Climate & Climate Change

High-resolution regional modeling (no supercomputer needed)

Annual precipitation over Colorado as modeled by the low-resolution, global Community Earth System Model (top) compared to the high-resolution, regional Weather Research and Forecasting model (below). (Images courtesy Ethan Gutmann, NCAR.) February 13, 2017 | In global climate models, the hulking, jagged Rocky Mountains are often reduced to smooth, blurry bumps. It's a practical reality that these models, which depict the entire planet, typically need to be run at a relatively low resolution due to constraints on supercomputing resources. But the result, a virtual morphing of peaks into hills, affects the ability of climate models to accurately project how precipitation in mountainous regions may change in the future — information that is critically important to water managers.To address the problem, hydrologists have typically relied on two methods to "downscale" climate model data to make them more useful. The first, which uses statistical techniques, is fast and doesn't require a supercomputer, but it makes many unrealistic assumptions. The second, which uses a high-resolution weather model like the Weather Research and Forecasting model (WRF), is much more realistic but requires vast amounts of computing resources.Now hydrologists at the National Center for Atmospheric Research (NCAR) are developing an in-between option: The Intermediate Complexity Atmospheric Research Model (ICAR) gives researchers increased accuracy using only a tiny fraction of the computing resources."ICAR is about 80 percent as accurate as WRF in the mountainous areas we studied," said NCAR scientist Ethan Gutmann, who is leading the development of ICAR. "But it only uses 1 percent of the computing resources. I can run it on my laptop."Drier mountains, wetter plainsHow much precipitation falls in the mountains — and when — is vitally important for communities in the American West and elsewhere that rely on snowpack to act as a frozen reservoir of sorts. Water managers in these areas are extremely interested in how a changing climate might affect snowfall and temperature, and therefore snowpack, in these regions.But since global climate models with low resolution are not able to accurately represent the complex topography of mountain ranges, they are unsuited for answering these questions.For example, as air flows into Colorado from the west, the Rocky Mountains force that air to rise, cooling it and causing moisture to condense and fall to the ground as snow or rain. Once these air masses clear the mountains, they are drier than they otherwise would have been, so there is less moisture available to fall across Colorado's eastern plains.Low-resolution climate models are not able to capture this mechanism — the lifting of air over the mountains — and so in Colorado, for example, they often simulate mountains that are drier than they should be and plains that are wetter. For a regional water manger, these small shifts could mean the difference between full reservoirs and water shortages."Climate models are useful for predicting large-scale circulation patterns around the whole globe, not for predicting precipitation in the mountains or in your backyard," Gutmann said.Precipitation in millimeters over Colorado between Oct. 1 and May 1 as simulated by the Weather Research and Forecasting model (WRF), the Intermediate Complexity Atmospheric Research model (ICAR), and the observation-based Parameter-Elevation Regressions on Independent Slopes Model. (Images courtesy Ethan Gutmann.)A modeling middle groundA simple statistical fix for these known problems may include adjusting precipitation data to dry out areas known to be too wet and moisten areas known to be too dry. The problem is that these statistical downscaling adjustments don't capture the physical mechanisms responsible for the errors. This means that any impact of a warming climate on the mechanisms themselves would not be accurately portrayed using a statistical technique.That's why using a model like WRF to dynamically downscale the climate data produces more reliable results — the model is actually solving the complex mathematical equations that describe the dynamics of the atmosphere. But all those incredibly detailed calculations also take an incredible amount of computing.A few years ago, Gutmann began to wonder if there was a middle ground. Could he make a model that would solve the equations for just a small portion of the atmospheric dynamics that are important to hydrologists — in this case, the lifting of air masses over the mountains — but not others that are less relevant?"I was studying statistical downscaling techniques, which are widely used in hydrology, and I thought, 'We should be able to do better than this,'" he said. "'We know what happens when you lift air up over a mountain range, so why don’t we just do that?'"Gutmann wrote the original code for the model that would become ICAR in just a few months, but he spent the next four years refining it, a process that's still ongoing.100 times as fastLast year, Gutmann and his colleagues — Martyn Clark and Roy Rasmussen, also of NCAR; Idar Barstad, of Uni Research Computing in Bergen, Norway; and Jeffrey Arnold, of the U.S. Army Corps of Engineers — published a study comparing simulations of Colorado created by ICAR and WRF against observations.The authors found that ICAR and WRF results were generally in good agreement with the observations, especially in the mountains and during the winter. One of ICAR's weaknesses, however, is in simulating storms that build over the plains in the summertime. Unlike WRF, which actually allows storms to form and build in the model, ICAR estimates the number of storms likely to form, given the atmospheric conditions, a method called parameterization.Even so, ICAR, which is freely available to anyone who wants to use it, is already being run by teams in Norway, Austria, France, Chile, and New Zealand."ICAR is not perfect; it's a simple model," Gutmann said. "But in the mountains, ICAR can get you 80 to 90 percent of the way there at 100 times the speed of WRF. And if you choose to simplify some of the physics in ICAR, you can get it close to 1,000 times faster."About the articleTitle: The Intermediate Complexity Atmospheric Research Model (ICAR)Authors: Ethan Gutmann, Idar Barstad, Martyn Clark, Jeffrey Arnold, and Roy RasmussenJournal: Journal of Hydrometeorology, DOI: 10.1175/JHM-D-15-0155.1Funders:U.S. Army Corps of EngineersU.S. Bureau of ReclamationCollaborators:Uni Research Computing in NorwayU.S. Army Corps of EngineersWriter/contact: Laura Snider, Senior Science Writer

