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September 11, 2017
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https://www.sciencedaily.com/releases/2017/09/170911122659.htm
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How openings in Antarctic sea ice affect worldwide climate
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In 1974, images acquired from NOAA satellites revealed a puzzling phenomenon: a 250,000 square kilometer opening in the winter sea ice in the Weddell Sea, south of South America. The opening, known as a polynya, persisted over three winters. Such expansive ice-free areas in the ocean surrounding Antarctica have not been seen since, though a small polynya was seen last year.
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In a new analysis of climate models, researchers from the University of Pennslyvania, Spain's Institute of Marine Sciences and Johns Hopkins University reveal the significant global effects that these seemingly anomalous polynyas can have. Their findings indicate that heat escaping from the ocean through these openings impacts sea and atmospheric temperatures and wind patterns around the globe and even rainfall around the tropics. Though this process is part of a natural pattern of climate variability, it has implications for how the global climate will respond to future anthropogenic warming."This small, isolated opening in the sea ice in the Southern Ocean can have significant, large-scale climate implications," said Irina Marinov, a study author and assistant professor in Penn's Department of Earth and Enviromental Science in the School of Arts & Sciences. "Climate models suggest that, in years and decades with a large polynya, the entire atmosphere warms globally, and we see changes in the winds in the Southern Hemisphere and a southward shift in the equatorial rain belt. This is attributable to the polynya."The study appears in the Typically, the Southern Ocean is covered in ice during the Southern Hemisphere'swinter. Polynyas occur when warm subsurface waters of North Atlantic and equatorial origin mix locally with cold surface waters, a process known as open-ocean convection.Until recently, climate scientists and oceanographers believed that atmospheric and ocean conditions around the tropics were the primary drivers in affecting conditions outside the tropics. But in the last few years, Marinov and collaborators and others have shown that the opposite is also true: the Southern Ocean has an important role in affecting tropical and Northern Hemisphere climates.In the current work, Marinov and colleagues used powerful models that simulate past and future climate to determine how the effects of polynya ripple out around the globe.Their model indicated that polynyas and accompanying open-ocean convection occur roughly every 75 years. When they occur, the researchers observed, they act as a release valve for the ocean's heat. Not only does the immediate area warm, but there are also increases in overall sea-surface and atmospheric temperatures of the entire Southern Hemisphere and, to a lesser extent, the Northern Hemisphere, as well.Changes in north-south temperature gradients lead to changes in wind patterns as well."We are seeing a decrease in what we call the Southern Hemisphere westerlies and changes in trade winds," Marinov said. "And these winds affect storms, precipitation and clouds."Among these changes in precipitation is a shift in the Intertropical Convergence Zone, an equatorial belt where trade winds converge, resulting in intense precipitation. When a polynya occurs, this rain belt moves south a few degrees and stays there for 20 to 30 years before shifting back."This affects water resources in, for example, Indonesia, South America and sub-Saharan Africa," said Marinov. "We have a natural variation in climate that may be, among other effects, impacting agricultural production in heavily populated regions of the world."Given these broad-scale implications of a Southern Ocean phenomenon, Marinov underscores the need to increase monitoring in the region. She is part of an effort called SOCCOM, for Southern Ocean Carbon and Climate Observations and Modeling, placing robotic floats in the Southern Ocean to collect data on ocean temperature, salinity, carbon, nutrients and oxygen."We're also urging people to keep a close eye on the satellites to look for other polynyas, this year and going forward," Marinov said.Earlier research by Marinov's group and collaborators suggested that, under climate change, polynyas may become less frequent. As sea ice melts it freshens the top layer of the sea surface, making it lighter and less likely to mix with the heavier bottom waters. Marinov notes that the fact that no significant polynyas opened up from the mid-1970s until last year may have contributed to the so-called "climate hiatus" in the late 1990s and early 2000s, when global average surface temperatures appeared to stall in their otherwise persistent upward climb."During this hiatus period abnormal amounts of heat were stored in the subsurface ocean waters" Marinov said. "Most research has attributed this hiatus to a prolonged La Niña period, resulting in a storage of heat in the low-latitude Pacific. But I think that a lack of a Weddell Sea polynya also contributed, storing more heat in the Southern Ocean and preventing the additional release of heat to the atmosphere."The work raises many new questions, such as how a decreasing sea ice extent, including the recent breaking off of a massive chunk of the Antarctic peninsula, will affect the frequency of polynyas and how the presence or absence of polynyas will affect how much atmospheric temperatures warm in response to anthropogenic climate change."This investigating into polynyas and Southern Ocean convection turned out to be a very important and interesting story for the global climate that we think a lot of people will be studying in the next decade," Marinov said.
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September 5, 2017
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https://www.sciencedaily.com/releases/2017/09/170905123218.htm
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Warmer world may bring more local, less global, temperature variability
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Many tropical or subtropical regions could see sharp increases in natural temperature variability as Earth's climate warms over coming decades, a new Duke University-led study suggests.
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These local changes could occur even though Earth's global mean surface air temperature (GMST) is likely to become less variable, the study shows."This new finding runs counter to the popular notion that as the climate warms, temperature variability will increase and weather will get more volatile everywhere," said Patrick T. Brown, a postdoctoral research scientist at the Carnegie Institution for Science, who led the study while he was a doctoral student at Duke's Nicholas School of the Environment."Our research suggests a different scenario: Global unforced temperature variability will actually decrease, not increase, as Earth warms, but local decade-to-decade variability could increase by as much as 50 percent in some places," Brown said.Unforced, or natural, temperature variability can be caused by interactions between the atmosphere, ocean currents and sea ice. These fluctuations can either mask or exacerbate human-caused climate change for a decade or two at a time, he noted.Because billions of people live in tropical or subtropical regions that may experience increased temperature variability, and because these regions are critical for biodiversity, food production and climate regulation, "it's vital that we understand the magnitude of unforced decade-to-decade variability that could occur there, and the mechanisms that drive it," he said.Brown and his colleagues published their peer-reviewed paper Sept. 4 in the journal To conduct the study, they first inspected a climate model run under pre-industrial conditions. The model, which was developed at NOAA's Geophysical Fluid Dynamics Laboratory, simulates climate under perpetual atmospheric conditions similar to those experienced on Earth before the widespread emission of industrial greenhouse gasses. This allows scientists to get a clearer picture of the forces that cause variability in the absence of human drivers."To isolate unforced variability, we looked at the model's output without changing any of its environment parameters, such as atmospheric carbon dioxide levels, solar radiation or volcanic activity, over a theoretical 900-year timespan," Brown explained.On the second run, the scientists doubled the model's atmospheric carbon dioxide levels to simulate projected future conditions."In the doubled-COConsistent results were obtained using similar experiments on other climate models.What's happening, Brown said, is as Earth warms because of increasing CO"Albedo feedback is a large contributor to decade-to-decade unforced variability. When Earth's atmosphere naturally gets a bit warmer, more of the reflective sea ice at high latitudes melts. This exposes more water, which absorbs solar energy and amplifies the initial warming, enhancing the GMST variability," he explained. "But we found that when you double the COThe end result is less variability globally -- especially in the high latitudes -- but more variability in the tropics."This suggests that the pre-industrial control runs we have been using are not ideal for studying what unforced variability will look like in the future," said Wenhong Li, associate professor of climate at Duke's Nicholas School. "But it might inspire more modeling groups to run models under perpetual conditions that reflect what we expect in the future."
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August 31, 2017
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https://www.sciencedaily.com/releases/2017/08/170831151303.htm
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Coming soon to Montreal: The infrastructure cost of climate change
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It's sunny in downtown Montreal and pouring rain at the airport. Such events will be more likely in the future.
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The climate of the city is changing and will continue to do so at a rapidly increasing rate and with much more spatial variability in the future.That's according to new research from Concordia's Department of Building, Civil and Environmental Engineering.MASc student Pablo Jaramillo and assistant professor Ali Nazemi recently published a study on water security in Using the Greater Montreal Area and its neighbouring regions for their case study, the researchers compiled observed data recorded at eight local weather stations from 1950 to 2006. They then compared it to data yielded from the NASA data set for the same period and common temporal and spatial scales.They found significant trends in the city's climate, which can be captured fairly well by the downscaled data.Comparing the projected trends from 2006 to 2099 with past observed trends, they showed that the Montreal region's climate will continue to change at a faster, more intense rate and with more pronounced spatio-temporal variability."This means that we will see more differences in the long-term climate over the Island of Montreal and its neighbouring regions," says Nazemi, the study's lead researcher."We can clearly see more variability in climate characteristics, such as extreme rainfall and temperature, as well as the number of days with extreme hot or cold temperature over the same region."According to Nazemi, this finding will have huge implications for urban management."Climate plays a key role in the design and operation of urban infrastructure and to a large extent determines water and energy demands. As a result, changes in climate conditions will have direct impacts on how we design almost any aspect of the city, from its drainage system to its energy use," he explains."Most of the time, we consider a single value in relation to the design of these systems and we assume that this value will remain unchanged during the infrastructure's lifespan, Nazemi adds."We already know that this is not the case anymore due to climate change; but as the spatial variance in the projected changes in our climate also increases, the current approach of one-size-fits-all will no longer be feasible. For instance, a sewage system designed to prevent flooding in downtown Montreal may fail to prevent flooding in Dorval."Accordingly, one of the main takeaways of the study is that urban management should move toward local design and management as opposed to city-wide solutions to climate change impacts.In addition, while the findings confirm that downscaled models can reproduce observed rates of change in the historical climate of a city, the discrepancies in the long-term climate conditions limit the applicability of the downscaled climate projections.For Nazemi, this points to the need for more robust technology for the assessment of climate change impacts at the local level."Whether the downscaled climate projections can adequately inform climate impact assessments in a city like Montreal depends on the type of management problem and the resulting decisions," he says."Because of some limitations, we advocate considering more holistic frameworks. These approaches should ideally be applied in conjunction with acclaimed top-down approaches to support climate change vulnerability assessment in Montreal until improved climate modelling capability becomes available."
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| 2,017 |
August 31, 2017
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https://www.sciencedaily.com/releases/2017/08/170831092650.htm
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Record-low 2016 Antarctic sea ice due to 'perfect storm' of tropical, polar conditions
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While winter sea ice in the Arctic is declining so dramatically that ships can now navigate those waters without any icebreaker escort, the scene in the Southern Hemisphere is very different. Sea ice area around Antarctica has actually increased slightly in winter -- that is, until last year.
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A dramatic drop in Antarctic sea ice almost a year ago, during the Southern Hemisphere spring, brought its maximum area down to its lowest level in 40 years of record keeping. Ocean temperatures were also unusually warm. This exceptional, sudden nosedive in Antarctica differs from the long-term decline in the Northern Hemisphere. A new University of Washington study shows that the lack of Antarctic sea ice in 2016 was in part due to a unique one-two punch from atmospheric conditions both in the tropical Pacific Ocean and around the South Pole.The study was published Aug. 24 in "This combination of factors, all these things coming together in a single year, was basically the 'perfect storm,' for Antarctic sea ice," said corresponding author Malte Stuecker, a UW postdoctoral researcher in atmospheric sciences. "While we expect a slow decline in the future from global warming, we don't expect such a rapid decline in a single year to happen very often."The area of sea ice around Antarctica at its peak in late 2016 was 2 million square kilometers (about 800,000 square miles) less than the average from the satellite record. Statistically, this is three standard deviations away from the average -- an event that would be expected to occur randomly just once every 300 years.The record low was not predicted by climate scientists, so UW researchers looked at the bigger picture in ocean and atmospheric data to explain why it happened.The previous year, 2015-16, had a very strong El Niño in the tropical Pacific Ocean. Nicknamed the "Godzilla El Nino," the event was similar to other monster El Niños in 1982-83 and 1997-98. Unlike the 1997-98 event, however, it was only followed by a relatively weak La Niña in 2016.Far away from the tropics, the tropical El Niño pattern creates a series of high- and low-pressure zones that cause unusually warm ocean temperatures in Antarctica's eastern Ross, Amundsen and Bellingshausen seas. But in 2016, when no strong La Niña materialized, researchers found that these unusually warm surface pools lingered longer than usual and affected freeze-up of seawater the following season."I've spent many years working on tropical climate and El Niño, and it amazes me to see its far-reaching impacts," Stuecker said.Meanwhile, observations show that the winds circling Antarctica were unusually weak in 2016, meaning they did not push sea ice away from the Antarctic coast to make room for the formation of new ice. This affected ice formation around much of the Southern Ocean."This was a really rare combination of events, something that we have never seen before in the observations," Stuecker said.The researchers analyzed 13,000 years of climate model simulations to study how these unique conditions would affect the sea ice. Taken together, the El Niño pattern and Southern Ocean winds explain about two-thirds of the 2016 decline. The rest may be due to unusually big storms, which a previous paper suggested had broken up ice floes.Scientists predict Antarctica's ocean will be one of the last places on Earth to experience global warming. Eventually the Southern Ocean's surface will begin to warm, however, and then sea ice there will begin its more long-term decline."Our best estimate of the Antarctic sea ice turnaround point is sometime in the next decade, but with high uncertainty because the climate signal is small compared to the large variations that can occur from one year to the next," said co-author Cecilia Bitz, a UW professor of atmospheric sciences.Stuecker noted that this type of big, rare weather event is useful to help understand the physics behind sea ice formation, and to learn how best to explain the observations."For understanding the climate system we must combine the atmosphere, ocean and ice, but we must focus on more than a specific region," Stuecker said. "If we want to understand sea ice in Antarctica, we cannot just zoom in locally -- we really have to take a global perspective."
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Weather
| 2,017 |
August 29, 2017
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https://www.sciencedaily.com/releases/2017/08/170829091046.htm
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Research in ancient forests show link between climate change and wildfires
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Portland State researchers studying centuries-old trees in South America have found a tight correlation between wildfires and a warm weather fluctuation that has become more frequent in recent decades -- and will continue to be more frequent as the climate warms.
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PSU geography professor Andrés Holz and his research team first discovered the correlation in 2011. Since then, the team fine-tuned and expanded the geographic scope of their discovery by studying 1,767 fire-scarred trees from 97 South American sites, encompassing multiple ecosystems. It is the largest network of fire-scarred trees outside the United States. Some of the trees dated back to 990 A.D., which gave the researchers a year-by-year, decade-by-decade view of fire activity.It also provided a living record of how the fires corresponded with the weather fluctuation. The warm, dry weather was triggered by a climate oscillation called the Southern Annular Mode (SAM), a change in westerly wind patterns throughout the Southern Hemisphere."We found that wildfire activity over the centuries has been increasingly favored by the warm phases of SAM going back to 1665," Holz said.He said SAM-related wildfires became more frequent in the 20th Century. Holz said climate modeling studies show the trend will accelerate in the 21st Century due to an increase in greenhouse gasses, setting the stage for more frequent wildfires.Their newest findings were recently published in
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Weather
| 2,017 |
August 24, 2017
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https://www.sciencedaily.com/releases/2017/08/170824090103.htm
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Severity of North Pacific storms at highest point in over 1,200 years
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The intensification of winter storm activity in Alaska and Northwestern Canada started close to 300 years ago and is unprecedented in magnitude and duration over the past millennium, according to a new study from Dartmouth College.
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The research, an analysis of sea salt sodium levels in mountain ice cores, finds that warming sea surface temperatures in the tropical Pacific Ocean have intensified the Aleutian Low pressure system that drives storm activity in the North Pacific.The current period of storm intensification is found to have begun in 1741. According to researchers, additional future warming of tropical Pacific waters -- due in part to human activity -- should continue the long-term storminess trend."The North Pacific is very sensitive to what happens in the tropics," said Erich Osterberg, an assistant professor of earth sciences at Dartmouth College. "It is more stormy in Alaska now than at any time in the last 1200 years, and that is driven by tropical ocean warming."While the Aleutian Low pressure system sits over Southcentral Alaska in the winter, it can impact weather across the North American continent."Storminess in the North Pacific not only impacts Alaska and Northwestern Canada, it creates colder, wetter and stormier weather as far away as Florida," said Osterberg.The analysis focuses on two ice cores drilled in 2013 from Mount Hunter in Alaska's Denali National Park, and an older ice core from Canada's Mount Logan. The ice cores, each measuring over 600-feet long, offer glimpses into over a thousand years of climate history in the North Pacific through sea salt blown into the atmosphere by winter ocean storms.The two ice cores from Denali benefited from high levels of snowfall, providing what Osterberg says is "amazing reproducibility" of the climate record and giving the researchers exceptional confidence in the study results."That's the other remarkable thing about this research," said Osterberg, "not only are we seeing strong agreement between the two Denali cores, we are finding the same story of intensified storminess recorded in ice cores collected 13 years and 400 miles apart."While 1741 is noted as the year the current intensification began, the paper also references an increase in storminess in the year 1825. According to the paper, warmer tropical waters since the mid-18th century can be the result of both natural variability and human-driven climate changes."There is no doubt that warming tropical ocean temperatures over the last 50 years is mostly caused by human activity," said Osterberg, "a really interesting question is when you go back over hundreds of years, how much of that is anthropogenic?"Beyond human activity, tropical sea surface temperatures further back in time are affected by volcanic eruptions, changes in the intensity of sunlight and natural events like El Niño."The reality of the science is that our changing climate is driven by human causes on top of natural cycles, and we have to disentangle these things," said Osterberg. "This becomes even more critical when predicting climate change over a specific region like Alaska instead of the whole globe averaged together."Researchers are still waiting to analyze the last 10 meters of the Denali ice cores. The remaining portions could offer information on thousands more years of climate history, but are so compressed that they will require the use of advanced laser tools.
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Weather
| 2,017 |
August 23, 2017
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https://www.sciencedaily.com/releases/2017/08/170823091001.htm
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Genetic map reveals heat tolerance traits in peas
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Farmers across the world produce between 10 and 13 million tons of field pea every year. That makes it a top legume crop, just behind dry beans and chickpeas.
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But as the global climate changes and temperatures continue to rise, heat stress is becoming a major limiting factor for pea cultivation.A new study indicates that pea plants with some specific traits -- such as longer flowering time and higher pod numbers -- may be more resistant to heat stress.The researchers also gained new insights into the genetics of heat tolerance in pea."In some years, the older varieties of pea weren't growing very well because of heat stress," says Rosalind Bueckert, lead author of the study. "We wanted to find new varieties that have robust and consistent yields in a warming world."According to Bueckert, a plant scientist at the University of Saskatchewan, "tolerance to heat stress in peas seems to be dependent on quite a few traits." The study found that two traits, however, are most important: higher pod numbers and longer flowering duration.Bueckert and her colleagues Tom Warkentin and Shaoming Huang are the first to uncover the location of genes that affect heat stress."Heat stress means fewer flowers, fewer pods, and ultimately, lower yields," says Bueckert. Varieties of pea that have more pods to begin with have higher yields after a heat-stress event.Similarly, "if a pea variety flowers for a longer time, it has more opportunities to have a higher yield, even under heat stress," says Bueckert. That's because the plant has more time to recover from extreme weather events during flowering.But too long of a flowering time can lead to other problems. "You need the right balance of the vegetative and reproductive phases," says Bueckert.To determine which traits are important for heat resistance in peas, Bueckert and her colleagues crossed two commonly used varieties of pea, CDC Centennial and CDC Sage. Then the researchers evaluated more than a hundred new varieties of pea derived from this cross."By crossing two different varieties of pea, you may be able to breed offspring with traits beyond those of either parent," says Bueckert. For example, some of the offspring tested in this study were more heat-resistant than either CDC Sage or CDC Centennial.The researchers cultivated these new varieties of pea for two growing seasons in Saskatchewan.One batch was seeded at a typical time for pea cultivation, mid-May. A second batch was started in early June. These plants flowered later in the year when temperatures are higher. This allowed the researchers to test for pea varieties that grew better and had higher yields in warmer weather."Identifying traits that make pea plants more resistant to heat stress is one piece of the puzzle," says Bueckert. The other piece is better understanding the genetics of these traits.Traditionally, researchers used visible traits, such as pod number, to select crop varieties that grow well in specific environments. However, mapping out the pertinent genetic information helps focus the work. Researchers can identify specific genetic locations for a trait within the pea's genetic map. From there, researchers can more reliably select crop varieties."The more work we can do with genetic locations and molecular techniques, the more efficient we will be," says Bueckert.While flowering duration and pod number are the two most important traits for heat resistance in peas, the researchers are also examining other traits that can contribute. For example, "semi-leafless varieties of pea are better at dealing with heat stress than leafy varieties," says Bueckert.Future research will aim to identify more of these traits, and further increase our understanding of the genetic basis of heat resistance in peas.
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Weather
| 2,017 |
August 19, 2017
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https://www.sciencedaily.com/releases/2017/08/170819103700.htm
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Wood frogs research clarifies risks posed to animals by warming climate
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As conditions warm, fish and wildlife living at the southern edge of their species' ranges are most at risk, according to Penn State researchers who led a major collaborative study of how wood frogs are being affected by climate change.
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However, determining which species and which populations are in danger of declining or disappearing is not simple or straightforward, according to researcher David Miller, assistant professor of wildlife population ecology, College of Agricultural Sciences. Local and regional precipitation trends are nearly as important as temperature in determining the fate of many animals, he explained, and that's especially true with moisture-sensitive creatures such as amphibians.Miller's lab spearheaded the study that included 14 universities, the U.S. Geological Survey, and several other state and federal agencies, looking at long-term monitoring data from 746 wood frog populations in 27 study areas, from Tennessee to Canada. The research focused on how climatic variation affected population growth rates and how these relationships varied with respect to long-term climate.In many of the wood frog populations studied, researchers found evidence of interacting temperature and precipitation influencing population size, such as warmer summers having less of a negative effect in areas that received more precipitation. Some of the findings, which were published early online in As anticipated, researchers saw wood frog populations that seemed to be suffering from warmer than normal summer temperatures in hotter areas in the southern part of the range. Similarly, they found higher than average rainfall in areas that typically experience lower annual rainfall saw positive effects on wood frog population growth.But other results were contrary to expectations, such as positive effects of higher than normal rainfall in wetter parts of the range and positive responses to winter warming, especially in milder areas. In general, researchers found wood frogs were more sensitive to changes in temperature or temperature interacting with precipitation than to changes in precipitation alone.Northward shifts in wildlife ranges may be expected in coming years or decades, noted lead researcher Staci Amburgey, a doctoral degree student in ecology, but that trend may depend nearly as much on demographic weather patterns as warming temperatures. And in the case of wood frogs, other factors are also at play.The study's results suggest that sensitivity to changes in climate cannot be predicted simply by knowing locations within the species' climate envelope, she pointed out. Many climate processes did not affect population growth rates as expected, based on range position. Processes such as species interactions, local adaptation and interactions with the physical landscape likely affect the responses researchers observed."Wood frogs are really broadly distributed, so I don't think the species is going to be declining anytime soon," said Amburgey, who started studying amphibians when she was an undergraduate and master's degree student at Colorado State. "But having said that, it appears that populations in the southern portion of the wood frog's range are vulnerable if we have more hot, dry summers. Certainly frogs in the southern part of their range are more sensitive to hot years than frogs farther north, where the conditions will not push their physiological tolerances."This study was novel because researchers did not simply document where wood frogs exist and where they do not, Amburgey explained. Instead, they analyzed reproduction rates by counting egg masses in spring pools to determine where the amphibian's populations were growing or declining -- trying to determine how each population was responding to year-to-year differences in climate.Wood frogs are an ideal species to study to develop predictions about how animals will respond to warming conditions, Miller believes. They are cold-weather frogs with a range that extends farther north than other amphibians. As such, they have evolved with some amazing adaptations, not the least of which is the ability to survive freezing solid in winters."In a warming world, wood frogs at the southern end of their range may be in trouble," he said. "By freezing solid, they thrive as far north as Alaska. They spend winters near the surface, and they are one of the first species to come out when things thaw. Then they head immediately to small wetlands in the forest that tend to dry out during the summer to breed, and their tadpoles develop really quickly and get out into the woods early. They are an important part of our forested ecosystems in the Northeast and a truly unique species."
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| 2,017 |
August 18, 2017
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https://www.sciencedaily.com/releases/2017/08/170818092154.htm
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Spoiler alert: Computer simulations provide preview of upcoming eclipse
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A research team from Predictive Science Inc. (PSI) used the Stampede2 supercomputer at The University of Texas at Austin's Texas Advanced Computing Center (TACC) to forecast the corona of the sun during the upcoming eclipse. The findings shed light on what the eclipse of the sun might look like Aug. 21 when it will be visible across much of the U.S., tracing a 70-mile-wide band across 14 states.
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Beyond their rarity, solar eclipses help astronomers better understand the sun's structure, inner workings and the space weather it generates.The researchers completed a series of highly detailed solar simulations timed to the moment of the eclipse using TACC's Stampede2, Comet at the San Diego Supercomputer Center, and NASA's Pleiades supercomputer. They modeled the sun's surface and predicted what the solar corona -- the aura of plasma that surrounds the sun and extends millions of kilometers into space -- will look like during this eclipse."Advanced computational resources are crucial to developing detailed physical models of the solar corona and solar wind," said Jon Linker, president and senior research scientist of PSI. "The growth in the power of these resources in recent years has fueled an increase in not only the resolution of these models, but the sophistication of the way the models treat the underlying physical processes as well."The researchers' computer simulations were converted into scientific visualizations that approximate what the human eye might see during the solar eclipse.The simulations are among the largest the research group has performed, using 65 million grid points to provide great accuracy and realism.A collection of the images can be found here and here.The team used data collected by the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory and a combination of magnetic field maps, solar rotation rates and mathematical models of how magnetohydrodynamics (the interplay of electrically conducting fluids such as plasmas and magnetic fields) affect the corona.Predictions about the appearance of the corona during an eclipse test complex, three-dimensional computational models of the sun against visible reality.Doing so improves the accuracy of predicting space weather, which could have important practical ramifications. If a powerful solar storm such as the 1859 Carrington Event -- which led to auroras being visible as far south as the Caribbean and caused telegraphs to short and catch fire -- were to hit Earth today, it would cause more than $2 trillion in damages, according a National Academy of Sciences report.Predicting the arrival of such a solar storm in advance would allow officials to take the most critical electronic infrastructure offline and limit the storm's impact. But doing so requires understanding how the visible surface of the sun (the corona) relates to the mass ejections of plasma that cause space weather."With the ability to more accurately model solar plasmas, researchers will be able to better predict and reduce the impacts of space weather on key pieces of infrastructure that drive today's digital world," said Niall Gaffney, a former Hubble Space Telescope scientist and director of data intensive computing at TACC.The researchers will present their results at the Solar Physics Division meeting of the American Astronomical Society on Aug. 22-24.The research was supported by NASA, the Air Force Office of Scientific Research and the National Science Foundation.
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Weather
| 2,017 |
August 14, 2017
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https://www.sciencedaily.com/releases/2017/08/170814092941.htm
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Urban floods intensifying, countryside drying up
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An exhaustive global analysis of rainfall and rivers shows signs of a radical shift in streamflow patterns, with more intense flooding in cities and smaller catchments coupled with a drier countryside.
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Drier soils and reduced water flow in rural areas -- but more intense rainfall that overwhelms infrastructure and causes flooding and stormwater overflow in urban centres. That's the finding of an exhaustive study of the world's river systems, based on data collected from more than 43,000 rainfall stations and 5,300 river monitoring sites across 160 countries.The study, by engineers at University of New South Wales in Sydney and which appears in the latest issue of the journal As expected, it found warmer temperatures lead to more intense storms, which makes sense: a warming atmosphere means warmer air, and warmer air can store more moisture. So when the rains do come, there is a lot more water in the air to fall, and hence, rainfall is more intense.But there's been a growing puzzle: why is flooding not increasing at the same rate as the higher rainfall?The answer turned out to be the other facet of rising temperatures: more evaporation from moist soils is causing them to become drier before any new rain occurs -- moist soils that are needed in rural areas to sustain vegetation and livestock. Meanwhile, small catchments and urban areas, where there are limited expanses of soil to capture and retain moisture, the same intense downpours become equally intense floods, overwhelming stormwater infrastructure and disrupting life."Once we sorted through the masses of data, this pattern was very clear," said Ashish Sharma, a professor of hydrology at UNSW's School of Civil and Environmental Engineering. "The fact that we relied on observed flow and rainfall data from across the world, instead of uncertain model simulations, means we are seeing a real-world effect -- one that was not at all apparent before.""It's a double whammy," said Conrad Wasko, lead author of the paper and postdoctoral fellow at UNSW's Water Research Centre. "People are increasingly migrating to cities, where flooding is getting worse. At the same time, we need adequate flows in rural areas to sustain the agriculture to supply these burgeoning urban populations."Global flood damage cost more than US$50 billion in 2013; this is expected to more than double in the next 20 years as extreme storms and rainfall intensify and growing numbers of people move into urban centres. Meanwhile, global population over the next 20 years is forecast to rise another 23% from today's 7.3 billion to 9 billion -- requiring added productivity and hence greater water security. The reduction in flows noted by this study makes this an even bigger challenge than before."We need to adapt to this emerging reality," said Sharma. "We may need to do what was done to make previously uninhabitable places liveable: engineer catchments to ensure stable and controlled access to water. Places such as California, or much of the Netherlands, thrive due to extensive civil engineering. Perhaps a similar effort is needed to deal with the consequences of a changing climate as we enter an era where water availability is not as reliable as before.""Climate change keeps delivering us unpleasant surprises," said Mark Hoffman, UNSW's Dean of Engineering. "Nevertheless, as engineers, our role is to identify the problem and develop solutions. Knowing the problem is often half the battle, and this study has definitely identified a major one."Rainfall data used in the study was collected from the Global Historical Climatology Network, which contains records from over 100,000 weather stations in 180 countries and is managed by the U.S. National Oceanic and Atmospheric Administration. River flow data came from the Global Runoff Database, run by Germany's Federal Institute of Hydrology, which relies on river discharge information collected daily or monthly from more than 9,300 stations in 160 countries.
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Weather
| 2,017 |
August 10, 2017
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https://www.sciencedaily.com/releases/2017/08/170810145707.htm
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Day to night and back again: Earth's ionosphere during the total solar eclipse
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On Aug. 21, 2017, the Moon will slide in front of the Sun and for a brief moment, day will melt into a dusky night. Moving across the country, the Moon's shadow will block the Sun's light, and weather permitting, those within the path of totality will be treated to a view of the Sun's outer atmosphere, called the corona.
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But the total solar eclipse will also have imperceptible effects, such as the sudden loss of extreme ultraviolet radiation from the Sun, which generates the ionized layer of Earth's atmosphere, called the ionosphere. This ever-changing region grows and shrinks based on solar conditions, and is the focus of several NASA-funded science teams that will use the eclipse as a ready-made experiment, courtesy of nature.NASA is taking advantage of the Aug. 21 eclipse by funding 11 ground-based science investigations across the United States. Three of these will look to the ionosphere in order to improve our understanding of the Sun's relationship to this region, where satellites orbit and radio signals are reflected back toward the Earth."The eclipse turns off the ionosphere's source of high-energy radiation," said Bob Marshall, a space scientist at University of Colorado Boulder and principal investigator for one of the studies. "Without ionizing radiation, the ionosphere will relax, going from daytime conditions to nighttime conditions and then back again after the eclipse."Stretching from roughly 50 to 400 miles above Earth's surface, the tenuous ionosphere is an electrified layer of the atmosphere that reacts to changes from both Earth below and space above. Such changes in the lower atmosphere or space weather can manifest as disruptions in the ionosphere that can interfere with communication and navigation signals."In our lifetime, this is the best eclipse to see," said Greg Earle, an electrical and computer engineer at Virginia Tech in Blacksburg, Virginia, who is leading another of the studies. "But we've also got a denser network of satellites, GPS and radio traffic than ever before. It's the first time we'll have such a wealth of information to study the effects of this eclipse; we'll be drowning in data."Pinning down ionospheric dynamics can be tricky. "Compared to visible light, the Sun's extreme ultraviolet output is highly variable," said Phil Erickson, a principal investigator of a third study and space scientist at Massachusetts Institute of Technology's Haystack Observatory in Westford, Massachusetts. "That creates variability in ionospheric weather. Because our planet has a strong magnetic field, charged particles are also affected along magnetic field lines all over the planet -- all of this means the ionosphere is complicated."But when totality hits on Aug. 21, scientists will know exactly how much solar radiation is blocked, the area of land it's blocked over and for how long. Combined with measurements of the ionosphere during the eclipse, they'll have information on both the solar input and corresponding ionosphere response, enabling them to study the mechanisms underlying ionospheric changes better than ever before.Tying the three studies together is the use of automated communication or navigation signals to probe the ionosphere's behavior during the eclipse. During typical day-night cycles, the concentration of charged atmospheric particles, or plasma, waxes and wanes with the Sun."In the daytime, ionospheric plasma is dense," Earle said. "When the Sun sets, production goes away, charged particles recombine gradually through the night and density drops. During the eclipse, we're expecting that process in a much shorter interval."The denser the plasma, the more likely these signals are to bump into charged particles along their way from the signal transmitter to receiver. These interactions refract, or bend, the path taken by the signals. In the eclipse-induced artificial night the scientists expect stronger signals, since the atmosphere and ionosphere will absorb less of the transmitted energy."If we set up a receiver somewhere, measurements at that location provide information on the part of the ionosphere between the transmitter and receiver," Marshall said. "We use the receivers to monitor the phase and amplitude of the signal. When the signal wiggles up and down, that's entirely produced by changes in the ionosphere."Using a range of different electromagnetic signals, each of the teams will send signals back and forth across the path of totality. By monitoring how their signals propagate from transmitter to receiver, they can map out changes in ionospheric density. The teams will also use these techniques to collect data before and after the eclipse, so they can compare the well-defined eclipse response to the region's baseline behavior, allowing them to discern the eclipse-related effects.The ionosphere is roughly divided into three regions in altitude based on what wavelength of solar radiation is absorbed: the D, E and F, with D being the lowermost region and F, the uppermost. In combination, the three experiment teams will study the entirety of the ionosphere.Marshall and his team, from the University of Colorado Boulder, will probe the D-region's response to the eclipse with very low frequency, or VLF, radio signals. This is the lowest and least dense part of the ionosphere -- and because of that, the least understood."Just because the density is low, doesn't mean it's unimportant," Marshall said. "The D-region has implications for communications systems actively used by many military, naval and engineering operations."Marshall's team will take advantage of the U.S. Navy's existing network of powerful VLF transmitters to examine the D-region's response to changes in solar output. Radio wave transmissions sent from Lamoure, North Dakota, will be monitored at receiving stations across the eclipse path in Boulder, Colorado, and Bear Lake, Utah. They plan to combine their data with observations from several space-based missions, including NOAA's Geostationary Operational Environmental Satellite, NASA's Solar Dynamics Observatory and NASA's Ramaty High Energy Solar Spectroscopic Imager, to characterize the effect of the Sun's radiation on this particular region of the ionosphere.Erickson and team will look further up, to the E- and F-regions of the ionosphere. Using over 6,000 ground-based GPS sensors alongside powerful radar systems at MIT's Haystack Observatory and Arecibo Observatory in Puerto Rico, along with data from several NASA space-based missions, the MIT-based team will also work with citizen radio scientists who will send radio signals back and forth over long distances across the path.MIT's science team will use their data to track travelling ionospheric disturbances -- which are sometimes responsible for space weather patterns in the upper atmosphere -- and their large-scale effects. These disturbances in the ionosphere are often linked to a phenomenon known as atmospheric gravity waves, which can also be triggered by eclipses."We may even see global-scale effects," Erickson said. "Earth's magnetic field is like a wire that connects two different hemispheres together. Whenever electrical variations happen in one hemisphere, they show up in the other."Earle and his Virginia Tech-based team will station themselves across the country in Bend, Oregon; Holton, Kansas; and Shaw Air Force Base in Sumter, South Carolina. Using state-of-the-art transceiver instruments called ionosondes, they will measure the ionosphere's height and density, and combine their measurements with data from a nation-wide GPS network and signals from the ham radio Reverse Beacon Network. The team will also utilize data from SuperDARN high frequency radars, two of which lie along the eclipse path in Christmas Valley, Oregon, and Hays, Kansas."We're looking at the bottom side of the F-region, and how it changes during the eclipse," Earle said. "This is the part of the ionosphere where changes in signal propagation are strong." Their work could one day help mitigate disturbances to radio signal propagation, which can affect AM broadcasts, ham radio and GPS signals.Ultimately, the scientists plan to use their data to improve models of ionospheric dynamics. With these unprecedented data sets, they hope to better our understanding of this perplexing region."Others have studied eclipses throughout the years, but with more instrumentation, we keep getting better at our ability to measure the ionosphere," Erickson said. "It usually uncovers questions we never thought to ask."For more information on the upcoming total solar eclipse:
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Weather
| 2,017 |
August 10, 2017
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https://www.sciencedaily.com/releases/2017/08/170810104949.htm
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Human-caused warming likely led to recent streak of record-breaking temperatures
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It is "extremely unlikely" 2014, 2015 and 2016 would have been the warmest consecutive years on record without the influence of human-caused climate change, according to the authors of a new study.
