has shifted to fairly strong demand as strict guidelines were put in place by the Interstate Shellfish Sanitation Conference in the late 1990s regarding safe shellfish handling, processing and testing for bacteria and other pathogens. Enforcement by state health officials has been strict. The development of oyster aquaculture and increased marketing of branded oysters in raw bars and restaurants has led to a large rise in oyster consumption in recent years.Since the late 2000s, the NAO index has generally been fairly neutral, neither very positive nor negative. As a consequence, landings of all four shellfish species have been increasing in some locations. Poor weather for bay scallop recruitment in both 2017 and 2018, however, will likely mean a downturn in landings during the next two seasons.
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October 29, 2018
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https://www.sciencedaily.com/releases/2018/10/181029084057.htm
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Bigger = better: Big bees fly better in hotter temps than smaller ones do
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Arizona State University researchers have found that larger tropical stingless bee species fly better in hot conditions than smaller bees do. Larger size may help certain bee species better tolerate high body temperatures. The findings run contrary to the well-established temperature-size "rule," which suggests that ectotherms -- insects that rely on the external environment to control their temperature -- are larger in cold climates and smaller in hot ones. The research will be presented today at the American Physiological Society's (APS) Comparative Physiology: Complexity and Integration conference in New Orleans.
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Insects fall into three categories:"Bees fall along this entire range," explained lead author Meghan Duell, a graduate student at Arizona State University. "Most [insects] employ some means of behavioral thermoregulation. As body size increases, it's more likely that insects will be able to behaviorally and physiologically thermoregulate, especially in flying insects. Bigger bees, like bumblebees or the larger species in the work I'm presenting, are partially endothermic. They can warm themselves by shivering their flight muscles to produce heat but do not constantly physiologically regulate body temperature."Excessive heat, such as that in the rainforests of Panama where the bees in this study originated from, can limit a bee's ability to fly. "If bees stop flying as often in hot temperatures, the amount of time they have to forage (and therefore pollinate flowering plants) decreases. This can mean they aren't able to collect enough food to maintain the colony," Duell said. "On a large enough scale, this negatively impacts the overall bee population and the plants they pollinate while collecting pollen and nectar for food."Therefore, better flying performance is an advantage for bees in hot climates. Bees that are unable to fly in hot conditions ultimately end up walking from flower to flower, which is far less efficient than flying and means they are subject to even hotter temperatures on the surfaces of flowers and leaves.In the new study, Duell and her collaborator, Jon F. Harrison, PhD, measured air and thorax temperatures of 10 species of stingless bees -- which varied in body mass between 2 and 120 milligrams -- to assess how well bees fly at high temperatures and the variations seen based on body size. The researchers also measured leaf and flower surface temperatures and air temperatures in sun and shade within the bees' native tropical forest canopy.With the temperature-size rule in mind, the researchers were expecting the smaller bees to perform better in hot weather. Surprisingly, the opposite was true. Their findings showed that large bees seem to have adapted to the high temperatures and by using their ability to maintain their own heat. This flight performance advantage was also seen in cooler altitudes of the hot Panamanian rain forest."Essentially the bigger bees are exposed to higher temperatures -- sometimes in excess of 10 degrees Celsius hotter than air temperature -- because they produce a lot of heat while flying. That same heat producing ability gives them an advantage in cooler regions as well because they can be active earlier in the morning, later into the evening or on cooler days compared to smaller bees," Duell said.
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October 24, 2018
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https://www.sciencedaily.com/releases/2018/10/181024150145.htm
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Annual dead-zone report card for the Chesapeake Bay, U.S.
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An annual model-based report on "dead-zone" conditions in the Chesapeake Bay during 2018 indicates that the total volume of low-oxygen, "hypoxic" waters was very similar to the previous year, but a sharp drop in hypoxia during late July shows the critical role of wind mixing in short-term variations in the oxygen content of Bay waters. The duration of hypoxia in 2018 was greater than in recent years.