Two NCAR scientists honored by American Geophysical Union

BOULDER, Colo. — Martyn Clark, senior scientist at the National Center for Atmospheric Research (NCAR), will be honored next week as a Fellow of the American Geophysical Union (AGU) for his exceptional contribution to Earth science.Clark is an expert in the numerical modeling and prediction of hydrologic processes. His current research includes developing new modeling methods to improve streamflow forecasts and better understand climate change impacts on regional water resources. Clark, who grew up in Christchurch, New Zealand, has authored or co-authored 135 journal articles since receiving his Ph.D. from the University of Colorado in 1998.NCAR Senior Scientist Martyn Clark (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.)"This well-deserved honor reflects Martyn's eminent work in the increasingly critical area of water-resource prediction and management," said NCAR Director James W. Hurrell.Clark said he was delighted to see NCAR's hydrologic modeling recognized. "Hydrology is beginning to play a much stronger role in addressing important interdisciplinary science questions about Earth System change, such as how changes in the terrestrial water cycle affect biological productivity and how groundwater can buffer water stress in ecosystems and human societies. It's exciting to advance modeling capabilities in these areas."NCAR Senior Scientist Bette Otto-Bliesner. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.)Clark is among 60 individuals from eight countries recognized as Fellows this year; only one in one thousand AGU members receive this recognition in any given year. Nearly 40 percent of this year's fellows are from the 110 member colleges and universities of the University Corporation for Atmospheric Research (UCAR), which manages NCAR. This year's class will be honored next Wednesday at the 2016 AGU Fall Meeting in San Francisco.NCAR Senior Scientist Bette Otto-Bliesner, who was named an AGU Fellow last year, is being honored by her peers in the Paleoceanography and Paleoclimatology Focus Group and Ocean Sciences Section by being asked to give the 2016 Emiliani Lecture. She will give the lecture next Wednesday at the AGU Fall Meeting on the topic of "Resolving Some Puzzles of Climate Evolution Since the Last Glacial Maximum: A Melding of Paleoclimate Modeling and Data."The AGU, dedicated to advancing Earth and space sciences for the benefit of society, is a not-for-profit, professional organization representing 60,000 members in more than 140 countries. 

Extreme downpours could increase fivefold across parts of the U.S.