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Temperature records were first broken in 2014, when that year became the hottest year since global temperature records began in 1880. These temperatures were then surpassed in 2015 and 2016, making last year the hottest year ever recorded. In 2016, the average global temperature across land and ocean surface areas was 0.94 degrees Celsius (1.69 degrees Fahrenheit) above the 20th century average of 13.9 degrees Celsius (57.0 degrees Fahrenheit), according to NOAA.Combining historical temperature data and state-of-the-art climate model simulations, the new study finds the likelihood of experiencing consecutive record-breaking global temperatures from 2014 to 2016 without the effects of human-caused climate change is no greater than 0.03 percent and the likelihood of three consecutive record-breaking years happening any time since 2000 is no more than 0.7 percent. When anthropogenic warming is considered, the likelihood of three consecutive record-breaking years happening any time since 2000 rises to as high as 50 percent, according to the new study.That means human-caused climate change is very likely to blame for the three consecutive record-hot years, according to the new study accepted for publication in "With climate change, this is the kind of thing we would expect to see. And without climate change, we really would not expect to see it," said Michael Mann, a climate scientist at Pennsylvania State University in State College, Pennsylvania, and lead author of the new study.Greenhouse gases, like carbon dioxide and methane, accumulate in the atmosphere and trap heat that would otherwise escape into space. Excess greenhouse gases from industrial activities, like burning fossil fuels, are trapping additional heat in the atmosphere, causing the Earth's temperatures to rise. The average surface temperature of the planet has risen about 1.1 degrees Celsius (2.0 degrees Fahrenheit) since the late 19th century, and the past 35 years have seen a majority of the warming, with 16 of the 17 warmest years on record occurring since 2001, according to NASA.Scientists are now trying to characterize the relationship between yearly record high temperatures and human-caused global warming.In response to the past three years' record-breaking temperatures, authors of the new study calculated the likelihood of observing a three-year streak of record high temperatures since yearly global temperature records began in the late 19th century and the likelihood of seeing such a streak since 2000, when much of the warming has been observed. The study's authors determined how likely this kind of event was to happen both with and without the influence of human-caused warming.The new study considers that each year is not independent of the ones coming before and after it, in contrast to previous estimates that assumed individual years are statistically independent from each other. There are both natural and human events that make temperature changes cluster together, such as climate patterns like El Niño, the solar cycle and volcanic eruptions, according to Mann.When this dependency is taken into account, the likelihood of these three consecutive record-breaking years occurring since 1880 is about 0.03 percent in the absence of human-caused climate change. When the long-term warming trend from human-caused climate change is considered, the likelihood of 2014-2016 being the hottest consecutive years on record since 1880 rises to between 1 and 3 percent, according to the new study.The probability that this series of record-breaking years would be observed at some point since 2000 is less than 0.7 percent without the influence of human-caused climate change, but between 30 and 50 percent when the influence of human-caused climate change is considered, the new study finds.If human-caused climate change is not considered, the warming observed in 2016 would have about a 1-in-a-million chance of occurring, compared with a nearly 1-in-3 chance when anthropogenic warming is taken into account, according to the study.The results make it difficult to ignore the role human-caused climate change is having on temperatures around the world, according to Mann. Rising global temperatures are linked to more extreme weather events, such as heat waves, floods, and droughts, which can harm humans, animals, agriculture and natural resources, he said."The things that are likely to impact us most about climate change aren't the averages, they're the extremes," Mann said. "Whether it's extreme droughts, or extreme floods, or extreme heat waves, when it comes to climate change impacts ... a lot of the most impactful climate related events are extreme events. The events are being made more frequent and more extreme by human-caused climate change."The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing 60,000 members in 137 countries. Join the conversation on Facebook, Twitter, YouTube, and our other social media channels.
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Weather
| 2,017 |
August 9, 2017
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https://www.sciencedaily.com/releases/2017/08/170809073301.htm
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2016 was another warm year, report confirms
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A new report published in
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The record high global temperatures in 2015 and 2016, which saw global temperatures reach 1degC above pre-industrial levels, were the result of the long-term temperature rise attributed to greenhouse gases in combination with a temporary boost from a major El Niño event. In addition, the Arctic was exceptionally warm, particularly during 2016.Dr John Kennedy of the Met Office Hadley Centre for Climate Science and Services, lead author of the report, said, "Climatically, 2015 and 2016 saw both long-term human-induced climate change and the naturally-occurring El Niño combine to produce the two warmest years on record for global temperature. However, as the other indicators of 2016 prove, there are many more measures of the climate than global temperatures: from local extremes of temperature and rainfall to an unexpected drop in Antarctic sea ice."
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Weather
| 2,017 |
August 6, 2017
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https://www.sciencedaily.com/releases/2017/08/170806212724.htm
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By the end of the century extreme weather events may affect two in three Europeans every year
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By 2100, two in three people living in Europe may be affected by weather-related disasters, according to a study published in
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The projected increases were calculated on the assumption of there being no reduction in greenhouse gas emissions and no improvements to policies helping to reduce the impact of extreme weather events (such as medical technology, air conditioning, and thermal insulation in houses).The estimates project a rise in the death toll due to weather-related disasters in Europe -- with deaths potentially increasing by 50 times, from 3000 deaths each year between 1981-2010 to 152000 a year between 2071-2100.The number of people in Europe exposed to such events each year may also increase from one in 20 people towards the beginning of the century (25 million) to two in three people (351 million) near the end of the century.The study analyses the effects of the seven most harmful types of weather-related disaster -- heat waves, cold waves, wildfires, droughts, river and coastal floods, and windstorms -- in the 28 European countries, Switzerland, Norway and Iceland."Climate change is one of the biggest global threats to human health of the 21st century, and its peril to society will be increasingly connected to weather-driven hazards," says lead author Dr Giovanni Forzieri, European Commission Joint Research Centre, Italy. "Unless global warming is curbed as a matter of urgency and appropriate measures are taken, about 350 million Europeans could be exposed to harmful climate extremes on an annual basis by the end of the century."As part of the study, the researchers analysed 2300 disaster records from 1981-2010, which include the type of disaster, country, year and the total number of deaths caused, to estimate the population vulnerability to each of the seven weather-related disasters. They then combined this with projections of how climate change may progress and how populations might increase and migrate.The study estimates that heat waves would be the most lethal weather-related disaster, and could cause 99% of all future weather-related deaths -- increasing from 2700 deaths a year between 1981-2010 to 151500 deaths a year in 2071-2100.It also projects substantial increases in deaths from coastal flooding, which could increase from six deaths a year at the start of the century to 233 a year by the end of the century.Comparatively, wildfires, river floods, windstorms and droughts showed smaller projected increases overall, but these types of weather-related disaster could affect some countries more than others. Cold waves could decline as a result of global warming, however, the effect of this decline will not be sufficient to compensate for the other increases.Due to projected increases in heat waves and droughts, the effect is likely to be greatest in southern Europe where almost all people could be affected by a weather-related disaster each year by 2100 -- projected to cause around 700 deaths per every million people each year.Comparatively, in northern Europe one in three people could be affected by a weather-related disaster each year, resulting in three deaths per every million people each year.Climate change is likely to be the main driver behind the potential increases, accounting for 90% of the risk while population changes such as growth, migration and urbanisation account for the remaining 10%.To preserve the health and wellbeing of future generations of people in Europe, the researchers explain the need to address climate change by fulfilling the aims of the Paris Agreement to reduce climate change and increase resilience. They also note that land use and city planning -- such as reducing urban sprawl, and the need for people to use cars, and increasing the number of homes and buildings with improved air conditioning, thermal insulation and floodproofing -- will play an important role."This study contributes to the ongoing debate about the need to urgently curb climate change and minimise its consequences. The substantial projected rise in risk of weather-related hazards to human beings due to global warming, population growth, and urbanisation highlights the need for stringent climate mitigation policies and adaptation and risk reduction measures to minimise the future effect of weather-related extremes on human lives." adds Dr Forzieri.The study could help prioritise regional investments in mitigation and adaptation policies. However, the authors warn that the study has inherent levels of uncertainty due to its use of observational data and projected estimates about the scale and frequency of future weather related disasters, and the risk to populations. The study does not account for the effects of population ageing or economic growth which may alter the impact of weather-related disasters. Additionally, it assumes that hazards are independent and does not account for possible amplification of effects due to interactions between multiple weather-related disasters.
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Weather
| 2,017 |
August 3, 2017
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https://www.sciencedaily.com/releases/2017/08/170803141028.htm
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Alaska's North Slope snow-free season is lengthening
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On the North Slope of Alaska, snow is melting earlier in the spring and the snow-in date is happening later in the fall, according to a new study by CIRES and NOAA researchers. Atmospheric dynamics and sea ice conditions are behind this lengthening of the snow-free season, the scientists found, and the consequences are far reaching -- including birds laying eggs sooner and iced-over rivers flowing earlier.
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"The timing of snowmelt and length of the snow-free season significantly impacts weather, the permafrost, and wildlife -- in short, the Arctic terrestrial system as a whole," said Christopher Cox, a scientist with CIRES at the University of Colorado Boulder and NOAA's Physical Sciences Division in Boulder, Colorado. The study has been accepted for publication in the Focusing on the transition seasons on the North Slope -- the springtime snowmelt and the autumn onset of snowpack -- the researchers found that since the mid-1970s, the spring melt has been happening earlier, and the first snow has been happening later. The end result: an increase in length of the snow-free season, by about one week per decade from 1975 to 2016. From 1975 to 2016, the spring snowmelt has arrived nearly three days earlier every decade, and from 1979-2016, snow onset has arrived later, by about 4.5 days every decade.CIRES and NOAA researchers and their colleagues analyzed long-term observations of snow cover and meteorology at the NOAA Barrow Atmospheric Baseline Observatory outside of Utqiagvik (formerly Barrow), Alaska, along with other records of environmental variables in the region.Despite natural swings up and down, a persistent, long-term warming trend emerged: eight of the 10 earliest melt dates have occurred since 1990, pointing to the influence of warming Arctic temperatures. 2016 experienced the earliest melt, the latest onset of snow in autumn, and the longest snow-free season in 115 years of record-keeping -- about 45 percent longer than the average over the previous four decades.The researchers then began dissecting their data to find weather-related factors that might be contributing to these observed changes. They found different factors at work in spring versus fall. Changes in flow patterns of warm Pacific Ocean air from the south were driving earlier spring snowmelt, while decreasing summer sea ice had the greatest influence on later onset of snowpack in the fall.The researchers found that large-scale features of atmospheric circulation -- in particular, the strength and position of the Aleutian Low, a semi-permanent, subpolar area of low pressure located in the Gulf of Alaska near the Aleutian Islands -- largely determined the timing of snowmelt during spring in Alaska, by either facilitating or inhibiting the transport of warm, moist air into the region.Conversely, in autumn, the amount of open water in the Beaufort and eastern Chukchi Seas appeared to be very influential in affecting the temperature at Utqiagvik and the subsequent timing of the onset of snowpack. The extent of open water in the region during autumn has increased significantly in the past several decades, a signal other studies have linked to Arctic amplification.The rapid expansion of the North Slope's snow-free season has had consequences for water resources, wildlife behavior, the plant growing season and more, the research team reported in the new paper. For example, on Cooper Island near Utqiagvik, where a colony of black guillemots has been monitored since 1975, researchers found that the timing of the seabirds' egg laying correlates with Utqiagvik's snowmelt, so earlier melt means earlier egg laying. The timing of snowmelt also influenced the timing of peak discharge from the North Slope river system and the start of the vegetative growing season, according to the researchers."It's remarkable how rapidly things are changing in the Arctic and how the longer snow-free season affects so many other patterns -- the guillemots, vegetation growth, and fluxes of gases from the tundra," said Diane Stanitski, co-author of the paper and a scientist at the NOAA Earth System Research Laboratory in Boulder, Colorado.This spring's snowmelt date at Utqiagvik was late, on June 18, said lead author Cox. This late melt didn't make it into the paper, because analyses were done by then, but the atmospheric conditions that led to the later melt were consistent with the findings in the paper. Such variability underscores the need for continued monitoring of snow cover, Cox said.Long-term datasets from the region help scientists understand the reasons behind long-term changes and predict what the region will face in the future. "This study takes an integrated approach that addresses the need to advance Arctic environmental research at the system level, a challenge that has been recognized by the broad scientific community as necessary to improve predictions of future change," said Cox.
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Weather
| 2,017 |
August 2, 2017
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https://www.sciencedaily.com/releases/2017/08/170802152547.htm
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Deadly heat waves could hit South Asia this century
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In South Asia, a region of deep poverty where one-fifth of the world's people live, new research suggests that by the end of this century climate change could lead to summer heat waves with levels of heat and humidity that exceed what humans can survive without protection.
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There is still time to avert such severe warming if measures are implemented now to reduce the most dire consequences of global warming. However, under business-as-usual scenarios, without significant reductions in carbon emissions, the study shows these deadly heat waves could begin within as little as a few decades to strike regions of India, Pakistan, and Bangladesh, including the fertile Indus and Ganges river basins that produce much of the region's food supply.The new findings, based on detailed computer simulations using the best available global circulation models, are described this week in the journal The study follows an earlier report by Eltahir and his team that looked at projected heat waves in the Persian Gulf region. While the number of extreme-heat days projected for that region was even worse than for South Asia, Eltahir says the impact in the latter area could be vastly more severe. That's because while the Persian Gulf area has a relatively small, relatively wealthy population and little agricultural land, the areas likely to be hardest hit in northern India, Bangladesh, and southern Pakistan are home to 1.5 billion people. These areas are also among the poorest in the region, with much of the population dependent on subsistence farming that requires long hours of hard labor out in the open and unprotected from the sun."That makes them very vulnerable to these climatic changes, assuming no mitigation," says Eltahir, who spoke with MIT News from Singapore, where he is carrying out follow-up research on potential climate effects in that area.While the projections show the Persian Gulf may become the region of the worst heat waves on the planet, northern India is a close second, Eltahir says, and eastern China, also densely populated, is third. But the highest concentrations of heat in the Persian Gulf would be out over the waters of the Gulf itself, with lesser levels over inhabited land.The new analysis is based on recent research showing that hot weather's most deadly effects for humans comes from a combination of high temperature and high humidity, an index which is measured by a reading known as wet-bulb temperature. This reflects the ability of moisture to evaporate, which is the mechanism required for the human body to maintain its internal temperature through the evaporation of sweat. At a wet-bulb temperature of 35 degrees Celsius (95 degrees Fahrenheit), the human body cannot cool itself enough to survive more than a few hours.A previous study of temperature and humidity records show that in today's climate, wet-bulb temperatures have rarely exceeded about 31 C anywhere on Earth. While the earlier report from Eltahir and his colleagues showed that this survivability limit would start to be exceeded occasionally in the Persian Gulf region by the end of this century, actual readings there in the summer of 2015 showed that the 35-degree wet-bulb limit had almost been reached already, suggesting that such extremes could begin happening earlier than projected. The summer of 2015 also produced one of the deadliest heat waves in history in South Asia, killing an estimated 3,500 people in Pakistan and India.And yet, India and China remain two countries where emission rates of greenhouse gases continue to rise, driven mostly by economic growth, Eltahir says. "So I think these results pose a dilemma for countries like India. Global warming is not just a global problem -- for them, they will have some of the hottest spots" on the planet. In fact, a separate study by researchers at the University of California at Irvine and elsewhere, published recently also in Scientific Advances, reached similar conclusions based on a different kind of analysis using recent weather records.That paper was "complementary to ours, which is based on modeling," Eltahir says. The new analysis looked at results from three of the more than 20 comprehensive global climate models, which were selected because they most accurately matched actual weather data from the South Asian region. The study shows that by century's end, absent serious reductions in global emissions, the most extreme, once-in-25-years heat waves would increase from wet-bulb temperatures of about 31 C to 34.2 C. "It brings us close to the threshold" of survivability, he says, and "anything in the 30s is very severe."In today's climate, about 2 percent of the Indian population sometimes gets exposed to extremes of 32-degree wet-bulb temperatures. According to this study, by 2100 that will increase to about 70 percent of the population, and about 2 percent of the people will sometimes be exposed to the survivability limit of 35 degrees. And because the region is important agriculturally, it's not just those directly affected by the heat who will suffer, Eltahir says: "With the disruption to the agricultural production, it doesn't need to be the heat wave itself that kills people. Production will go down, so potentially everyone will suffer."But while the study provides a grim warning about what could happen, it is far from inevitable, Eltahir stresses. The study examined not just the "business as usual" case but also the effects under a moderate mitigation scenario, which showed that these dramatic, deadly effects can still be averted. "There is value in mitigation, as far as public health and reducing heat waves," he says. "With mitigation, we hope we will be able to avoid these severe projections. This is not something that is unavoidable."
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Weather
| 2,017 |
August 2, 2017
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https://www.sciencedaily.com/releases/2017/08/170802083320.htm
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Defunct satellites: Reliably determine and predict attitude motion
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Uncontrollable flying objects in the Earth's orbit are an enormous risk for active satellites and for spacecraft in general. Since April 2012, the European environmental satellite ENVISAT has also been adrift in orbit. Now, the Fraun-hofer Institute for High Frequency Physics and Radar Techniques FHR has developed pioneering methods to precisely determine the attitude rotation of malfunctioning satellites and, thus, to support de-orbiting missions in the future.
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The ENVISAT environmental satellite is one of the largest spacecraft to ever have been put into orbit by ESA. ENVISAT, which cost 2.3 billion euro and weighs nearly eight tons, was launched in 2002 and reliably monitored the Earth's climate, oceans and land surfaces until 2012 when contact was lost. The Earth-observing satellite is orbiting at an altitude of approximately 800 km -- a region of the Earth's orbit with a high density of space objects. Space junk is a major problem in low-orbit space flight. Now, ENVISAT's uncontrolled flight could potentially lead to collisions with active satellites and other space craft," Dr. Ing. Delphine Cerutti-Maori, Speaker Business Unit Space at Fraunhofer FHR, points out. "Moreover, there is further risk potential, because collisions can lead to the formation of new debris, which in turn could collide with other objects -- a dangerous snowball effect."In order to cope with this issue, ESA is currently looking for solutions to put ENVISAT into a lower orbit and to eventually let the satellite securely burn up when re-entering the Earth's atmosphere. However, these "de-orbiting missions" can only be successful if the satellite's attitude motion parameters can be determined correctly. Only then can it be determined which method is to be used to capture the satellite. The team of researchers at the Fraunhofer FHR offer support for future de-orbiting missions. "Our TIRA radar combines Ku band imaging radar and L band tracking radar. This system offers the unique possibility to image space objects at high resolutions by using ISAR techniques," Dr. Ing. Ludger Leushacke, Head of Depart¬ment Radar for Space Observation at Fraunhofer FHR explains. "In contrast to optical systems, our radar system offers decisive advantages: complete independence from weather conditions, day and night use, as well as an image resolution, which is completely independent of the distance of the object. In addition, we can determine the rotational speed of fast rotating objects, such as ENVISAT, and of slow rotating objects. "The radar raw data of ENVISAT recorded with TIRA are processed and evaluated using special methods, which were devel¬oped at Fraunhofer FHR in recent years.High-resolution radar images are generated using the relative rotation of the observed object to the stationary radar system. The object is illuminated by different aspect angles. However, the cross-range scaling in the radar image depends on the actual rotational speed, which has to be obtained from the data. "In order to address this issue, which occurs during image processing, our team of experts has developed a method that uses wire grid models of the objects to properly estimate the cross-range scaling," explains Cerutti-Maori. "For this purpose, a wire grid model is projected onto different images of a passage. The rotational vector can be reliably estimated through the temporal development of several projections during the object's passage. "To analyse the long term development of ENVISAT's motion, we were able to use observations from the period between 2011, i.e. shortly before the contact with the satellite was lost, and 2016. During its regular mission, ENVISAT was rotating slowly at about 0.06°/s, which corresponds to one revolution per Earth orbit. Shortly after the connection had been lost on April 8, 2012, it could be observed that the rotation rate had increased to almost 3°/s, or about 45 revolutions per Earth orbit. As the increase was gradual and not sudden, the researchers at Fraunhofer FHR concluded that this was not due to a collision with other objects. However, a slowing of the speed of rotation has been observed since mid-2013. At the end of 2016 it was about 1.6°/s. "Our investigations could make a significant contribution to support the future removal of the damaged ENVISAT if ESA decides to do so," says Leushacke. "The image-based reconnaissance methods developed at Fraunhofer FHR are currently unique in the world and are ideal for analysing the orientation and rotation of space objects and for predicting their long-term development in a reliable manner. In addition, they can be used to efficiently investigate a potential external damage to satellites."
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Weather
| 2,017 |
August 1, 2017
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https://www.sciencedaily.com/releases/2017/08/170801094509.htm
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Successful prediction of multi-year US droughts and wildfire risk
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The next mega-droughts and subsequent active wildfire seasons for the western U.S. might be predictable a full year in advance, extending well beyond the current seasonal forecast and helping segments of the economy related to agriculture, water management and forestry.
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The new model, developed by an international team of scientists from the U.S., South Korea and U.K., and led by Utah State University climate scientist Yoshimitsu Chikamoto, was reported in the July 26 edition of The source of this improved predictability is based on a combination of factors, including tropical climate variability, global climate change and the natural filtering effects of soils. To mitigate drought-induced socioeconomic risks, water resource managers require detailed drought forecasts as far in advance as possible. Climate prediction centers generate and routinely disseminate seasonal drought outlooks. However, predicting multi-year droughts that reach well beyond seasonal timescales is challenging for climate scientists.Over the past 15 years, parts of the western U.S. have experienced severe drought conditions and an increasing number of wildfires that take a toll on people and ecosystems. The team's research shows that in addition to contributions from natural forcings and global warming, temperature differences between the Atlantic and Pacific oceans play a role in causing drought and increasing wildfire risks. The new findings show that a warm Atlantic and a relatively cold Pacific enhance the risk for drought and wildfire in the southwestern U.S."According to our study, the Atlantic/Pacific temperature difference shows pronounced variations on timescales of more than 5 years," explained Chikamoto, USU associate professor in the department of Plants, Soils and Climate. "Like swings of a very slow pendulum, this implies that there is predictability in the large-scale atmosphere/ocean system, which we expect will have a substantial societal benefit."The new findings of successful multi-year drought/fire predictions are based on a series of computer modeling experiments, using the state-of-the-art earth system model, the most detailed data on current ocean temperature and salinity conditions, and the climate responses to natural and human-linked radiative forcing. The results of the experiments are presented in the online "We found that, even 10-months after the starting prediction, the model was tracking the observation-based soil water conditions very well," Chikamoto said. "This implies that drought and fire conditions in the next water year can be predicted from the previous winter.""This is a surprising result," said co-author Lowell Stott from the University of South California. "The atmospheric river is an important source for California water resources, but its predictability is limited to the atmospheric short memory of 2 weeks. Of course, we cannot predict an exact location, duration and timing of each drought event beyond several weeks. However, our result of multi-year drought predictability suggests that the annual frequency of atmospheric river water supply is controlled by large-scale climate variability and change. This frequency change in drought condition is much more predictable beyond several seasons.""There are three predictable processes," explained co-author Axel Timmermann, director of the Institute for Basic Science Center for Climate Physics, Pusan National University in South Korea. "At first, tropical ocean temperature contrast between Pacific and Atlantic causes slow climate variability due to its large thermodynamical inertia, and then affects the atmospheric high-pressure ridge off the California coast via global teleconnections. Secondly, the slow variation in this high-pressure ridge is enhanced by filtering out the atmospheric noise through land soil processes. Thirdly, global climate change contributes to the long-term drying trend in the West. A combination of these three processes explains the recent southwestern U.S. drought event for 2011-2014."The application of this findings is anticipated to be in great demand. "Our study clearly demonstrates a new possibility of international, ongoing, decadal forecasting activities, said co-author Magdalena Balmaseda from the European Centre for Medium-Range Weather Forecasts. "We anticipate that multi-year drought predictions will be available soon by collaborating with operational forecast centers."
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Weather
| 2,017 |
July 31, 2017
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https://www.sciencedaily.com/releases/2017/07/170731134126.htm
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Coral disease outbreaks fluctuate with El Niño years, new research finds
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Occurrences of three common diseases affecting Caribbean corals spike during El Niño years, an alarming association given how climate change may boost the intensity of El Niños.
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The findings from Florida Institute of Technology research associate Carly Randall and biology professor Rob van Woesik, published earlier this month in the journal "We found that three coral diseases -- white-band disease, yellow-band disease and dark-spot syndrome -- peak every 2-4 years, and that they share common periodicities with El Niño cycles," Randall said. "Our results indicate that coral diseases cycle predictably and that they often correspond with El Niño."And because of the potential increase in the intensity of El Niño weather patterns associated with climate change, "our findings suggest that we might see diseases in corals ramping up in the coming decades," Randall added.Because disease outbreaks in corals have followed El Niño-fueled coral bleaching events in the past, there was speculation about the connection between the diseases and the El Niño cycles, which are associated with warmer than usual weather in the Caribbean. This study, titled "Some coral diseases track climate oscillations in the Caribbean," confirms the speculation.Such climate-driven patterns in the ocean are similar to patterns described for malaria and dengue fever on the land, which are reported to track climate cycles.
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Weather
| 2,017 |
July 27, 2017
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https://www.sciencedaily.com/releases/2017/07/170727102928.htm
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Model developed to predict, prevent power outages using big data
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High-speed winds during a thunderstorm may cause trees around an electric grid to crash into the distribution system feeders causing an outage in that area. Currently, most utility companies diminish such accidents by scheduling regular tree-trimming operations. This effort is costly and is based on a rotational approach to different service areas, which may take months and sometimes years before all trees are trimmed.
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Texas A&M University researchers have developed an intelligent model that can predict a potential vulnerability to utility assets and present a map of where and when a possible outage may occur. The predictive feature allows the trees in the most critical areas with the highest risk to be trimmed first.Dr. Mladen Kezunovic, Regents Professor and holder of the Eugene E. Webb professorship in the Department of Electrical and Computer Engineering, along with graduate students Tatjana Dokic and Po-Chen Chen, have developed the framework for a model that can predict weather hazards, vulnerability of electric grids and the economic impact of the potential damage.By analyzing the impact of a potential vulnerability and weather impacts on power system outages, the researchers can predict where and when outages can occur. Predicting an optimal tree trimming schedule that would minimize the risk of vegetation-related outages is only one of the applications."The utility grids and related assets are mostly located outdoors and are exposed to all kinds of weather hazards. Dealing with aging infrastructure assets adds another layer of complexity that utility companies face," said Kezunovic. "Any kind of environmental data that has some relevance to the power system can be fed into this prediction framework."Data such as a utility company's operational records, weather forecasts, altitude and vegetation around the power systems can be used to customize the applications of the model.The model is flexible and can process a variety of data despite differing formats and data sources. The researchers say processing such data is a demanding task they have been able to solve. Every source of data and its presentation is different and multifaceted. Based on the goals, they select a large amount of input data from several sources and perform a risk analysis.Such comprehensive data analytics makes the power system and its operations more reliable."The first and foremost goal of utility companies is to assure uninterrupted service," said Chen. "By improving reliability, we can predict outages. If we can prevent outages with historical and close-to-real-time data, we can save millions of dollars since the outages may be mitigated."The researchers describe their methodology for the framework as a three-part process. First, they investigate the probability of a potential hazard, such as severe weather. Next, they assess the vulnerability of the utility assets by taking the weather probability and predicting its impact on the assets. The last and most significant step is evaluating the impact of certain events and the calculation of costs of reliability indices and maintenance, replacement and repair.The model analyzed historical and close-to-real-time weather data and successfully predicted future vulnerabilities enabling utility companies to have efficient mitigation measures, such as inspection, repair and maintenance processes."Overall the risk analysis helps predict the probability of events happening in the near future and then adds the financial impact allowing development of an optimal action plan for the utility operators to execute," said Chen."When outages happen, utility companies lose millions of dollars in just repairs," said Dokic. "The past has shown how certain outages have cost precious lives too."The researchers used CenterPoint Energy's utility data in their framework and have presented a proof of concept to the company. Their next step is implementation of the model on CenterPoint's database and environment.Kezunovic is also director of the Texas A&M Engineering Experiment Station's Smart Grid Center. The research was supported by CenterPoint Energy, the National Science Foundation (NSF) Center for Ultra-Wide Area Resilient Electric Energy Transmission Networks and in part by NSF Power Systems Engineering Research Center and NSF Smart Grid Big Data Spoke grants. Read more about the research in the
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Weather
| 2,017 |
July 26, 2017
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https://www.sciencedaily.com/releases/2017/07/170726102952.htm
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Atlantic/Pacific ocean temperature difference fuels US wildfires
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An international team of climate researchers from the US, South Korea and the UK has developed a new wildfire and drought prediction model for southwestern North America. Extending far beyond the current seasonal forecast, this study published in the journal
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Over the past 15 years, California and neighboring regions have experienced heightened drought conditions and an increase in wildfire numbers with considerable impacts on human livelihoods, agriculture, and terrestrial ecosystems. This new research shows that in addition to a discernible contribution from natural forcings and human-induced global warming, the large-scale difference between Atlantic and Pacific ocean temperatures plays a fundamental role in causing droughts, and enhancing wildfire risks."Our results document that a combination of processes is at work. Through an ensemble modeling approach, we were able to show that without anthropogenic effects, the droughts in the southwestern United States would have been less severe," says co-author Axel Timmermann, Director of the newly founded IBS Center for Climate Physics, within the Institute for Basics Science (IBS), and Distinguished Professor at Pusan National University in South Korea. "By prescribing the effects of human-made climate change and observed global ocean temperatures, our model can reproduce the observed shifts in weather patterns and wildfire occurrences."The new findings show that a warm Atlantic and a relatively cold Pacific enhance the risk for drought and wildfire in the southwestern US. "According to our study, the Atlantic/Pacific temperature difference shows pronounced variations on timescales of more than 5 years. Like swings of a very slow pendulum, this implies that there is predictability in the large-scale atmosphere/ocean system, which we expect will have a substantial societal benefit," explains Yoshimitsu Chikamoto, lead author of the study and Assistant Professor at the University of Utah in Logan.The new drought and wildfire predictability system developed by the authors expands beyond the typical timescale of seasonal climate forecast models, used for instance in El Niño predictions. It was tested with a 10-23 month forecasting time for wildfire and 10-45 for drought. "Of course, we cannot predict individual rainstorms in California and their local impacts months or seasons ahead, but we can use our climate computer model to determine whether on average the next year will have drier or wetter soils or more or less wildfires. Our yearly forecasts are far better than chance," states Lowell Stott, co-author of the study from the University of Southern California in Los Angeles.Bringing together observed and simulated measurements on ocean temperatures, atmospheric pressure, water soil and wildfire occurrences, the researchers have a powerful tool in their hands, which they are willing to test in other regions of the world: "Using the same climate model configuration, we will also study the soil water and fire risk predictability in other parts of our world, such as the Mediterranean, Australia or parts of Asia," concludes Timmermann. "Our team is looking forward to developing new applications with stakeholder groups that can benefit from better soil water forecasts or assessments in future fire risk."
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Weather
| 2,017 |
July 26, 2017
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https://www.sciencedaily.com/releases/2017/07/170726091513.htm
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Trees can make or break city weather
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Even a single urban tree can help moderate wind speeds and keep pedestrians comfortable as they walk down the street, according to a new University of British Columbia study that also found losing a single tree can increase wind pressure on nearby buildings and drive up heating costs.
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The researchers used remote-sensing laser technology to create a highly detailed computer model of a Vancouver neighbourhood down to every tree, plant and building. They then used computer simulation to determine how different scenarios -- no trees, bare trees, and trees in full leaf -- affect airflow and heat patterns around individual streets and houses."We found that removing all trees can increase wind speed by a factor of two, which would make a noticeable difference to someone walking down the street. For example, a 15 km/h wind speed is pleasant, whereas walking in 30 km/h wind is more challenging," said lead author Marco Giometto, who wrote the paper as a postdoctoral fellow in civil engineering at UBC.Trees also moderated the impact of wind pressure on buildings, particularly when it goes through small gaps in and between buildings."Wind pressure is responsible for as much as a third of a building's energy consumption. Using our model, we found that removing all the trees around buildings drove up the building's energy consumption by as much as 10 per cent in winter and 15 per cent in summer," said Giometto.The researchers compared the simulated scenarios against a decade of measured wind data from a 30-metre-tall research tower operated by UBC in the same Vancouver neighbourhood. They discovered that even bare trees in the winter months can moderate airflow and wind pressure, contributing to a more comfortable environment."Even bare branches play a role. Deciduous trees, which shed their leaves every year, reduce pressure loading on buildings throughout the year-it's not only evergreens that are important in the city," said Marc Parlange, who supervised the work while a professor of civil engineering at UBC.The model, piloted last year, is the first to simulate a real urban neighbourhood in extreme detail, added study co-author and UBC geography professor Andreas Christen."Information from such models can improve weather forecasts in order to predict the effects of a storm on a building and pedestrian level," said Christen. "It could also help city planners in designing buildings, streets, and city blocks to maximize people's comfort and limit wind speed to reduce energy loss."
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Weather
| 2,017 |
July 24, 2017
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https://www.sciencedaily.com/releases/2017/07/170724105044.htm
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Could 'cocktail geoengineering' save the climate?
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Geoengineering is a catch-all term that refers to various theoretical ideas for altering Earth's energy balance to combat climate change. New research from an international team of atmospheric scientists published by
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Carbon dioxide emissions from the burning of coal, oil, and gas not only cause Earth to get hotter, they also affect weather patterns around the world. Management approaches need to address both warming and changes in the amount of rainfall and other forms of precipitation.So-called solar geoengineering aims to cool the planet by deflecting some of the Sun's incoming rays. Ideas for accomplishing this include the dispersion of light-scattering particles in the upper atmosphere, which would mimic the cooling effect of major volcanic eruptions.However, climate-modeling studies have shown that while this scattering of sunlight should reduce the warming caused by greenhouse gases in the atmosphere, it would tend to reduce rainfall and other types of precipitation less than would be optimal.Another approach involves thinning of high cirrus clouds, which are involved in regulating the amount of heat that escapes from the planet to outer space. This would also reduce warming, but would not correct the increase in precipitation caused by global warming.One method reduces rain too much. Another method reduces rain too little.This is where the theoretical cocktail shaker gets deployed.The team -- which includes Carnegie's Ken Caldeira, Long Cao and Lei Duan of Zhejiang University, and Govindasamy Bala of the Indian Institute of Science -- used models to simulate what would happen if sunlight were scattered by particles at the same time as the cirrus clouds were thinned. They wanted to understand how effective this combined set of tools would be at reversing climate change, both globally and regionally."As far as I know, this is the first study to try to model using two different geoengineering approaches simultaneously to try to improve the overall fit of the technology," Caldeira explained.The good news is that their simulations showed that if both methods are deployed in concert, it would decrease warming to pre-industrial levels, as desired, and on a global level rainfall would also stay at pre-industrial levels. But the bad news is that while global average climate was largely restored, substantial differences remained locally, with some areas getting much wetter and other areas getting much drier."The same amount of rain fell around the globe in our models, but it fell in different places, which could create a big mismatch between what our economic infrastructure expects and what it will get," Caldeira added. "More complicated geoengineering solutions would likely do a bit better, but the best solution is simply to stop adding greenhouse gases to the atmosphere."Caldeira said that the international collaboration of scientists (including scientists from China and India) undertook this research as part of a broader effort aimed at understanding the effectiveness and unintended consequences of proposed strategies for reducing climate change and its impacts.