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Dead zones are one of the major water-quality concerns facing the Bay and coastal waters worldwide. They form when rivers carry in excess nitrogen from fertilizers, wastewater, and other sources, fueling short-lived blooms of algae. Bacteria then eat the dead, sinking algae, consuming from bottom waters the dissolved oxygen that fish, shellfish, crabs, and other animals need to survive. Bay dead zones peak during summer, when hot weather encourages algal growth and drives gases from the water, while calm winds typically preclude the mixing of relatively oxygen-rich surface waters into the depths.The Annual Chesapeake Bay Hypoxia Report Card is the brainchild of Dr. Marjy Friedrichs of the Virginia Institute of Marine Science and Dr. Aaron Bever of Anchor QEA, an environmental and engineering consulting firm. Bever earned his Ph.D. from William & Mary's School of Marine Science at VIMS in 2010.The team's report card summarizes oxygen conditions in the Bay each year as estimated by their 3-D, real-time hypoxia forecast model, originally developed with funding from NOAA. The model is based on 30 years of water quality data collected by the Chesapeake Bay Program, and is forced daily by wind data provided by NOAA and river-input data provided by the U.S. Geological Survey. The modeling team, which includes Dr. Raleigh Hood of the University of Maryland Center for Environmental Science, also generates dissolved oxygen statistics for previous years for comparative purposes.Because springtime inflows from the Susquehanna River -- Chesapeake Bay's largest tributary -- were high in 2018, scientists predicted that summer 2018 would have an above average amount of hypoxia, a forecast that held true through mid-July, when unusually strong winds reduced the Bay's hypoxic volume to near zero. Hypoxia increased rapidly again in early August and peaked at a higher value in early September than in previous years. Strong winds in September again mixed Bay waters, resulting in a large reduction in hypoxic volume.Says Bever, "The lack of hypoxia in late July was very atypical of historical dissolved oxygen conditions for mid-summer." Friedrichs adds, "It's fascinating how the hypoxic volume was so low in late July and so high in early September, but overall the hypoxic volume was basically the same as last year.""Overall," she says, "our model indicates that the total amount of hypoxia in 2018 was similar to 2017, but that the seasonal patterns in hypoxia were very different. In addition to late-July's major hypoxic dip, low-oxygen conditions started earlier and lasted longer in 2018 than in recent years." Friedrichs notes that related research suggests that an earlier onset of spring hypoxia may be growing more common, as May temperatures increase due to climate change.To put this year's late-July "hypoxia hiatus" in perspective, Friedrichs notes that low-oxygen waters occupy on average about 7% of the Bay's entire volume during summer, and about 20% of the volume of Maryland's Chesapeake waters -- where Bay hypoxia is most pronounced. This year, hypoxia occupied 14.4% of the Bay's mainstem waters on July 5 (a volume of 9.9 cubic kilometers), but by July 26 -- just three weeks later -- had fallen to 0.14% of mainstem water, with a volume of only 0.1 km3.The findings of the VIMS hypoxia model and report card generally match the monitoring-based report provided by the Maryland Department of Natural Resources for the Maryland portion of the Bay. Variations in results are partially due to different reporting periods, as the Virginia report includes results from the onset of hypoxia in spring to its cessation in the autumn, while Maryland's DNR reports on Maryland conditions from June through September, the period that specifically relates to the EPA's water-quality-criteria assessment for summer dissolved oxygen.
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October 22, 2018
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https://www.sciencedaily.com/releases/2018/10/181022085820.htm
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Rising temperatures and human activity are increasing storm runoff and flash floods
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Hurricanes Florence and Michael in the U.S. and Super Typhoon Mangkhut in the Philippines have shown the widespread and harmful impact of weather extremes on both ecosystems and built communities, with flash floods causing more deaths, as well as property and agriculture losses than from any other severe weather-related hazards. These losses have been increasing over the past 50 years and have exceeded $30 billion per year in the past decade. Globally, almost one billion people now live in floodplains, raising their exposure to river flooding from extreme weather events and underscoring the urgency in understanding and predicting these events.
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Columbia Engineering researchers have demonstrated for the first time that runoff extremes have been dramatically increasing in response to climate and human-induced changes. Their findings, published today in The researchers discovered that changes in storm runoff extremes in most regions of the world are in line with or higher than those of precipitation extremes. They noted that different responses of precipitation and storm runoff to temperature can be attributed not only to warming, but also to factors like land-use and land-cover changes, water and land management, and vegetation changes that have altered the underlying surface conditions and hydrological feedbacks that have, in turn, increased storm runoff."Our work helps explain the underlying physical mechanisms related to the intensification of precipitation and runoff extremes," Gentine said. "This will help improve flood forecasting and early-warning alerts. Our findings can help provide scientific guidance for infrastructure and ecosystem resilience planning, and could help formulate strategies for tackling climate change."Precipitation is generated after water vapour condenses in the atmosphere, and precipitation intensity is governed by the availability of atmospheric water vapour. Because the atmosphere can hold more moisture as temperature rises, climate scientists expect to see an intensification of precipitation extremes with climate change.Because previous studies mainly investigated the precipitation response, Gentine's team decided to examine the response of both precipitation and storm runoff extremes to naturally and anthropogenically driven changes in surface temperature and atmospheric moisture content. They performed a global scale hydrological analysis to characterize the responses and their underlying physical mechanisms. The researchers then assessed the influence of variability across decades on the scaling of runoff extremes and temperature, then systematically compared this with changes in precipitation extremes. Their observational daily runoff data came from the Global Runoff Data Centre (GRDC) datasets, and daily precipitation and near-surface air temperature data from Global Summary of the Day (GSOD) dataset."We were trying to find the physical mechanisms behind why precipitation and runoff extremes are increasing all over the globe," said the study's lead author Jiabo Yin, a visiting student from Wuhan University working in Gentine's group. "We know that precipitation and runoff extremes will significantly intensify in the future, and we need to modify our infrastructures accordingly. Our study establishes a framework for investigating the runoff response."Precipitation is governed both by thermodynamics (the relationship of water vapour to temperature) and atmospheric dynamics. Gentine's team plans next to try to partition the impacts of thermodynamic and dynamics on precipitation to gain a deeper understanding about precipitation intensification. They will also focus on detecting changes due to warming versus those due to human activity in order to establish an adaptive water resources management system.