BOULDER, Colo. — At century's end, the number of summertime storms that produce extreme downpours could increase by more than 400 percent across parts of the United States — including sections of the Gulf Coast, Atlantic Coast, and the Southwest — according to a new study by scientists at the National Center for Atmospheric Research (NCAR).The study, published today in the journal Nature Climate Change, also finds that the intensity of individual extreme rainfall events could increase by as much as 70 percent in some areas. That would mean that a storm that drops about 2 inches of rainfall today would be likely to drop nearly 3.5 inches in the future."These are huge increases," said NCAR scientist Andreas Prein, lead author of the study. "Imagine the most intense thunderstorm you typically experience in a single season. Our study finds that, in the future, parts of the U.S. could expect to experience five of those storms in a season, each with an intensity as strong or stronger than current storms."The study was funded by the National Science Foundation (NSF), NCAR's sponsor, and the Research Partnership to Secure Energy for America.“Extreme precipitation events affect our infrastructure through flooding, landslides and debris flows,” said Anjuli Bamzai, program director in NSF’s Directorate for Geosciences, which funded the research.  “We need to better understand how these extreme events are changing. By supporting this research, NSF is working to foster a safer environment for all of us.”The figure shows the expected increase in the number of summertime storms that produce extreme precipitation at century's end compared to the period 2000 - 2013. (©UCAR. Courtesy Andreas Prein, NCAR. This image is freely available for media & nonprofit use.)A year of supercomputing timeAn increase in extreme precipitation is one of the expected impacts of climate change because scientists know that as the atmosphere warms, it can hold more water, and a wetter atmosphere can produce heavier rain. In fact, an increase in precipitation intensity has already been measured across all regions of the U.S. However, climate models are generally not able to simulate these downpours because of their coarse resolution, which has made it difficult for researchers to assess future changes in storm frequency and intensity.For the new study, the research team used a new dataset that was created when NCAR scientists and study co-authors Roy Rasmussen, Changhai Liu, and Kyoko Ikeda ran the NCAR-based Weather Research and Forecasting (WRF) model at a resolution of 4 kilometers, fine enough to simulate individual storms. The simulations, which required a year to run, were performed on the Yellowstone system at the NCAR-Wyoming Supercomputing Center.Prein and his co-authors used the new dataset to investigate changes in downpours over North America in detail. The researchers looked at how storms that occurred between 2000 and 2013 might change if they occurred instead in a climate that was 5 degrees Celsius (9 degrees Fahrenheit) warmer — the temperature increase expected by the end of the century if greenhouse gas emissions continue unabated.Prein cautioned that this approach is a simplified way of comparing present and future climate. It doesn't reflect possible changes to storm tracks or weather systems associated with climate change. The advantage, however, is that scientists can more easily isolate the impact of additional heat and associated moisture on future storm formation."The ability to simulate realistic downpours is a quantum leap in climate modeling. This enables us to investigate changes in hourly rainfall extremes that are related to flash flooding for the very first time," Prein said. "To do this took a tremendous amount of computational resources."Impacts vary across the U.S.The study found that the number of summertime storms producing extreme precipitation is expected to increase across the entire country, though the amount varies by region. The Midwest, for example, sees an increase of zero to about 100 percent across swaths of Nebraska, the Dakotas, Minnesota, and Iowa. But the Gulf Coast, Alabama, Louisiana, Texas, New Mexico, Arizona, and Mexico all see increases ranging from 200 percent to more than 400 percent.The study also found that the intensity of extreme rainfall events in the summer could increase across nearly the entire country, with some regions, including the Northeast and parts of the Southwest, seeing particularly large increases, in some cases of more than 70 percent.A surprising result of the study is that extreme downpours will also increase in areas that are getting drier on average, especially in the Midwest. This is because moderate rainfall events that are the major source of moisture in this region during the summertime are expected to decrease significantly while extreme events increase in frequency and intensity. This shift from moderate to intense rainfall increases the potential for flash floods and mudslides, and can have negative impacts on agriculture.The study also investigated how the environmental conditions that produce the most severe downpours might change in the future. In today's climate, the storms with the highest hourly rainfall intensities form when the daily average temperature is somewhere between 20 and 25 degrees C (68 to 77 degrees F) and with high atmospheric moisture. When the temperature gets too hot, rainstorms become weaker or don't occur at all because the increase in atmospheric moisture cannot keep pace with the increase in temperature. This relative drying of the air robs the atmosphere of one of the essential ingredients needed to form a storm.In the new study, the NCAR scientists found that storms may continue to intensify up to temperatures of 30 degrees C because of a more humid atmosphere. The result would be much more intense storms."Understanding how climate change may affect the environments that produce the most intense storms is essential because of the significant impacts that these kinds of storms have on society," Prein said.About the articleTitle: The future intensification of hourly precipitation extremesAuthors: Andreas F. Prein, Roy M. Rasmussen, Kyoko Ikeda, Changhai Liu, Martyn P. Clark, and Greg J. HollandJournal: Nature Climate Change, DOI: 10.1038/NCLIMATE3168Writer:Laura Snider, Senior Science Writer and Public Information Officer