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Weather
| 2,017 |
July 24, 2017
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https://www.sciencedaily.com/releases/2017/07/170724083034.htm
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'Hindcasting' study investigates the extreme 2013 Colorado flood
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In September 2013, severe storms struck Colorado with prolonged, heavy rainfall, resulting in at least nine deaths, 1,800 evacuations and 900 homes destroyed or damaged. The eight-day storm dumped more than 17 inches of rain, causing the Platte River to reach flood levels higher than ever recorded.
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The severity of the storms, which also occurred unusually late in the year, attracted the interest of scientists at Lawrence Berkeley National Laboratory who specialize in studying extreme weather. In many instances, their research has shown that such events are made more intense in a warmer climate.In a paper that appeared online on July 18, 2017 at "The storm was so strong, so intense, that the standard climate models that do not resolve fine-scale details were unable to characterize the severe precipitation or large scale meteorological pattern associated with the storm," said Michael Wehner, a climate scientist in the lab's Computational Research Division and co-author of the paper.The researchers then turned to a different framework using the Weather Research and Forecasting regional model to study the event in more detail. The group used the publicly available model, which can be used to forecast future weather, to "hindcast" the conditions that led to the Sept. 9-16, 2013 flooding around Boulder, Colorado. The model allowed them to study the problem in greater detail, breaking the area into 12-kilometer squares.They ran 101 hindcasts of two versions of the model: one based on realistic current conditions that takes human-induced changes to the atmosphere and the associated climate change into account, and one that removed the portion of observed climate change attributed to human activities. The difference between the results were then attributed to these human activities. The human influence was found to have increased the magnitude of heavy rainfall by 30 percent. The authors found that this increase resulted in part from the ability of a warmer atmosphere to hold more water."This event was typical in terms of how the storm sent water to the area, but it was unusual in terms of the amount of water and the timing," said co-author Dáithí Stone, also of Berkeley Lab. "We know that the amount of water air can hold increases by about 6 percent per degree Celsius increase, which led us to expect that rainfall would have been 9-15 percent higher, but instead we found it was 30 percent higher."The results perplexed the team initially as the answers were turning out to be more complicated than they originally postulated -- the storm was more violent in terms of both wind and rain."We had expected the moist air hitting the mountain range to be 'pushing' water out of the air," said lead author Pardeep Pall. "What we had not realized was that the rain itself would also be 'pulling' more air in. Air rises as it is raining, and that in turn pulled in more air from below, which was wet, producing more rain, causing more air to raise, pulling in more air, and so on."The greater rainfall in turn led to more flooding and more damage. Photos from the storm showed many cars wrecked or stranded as roads and bridges were washed away. Damage to roadways alone was estimated at $100-150 million."The increase in precipitation was greater than the warming alone would have predicted," Stone said. "Using the local dynamical model, we found that the "storm that was" was more violent than the "storm that might have been," something we hadn't hypothesized."Christina Patricola, co-author and research scientist in the lab's Climate and Ecosystem Sciences Division, who was working at Texas A&M when during the study, said understanding extreme weather is important because the way we experience climate, for instance through weather-related damage, tends to be dominated by extreme weather. However, the nature of such events is also hard to understand because they are so rare. Event attribution studies like the one described in the paper can help lead to improved understanding.The authors emphasized that the study is not intended to predict such events in the future."This was a very rare event and remains so, and we're not making predictions with this work," Stone said. "The exact event won't happen again, but if we get the same sort of weather pattern in a climate that is even warmer than today's, then we can expect it to dump even more rain." But beyond the increased amount of precipitation, Wehner adds, "this study more generally increases our understanding of how the various processes in extreme storms can change as the overall climate warms." Despite the understanding gained through this study, many questions about extreme weather events remain."Our climate modeling framework opens the door to understanding other types of extreme weather events," said Patricola. "We are now investigating how humans may have influenced tropical cyclones. Advances in supercomputing make it feasible to run simulations that can reveal what is happening inside storm clouds."The models were run as part of the Calibrated and Systematic Characterization, Attribution, and Detection of Extremes (CASCADE) project at Berkeley Lab. The models were run on supercomputers at the National Energy Research Scientific Computing (NERSC) Center, a DOE Office of Science User Facility located at Berkeley Lab.
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Weather
| 2,017 |
July 20, 2017
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https://www.sciencedaily.com/releases/2017/07/170720193219.htm
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North American monsoon storms fewer but more extreme
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Monsoon season now brings more extreme wind and rain to central and southwestern Arizona than in the past, according to new research led by the University of Arizona.
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Although there are now fewer storms, the largest monsoon thunderstorms bring heavier rain and stronger winds than did the monsoon storms of 60 years ago, the scientists report."The monsoon is the main severe weather threat in Arizona. Dust storms, wind, flash flooding, microbursts -- those are the things that are immediate dangers to life and property," said co-author Christopher Castro, a UA associate professor of hydrology and atmospheric sciences.The researchers compared precipitation records from 1950-1970 to those from 1991-2010 for Arizona. The researchers also used those records to verify that their climate model generated realistic results."This is one of the first studies to look at long-term changes in monsoon precipitation," Castro said. "We documented that the increases in extreme precipitation are geographically focused south and west of the Mogollon Rim -- and that includes Phoenix."The region of Arizona with more extreme storms includes Bullhead City, Kingman, the Phoenix metropolitan area, the Colorado River valley and Arizona's low deserts, including the towns of Casa Grande, Gila Bend, Ajo, Lukeville and Yuma.The Tohono O'odham Reservation, Luke Air Force Base, the Barry Goldwater Air Force Range and the Yuma Proving Ground are also in the region with more extreme monsoon weather.Tucson is just outside of the zone with more extreme storms.Having less frequent but more intense storms is consistent with what is expected throughout the world due to climate change, Castro said."Our work shows that it certainly holds true for the monsoon in Arizona," he said.When the researchers compared the results from climate and weather models to the actual observations, the model with a resolution of less than 1.5 miles (2.5 km) accurately reproduced the precipitation data. The models with resolutions of 10 miles or more did not."You just can't trust coarser simulations to represent changes in severe weather. You have to use the high-resolution model," Castro said.First author Thang M. Luong conducted the research as part of his doctoral work at the UA. He is now a postdoctoral researcher at King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.The paper, "The More Extreme Nature of North American Monsoon Precipitation in the Southwestern U.S. as Revealed by a Historical Climatology of Simulated Severe Weather Events," by Luong, Castro, Hsin-I Chang and Timothy Lahmers of the UA Department of Hydrology and Atmospheric Sciences and David K. Adams and Carlos A. Ochoa-Moya of the Universidad Nacional Autónoma de México, México D.F. was published July 3 in the early online edition of the The U.S. Department of Defense Strategic Environmental Research and Development Program and the Universidad Nacional Autónoma de México PAPIIT funded the research.The researchers wanted to identify risks from warm-season extreme weather, especially those to Department of Defense installations in the American Southwest.Existing global and regional climate change models don't represent the North American monsoon well in either seasonal forecasts or climate projections, the research team wrote.Looking at the average precipitation over the entire monsoon season doesn't show whether monsoon storms are becoming more severe now compared with 60 years ago, Castro said.Therefore Luong, Castro and their colleagues looked for extreme rainfall events during 1950-1970 as compared with 1991-2010. Average precipitation was about the same, but 1991-2011 had more storms with very heavy rain."What's going on in the changes to the extremes is very different from what goes on in the changes to the mean," Castro said. "Big storms, heavy flooding -- we found out those types of extreme precipitation events are becoming more intense and are becoming more intense downwind of the mountain ranges."The team tested a common computer model of the atmosphere to try to replicate the historical changes in monsoon storm intensity. The model, similar to one used by the National Weather Service for forecasts, produces results similar to what would be observed on radar or satellite imagery by realistically simulating the physical structure of monsoon thunderstorms.A key innovation of the UA research was the level of detail -- the team tested several different levels of resolution. Only by using the high resolution of 1.5 miles (2.5 km) could the model replicate the actual rainfall recorded for the two 20-year periods being compared.The recorded data showed only rainfall. The high-resolution models indicated rainier monsoon storms were accompanied by higher winds and more downbursts."Because the models get the precipitation right, it gives us confidence that the models get the winds right too," Castro said.He said that in Phoenix, monsoon storms used to be late in the evening but are now happening earlier.The time shift makes the storms more dangerous, he said. "It's when people are more likely to be out on the roads."The team's next step, Castro said, is investigating whether the North American Monsoon is changing in Mexico.
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Weather
| 2,017 |
July 20, 2017
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https://www.sciencedaily.com/releases/2017/07/170720155320.htm
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Sunny, rainy, or cloudy: New study shows how weather impacts response to mobile ads
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Among the many factors that impact digital marketing and online advertising strategy, a new study in the INFORMS journal
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As mobile users may have already noticed, many major brands -- including Burberry, Ace Hardware, Taco Bell, Delta Airlines, and Farmers Insurance -- are currently leveraging weather-based promotions. Indeed, more than 200 others have partnered with the Weather Channel Company for targeted advertising and promotions.The study, "Sunny, Rainy, and Cloudy with a Chance of Mobile Promotion Effectiveness," was conducted by Chenxi Li of Beihang University, Xueming Luo of Temple University, Cheng Zhang of Fudan University, and Xiaoyi Wang of Zhejiang University. The authors examined field experiment datasets with mobile platforms (SMS and APP) on two digital products (video-streaming and e-book reading) on over six million mobile users in 344 cities across China. They simultaneously tracked weather conditions at both daily and hourly rates across these cities, with a focus on sunny, cloudy and rainy weather.The authors found that overall, consumer response to mobile promotions was 1.2 times higher and occurred 73 percent faster in sunny weather than in cloudy weather. However, during raining conditions, that response was .9 times lower and 59 percent slower than during cloudy weather. Better-than-yesterday weather and better-than-forecast weather engender more purchase responses. A good deviation from the expected rainy or cloudy weather with relatively rare events of sunshine significantly boosts purchase responses to mobile promotions. In addition, compared with a neutral tone, the negative tone of prevention ad content hurts the initial promotion boost induced by sunshine, but improves the initial promotion drop induced by rainfall. The authors also ruled out the possibility that the results could arise purely because of different mobile usage behaviors during different weather conditions. Their results also took into account the effects of individual locations, temperature, humidity, visibility, air pressure, dew point, wind, and time of day."Obviously, although brand managers cannot control the mother-nature weather, our findings are non-trivial because they suggest that brands can leverage the relevant, local weather information in mobile promotions. Firms should use the prevention-tone ad copy on rainy days and the simple neutral-tone ad copy on sunny days to attain greater bang for the buck," said Li."Given that consumers nowadays are inundated with and annoyed by irrelevant ads on their personal mobile devices and small screens, for marketers, these findings imply new opportunities of customer data analytics for more effective weather-based mobile targeting," Luo added.
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Weather
| 2,017 |
July 20, 2017
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https://www.sciencedaily.com/releases/2017/07/170720100513.htm
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Hot dogs: Is climate change impacting populations of African wild dogs?
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Climate change may be harming the future of African wild dogs (Lycaon pictus) by impacting the survival rates of pups, according to one of the first studies on how shifting temperatures are impacting tropical species.
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Led by scientists from ZSL (Zoological Society of London) and published in the Three concurrent studies, undertaken by ZSL, the Botswana Predator Conservation Trust, and the African Wildlife Conservation Fund, monitored a total of 73 wild dog packs at sites in Kenya, Botswana and Zimbabwe, over a combined 42 years of study.Tracking with high-tech collars showed that wild dog packs spent less time hunting on hot days. When packs tried to raise pups in hot weather, more of the pups died, potentially because they received less food from individuals returning from hunts.At the Botswana site, temperatures increased steadily over 24 years of monitoring. The average daily maximum temperature during the pup-rearing period was roughly 1°C higher in the first 12 years of monitoring than in the second 12 years, and over the same period the average number of pups surviving per pack per year fell from five to three.The study's lead author, Professor Rosie Woodroffe of ZSL's Institute of Zoology, said: "Our study shows the truly global impact of climate change. When most people think about wildlife in a changing climate, they think of polar bears clinging to melting ice, but even species who have adapted to tropical weather are being impacted by the changes to their environment."Worryingly, this new threat may be affecting wild dogs deep inside wildlife areas where we would expect them to be protected from human impacts. With habitat fragmented and destroyed in cooler areas, wild dogs have literally nowhere to go. Sadly, climate change may bring extinction a step closer for this amazing species."Now our team at ZSL is focused on identifying conservation actions which might reduce these climate impacts on wild dogs, and working out where they are most needed."African wild dogs are one of the world's most endangered carnivores and their populations are in decline, with estimates suggesting that fewer than 700 packs currently remain in the wild.Although considered one of the most successful predators on Earth due to the high kill-rate their cooperative hunting achieves, African wild dog populations are declining due to pressures including habitat loss and human-wildlife conflict.Building on this study's findings, ZSL is conducting further research to explore whether and how climate change impacts on wild dogs might be mitigated. Find out more about ZSL's conservation efforts for African wild dogs at
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Weather
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July 17, 2017
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https://www.sciencedaily.com/releases/2017/07/170717115343.htm
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Unbalanced wind farm planning exacerbates fluctuations
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The expansion of renewable energy has been widely criticised for increasing weather-dependent fluctuations in European electricity generation. A new study shows that this is due less to the variability of weather than from a failure to consider the large-scale weather conditions across the whole continent: many European countries are unilaterally following national strategies to expand wind energy capacities without looking beyond their own backyard.
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It would be better, however, for individual countries to work together and to promote the expansion of wind capacity in other European regions that are currently making very little use of wind power. Balancing capacity across the continent would effectively minimise the extreme fluctuations caused by the varied weather conditions that currently affect wind speeds. This is the conclusion reached by a group of weather and energy researchers from ETH Zürich and Imperial College London in a new study, which has just been published in the journal The researchers conducted their study by combining Europe-wide data on large-scale weather conditions from the past 30 years with wind and solar electricity production data. This made use of the Renewables.ninja platform developed at ETH Zürich for simulating the output of Europe's wind and solar farms based on historical weather data. This open simulation tool is available for anyone to use worldwide, as part of the effort to improve transparency and openness of science.The researchers used this data to model how wind power is related to seven prevailing "weather regimes" in Europe and how it will change with the further expansion of wind energy capacity. These weather regimes explain why European wind electricity generation suffers from fluctuations lasting several days.Some regimes are characterised by cyclones rolling in from the Atlantic bringing high winds to western Europe, but these are accompanied by concurrent calm conditions in the east. Other regimes see calmer weather from the Atlantic. But at the same time, wind speeds consistently increase in southern Europe and northern Scandinavia."There is hardly a weather situation in which there is no wind across the entire continent and thus all of Europe would lack wind power potential" explain Christian Grams, lead author of the study from the Institute for Atmospheric and Climate Science at ETH Zurich.However, today's wind farms are distributed irregularly across Europe, mostly in countries bordering the North Sea. This results in uneven wind electricity generation, because most capacity is installed in neighbouring countries with similar weather conditions. This means that if a stable high-pressure system causes a lull for a few days or even weeks over the North Sea, as happened in the winter of 2016/17, Europe-wide wind electricity generation drops dramatically.The problem for Europe's power system will be exacerbated by countries following their own national strategies for expanding wind power, which will further concentrate capacity in the North Sea region. This will lead to even more extreme fluctuations: the difference between high production in favourable wind conditions and low production during a lull could be as much as 100 gigawatts -- roughly the same capacity as 100 nuclear power plants -- and would have to be made available or held back within the course of only a few days.If European countries were to cooperate and set up future wind farms based on understanding of the continent-scale weather regimes, fluctuations in future wind energy could be stabilised at the current level of around 20 gigawatts. The Balkans, Greece, the western Mediterranean, and northern Scandinavia are all potential sites.These locations would all have enough wind if, for example, high pressure led to a lull in the North Sea. Likewise, if a stable high-pressure area slowed wind production in the Mediterranean, the wind farms around the North Sea would produce enough electricity. "This is why wind capacity in countries such as Greece or Bulgaria could act as a valuable counterbalance to Europe's current wind farms. However, this would require a paradigm shift in the planning strategies of countries with wind power potential," emphasises co-author Iain Staffell from Imperial College London.The authors say that it would be difficult to store electricity for several days to balance these multi-day fluctuations -- with batteries or pumped-storage lakes in the Alps, for example -- since the necessary amount of storage capacity will not be available in the foreseeable future. Current storage technologies are more suited to compensating for shorter fluctuations of a few hours or days.Moreover, a wider geographical distribution of wind farms also requires the expansion of the transmission grid. However, such a pan-European renewable energy system could still provide Switzerland with the opportunity to use its hydropower capacities more economically in order to compensate for short-term fluctuations.Using solar energy to compensate for gaps over several days would only work on a regional level at best. The researchers say that in order to compensate for fluctuations across Europe, solar energy capacity would have to be increased tenfold."The sun often shines when it's calm," explains co-author Stefan Pfenninger, from the Institute for Environmental Decisions at ETH Zürich, "but in winter, there is often not enough sunshine in central and northern Europe to produce sufficient electricity using solar panels." It would therefore make little sense to compensate for fluctuations in wind energy with a massive expansion of solar capacity.The researchers now hope that energy producers and network operators, as well as governments and politicians, will hear about these new findings and better coordinate Europe-wide planning and grid expansion.
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Weather
| 2,017 |
July 14, 2017
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https://www.sciencedaily.com/releases/2017/07/170714140454.htm
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Climate change: Biodiversity rescues biodiversity in a warmer world
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The last month was recorded as the warmest June ever in many parts of the world. Last year, 2016, was the warmest year in the modern temperature record. Our planet is constantly heating up. This poses direct threats to humans, like extreme weather events and global sea-level rise, but scientists are concerned that it may also affect our well-being indirectly via changes in biodiversity. The variety of life, from plants and animals to microorganisms, is the basis of many services ecosystems provide to us, for example clean drinking water or food. Today, ecologists are challenged by the question: what does a warmer world mean for biodiversity? More species, less species, or no change?
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A team of ecologists from the German Centre for Integrative Biodiversity Research (iDiv), Leipzig University, and the University of Minnesota found that climate warming can both increase and decrease biodiversity, and that the direction of the effect depends on how much biodiversity there is in the first place. In a long-running field experiment in Cedar Creek, Minnesota, the researchers established more than 30 different meadow plots, some with only one plant species (monocultures), and others with up to 16 different plant species. Then, they warmed the meadows with heating lamps to approximately 3°C above the ambient temperature. Subsequently, the researchers recorded how this affected nematodes, little worms that live in the soil in high abundance and of which many different species exist. Nematodes play important roles for several ecosystem functions, for example they help to make the soil fertile which is crucial for plant production.When the researchers warmed the monoculture plots, the diversity of nematodes substantially declined. However, when they warmed the plots with a high number of different plant species, the number of nematode species increased. Dr Madhav P. Thakur, the lead author of the study and a postdoctoral researcher at the iDiv research centre and the Leipzig University, says: "The story is simple; you need biodiversity to conserve biodiversity in a warmer world."That's not, however, the end of the story. The researchers also report the limitation of biodiversity in rescuing biodiversity in a warmer world. While they did find a greater number of nematode species in the warmed plots with high plant diversity, those nematode species were also more closely related, or in other words, more similar, to each other. "The reason was that these species had all been selected for a common characteristic, namely tolerance to a warmer environment," Thakur explains. This increase in similarity can have implications for how well biological communities can respond to future environmental changes, potentially limiting the "insurance" effect inherent in a higher numbers of species," says Dr Jane Cowles, a co-author and postdoctoral researcher at the University of Minnesota. What will be the consequences for the stability of our planet's ecosystems? The authors encourage future research to solve this puzzle.The monoculture meadow created for the experiment resembled meadows found in intensively managed agricultural land. These new research findings therefore support conservationists who are advocating for maintaining species-rich ecosystems and farmland to sustain biodiversity, and thus human well-being, in a warmer world. This may help to prevent negative effects of climate warming, although likely with some limitations.
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Weather
| 2,017 |
July 11, 2017
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https://www.sciencedaily.com/releases/2017/07/170711121504.htm
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Warm winter events in Arctic becoming more frequent, lasting longer
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Arctic winter warming events -- winter days where temperatures peak above 14 degrees Fahrenheit (minus 10 degrees Celsius) -- are a normal part of the climate over the ice-covered Arctic Ocean, but new research by an international team that includes NASA scientists finds these events are becoming more frequent and lasting longer than they did three decades ago.
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Because fall and winter is when Arctic sea ice grows and thickens, warmer winter air temperatures will further impede ice growth and expansion, accelerating the effects of global warming in the Arctic.A new study, published in The researchers arrived at the results by gathering and analyzing data from field campaigns, drifting weather stations and buoys across the Arctic Ocean from 1893 to 2017, as well as the ERA-Interim record, a global atmospheric reanalysis provided by the European Centre for Medium-Range Weather Forecasts in Reading, UK, from 1979 to 2016.The findings build on other recent evidence of Arctic winter warming. The winter of 2015-2016, for example, saw temperatures nearly 3.6 degrees Fahrenheit (2 degrees Celsius) warmer than the previous record high monthly winter temperature. At the end of December 2015, scientists recorded a temperature of 36 degrees Fahrenheit (2.2 degrees Celsius) in the Central Arctic, the warmest temperature ever recorded in this region from December through March.In the most recent years of the study, each warming event was associated with a major storm entering the region. During these storms, strong winds from the south blow warm, moist air from the Atlantic into the Arctic."The warming events and storms are in effect one and the same," said Robert Graham, a climate scientist at the Norwegian Polar Institute in Tromsø, Norway, and lead author of the new study. "The more storms we have, the more warming events, the more days with temperatures less than minus 10 degrees Celsius (14 degrees Fahrenheit) rather than below minus 30 degrees Celsius (minus 22 degrees Fahrenheit), and the warmer the mean winter temperature is."Storms that bring warm air to the Arctic not only prevent new ice from forming, but can also break up ice cover that is already present, Graham said. He added that the snowfall from storms also insulates current ice from the cold atmosphere that returns to the Arctic after the cyclones, which can further reduce ice growth.Two of the study's authors, Alek Petty and Linette Boisvert of NASA's Goddard Space Flight Center in Greenbelt, Maryland, previously researched one such storm that took place in the Arctic during the winter of 2015-2016."That particular cyclone, which lasted several days and raised temperatures in the region close to the melting point, hindered sea ice growth while its associated strong winds pushed the sea ice edge back, leading to a record low spring sea ice pack in 2016," said Petty and Boisvert. "This new study provides the long-term context we were missing, using direct observations going back the end of the 19th century. It shows that these warm events have occurred in the past, but they were not as long-lasting or frequent as we're seeing now. That, combined with the weakened sea ice pack, means that winter storms in the Arctic are having a larger impact on the Arctic climate system."Yet the frequency and duration of these warming events varies by region. On average, the Atlantic side of the North Pole now has ten warming events each winter, while the Pacific Central Arctic has five such events, according to the study. More storms come in to the Arctic from the Atlantic Ocean during winter, which results in more warming events on the Atlantic side of the North Pole.The next step for Graham and his colleagues is to understand what is fueling the increase of these storms and how they might change. Recent research shows that reduced ice cover and shifting weather patterns due to climate change may increase storms' frequency and impact, Graham said."It is difficult to say how much this pattern will amplify in the future," he said.
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Weather
| 2,017 |
July 11, 2017
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https://www.sciencedaily.com/releases/2017/07/170711085519.htm
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Does the European public understand the impacts of climate change on the ocean?
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The oceans are our lifeline and the lungs of our planet producing 70% of the oxygen we breathe. They regulate our climate and provide us with food, new medicines, and energy. However, the ocean -- and therefore the future of humanity -- is threatened by climate change. But how much does the public really understand the impacts of climate change and what can be done to facilitate better communication between scientists, the media, government, NGOs, and the public?
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An opinion poll of 10,000 citizens published in 54% of European citizens believe that humans play only a partial role or no role in climate change. Many who thought that they were well informed on the impacts of climate change on the ocean believe scenarios that may happen by 2100 if we do not reduce greenhouse gas emissions have already occurred e.g. loss of Arctic sea-ice in the summer (26% of respondents) and sea temperature increases of more than 2°C (30% of respondents). "This is hugely disturbing because if these changes have already occurred in their minds, what incentive do these citizens have to demand action to prevent such changes?" says Duarte.The European public perceive ocean pollution as the most severe human impact on the ocean, however they are not well informed on ocean acidification caused by carbon dioxide emissions. Melting sea ice, coastal flooding, sea level rise, and extreme weather events were also of concern. Interestingly, nations that have already been coping with problems, such as the Dutch with sea level rise and the Norwegians with sea-ice loss, are the least concerned with the impacts of climate change. Citizens declared very little trust in government institutions and their scientists and have the most trust in scientists employed by universities.Lead author Paul Buckley from the Centre for Environment, Fisheries and Aquaculture Science (Cefas) in the United Kingdom explains "the study shows that we don't all engage with issues around climate change impacts on the coast and seas in the same way. Awareness and levels of concern are generally higher for people living closest to the sea, women, Southern Europeans and increases with age. We need to tailor our message given the differences in how audiences across Europe engage with these issues. Making issues that seem remote from people's everyday lives relevant is certainly a challenge.""We are at a time when decisions made will have irreversible consequences and this level of misinformation is a huge vulnerability for society in general and for future generations" says Duarte. "The survey calls for a major shift in the way we communicate climate change with far less emphasis on what changes may occur in the future, as these can be misinterpreted by the public, and we need a greater involvement of university scientists."
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Weather
| 2,017 |
July 6, 2017
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https://www.sciencedaily.com/releases/2017/07/170706071927.htm
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California projected to get wetter through this century
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Under business-as-usual greenhouse gas emissions, climate models predict California will get warmer during the rest of the century and most also predict the state will get drier.
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But, new research, published in the journal The researchers found different rates of precipitation increase for northern, central and southern California. Northern California, which they define as starting just north of Santa Rosa, would increase 14.1 percent. Central California, which starts just south of San Luis Opispo, would go up 15.2 percent. Southern California would actually decrease 3.3 percent.They also found the winter months of December, January and February, when California traditionally gets the bulk of its precipitation, would account for much of the overall increase in precipitation. During those three months, precipitation levels would increase 31.6 percent in northern California, 39.2 percent in central California and 10.6 percent in southern California.All these percentages are in comparison to data from the Global Precipitation Climatology Project observed between 1979 and 1999."Most previous research emphasized uncertainty with regards to future precipitation levels in California, but the overall thought was California would become drier with continued climate change," said Robert Allen, an associate professor at UC Riverside and one of the authors of the paper. "We found the opposite, which is quite surprising."The past uncertainty as to whether California would get more precipitation in the future was due to several factors, including year-to-year variations in individual weather events, shortcomings in models and because California lies within a transition zone, where northern parts of the state are expected to become wetter and southern portions are expected to be drier.Allen, a faculty member in the Department of Earth Sciences, and Rainer Luptowitz, a graduate student working with Allen, analyzed 38 climate models developed around the world to reach their conclusions.They found that warming in the tropical eastern Pacific Ocean sea surface temperatures, an area about 2,500 miles east of the international date line, is the main reason for the predicted increase in precipitation levels.The warming sea surface temperatures encourage a southeastward shift of the jet stream, which helps steer more rain-producing mid-latitude cyclones toward California."Essentially, this mechanism is similar to what we in California expect during an El Nino year," Allen said. "Ultimately, what I am arguing is El Nino-like years are going to become more the norm in California."But, Allen cautions that prediction of an El Nino-like year is no guarantee of a more wet winter in California. The 2015-16 winter was an example of that. Many other climatic factors must be considered.
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Weather
| 2,017 |
July 6, 2017
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https://www.sciencedaily.com/releases/2017/07/170706114608.htm
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Working together to reduce infection in extreme weather events
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Lead researcher Dr Aparna Lal from The Australian National University (ANU) said health researchers were often left out of planning and discussions about the looming climate events.
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Dr Lal said more collaboration could help reduce the number of cases of human parasitic infection (cryptosporidiosis) primarily spread through water in extreme weather events or due to gradual climate change.The Indian Ocean Dipole, a key climate driver in the oceans around Australia, is related to patterns of a human parasitic infection primarily spread through water."Such impacts are usually disproportionately felt by the most vulnerable sections of our population- children and the elderly," Dr Lal said.Dr Lal said as the frequency of positive Indian Ocean Dipole phases is expected to increase, there would be drier conditions for much of Australia."This work provides impetus for research to better anticipate where and in whom climate change may have the greatest effect. The research has the potential to inform public health preparedness and planning," she said.Dr Lal, an applied ecologist from the ANU National Centre for Epidemiology and Population Health, said instances of disease reporting increased during drier than normal conditions."Most of the literature tends to focus on flooding events and increases in infectious diseases spread through water," Dr Lal said."Equally plausible, but much less researched is the potential for drought like conditions to increase the burden of diseases spread through water due to inadequate storage and concentration of bugs in water.Researchers will now look at building models to forecast the arrival of these illnesses, identify regions that typically see the first infections and the specific patient groups likely to be affected.The information will support communities to prepare for anticipated increases in illnesses and will help focus public health action where it is needed most.
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Weather
| 2,017 |
July 5, 2017
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https://www.sciencedaily.com/releases/2017/07/170705182846.htm
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From dry to wet: Rainfall might abruptly increase in Africa's Sahel
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Climate change could turn one of Africa's driest regions into a very wet one by suddenly switching on a Monsoon circulation. For the first time, scientists find evidence in computer simulations for a possible abrupt change to heavy seasonal rainfall in the Sahel, a region that so far has been characterized by extreme dryness. They detect a self-amplifying mechanism which might kick-in beyond 1.5-2 degrees Celsius of global warming -- which happens to be the limit for global temperature rise set in the Paris Climate Agreement. Although crossing this new tipping point is potentially beneficial, the change could be so big, it would be a major adaptation challenge for an already troubled region.
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"More rain in a dry region can be good news," says lead-author Jacob Schewe from the Potsdam Institute for Climate Impact Research (PIK). "Climate change due to greenhouse gases from burning fossil fuels really has the power to shake things up. It is driving risks for crop yields in many regions and generally increases dangerous weather extremes around the globe, yet in the dry Sahel there seems to be a chance that further warming might indeed enhance water availability for farming and grazing." Co-author Anders Levermann from PIK and LDEO of New York's Columbia University adds: "We don't know what the impacts on the ground will be, this is beyond the scope of our study; but imagine the chance of a greening Sahel. Still, the sheer size of the possible change is mindboggling -- this is one of the very few elements in Earth system that we might witness tipping soon. Once the temperature approaches the threshold, the rainfall regime could shift within just a few years."Regions like the central parts of Mali, Niger, and Chad -- which are practically part of the Sahara desert -- could receive as much rainfall as is today registered in central Nigeria or northern Cameroon which boast a richly vegetated tropical climate.Dozens of cutting-edge climate computer simulation systems indicate, on average, a weak wet trend for the Sahel under unabated climate change, so it is well known that there'll likely be some more rain in the region in a warming world. The scientists now took a closer look at those simulations that show the greatest increase, plus 40 to plus 300 percent more rain, while others show only a mild increase or even slight decreases. They find that in these wet simulations, as the surrounding oceans warm, Sahel rainfall increases suddenly and substantially. During the same time the monsoon winds that blow from the Atlantic ocean to the continental interior get stronger and extend northwards. This is reminiscent of periods in earth's history during which, according to paleoclimatic findings, African and Asian monsoon systems alternated between wet and dry, sometimes quite abruptly.The scientists previously identified a self-amplifying mechanism behind the sudden rainfall changes. When the ocean surface temperature increases, more water is evaporated. The moist air drifts onto land, where the water is released. When water vapor turns into rain, heat gets released. This increases the temperature difference between the generally cooler ocean and the warmer landmasses, sucking more moist winds into the continent's interior. This again will produce more rain, and so on. "Temperatures have to rise beyond a certain point to start this process," explains Schewe. "We find that the threshold for this 'Sahel monsoon' is remarkably similar across different models. It seems to be a robust finding.""The enormous change that we might see would clearly pose a huge adaptation challenge to the Sahel," says Levermann. "From Mauritania and Mali in the West to Sudan and Eritrea in the East, more than 100 million people are potentially affected that already now are confronted with a multifold of instabilities, including war. Particularly in the transition period between the dry climatic conditions of today and the conceivably much wetter conditions at the end of our century, the Sahel might experience years of hard-to-handle variability between drought and flood. Obviously, agriculture and infrastructure will have to meet this challenge. As great as it hopefully were for the dry Sahel to have so much more rain," concludes Levermann, "the dimension of the change calls for urgent attention."
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Weather
| 2,017 |
July 5, 2017
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https://www.sciencedaily.com/releases/2017/07/170705164449.htm
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Figuring out how fast Greenland is melting
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A new analysis of Greenland's past temperatures will help scientists figure out how fast the island's vast ice sheet is melting, according to a new report from University of Arizona atmospheric scientists.
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The ice sheet has been shrinking since 1900 and the yearly loss of ice has doubled since 2003, other researchers have shown. The accelerated melting of the Greenland ice sheet is contributing to sea level rise.The glaciers and ice sheet of Greenland cover a land area greater than the European countries of Germany, France, Spain and Italy combined. If all Greenland's ice melted, sea levels would rise by about 7 meters (23 feet).Figuring out how fast the island's ice has melted and will melt in the future requires knowing the past and the present surface air temperatures, according to UA researchers J. E. Jack Reeves Eyre and Xubin Zeng."Greenland is particularly important to global climate change because it has the potential to cause a big change in sea level," lead author Reeves Eyre said. "Knowing how it's going to change over the next century is important."Calculating an average yearly surface temperature for the whole of Greenland is difficult. During most of the 20th century, the only weather stations were along the coast. There was no network of weather stations in Greenland's interior until 1995.Other groups of researchers have used combinations of weather station readings, satellite remote sensing data, statistical analyses and climate models to calculate the island's annual surface temperatures back to 1901. However, the results of those analyses disagree with one another substantially.How Greenland's massive ice sheet will respond to future warming is not well understood, said Zeng, a UA professor of hydrology and atmospheric sciences.By combining the best two of the previous analyses, the UA study provides the most accurate estimates of Greenland's 20th century temperatures, said Reeves Eyre, a doctoral student in the UA Department of Hydrology and Atmospheric Sciences.The finding will help improve climate models so they more accurately project future global climate change and its effects."That's why we look at the historical period -- it's not about the history. It's about the future," said Zeng, who holds the Agnese N. Haury Endowed Chair in Environment.Reeves Eyre and Zeng's research article, "Evaluation of Greenland near surface air temperature data sets," is published online July 5 in the open-access journal NASA, the U.S. Department of Energy and the UA Agnese Nelms Haury Program in Environment and Social Justice funded the research.Knowing Greenland's past temperatures is important for improving climate models, because scientists test regional and global climate models by seeing how well they predict what the climate was in the past.Previous analyses of the island's past temperatures came up with contradictory results: Some said the 1930s were warmer than present, while other analyses said the opposite.To find the best estimate of 20th century temperatures, the UA scientists compared 16 different analyses. The UA team compared more datasets covering the period 1901 to 2014 and used more information from weather stations and field expeditions than previous studies."We are the first to bring all those datasets together," Zeng said.To avoid bias from lumping temperature data from different elevations, Reeves Eyre and Zeng divided the temperature data into three categories: data from coastal regions, data from lower than 1,500 meters (about 4,900 feet) and data from above 1,500 meters.The coastal regions of Greenland are ice-free year-round, whereas the glaciers and ice sheet at the intermediate elevation melt some in the summer, but refreeze in the winter, Reeves Eyre said. The ice sheet and glaciers at the intermediate elevations are shrinking a bit each year because temperatures are increasing.Above 1,500 meters, the ice generally does not melt and may even gain mass, he said. However, the bit of ice gained at the highest elevations does not offset the loss of ice at the lower elevations.The UA study resolves the discrepancies among the other analyses and provides the best estimates of Greenland's past temperatures."The combination of the MERRA2 and GISTEMP (analyses) gives the most accurate results over the 20th century," he said. "Putting them together is more than the sum of the parts. Neither of them individually can do what both of them together can do."Although some previous analyses suggest the 1930s were warmer than it is now, the UA analysis shows that current temperatures are warmer than the 1930s. The long-term trend for Greenland's ice sheet appears to be for ever-higher surface temperatures, he said."By studying a wide range of available data and combining two of the best data sources, we've come up with a combination that best represents the whole distribution of temperatures over Greenland from 1880 to 2016," Reeves Eyre said. "Using this dataset is the best way to evaluate climate models and their projection of temperature change over Greenland."