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October 18, 2018
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https://www.sciencedaily.com/releases/2018/10/181018095435.htm
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Climate stress will make cities more vulnerable
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Built upon on a complex system of canals, water catchments and embankments, Angkor was once the largest city in the world, covering an area of approximately 1000km
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The multidisciplinary team of academics, researchers and students led by Professor Mikhail Prokopenko, Director of the Complex Systems Research Group, and Associate Professor Daniel Penny, Director of the Greater Angkor Project, found that the medieval city suffered external climate stress coupled with overloaded infrastructure within the canal system, which through in-depth mapping showed evidence of a vulnerability to catastrophic failures.Professor Prokopenko believes that the study is crucial to improving infrastructure in an era of increasing frequent extreme weather events which are creating new and pressing risks to urban environments.He said, "Complex infrastructural networks provide critical services to cities but can be vulnerable to external stressors, including climatic variability."The cascading failure of critical infrastructure in Angkor which resulted from climate extremes re-emphasises the importance of building resilience into modern networks."Having worked on the Greater Angkor Project for 18 years, Professor Daniel Penny said, "For the first time, identifying a systemic vulnerability in Angkor's infrastructural network has provided a mechanistic explanation for its demise, which comes with an important lesson for our contemporary urban environments."Both of the researchers believe that the risks of network collapse have become more acute as urban conglomerations become larger, more complex, and have more people living in them."The water management infrastructure of Angkor has been developed over centuries, becoming very large, tightly interconnected, and dependent on older and ageing components. The change in the middle of the 14th Century C.E., from prolonged drought to particularly wet years, put too much stress on this complex network, making the water distribution unstable," said Professor Prokopenko.The factors behind Angkor's demise are also comparable to the challenges faced by modern urban communities that are struggling with complex critical infrastructure and extreme weather events, such as floods and drought.Professor Prokopenko continued, "We found that infrastructural networks in preindustrial urban environments in fact share very common topological and functional characteristics with modern complex networks."In complex systems, catastrophic responses and cascading failures, such as an abandonment of a city, can also be caused by very small changes or even a series of accumulated changes which cause a system or network to reach a 'tipping point'.There are several examples of tipping points faced by the modern world, such as the Amazon die-back, the 2016 South Australian power outage and the El Niño-Southern Oscillation.Professor Prokopenko believes the team's research emphasises the need for governments and communities to focus on building resilience into modern urban networks, particularly in the face of a changing climate."Not only is it possible that catastrophic, infrastructural failure may also have occurred in the past, but the results from this research are critical to our community's understanding of how climate and distributed resources affect the functioning of our cities and societies."If we don't build resilience into our critical infrastructure, we may face severe and lasting disruptions to our civil systems, that can be intensified by external shocks and threaten our environment and economy," he concluded.The research was conducted as part of the Greater Angkor Project in conjunction with the University of Sydney's CRISIS initiative which models social risks and extreme events.The Greater Angkor Project is a collaborative research program between the University of Sydney (Archaeology and Geosciences), the APSARA National Authority and the École Française d'Extrême-Orient, that has attempted to explain the demise and abandonment of Angkor for the past 16 years.The new study was published in the
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October 17, 2018
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https://www.sciencedaily.com/releases/2018/10/181017111033.htm
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Bursting the clouds for better communication
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We live in an age of long-range information, transmitted either by underground optical fibre or by radio frequency from satellites. But the throughput today is so great that radio frequency is no longer enough in itself. Research is turning towards the use of lasers which, although technically complex, have several advantages, especially when it comes to security. However, this new technology -- currently in the testing phase -- faces a major problem: clouds. Due to their density, clouds stop the laser beams and scramble the transfer of information. Researchers at the University of Geneva (UNIGE), Switzerland, have devised an ultra-hot laser that creates a temporary hole in the cloud, which lets the laser beam containing the information pass through. It is a world first that you can read all about in the journal
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Although satellite radio communication is powerful, it can no longer keep up with the daily demand for the flow of information. Its long wavelengths limit the amount of information transmitted, while the frequency bands available are scarce and increasingly expensive. Furthermore, the ease with which radio frequencies can be captured poses ever more acute security problems... which is why research is turning to lasers. "It's a new technology that is full of promise," says Jean-Pierre Wolf, professor in the Physics Section at UNIGE's Faculty of Science. "The very short wavelengths can carry 10,000 times more items of information than radio frequency, and there aren't any limits to the number of channels. Lasers can also be used to target a single person, meaning it's a highly secure form of communication."But there is a problem: the laser beams cannot penetrate clouds and fog. So, if the weather is bad, it is impossible to transmit information using lasers.To counter this difficulty, current research is building more and more ground stations capable of receiving the laser signals in various parts of the world. The