Days of record-breaking heat ahead

BOULDER, Colo. — If society continues to pump greenhouse gases into the atmosphere at the current rate, Americans later this century will have to endure, on average, about 15 daily maximum temperature records for every time that the mercury notches a record low, new research indicates.That ratio of record highs to record lows could also turn out to be much higher if the pace of emissions increases and produces even more warming, according to the study led by scientists at the National Center for Atmospheric Research (NCAR).Over the last decade, in contrast, the ratio of record high temperatures to record lows has averaged about two to one."More and more frequently, climate change will affect Americans with record-setting heat," said NCAR senior scientist Gerald Meehl, lead author of the new paper. "An increase in average temperatures of a few degrees may not seem like much, but it correlates with a noticeable increase in days that are hotter than any in the record, and nights that will remain warmer than we've ever experienced in the past." The United States has experienced unusual warmth lately, as indicated by this July 22, 2016, weather map showing much of the country facing highs in the 90s and 100s and lows in the 70s. New research indicates that more record high temperatures may be in store. (Weather map by the National Oceanic and Atmospheric Administration's Weather Prediction Center.)The 15-to-1 ratio of record highs to lows is based on temperatures across the continental United States increasing by slightly more than 3 degrees Celsius (5.4 degrees Fahrenheit) above recent years, which is about the amount of warming expected to occur with the current pace of greenhouse gas emissions.The new research appears this week in the "Proceedings of the National Academy of Sciences." It was funded by the Department of Energy (DOE) and the National Science Foundation (NSF), which is NCAR's sponsor. The study was coauthored by NCAR scientist Claudia Tebaldi and by Dennis Adams-Smith, a scientist previously at Climate Central and now at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory.Hotter days  In a 2009 study, Meehl and colleagues found that the ratio of record daily high temperatures to record daily low temperatures has steadily increased since the 1970s as average temperatures over the United States have warmed. Computer models at that time indicated that the ratio could continue to increase during this century, although the research team looked into just one scenario of future emissions. The scientists also found that the models were overstating the ratio of record highs to record lows in recent years, compared to observations.By digging further into the issue and analyzing why the models differed from observations, Meehl and his co-authors have now produced a better calibrated projection of future record-breaking daily highs across the U.S. They based their projections on the average temperature increase over the continental United States, rather than on a particular scenario of future emissions.By about 2065, for example, U.S. temperatures will rise by an average of slightly more than 3 degrees C (5.4 degrees F) if society maintains a “business as usual” increase in the emission of greenhouse gases. Under such a scenario, the ratio of record daily high temperatures to record daily lows will likely be about 15 to 1, although it could range anywhere from 7 to 1 up to 22 to 1, the study found.If temperatures increase even more this century, the ratio of record highs to record lows will jump substantially. For example, if temperatures climb more than 4 degrees C (7.2 degrees F), Americans could experience about 38 record highs for every record low. Such an outcome could occur if society does not make any efforts to mitigate the production of greenhouse gases."Every degree of warming makes a substantial amount of difference, with the ratio of record highs to record lows becoming much greater," Meehl said. "Even with much warmer temperatures on average, we will still have winter and we will still get record cold temperatures, but the numbers of those will be really small compared to record high maximums."If temperatures were not warming, Meehl said, the ratio of record highs to record lows would average out to about one to one.Instead, record high temperatures have already become a common occurrence in much of the country. The ratio of record highs to lows has averaged about 2 to 1 over the first decade of the 21st century, but there is considerable year-to-year variation. The ratio was about 5 to 1 in 2012, dropping to about 1 to 1 in 2013 and 2014, then almost 3 to 1 in 2015. The unusual warmth of 2016, resulting from both climate change and natural patterns such as El Niño, has led to 24,519 record daily maximums vs. 3,970 record daily minimums—a ratio of about 6 to 1.Precipitation and the warm 1930sA key part of the study involved pinpointing why the models in the 2009 study were simulating somewhat more daily record high maximum temperatures compared with recent observations, while there was good agreement between the models and the observed decreases in record low minimums. The authors focused on two sets of simulations conducted on the NCAR-based Community Climate System Model (version 4), which is funded by DOE and NSF and developed by climate scientists across the country.Their analysis uncovered two reasons for the disparity between the computer models and observations.First, the models tended to underestimate precipitation. Because the air is cooled by precipitation and resulting evapotranspiration — the release of moisture from the land and plants back to the atmosphere — the tendency of the computer models to create an overly dry environment led to more record high temperatures.Second, the original study in 2009 only went back to the 1950s. For the new study, the research team also analyzed temperatures in the 1930s and 1940s, which is as far back as accurate recordkeeping will allow. Because the Dust Bowl days of the 1930s were unusually warm, with many record-setting high temperatures, the scientists found that it was more difficult in subsequent years to break those records, even as temperatures warmed. However, even taking the warm 1930s into account, both the model-simulated and observed ratio of record highs to record lows have been increasing."The steady increase in the record ratio is an immediate and stark reminder of how our temperatures have been shifting and continue to do so, reaching unprecedented highs and fewer record lows," said Tebaldi. "These changes pose adaptation challenges to both human and natural systems. Only a substantial mitigation of greenhouse gas emissions may stop this increase, or at least slow down its pace."About the articleTitle: "US daily temperature records past, present, and future"Authors: Gerald A. Meehl, Claudia Tebaldi, and Dennis Adams-SmithJournal: Proceedings of the National Academy of Sciences