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Weather
| 2,017 |
July 5, 2017
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https://www.sciencedaily.com/releases/2017/07/170705113111.htm
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Global erosivity map shows differences between climatic regions
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Soil is our most important source of food. And yet, much of the world's soils are being eroded faster than they are formed.
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The capacity of rain to cause soil erosion is known as erosivity. Soil erosion by water is the most serious cause of soil degradation globally. Heavy rainfall and extreme weather events aggravated by climate change increase soil erosion, which ultimately impacts on economies and people's lives.Lack of data on rainfall erosivity patterns across the planet hampers the implementation of effective soil degradation mitigation and restoration strategies.Responding to this shortcoming, the JRC has collected data on rainfall erosivity from 3 625 meteorological stations in 63 countries to establish the first ever Global Rainfall Erosivity Database (GloReDa) and a global erosivity map which illustrates the differences between climatic regions.The highest rainfall erosivity is found in South America (especially around the Amazon Basin) and the Caribbean countries, Central Africa and parts of Western Africa and South East Asia. The lowest values are in mid- and high-latitude regions such as Canada, the Russian Federation, northern Europe, northern Africa, the Middle East and southern Australia.It should be noted that high rainfall erosivity does not necessarily mean high levels of erosion, as factors such as soil characteristics, vegetative cover and land use also have an important impact on soil erosion.The new global erosivity map is a critical input to global and continental assessments of soil erosion by water, flood risk and natural hazard prevention. It provides an important dataset for soil experts and policy makers for raising awareness on the importance of healthy soil for healthy life and for achieving the UN's Sustainable Development Goals.The map is publicly available and can also be used by other research groups to perform national, continental and global soil erosion modelling.
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Weather
| 2,017 |
July 4, 2017
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https://www.sciencedaily.com/releases/2017/07/170704094104.htm
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Extreme weather conditions and climate change account for 40% of global wheat production variability
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JRC scientists have proposed a new approach for identifying the impacts of climate change and extreme weather on the variability of global and regional wheat production. The study analysed the effect of heat and water anomalies on crop losses over a 30-year period.
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JRC scientists studied the relative importance of heat stress and drought on wheat yields between 1980 and 2010. They developed a new Combined Stress Index in order to better understand the effects of concurrent heat and water stress events.The study 'Wheat yield loss attributable to heat waves, drought and water excess at the global, national and subnational scales' was published in Environmental Research Letters earlier this month. It finds that heat stress concurrent with drought or water excess can explain about 40% of the changes in wheat yields from one year to another.One finding is that in contrast to the common perception, water excess affects wheat production more than drought in several countries. Excessive precipitation and greater cloud cover, especially during sensitive development stages of the crop, are major contributors to reduced yields, as they help pests and disease proliferate and make it harder for the plants to get the oxygen and light they need.In 2010, wheat contributed to 20% of all dietary calories worldwide. It therefore has a major role in food security worldwide, some countries being particular reliant on it . As climate change is increasing the duration, frequency and severity of extreme weather events, it has become increasingly urgent to identify their effects and provide early warnings, in order to ensure market stability and global food security.This study helps to better understand the role of weather factors in wheat production and global yield anomalies. It shows, for the first time, the effect of individual extreme events and their impacts on particular development stages of the crop (for example, the effect of drought during key development periods such as flowering and grain-filling).Compared to previous approaches, the Combined Stress Index has the advantage of being able to calculate the effect of single weather anomalies on total crop output at global and regional levels. Moreover, it offers a simple and practical tool to compute yield anomalies using seasonal, climate forecasts and projections, thereby allowing better adaptation studies and mitigation strategies to be established.The model explicitly accounts for the effects of temperature and soil moisture changes (positive and negative) on global and regional wheat production fluctuations.A specific case study was carried out at subnational level in France, where wheat was found to be more sensitive to overly wet conditions. In other countries, heat stress and drought are the most important predictors of crop losses. For instance, in Mediterranean countries, drought has a bigger detrimental effect on wheat yields than heat stress.
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Weather
| 2,017 |
June 29, 2017
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https://www.sciencedaily.com/releases/2017/06/170629101727.htm
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A wave's 'sweet spot' revealed
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For surfers, finding the "sweet spot," the most powerful part of the wave, is part of the thrill and the challenge.
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Scripps Institution of Oceanography at the University of California postdoctoral researcher Nick Pizzo has found the exact location on the wave where a surfer gains the greatest speed to get the best ride.Published this month online in the "Based upon the speed and geometry of the wave, you can determine the conditions to surf a wave and also where on the wave the maximum acceleration, or 'sweet spot,' will be located," said Pizzo, the author of the new paper and an avid surfer.Pizzo and fellow researchers in the Air-Sea Interaction Laboratory at the Scripps Marine Physical Laboratory and Physical Oceanography Research Division are studying the mass, momentum, and energy exchanged between the atmosphere and ocean due to breaking waves, to help improve our understanding of weather and climate.As a wave breaks at the ocean surface, currents are generated and water droplets in the form of sea spray are ejected from the ocean into the atmosphere. These small-scale processes are critical pieces of information to improve weather and climate models to better forecast major storm events and the future climate."The study was motivated by important scientific questions that lead to a better description of the upper ocean to be used in weather and climate models," said Pizzo. "By studying the acceleration of a theoretical surfer on a wave, we can provide a better description of the currents generated by breaking waves, leading to an improved understanding of the momentum and energy budget between the atmosphere and ocean."Breaking waves, like those surfers ride close to shore, are infrequent in the world's oceans. However, according to Pizzo, they are nonetheless fundamental to weather prediction, where, for example, storms and hurricanes are strongly influenced by the physical processes generated by breaking waves, as well as the longer-term evolution of the climate."We need to understand the little things to get the big picture," he added.So, where is the "sweet spot?" Right inside the curl of the breaking wave.
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Weather
| 2,017 |
June 28, 2017
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https://www.sciencedaily.com/releases/2017/06/170628144923.htm
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Concurrent hot and dry summers more common in future
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A combination of severe drought and a heatwave caused problems for Russia in the summer of 2010: fires tore through forests and peat bogs. Moscow was shrouded in thick smog, causing many deaths in the local population. At the same time, Pakistan was engulfed in heavy rain, as the high-pressure area over Russia blocked a low-pressure zone over Pakistan. This led to the country's worst flooding for centuries.
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According to the statistics, however, such extreme climate events, similar to the heatwave that affected large areas of western and central Europe in the summer of 2003, are only supposed to occur around every 100 years. But as global warming pushes average temperatures higher, the frequency of several extreme weather events is set to increase, experts claim.Perhaps the statisticians need to check their figures. Researchers have traditionally studied extreme climate events such as heatwaves and drought in isolation, producing separate forecasts of how frequently each one is likely to occur. But when these extremes coincide -- a combination of hot and dry summers, for example -- their impact is far greater.ETH researcher Jakob Zscheischler and Professor Sonia Seneviratne from the ETH Institute for Atmospheric and Climate Science have now calculated the probability of compound climate extremes, as the co-occurrence of severe heat and drought generally depends on the correlation between temperature and precipitation in the summer. The results of their study have just been published in the academic journal "In their study, Zscheischler and Seneviratne have calculated that the combination of heat and drought is as much as two to four times more frequent than if these two extreme climate events are studied in isolation. In America's mid-west, for instance, the probability of this combination occurring is even up to five times higher.Calculating the probability of these two extremes separately and then combining them is not the same as establishing the likelihood of their co-occurrence. "Our calculations clearly show that compound climate extremes occur much more frequently than previously expected," says the ETH professor.Zscheischler and Seneviratne have analysed the combination of heatwaves and drought because observations show that "there are definite correlations between such compound climate events," she goes on to explain. This was the reason for the extremely hot and dry summer that central Europe experienced in 2015. "These scenarios are becoming more common."In their study, the authors show that the correlation between temperature and precipitation will intensify if climate change remains unconstrained. As a result, very hot and dry summers will become increasingly common.The greater frequency of compound climate extremes also poses a bigger threat to agriculture, society and the economy. If two climate extremes are examined together, the probability of their co-occurrence often rises dramatically due to previously unaccounted dependences -- along with the associated risks. The latest calculations show that the risk is far greater than previously assumed, the ETH professor warns: "We're not properly prepared for this."In terms of health risks, an intense heatwave can lead to dehydration and even premature death in the elderly and very young population. In agriculture, severe drought can ruin crops or lead to escalating irrigation costs. Forest fires are also more frequent in case of co-occurrent droughts and heatwaves, such as for the recent conflagrations in Portugal."If climate extremes are only studied in isolation, we risk underestimating the potential threat," stresses Professor Seneviratne. "In today's highly connected world it is more important than ever to assess these risks accurately."2010 was a classic example of how extreme climate events no longer affect just one country, but can also -- given the interconnectivity of the modern world -- spill over to regions with more stable weather patterns. When wheat yields fell as a result of severe drought, Russia halted exports to Egypt to ensure it could still meet domestic demand for wheat. This ramped up wheat prices in Egypt, badly affecting certain parts of the population and creating political instability.Professor Seneviratne says that climate scientists have traditionally underestimated the effect of compound climate events and have not yet researched them in an appropriate way. This new study is one of the first to address this shortcoming, and help prepare us for what might be in store. "Adjustments will be necessary at all levels," she notes.
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Weather
| 2,017 |
June 28, 2017
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https://www.sciencedaily.com/releases/2017/06/170628095817.htm
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Predicting eruptions using satellites and math
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Volcanologists are beginning to use satellite measurements and mathematical methods to forecast eruptions and to better understand how volcanoes work, shows a new article in
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As magma shifts and flows beneath the earth's surface, the ground above flexes and quivers. Modern satellite technologies, similar to GPS, can now track these movements, and geoscientists are beginning to decipher what this reveals about what's happening underground -- as well as what is likely to happen in the future."We're the first to have developed a strategy using data assimilation to successfully forecast the evolution of magma overpressures beneath a volcano using combined ground deformation datasets measured by Global Navigation Satellite System (more commonly known as GPS) and satellite radar data," explains Mary Grace Bato, lead author of the study and a researcher at the Institut des Sciences de la Terre (ISTerre) in France.Bato and her collaborators are among the first to test whether data assimilation, a method used to incorporate new measurements with a dynamical model, can also be applied in volcano studies to make sense of such satellite data. Meteorologists have long used a similar technique to integrate atmospheric and oceanic measurements with dynamical models, allowing them to forecast the weather. Climate researchers have also used the same method to estimate the long-term evolution of the climate due to carbon emissions. But volcanologists are just beginning to explore whether the technique can also be used to forecast volcanic eruptions."The amount of satellite and ground-based geodetic data (i.e. GPS data) has tremendously increased recently," says Bato. "The challenge is how to use these data efficiently and how to integrate them with models in order to have a deeper understanding of what occurs beneath the volcano and what drives the eruption so that we can determine near-real-time and accurate predictions of volcanic unrest."In their latest research, Bato and her colleagues have begun answering these questions by simulating one type of volcano -- those which erupt with limited "explosivity" due to the build-up of underlying magma pressure. Through their exploratory simulations, Bato was able to correctly predict the excess pressure that drives a theoretical volcanic eruption, as well as the shape of the deepest underground magma reservoir and the flow rate of magma into the reservoir. Such reservoirs are typically miles below the surface and, as such, they're nearly impossible to study with existing methods.Geoscientists still need to improve current volcanic models before they can be widely applied to real-life volcanoes, but Bato and her colleagues are already beginning to test their methods on the Grímsvötn Volcano in Iceland and the Okmok Volcano in Alaska. They believe that their strategy will be a key step towards more accurate predictions of volcanic behavior."We foresee a future where daily or even hourly volcanic forecasts will be possible -- just like any other weather bulletin," says Bato.This research is part of a broader collection of articles focused on volcanic hazard assessment.
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Weather
| 2,017 |
June 21, 2017
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https://www.sciencedaily.com/releases/2017/06/170621145133.htm
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New research leverages big data to predict severe weather
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Every year, severe weather endangers millions of people and causes billions of dollars in damage worldwide. But new research from Penn State's College of Information Sciences and Technology (IST) and AccuWeather has found a way to better predict some of these threats by harnessing the power of big data.
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The research team, led by doctoral student Mohammad Mahdi Kamani and including IST professor James Wang, doctoral student Farshid Farhat, and AccuWeather forensic meteorologist Stephen Wistar, has developed a new approach for identifying bow echoes in radar images, a phenomenon associated with fierce and violent winds."It was inevitable for meteorology to combine big data, computer vision, and data mining algorithms to seek faster, more robust and accurate results," Kamani said. Their research paper, "Skeleton Matching with Applications in Severe Weather Detection," was published in the journal of "I think computer-based methods can provide a third eye to the meteorologists, helping them look at things they don't have the time or energy for," Wang said. In the case of bow echoes, this automatic detection would be vital to earlier recognition of severe weather, saving lives and resources.Wistar, the meteorological authority on the project, explained, "In a line of thunderstorms, a bow echo is one part that moves faster than the other." As the name suggests, once the weather conditions have fully formed, it resembles the shape of a bow. "It can get really exaggerated," he said. "It's important because that's where you are likely to get serious damage, where trees will come down and roofs get blown off."But currently, when the conditions are just beginning to form, it can be easy for forecasters to overlook. "Once it gets to the blatantly obvious point, (a bow echo) jumps out to a meteorologist," he said. "But on an active weather day? They may not notice it's just starting to bow."To combat this, the research focused on automating the detection of bow echoes. By drawing on the vast historical data collected by the National Oceanic and Atmosphere Administration (NOAA), bow echoes can be automatically identified the instant they begin to form. Wang said, "That's our project's fundamental goal -- to provide assistance to the meteorologist so they can make decisions quicker and with better accuracy."By continually monitoring radar imagery from NOAA, the algorithm is able to scan the entire United States and provide alerts whenever and wherever a bow echo is beginning. During times of active severe weather, when resources are likely to be spread thin, it's able to provide instant notifications of the development."But this is just the first step," Kamani commented. With the detection algorithm in place, they hope to one day forecast bow echoes before they even form. "The end goal is to have more time to alert people to evacuate or be ready for the straight line winds." With faster, more precise forecasts, the potential impacts can be significant."If you can get even a 10, 15 minute jump and get a warning out earlier pinned down to a certain location instead of entire counties, that's a huge benefit," Wistar said. "That could be a real jump for meteorologists if it's possible. It's really exciting to see this progress."Envisioning the future of meteorology, the researchers see endless potential for the application of big data. "There's so much we can do," Wang said. "If we can predict severe thunderstorms better, we can save lives every year."
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Weather
| 2,017 |
June 21, 2017
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https://www.sciencedaily.com/releases/2017/06/170621100158.htm
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Ocean predicts future northwestern European and Arctic climate
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A new study in the journal
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"We particularly predict that Norwegian air temperature will decrease over the coming years, although staying above the long-term (1981-2010) average. Winter Arctic sea ice extent will remain low but with a general increase toward 2020," says lead author Marius Årthun, postdoc at the Bjerknes Centre for Climate Research.Time series of observed sea surface temperature along the North Atlantic Current and its poleward extension, the Norwegian Atlantic Current, show that anomalies progress poleward from the subpolar North Atlantic to the Nordic Seas with a time lag of 7-10 years. Higher Nordic Seas temperatures are furthermore associated with higher surface air temperatures and precipitation over Norway, and a reduced Arctic winter sea ice cover.Årthun et al. shows that a significant part of northwestern European and Arctic climate can be predicted by statistically exploiting the predictability arising from the poleward propagation of oceanic anomalies along the Gulf Stream and the strong co-variability between these oceanic anomalies and climate.Climate forecasts are essential for many societal applications and bridges the scientific gap that currently exists between the established fields of weather forecasting and projections of future climate change. It is commonly understood that the ocean, due to its large thermal inertia, is a major source of climate variability and predictability.However, several open questions exist on how and to what extent the ocean influences climate over land. This study detail a key aspect of climate predictability, and offers compelling evidence that oceanic variability exerts a strong influence on climate in the North Atlantic-Arctic region.
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Weather
| 2,017 |
June 20, 2017
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https://www.sciencedaily.com/releases/2017/06/170620093206.htm
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Wet and stormy weather lashed California coast... 8,200 years ago
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The weather report for California 8,200 years ago was exceptionally wet and stormy.
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That is the conclusion of a paleoclimate study that analyzed stalagmite records from White Moon Cave in the Santa Cruz Mountains published online Jun. 20 in The Golden State's 150-year stretch of unusually wet weather appears to have been marked by particularly intense winter storms and coincides with a climate anomaly in Greenland ice cores first detected in 1997. Before this "8.2 ka event" was discovered scientists thought the world's climate had been unusually stable during the Holocene, the geological epoch that covers the last 11,700 years of Earth's history.Since then researchers have associated the distinctive, 3.3-degree Celsius temperature dip in the Greenland ice cores with a catastrophic event: The drainage of two giant glacial lakes (Lake Ojibway and Lake Agassiz) located in northeastern North America caused by the collapse of massive ice sheet that covered much of the continent during the last ice age. In short order, the two lakes dumped enough melt water into the North Atlantic to disrupt the world's oceanic and atmospheric circulation patterns and raise the sea level by somewhere between two to 10 feet. The tremendous freshwater flood has been associated with an extended cold snap in Europe, increased drought in Africa, weakened monsoons in Asia and strengthened monsoons in South America."This is the first high-resolution evidence of the response of the coastal California climate to the most distinctive event in the Holocene. Although the effects appear to have been less severe than in other parts of the world, it provides us with new information about the nature of this global climate event," said Jessica Oster, assistant professor of earth and environmental sciences at Vanderbilt University, who directed the study.Oster is a member of a small community of earth scientists pioneering the use of mineral deposits in caves as proxies for the prehistoric climate. Cave formations, including stalagmites and stalactites, can provide valuable information about the climate for the last 600,000 years. They have a built-in clock: The mineral deposits contain radioactive uranium-234 that decays into thorium-230 at a constant rate so the ratio of the two isotopes is determined by the date the mineral deposit formed. Seasonal variations in water seepage produce layers that can be dated with considerable precision. The ratios of other isotopes in the minerals including oxygen and carbon provide information about the temperature and nature of the vegetation in the region at the time the layers formed. Concentrations of trace elements like magnesium, strontium and phosphorus provide information about how wet the environment was."Events like this are particularly difficult to study because they are so brief," said Oster. "Fast-growing stalagmites are particularly good for this purpose because they have very high temporal resolution."With a five-year grant from the National Science Foundation, Oster is analyzing stalagmites from two California caves in order to shed new light on the factors that produced megadroughts in the region during the late Pleistocene and early Holocene. During her studies, she discovered a stalagmite that was growing rapidly just before, during and after the 8.2 ka event. By analyzing the oxygen and carbon isotope ratios and the concentrations of the trace elements phosphorus and magnesium in the mineral layers formed from 6,900 to 8,600 years ago, Oster and her collaborators extracted a considerable amount of information about what was going on in the prehistoric California atmosphere.According to the paper, ." ..the new record suggests that the 8.2 ka event was associated with a brief period of wetter conditions, potentially arising from increased storminess, and demonstrates a near synchronous climate response to this event on both sides of the Pacific."Climatologists are particularly interested in this prehistoric event because it can provide insight into what would happen if global warming reaches a point where glaciers in Greenland and other parts of the globe melt rapidly enough to dump large amounts of fresh water into the ocean. In 2003, for example, the Office of Net Assessment at the U.S. Department of Defense produced a study of prospective climate change specifically based on this event.
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Weather
| 2,017 |
June 20, 2017
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https://www.sciencedaily.com/releases/2017/06/170620093146.htm
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Simple tactic results in dramatic water conservation, study shows
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Rain or shine has new meaning thanks to an innovative, inexpensive and simple tactic developed by researchers at Florida Atlantic University that will really change how people think about watering their lawns. The tactic? A straightforward road sign.
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Outdoor water restrictions are a common water conservation strategy in the United States, Canada, Australia and other countries to address water use as it relates to maintaining lawns and greenspace. In fact, 29 states in the U.S. have outdoor water restrictions that only allow lawn watering on certain days or times. Conserving water is critical because 50 to 90 percent of household water is used for this purpose. Furthermore, to provide each South Florida lawn with the necessary one-inch of water per week, it takes more than 62 gallons of water for every 10-foot-by-10-foot area.However, this one-pronged approach of water restrictions that involves pre-set and arbitrary lawn-watering schedules does not always result in actual water savings so Tara Root, Ph.D., associate professor in the Department of Geosciences in FAU's Charles E. Schmidt College of Science, and Felicia D. Survis, who recently earned her Ph.D. at FAU, decided to do some research.For two years, which included two annual wet and dry seasons, they conducted a unique study in Wellington, a suburban village in South Florida, to demonstrate how you can save a lot of water by simply providing people with more information than just directives, schedules or guidelines about which days of the week they can water their lawns. Wellington provided the perfect venue for this study since the village is located in a region that has distinct wet and dry seasons and that is subject to permanent year-round mandatory water restrictions. Additionally, Wellington was interested in the research and helped to implement the pilot program. Results of their study are published in the current issue of the "The Rain-watered Lawn," a pilot program, was implemented as a weather-based add-on water conservation strategy to find out if informing lawn-watering behavior is more effective than just having mandatory water restrictions alone. The study involved a total of 627 households that were divided into two groups: 321 households assigned to an experimental group, and 306 households assigned to a control group who were subject to only the existing water restrictions.For the study, the researchers created a highly visible road sign that matched existing road signs, and placed them close to the entrances of the experimental neighborhoods. The purpose of the signs was to communicate rainfall levels in the last seven days and to remind people that most South Florida lawns only need one inch of water per week. The bottom of the sign read: "Is rainfall alone meeting the water needs of your lawn?" At the same time that the signs went up, households in the experimental group received a postcard and leaflet about the signs and informed them that existing water restrictions were not being replaced or modified."We would significantly benefit from a new approach to outdoor water conservation to improve how we conserve water and to help people better recognize and synchronize with the regional water balance," said Survis. "People realize that there is something more meaningful that they could be doing to conserve water besides just following a watering schedule, but they have no clear idea about what to do."For the study, the researchers gathered a long-term data set of residential lawn-watering frequency and lawn-watering behaviors, determined the scale of weekly lawn-watering frequency with water restrictions alone, and tested to determine if adding the weather-based conservation strategy could improve lawn irrigation efficiency and water savings over water restrictions alone. They collected rainfall data from a weather station located close to the study area so that the rainfall totals on the signs were as representative as possible of actual conditions.Results of their research show the greatest impact during the rainier summer weeks with an astounding 61 percent decrease in lawn watering in the experimental households as compared to the control group."This was a particularly powerful finding because virtually all lawn watering during those rainier weeks was unnecessary," said Root. Findings also show that once the significant, initial 61 percent drop in lawn watering occurred shortly after the signs went up during the test year, the experimental group maintained a wide separation from the control group, where they stayed at about 41 percent below the control group. Root and Survis speculate that this continued pattern in the experimental group could be habitual because of the conservation behaviors that occurred during the wet weeks that were carried over into the dryer season."While this program was especially effective in South Florida, a region with distinct seasonal rainfall, this novel approach developed at Florida Atlantic University is broadly applicable to addressing a global issue in any region to better sync lawn-watering conditions with actual conditions," said Ata Sarajedini, Ph.D., dean of FAU's Charles E. Schmidt College of Science. "This program has the added benefit of getting people more in tune with the natural water cycle, which might help urban and suburban residents prepare for changes in water supply policy that may become necessary as the climate changes."The researchers stress that because reductions in lawn water use are closely related to reductions in water contamination, a greater sense of environmental stewardship could be tied to everyday activities such as cutting back on unnecessary lawn irrigation."With some modifications and use of technology such as texting and the internet, a weather-based outreach project like ours could be scaled up for much larger metropolitan areas," said Root.
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Weather
| 2,017 |
June 15, 2017
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https://www.sciencedaily.com/releases/2017/06/170615084601.htm
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Widespread snowmelt in West Antarctica during unusually warm summer
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An area of West Antarctica more than twice the size of California partially melted in 2016 when warm winds forced by an especially strong El Nino blew over the continent, an international group of researchers has determined.
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In the June 15 issue of the journal While researchers have been gathering evidence for years that warm ocean water is melting West Antarctic ice shelves from beneath, this is one of the first times they've been able to document how warm air could also cause widespread melting from above.As it happens, researchers had installed the necessary instruments to investigate these processes in West Antarctica only a few weeks earlier, as part of a study to better understand how clouds affect the amount of energy that reaches the snow surface and influence its temperature."We were extraordinarily fortunate to be able to deploy state-of-the art equipment to West Antarctica just before this large melt event occurred," said Dan Lubin, principal investigator of the Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE). Lubin is a research physicist at the Scripps Institution of Oceanography in La Jolla, California and a coauthor of the "These atmospheric measurements will help geophysical scientists develop better physical models for projecting how the Antarctic ice sheet might respond to a changing climate and influence sea level rise," Lubin added.Julien Nicolas, lead author of the paper, is a research associate at the Byrd Polar and Climate Research Center (BPCRC) at The Ohio State University. He's part of the OSU team that provides weather and climate analysis for AWARE.When Nicolas got a January 2016 alert from the AWARE expedition that the weather at their campsite atop of the West Antarctic Ice Sheet had turned unseasonably warm, he checked to see in the satellite data what was happening to the rest of West Antarctica.The presence of water in the snow is often hard to detect from visible satellite imagery, especially if clouds block the view. Instead, Nicolas analyzed satellite measurements of the microwave radiation emitted by the snowpack, since dry and wet snows have very different microwave signatures.What he saw during the melting event was an area of roughly 300,000 square miles, including most of the Ross Ice Shelf, that likely contained a mix of snow and water."What probably happened is that the surface snowpack was able to contain the meltwater, acting as a buffer and preventing the formation of melt ponds and streams that can be common on some Antarctic ice shelves," Nicolas said, "but we cannot rule out the presence of standing water in many locations."What makes this event particularly interesting to scientists is that it took place during one of the strongest El Nino events on record."This conjunction of events was no coincidence," he said.During an El Nino, warm waters from the equatorial Pacific Ocean move east. El Ninos also favor weather patterns that steer warm air towards West Antarctica, but strong westerly winds that blow over the ocean to the north of the continent usually keep the warmer air at bay.BPCRC senior research associate Aaron Wilson, also a coauthor on the study, used climate models to show that melt events in West Antarctica are more likely to occur during El Nino conditions, especially when westerly winds are weak. What makes this January 2016 event unique, he explained, is that the warming occurred despite strong westerly winds."Without the strong westerlies, it's likely there would have been much more melting," Wilson said.Coauthor David Bromwich, professor of geography and leader of the Ohio State team, explained it this way: "In West Antarctica, we have a tug-of-war going on between the influence of El Ninos and the westerly winds, and it looks like the El Ninos are winning," he said. "It's a pattern that is emerging. And because we expect stronger, more frequent El Ninos in the future with a warming climate, we can expect more major surface melt events in West Antarctica."More frequent melting would accelerate the general deterioration of the ice sheet, he concluded.
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Weather
| 2,017 |
June 12, 2017
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https://www.sciencedaily.com/releases/2017/06/170612170930.htm
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Winning climate strategy demands details
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When understanding a country's climate -- especially vast countries like the United States or China -- to protect food security, biodiversity and human health, the devil is in the details.
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Scientists at Michigan State University (MSU) show that examining the daily minutia of climate, not just temperature, but also sunshine, precipitation and soil moisture simultaneously all over a country gives a better understanding of how variable a land's climate can be. That information is crucial when countries are setting policies aimed at growing food, protecting water supplies and the environment and stemming disease outbreaks. The findings were reported in this week's "There is much talk about how climate is changing and what should be done about it, but in reality, it is the variabilities -- those many changes above and below the norm -- that can have a great impact on coupled human and natural systems," said Jianguo "Jack" Liu, MSU's Rachel Carson Chair in Sustainability and director of the Center for Systems Integration and Sustainability. "A holistic view of our world gives us the most useful information."The team examined the daily variability of four climatic factors simultaneously with data from 1960 to 2013 across China. From this they learned that the climate in the northern regions of China, including the province that grows much of the crops that feed big cities in the south, has the more dramatic swings. Yet that's also an area in which farmers are shifting crops to corn over soybeans, even though corn is dependent on a long growing season."Our study shows that it's not enough to say 'a nation is experiencing climate change' because the reality is that climate is made up of several daily factors," said Zhenci Xu, the PhD student who is the study's lead author. "It is variability that indicates the degree of fluctuation and uncertainty of the climate change process."It's the chaos of climate change that can wreak havoc with growing plants or the survival rates of bacteria and viruses. Climate variability also weighs heavily on agriculture and economic development.This study is the first time the variability and trends of four climactic factors have been analyzed.Northern China's monthly and seasonal variability of the climate systems is generally larger than that of south China. The report also singles out more subtle differences in climate events across the country.Xu also said countries should consider more meteorological stations in areas known to have more complex climate dynamics along with human interests that are sensitive to the vagaries of weather.And Liu said countries would be wise to examine how local climate events can have a global impact through telecoupling processes, as a monsoon in one corner of the world can blanket another country with moist air and heat."Climate can't see borders, but people can and we must learn to look at the big picture with a very small lens," Liu said.
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Weather
| 2,017 |
June 8, 2017
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https://www.sciencedaily.com/releases/2017/06/170608123718.htm
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Where climate change is most likely to induce food violence
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While climate change is expected to lead to more violence related to food scarcity, new research suggests that the strength of a country's government plays a vital role in preventing uprisings.
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"A capable government is even more important to keeping the peace than good weather," said Bear Braumoeller, co-author of the study and associate professor of political science at The Ohio State University.While previous studies had examined the impact of climate change-induced weather patterns on violence and the increased danger of violence in weak or failing states, this is the first study to demonstrate that the combination of the two risk factors is even more dangerous than they would be separately.Braumoeller conducted the study with his former doctoral students Benjamin Jones, now at the University of Mississippi, and Eleonora Mattiacci, now at Amherst College.Their results appear in the "We've already started to see climate change as an issue that won't just put the coasts under water, but as something that could cause food riots in some parts of the world," Braumoeller said.Extreme weather such as droughts and floods could hurt agricultural production in some countries, leading to violence there or elsewhere by people who are desperate for food."Climate-induced food scarcity is going to become an increasingly big issue and we wanted to understand which countries are most threatened by it," he said.The researchers estimated the effects of food insecurity and state vulnerability on the occurrence of violent uprisings in Africa for the years 1991 to 2011.The researchers used a variety of measurements for both food shocks that lead to violence and to gauge the vulnerability of countries.For the climate-related causes of food shocks, the researchers analyzed rainfall, temperature and -- importantly -- the international prices of food, including sudden increases in prices."We recognized that countries that imported food could be impacted by climate shocks in other parts of the world that suddenly increased prices, even if they weren't experiencing any significant weather impacts themselves," Braumoeller said.When examining countries' vulnerabilities, the researchers analyzed a host of factors including a country's dependence on agricultural production, its imports, the strength of its political institutions and its wealth."We found that the most vulnerable countries are those that have weak political institutions, are relatively poor and rely more on agriculture," he said."Less vulnerable countries can better handle the problems that droughts or food price fluctuations create."These results suggest ways that the United States and the worldwide community can respond to these challenges.Addressing the vulnerabilities of countries is "crucial to breaking the link between food insecurity and violence," Braumoeller said.That means more than providing food aid to offset shortages in the short-term. More broadly, efforts should be focused on strengthening government institutions in vulnerable countries and helping them invest in "green growth" policies aimed at increasing economic growth while fostering resilience to climate shocks, he said."Development aid is important now and it is likely to be even more important in the future as we look for ways to increase climate resilience," Braumoeller said.
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Weather
| 2,017 |
June 7, 2017
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https://www.sciencedaily.com/releases/2017/06/170607163029.htm
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Small climb in mean temperatures linked to far higher chance of deadly heat waves
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An increase in mean temperature of 0.5 degrees Celsius over half a century may not seem all that serious, but it's enough to have more than doubled the probability of a heat wave killing in excess of 100 people in India, according to researchers at the University of California, Irvine and other institutions.
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This could have grim implications for the future, because mean temperatures are projected to rise by 2.2 to 5.5 degrees Celsius by the end of this century in the low- and mid-latitude countries of the Asian subcontinent, the Middle East, Africa and South America."The impact of global climate change is not a specter on the horizon. It's real, and it's being felt now all over the planet," said Amir AghaKouchak, UCI associate professor of civil & environmental engineering and co-author of the study, published in Using data gathered by the India Meteorological Department from 1960 to 2009, the UCI-led team analyzed changes in summer temperatures; the frequency, severity and duration of heat waves; and heat-related deaths.They found that when mean summer temperatures in the South Asia nation went from 27 to 27.5 degrees Celsius, the probability of a heat wave killing more than 100 people grew from 13 percent to 32 percent -- an increase of 146 percent.In real terms, there were only 43 and 34 heat-related fatalities in 1975 and 1976, respectively, when the mean summer temperature was about 27.4 degrees Celsius. However, at least 1,600 people died from excessive heat in 1998, when the mean summer temperature was higher than 28 degrees Celsius.The average number of heat wave days over the five-decade study period was 7.3 per year. The most heat wave days occurred in 1998 (18), when 1,655 people died, and 2003 (13), when 1,500 people died.India is currently home to over 1.3 billion people, nearly a quarter of whom live on less than $1.25 a day and have little to no access to electricity."In addition to India, populations in other developing countries in low- to mid-latitude regions are especially hard hit by these extreme heat events," said lead author Omid Mazdiyasni, a UCI graduate student in civil & environmental engineering. "They lack air conditioning that people in richer countries rely on when the heat is unbearable, and they don't have funds to escape to cooler climates."The study authors stressed that their findings should serve as a wake-up call for governments and international organizations to help improve the resilience of areas most vulnerable to climate change-induced weather events. But in the wake of last week's news of the United States withdrawing from the Paris climate accord, they acknowledged the difficulty in building a broad-based coalition to tackle the issue."Given the quantifiable impacts of climate change in India and other developing nations in the coming decades, both rich and poor countries should be ramping up our efforts to combat global climate change instead of turning our backs on commitments we have made to the international community," said co-author Steven J. Davis, UCI associate professor of Earth system science.
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Weather
| 2,017 |
May 31, 2017
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https://www.sciencedaily.com/releases/2017/05/170531091448.htm
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1976 drought revealed as worst on record for British butterflies and moths
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Scientists at the University of York have revealed that the 1976 drought is the worst extreme event to affect butterflies and moths in the 50 years since detailed records began.
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The summer of 1976 saw standpipes in the streets and billions of seven-spot ladybirds swarming in search of food. It was the hottest English summer since records began over 350 years ago -- the mercury topped 32 °C for 15 consecutive days across much of southern England, and some regions received no rain for 45 days straight.Since then, the UK has warmed by a full degree Celsius and experienced numerous bouts of extreme weather, from heavy rainfall and flooding to heatwaves and drought; yet no single year has caused so many butterfly and moth species to crash simultaneously.Measuring 50 years of butterfly and moth data against extreme weather events since 1968, scientists looked for years in which an unusual number of species responded in synchrony, with 1976 found to be the most devastating."It was the culmination of a two-year event." said Dr Phil Platts, Postdoctoral Research Associate in York's Department of Biology and co-author of the study. "Hot and dry conditions stretched back to the spring of 1975. This was initially good for butterflies and moths, and their numbers boomed. But then extreme heat and sustained drought in the summer of 1976 tipped the balance, causing numbers to plummet across at least 50 different species."The study also looked at the impact of extreme weather on birds, determining that the cold winter of 1981-82 had the biggest effect on their numbers. A third of bird species crashed as temperatures fell as low as -26 °C.Researchers concluded, however, that for many of our widespread species, occasional extreme weather events have not, to date, had a lasting impact on population trends."This seems to be truer of short-lived species that can multiply rapidly, like butterflies and moths, than of the birds we studied." said Professor Tom Brereton, co-author and Head of Monitoring at Butterfly Conservation. "For most species, current evidence suggests long-term declines are being dominated by factors such as habitat loss and intensive farming methods."However, global warming is projected to increase the frequency of extreme weather events such as heatwaves and drought, and it is likely that some of these will generate even greater population changes than we have seen so far. This April was the warmest on record in the UK, and the second warmest globally, beaten only by April 2016.The flip side, adds Dr Platts, is that cold extremes will become increasingly rare: "Species may be released from historical constraints, such as extreme cold, just as they may be hampered by the new extremes."Professor Chris Thomas, senior author in York's Department of Biology, said: "If we want to avoid a future super-heated drought that will put 1976 in the shade, then we need to address the root cause of climate warming -- greenhouse gas emissions. Continued warming will gradually increase the chances that events that are as severe as 1976, or even more extreme, will take place over the coming century."