idea is to choose the station targeted by the satellite according to the weather. Although this solution is already operational, it is still dependent on weather conditions. It also creates certain problems regarding the settings on the satellite, which have to be processed upstream of the communication, without any assurance that there will not be any cloud cover at the appointed time."We want to get around the problem by making a hole directly through the clouds so that the laser beam can pass through," explains Professor Wolf. His team has developed a laser that heats the air over 1,500 degrees Celsius and produces a shock wave to expel sideways the suspended water droplets that make up the cloud. This creates a hole a few centimetres wide over the entire thickness of the cloud. It is the discovery of these ultra-powerful lasers that has just been awarded the Nobel Prize for Physics 2018. "All you then need to do is keep the laser beam on the cloud and send the laser that contains the information at the same time," says Guillaume Schimmel, a researcher in the team led by Wolf. "It then slips into the hole through the cloud and allows the data to be transferred."This "laser cleaner" is currently being tested on artificial clouds that are 50 cm thick but that contain 10,000 times more water per cm3 than a natural cloud -- and it works, even if the cloud is moving. "Our experiments mean we can test an opacity that is similar to natural clouds. Now it's going to be about doing it on thicker clouds up to one kilometre thick," continues Wolf. "It's also about testing different types of clouds in terms of their density and altitude," adds Schimmel.This new technology represents an important step towards the commercial use of satellite laser communication. "We're talking about possible global implementation by 2025, and our idea is to be ready and to allow countries that are overcast to have this technology!" concludes Professor Wolf.
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October 17, 2018
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https://www.sciencedaily.com/releases/2018/10/181017094937.htm
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School students identify sounds caused by solar storm
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School students have successfully identified sounds caused by a solar storm in Earth's magnetic shield, as part of a Queen Mary University of London research project.
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The findings, by a group of year 12 pupils from Eltham Hill School in south east London, have now been published in the scientific journal The project encouraged schools in London to take part in university research and the resulting study presents a novel approach to undertaking scientific research by making data audible for school students to explore by listening to it.Earth's magnetic shield, which protects us against harmful radiation from the Sun and more distant sources, is rife with a symphony of ultra-low frequency sounds. These sounds, or waves, are too low-pitch for us to hear but a researcher at Queen Mary made satellite recordings of them audible by dramatically speeding up their playback.The group of students identified a series of waves whose pitch decreased over the course of several days. They found that this event occurred after a Coronal Mass Ejection or 'solar storm' caused a great disturbance to Earth's space environment.The study shows that the waves were somewhat like the vibrations of a plucked guitar string which forms a distinct note, but applied to Earth's magnetic field, while the changing pitch was due to the recovery process of our space environment following the storm.Events like these have rarely been discussed, but by taking advantage of the audible data's sped up playback and the amazing abilities of the human ear, the study reveals many similar patterns present in the data showing them to be far more common than previously thought.Dr Martin Archer, space physicist at Queen Mary's School of Physics and Astronomy, and academic lead on the project, said: "The findings could transform the field, enabling more members of the public to contribute to research just by listening to data and finding things that scientists might have missed. We hope that this becomes more widespread since we are living in the age of 'big data'."Isobel Currie, one of the students from Eltham Hill School involved in the project, added: "It was truly amazing to hear how significant the event we found was and that it will be forming the basis of a proper scientific paper. We gained so much experience and developed many skills during our research that will be useful during our time at university, and it gave us a great insight into the work conducted at that level."Disturbances to Earth's magnetic shield like this pose risks to our everyday lives because they can damage technology like power grids, GPS and even passenger airlines. These waves are one way the energy that comes from solar storms can be transferred around Earth's space environment.The study has highlighted that current methods have been missing some important and fairly common classes of waves and that new techniques may be able to help.Dr Archer said: "Making data audible is uncommon and when done so is typically used only by the researchers themselves. Involving the public in undertaking research, known as citizen science, tends to focus on crowdsourcing data or analysis unlike this more explorative method. However, the study shows that useful and unexpected scientific results can come from this combined approach."The data was taken from the USA's Geostationary Operational Environment Satellites which are operated by the National Oceanic and Atmospheric Administration. Following the potential demonstrated in the paper, they will be making the full audible dataset publicly available.The researchers will now be looking to find out which disturbances of Earth's magnetic shield lead to these decreasing pitch sounds and why. This will build up a better picture of what happens and may improve the forecasting of space weather.
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October 16, 2018
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https://www.sciencedaily.com/releases/2018/10/181016150654.htm
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Antarctic ice shelf 'sings' as winds whip across its surface
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Winds blowing across snow dunes on Antarctica's Ross Ice Shelf cause the massive ice slab's surface to vibrate, producing a near-constant set of seismic "tones" scientists could potentially use to monitor changes in the ice shelf from afar, according to new research.