Applying indigenous and Western knowledge to environmental research

November 3, 2016 | Native American researchers, students, and community members will partner with Western science organizations to help shape mutually beneficial research projects as part of a two-year National Science Foundation grant awarded recently to the University Corporation for Atmospheric Research. UCAR manages the National Center for Atmospheric Research (NCAR) under sponsorship by NSF.The project marks a milestone in collaborations between NCAR|UCAR and Native American partners to increase the presence of indigenous perspectives and participants in geoscience research. It also comes at a time when indigenous people are among the hardest-hit by climate change, with several communities forming America's first wave of climate refugees.Aimed at building research partnerships between Native American and Western scientists, the NCAR|UCAR project has two supporting goals: broadening career paths for Native American students interested in Earth system science, and increasing the cultural sensitivity of Western scientists. Other partners in the project include the NCAR-based Rising Voices program, Haskell Indian Nations University, the University of Arizona's Biosphere 2, Michigan State University, and the GLOBE citizen science program conducted by the UCAR-based Global Learning and Observations to Benefit the Environment."It's an exciting opportunity for both young indigenous scientists and scientists at NCAR and Biosphere 2," said Carolyn Brinkworth, NCAR director of Diversity, Education, and Outreach, and principal investigator of the project. "It's also a very different way of thinking about the science - truly integrating indigenous and traditional Western practices to benefit all of our partners."For example, she noted, indigenous communities can contribute important information about climate change by bringing generations of knowledge and experience with resource management and environmental and ecological processes.Students attending the Rising Voices workshop in Waimea, Hawaii, in 2016, visited a food garden planted according to traditional Hawaiian techniques to learn about climate change and phenology – the study of the seasonality of plants and animals. (Photo courtesy Craig Elevitch.)The pilot project is one of 37 awarded nationwide as part of a new NSF program called INCLUDES (Inclusion across the Nation of Communities of Learners of Underrepresented Discoverers in Engineering and Science). The program aspires to make careers in science, technology, engineering, and mathematics (STEM) more accessible to underserved populations.Two students from tribal colleges and universities will be selected to become interns in UCAR's SOARS program (Significant Opportunities in Atmospheric Research and Science). The students will join research teams comprised of mentors from NCAR, Biosphere 2, and their home communities to co-develop their research projects.One of the project partners, the four-year-old Rising Voices program, has brought social and physical scientists and engineers together with Native American community members to build bonds that lead to research collaboration."The INCLUDES project will actualize many topics we've been talking about in Rising Voices," said Heather Lazrus, an NCAR environmental anthropologist and Rising Voices co-founder. "The project will create a pathway for the students to become engaged in atmospheric sciences at a young age through a citizen science component, and then help keep them engaged for the long haul.”The GLOBE citizen science component will help the SOARS students reach out to their communities through a number of activities, especially with middle- and high-school students. The project also will connect community youth with undergraduate programs at Haskell and the University of Arizona.As it does for all its interns, SOARS will provide multiple mentors to help the Native American students develop their research, computer modeling, scientific communication, and professional skills.SOARS Director Rebecca Haacker said the internship program has brought in students from Haskell before. “But this will enable us to expand our relationship with indigenous students, and it's nice to see the student internships being part of this larger effort.”The mentors will be supported with cultural training by Michigan State University professor Kyle Powys Whyte, who is also a member of Rising Voices. "We don't want a situation of Western scientists working with Native Americans without any preparation," Brinkworth said. "We want the Western scientists to be introduced to the students' culture, their ways of thinking, their ways of working."The plan is for two SOARS interns to be selected by early 2017 and participate in research projects over the summer. In a second phase, NSF plans to bring together all the pilot projects two years from now with the goal of building out a comprehensive “Alliance” program.Brinkworth said that when she saw the request for proposals, she thought NCAR was uniquely positioned, in part because of Rising Voices, which has strengthened relationships among participating scientists and Native American communities.She hopes the new pilot project and the lessons to be learned will become a template for other efforts. "We are trying to produce a model for other Western scientific organizations that want to partner with indigenous scientists and communities," she said.Writer/contactJeff Smith, Science Writer and Public Information Officer 