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Weather
| 2,017 |
May 24, 2017
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https://www.sciencedaily.com/releases/2017/05/170524141748.htm
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Countries most affected by weather disasters do not spend more on weather services
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Countries hit hardest by weather-related disasters do not necessarily spend more on commercial weather and climate information services that assist in preparing for these events, a new study finds. Identifying countries for which this is true and improving the design and delivery of weather and climate services in these locations could lead to better decision-making regarding risks and challenges, ultimately helping to save lives, protect infrastructure, and move people out of poverty.
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Lucien Georgeson and colleagues studied private and public organizations' spending on weather and climate information services in over 180 countries between 2010 and 2015, identifying imbalances based on region and development status.In general, there was no relationship between countries most affected by weather events and spending per capita, the authors say. The region that spent the most was East Asia and the Pacific at $16.5 billion in 2014-2015, whereas Sub-Saharan Africa spent less than $1.4 billion in the same time period.On average, very highly developed countries spent $21.36 per capita, while countries classified as low-income by the World Bank spent less than $1 per capita, on average. However, developing countries committed a higher percentage of their gross domestic product to weather and climate information services, perhaps indicating these countries recognize the value of such services.Taken together, the findings indicate a need to increase information services for the most climate-vulnerable developing countries, the authors say, especially as some researchers have argued that poverty reduction in a number of countries, particularly in Africa, has been "held back" by recent climate variability and extremes.
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Weather
| 2,017 |
May 24, 2017
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https://www.sciencedaily.com/releases/2017/05/170524140716.htm
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Population only part of tornado casualty story
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New research out of Florida State University shows that the strength of a tornado has a significantly larger effect than population on the number of casualties.
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"It's somewhat surprising because we're led to believe it's just a problem with exposure -- the more people in the way, the more casualties," said James Elsner, chair of the FSU Department of Geography and Earl & Sofia Shaw Professor.That's not the case, according to this latest study.Using a regression model, researchers found that on average a doubling of the population under the path of a tornado leads to a 21 percent increase in the casualty rate, while a doubling of the energy dispersed by the tornado leads to a 33 percent increase in the casualty rate."We brought in external data and estimated tornado energy based on tornado area, median wind speeds and the magnitude of those storms," said lead author Tyler Fricker, a doctoral student in the Department of Geography.Fricker and Elsner collaborated on the study recently published in The research team also noted population density within the tornado path usually decreases with stronger storms. A possible reason for this inverse relationship is likely due in part to the fact that the stronger the tornado, the larger its area, making it more likely that the storm will pass through undeveloped or underdeveloped landscapes.In addition, the strongest tornadoes with the potential for producing the most damage tend to occur in the western United States where population density is lower.Although the study is a starting point, Fricker said, the research can begin to inform emergency managers today."Emergency managers can look at results like this," Fricker said. "For instance, a county manager could look at this model and get some kind of estimate of the percent increase in casualties they could see, based on an increase in population."The team also recognizes how climate change can potentially impact future storms. Elsner said the warming atmosphere could lead to fewer storms, but when they come, they could come in bunches or be much stronger."It's not just about human activity and the exposure problem," Elsner said. "It's also about the problem that these storms might change in the future. Through this research, we'll have some way of understanding if they do change, how many more casualties we can expect."Casualties on a per person basis are going down according to Elsner. The chance of being killed in a tornado today is less than it was 30 years ago. That's largely due to better warnings and increased awareness of the threat.Still, Fricker plans to conduct further research to identify certain parts of the United States where higher rates of casualties can be expected."If we can identify certain areas that are more susceptible to casualties the next step is to think about what's actually happening at the surface," Fricker said. "What are the socio-economic and demographic variables that are present in those areas that are affecting tornado casualties?"Poverty levels, education levels and even race might be determinants of casualties according to researchers."We want to try to understand this," Elsner said. "I think the National Weather Service does a great job in warning people, but perhaps some people need to be warned a different way, at a different time of day. There are different ways to communicate the threat. In the future, I think the weather service will able to use that information to pinpoint their watches and warnings even better."
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Weather
| 2,017 |
May 24, 2017
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https://www.sciencedaily.com/releases/2017/05/170524084602.htm
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Wind blows young migrant birds to all corners of Africa
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Migrant birds that breed in the same area in Europe spread out across all of Africa during the northern winter. A new satellite-tracking study shows that the destination of individual birds is largely determined by the wind conditions they encounter during their first migration. The results were made available open access in the peer-reviewed journal
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Until now little was known about how birds learn to migrate. Many young migrant birds die on their way to Africa, due to starvation, exhaustion or predation, or because they fall victim to hunters or collide with power lines and other human-made structures along the way. Wouter Vansteelant, lead author of the study, explains: ´As researchers we take a risk by tracking young birds with expensive tracking devices. Until now most people studied adult birds because they have a higher chance of survival. For this study, however, we decided to place satellite-tracking devices on 31 young honey buzzards that hatched from the egg in southwestern Finland.´Of the 31 honey buzzards, 27 were able to start their first migration to Sub-Saharan Africa. Vansteelant: ´Twenty-four of these birds survived their first migration, ending up as far west as Mali and as far east as the Congo. The most western bird was located more than 3300km from the most eastern bird.´ The research team found that the location where the birds had ended up further west or east depended on the wind conditions they encountered along the way. ´We also saw that some individuals deviated from their average course to cross barriers. A quarter of the honey buzzards, for example, avoided the Baltic Sea by flying over land through Scandinavia, and therefore ended up further west than other birds, and further west than expected from the wind conditions they encountered alone´.That young honey buzzards allow themselves to be drifted by the winds shows that their wintering destination is not predetermined genetically and that chance weather events decide where each individual will return to winter for the rest of its life. Vansteelant: ´We suspect this strategy is very common among migrant birds and probably developed at a time when plenty of suitable wintering habitats were available across the whole breadth of tropical Africa.´ It remains to be seen if that strategy will remain viable under ongoing habitat destruction due to intensification of agriculture, deforestation and climate change. ´If we want to conserve European breeding populations of migrant landbirds, we should focus on measures that will ensure preservation of suitable landscapes for these birds across many developing Sub-Saharan countries rather than the creation of a couple of scattered reserves.´
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Weather
| 2,017 |
May 24, 2017
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https://www.sciencedaily.com/releases/2017/05/170524084403.htm
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Heavier precipitation in the northeast began in 1996
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Over the past century, the Northeast has experienced an increase in the number of storms with extreme precipitation. A Dartmouth-led study finds that the increase in extreme Northeast storms occurred as an abrupt shift in 1996, particularly in the spring and fall, rather than as a steady change over several decades. The findings were published in an early online release of the American Meteorological Society's
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With climate change, a warmer atmosphere is able to hold more moisture, which is likely to affect the frequency, intensity and location of extreme precipitation. Understanding historical changes in extreme storms, including in the Northeast, can improve our understanding of future precipitation projections with continued climate change."Looking at where the increases in extreme precipitation are occurring across the Northeast, interestingly we find that it's not just one part of the Northeast, say the coast, that is experiencing more heavy rainfall events, it's relatively uniform across the region," says Jonathan M. Winter , assistant professor of geography at Dartmouth, who served as one of the co-authors of the study.For the study, the Northeast is defined as Maine, New Hampshire, Vermont, Mass., Conn., R.I., N.J., N.Y., Pa., Md., DC, Del., and W.Va., and draws on weather station data from the Global Historical Climatology Network, which is compiled by the National Oceanic and Atmospheric Association National Climatic Data Center. The threshold for extreme precipitation events depends on the station but regionally averaged is about 2 inches or more of rain in a day.Previous research has referred to the increase in precipitation from 1901 to 2014 as a long-term increase that took place over several decades based on a linear analysis of the data. By analyzing individual changepoints or places where the precipitation record "jumps," this study takes a different approach and finds that these extreme precipitation changes were not consistent with a long-term increase but were in fact due to a shift in extreme precipitation in 1996. From 1996 to 2014, the extreme precipitation in the Northeast was 53 percent higher than from 1901 to 1995. These increases applied to the entire Northeast region except for far western N.Y. and Pa., and a few areas in the mid-Atlantic. Given that the wetter period occurred towards the end of the defined period of the study from 1996 on, the authors note that a linear analysis may not be the most accurate in representing broader changes because the observed precipitation change will vary depending on the time period considered, especially the start date.The study also looks at changes in precipitation across all seasons, finding that the increases in extreme precipitation were driven by extreme storms particularly in the spring and fall. The amount of heavy rainfall from 1996 to 2014 was 83 percent and 85 percent higher in the spring and fall, respectively, than from 1901 to 1995. Tropical cyclones and nor'easters may be the possible key drivers for such changes in the spring and fall.With tropical cyclones in the fall, nor'easters in the winter and spring, and frontal changes in the summer, the Northeast's weather is largely affected by such seasonal systems. Through future work, the researchers plan to study what is driving the increases in total and extreme precipitation since 1996, and will look at the specific weather events associated with these changes.
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Weather
| 2,017 |
May 23, 2017
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https://www.sciencedaily.com/releases/2017/05/170523083724.htm
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Weather patterns' influence on frost timing
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Gardeners know the frustration of a false spring. Coaxed outside by warm weather, some people plant their gardens in the spring only to see a sudden late frost strike at the plants with a killer freezer burn. Grumbling green thumbs, along with farmers and water supply managers, would benefit from more accurate predictions of the first and last frosts of the season.
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Such timing is in flux, however. The frost-free season in North America is approximately 10 days longer now than it was a century ago. In a new study, published today in "The frost-free season has been lengthening over the past century, and now we understand the changes in atmospheric circulation that are extremely strong in frost timing, even stronger than global warming," says University of Utah atmospheric sciences professor Court Strong.Weather and climate are complex systems, with many factors affecting what the particular weather conditions might be in a certain place at a certain time. Previous research, says Gregory McCabe, of the USGS in Denver has focused on the role of large-scale phenomena like El Niño. "I don't think anyone has broken it down to look at the circulations patterns specific to the timing of frost," McCabe says.Strong and McCabe set out to investigate the relative contributions of the global warming trend and local atmospheric circulation patterns to the century-long lengthening of the frost-free season."If you ask a U.S. forecaster what determines the first fall frost, they'll say a cold air mass coming down out of Canada, clearly due to circulation," Strong says. "There's a role for warming, but on the other hand forecasters will tell you there's clearly a role for circulation as well."To more accurately capture regional, relatively small-scale circulation patterns, Strong and McCabe divided the United States into four regions, and examined separately how frost timing patterns varied in each region over 93 years of weather data.The researchers found that atmospheric circulation patterns accounted for between 25 and 48 percent of the variation in frost timing. To put that in context, Strong says, remember that the frost-free season has lengthened by an average of 10 days over the past century. Three to five of those days can be accounted for by atmospheric circulation, while three days can be chalked up to global warming. Other factors, such as local cloud cover, may account for the remaining two to four days.Although the results show that atmospheric circulation is the primary driver of frost timing, the warming trend exerts an influence over circulation beyond the general trend of warming temperatures. "We also found evidence that these circulation patterns themselves have been altered by global warming, especially in the Western U.S. and the Northwest," Strong says. "Warming is an important part of this narrative despite this finding that circulation is a stronger driver historically."Next, Strong and McCabe will evaluate how well climate models capture the drivers of frost timing and look for ways the models can be improved. Better modeling of atmospheric patterns leads to more accurate forecast of future frost timing. "The year-to year variability in climate is controlled by these changes in atmospheric circulation," McCabe says. "On top of that you have the warming trend. If you don't get these patterns right then the simulations are going to have a lot of uncertainty in them."
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Weather
| 2,017 |
May 18, 2017
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https://www.sciencedaily.com/releases/2017/05/170518104012.htm
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GIS: A powerful tool to be used with caution
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Although computer models of archaeological sites are ideal software tools for managing spatially referenced data and commonly used to yield insights which contribute to the protection of heritage materials, some scientists question their credibility, calling for these long-term trends be 'ground truthed' in order to ensure that calculated rates of change reflect observed phenomena 'in the field'. This is particularly true in areas which tend to experience more pronounced and cumulative impacts of modern climate change.
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A recent study by Michael J. E. O'Rourke from the University of Toronto, published in Using GIS methods to compile shoreline positions from archival aerial photography helps indicate valuable long-term trends when assessing shoreline erosion in the vicinity of archaeological sites. The author observed, however, that single episodes of extreme erosion resulting from increasingly volatile weather patterns in recent years have a serious impact on the reliability of shoreline erosion models, suggesting the use of more current imagery sources procured over shorter time intervals.In this case, researchers produced a historical model of shoreline erosion for the Kugmallit Bay area, located along the Beaufort Sea coast in the Canadian Northwest Territories and processed the photography using ESRI's ArcGIS software and the U.S. Geological Survey's Digital Shoreline Analysis System. To assess the accuracy of this model they conducted two field surveys in 2013 and 2014 and found that the model significantly played down the change rates in the vicinity of Imnaaluk. Only then, the model was reviewed for errors and revised using recent satellite imagery secured through a DigitalGlobe Foundation Imagery Grant. Finally, they accounted for weather and sea-level records to determine the possible cause of the observed discrepancy.But the review of analytical methods actually suggested that the model was an adequate means of calculating long-term trends in coastal change rates. The weakness of the model, however, was related to its lack of recent temporal resolution, which proves necessary to account for periodic episodes of extreme erosion taking place within the Kugmallit Bay area.Scientists recommend using the system with caution: While change rates generated by such methods can be useful in highlighting areas at risk in a general sense, they can be limited by the increasingly volatile weather conditions. Given that rates of erosion within the study area reach as high as nine meters of shoreline loss per year, semi-regular imagery updates would be required to adequately manage coastally situated archaeological features."O'Rourke provides a clear, well-researched perspective on the serious impacts that climate change is having on the heritage resources of northern coasts," says Dr. Christopher B. Wolff from the University at Albany. "As an archaeologist who studies Arctic and Subarctic coastal peoples, erosion associated with intense storm activity, loss of permafrost, rising sea levels, and increasing human activity is devastating to comprehend; however, this study not only documents those processes, but provides a means to examine their highly variable impacts that, hopefully, can lead to constructive ways to prioritize research and mitigate destructive processes in this extremely important region."
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Weather
| 2,017 |
May 17, 2017
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https://www.sciencedaily.com/releases/2017/05/170517111618.htm
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Space weather events linked to human activity
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Our Cold War history is now offering scientists a chance to better understand the complex space system that surrounds us. Space weather -- which can include changes in Earth's magnetic environment -- are usually triggered by the sun's activity, but recently declassified data on high-altitude nuclear explosion tests have provided a new look at the mechansisms that set off perturbations in that magnetic system. Such information can help support NASA's efforts to protect satellites and astronauts from the natural radiation inherent in space.
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From 1958 to 1962, the U.S. and U.S.S.R. ran high-altitude tests with exotic code names like Starfish, Argus and Teak. The tests have long since ended, and the goals at the time were military. Today, however, they can provide crucial information on how humans can affect space. The tests, and other human-induced space weather, are the focus of a comprehensive new study published in "The tests were a human-generated and extreme example of some of the space weather effects frequently caused by the sun," said Phil Erickson, assistant director at MIT's Haystack Observatory, Westford, Massachusetts, and co-author on the paper. "If we understand what happened in the somewhat controlled and extreme event that was caused by one of these human-made events, we can more easily understand the natural variation in the near-space environment."By and large, space weather -- which affects the region of near-Earth space where astronauts and satellites travel -- is typically driven by external factors. The sun sends out millions of high-energy particles, the solar wind, which races out across the solar system before encountering Earth and its magnetosphere, a protective magnetic field surrounding the planet. Most of the charged particles are deflected, but some make their way into near-Earth space and can impact our satellites by damaging onboard electronics and disrupting communications or navigation signals. These particles, along with electromagnetic energy that accompanies them, can also cause auroras, while changes in the magnetic field can induce currents that damage power grids.The Cold War tests, which detonated explosives at heights from 16 to 250 miles above the surface, mimicked some of these natural effects. Upon detonation, a first blast wave expelled an expanding fireball of plasma, a hot gas of electrically charged particles. This created a geomagnetic disturbance, which distorted Earth's magnetic field lines and induced an electric field on the surface.Some of the tests even created artificial radiation belts, akin to the natural Van Allen radiation belts, a layer of charged particles held in place by Earth's magnetic fields. The artificially trapped charged particles remained in significant numbers for weeks, and in one case, years. These particles, natural and artificial, can affect electronics on high-flying satellites -- in fact some failed as a result of the tests.Although the induced radiation belts were physically similar to Earth's natural radiation belts, their trapped particles had different energies. By comparing the energies of the particles, it is possible to distinguish the fission-generated particles and those naturally occurring in the Van Allen belts.Other tests mimicked other natural phenomena we see in space. The Teak test, which took place on Aug. 1, 1958, was notable for the artificial aurora that resulted. The test was conducted over Johnston Island in the Pacific Ocean. On the same day, the Apia Observatory in Western Samoa observed a highly unusual aurora, which are typically only observed in at the poles. The energetic particles released by the test likely followed Earth's magnetic field lines to the Polynesian island nation, inducing the aurora. Observing how the tests caused aurora, can provide insight into what the natural auroral mechanisms are too.Later that same year, when the Argus tests were conducted, effects were seen around the world. These tests were conducted at higher altitudes than previous tests, allowing the particles to travel farther around Earth. Sudden geomagnetic storms were observed from Sweden to Arizona and scientists used the observed time of the events to determine the speed at which the particles from the explosion traveled. They observed two high-speed waves: the first travelled at 1,860 miles per second and the second, less than a fourth that speed. Unlike the artificial radiation belts, these geomagnetic effects were short-lived, lasting only seconds.Atmospheric nuclear testing has long since stopped, and the present space environment remains dominated by natural phenomena. However, considering such historical events allows scientists and engineers to understand the effects of space weather on our infrastructure and technical systems.
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Weather
| 2,017 |
May 16, 2017
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https://www.sciencedaily.com/releases/2017/05/170516114315.htm
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Warm weather increases the incidence of serious surgical site infections
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Surgical site infections, a common healthcare-associated infection, are seasonal -- increasing in the summer and decreasing in the winter-according to new research published online today in
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"We show that seasonality of surgical site infections is strongly associated with average monthly temperature. As temperatures rise, risk increases," said Philip M. Polgreen, MD, senior author of the study, Director of the Innovation Lab at The Signal Center for Health Innovation and Associate Professor of Internal Medicine and Epidemiology at the University of Iowa. "However, the odds of any one person getting an infection are still small, and due to the limitations of our data, we still do not know which particular surgeries or patients are at more risk from higher temperature."Researchers used data on millions of patients from the Nationwide Inpatient Sample -- the largest database of discharges from hospitals in the United States -- to identify every adult hospitalization with a diagnosis of SSI from January 1998 to November 2011. Each hospital's longitude and latitude were used to identify nearby weather stations. Monthly summary statistics from each station were included in the analysis, including temperature, rainfall and wind speed. In addition to reviewing incidence of SSIs in a linear time trend to determine the role of seasonality, the study included subgroup analyses by hospitals' region, teaching status and setting (i.e., urban vs. rural), as well as patient gender and age.SSIs were found to be seasonal, with 26.5 percent more SSI-related hospital discharges in the peak month of August than at the low point of January. Researchers estimated that a 25 percent reduction in the average number of at-risk surgeries in the months of July and August would be associated with a decrease of nearly 1,700 SSIs each year. Seasonality and incidence were similar across all regions, age groups, genders and hospital teaching categories, but seasonality was greatest among patients in their 40s and 50s."These results tell us that we need to identify the patients, surgeries, and geographic regions where weather-related variables are most likely to increase patients' risk for infections after surgery," said Christopher A. Anthony, MD, the first author of the study and surgery resident physician at University of Iowa Roy J. and Lucille A. Carver College of Medicine. "This way, we can identify the patients at the greatest risk for surgical site infections during warmer summer months."SSIs can be a major cause of severe illness or death after surgery. SSIs also cause increased use of antibiotics and other antimicrobials, and are a leading cause of hospital readmissions, contributing to excess healthcare costs.
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Weather
| 2,017 |
May 16, 2017
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https://www.sciencedaily.com/releases/2017/05/170516104732.htm
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Extreme weather has greater impact on nature than expected
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An oystercatcher nest is washed away in a storm surge. Australian passerine birds die during a heatwave. A late frost in their breeding area kills off a group of American cliff swallows. Small tragedies that may seem unrelated, but point to the underlying long-term impact of extreme climatic events. In the special June issue of
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Extremes, outliers, cataclysms. As a field of biological research it's still in its infancy, but interest in the impact of extreme weather and climate events on nature is growing rapidly. That's partly because it is now increasingly clear that the impact of extreme events on animal behaviour, ecology and evolution could well be greater than that of the 'normal' periods in between. And partly because the frequency of such events is likely to increase, due to climate change.But how do we define extreme events in the first place? That's problematic, explain NIOO researchers Marcel Visser and Martijn van de Pol. "For climatologists, weather has to be warmer, colder or more extreme in another way than it is 95% of the time. But that doesn't necessarily make it extreme in terms of its impact on nature. There isn't a 1 to 1 correspondence."According to the researchers and a group of international colleagues, most of the evidence suggests that the impact varies depending on the species and the circumstances. "Obviously for a bird, the impact of a couple of extremely cold days in December wouldn't be the same as in April or May, when there are chicks in the nest." This makes it very difficult to predict the consequences of extremes."We also don't know enough about the long-term consequences for nature of these crucially important extremes," say Van de Pol and Visser. "But that could be about to change." As guest editors of a themed issue of the world's oldest scientific journal, dedicated to extreme climatic events, they take stock of the available knowledge and the hiatuses that currently exist. They suggest a 'roadmap' for the further development of this new area of research, aimed at making it easier to compare and synthesize information across fields.An added complication is that storm surges, heatwaves of five days or longer and decades of drought tend to be quite rare. But when they do occur, the consequences are often catastrophic: a challenging combination for researchers. Van de Pol: "Take the Wadden Sea. At the end of the 12th century, there was a storm that utterly transformed the Wadden Sea. The ecological consequences of that storm have continued for decades, if not centuries." "Or take the dinosaurs," adds Visser. "They never recovered from the impact of a single meteorite in Mexico."Less cataclysmic events, too, can have major consequences. Two examples from Phil. Trans. B are oystercatchers that build their nests close to the coast despite rising sea levels, and fairy-wrens -- Australian passerine birds -- that are increasingly exposed to heatwaves and high temperatures, with sometimes fatal consequences.Just imagine you're an oystercatcher: one moment you sit there peacefully incubating your eggs on the saltmarsh, and the next your nest is gone. Engulfed by the Wadden Sea during a storm surge. Time-lapse footage from researchers on the Wadden island of Schiermonnikoog clearly demonstrates the danger. Van de Pol. "We've studied these nests for two decades, and during that time the number of flooding events has more than doubled. Yet the oystercatchers don't take any action."The researchers were keen to find out if the birds would learn from experience and build their nests on higher ground -- safer but further from their favourite sea food, "but they don't." This could result in natural selection based on nest elevation, with only breeders who build their nest on high ground likely to survive. But this could affect the future viability of the population.The other example looks at the impact on two species of passerine birds of a decrease in the number of cold spells and an increase in the number of heatwaves. The red-winged fairy-wren and the white-browed scrubwren both have their habitat in southwestern Australia and they are ecologically quite similar. So how do they respond over time? Do they change their body size to mediate the impact of the extreme temperatures? Van de Pol: "Data over nearly 40 years shows that the two species, although quite similar, respond in completely different ways."So could rare extreme events be more likely to determine the success or failure of populations than the much longer 'normal' periods in between?"Let's say you've studied a breeding population of migratory birds for 49 years," explains Marcel Visser, "and year after year, the birds that arrive early in spring have the most chicks. It's hard to understand why more birds don't arrive early. Then, in the 50th year, a night of extremely cold weather suddenly kills 80% of the early arrivals, while the latecomers escape from the massacre. This may explain why the late birds are so successful at passing on their traits."If that makes it sound as if it's really very hard to make predictions, Visser agrees. "It's not exactly rocket science," he says,"with its complex and elaborate calculations. In fact, it's much more difficult than that!"
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Weather
| 2,017 |
May 15, 2017
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https://www.sciencedaily.com/releases/2017/05/170515125939.htm
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Key differences in solar wind models
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The challenge of predicting space weather, which can cause issues with telecommunications and other satellite operations on Earth, requires a detailed understanding of the solar wind (a stream of charged particles released from the sun) and sophisticated computer simulations. Research done at the University of New Hampshire has found that when choosing the right model to describe the solar wind, using the one that takes longer to calculate does not make it the most accurate.
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In the study, published in "Our research found that it makes a huge difference which model is used," said Verscharen. "We found that the much faster computed MHD models may actually capture some of the solar-wind behavior a lot better than expected. This is a very important result for solar-wind modelers because it may justify the application of MHD, based on first principles and observations."To prove his theory, Verscharen collected data taken from the WIND spacecraft, which is currently orbiting in the solar wind, from study co-authors Christopher Chen at the Imperial College London and Robert Wicks from University College London. After comparing the theory with the actual spacecraft data, the team found that the type of disturbance they were investigating behaved a lot more like a fluid than a kinetic medium with collisionless particles. This was unexpected because they believed that the kinetic theory should work much better in a gas as dilute, or thin, as the solar wind.The finding could lead to a more efficient way to forecast space weather for institutions that need to continually model the solar wind, like NASA. Severe space weather can cause satellite and communication failures, GPS loss, power outages, and can even have effects on commercial airlines and space flight. In order to forecast the effects that solar wind plasma and energetic particles might have on these systems, modelers currently run different computer simulations and compare the results. Verscharen and his team believe that their findings could help develop a set of criteria to determine which type of modeling would be most appropriate for their prediction efforts in specific situations."If the solar-wind parameters were a certain way, they could use MHD modeling and if not, they might be better to perform simulations based on kinetic theory," said Verscharen. "It would just provide a more efficient way to predict space weather and the solar wind."It is still not understood why the solar wind behaves like a fluid. The researchers hope future studies will determine under which conditions the solar wind can be modeled as a fluid with MHD, and when a kinetic model would be necessary.
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Weather
| 2,017 |
May 15, 2017
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https://www.sciencedaily.com/releases/2017/05/170515122204.htm
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Climate change: Extreme rainfall will vary between regions
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A new study by researchers from MIT and the Swiss Federal Institute of Technology in Zurich shows that the most extreme rain events in most regions of the world will increase in intensity by 3 to 15 percent, depending on region, for every degree Celsius that the planet warms.
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If global average temperatures rise by 4 degrees Celsius over the next hundred years, as many climate models predict given relatively high COThere are a few regions that are projected to experience a decrease in extreme rainfall as the world warms, mostly located over subtropical oceans that lie just outside the tropical, equatorial belt.The study, published in Paul O'Gorman, a co-author on the paper and associate professor of atmospheric science in MIT's Department of Earth, Atmospheric and Planetary Sciences, says being able to predict the severity of the strongest rain events, on a region-by-region basis, could help local planners prepare for potentially more devastating storms."There is interest around the world in the question of whether to adjust codes to adapt to a changing climate and precipitation, particularly for flooding," O'Gorman says. "We found there are regional variations in the projected precipitation response because of changes in winds, and of course if you're interested in the impacts of precipitation extremes, you'd want to know what's happening in your region."Since the 1990s, scientists have predicted based on climate models that the intensity of extreme rain events around the world should increase with rising global temperatures. Current observations have so far verified this trend on a broad, global scale. But knowing how extreme storms will change on a more specific, regional scale has been a trickier picture to resolve, as climate data is not equally available in all countries, or even continents, and the signal of climate change is masked by weather noise to a greater extent on the regional scale."The observations are telling us there will be increases [in extreme rainfall] at almost all latitudes, but if you want to know what's going to happen at the scale of a continent or smaller, it's a much more difficult question," O'Gorman says.He and his colleagues began their study by taking a global perspective. They first looked through a massive archive of global simulation runs, known as the Coupled Model Intercomparison Project Phase 5 (CMIP5), which aggregates outputs, or predictions, made by different climate models, for everything from local air pressure to the thickness of sea ice in response to changing climate.For this study, the researchers culled the CMIP5 archive for specific outputs, including daily accumulated surface precipitation and temperature, vertical wind velocity and pressure, and daily atmospheric humidity. These outputs were simulated by 22 climate models, for the years 1950 to 2100, under a scenario in which there are relatively high emissions of CO2.The team looked at each of the 22 models' outputs on a regional, grid-by-grid basis. Each model simulates climate conditions by dividing the globe up into a grid, with each grid cell's side measuring 100 to 200 kilometers. For each cell in each model, the researchers identified the maximum daily rainfall per year and compared this to the average global temperature for that year.All 22 models predicted that the highest increases in extreme rainfall will occur over parts of the Asian monsoon region such as India and over parts of the equatorial Pacific, with more moderate increases in North America, Central America, the Mediterranean, and Australia.O'Gorman says that while the spatial pattern of change was robust across the models, the magnitude of the change was much more uncertain in tropical regions, and higher-resolution modeling is needed to narrow down this uncertainty.To see what was influencing the region-to-region variability in rainfall increases, the team plugged the outputs into a physics-based formula that relates the amount of surface precipitation to the vertical winds and the amount of water vapor in the atmosphere. They found that, overall, it was the changes in winds, and not water vapor, that determined the region-to-region variations in the change in extreme rain intensity.The researchers also found decreases in extreme rainfall amounts over subtropical ocean regions, where the overlying atmosphere is generally dry, producing relatively weak storm systems."It's kind of striking," O'Gorman says. "Almost everywhere, there's an increase in precipitation extremes, except for these ocean regions."He suggests this may be partly due to the ongoing expansion of the tropics, and the associated changes to a atmospheric circulation system known as the Hadley cell, in which air rises near the equator and descends farther poleward. As the climate has warmed in past decades, researchers have noted that the climate at the equator has spread towards the poles, creating a much wider tropical belt. As the tropics and the Hadley cell continue to expand, this would affect the pattern of extreme precipitation, especially in the subtropics."The subtropics are generally dry, and if you move the region of descending air poleward, you would get some regions with increases, and others with decreases [in extreme rainfall]," O'Gorman says. "However we found that this only explained half of the decreases from changes in winds, so it's still something of a mystery as to why you get a decrease in precipitation extremes there."O'Gorman is currently investigating whether the duration of extreme rainfall events changes with increasing temperatures, which could have practical implications for determining the resilience of buildings and infrastructure."Given an extreme precipitation event, how long does it last, say in hours, and does that time change with climate warming?" O'Gorman says. "We think the intensity of an event changes, and if the duration also changes, that could be significant too."
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Weather
| 2,017 |
May 12, 2017
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https://www.sciencedaily.com/releases/2017/05/170512195738.htm
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Data science used to better predict effect of weather and other conditions
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In a new study, a team of researchers from Case Western Reserve University and Gebze Technical University (GTU) in Turkey used data science to determine and predict the effects of exposure to weather and other conditions on materials in solar panels.
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Using data science to predict the deterioration of such materials could lead to finding new ways to extend their lifetime, the researchers say."This makes the cost of solar energy -- in this case -- better and easier to understand," said Case Western Reserve Professor Laura Bruckman, who directed the study with Abdulkerim Gok, a research associate at GTU formerly with Case Western Reserve."If solar modules last 50 years, and science can back that up," she said, "it will make solar energy more affordable by decreasing the dollar-per-watt of electricity generation."The study, titled "Predictive models of poly (ethylene-terephthalate) film degradation under multi-factor accelerated weathering exposures," was published May 12 in the journal Their study combines engineering epidemiology and statistical-data analytics to develop predictive models for environmentally exposed applications.While the solar energy market continues to expand, the reliability and sustainability of solar energy systems remains a challenge. The stability of polymeric components is critical for the service lifetime of solar panels during outdoor use.PET (polyethylene terephthalate) -- what water bottles are made of -- is a common polymer. In solar panels, the polymer on the back of the module is an environmental barrier and protects people from getting an electrical shock if they touched a module.In the SDLE Research Center at Case Western Reserve, PET samples were exposed to various accelerated weathering conditions. Fixed- and mixed-effects modeling, under the guidance of Case Western Reserve Professor Jiayang Sun, in the Department of Epidemiology and Biostatistics, were used to predict degradation responses of different PET films.The journal article explains how comprehensive data-science methods were applied to a material-science degradation problem of PET films used as an environmental barrier in solar panels. The research explains the degradation of PET, which is necessary for lifetime prediction of solar panels.
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Weather
| 2,017 |
May 11, 2017
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https://www.sciencedaily.com/releases/2017/05/170511141956.htm
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Saying goodbye to glaciers
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Glaciers around the world are disappearing before our eyes, and the implications for people are wide-ranging and troubling, Twila Moon, a glacier expert at the University of Colorado Boulder, concludes in a Perspectives piece in the journal
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The melting of glacial ice contributes to sea-level rise, which threatens to "displace millions of people within the lifetime of many of today's children," Moon writes. Glaciers also serve up fresh water to communities around the world, are integral to the planet's weather and climate systems, and they are "unique landscapes for contemplation or exploration."And they're shrinking, fast, writes Moon, who returned to the National Snow and Ice Data Center this month after two years away. Her analysis, "Saying goodbye to glaciers," is published in the May 12 issue of Moon admits she was pretty giddy when an editor at But the topic, itself, is far from a happy one. Moon describes the many ways researchers study glacier dynamics, from in-place measurements on the ice to satellite-based monitoring campaigns to models. And she describes sobering trends: The projection that Switzerland will lose more than half of its small glaciers in the next 25 years; the substantial retreat of glaciers from the Antarctic, Patagonia, the Himalayas, Greenland and the Arctic; the disappearance of iconic glaciers in Glacier National Park, Montana, or reduction to chunks of ice that no longer move (by definition, a glacier must be massive enough to move).In her piece, Moon calls for continued diligence by the scientific community, where ice research is already becoming a priority.Moon says she got hooked on glaciers as an undergraduate in geological and environmental sciences at Stanford University, when she spent a semester abroad in Nepal. "For the first time I saw a big valley glacier, flowing through the Himalaya," she said, "and I thought it was about the coolest thing ever. After studying geology, the movement and sound of the ice, right now, made it feel almost alive.'"That experience kicked off a research career that has taken Moon to Greenland, Alaska, Norway, and to conferences around the world. She began her work "merely" as a geologist and glaciologist, interested in ice itself, Moon said. Only later did the influence of climate change come to play in her work."I think I'm about as young as you can get for being a person who started in glaciology at a time when climate change was not a primary part of the conversation," says Moon, who is 35.She is consistently sought out by journalists hoping to understand Earth's ice, and she's sought out in the scientific community as well, recognized as someone who likes to collaborate across disciplinary boundaries. She recently worked with a biologist in Washington, for example, on a paper about how narwhals use glacial fronts in summertime -- the tusked marine mammals appear to be attracted to glaciers with thick ice fronts and freshwater melt that's low in silt, though it's not yet clear why.After a couple of post-doctoral research years, at the National Snow and Ice Data Center and then the University of Oregon, Moon and her husband headed to Bristol, England, where she took a faculty position at the University of Bristol's School of Geographical Sciences. When it became clear that her husband's work wouldn't transfer, the two determined to head back to the Rocky Mountains.Moon started back as a researcher at CU Boulder's National Snow and Ice Data Center, part of CIRES, May 1.
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Weather
| 2,017 |
May 10, 2017
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https://www.sciencedaily.com/releases/2017/05/170510095641.htm
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As heat index climbs, emergency visits, deaths rise in New England
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Better known for leaf peeping on crisp autumn days and the nor'easter blizzards that follow, New England is nevertheless subject to spells of punishing summer heat and humidity. A new study that analyzed the health effects of summer weather in small to midsize population centers in three states shows that deaths and emergency department visits begin to rise significantly across the region well before the heat index hits the triple digits.