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The Ross Ice Shelf is Antarctica's largest ice shelf, a Texas-sized plate of glacial ice fed from the icy continent's interior that floats atop the Southern Ocean. The ice shelf buttresses adjacent ice sheets on Antarctica's mainland, impeding ice flow from land into water, like a cork in a bottle.When ice shelves collapse, ice can flow faster from land into the sea, which can raise sea levels. Ice shelves all over Antarctica have been thinning, and in some cases breaking up or retreating, due to rising ocean and air temperatures. Prior observations have shown that Antarctic ice shelves can collapse suddenly and without obvious warning signs, which happened when the Larsen B ice shelf on the Antarctic Peninsula abruptly collapsed in 2002.To better understand the physical properties of the Ross Ice Shelf, researchers buried 34 extremely sensitive seismic sensors under its snowy surface. The sensors allowed the researchers to monitor the ice shelf's vibrations and study its structure and movements for over two years, from late 2014 to early 2017.Ice shelves are covered in thick blankets of snow, often several meters deep, that are topped with massive snow dunes, like sand dunes in a desert. This snow layer acts like a fur coat for the underlying ice, insulating the ice below from heating and even melting when temperatures rise.When the researchers started analyzing seismic data on the Ross Ice Shelf, they noticed something odd: Its fur coat was almost constantly vibrating.When they looked closer at the data, they discovered winds whipping across the massive snow dunes caused the ice sheet's snow covering to rumble, like the pounding of a colossal drum (see: They also noticed the pitch of this seismic hum changed when weather conditions altered the snow layer's surface. They found the ice vibrated at different frequencies when strong storms rearranged the snow dunes or when the air temperatures at the surface went up or down, which changed how fast seismic waves traveled through the snow."It's kind of like you're blowing a flute, constantly, on the ice shelf," said Julien Chaput, a geophysicist and mathematician at Colorado State University in Fort Collins and lead author of the new study published today in Just like musicians can change the pitch of a note on a flute by altering which holes air flows through or how fast it flows, weather conditions on the ice shelf can change the frequency of its vibration by altering its dune-like topography, according to Chaput."Either you change the velocity of the snow by heating or cooling it, or you change where you blow on the flute, by adding or destroying dunes," he said. "And that's essentially the two forcing effects we can observe."The hum is too low in frequency to be audible to human ears, but the new findings suggest scientists could use seismic stations to continuously monitor the conditions on ice shelves in near real-time. Studying the vibrations of an ice shelf's insulating snow jacket could give scientists a sense of how it is responding to changing climate conditions, according to Douglas MacAyeal, a glaciologist at the University of Chicago who was not connected to the new study but wrote a commentary about the findings also published today in Changes to the ice shelf's seismic hum could indicate whether melt ponds or cracks in the ice are forming that might indicate whether the ice shelf is susceptible to breaking up."The response of the ice shelf tells us that we can track extremely sensitive details about it," Chaput said. "Basically, what we have on our hands is a tool to monitor the environment, really. And its impact on the ice shelf."
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October 15, 2018
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https://www.sciencedaily.com/releases/2018/10/181015084633.htm
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Predicting an El Niño or La Niña year 17 months in advance
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Changes in Atlantic Ocean sea surface temperatures can be used to predict extreme climatic variations known as El Niño and La Niña more than a year in advance, according to research conducted at Korea's Pohang University of Science and Technology and published in the journal
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The El Niño Southern Oscillation (ENSO) is an irregular, periodic variation in trade winds and sea and air temperatures in the equatorial region of the Pacific Ocean, . Its warming phase of sea surface temperatures, called El Niño, and cooling phase, called La Niña, affects weather and climate around the world. For example, El Niño conditions typically generate more typhoons in the Pacific Ocean and fewer hurricanes in the Atlantic Ocean, while La Niña conditions usually reverse the trend.Extensive studies have been conducted to better understand what triggers a distinct oscillation in order to predict associated climatic events. But accurate predictions are still limited to about a year or less before an ENSO swing. For example, studies have found that a peak in warm water in the equatorial Pacific precedes El Niño by about eight months. Also, an abnormal drop in sea surface temperatures in the tropical North Atlantic in early spring precedes El Niño conditions in the Pacific within about nine months.Now, researchers at Pohang University of Science and Technology and colleagues in Hawaii and Japan have found that an abnormal rise in sea surface temperatures in a large body of warm water, called the Atlantic Warm Pool -- comprising the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic -- triggers La Niña about 17 months later.The team analysed observational (1985-2016) and model simulation (1970-2000) data and found an unusual rise of sea surface temperature in the Atlantic Warm Pool in mid-summer to early fall leads to the formation of a northerly wind over the North Pacific. This generates cold sea surface temperatures, high sea level pressure, and a low-level high-pressure area called an anti-cyclone in the subtropical north-eastern Pacific that persist through the subsequent winter and spring. The cold sea surface temperature extends toward the equator. Together, these events lead to a coupling between sea surface temperature and surface winds in the equatorial Pacific in the spring, triggering La Niña. Falling sea surface temperatures in the Atlantic Warm Pool ultimately trigger El Niño. Both ENSO events are triggered 17 months after the initial changes in Atlantic Warm Pool sea surface temperatures.The robust relationship between these events can provide a longer lead time for ENSO predictions compared to those reported in previous studies, the researchers say. This relationship has only become strong enough for the purpose of these predictions in the past three decades. Before this, it was not statistically significant. Average rising sea surface temperatures in the Atlantic Warm Pool above 28°C seem to be responsible for this, the researchers say.They conclude that a model simulation that is able to capture the pattern that occurs between the Atlantic Warm Pool and the El Niño Southern Oscillation in the Pacific could extend the ability of climatologists to predict these swings, and their associated extreme weather and climate impacts, more than a year in advance.