40 Earths: NCAR's Large Ensemble reveals staggering climate variability

Sept. 29, 2016 | Over the last century, Earth's climate has had its natural ups and downs. Against the backdrop of human-caused climate change, fluctuating atmosphere and ocean circulation patterns have caused the melting of Arctic sea ice to sometimes speed up and sometimes slow down, for example. And the back-and-forth formation of El Niño and La Niña events in the Pacific has cause d some parts of the world to get wetter or drier while some parts get warmer or cooler, depending on the year.But what if the sequence of variability that actually occurred over the last century was just one way that Earth's climate story could have plausibly unfolded? What if tiny — even imperceptible — changes in Earth's atmosphere had kicked off an entirely different sequence of naturally occurring climate events?"It's the proverbial butterfly effect," said Clara Deser, a senior climate scientist at the National Center for Atmospheric Research (NCAR). "Could a butterfly flapping its wings in Mexico set off these little motions in the atmosphere that cascade into large-scale changes to atmospheric circulation?"To explore the possible impact of miniscule perturbations to the climate — and gain a fuller understanding of the range of climate variability that could occur — Deser and her colleague Jennifer Kay, an assistant professor at the University of Colorado Boulder and an NCAR visiting scientist, led a project to run the NCAR-based Community Earth System Model (CESM) 40 times from 1920 forward to 2100. With each simulation, the scientists modified the model's starting conditions ever so slightly by adjusting the global atmospheric temperature by less than one-trillionth of one degree, touching off a unique and chaotic chain of climate events.The result, called the CESM Large Ensemble, is a staggering display of Earth climates that could have been along with a rich look at future climates that could potentially be."We gave the temperature in the atmosphere the tiniest tickle in the model — you could never measure it — and the resulting diversity of climate projections is astounding," Deser said. "It's been really eye-opening for people."The dataset generated during the project, which is freely available, has already proven to be a tremendous resource for researchers across the globe who are interested in how natural climate variability and human-caused climate change interact. In a little over a year, about 100 peer-reviewed scientific journal articles have used data from the CESM Large Ensemble.Winter temperature trends (in degrees Celsius) for North America between 1963 and 2012 for each of 30 members of the CESM Large Ensemble. The variations in warming and cooling in the 30 members illustrate the far-reaching effects of natural variability superimposed on human-induced climate change. The ensemble mean (EM; bottom, second image from right) averages out the natural variability, leaving only the warming trend attributed to human-caused climate change. The image at bottom right (OBS) shows actual observations from the same time period. By comparing the ensemble mean to the observations, the science team was able to parse how much of the warming over North America was due to natural variability and how much was due to human-caused climate change. Read the full study in the American Meteorological Society's Journal of Climate. (© 2016 AMS.) A community effortRunning a complex climate model like the CESM several dozen times takes a vast amount of computing resources, which makes such projects rare and difficult to pull off. With that in mind, Deser and Kay wanted to make sure that the data resulting from the Large Ensemble were as useful as possible. To do that, they queried scientists from across the community who might make use of the project results — oceanographers, geochemists, atmospheric scientists, biologists, socioeconomic researchers — about what they really wanted."It took a village to make this ensemble happen and for it to be useful to and usable by the broad climate community," Kay said. "The result is a large number of ensemble members, in a state-of-the-art climate model, with outputs asked for by the community, that is publicly available and relatively easy to access — it's no wonder it's getting so much use."Scientists have so far relied on the CESM Large Ensemble to study everything from oxygen levels in the ocean to potential geoengineering scenarios to possible changes in the frequency of moisture-laden atmospheric rivers making landfall. In fact, so many researchers have found the Large Ensemble so useful that Kay and Deser were honored with the 2016 CESM Distinguished Achievement Award, which recognizes significant contributions to the climate modeling community.The award citation noted the pair was chosen because "the Large Ensemble represents one of NCAR's most significant contributions to the U.S. climate research community. … At a scientific level, the utility of the Large Ensemble cannot be overstated."The power of multiple runs: Looking forward — and backwardClearly, the CESM Large Ensemble is useful for looking forward: What is the range of possible futures we might expect in the face of a changing climate? How much warmer will summers become? When will summer Arctic sea ice disappear? How will climate change affect ocean life?But the Large Ensemble is also an extremely valuable tool for understanding our past. This vast storehouse of data helps scientists evaluate observations and put them in context: How unusual is a particular heat wave? Is a recent change in rainfall patterns the result of global warming or could it be from solely natural causes?With only a single model run, scientists are limited in what they can conclude when an observation doesn't match up with a model's projection. For example, if the Arctic sea ice extent were to expand, even though the model projected a decline, what would that mean? Is the physics underlying the model wrong? Or does the model incorrectly capture the natural variability? In other words, if you ran the model more times, with slightly different starting