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Data from the study, published in Environmental Research, has helped to shape a new National Weather Service policy for the New England region, according to a recently posted statement from the service's eastern region headquarters."The old threshold of 100 to 104 degrees Farenheit for two or more consecutive hours has been lowered to 95 to 99 degrees Farenheit occurring for two or more consecutive days, or any duration of heat index 100 to 104 degrees Farenheit," the statement says.Heat index is a measure that combines temperature and humidity to express what the heat actually feels like. An 86-degree day with 70 percent humidity, for example, is enough to produce a heat index of 95.In the new analysis, researchers at Brown University and the state health departments of Maine, New Hampshire and Rhode Island found that compared to days with a comfortable heat index of 75, days with a heat index of 95 resulted in 7.5 percent more heat-related emergency department visits and 5.1 percent more heat-related deaths over the following week. In absolute numbers, the health impact of all days with a heat index of at least 95 degrees among the 2.7 million residents in the study area was 784 additional emergency department visits per year and 22 more deaths per year attributable to heat."This hasn't been looked at in New England specifically, and New England has a very different set of characteristics and population than some other parts of the country," said study lead author Gregory Wellenius, an associate professor of epidemiology at the Brown University School of Public Health. "We provided local evidence to local policy makers, and they have acted to improve the heat warning system in the area."Many prior studies have shown the health dangers of excessive heat in the U.S. and around the world, Wellenius said, but the impetus for the new study was a desire among state health officials for data specific to the region. Geographically, much of New England is characterized by small towns and midsize communities embedded within open areas, rather than densely urban or entirely rural landscapes. Meanwhile, the population is less acclimated to stretches of extreme heat than areas further south. For example, the region has a notably lower adoption and use of air conditioning than the rest of the Northeast or the U.S. as a whole"People often think that in New England or in cooler climates, heat isn't as big a threat because it doesn't get that hot, or get that hot very often, but in fact it still feels hot to the people here," Wellenius said.To conduct the study, the team focused on the populations living within 10 miles of 14 National Weather Service stations in New Hampshire and Maine and on the entirety of Rhode Island. Looking at datasets mostly spanning the period 2000 to 2010, they combined May-to-September weather information from each station with health, death and demographic data from state health departments.Statistically controlling for possible confounders such as day of the week and federal holidays, the researchers calculated the association between daily heat index and the number of heat-related emergency visits and deaths, as designated in state administrative records.Compared to a "baseline" of days with a 75-degree heat index, emergency visits climbed with statistical significance starting with 80-degree heat index days, especially when researchers considered visits occurring during the full week following such hotter days. Visits rose 2 percent following an 80-degree heat index day, 4 percent after 85, 5.8 percent after 90, 7.5 percent after 95, 9.1 percent after 100, and 10.7 percent after 105.Excess deaths followed a similar pattern of increasing relative risk, though with thankfully fewer absolute numbers, measures of statistical significance did not emerge until the heat index soared higher. At a heat index of 95, deaths were 5.1 percent higher, at 100 they were 9.4 percent higher, and at 105 they were 14.4 percent higher.Wellenius said it is worth noting that emergency visits in particular continue to rise for days after an elevated heat index event."Much of the burden on health is on a day other than the same day," he said. "This is not something that is part of our health response plans right now."Wellenius said he hopes the study and the related National Weather Service policy change will help New Englanders better understand the health risks of heat and motivate them to take steps to protect themselves and others. In future research, he said, he and collaborators would like to track the impact heat warnings and other public response measures have on reducing emergency visits and deaths."How many lives are these efforts actually saving?" he asked.Another question is how climate change might exacerbate the situation."Under the temperatures projected through the end of the century, New England is going to see large increases in the number of days where we exceed 90, 95 or 100 degrees of heat index," he said.
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Weather
| 2,017 |
May 9, 2017
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https://www.sciencedaily.com/releases/2017/05/170509083829.htm
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Power plants could cut a third of their emissions by using solar energy
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Led by VTT Technical Research Centre of Finland, the COMBO-CFB project has developed a new innovative concept to increase solar energy production in the energy system. According to this research, the concept can reduce fuel consumption and emissions stressing the climate by more than 33 per cent. The concept is based on the combination of concentrated solar power (CSP) technology and a traditional power plant process into a hybrid plant which produces electricity on the basis of consumption.
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If part of the fuel used by a power plant is replaced with solar energy, power plant emissions will be reduced. This is also required in order to meet the emission reduction targets. The COMBO-CFB project − Combination of concentrated solar power (CSP) with circulating fluidized bed (CFB) power plants − examined how various types of hybrid plant solutions can produce power flexibly according to demand, without the need for energy storage. The project analysed and compared different hybrid plant concepts.The concept in which steam generated by a solar field was fed directly into the power plant's high-pressure turbine brought a reduction in emissions and fuel consumption which, at best, exceeded 33 per cent. Furthermore, a reasonable dimensioning of the hybrid plant and process optimisation can bring efficiency benefits as compared to the use of separate power production methods. In the aforementioned case, the plant's net efficiency improved by 0.8 per cent. In addition to positive climate effects, good hybrid plant planning can also bring financial benefits since part of the power plant components are shared by two power production methods.The COMBO-CFB project applied the Finnish project partners' high-level expertise in boiler technology. In a hybrid power plant, solar energy production which varies with weather is balanced by using a steam boiler. The production concepts developed through this project will expand the application possibilities of the CSP technology.The dynamic nature of a hybrid process poses challenges to production system design and operation, particularly when the share of solar energy in power production is high. The COMBO-CFB project examined these challenges by using the Apros software designed for dynamic modelling, as well as through combustion tests conducted by using VTT's pilot equipment in Jyväskylä, Finland. This dynamic assessment at the plant design stage proved extremely important since it enables designers to take account of factors such as those affecting the lifetime of components.The concept in which part of the feedwater preheating is substituted with solar steam can be implemented in the present power plants, but compared to the aforementioned high-pressure turbine concept, the benefits are considerably smaller due to the smaller share of solar energy. The functioning of a hybrid process can be generally improved by attaching to it an advanced predictive control system and a short-term solar irradiance forecast. In the COMBO-CFB project, Vaisala developed a cloud camera which identifies cloud movements in the sky in order to increase the accuracy of the solar irradiance forecast for the area.The implementation of the CSP technology in power production is reasonable in areas with an abundance of sunlight. In Europe, this means, for example, the countries bordering the Mediterranean. However, this technology can also be implemented in areas with less sunlight by using hybrid power plants in which solar power is supported by another form of energy. For the time being, Finland is not applying this technology, whereas Denmark is already using a CSP-bio hybrid plant to produce district heating.Finland has unique, internationally competitive expertise that it can provide to the hybrid power plant export markets. The COMBO-CFB project's partner network can support the commercialisation of such hybrid plants. The Finnish project partners' areas of expertise include boiler and control technology, process modelling and weather measurement and forecasting.
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Weather
| 2,017 |
May 8, 2017
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https://www.sciencedaily.com/releases/2017/05/170508083716.htm
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Scottish badgers highlight the complexity of species responses to environmental change
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In a new study researchers have found that although warmer weather should benefit badger populations, the predicted human population increase in the Scottish highlands is likely to disturb badgers and counteract that effect. These results emphasise the importance of interactive effects and context-dependent responses when planning conservation management under human-induced rapid environmental change.
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The new findings, published in the scientific journal Diversity and Distributions, result from a collaboration between researchers from Uppsala University in Sweden and Oxford's Wildlife Conservation Research Unit. Building on data from 168 camera trap stations actually collected originally to look at Scottish wildcat distributions, the team was also able to detect local badger (Meles meles) presence and absence. They found that different factors, such as weather conditions, land cover type and human disturbance interact to determine which locations badgers choose to populate across the Scottish Highlands.Overall, badger occupancy was more likely at sites with higher minimum winter temperature and lower elevation. But when study areas of similar temperature and elevation were grouped together, more complex patterns emerged. Specifically, in less favourable cooler upland areas badger occupancy was associated with higher availability of agricultural patches, possibly due to the additional food resources they provide. This pattern was, however, not found in warmer lowland areas. These lowland areas typically provide more favourable foraging conditions, but also include more human infrastructures (farms, roads, villages, etc) that constrained badger occurrence; badgers were more often found further away from settlements and roads.While medium estimates of a 1-3°C increase in mean minimum winter temperature for Northern Scotland by the 2050s would lead to better conditions for badgers in Highland Scotland, forecasts based on this factor alone are likely to prove simplistic and naïve. Disturbances associated with a predicted parallel 5% increase in human population in the Scottish Highlands by 2037 may counteract the benefits of increasing temperatures.It may therefore prove faulty or superficial to assume that species will simply benefit from warming conditions along the former cold-edge of their distribution if other environmental factors are not considered.The study was led by André Silva and Gonçalo Curveira-Santos from Uppsala University and University of Lisbon, in collaboration with WildCRU (Oxford University) and the University of Aveiro.
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Weather
| 2,017 |
May 3, 2017
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https://www.sciencedaily.com/releases/2017/05/170503092206.htm
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Keeping cool in the summer leads to increased air pollution
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As the weather warms, so does the use of air conditioners. But running these devices requires power plants to ratchet up electricity production, causing air polluting emissions to rise. An analysis of 27 states found that, on average, summer emissions of sulfur dioxide (SO
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A large body of research has investigated the influence of weather and climate on atmospheric chemistry. But few studies have examined the specific effects of climate on electricity emissions and air quality. Although overall emissions have dropped due to pollution control devices and a drop in coal use, regional and seasonal increases in power plant pollution could affect people's health and the environment. SOUsing data collected between 2003 and 2014, the researchers crunched the numbers on electricity emissions in 27 states, mostly in the Eastern U.S. From this analysis, they observed that power plants released 3.35 percent more SO
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Weather
| 2,017 |
May 2, 2017
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https://www.sciencedaily.com/releases/2017/05/170502084037.htm
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Antarctic Peninsula ice more stable than thought
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Glacier flow at the southern Antarctic Peninsula has increased since the 1990s, but a new study has found the change to be only a third of what was recently reported.
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An international team of researchers, led by the UK Centre for Polar Observation and Modelling at the University of Leeds, are the first to map the change in ice speed. The team collated measurements recorded by five different satellites to track changes in the speed of more than 30 glaciers since 1992.The findings, published today in The new Leeds led research calls into question a recent study from the University of Bristol that reported 45 cubic kilometres per year increase in ice loss from the sector. The Leeds research found the increase to be three times smaller.Lead author Dr Anna Hogg, from the Leeds' School of Earth and Environment, said: "Dramatic changes have been reported in this part of Antarctica, so we took a closer look at how its glaciers have evolved using 25 years of satellite measurements dating back to the early 1990s."The researchers found that between 1992 and 2016, the flow of most of the region's glaciers increased by between 20 and 30 centimetres per day, equating to an average 13% speedup across the glaciers of Western Palmer Land as a whole.These measurements provide the first direct evidence that Western Palmer Land is losing ice due to increased glacier flow -- a process known as dynamical imbalance.The team also combined their satellite observations with an ice flow model using data assimilation to fill in gaps where the satellites were unable to produce measurements. This allowed the complete pattern of ice flow to be mapped, revealing that the regions glaciers are now pouring an additional 15 cubic kilometres of ice into the oceans each year compared to the 1990s.The earlier study reported that the region was losing three times this amount of ice, based on measurements of glacier thinning and mass loss determined from other satellite measurements. The Leeds study casts doubt on that interpretation, because the degree of glacier speedup is far too small.Study co-author Professor Andrew Shepherd, from Leeds' School of Earth and Environment, explained: "Although Western Palmer Land holds a lot of ice -- enough to raise global sea levels by 20 centimetres -- its glaciers can't be responsible for a major contribution to sea level rise, because their speed has barely changed over the past 25 years. It's possible that it has snowed less in this part of Antarctica in recent years -- that would also cause the glaciers to thin and lose mass, but it's a not a signal of dynamical imbalance."The greatest speedup in flow was observed at glaciers that were grounded at depths more than 300 m below the ocean surface.Dr Hogg said: "We looked at water temperatures in front of the glaciers which have sped up the most, and we found that they flow through deep bedrock channels into the warmest layer of the ocean. This circumpolar deep water, which is relatively warm and salty compared to other parts of the Southern Ocean, has warmed and shoaled in recent decades, and can melt ice at the base of glaciers which reduces friction and allows them to flow more freely.With much of Western Palmer Land's ice mass lying well below sea level it is important to monitor how remote areas such as this, are responding to climate change. Satellites are the perfect tool to do this.Pierre Potin, ESA's Manager of the Copernicus Sentinel-1 Mission which was used in the study, said: "We will continue to use Sentinel-1's all weather, day-night imaging capability to extend the long term climate data record from European satellites."
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Weather
| 2,017 |
May 1, 2017
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https://www.sciencedaily.com/releases/2017/05/170501131749.htm
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Researchers develop radar simulator to characterize scattering of debris in tornadoes
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Researchers have developed the first numerical polarimetric radar simulator to study and characterize the scattering of debris particles in tornadoes.
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The results of their study are published in the Institute of Electrical and Electronics Engineers (IEEE) journal "These results are important for operational weather forecasters and emergency managers," says Nick Anderson, program director in the National Science Foundation's (NSF) Division of Atmospheric and Geospace Sciences, which funded the research. "An improved understanding of what weather radars tell us about tornado debris can help provide more accurate tornado warnings and quickly direct emergency personnel to affected areas."Current polarimetric radars, also called dual-polarization radars, transmit radio wave pulses horizontally and vertically. The pulses measure the horizontal and vertical dimensions of precipitation particles.The radars provide estimates of rain and snow rates, accurate identification of the regions where rain transitions to snow during winter storms, and detection of large hail in summer thunderstorms.But polarimetric radars have limitations the new research aims to address."With this simulator, we can explain in great detail to the operational weather community [weather forecasters] the tornadic echo from polarimetric radar," says Robert Palmer, an atmospheric scientist at the University of Oklahoma (OU) and co-author of the paper. Palmer is also director of the university's Advanced Radar Research Center. "The knowledge gained from this study will improve tornado detection and near real-time damage estimates."Characterizing debris fields in tornadoes is vital, scientists say, because flying debris causes most tornado fatalities.The researchers conducted controlled measurements of tornado debris to determine the scattering characteristics of several debris types, such as leaves, shingles and boards. The orientation of the debris, the scientists found, makes a difference in how it scatters and falls through the atmosphere -- and where it lands.
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Weather
| 2,017 |
May 1, 2017
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https://www.sciencedaily.com/releases/2017/05/170501102241.htm
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SimRadar: A polarimetric radar time-series simulator for tornadic debris studies
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A University of Oklahoma research team with the Advanced Radar Research Center has developed the first numerical polarimetric radar simulator to study and characterize scattering mechanisms of debris particles in tornadoes. Characterizing the debris field of a tornado is vital given flying debris cause most tornado fatalities. Tornado debris characteristics are poorly understood even though the upgrade of the nation's radar network to dual polarimetric radar offers potentially valuable capabilities for improving tornado warnings and nowcasting.
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"These results are important for operational weather forecasters and emergency managers," says Nick Anderson, program director in the National Science Foundation Division of Atmospheric and Geospace Sciences, which funded the research. "An improved understanding of what weather radars tell us about tornado debris can help provide more accurate tornado warnings, and quickly direct emergency personnel to affected areas.""With this simulator, we can explain in great detail to the operational weather community the tornadic echo from the polarimetric radar," said Robert Palmer, ARRC executive director. "The signal received by the dual polarimetric radar is not easily understood because rain is mixed with the debris. The knowledge we gain from this study will improve tornado detection and near real-time damage estimation."Numerous controlled anechoic chamber measurements of tornadic debris were conducted at the Radar Innovations Laboratory on the OU Research Campus to determine the scattering characteristics of several debris types -- leaves, shingles and boards. Palmer, D.J. Bodine, B.L.Cheong, C.J. Fulton and S.M. Torres, the center, and the OU Schools of Electrical and Computer Engineering and Meteorology, developed the simulator to provide comparisons for actual polarimetric radar measurements.Before this study, there were many unanswered questions related to tornado debris scattering, such as knowing how the size, concentration and shape of different debris types affect polarimetric variables. How the radar identifies the debris is equally as important. Orientation of debris makes a difference as well as how the debris falls through the atmosphere. Overall, understanding debris scattering characteristics aid in the discovery of the relationship between debris characteristics, such as lofting and centrifuging, and tornado dynamics.OU team members were responsible for various aspects of this study. Coordination of damage surveys and collection of debris samples were led by Bodine. Field experiments were designed by team members in collaboration with Howard Bluestein, OU School of Meteorology. Electromagnetic simulations and anechoic chamber experiments were led by Fulton. The signal processing algorithms were developed by Torres and his team. Cheong led the simulation development team.
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Weather
| 2,017 |
April 28, 2017
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https://www.sciencedaily.com/releases/2017/04/170428093912.htm
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Weather extremes and trade policies were main drivers of wheat price peaks
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Price peaks of wheat on the world market are mainly caused by production shocks such as induced for example by droughts, researchers found. These shocks get exacerbated by low storage levels as well as protective trade policies, the analysis of global data deriving from the US Department of Agriculture shows. In contrast to widespread assumptions, neither speculation across stock or commodity markets nor land-use for biofuel production were decisive for annual wheat price changes in the past four decades. This finding allows for better risk assessment. Soaring global crop prices in some years can contribute to local food crises, and climate change from burning fossil fuels and emitting greenhouse gases is increasing weather variability.
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"Food security to a large extent is a matter of prices, hence our interest in understanding what drives variations from one year to another," says lead-author Jacob Schewe from the Potsdam Institute for Climate Impact Research (PIK).When global wheat prices, along with those of other staple crops, skyrocketed in 2007/08 and again in 2010/11, poor people in many developing countries suffered from that -- these temporary price rises have even been linked to food riots in several countries. "These recent peaks, as others, have been preceded by severe droughts that reduced crop production. Now we can show that such weather-induced shocks have the potential to induce strong price increases," says Schewe "Moreover, they can trigger protective trade policy responses, including hoarding or export bans, which further exacerbate the global effects of production shortfalls even though they may seem rational from a country's point of view. This happened during the recent price peaks.""While cross-market speculation might further exacerbate the problem on monthly or shorter time-scales, the data indicate that in the end it was a minor factor for annual prices," adds co-author Christian Otto. This is despite the fact that the sudden price increase in 2007/08 coincides with speculation by index funds driven out of the collapsing US housing and stock markets.The researchers developed and applied a rather simple computer simulation of wheat markets. By comparing the results to observation data from past years, the scientists checked that the computer simulations fit reality. Importantly, the factor of supply and demand from storage -- also based on existing data from markets -- is integrated in these calculations. The simulation model could be applied for assessments of future wheat price fluctuations under climate and land use changes."The good news: Our study helps to understand what can be done if we want to limit food price peaks in the future," says Katja Frieler, co-author of the study and vice-chair of PIK's research domain Climate Impacts and Vulnerabilities. "First, besides improving productivity experts can seek to carefully adjust trade policies as well as storage capacities. Second, stabilizing the climate by reducing greenhouse gas emissions is key if we want to limit the risks of weather extremes across the globe."
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April 26, 2017
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https://www.sciencedaily.com/releases/2017/04/170426121757.htm
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Wind, rain play key role in breeding patterns of migratory tree swallows
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Wind and precipitation play a crucial role in advancing or delaying the breeding cycles of North American tree swallows, according to the results of a new University of Colorado Boulder-led study.
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The research, which appears in the journal Over the past decade and a half, the average egg hatching date for tree swallows -- a common migratory bird species that winters in temperate southern climates before nesting in the spring at sites across North America, including the sub-Arctic regions covered in the study -- has shifted earlier in the year by an average of six days. This change is similar to, but considerably greater than, changes seen in more southerly sites and until now has been believed to correlate with rising temperatures.However, when CU Boulder researchers tested how swallow nesting data from two different Alaskan sites corresponded with both daily and seasonal climate indicators like the number of windy days, days with measureable precipitation and average daily temperature, they found that windiness (or lack thereof) had the most consistent correlation with swallow breeding patterns over time."We expected that temperature and precipitation would be much more strongly predictive than wind," said Daniel Doak, a professor in CU Boulder's Environmental Studies Program and the co-author of the new research. "The study demonstrates that fine-scale climate effects are important to consider when thinking about what's going to affect a species."The study developed as a result of a CU Boulder undergraduate's research efforts. Rachel Irons, then a junior in the Department of Ecology and Evolutionary Biology, received a UROP grant and worked with the Alaska Department of Fish and Game on a long-term tree swallow nesting study to fulfill her senior thesis requirements."Swallow phenology in Alaska is shifting at twice the rate of the continental U.S.," said Irons, who is the lead author of the new paper. "I figured it was related to temperature, but I added in wind and precipitation measurements just to get the whole climate picture."The results showed that a long-term decline in windiness (and to a more variable extent, rain) in central Alaska over the past decade-plus correlated with the birds' earlier breeding much more strongly than temperature, indicating that wet, windy spring weather that may have delayed egg laying in the past is now less of an impediment for the swallows.The authors noted that while it is not necessarily surprising that wind and rain would affect an aerial foraging species like tree swallows, the findings emphasize the need to broaden the scope of consideration when making predictions about which climate mechanisms will influence population ecology."This shows that our initial intuitions are not always good about what's going to impact these birds and their patterns," said Doak.
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April 25, 2017
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https://www.sciencedaily.com/releases/2017/04/170425182132.htm
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Is climate change responsible for record-setting extreme weather events?
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After an unusually intense heat wave, downpour or drought, Noah Diffenbaugh and his research group inevitably receive phone calls and emails asking whether human-caused climate change played a role.
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"The question is being asked by the general public and by people trying to make decisions about how to manage the risks of a changing climate," said Diffenbaugh, a professor of Earth system science at Stanford's School of Earth, Energy & Environmental Sciences. "Getting an accurate answer is important for everything from farming to insurance premiums, to international supply chains, to infrastructure planning."In the past, scientists typically avoided linking individual weather events to climate change, citing the challenges of teasing apart human influence from the natural variability of the weather. But that is changing."Over the past decade, there's been an explosion of research, to the point that we are seeing results released within a few weeks of a major event," said Diffenbaugh, who is also the Kimmelman Family Senior Fellow at the Stanford Woods Institute for the Environment.In a new study, published in this week's issue of In order to avoid inappropriately attributing an event to climate change, the authors began with the assumption that global warming had played no role, and then used statistical analyses to test whether that assumption was valid. "Our approach is very conservative," Diffenbaugh said. "It's like the presumption of innocence in our legal system: The default is that the weather event was just bad luck, and a really high burden of proof is required to assign blame to global warming."The authors applied their framework to the hottest, wettest and driest events that have occurred in different areas of the world. They found that global warming from human emissions of greenhouse gases has increased the odds of the hottest events across more than 80 percent of the surface area of the globe for which observations were available. "Our results suggest that the world isn't quite at the point where every record hot event has a detectable human fingerprint, but we are getting close," Diffenbaugh said.For the driest and wettest events, the authors found that human influence on the atmosphere has increased the odds across approximately half of the area that has reliable observations. "Precipitation is inherently noisier than temperature, so we expect the signal to be less clear," Diffenbaugh said. "One of the clearest signals that we do see is an increase in the odds of extreme dry events in the tropics. This is also where we see the biggest increase in the odds of protracted hot events -- a combination that poses real risks for vulnerable communities and ecosystems."The Stanford research team, which includes a number of former students and postdocs who have moved on to positions at other universities, has been developing the extreme event framework in recent years, focusing on individual events such as the 2012-2017 California drought and the catastrophic flooding in northern India in June 2013. In the new study, a major goal was to test the ability of the framework to evaluate events in multiple regions of the world, and to extend beyond extreme temperature and precipitation, which have been the emphasis of most event attribution studies.One high-profile test case was Arctic sea ice, which has declined by around 40 percent during the summer season over the past three decades. When the team members applied their framework to the record-low Arctic sea ice cover observed in September 2012, they found overwhelming statistical evidence that global warming contributed to the severity and probability of the 2012 sea ice measurements. "The trend in the Arctic has been really steep, and our results show that it would have been extremely unlikely to achieve the record-low sea ice extent without global warming," Diffenbaugh said.Another strength of a multi-pronged approach, the team said, is that it can be used to study not only the weather conditions at the surface, but also the meteorological "ingredients" that contribute to rare events. "For example, we found that the atmospheric pressure pattern that occurred over Russia during the 2010 heat wave has become more likely in recent decades, and that global warming has contributed to those odds," said co-author Daniel Horton, an assistant professor at Northwestern University in Evanston, Illinois, and a former postdoc in Diffenbaugh's lab who has led research on the influence of atmospheric pressure patterns on surface temperature extremes. "If the odds of an individual ingredient are changing -- like the pressure patterns that lead to heat waves -- that puts a thumb on the scales for the extreme event."Diffenbaugh sees the demand for rigorous, quantitative event attribution growing in the coming years. "When you look at the historical data, there's no question that global warming is happening and that extremes are increasing in many areas of the world," he said. "People make a lot of decisions -- short term and long term -- that depend on the weather, so it makes sense that they want to know whether global warming is making record-breaking events more likely. As scientists, we want to make sure that they have accurate, objective, transparent information to work with when they make those decisions."
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April 25, 2017
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https://www.sciencedaily.com/releases/2017/04/170425162211.htm
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Cold weather linked to mortality risks in Texas, research shows
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Cold weather increases the risk of mortality in Texas residents, according to researchers at The University of Texas Health Science Center at Houston (UTHealth) School of Public Health. The findings were recently published in the journal
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In the state's 12 major metro areas from 1990 to 2011, researchers found that cold temperatures significantly increased the risk of mortality by up to 5 percent with a 1 degree Celsius decrease in temperature in the winter. A 1-degree Celsius drop caused a combined 166 excessive deaths, researchers found. Higher mortality risks were observed in areas with higher winter temperatures and lower latitudes. For the metropolitan areas along the Gulf Coast, increased risk in mortality ranged from 2 to 5 percent."Cold weather can trigger certain diseases and even death because it can put extra strain on body systems such as the thermoregulation, heart and circulatory systems. With changing temperatures, your body has to adjust to maintain a stable body temperature," said senior author Kai Zhang, Ph.D., assistant professor in the Department of Epidemiology, Human Genetics and Environmental Sciences.According to the Centers for Disease Control and Prevention, from 2006 to 2010, about 2,000 people in the United States died each year due to weather-related causes. Of those deaths, 63 percent were attributed to exposure to excessive natural cold, hypothermia or both.Zhang said, however, "The CDC's estimate is significantly underestimated because cold weather can affect people with pre-existing diseases, resulting in the attribution of primary cause of death to these diseases rather than to cold weather."The study focused on the effects of cold weather in 12 metropolitan areas with a population of more than 200,000 across Texas: Austin-Round Rock, Beaumont-Port Arthur, Brownsville-Harlingen, Corpus Christi, Dallas-Fort Worth-Arlington, El Paso, Houston-The Woodlands-Sugar Land, Killeen-Temple, Lubbock, McAllen-Edinburg-Mission, San Antonio-New Braunfels and Waco.Researchers also estimated the effects of cold waves, which are extended periods of extremely cold temperatures. They observed the highest impact of cold waves in areas along the Gulf Coast, which had increased risks ranging from 3 to 8 percent depending on the area.According to the researchers, cold temperatures affected those 75 and older most and at an even higher rate because of the vulnerability of their body systems to cold temperatures.Researchers also found that in Texas, cold weather significantly increases mortality risk highest in people who have suffered from a heart attack or have pre-existing conditions like respiratory disease, ischemic heart disease and cardiovascular disease.The highest increased risk for these diseases across Texas was observed in Brownsville/Harlingen, one of the southernmost metropolitan areas in Texas."For those with existing heart and respiratory disease, they have to deal with additional pressure and thus are vulnerable to cold weather," Zhang said. "These findings highlight the significant impact of cold weather on mortality in Texas and support the importance of prevention and interventions to reduce adverse health effects, particularly among vulnerable populations."
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Weather
| 2,017 |
April 25, 2017
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https://www.sciencedaily.com/releases/2017/04/170425092301.htm
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Warm winds: New insight into what weakens Antarctic ice shelves
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New research describes for the first time the role that warm, dry winds play in influencing the behaviour of Antarctic ice shelves. Presenting this week at a European conference scientists from British Antarctic Survey (BAS) explain how spring and summer winds, known as föhn winds, are prevalent on the Larsen C Ice Shelf, West Antarctica and creating melt pools. The Larsen C Ice Shelf is of particular interest to scientists because it of the collapse of Larsen A in 1995 and Larsen B in 2002.
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The researchers observed the föhn winds, which blow around 65% of the spring and summer period, extend further south and are more frequent than previously thought, and are likely to be a contributing factor that weakens ice shelves before a collapse. The results are presented this week at the European Geosciences Union General Assembly (EGU) in Vienna.In 1995 and 2002, the Larsen A and B ice shelves collapsed, depositing an area the size of Shropshire into the Weddell Sea. Whilst ice shelf collapse doesn't directly contribute to sea level rise, the glaciers which fed into the ice shelves accelerated, leading to the loss of land ice, and subsequently indirect sea level rise. The processes responsible for the collapse of these ice shelves were largely debated, and it is now thought that crevasses on the ice shelf were widened and deepened by water draining into the cracks. Föhn winds are thought to be responsible for melting the ice shelf surface and supplying the water.The findings describe when and where the warm, dry winds occur over the Larsen C Ice Shelf, the largest remaining ice shelf on the Antarctic Peninsula (roughly the size of Wales). Föhn winds were measured from near-surface weather stations and regional climate model data over a five year period and observed all year-round, but were most frequent in spring.PhD student and lead scientist on this project from British Antarctic Survey (BAS) and Leeds University, Jenny Turton says, "What's new and surprising from this study is that föhn winds occur around 65% of the time during the spring and summer. And we didn't know how much they influence the creation of melt pools and therefore are likely to weaken the ice shelf. Whilst a high number occur in spring, the combined warming over a number of days leads to much more surface melting than was experienced during days without föhn winds. This is important, as melting during summer and re-freezing during winter weakens the ice surface, and makes it more at risk of melting again the following season."We know the ice shelf often melts a little during summer, however we have found that when föhn events occur as early as September (three months earlier than the start of the summer melt season), the ice shelf surface is melting. Now that we know how prevalent and spatially extensive these winds are, we can look further into the effect they are having on the ice shelf."
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Weather
| 2,017 |
April 25, 2017
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https://www.sciencedaily.com/releases/2017/04/170425092245.htm
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Predicting the movement, impacts of microplastic pollution
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Marine circulation and weather conditions greatly affect microplastic aggregation and movement. Microplastics, which are particles measuring less than 5 mm, are of increasing concern. They not only become more relevant as other plastic marine litter breaks down into tiny particles, they also interact with species in a range of marine habitats. A study by Natalie Welden and Amy Lusher published in
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Natalie Welden of Open University and lead author of the paper notes, "The ability to predict areas of plastic input and deposition would enable the identification of at risk species, and it would allow for efforts to reduce and remove plastic debris at targeted locations. The current uncertainty as to the effects of global warming on our oceans is the greatest challenge in predicting the future patterns of plastic aggregation in relation to global circulation."Littering, landfill runoff and loss at sea are the main pathways through which plastics enter the ocean. It is estimated that plastic waste from coastal countries will increase nearly 20-fold by 2025. The density of the plastic determines if it remains in surface waters, becomes beached in coastal areas and estuaries, or sinks to deep-sea sediments. Further, weather conditions and marine circulation play a significant role in the distribution. For example, the circular systems of ocean currents, such as the Gulf Stream in the North Atlantic or the California Current in the Pacific, play a significant role in the movement of plastics from their point of release to remote areas where they can accumulate in central ocean regions called gyres. Unusual large amounts of marine debris have been found in these zones, such as the North Atlantic or Great Pacific garbage patches.However, our oceans are currently undergoing a marked period of uncertainty brought about by global climate change. For example, ice melts in polar regions is predicted to have a range of effects on the distribution on marine plastics. As many swimmers know, it is easier to float in saltwater than a swimming pool. Reduction in the density of seawater at sites of freshwater input is expected to reduce the relative buoyancy of marine debris, increasing the rate at which plastics sink. Correspondingly, areas of high evaporation, due to the increase in temperature, will experience increased water densities, resulting in plastics persisting in the water column and surface waters.Adding another layer of complexity, changes in sea surface temperature may also affect the scale and patterns of precipitation, in particular tropical storms, cyclones and tornadoes. Global warming intensifies along-shore wind stress on the ocean surface. Flooding events, intense storms and increasing sea levels also means that more debris littering shorelines will become available for transport in the seas."The hope is that future models of climate-ocean feedback are producing more accurate predictions of circulation patterns," said Welden. "This is vital in forecasting and mitigating potential microplastic hotspots and 'garbage patches'."
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Weather
| 2,017 |
April 24, 2017
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https://www.sciencedaily.com/releases/2017/04/170424172212.htm
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Geologist discovers whirlwind phenomena in Andes mountains
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There's a lot to be learned from the winds in a Chilean desert-everything from surviving tornadoes on Earth to planning travel to Mars, with surviving climate change in between. And it took West Virginia University geologist Kathleen Benison to find it.
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In 2007, Benison discovered an anomaly in saline lakes in the Chilean Andes and her subsequent work disproved the conventional wisdom that gravel was too big to be affected significantly by wind. Her work can help explain historic weather patterns on Earth and even help prepare for a trip to Mars, which is whipped by whirlwinds.With changing environments due to global warming, conditions are becoming more extreme due to higher energy in the atmosphere. Deserts are expected to become drier and windier, and stronger and bigger dust devils (such as the Chilean gravel devils) may form.Much of the world's human population lives in and near deserts, so these changes could impact them. In addition, tornadoes seem to be getting more frequent and impacting a larger region with global warming. Even though gravel devils form on sunny days and tornadoes are spawn from thunderstorms, they have similar rotation, and both can be quite destructive. Understanding the gravel devils can help develop better plans, such as with building materials and designs, to limit destruction by tornadoes.
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Weather
| 2,017 |
April 24, 2017
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https://www.sciencedaily.com/releases/2017/04/170424093940.htm
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Ambulances respond more slowly in summer and winter
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Ambulance response times in London worsen when air temperatures rise or fall beyond certain limits in summer and winter, according to a new study.
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Services are vulnerable to disruptions from both hot and cold weather, with the speed of ambulance response beginning to suffer when the mean daily air temperature drops below 2°C or rises above 20°C. This is thanks, largely, to more emergency calls past these thresholds.Researchers at the University of Birmingham recommend that bespoke weather forecasts are built into ambulance service prediction models. This would allow managers to better predict call-out rates to improve ambulance operations and also reduce air pollution from idling vehicles on urban streets.Current daily estimates at the London Ambulance Service (LAS) of vehicles likely to be required in the week ahead are based on statistics for the same days of the year over the last three years. However, the weather is rarely the same on a particular day, or week, from year to year.Researchers in the University's Ambulance Atmospheric Impact Research' team (AAIR) produced the study, which is being presented at the General Assembly of the European Geosciences Union, in Vienna.Lead author Dr Francis Pope, from the University of Birmingham's School of Geography, Earth and Environmental Sciences, said: "The weather impacts directly on day-to-day ambulance operations, whilst the climate contributes to the number of staff and vehicles required."We recommend further research to allow ambulance planners to incorporate bespoke weather forecasts into planning systems, as there is evidence that heatwaves and coldwaves could increasingly cause increased demand and ambulance response time delays."Ambulance services operate 24 hours-a-day around most of the world. In England, more than nine million emergency calls were received in 2014/15. The study shows that response times worsen more rapidly at lower temperatures because of ice and snow on the roads.The LAS uses the Advanced Medical Priority Dispatch System (AMPDS) to assess the patient's main complaint or injury. Life threatening complaints have a target response time of eight minutes or less and 75% of these 'Category A' complaint types must be answered within the target time.Research shows that, as the temperature drops below 2°C or rises above 20°C, the total ambulance call-out volume increases and the percentage of responses within the eight-minute target time reduces.A 20% increase in daily call-outs, compared to the average, leads to a decrease in performance (% response in eight minutes) of 14.4% and 8.2% for temperatures below 2°C or above 20°C.
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Weather
| 2,017 |
April 20, 2017
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https://www.sciencedaily.com/releases/2017/04/170420132345.htm
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New research unlocks forests' potential in climate change mitigation
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New insights into the impact forests have on surface temperature will provide a valuable tool in efforts to mitigate climate change, according to a new research paper co-authored by Clemson University scientist Thomas O'Halloran.