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October 9, 2018
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https://www.sciencedaily.com/releases/2018/10/181009135958.htm
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'Sentinels of the sea' at risk from changing climate
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Climate change's effect on coastal ecosystems is very likely to increase mortality risks of adult oyster populations in the next 20 years.
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That is the finding of a new study led by the University of Nantes, the LEMAR (the Marine Environmental Science Laboratory) in Plouzané and the Cerfacs (European center for research and advanced training in scientific computing) in Toulouse (France).Published today in the journal The team's results show oyster mortality usually increases after warm and wet winters over Northern Europe, affected by recurrent storms embedded in large weather circulation patterns covering the whole North Atlantic basin -- known as the positive phase of the North Atlantic Oscillation (NAO).The study's lead author is Dr Yoann Thomas, from the French National Research Institute for Sustainable Development (IRD) at LEMAR. He said: "Benthic species like oysters are keystone species in coastal ecosystems. For example, they build reef habitats, which sustain a high biodiversity, and provide tremendous food source worldwide though fishing or aquaculture activities."But they are very sensitive to changes in climate and water quality, because they cannot move if a location becomes inhospitable. In this sense, oyster populations are sentinels of long-term climate fluctuations and climate trends, and more broadly of the 'health' of coastal ecosystems."We know the NAO is one of the key drivers of ecological variations like species individual growth rate, geographical distribution, phenology and survival. We show that recurrent positive NAO episodes in winter, leading to milder temperatures along the northern European coast, have a long-lasting effect on the biological and environmental factors influencing oyster mortality."We also show that the cumulative mortality rate over a year significantly increases after winters dominated by positive NAO. From a practical perspective, this lagged relationship can be used for potential predictability of annual mortality at several months lead-time."The researchers linked this climate-related risk to several environmental factors like the unlocking of the winter cold-water barrier for pathogens, the shortening of the resting phase for oyster, and enhanced metabolic rates leading to higher vulnerability in spring and summer.The storms also caused more fresh water to flow from rivers into the sea, which impacts oysters by lowering the salinity of the water.By analysing the results of more than 30 climate models and several greenhouse gases emission scenarios, the team used the extreme winter temperatures of the present-day NAO+ climate conditions as an analog to produce forecast assessments of oyster mortality risk factor in the next decades.Dr Thomas said: "What today are exceptional levels of mortality could become the norm by 2035, even if the global temperature increase is limited to ~2°C above the pre-industrial period as per the Paris agreement. Natural long-term climate variability on top of anthropogenic-induced warming could ever accelerate or delay the increasing risk by only a decade or so.He concluded: "The near-future looks bleak, but we show that this will be even worse without a clear reduction of the greenhouse gases emissions by human activities. We obviously need to take rapid action now to avoid further damage to very sensitive and vulnerable coastal ecosystems."
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October 4, 2018
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https://www.sciencedaily.com/releases/2018/10/181004095948.htm
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Scientists develop a new way to remotely measure Earth's magnetic field
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Researchers in Canada, the United States and Europe have developed a new way to remotely measure Earth's magnetic field -- by zapping a layer of sodium atoms floating 100 kilometres above the planet with lasers on the ground.
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The technique, documented this week in "The magnetic field at this altitude in the atmosphere is strongly affected by physical processes such as solar storms and electric currents in the ionosphere," says Paul Hickson an astrophysicist at the University of British Columbia (UBC) and author on the paper."Our technique not only measures magnetic field strength at an altitude that has traditionally been hidden, it has the side benefit of providing new information on space weather and atomic processes occurring in the region."Sodium atoms are continually deposited in the mesosphere by meteors that vaporize as they enter Earth's atmosphere. Researchers at the European Southern Observatory (ESO), the University of Mainz and UBC used a ground-based laser to excite the layer of sodium atoms and monitor the light they emit in response."The excited sodium atoms wobble like spinning tops in the presence of a magnetic field," explains Hickson. "We sense this as a periodic fluctuation in the light we're monitoring, and can use that to determine the magnetic field strength."Hickson and UBC PhD student Joschua Hellemeier developed the photon counting instrument used to measure the light coming back from the excited sodium atoms, and participated in observations conducted at astronomical observatories in La Palma.The ESO team, led by Bonaccini Calia, pioneered world-leading laser technology for astronomical adaptive optics used in the experiment. Project lead Felipe Pedreros and Dmitry Budker (Johannes Gutenberg University), Simon Rochester and Ronald Holzloehner (ESO), experts in laser-atom interactions, have led the theoretical interpretation and modeling for the study.