conditions, would one of the model runs correctly project the growth in sea ice?The Large Ensemble helps answer that question. Armed with 40 different simulations, scientists can characterize the range of historic natural variability. With this information, they can determine if observations fit within the envelope of natural variability outlined in the model, instead of comparing them to a single run.Creating an envelope of what can be considered natural also makes it possible to see when the signal of human-caused climate change has pushed an observation beyond the natural variability. The Large Ensemble can also clarify the climate change "signal" in the model. That's because averaging together the 40 ensemble members can effectively cancel out the natural variability — a La Niña in one model run might cancel out an El Niño in another, for example — leaving behind only changes due to climate change."This new ability to separate natural internal variability from externally driven trends is absolutely critical for moving forward our understanding of climate and climate change," said Galen McKinley, a professor of atmospheric and oceanic sciences at the University of Wisconsin–Madison.McKinley used the Large Ensemble — which she called a "transformative tool" — to study changes in the ocean's ability to take up carbon dioxide in a warming climate.The two components of the climate systemThe CESM Large Ensemble is not the first ensemble of climate simulations, though it is perhaps the most comprehensive and widely used. Scientists have long understood that it makes sense to look at more than one model run. Frequently, however, scientists have done this by comparing simulations from different climate models, collectively called a multi-model ensemble.This method gives a feel for the diversity of possible outcomes, but it doesn't allow researchers to determine why two model simulations might differ: Is it because the models themselves represent the physics of the Earth system differently? Or is it because the models have different representations of the natural variability or different sensitivities to changing carbon dioxide concentrations?The Large Ensemble helps resolve this dilemma. Because each member is run using the same model, the differences between runs can be attributed to differences in natural variability alone. The Large Ensemble also offers context for comparing simulations in a multi-model ensemble. If the simulations appear to disagree about what the future may look like—but they still fit within the envelope of natural variability characterized by the Large Ensemble—that could be a clue that the models do not actually disagree on the fundamentals. Instead, they may just be representing different sequences of natural variability.This ability to put model results in context is important, not just for scientists but for policy makers, according to Noah Diffenbaugh, a climate scientist at Stanford University who has used the Large Ensemble in several studies, including one that looks at the contribution of climate change to the recent, severe California drought.“It’s pretty common for real-world decision makers to look at the different simulations from different models, and throw up their hands and say, 'These models don't agree so I can't make decisions,'" he said. "In reality, it may not be that the models are disagreeing. Instead, we may be seeing the actual uncertainty of the climate system. There is some amount of natural uncertainty that we can't reduce — that information is really important for making robust decisions, and the Large Ensemble is giving us a window that we haven’t had before.”Deser agrees that it's important to communicate to the public that, in the climate system, there will always be this "irreducible" uncertainty."We’re always going to have these two components to the climate system: human-induced changes and natural variability. You always have to take both into account," Deser said. "In the future, it will all depend on how the human-induced component is either offset — or augmented — by the sequence of natural variability that unfolds."About the articleTitle: The Community Earth System Model (CESM) Large Ensemble Project: A Community Resource for Studying Climate Change in the Presence of Internal Climate VariabilityAuthors:  J. E. Kay, C. Deser, A. Phillips, A. Mai, C. Hannay, G. Strand, J. M. Arblaster, S. C. Bates, G. Danabasoglu, J. Edwards, M. Holland, P. Kushner, J.-F. Lamarque, D. Lawrence, K. Lindsay, A. Middleton, E. Munoz, R. Neale, K. Oleson, L. Polvani, and M. VertensteinJournal: Bulletin of the American Meteorological Society, DOI: 10.1175/BAMS-D-13-00255.1Funders: National Science FoundationU.S. Department of EnergyIn the news: Stories about research using the CESM Large EnsembleCauses of California drought linked to climate change, Stanford scientists sayStanford University (UCAR Member)The difficulty of predicting an ice-free ArcticUniversity of Colorado Boulder (UCAR Member)Widespread loss of ocean oxygen to become noticeable in 2030sNCARCornell Scientist Predicts Climate Change Will Prompt Earlier Spring Start DateCornell University (UCAR Member)The 2-degree goal and the question of geoengineeringNCAR New climate model better predicts changes to ocean-carbon sinkUniversity of Wisconsin Madison (UCAR Member)Future summers could regularly be hotter than the hottest on recordNCARExtreme-Weather Winters Becoming More CommonStanford (UCAR Member)More frequent extreme precipitation ahead for western North AmericaPacific Northwest National LaboratoryCloudy With A Chance of WarmingUniversity of Colorado Boulder (UCAR Member)Climate change already accelerating sea level rise, study finds NCARLess ice, more water in Arctic Ocean by 2050s, new CU-Boulder study findsUniversity of Colorado Boulder (UCAR Member)California 2100: More frequent and more severe droughts and floods likelyPacific Northwest National Laboratory Searing heat waves detailed in study of future climateNCAR Did climate change, El Nino make Texas floods worse?Utah State University (UCAR Member)Writer/contact:Laura Snider, Senior Science Writer and Public Information Officer