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For the first time, scientists have created a global map measuring the cooling effect forests generate by regulating the exchange of water and energy between Earth's surface and the atmosphere. In many locations, this cooling effect works in concert with forests' absorption of carbon dioxide. By coupling information from satellites with local data from sensors mounted to research towers extending high above tree canopies, O'Halloran and his collaborators throughout the world have given a much more complete, diagnostic view of the roles forests play in regulating climate.Their findings have important implications for how and where different types of land cover can be used to mitigate climate change with forest protection programs and data-driven land-use policies. Results of their study were recently published in the journal "It's our hope that such global maps can be used to optimize biophysics in addition to carbon when planning land-use climate change mitigation projects," said O'Halloran, assistant professor of Forestry and Environmental Conservation at Clemson's Baruch Institute of Coastal Ecology and Forest Science in Georgetown.Previously, scientists measured vegetation's impact on local land temperatures using satellite imagery, which is limited to only clear-sky days and few measurements per day, or they used local stations, which are limited in their reach. Integrating data from towers extending more than 100 feet in the air with satellite measurements allows for a more advanced view of the variables impacting surface temperature. The research team found that forests' cooling effect was greater than thought and most pronounced in mid- and low-latitude regions.This new statistical model of analyzing forests' impact on local temperature will allow communities around the world to pinpoint ideal locations for forest protection or reforestation efforts."We wanted every country in the world to have some estimation of the cooling effects of forests and vegetation," O'Halloran said. "It's about optimizing the benefit of land management for climate change mitigation."A tower similar to those used for this study is under construction at Baruch in collaboration with the University of South Carolina to help provide greater analysis of local climate, he said."The towers will really help us understand how ecosystems respond to change," O'Halloran said. "In South Carolina, we've had a lot of extreme weather events, droughts, flood and hurricanes. This will help us understand the resilience of local ecosystems to those types of events."O'Halloran co-authored the article in Unlike local climate changes owed to global emissions of CO2 and other greenhouse gases, local climate changes linked to land-related activities are unique in that they are only influenced by the local land-use policies that are in place, Bright said."The results of our study now make it easier for individual nations or regions to begin measuring and enforcing climate policies resulting in tangible mitigation or adaptation benefits at the local scale," says Bright. "This is especially critical moving forward in a world facing increasing competition for land resources."
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Weather
| 2,017 |
April 11, 2017
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https://www.sciencedaily.com/releases/2017/04/170411085953.htm
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Stalagmites store paleoclimate data
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The North Atlantic Oscillation (NAO) is the dominant atmospheric pressure mode over the North Atlantic that plays a significant role in determining the winter climate in Europe. Depending on the prevailing state of the NAO, Europe experiences mild or very cold winters and even strong storms. Geoscientists based at Johannes Gutenberg University Mainz (JGU) in Germany are currently reconstructing the fluctuations of the NAO over the last 10,000 years with the aim of being able to predict future developments. For this purpose, they use stalagmites obtained from subterranean caves as natural climate archives and are examining new indicators of climate change to retrieve climate information that is as accurate as possible. Initial results indicate that it is likely that the NAO will respond to the melting of the Arctic ice cap in the future, with consequences for our climate, environment, and society as a whole.
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Dr. Jasper Wassenburg works with stalagmites from caves in the Middle Atlas, a mountain range in the northwest of Morocco. Stalagmites are calcium carbonate deposits that grow from the floor of a cave upwards due to precipitation of calcium carbonate minerals deposited from the dripwater. Calcite is the most common form of calcium carbonate although in some cases it can also be aragonite. "Aragonite, if well preserved, can be dated with remarkable precision. So we prefer aragonite stalagmites over calcitic ones," explained Wassenburg, who is a member of the research team headed by Professor Denis Scholz at the Institute of Geosciences at Mainz University.The incorporation of chemical elements in speleothems, which is the term scientists use for the secondary mineral deposits in caves, is often depending on changes in the environment. These elements are known as climate proxies because they provide indirect evidence of climatic history. Wassenburg's study of seven speleothem samples obtained from Morocco, India, France, Spain, and a cave known as the Hüttenbläserschachthöhle in Germany's Sauerland region is the first attempt to identify in detail the concentrations at which trace elements tend to be incorporated in aragonite. "We have been able to demonstrate that the concentration of uranium in aragonite stalagmites is a very precise indicator of prehistoric rainfall patterns," he added. This means that stalagmites can tell us qualitatively how much it rained 200,000 years ago.Uranium and strontium concentrations and the relative ratios of oxygen isotopes were also analyzed in order to obtain information on past rainfall for a recent study of past NAO variability. The NAO index reflects the difference in atmospheric pressure between the Icelandic Low to the north and the Azores High to the south. One particular phenomenon of interest is that if the NAO brings dry weather to Europe, it rains in Morocco—and vice versa. The weather of the northwestern region of Morocco seems to react particularly sensitive to changes in the NAO. In this case, the samples used by Dr. Jasper Wassenburg came from a fairly small cave in which the host rock is dolomite. The Grotte de Piste is located in the Atlas Mountains at an elevation of some 1,250 meters above sea level. It is 70 to 80 meters in extent and 15 to 20 meters from floor to ceiling.The results of analysis of the speleothems from the north-west of Morocco were compared with a rainfall reconstruction obtained from other cave deposits from the Bunkerhöhle or Bunker cave in western Germany. This enabled the climate researchers to trace back the fluctuations of the NAO over the past 11,000 years to the end of the last Ice Age. The best reconstruction previously available went back only 5,200 years. "We were surprised to discover that the situation during the early Holocene 11,000 years ago was quite different to that of today. The weather regimes in Europe and Morocco seem to have behaved similarly so that wet weather in Europe also meant more rain in Morocco," explained Wassenburg. This positive correlation disappeared at some point during the transition from the early Holocene to the mid-Holocene.The researchers postulate that this was attributable to a major reduction in the melt water contribution from the Laurentide Ice Sheet that still covered large areas of North America at the end of the Ice Age. "The pattern of the North Atlantic Oscillation is not as stable as we thought," stated Professor Dennis Scholz and added that the NAO will probably also be influenced by today's melting of the Greenland Ice Sheet, with potential effects on the atmosphere, the oceans, and other biological phenomena, including farming and fishing. The team plans to conduct further research in order to reconstruct the changes of the NAO over the last 10,000 years.
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Weather
| 2,017 |
April 10, 2017
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https://www.sciencedaily.com/releases/2017/04/170410155108.htm
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El Nino shifts geographic distribution of cholera cases in africa
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Cholera cases in East Africa increase by roughly 50,000 during El Niño, the cyclical weather occurrence that profoundly changes global weather patterns, new Johns Hopkins Bloomberg School of Public Health research suggests.
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The findings, researchers say, could help health ministries anticipate future cholera surges during El Niño years and save lives.The researchers, reporting April 10 in the "We usually know when El Niño is coming six to 12 months before it occurs," says study leader Justin Lessler, an associate professor of epidemiology at the Bloomberg School. "Knowing there is elevated cholera risk in a particular region can help reduce the number of deaths that result. If you have cholera treatment centers available, fast, supportive care can reduce the fatality rate from cholera from as high as 30 percent to next to nothing."The total number of cases of cholera across Africa as a whole were about the same in El Niño years as compared to non-El Niño years, the researchers found, but the geographic distribution of illnesses was fundamentally different. El Niño conditions in the equatorial Pacific region strongly impact weather conditions globally, including increasing rainfall in East Africa and decreasing rainfall in drier areas of northern and southern Africa.During the years classified as El Niño between 2000 and 2014, cholera incidence increased threefold in regions such as East Africa that had the strongest association between El Niño and cholera, with 177 million people living in areas that experienced an increase in cholera cases during a time of additional rainfall. At the same time, there were 30,000 fewer cases in southern Africa during El Niño where there was less rainfall than normal. Parts of central West Africa, however, saw significantly fewer cases of cholera, but with little change in rainfall patterns.While El Niño brings wetter and warmer weather to East Africa, rainfall is not the only variable that appears to impact cholera rates, Lessler says. Cholera is almost always linked to vulnerable water systems. In some areas, massive rainfall can overrun sewer systems and contaminate drinking water. In other locations, however, dry conditions can mean that clean water sources aren't available and people must consume water from sources known to be contaminated."Countries in East Africa, including Tanzania and Kenya, have experienced several large cholera outbreaks in recent decades," says study author Sean Moore, PhD, a post-doctoral fellow in the Bloomberg School's Department of Epidemiology. "Linking these outbreaks to El Niño events and increased rainfall improves our understanding of the environmental conditions that promote cholera transmission in the region and will help predict future outbreaks."For the study, Lessler, Moore and their colleagues collected data on cholera cases in Africa from 360 separate data sets, analyzing 17,000 annual observations from 3,710 different locations between 2000 and 2014.The researchers note that there were weak El Niño years from 2004 to 2007, while 2002-2003 and 2009-2010 were classified as moderate-to-strong El Niño years. They say that 2015-2016 was also an El Niño year with the largest cholera outbreak since the 1997-1998 El Niño occurring in Tanzania.Using this knowledge of a link between cholera and El Niño could allow countries to prepare for outbreaks long before they start, Lessler says. Currently, there is an approved vaccine for cholera, but its effects are not lifelong and there are not enough doses for everyone in areas that could be impacted by El Niño. Once there is more vaccine, he says, it can be another tool for health officials to use as they try to prevent deadly cholera in their nations.As climate change continues, disease patterns will continue to change as well, Lessler says. Often, the story is that climate change will put more people at risk for more types of diseases."But what the link between cholera and El Niño tells us is that changes may be subtler than that," he says. "There will be winners and losers. It's not a one-way street.""El Niño and the Shifting Geography of Cholera in Africa" was written by Sean Moore, Andrew Azman, Benjamin Zaitchik, Eric Mintz, Joan Brunkard, Dominique Legros, Alexandra Hill, Heather McKay, Francisco Luquero, David Olson and Justin Lessler.
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Weather
| 2,017 |
April 10, 2017
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https://www.sciencedaily.com/releases/2017/04/170410123943.htm
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Mild, wet summer in the midwest predicted by weather expert
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Following a dry, mild winter in the Midwest, a University of Missouri meteorology expert is predicting a relatively wet and mild summer for Missouri and much of the Midwest. Tony Lupo, a professor of atmospheric science at Mizzou, says normal temperatures and average rainfall this summer should help boost agriculture in the region after a dry winter.
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"Historically, after dry winters such as the one we just experienced, we typically see a pattern change and experience average to wetter-than-average summers," Lupo said. "We already are seeing the beginning of this shift with the very wet spring we have experienced so far. With milder temperatures and a healthy amount of rain, farmers around Missouri and much of the Midwest can hope to have great growing conditions for much of the summer."Lupo's forecast calls for slightly higher than normal corn and soybean yields throughout the state of Missouri, with the exception of southeast Missouri, which may see slightly below average yields. Lupo says the mild, average forecast for the summer can be attributed, at least in part, to the projected El Niño conditions in the Pacific Ocean."Early during the formation of El Niño patterns, the Midwest typically sees mild and wet summers, which is what we expect to experience this year," Lupo said. "While those conditions will probably change as El Niño advances, people in the Midwest should be able to enjoy the mild weather for this summer at least."Lupo published a study on his 2017 summer forecast, "ENSO and PDO-related climate variability impacts on Midwestern United States crop yields," in the
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Weather
| 2,017 |
April 10, 2017
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https://www.sciencedaily.com/releases/2017/04/170410085510.htm
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Large, high-intensity forest fires will increase
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When it comes to large, high-intensity forest fires, we can expect to see a lot more in the coming years, according to South Dakota State University professor Mark Cochrane, a senior scientist at the Geospatial Sciences Center of Excellence.
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Using satellite data from 2002 to 2013, Cochrane and researchers from the University of Tasmania and the University of Idaho examined nearly 23,000 fires worldwide, identifying 478 large, high-intensity fires which they defined as extreme wildfire events. Their work is described in the Feb. 2017 issue of "Almost all happened under bad conditions -- high temperatures, dry conditions and strong winds, which tell us that weather and climate are very important," Cochrane said. Using monthly world weather data from 2000 to 2014, the researchers modeled the likely changes in fire behavior from 2041 to 2070, predicting a 20 to 50 percent increase in the number of days when conditions are conducive to fires."Those conditions are based on business-as-usual carbon emissions," Cochrane continued. "This will continue to worsen after 2070 unless we get very serious about cutting global carbon emissions."By 2041, there will likely be 35 percent more of these large, catastrophic fires per decade, according to Cochrane. "That translates to four extreme fire events for every three that occur now."However, that risk is not spread evenly, Cochrane explained. Forests in the western United States, southeastern Australia, Europe and the eastern Mediterranean region that extends from Greece to Lebanon and Syria are among those areas at highest risk.Though the concept of huge, devastating wildfires, sometimes called megafires, has been tossed around, Cochrane said, "There is no operational definition." Therefore, the research team, led by University of Tasmania professor David Bowman, examined fire intensity and area.First, the researchers identified hotspots using moderate resolution imaging spectroradiometer, or MODIS, from two earth-imaging satellites to measure the amount of heat energy released, known as fire radiative power. To do this, they looked at the total energy being released in each 25,000-acre block across the planet, Cochrane explained. "It's a combination of the area that is burning and the intensity at which it is burning."Through that analysis, the researchers identified 478 extreme fire events. "We limited ourselves to the top .003 percent," he said. "Anyone would agree that these are pretty intense, large events."They further narrowed the extreme fire events to ones that had the greatest impact on humans. "Fires in the boreal forest might be very large, but they do not impact many people," he pointed out. "We looked for those in which people had to clear out of the way."The researchers identified 144 fires that were catastrophic, meaning people died and homes were destroyed. "Most of these fires were in the western United States and southeastern Australia, which have fairly high population densities," Cochrane said.Wind-driven fires accounted for nearly 35 percent of these catastrophic events, while severe drought was a factor in nearly 22 percent. Other extreme fire weather conditions, largely due to high temperatures and low humidity, accounted for slightly more than 20 percent of these costly fires."Not only is climate making things worse, but people are building homes in these flammable landscapes," he said.
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Weather
| 2,017 |
April 6, 2017
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https://www.sciencedaily.com/releases/2017/04/170406171917.htm
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Meteorologist applies biological evolution to forecasting
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Weather forecasters rely on statistical models to find and sort patterns in large amounts of data. Still, the weather remains stubbornly difficult to predict because it is constantly changing.
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"When we measure the current state of the atmosphere, we are not measuring every point in three-dimensional space," says Paul Roebber, a meteorologist at the University of Wisconsin-Milwaukee. "We're interpolating what happens in the in-between."To boost the accuracy, forecasters don't rely on just one model. They use "ensemble" modeling -- which takes an average of many different weather models. But ensemble modeling isn't as accurate as it could be unless new data are collected and added. That can be expensive.So Roebber applied a mathematical equivalent of Charles Darwin's theory of evolution to the problem. He devised a method in which one computer program sorts 10,000 other ones, improving itself over time using strategies, such as heredity, mutation and natural selection."This was just a pie-in-the-sky idea at first," says Roebber, a UWM distinguished professor of atmospheric sciences, who has been honing his method for five years. "But in the last year, I've gotten $500,000 of funding behind it."His forecasting method has outperformed the models used by the National Weather Service. When compared to standard weather prediction modeling, Roebber's evolutionary methodology performs particularly well on longer-range forecasts and extreme events, when an accurate forecast is needed the most.Between 30 and 40 percent of the U.S. economy is somehow dependent on weather prediction. So even a small improvement in the accuracy of a forecast could save millions of dollars annually for industries like shipping, utilities, construction and agribusiness.The trouble with ensemble models is the data they contain tend to be too similar. That makes it difficult to distinguish relevant variables from irrelevant ones -- what statistician Nate Silver calls the "signal" and the "noise."How do you gain diversity in the data without collecting more of it? Roebber was inspired by how nature does it.Nature favors diversity because it foils the possibility of one threat destroying an entire population at once. Darwin observed this in a population of Galapagos Islands finches in 1835. The birds divided into smaller groups, each residing in different locations around the islands. Over time, they adapted to their specific habitat, making each group distinct from the others.Applying this to weather prediction models, Roebber began by subdividing the existing variables into conditional scenarios: The value of a variable would be set one way under one condition, but be set differently under another condition.The computer program he created picks out the variables that best accomplishes the goal and then recombines them. In terms of weather prediction, that means, the "offspring" models improve in accuracy because they block more of the unhelpful attributes."One difference between this and biology is, I wanted to force the next generation [of models] to be better in some absolute sense, not just survive," Roebber said.He is already using the technique to forecast minimum and maximum temperatures for seven days out.Roebber often thinks across disciplines in his research. Ten years ago, he was at the forefront of building forecast simulations that were organized like neurons in the brain. From the work, he created an "artificial neural network" tool, now used by the National Weather Service, that significantly improves snowfall prediction.
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Weather
| 2,017 |
April 6, 2017
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https://www.sciencedaily.com/releases/2017/04/170406102621.htm
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Scientists link California droughts, floods to distinctive atmospheric waves
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The crippling wintertime droughts that struck California from 2013 to 2015, as well as this year's unusually wet California winter, appear to be associated with the same phenomenon: a distinctive wave pattern that emerges in the upper atmosphere and circles the globe.
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Scientists at the National Center for Atmospheric Research (NCAR) found in a recent study that the persistent high-pressure ridge off the west coast of North America that blocked storms from coming onshore during the winters of 2013-14 and 2014-15 was associated with the wave pattern, which they call wavenumber-5. Follow-up work showed that wavenumber-5 emerged again this winter but with its high- and low-pressure features in a different position, allowing drenching storms from the Pacific to make landfall."This wave pattern is a global dynamic system that sometimes makes droughts or floods in California more likely to occur," said NCAR scientist Haiyan Teng, lead author of the California paper. "As we learn more, this may eventually open a new window to long-term predictability."The finding is part of an emerging body of research into the wave pattern that holds the promise of better understanding seasonal weather patterns in California and elsewhere. Another new paper, led by NCAR scientist Grant Branstator, examines the powerful wave pattern in more depth, analyzing the physical processes that help lead to its formation as well as its seasonal variations and how it varies in strength and location.The California study was published in the The new papers follow a 2013 study by Teng and Branstator showing that a pattern related to wavenumber-5 tended to emerge about 15-20 days before major summertime heat waves in the United States.Wavenumber-5 consists of five pairs of alternating high- and low-pressure features that encircle the globe about six miles (10 kilometers) above the ground. It is a type of atmospheric phenomenon known as a Rossby wave, a very large-scale planetary wave that can have strong impacts on local weather systems by moving heat and moisture between the tropics and higher latitudes as well as between oceanic and inland areas and by influencing where storms occur.The slow-moving Rossby waves at times become almost stationary. When they do, the result can be persistent weather patterns that often lead to droughts, floods, and heat waves. Wavenumber-5 often has this stationary quality when it emerges during the northern winter, and, as a result, is associated with a greater likelihood of persistent extreme events.To determine the degree to which the wave pattern influenced the California drought, Teng and Branstator used three specialized computer models, as well as California rainfall records and 20th century data about global atmospheric circulation patterns. The different windows into the atmosphere and precipitation patterns revealed that the formation of a ridge by the California coast is associated with the emergence of the distinctive wavenumber-5 pattern, which guides rain-producing low-pressure systems so that they travel well north of California.Over the past winter, as California was lashed by a series of intense storms, wavenumber-5 was also present, the scientists said. But the pattern had shifted over North America, replacing the high-pressure ridge off the coast with a low-pressure trough. The result was that the storms that were forced north during the drought winters were, instead, allowed to make landfall.Forecasters who predict seasonal weather patterns have largely looked to shifting sea surface temperatures in the tropical Pacific, especially changes associated with El Niño and La Niña. But during the dry winters of 2013-14 and 2014-15, those conditions varied markedly: one featured the beginning of an El Niño while the sea surface temperatures during the other were not characteristic of either El Niño or La Niña.The new research indicates that the wave pattern may provide an additional source of predictability that sometimes may be more important than the impacts of sea surface temperature changes. First, however, scientists need to better understand why and when the wave pattern emerges.In the paper published in Journal of the Atmospheric Sciences, Branstator and Teng explored the physics of the wave pattern. Using a simplified computer model of the climate system to identify the essential physical processes, the pair found that wavenumber-5 forms when strong jet streams act as wave guides, tightening the otherwise meandering Rossby wave into the signature configuration of five highs and five lows."The jets act to focus the energy," Branstator said. "When the jets are present, the energy is trapped and cannot escape." But even when the jets are present, the wavenumber-5 pattern does not always form, indicating that other forces requiring study are also at play.The scientists also searched specifically for what might have caused the wave pattern linked to the severe California drought to form. In the paper published in the Journal of Climate, the pair found that extremely heavy rainfall from December to February in certain regions of the tropical Pacific could double the probability that the extreme ridge associated with wavenumber-5 will form. The reason may have to do with the tropical rain heating parts of the upper atmosphere in such a way that favors the formation of the wavenumber-5 pattern.But the scientists cautioned that many questions remain."We need to search globally for factors that cause this wavenumber-5 behavior," Teng said, "Our studies are just the beginning of that search."
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Weather
| 2,017 |
April 6, 2017
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https://www.sciencedaily.com/releases/2017/04/170406102557.htm
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Unraveling the mystery of snowflakes, from the Alps to Antarctica
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Imagine taking pictures of thousands of snowflakes from three different angles with a specialized instrument installed at an altitude of 2,500 meters. Then imagine using 3,500 of these pictures to manually train an algorithm to recognize six different classes of snowflakes. And, finally, imagine using this algorithm to classify the snowflakes in the millions of remaining pictures into those six classes at breakneck speed. That's exactly what researchers at EPFL's Environmental Remote Sensing Laboratory (LTE) did, in a project spearheaded by Alexis Berne. Their pioneering approach was featured in the latest issue of
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"The scientific community has been trying to improve precipitation measurement and forecast for over 50 years. We now have a pretty good understanding of the mechanisms involved in rain," says Berne. "But snow is a lot more complicated. Many factors -- like the shape, geometry and electromagnetic properties of individual snowflakes -- affect how snow crystals reflect signals back to weather radars, making our task much harder. And we still don't have a good grasp of the equivalent liquid water content of snowflakes. Our goal with this study was to better understand exactly what's falling when it snows, so that we can eventually improve snowfall forecast at high altitudes." Berne also sees other applications for the team's findings, like a more accurate estimation of water equivalent stored in the snowpack for irrigation and hydropower.To reach their goal, the researchers acquired a Multi-Angle Snowflake Camera (MASC)- a sophisticated instrument composed by three synchronized cameras that simultaneously take high resolution (up to 35-micron) pictures of snowflakes as they pass through a metallic ring.In collaboration with the Federal Office of Meteorology and Climatology MeteoSwiss and the Institute for Snow and Avalanche Research, they installed the MASC at a site near Davos, at an altitude of 2,500 meters, where it took pictures for an entire winter and at a site in coastal Antarctica, where it took pictures for an entire austral summer. They then ran their algorithm to classify the snowflake images into six main classes based on existing classification: planar crystals, columnar crystals, graupels, aggregates, combination of column and planar crystals, and small particles.The researchers used the pictures taken by the MASC to also determine the degree of riming of each snowflake based on its surface roughness (image 3). "Snowflakes change shape as they fall down the atmosphere -- especially through clouds," says Berne. "Some of them gather frost and become more or less rimed snow crystals [#3-5 in the image], while others remain pristin and have a very low riming index." Riming is important because it is the process that turns cloud water droplets into precipitation in the form of ice -- in other words, snow.The next step was to compare the results obtained from the pictures taken near Davos in the Swiss Alps with those taken in Adélie Land on the coast of Antarctica. That revealed significant differences in how often every snowflake family appeared. Most of the snowflakes in the Alps are aggregates (49%), followed by small particles and graupels. However, in Antarctica, the majority were small particles (54%), followed by aggregates and graupels.According to Berne, these differences can be explained. "The fierce Antarctic winds continually erode the snowpack and result in the formation of tiny snow particles. What's more, Antarctic snowflakes have much less riming than Alpine snowflakes because the Antarctic air is a lot drier." Another of the researchers' findings that will perhaps disappoint purists is that the 'stellar dendrite' type of snowflake -- the one we typically associate with the 'ideal' snowflake -- turned out to be rare at both sites, making up only 10% of snowflakes in the Alps and 5% of snowflakes in Antarctica.To tackle the complexity of the multiple processes involved, scientists usually rely on several different instruments when making meteorological measurements and weather forecasts. The results obtained by Berne's team will therefore provide even more insights when combined with other instruments, such as weather radars, which collect data on clouds and precipitation across all layers of the atmosphere.As part of the international Solid Precipitation Intercomparison Experiment (SPICE), MeteoSwiss set up a rain gauge next to the MASC at the Davos site. The data have not been yet fully analyzed, but by comparing the type of snowflakes photographed by the MASC with the amount of water collected over a given period, the team will be able to test various hypotheses on snowflake liquid water content, which remains an enigma for atmospheric scientists.To bolster their findings, Berne's team needs to gather more data. They sent their MASC back to Antarctica for another data-collecting round this year; it will then head to the mountains of South Korea in 2018 for the Winter Olympics which will take place in Pyeongchang. "The more data we have, the more reliable our calculations will be," says Berne.This research project combines fundamental and applied research. It involves three scientists: Alexis Berne and Christophe Praz from EPFL's Environmental Remote Sensing Laboratory and Yves-Alain Roulet from MeteoSwiss (the Federal Office of Meteorology and Climatology). MeteoSwiss has been working with EPFL for several years to improve its precipitation estimates and its numerical weather prediction model.
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Weather
| 2,017 |
April 4, 2017
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https://www.sciencedaily.com/releases/2017/04/170404160052.htm
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Melting snow contains a toxic cocktail of pollutants
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With spring finally here and warmer temperatures just around the corner, snow will slowly melt away, releasing us from the clutches of winter. However, that's not the only thing that the melting snow will release. Researchers from McGill University and École de technologie supérieure in Montreal have found that urban snow accumulates a toxic cocktail from car emissions -- pollutants that are in turn unleashed into the environment as the weather warms up.
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"We found that snow absorbs certain polycyclic aromatic hydrocarbons which are organic pollutants known to be toxic and carcinogenic," says Yevgen Nazarenko, a postdoctoral researcher working with Parisa A. Ariya, professor at McGill's Department of Atmospheric and Oceanic Sciences and Department of Chemistry, and collaborating with Prof. Patrice Seers' team at École de technologie supérieure."Understanding how these pollutants interact with the environment, including snow, is crucial if we are to reduce the hundreds of thousands of premature deaths caused by mild air pollution in North America. Worldwide, air pollution claims as many as 8 million lives," says Prof. Ariya, senior author of the group's new study, published in In some cases, it doesn't take high-tech equipment to sniff out shifting pollution levels."When one goes outdoors in winter, and there is fresh snow, one can sense the air has a different smell -- it usually smells 'crisper'. Once the snow has been on the ground for some time, the effect goes away. When the weather warms up, the air acquires yet another smell. This is what led us to wonder about how exactly snow interacts with air pollutants," says Nazarenko.The scientists analyzed how snow takes up pollutants from car emissions by exposing it to engine exhaust in a frozen glass sphere built in the lab. They found that exhaust is affected differently by the cold and snow depending on the type of fuel injection in the engine.The new study also found that snow takes up airborne particulate matter and alters the concentrations of different nanoparticles, the smallest particles found in air pollution. These tiny particles have been linked to numerous health problems. Unexpectedly, colder temperatures and interaction with snow increased the relative presence of smaller nanoparticles in the polluted air above the snow.Once in the snowpack, air pollutants may undergo chemical transformations that create additional pollutants with different toxicity and carcinogenicity. Some compounds, including more toxic and carcinogenic chemicals, may volatilize back into the air, while others accumulate in the snow and are released with meltwater."These releases could lead to a higher short-term concentration of certain pollutants in the air, soil and surface water bodies where the meltwater runs to," worries Nazarenko.Further studies and environmental monitoring could help identify the most harmful pollutants, which ones should be targeted for reduction in gasoline formulations and in optimization of engines and exhaust treatment technologies, the researchers conclude.
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Weather
| 2,017 |
April 3, 2017
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https://www.sciencedaily.com/releases/2017/04/170403123252.htm
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Close connection between deep currents and climate
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Mild winters in northern Europe, rainfall in western Africa, hurricanes in North America -the energy transported around the world by the global ocean circulation affects the climate as well as regional weather phenomena. One of the key regions for the ocean circulation is the Labrador Sea between North America and Greenland. There warm, saline waters coming from the south near the sea surface cool down and sink to the depth. There the water masses flow back to the south along the continental margin. Thereby the area is one of the regions of crucial importance for the global ocean circulation.
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At the southern exit of the Labrador Sea, the GEOMAR Helmholtz Center for Ocean Research Kiel has been operating oceanographic observatories since 1997 that cover all levels of this current system. A team of four oceanographers now published the most complete analysis of these data in the GEOMAR's oceanographic observatories are located at 53° North on the western boundary of the Labrador Sea. They consist of a series of current meters and sensors for temperature and salinity attached to chains and steel cables. Anchor weights at the lower end hold these so-called moorings in place while buoyant floatation pull the other end towards the surface. "This allows us to measure the currents from just below the surface to just above the ground," explains Rainer Zantopp. In addition, the study is based on data collected by the researchers during a total of 13 scientific cruises in the area between 1996 and 2014, mainly with the German research vessels METEOR and MARIA S. MERIAN, as well as with the French research vessel THALASSA.The analysis showed that the southward deep currents along the western boundary of the Atlantic have fluctuations on different time scales. The authors were especially surprised by the deepest current near the ocean floor. "Although it is more steady than those at the upper levels, it varies with an almost ten-year rperiod," Rainer Zantopp says.Further analysis showed that the fluctuations of the deepest flow are synchronous with those of wind systems over the North Atlantic which are influenced by the pressure difference between the Azores high and the Iceland low. The indicator is called the North Atlantic Oscillation (NAO). "The intensity of the deepest southward current from the Labrador Sea shows similar fluctuations as the NAO," explains Rainer Zantopp. "We were somewhat surprised to find the signal so clearly in our measurement data."These results from oceanographic long-term observations are of great importance for general climate research. "The better we understand the interactions between the ocean and the atmosphere, the more reliably we can distinguish natural variabilities and man-made changes and thus make better predictions about future developments," emphasizes Rainer Zantopp .
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Weather
| 2,017 |
March 29, 2017
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https://www.sciencedaily.com/releases/2017/03/170329122619.htm
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'Weather whiplash' triggered by changing climate will degrade Midwest's drinking water
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One consequence of global climate change is the likelihood of more extreme seesawing between drought and flood, a phenomenon dubbed "weather whiplash."
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Now, researchers at the University of Kansas have published findings in the journal "As rainfall patterns change with climate change, it's predicted there will be more times of drought, and more times of excessive rainfall -- really big storms," said Terry Loecke, assistant professor of environmental studies at the University of Kansas and lead author of the new investigation.Loecke and co-author Amy Burgin, associate professor of environmental studies, said the extreme flux between drought and rainfall changes the storage of nutrients in the agricultural landscape -- nitrogen used in fertilizing farms most importantly."Farmers put on their normal amount of fertilizer, but when we have a drought, plants don't grow as big and don't take up as much nitrogen," Loecke said. "Instead of going into the plants, which would be harvested, it stays in the soil -- and no water is flushing it away."But when floods occur, nitrogen is washed into surface waters such as tributaries that feed into rivers."The soil is like a sponge, and when it's dry the nitrogen stays put," Burgin said. "But as soon as you wet it, like when you wring a sponge, the nitrogen can flood into the rivers."Because many of these rivers supply drinking water for communities throughout middle America, remediating high loads of nitrogen will stress taxpayers as water departments are forced to build new facilities to eliminate nitrogen from municipal water supplies.The KU researchers, along with Diego Riveros-Iregui of the University of North Carolina at Chapel Hill, Adam Ward of Indiana University, Steven Thomas of the University of Nebraska-Lincoln, Caroline Davis of the University of Iowa and Martin St. Clair of Coe College, analyzed data from the U.S. Geological Survey and the National Oceanic and Atmospheric Administration as well as other sources.The team took a close look at a 2012-2013 drought and flood cycle that affected much of the Midwestern U.S., leading to a nitrogen spike in surface waters."We looked at observations of the 2012 drought that ended in a flood and asked how frequently that has occurred across upper Midwest across in the last 10-15 years," Loecke said. "We found that the connection between drought-to-flood conditions and high nitrate was pretty common."Indeed, skyrocketing nitrate levels in the Des Moines and Raccoon rivers forced the Des Moines Water Works to construct a $4.1 million nitrate removal plant that costs $7,000 per day to operate."The drinking water is a real problem, especially in Des Moines," Burgin said. "It has one of most expensive nitrate-removal facilities that we know about. In recent years, they've been running it from 25 to 150-plus days each year. That's really adding up, because the money isn't in the budget they have to spend to get clean drinking water to citizens."Recently, the water utility sued several farm-dense Iowa counties upriver from the city to recoup its denitrification costs.According to Loecke and Burgin, who both also serve as scientists with the Kansas Biological Survey, surface-water nitrate spikes like the ones plaguing Iowa will occur more widely throughout the agricultural Midwest as weather whiplash becomes more commonplace in the region."The average person will pay more to have clean drinking water, like in the city of Des Moines," Loecke said. "A city can't predict how many days they'll have to run a nitrate-removal facility. When they run it a lot, it's a huge hit to their budget, and they have to pass it on to their citizens, and it will spread out to rest of the Midwest. Midwesterners will have to pay more for drinking water going forward."Loecke and Burgin said they hoped their research could help inform farmers, policymakers, water departments and the general public."Municipal water services should be paying attention," Burgin said. "Iowa is the bull's-eye of this problem, and it's going to spread out from there -- this might not be at the forefront of a lot of Kansas minds right now. But given it's an agricultural state, it's a matter of time before we're in same boat. In Iowa, now it's hitting smaller municipalities. According to analysis by the Des Moines Register, 30 percent of them will have this problem -- and most don't have the tax bases to support huge nitrate-removal facilities."The National Science Foundation supported this work.
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Weather
| 2,017 |
March 29, 2017
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https://www.sciencedaily.com/releases/2017/03/170329102539.htm
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Adding grads, going green can brighten economic outlook
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Attracting college graduates and boosting natural amenities may give communities a double shot of economic growth potential, according to economists.
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In a study, the share of college graduates -- often referred to as human capital -- and the quality of life in a community were found to significantly contribute to economic growth, said Stephan Goetz, professor of agricultural and regional economics, Penn State and director of the Northeast Regional Center for Rural Development."We've always known that human capital is important for economic growth and we are also learning that counties that have good amenities and quality of life factors -- mountain views, lakes, shores, and clean environment, for example -- are doing quite well, but we haven't looked at having both of these together in a county at the same time and what the policy implications might be," said Goetz. "It turns out they are mutually reinforcing. If you have more human capital in an area with better amenities that gives growth an additional boost."According to the researchers, both quality of life -- including amenities such as clean air, hiking trails, beaches and a temperate climate -- and the number of college-educated citizens can positively affect wage growth.The growth effect from quality of life and human capital is more pronounced in rural -- nonmetro -- counties, the researchers said."The rural counties are often the places struggling to find ways to boost growth, so this may be important news for them," said Goetz.He added that quality of life and human capital can be interrelated and mutually supporting in communities."If you attract educated individuals they may want to influence environmental policy, or find ways to improve the local quality of life, thus reinforcing the effects of quality of life on economic growth," said Goetz. "Likewise, you may see that places with improving quality of life may attract educated people."Communities may want to take advantage of the combined effect of human capital and natural amenities to create programs that attract and retain college graduates and improve the environment, said study co-author Qin Fan, assistant professor of economics, California State University, Fresno."Our study suggests that the effect of human capital on economic growth is larger in high-quality-of-life counties -- natural amenities such as clean air and temperate climate, could potentially attract human capital and perhaps increase labor productivity, thus boosting the effect of human capital on growth," said Fan. "Our results provide empirical support for community development strategies through preserving or promoting natural amenities that improve quality of life and retain human capital."The researchers, who reported their findings in a recent issue of Extreme weather conditions can affect wage growth, which is the increase in average county wages. As the mean temperature rises, for instance, wage growth is significantly suppressed, said Goetz, who also worked with and Jiaochen Liang, assistant professor of agricultural business, California State University, Fresno."Also, heavy precipitation can suppress growth," he added. "We are experiencing more abnormal weather events -- think of the recent flooding in California -- and that can suppress wage growth."While communities often use tax breaks to attract business, the researchers suggest that instead reinvesting some of that money into infrastructure and natural enhancements may attract entrepreneurs and business owners."There's often this idea that businesses will only locate in places with the lowest taxes, but when that means that the roads deteriorate and bridges fall apart that doesn't attract businesses," said Goetz. "One of the implications of this study is that if quality of life is tied to public services and public spending, then cutting taxes needlessly is counter-productive."