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October 4, 2018
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https://www.sciencedaily.com/releases/2018/10/181004085343.htm
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More wet and dry weather extremes projected with global warming
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Global warming is projected to spawn more extreme wet and dry weather around the world, according to a Rutgers-led study.
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Those extremes include more frequent dry spells in the northwestern, central and southern United States and in Mexico, and more frequent heavy rainfall events in south Asia, the Indochinese Peninsula and southern China.One reason -- subtropical stationary waves in northern summers, according to the study in the The intensity of subtropical stationary waves during northern summers increased from 1979 to 2013, and projections suggest the increase will accelerate as climate warms, the study says."Increasingly strong subtropical stationary waves play an important role in explaining the increase in extremely dry weather in North America and extremely wet weather in south and southeast Asia," said study lead author Jiacan Yuan, a post-doctoral associate in the Department of Earth and Planetary Sciences at Rutgers University-New Brunswick and the Rutgers Institute of Earth, Ocean, and Atmospheric Sciences.Subtropical stationary waves may serve as an important link connecting regional droughts and extreme rainfall events with global warming, the study says. Such extremes, which have increased significantly in recent decades because of a warming climate, can cause enormous economic losses and threaten lives.Examples of extreme events include catastrophic floods in South Asia during the 2017 monsoon season, when about 1,300 people died and more than 45 million people were affected, according to a United Nations Children's Fund report. A severe drought afflicted Texas in 2011, with direct agricultural losses estimated at $5.2 billion by the Texas AgriLife Extension Service.The study's coauthors include Robert Kopp, director of the Rutgers Institute of Earth, Ocean, and Atmospheric Sciences, as well as scientists at Duke University and Georgia Institute of Technology.
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October 3, 2018
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https://www.sciencedaily.com/releases/2018/10/181003134507.htm
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A warmer spring leads to less plant growth in summer
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Climate change influences plant growth, with springtime growth beginning earlier each year. Up to now, it was thought that this phenomenon was slowing climate change, as scientists believed this process led to more carbon being absorbed from the atmosphere for photosynthesis and more biomass production. However, as evaluations of satellite data undertaken at TU Wien have now shown, this is not the case. On the contrary, in many regions, an early spring actually leads to less plant growth.
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The climate models that have been used until now need to be modified and the world's climate is in an even more critical state than previously thought. The results have now been published in a large international study in the science journal "We already knew that climate change had shifted the timing of plant growth," says Matthias Forkel of the Department of Geodesy and Geoinformation at TU Wien. Winters are getting shorter and plants are turning green sooner. However, up to now, we were not clear about what this meant for plant growth in summer and autumn and for the amount of CO2 used during photosynthesis. For the first time, we have been able to investigate the global patterns of this effect by using satellite data. "We analysed satellite images from the past 30 years, examining the entire globe to the north of the 30th parallel north, from southern Europe and Japan to the most northerly tundra regions," says Matthias Forkel.In areas of high vegetation, light is strongly absorbed, and infrared radiation is strongly reflected. "This means that we can determine how much photosynthesis is occurring and how much carbon is taken up during photosynthesis across the globe on a point-by-point basis," explains Forkel. These data analyses were carried out at the University of Leeds in the UK and at TU Wien, with the additional involvement of climate and environmental research teams from the USA and several other countries.When spring-like weather starts earlier, it is reasonable to assume that plants will have more time to grow, absorb more carbon from the atmosphere and produce more biomass as a result. But this is not the case. The data does indeed show that the northern hemisphere is in fact greener in the spring when temperatures are especially warm. Yet this impact can be reversed in the summer and autumn, even leading to an overall reduction of carbon uptake as a result of the rise in temperature.There may be a range of reasons for this: greater plant growth in the spring may increase transpiration and the demand for water which in turn decreases soil moisture content and results in insufficient water being available to plants later in the year. It is possible that certain plants also have a predetermined growth period that is not extended by the earlier onset of growth."These mechanisms are complicated and vary on a regional basis," says Matthias Forkel. "However, our data clearly shows that average plant productivity decreases during years that experience a warm spring."Previous climate models did take into account plant growth, but they underestimated the role of this adverse effect. The models must therefore be improved. "Unfortunately, this changes climate forecasts for the worse," says Forkel. "We have to assume that the consequences of global warming will be even more dramatic than previously calculated."
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October 2, 2018
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https://www.sciencedaily.com/releases/2018/10/181002113959.htm
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Global warming increases wildfire potential damages in Mediterranean Europe
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A study published in
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"To draw this conclusion we combined regional climate projections with several empirical models linking the summer burned area to key climatic drivers," notes Marco Turco, UB researcher and first author of the study. "These results support the statement of the Paris Agreement (2015) that reports that limiting the temperature increase to 1.5ºC would "significantly reduce the risks and impacts of climate change," says the researcher.Fire seasons in 2017 and 2018 have been unusually high in several regions in Europe, with large wildfires in Greece, Portugal and Sweden, associated with intense droughts and heatwaves. These fires caused economic and ecological losses, and even human casualties.Marco Turco and his team used a series of regional climate models to project burned area in Mediterranean Europe, taking into account how the climate-vegetation-fire relationship will change under different scenarios due other factors such as droughts. The authors find that, with a 1.5ºC global warming, the burned area could increase by 40 % compared the projections that do not take into account future warming (mainly in the Iberian Peninsula). If warming is at 3ºC, it would increase by 100 %."These results, combined with the increase in societal exposure to large wildfires in recent years, call for a rethinking of current management strategies. Climate change effects could overcome fire prevention efforts, implying that more fire management efforts must be planned in the near future," says Marco Turco, researcher in the Group of Analysis of Adverse Weather Situations (GAMA) of the University of Barcelona, led by Carme Llasat, lecturer at the Department of Applied Physics of the UB. In this sense, the development of climate-fire models is crucial to identify key actions in adaptation strategies. In particular, combined with seasonal climate forecasts, these offer an under-exploited opportunity to prevent and reduce the fire impact of climate adverse conditions.Other collaborators in the study are researchers from the University of Murcia, University of Cantabria, the Institute of Geoscience and Earth Resources (IGG) of the Italian National Research Council and the company Intelligent Data Solutions (Santander).
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September 27, 2018
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https://www.sciencedaily.com/releases/2018/09/180927122939.htm
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2018 Arctic summertime sea ice minimum extent tied for sixth lowest on record
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Arctic sea ice likely reached its 2018 lowest extent on Sept. 19 and again on Sept. 23, according to NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder. Analysis of satellite data by NSIDC and NASA showed that, at 1.77 million square miles (4.59 million square kilometers), 2018 effectively tied with 2008 and 2010 for the sixth lowest summertime minimum extent in the satellite record.
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Arctic sea ice, the cap of frozen seawater blanketing most of the Arctic Ocean and neighboring seas in wintertime, follows seasonal patterns of growth and decay. It thickens and spreads during the fall and winter and thins and shrinks during the spring and summer. But in the past decades, increasing temperatures have led to prominent decreases in the Arctic sea ice extents, with particularly rapid decreases in the minimum summertime extent. The shrinking of the Arctic sea ice cover can ultimately affect the planet's weather patterns and the circulation of the oceans."This year's minimum is relatively high compared to the record low extent we saw in 2012, but it is still low compared to what it used to be in the 1970s, 1980s and even the 1990s," said Claire Parkinson, a climate change senior scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.Parkinson and her colleague Nick DiGirolamo calculated that, since the late 1970s, the Arctic sea ice extent has shrunk on average about 21,000 square miles (54,000 square kilometers) with each passing year. That is equivalent to losing a chunk of sea ice the size of Maryland and New Jersey combined every year for the past four decades.This summer, the weather conditions across the Arctic have been a mixed bag, with some areas experiencing warmer than average temperatures and rapid melt and other regions remaining cooler than normal, which leads to persistent patches of sea ice. Still, the 2018 minimum sea ice extent is 629,000 square miles (1.63 million square kilometers) below the 1981-2010 average of yearly minimum extents.One of the most unusual features of this year's melt season has been the reopening of a polynya-like hole in the icepack north of Greenland, where the oldest and thickest sea ice of the Arctic typically resides. In February of this year, a similar opening appeared in the same area, catching the attention of sea ice scientists everywhere. The first appearance of the hole raised concerns about the possibility that the region could became vulnerable if the original, thicker ice cover was replaced with thinner ice as the exposed seawater refroze. NASA's Operation IceBridge mission probed the area in March, finding that the ice was indeed thinner and thus more susceptible to be pushed around by the winds and ocean currents."This summer, the combination of thin ice and southerly warm winds helped break up and melt the sea ice in the region, reopening the hole," said Melinda Webster, a sea ice researcher with Goddard. "This opening matters for several reasons; for starters, the newly exposed water absorbs sunlight and warms up the ocean, which affects how quickly sea ice will grow in the following autumn. It also affects the local ecosystem; for example, it impacts seal and polar bear populations that rely on thicker, snow-covered sea ice for denning and hunting.Measurements of sea ice thickness, an important additional factor in determining the mass and volume changes of the sea ice cover, have been far less complete than the measurements of ice extent and distribution in the past four decades. Now, with the successful launch of NASA's Ice, Cloud and land Elevation Satellite-2, or ICESat-2, on Sept. 15, scientists will be able to use the data from the spacecraft's advanced laser altimeter to create detailed maps of sea ice thickness in both the Arctic and the Antarctic.
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