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Weather
| 2,017 |
March 28, 2017
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https://www.sciencedaily.com/releases/2017/03/170328135511.htm
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Can intergenerational cooperation defeat climate change?
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Older adults are powerful allies in addressing climate change, according to "Gray and Green Together: Climate Change in an Aging World," the latest edition of
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Research shows that older adults are at risk for the effects of extreme weather events and climate change; but they are also a potential resource for climate action. The new PP&AR highlights ways that this demographic can meet the climate change challenge on behalf of themselves, their descendants, and the population at large.Bucknell University professor and GSA Fellow Michael A. Smyer, PhD, played a central role in organizing the new publication. He currently is a Civic Innovation Fellow at Stanford University's Hasso Plattner Institute of Design (the d.school), where he is combining human-centered design, gerontology, and climate communication strategies to engage older adults on climate change."This is a timely issue of PP&AR," Smyer said. "Older adults represent a growing and largely untapped resource on climate action. The articles represent a range of views about that resource and how to engage them."The first steps older adults can take are individually oriented, the PP&AR demonstrates. For some, it is driving less; for others, it is having an energy audit; for someone else, it is saving energy by washing clothes in cold water.Eventually, several articles contend, older adults need to exert leadership in their families and communities -- making sure that local, state, and federal office holders understand that they are concerned about climate change and taking actions that will contribute a better future for future generations."Importantly, however, the authors do not see older adults solely as victims of climate change but also as leaders of climate action," Smyer said. "The time is now for that action -- those 60 and above have time, talent, and a desire for a sense of purpose as they reap the benefits of their longevity bonus."For more information, please see:
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Weather
| 2,017 |
March 27, 2017
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https://www.sciencedaily.com/releases/2017/03/170327114408.htm
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Planetary waves, first found on Earth, are discovered on sun
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The same kind of large-scale planetary waves that meander through the atmosphere high above Earth's surface may also exist on the Sun, according to a new study led by a scientist at the National Center for Atmospheric Research (NCAR).
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Just as the large-scale waves that form on Earth, known as Rossby waves, influence local weather patterns, the waves discovered on the Sun may be intimately tied to solar activity, including the formation of sunspots, active regions, and the eruption of solar flares."The discovery of magnetized Rossby waves on the Sun offers the tantalizing possibility that we can predict space weather much further in advance," said NCAR scientist Scott McIntosh, lead author of the paper.The study will be published March 27 in the journal The research was funded by the National Science Foundation (NSF), which is NCAR's sponsor, and by NASA.On Earth, Rossby waves are associated with the path of the jet stream and the formation of low- and high-pressure systems, which in turn influence local weather events.The waves form in rotating fluids -- in the atmosphere and in the oceans. Because the Sun is also rotating, and because it's made largely of plasma that acts, in some ways, like a vast magnetized ocean, the existence of Rossby-like waves should not come as a surprise, said McIntosh, who directs NCAR's High Altitude Observatory.And yet scientists have lacked the tools to distinguish this wave pattern until recently. Unlike Earth, which is scrutinized at numerous angles by satellites in space, scientists historically have been able to study the Sun from only one viewpoint: as seen from the direction of Earth.But for a brief period, from 2011 to 2014, scientists had the unprecedented opportunity to see the Sun's entire atmosphere at once. During that time, observations from NASA's Solar Dynamics Observatory (SDO), which sits between the Sun and the Earth, were supplemented by measurements from NASA's Solar TErrestrial RElations Observatory (STEREO) mission, which included two spacecraft orbiting the Sun. Collectively, the three observatories provided a 360-degree view of the Sun until contact was lost with one of the STEREO spacecraft in 2014. McIntosh and his co-authors mined the data collected during the window of full solar coverage to see if the large-scale wave patterns might emerge."By combining the data from all three satellites we can see the entire sun and that's important for studies like this because you want the measurements to all be at the same time," said Dean Pesnell, SDO project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "They're pushing the boundary of how we use solar data to understand the interior of the sun and where the magnetic field of the sun comes from."The team used images taken by instruments on SDO and STEREO to identify and track coronal bright points. These small bright features dot the entire face of the Sun and have been used to track motions deeper in the solar atmosphere.The scientists plotted the combined data on Hovmöller diagrams, a diagnostic tool developed by meteorologists to highlight the role of waves in Earth's atmosphere. What emerged from the analysis were bands of magnetized activity that propagate slowly across the Sun -- just like the Rossby waves found on Earth.The discovery could link a range of solar phenomena that are also related to the Sun's magnetic field, including the formation of sunspots, their lifetimes, and the origin of the Sun's 11-year solar cycle. "It's possible that it's all tied together, but we needed to have a global perspective to see that," McIntosh said. "We believe that people have been observing the impacts of these Rossby-like waves for decades, but haven't been able to put the whole picture together."With a new understanding of what the big picture might really look like, scientists could take a step closer to predicting the Sun's behavior."The discovery of Rossby-like waves on the Sun could be important for the prediction of solar storms, the main drivers of space weather effects on Earth," said Ilia Roussev, program director in NSF's Division of Atmospheric and Geospace Sciences. "Bad weather in space can hinder or damage satellite operations, and communication and navigation systems, as well as cause power-grid outages leading to tremendous socioeconomic losses. Estimates put the cost of space weather hazards at $10 billion per year."But to advance our predictive capabilities, scientists must first gain a better understanding of the waves and the patterns that persist on them, which would require once again having a 360-degree view of the Sun."To connect the local scale with the global scale, we need to expand our view," McIntosh said. "We need a constellation of spacecraft that circle the Sun and monitor the evolution of its global magnetic field."
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March 27, 2017
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https://www.sciencedaily.com/releases/2017/03/170327114329.htm
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Farming becoming riskier under climate change
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Scientists the world over are working to predict how climate change will affect our planet. It is an extremely complex puzzle with many moving parts, but a few patterns have been consistent, including the prediction that farming as we know it will become more difficult.
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Scientists infer the impact on agriculture based on predictions of rainfall, drought intensity, and weather volatility. Until now, however, the average farmer may not have been able to put predictions like these into practice. A new University of Illinois study puts climate change predictions in terms that farmers are used to: field working days."Everything else flows from field working days," says U of I and USDA Agricultural Research Service ecologist Adam Davis. "If you're not able to work, everything else gets backed up. Workable days will determine the cultivars, the cropping system, and the types of pest management practices you can use. We're simply asking, 'Can you get in to plant your crop?'"In a previous study, the group developed models that reliably translated past climate data into field working days for Illinois. In the new study, they coupled those models with climate change scenarios to forecast field working days into the future.The group ran the models for nine crop districts in Illinois for two time periods, mid-century (2046 to 2065) and late-century (2080 to 2099), using three climate scenarios ranging from mild to extreme.The models suggest that the typical planting window for corn will no longer be workable; April and May will be far too wet to work the fields in most parts of Illinois."Going forward, we're predicting warmer and wetter springs, and drier, hotter summers," Davis says. "The season fragments and we start to see an early-early season, so that March starts looking like a good target for planting in the future. In the past, March has been the bleeding edge; nobody in their right mind would have planted then. But we've already seen the trend for early planting. It's going to keep trending in that direction for summer annuals."Those drier, hotter summers are likely to change farming practices too, particularly in southern Illinois."Drought periods will intensify in mid- to late-summer under all the climate scenarios. If farmers decide to plant later to avoid the wet period in April and May, they're going to run into drought that will hit yield during the anthesis-silking interval, leading to a lot of kernel abortion. That second planting window is probably pretty risky," Davis says.Risk is the key word. If farmers bet on the early planting window and get hit with a frost or more March precipitation than expected, are they out of luck? Davis says they will have to choose to mud the seed in, plant a different hybrid, or even scrap corn and go for winter wheat later in the season. But given that many farmers choose hybrids and purchase seeds the previous fall, they're unlikely to have that kind of flexibility come spring. Any miscalculation will be incredibly costly."It will come down to whether crop insurers will move planting dates earlier in the spring. They're going to need enough years of empirical evidence that this early window exists before they are likely to make that change," Davis notes.The researcher suggests three strategies to cope with the changes. Farmers could plant early with long-season cultivars to maximize yield potential, betting on a pollination window to open up before the drought kicks in. Or farmers could choose shorter-season cultivars, planting early and then harvesting before the drought, possibly sacrificing yield.The last strategy will require a more radical shift."Create cropping systems that can deal with increased volatility by conserving soil moisture. Most of the effort in yield stability and resilience focuses on genetic improvement of crops. That's good, but I think we've fallen behind in the cropping system management side. If you've got an elite cultivar that's drought resistant in the same old cropping system that's not shifting with environmental changes, then we're not doing full justice to that cultivar," Davis says.Given the weather in Illinois this late winter/early spring, this work seems particularly timely."All this weird weather? It's part of a trend," Davis says. "Now is the time to prepare, because the future is here."
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| 2,017 |
March 27, 2017
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https://www.sciencedaily.com/releases/2017/03/170327083120.htm
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Extreme weather events linked to climate change impact on the jet stream
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Unprecedented summer warmth and flooding, forest fires, drought and torrential rain -- extreme weather events are occurring more and more often, but now an international team of climate scientists has found a connection between many extreme weather events and the impact climate change is having on the jet stream.
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"We came as close as one can to demonstrating a direct link between climate change and a large family of extreme recent weather events," said Michael Mann, distinguished professor of atmospheric science and director, Earth System Science Center, Penn State. "Short of actually identifying the events in the climate models."The unusual weather events that piqued the researchers' interest are things such as the 2003 European heat wave, the 2010 Pakistan flood and Russian heatwave, the 2011 Texas and Oklahoma heat wave and drought and the 2015 California wildfires.The researchers looked at a combination of roughly 50 climate models from around the world that are part of the Coupled Model Intercomparison Project Phase 5 (CMIP5), which is part of the World Climate Research Programme. These models are run using specific scenarios and producing simulated data that can be evaluated across the different models. However, while the models are useful for examining large-scale climate patterns and how they are likely to evolve over time, they cannot be relied on for an accurate depiction of extreme weather events. That is where actual observations prove critical.The researchers looked at the historical atmospheric observations to document the conditions under which extreme weather patterns form and persist. These conditions occur when the jet stream, a global atmospheric wave of air that encompasses the Earth, becomes stationary and the peaks and troughs remain locked in place."Most stationary jet stream disturbances, however, will dissipate over time," said Mann. "Under certain circumstances the wave disturbance is effectively constrained by an atmospheric wave guide, something similar to the way a coaxial cable guides a television signal. Disturbances then cannot easily dissipate, and very large amplitude swings in the jet stream north and south can remain in place as it rounds the globe."This constrained configuration of the jet stream is like a rollercoaster with high peaks and valleys, but only forms when there are six, seven or eight pairs of peaks and valleys surrounding the globe. The jet stream can then behave as if there is a waveguide -- uncrossable barriers in the north and south -- and a wave with large peaks and valleys can occur."If the same weather persists for weeks on end in one region, then sunny days can turn into a serious heat wave and drought, and lasting rains can lead to flooding," said Stefan Rahmstorf, Potsdam Institute for Climate Impact Research (PIK), Germany.The structure of the jet stream relates to its latitude and the temperature gradient from north to south.Temperatures typically have the steepest gradients in mid-latitudes and a strong circumpolar jet stream arises. However, when these temperature gradients decrease in just the right way, a weakened "double peak" jet stream arises with the strongest jet stream winds located to the north and south of the mid-latitudes."The warming of the Arctic, the polar amplification of warming, plays a key role here," said Mann. "The surface and lower atmosphere are warming more in the Arctic than anywhere else on the globe. That pattern projects onto the very temperature gradient profile that we identify as supporting atmospheric waveguide conditions."Theoretically, standing jet stream waves with large amplitude north/south undulations should cause unusual weather events."We don't trust climate models yet to predict specific episodes of extreme weather because the models are too coarse," said study co-author Dim Coumou of PIK. "However, the models do faithfully reproduce large scale patterns of temperature change," added co-author Kai Kornhuber of PIK.The researchers looked at real-world observations and confirmed that this temperature pattern does correspond with the double-peaked jet stream and waveguide patter associated with persistent extreme weather events in the late spring and summer such as droughts, floods and heat waves. They found the pattern has become more prominent in both observations and climate model simulations."Using the simulations, we demonstrate that rising greenhouse gases are responsible for the increase," said Mann. The researchers noted in today's (Mar. 27) issue of "We are now able to connect the dots when it comes to human-caused global warming and an array of extreme recent weather events," said Mann.While the models do not reliably track individual extreme weather events, they do reproduce the jet stream patterns and temperature scenarios that in the real world lead to torrential rain for days, weeks of broiling sun and absence of precipitation."Currently we have only looked at historical simulations," said Mann. "What's up next is to examine the model projections of the future and see what they imply about what might be in store as far as further increases in extreme weather are concerned."Also working on this project was Sonya K. Miller, programmer analyst, Penn State; and Byron A. Steinman, assistant professor Department of Earth and Environmental Sciences and Large Lakes Observatory, University of Minnesota: Duluth.
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| 2,017 |
March 23, 2017
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https://www.sciencedaily.com/releases/2017/03/170323105824.htm
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Corals die as global warming collides with local weather in the South China Sea
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In the South China Sea, a 2°C rise in the sea surface temperature in June 2015 was amplified to produce a 6°C rise on Dongsha Atoll, a shallow coral reef ecosystem, killing approximately 40 percent of the resident coral community within weeks, according to a study published in
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Wind and waves churn the sea, flushing shallow-water coral reefs with seawater from the open ocean to help them stay cool. But according to new research from the Woods Hole Oceanographic Institution (WHOI), when the weather turns still and these natural cooling mechanisms subside, just a few degrees of ocean warming can prove lethal to the corals that live there.Scientists at WHOI studied this phenomenon in June 2015 while conducting research on Dongsha Atoll, an almost perfectly circular coral reef in the remote South China Sea. The findings, published in the March 24, 2017 issue of the journal "Dongsha Atoll is typically hit with tropical storms and strong winds in June, which keep the corals as cool as the open ocean," said Tom DeCarlo, lead author of the study and a then-graduate student in the MIT-WHOI Joint Program in Oceanography. "But in 2015, the weather in June was exceptionally calm -- at one point, there was basically no wind and no waves. This had an amplifying effect on the water temperatures, which were already feeling the heat from global warming and El Niño. The whole reef became a giant swimming pool that just sat there and baked in the sun."According the DeCarlo, who is now a scientist with the University of Western Australia, it only took a few days of calm winds and waves before the reef lost its supply of cooler water from the open ocean. "We saw water temperatures surge to 36 °C (97 °F) -- a full 6° C above normal summertime temperatures. This caused 100% of the corals to bleach, and 40% of them died," he said.DeCarlo, WHOI scientist Anne Cohen, and dive master Pat Lohmann, witnessed the start of the mass die-off on the last day of their month-long field visit to Dongsha. They had just finished up an ecological survey of coral cover on the reef, and before heading home, jumped in the water to retrieve instruments they use to monitor water temperature, pH and currents. "That's when we saw that all the corals had turned white," said DeCarlo. "We had to catch our flights the next day, but the situation looked dire so Anne sent us back out to the site within a few weeks.According to Cohen, the lead principal investigator on the project, the timing was remarkable given they were still on site when the bleaching started. "It's quite uncommon to be out there in such a remote place as a massive bleaching event is actually happening," said Cohen. "From Tom's surveys, we knew what the healthy reef looked like just before the bleaching, so we could make a direct comparison with the post-bleaching data to assess the effects of the warming."Upon their return, the scientists boated back out to the reef and saw a green tint shimmering through the water -- a possible sign that the corals made it through the bleaching event and were returning to a normal state. But when they dove in, they realized what they had seen was actually green turf algae covering dead corals. "This was the fastest-calcifying reef we've ever studied," said DeCarlo. "So we thought it would have shown resiliency. But everything had come crashing down in the space of a few weeks."The team suspected the amplified warming was due to the weather lull, but they couldn't automatically rule out the possibility that fewer clouds and more sunlight in 2015 versus previous years had caused the event. To test this hypothesis, DeCarlo and co-author Kristen Davis, using data recorded by instruments deployed on the reef, conducted a number of "heat budget" calculations to hone in on the specific factors that drove the extreme heating."We saw that air-to-sea heating mechanisms like sunlight and air temperature had remained nearly constant throughout June, but the wind- and wave-driven currents pushing in cooler offshore water were essentially turned off for a few days. This was the big change that caused the water temperatures to spike on the reef, so our hypothesis was correct -- the unusually calm weather pattern was the primary culprit," said DeCarlo.Water temperatures stabilized in early July as the winds and waves finally kicked up. But the widespread damage had already been done. Given the magnitude of the event, the scientists wanted to know if this reef had experienced similar temperature extremes in the past, and if so, whether the corals recovered. According to Cohen, however, few historical bleaching data existed for the region."This is a super-remote place that takes two hours to get to by plane from mainland Taiwan," she said. There were unpublished accounts of bleaching in 1997, but the severity and extent of that event were not quantified.Without precise historical records, the team drilled core samples from corals living on the reef and used Computed Tomography (CT) scans to look for signals of thermal stress in the past. The scans, which look like an x-rayed mop handle, reveal annual rings or "bands" of varying densities in the coral's skeleton."These bands are like a history book for coral reefs, allowing you to count back in time to specific years and events," said Cohen, who attributes her lab's unique "paleo perspective" to her background in paleo-oceanography. "The brighter, high-density bands, which we call 'stress bands,' are signatures of long and intense bleaching events. Based on cores we scanned, it appears there had been only three previous bleaching events between 1983 and 2015, each of which happened in El Niño years. But we detected very few stress bands in the cores, so while there had been bleaching, these events were not nearly as severe as 2015."Interpreting the CT scan data, DeCarlo says many corals that had bleached in the past appear to have recovered. "The skeletal records show that less than 50 percent of the colonies had bleached during these historical events, which is a stark contrast to the 100 percent bleaching we saw in 2015. This suggests that the area had not seen thermal stress this extreme in the last forty years at least -- maybe even in the last 100 years."The study highlights the consequences for shallow-water coral reefs when global warming intersects with short-lived weather anomalies. But the scientists say their observations also suggest the possibility that climate model projections may underestimate what some coral reefs will experience as the ocean continues to warm over this century."The current global climate models and prognosis for reefs are based on a 2 °C warming scenario for the open ocean," said DeCarlo. "But these projections usually don't account for the kind of regional and local weather anomalies we saw at Dongsha. When you have weather amplification events superimposed on top of carbon dioxide-driven ocean warming, that's when things can get really bad for corals. Models based on open-ocean warming already paint a dire picture for coral reefs, but the scary reality is that they may be too optimistic for many shallow reefs.""Projections based on open-ocean temperatures may not be 100% relevant to these shallow-water environments, where many coral communities live," Cohen added. "It's possible that coral reefs are in much more immediate danger than we have anticipated. When global and regional anomalies align, a seemingly-mild two-degree warming could be more like six degrees."
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| 2,017 |
March 23, 2017
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https://www.sciencedaily.com/releases/2017/03/170323084131.htm
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When air pollution is bad, know how to protect yourself
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The World Health Organization reported this month that pollution and environmental risks are responsible for 1.7 million child deaths per year. Around the world, pollution is constantly taking a toll on our health -- and oz one pollution is especially problematic when the weather gets warmer.
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While cities and states need to implement top-down measures to combat air pollution, those who live in particularly susceptible environments -- like around major roadways -- may not have the luxury of waiting for such changes to take place.Yifang Zhu, professor of environmental health sciences at the UCLA Fielding School of Public Health, says there are steps we can take to protect ourselves and our families from air pollution, which has well-documented negative consequences for childhood asthma, birth outcomes, pregnancy risks, cardiovascular health, and other diseases.Those steps include:
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Weather
| 2,017 |
March 22, 2017
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https://www.sciencedaily.com/releases/2017/03/170322143149.htm
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Sea ice extent sinks to record lows at both poles
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Arctic sea ice appears to have reached on March 7 a record low wintertime maximum extent, according to scientists at NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. And on the opposite side of the planet, on March 3 sea ice around Antarctica hit its lowest extent ever recorded by satellites at the end of summer in the Southern Hemisphere, a surprising turn of events after decades of moderate sea ice expansion.
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On Feb. 13, the combined Arctic and Antarctic sea ice numbers were at their lowest point since satellites began to continuously measure sea ice in 1979. Total polar sea ice covered 6.26 million square miles (16.21 million square kilometers), which is 790,000 square miles (2 million square kilometers) less than the average global minimum extent for 1981-2010 -- the equivalent of having lost a chunk of sea ice larger than Mexico.The ice floating on top of the Arctic Ocean and surrounding seas shrinks in a seasonal cycle from mid-March until mid-September. As the Arctic temperatures drop in the autumn and winter, the ice cover grows again until it reaches its yearly maximum extent, typically in March. The ring of sea ice around the Antarctic continent behaves in a similar manner, with the calendar flipped: it usually reaches its maximum in September and its minimum in February.This winter, a combination of warmer-than-average temperatures, winds unfavorable to ice expansion, and a series of storms halted sea ice growth in the Arctic. This year's maximum extent, reached on March 7 at 5.57 million square miles (14.42 million square kilometers), is 37,000 square miles (97,00 square kilometers) below the previous record low, which occurred in 2015, and 471,000 square miles (1.22 million square kilometers) smaller than the average maximum extent for 1981-2010."We started from a low September minimum extent," said Walt Meier, a sea ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "There was a lot of open ocean water and we saw periods of very slow ice growth in late October and into November, because the water had a lot of accumulated heat that had to be dissipated before ice could grow. The ice formation got a late start and everything lagged behind -- it was hard for the sea ice cover to catch up."The Arctic's sea ice maximum extent has dropped by an average of 2.8 percent per decade since 1979, the year satellites started measuring sea ice. The summertime minimum extent losses are nearly five times larger: 13.5 percent per decade. Besides shrinking in extent, the sea ice cap is also thinning and becoming more vulnerable to the action of ocean waters, winds and warmer temperatures.This year's record low sea ice maximum extent might not necessarily lead to a new record low summertime minimum extent, since weather has a great impact on the melt season's outcome, Meier said. "But it's guaranteed to be below normal."In Antarctica, this year's record low annual sea ice minimum of 815,000 square miles (2.11 million square kilometers) was 71,000 square miles (184,000 square kilometers) below the previous lowest minimum extent in the satellite record, which occurred in 1997.Antarctic sea ice saw an early maximum extent in 2016, followed by a very rapid loss of ice starting in early September. Since November, daily Antarctic sea ice extent has continuously been at its lowest levels in the satellite record. The ice loss slowed down in February.This year's record low happened just two years after several monthly record high sea ice extents in Antarctica and decades of moderate sea ice growth."There's a lot of year-to-year variability in both Arctic and Antarctic sea ice, but overall, until last year, the trends in the Antarctic for every single month were toward more sea ice," said Claire Parkinson, a senior sea ice researcher at Goddard. "Last year was stunningly different, with prominent sea ice decreases in the Antarctic. To think that now the Antarctic sea ice extent is actually reaching a record minimum, that's definitely of interest."Meier said it is too early to tell if this year marks a shift in the behavior of Antarctic sea ice."It is tempting to say that the record low we are seeing this year is global warming finally catching up with Antarctica," Meier said. "However, this might just be an extreme case of pushing the envelope of year-to-year variability. We'll need to have several more years of data to be able to say there has been a significant change in the trend."
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Weather
| 2,017 |
March 22, 2017
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https://www.sciencedaily.com/releases/2017/03/170322143139.htm
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Under the Dead Sea, warnings of dire drought
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Nearly 1,000 feet below the bed of the Dead Sea, scientists have found evidence that during past warm periods, the Mideast has suffered drought on scales never recorded by humans -- a possible warning for current times. Thick layers of crystalline salt show that rainfall plummeted to as little as a fifth of modern levels some 120,000 years ago, and again about 10,000 years ago. Today, the region is drying again as climate warms, and scientists say it will get worse. The new findings may cause them to rethink how much worse, in this already thirsty and volatile part of the world.
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"All the observations show this region is one of those most affected by modern climate change, and it's predicted to get dryer. What we showed is that even under natural conditions, it can become much drier than predicted by any of our models," said lead author Yael Kiro, a geochemist at Columbia University's Lamont-Doherty Earth Observatory. The findings were just published in an early online edition of the journal The landlocked Dead Sea, straddling Israel, Jordan and Palestinian lands, is earth's lowest spot on land. Its current shoreline lies about 1,300 feet below sea level, and its floor extends down another 900 feet. Fed mainly by the Jordan River drainage, which extends also into Syria and Lebanon, it is a dead end for water, and so is extremely salty; its Biblical name in Hebrew is Y?m ha-Melah, the sea of salt. In recent years, its level has dropped about four feet a year. But hot, dry weather is not the main cause yet; rather, booming populations in the region need more water than ever, and people are sucking so much from the watershed, very little reaches the Dead Sea, where evaporation is outweighing input.The U.N. Food and Agriculture Organization estimates that much of the region already has per capita water availability only a tenth of the world average. Rainfall has declined about 10 percent since 1950, and existing climate models say it could sink another 20 percent this century, even as population continues to grow. Israel is meeting demand by desalinating Mediterranean seawater, but poorer, landlocked Jordan and the Palestinian territories are desperate for more. In adjoining Syria, a record 1998-2012 drought likely stoked by climate change is believed to have helped spark the ongoing civil war, which has now claimed more than 500,000 lives and infected neighboring nations.In 2010, scientists from a half-dozen nations drilled 1,500 feet into the deepest part of the seabed, bringing up a cross section of deposits recording 200,000 years of regional climate history -- the longest such archive in the Mideast. (Around-the-clock drilling went for 40 days and 40 nights -- perhaps a respectful bow to the rainfall of the Biblical Flood.) The cores revealed alternating layers of mud washed in with runoff during wet times, and crystallized salt, precipitated out during dry times when the water receded. This instantly made it clear that the region has suffered epic dry periods, but the core was not analyzed in great detail until now.The new study shows that the salt accumulated rapidly?an estimated half-inch per year in many cases. The researchers spotted two striking periods. About halfway down they found salty layers some 300 feet thick, indicating a long-term drop below the sea's current level. This came in a period between ice ages, 115,000 to 130,000 years ago, when variations in Earth's orbit brought temperatures about 4 degrees hotter those of the 20th century?equivalent to what is projected for the end of the 21st century. The lake refilled when glaciers readvanced in sub-polar regions and the Mideast climate cooled and became moister. The cores show a similar drop in lake level just 6,000 to 10,000 years ago, following the most recent ice age, when temperatures were probably a bit cooler than now.The chemistry of tiny fluid bubbles within the salt allowed the researchers to extrapolate rainfall and runoff patterns of these periods. They calculated that runoff to the Dead Sea generally declined 50 to 70 percent compared to today, dwarfing current projections for this century. In the most extreme periods, it went down 80 percent, and this lasted for decades to centuries at a time. The declines are probably linked to broader shifts in atmospheric flow patterns. Storms coming in from the Mediterranean could have slackened, as they appear to be doing today; and then as now, higher temperatures increase evaporation of moisture from the land.To alleviate growing water shortages, Jordan plans to break ground next year on a canal to bring in water from the Red Sea for desalination; leftover brine would be dumped into the Dead Sea, possibly stabilizing its level. But the project is controversial, because it could cause drastic environmental changes in both seas, and could still leave much of the rest of the region with inadequate water."The Dead Sea is wasting away today because humans are using up all its fresh water sources," said Steven Goldstein, a geochemist at Lamont-Doherty and coauthor of the paper who helped oversee the 2010 drilling. "Our study shows that in the past, without any human intervention, the fresh water nearly stopped flowing. This means that if it keeps getting hotter now, it could stop running again. This time, it would affect millions of people."
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Weather
| 2,017 |
March 21, 2017
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https://www.sciencedaily.com/releases/2017/03/170321123641.htm
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Heat exposure associated with mental illness
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A mental hospital-based study in Hanoi, Vietnam looked at if there is a relationship between heat exposure and mental health problems. The results showed significant increase in hospital admissions for mental illnesses during periods of heatwaves, especially during longer periods of heat exposure. This is according to a doctoral thesis from Umeå University.
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The study, which looked at admissions data from the Hanoi Mental Hospital during a 5 year period (2008 -- 2012), also found that factors including old age, gender and rural-dwelling contributed to more mental illness among vulnerable and susceptible groups during heat or extreme heat exposure.According to the results:"I was surprised to find that there were quite strong associations between hospital admissions for depression and other mental disorders and periods of elevated temperatures or heatwaves. The associations grew stronger with the length of the heatwaves and the elderly in particular appeared more sensitive to seasonality, hot weather and heatwaves," says Trang Phan Minh, doctoral student at the Department of Public Health and Clinical Medicine, Epidemiology and Global Health unit, at Umeå University.Trang Phan Minh's study is formative and may pave a way for future studies in Vietnam. According to the researcher, the results can assist mental health professionals in Vietnam by providing more information about the mental health impacts of exposure to weather patterns and extreme heat/heatwave."As the global warming phenomenon emerges and mean temperatures increase, these results showing an association between heat and mental health problems could help Vietnamese policymakers and health managers. This scenario requires good preparedness and solutions for managing a potential increased in mental disorders and for protecting poor populations and poor health groups," says Trang Phan Minh.Trang Phan Minh is a Vietnamese PhD student at the Epidemiology and Global Health unit, Umeå University. She has previously worked for the Institute of Labor Protection in Vietnam as a physician on environmental and occupational health.Link to thesis:
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Weather
| 2,017 |
March 20, 2017
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https://www.sciencedaily.com/releases/2017/03/170320085442.htm
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Transport systems face disruption by extreme weather
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Extreme weather conditions due to climate change pose a new threat to aging infrastructure. We need to be better prepared, according to a publication by the OECD's International Transport Forum. The findings of a number of research projects can now be applied worldwide. VTT Technical Research Centre of Finland was the lead author of the report in Finland.
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Extensive preparations should be made for extreme weather events to minimise or avoid dangerous situations. In an OECD report, experts from a number of countries have broadly appraised the costs of disruption to transport systems and the most effective ways of reducing such costs. The report also included a list of long and short-term strategic measures. The results combine earlier research findings with experiences from the EU, the USA, Canada, Japan and Australia. For example, according to the EWENT (Extreme Weather Impacts on European Networks of Transport) project coordinated by VTT, transport system disruptions alone could cost national economies in the EU up to 0.15% of GDP. Such disruptions include traffic accidents, infrastructure damage, and delays in travel and transport, for example.The freshly published report lists nine strategic measures which it proposes for inclusion in the transport and infrastructure policies of OECD countries. 1) act now! 2) invest in maintenance, 3) prepare for more frequent extreme weather events, 4) draw up continuity plans for sudden events, 5) assess the vulnerability of transport systems, 6) focus on the system's resilience, not just better infrastructure, 7) re-evaluate redundant transport infrastructure, that can provide valuable alternative routes if main routes fail, 8) extend your assessment beyond traditional cost-benefit analyses, 9) develop new investment appraisal methods that take better account of uncertainties, risks and a possible future in which extreme events become more frequent."Each of these recommendations is very serious and they should be taken into account in managing the entire transport system life cycle -- they address planning, construction, appraisal, maintenance and use. Experts need this information when improving the resilience and durability of different parts of the transport system. Citizens will benefit from a transport system that continues to serve the public during extreme weather conditions and situations," emphasises Principal Scientist Pekka Leviäkangas of VTT. "Many impacts of climate change and extreme weather events emerge only after a long delay, so this is not just about sudden phenomena such as torrential rain or snow storms. We need to improve resilience in the long term as well, with an eye on the cost impacts on future generations."A new approach to risk management will also provide new business opportunities to companies involved in maintenance, diagnostics technologies, in the strategic design of the transport system and infrastructure, and life-cycle management.
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Weather
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March 13, 2017
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https://www.sciencedaily.com/releases/2017/03/170313192501.htm
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A scientist and a supercomputer re-create a tornado
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With tornado season fast approaching or already underway in vulnerable states throughout the U.S., new supercomputer simulations are giving meteorologists unprecedented insight into the structure of monstrous thunderstorms and tornadoes. One such recent simulation recreates a tornado-producing supercell thunderstorm that left a path of destruction over the Central Great Plains in 2011.
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The person behind that simulation is Leigh Orf, a scientist with the Cooperative Institute for Meteorological Satellite Studies (CIMSS) at the University of Wisconsin-Madison. He leads a group of researchers who use computer models to unveil the moving parts inside tornadoes and the supercells that produce them. The team has developed expertise creating in-depth visualizations of supercells and discerning how they form and ultimately spawn tornadoes.The work is particularly relevant because the U.S. leads the global tornado count with more than 1,200 touchdowns annually, according to the National Oceanic and Atmospheric Administration.In May 2011, several tornadoes touched down over the Oklahoma landscape in a short, four-day assemblage of storms. One after the other, supercells spawned funnel clouds that caused significant property damage and loss of life. On May 24, one tornado in particular -- the "El Reno" -- registered as an EF-5, the strongest tornado category on the Enhanced Fujita scale. It remained on the ground for nearly two hours and left a path of destruction 63-miles long.Orf's most recent simulation recreates the El Reno tornado, revealing in high-resolution the numerous "mini-tornadoes" that form at the onset of the main tornado. As the funnel cloud develops, they begin to merge, adding strength to the tornado and intensifying wind speeds. Eventually, new structures form, including what Orf refers to as the streamwise vorticity current (SVC)."The SVC is made up of rain-cooled air that is sucked into the updraft that drives the whole system," says Orf. "It's believed that this is a crucial part in maintaining the unusually strong storm, but interestingly, the SVC never makes contact with the tornado. Rather, it flows up and around it."Using real-world observational data, the research team was able to recreate the weather conditions present at the time of the storm and witness the steps leading up to the creation of the tornado. The archived data, taken from a short-term operational model forecast, was in the form of an atmospheric sounding, a vertical profile of temperature, air pressure, wind speed and moisture. When combined in the right way, these parameters can create the conditions suitable for tornado formation, known as tornadogenesis.According to Orf, producing a tornado requires a couple of "non-negotiable" parts, including abundant moisture, instability and wind shear in the atmosphere, and a trigger that moves the air upwards, like a temperature or moisture difference. However, the mere existence of these parts in combination does not mean that a tornado is inevitable."In nature, it's not uncommon for storms to have what we understand to be all the right ingredients for tornadogenesis and then nothing happens," says Orf. "Storm chasers who track tornadoes are familiar with nature's unpredictability, and our models have shown to behave similarly."Orf explains that unlike a typical computer program, where code is written to deliver consistent results, modelling on this level of complexity has inherent variability, and in some ways he finds it encouraging since the real atmosphere exhibits this variability, too.Successful modeling can be limited by the quality of the input data and the processing power of computers. To achieve greater levels of accuracy in the models, retrieving data on the atmospheric conditions immediately prior to tornado formation is ideal, but it remains a difficult and potentially dangerous task. With the complexity of these storms, there can be subtle (and currently unknown) factors in the atmosphere that influence whether or not a supercell forms a tornado.Digitally resolving a tornado simulation to a point where the details are fine enough to yield valuable information requires immense processing power. Fortunately, Orf had earned access to a high-performance supercomputer, specifically designed to handle complex computing needs: the Blue Waters Supercomputer at the National Center for Supercomputing Applications at the University of Illinois at Urbana-ChampaignIn total, their EF-5 simulation took more than three days of run time. In contrast, it would take decades for a conventional desktop computer to complete this type of processing.Looking ahead, Orf is working on the next phase of this research and continues to share the group's findings with scientists and meteorologists across the country. In January 2017, the group's research was featured on the cover of the Bulletin of the American Meteorological Society."We've completed the EF-5 simulation, but we don't plan to stop there," says Orf. "We are going to keep refining the model and continue to analyze the results to better understand these dangerous and powerful systems."
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Weather
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