Food security report wins USDA award

BOULDER, Colo. — A comprehensive report warning of the impacts of climate change on the world's food security has won a top U.S. Department of Agriculture (USDA) award."Climate Change, Global Food Security, and the U.S. Food System," with co-authors from the National Center for Atmospheric Research (NCAR), provides an overview of recent research in climate change and agriculture. It warns that warmer temperatures and altered precipitation patterns can threaten food production, disrupt transportation systems, and degrade food safety, among other impacts, and that the world's poor and those living in tropical regions are particularly vulnerable.Michael Scuse, USDA acting deputy secretary (center), with members of the team of experts who produced the award-winning report, "Climate Change, Global Food Security, and the U.S. Food System." Those pictured are (back row from left): William Easterling (The Pennsylvania State University), Edward Carr (Clark University), and Peter Backlund (Colorado State University); front row from left: Rachel Melnick (USDA), Margaret Walsh (USDA), Scuse, Moffat Ngugi (U.S. Agency for International Development/USDA), and Karen Griggs (NCAR). (Photo by USDA.) The USDA this month named it as the winner of the 2016 Abraham Lincoln Honor Award for Increasing Global Food Security. The Abraham Lincoln Honor Award is the most prestigious USDA award presented by the Secretary of Agriculture, recognizing noteworthy accomplishments that significantly contribute to the advancement of the USDA's strategic goals, mission objectives, and overall management excellence.The report was produced as part of a collaboration between NCAR, the USDA, and the University Corporation for Atmospheric Research (UCAR), which manages NCAR on behalf of the National Science Foundation. It was written by 32 experts from 19 federal, academic, nongovernmental, intergovernmental, and private organizations in the United States, Argentina, Britain, and Thailand. The authors included three NCAR scientists, as well as eight experts affiliated with UCAR member universities."This award highlights the importance of addressing climate change in order to maintain the progress the world has made on food security in recent decades," said NCAR program director Lawrence Buja, who helped oversee production of the report. "Scientists will continue to study this critical issue and work with decision makers to co-develop the information they need about potential climate impacts on future production, distribution, and other aspects of our U.S. and global food systems."Published under the auspices of the U.S. Global Change Research Program, the reportfocuses on identifying climate change impacts on global food security through 2100. The authors emphasize that food security — the ability of people to obtain and use sufficient amounts of safe and nutritious food — will be affected by several factors in addition to climate change, such as technological advances, increases in population, the distribution of wealth, and changes in eating habits."Climate change has a myriad of potential impacts, especially on food, water, and energy systems," said UCAR President Antonio J. Busalacchi. "I commend the authors of this report for clearly analyzing this very complex issue in the agriculture sector, which has implications for all of society, from the least developed nations to the most advanced economies."Report authorsMolly Brown, University of Maryland*John Antle, Oregon State University*Peter Backlund, Colorado State University *Edward Carr, Clark UniversityBill Easterling, Pennsylvania State University*Margaret Walsh, USDA Office of the Chief Economist/Climate Change Program OfficeCaspar Ammann, NCARWitsanu Attavanich, Kasetsart UniversityChris Barrett, Cornell University*Marc Bellemare, University of Minnesota*Violet Dancheck, U.S. Agency for International DevelopmentChris Funk, U.S. Geological SurveyKathryn Grace, University of Utah*John Ingram, University of OxfordHui Jiang, USDA Foreign Agricultural ServiceHector Maletta, Universidad de Buenos AiresTawny Mata, USDA/American Association for the Advancement of ScienceAnthony Murray, USDA-Economic Research ServiceMoffatt Ngugi, U.S. Agency for International Development/USDA Foreign Agricultural ServiceDennis Ojima, Colorado State University*Brian O'Neill, NCARClaudia Tebaldi, NCAR*UCAR member universityReport project teamLawrence Buja, NCARKaren Griggs, NCAR 

Atmospheric rivers come into focus with high-res climate model

A high-resolution climate model based at the National Center for Atmospheric Research (NCAR) is able to accurately capture the ribbons of moist air that sometimes escape the sodden tropics and flow toward the drier mid-latitudes, allowing scientists to investigate how "atmospheric rivers" may change as the climate warms. These rivers in the sky can unleash drenching rains when they crash onto land. Because these downpours can alleviate droughts and also cause damaging floods, scientists are keenly interested in how their frequency, intensity, or path may be altered with climate change. But standard-resolution climate models have had difficulty realistically simulating atmospheric rivers and their impacts.In a pair of studies published this summer in the journal Geophysical Research Letters, NCAR scientists Christine Shields and Jeffrey Kiehl tested to see if a high-resolution climate model could do a better job. They found that a version of the NCAR-based Community Climate System Model 4.0 (CCSM4) with a resolution twice as high as normal does a good job of capturing the frequency with which atmospheric rivers made landfall over the last century as well as their locations and associated storms.Satellite images of water vapor over the oceans show atmospheric rivers known as the Pineapple Express hitting the U.S. West Coast in 2006 (top), 2009 (middle), and 2004 (bottom). (Images courtesy of NOAA.) Looking forward, the model projects that storms on the U.S. West Coast associated with a type of atmospheric river called the Pineapple Express, which sweeps moisture in from Hawaii, could linger and become more intense if greenhouse gas emissions are not mitigated.The studies also find that future changes to atmospheric rivers in general — including a possible increase in the number that make landfall in Southern California — will likely be dependent on how jet streams change in a warming world."Atmospheric rivers play an extremely important role in the Earth's water cycle. At any latitude, they account for only 10 percent of the air but they transport as much as 90 percent of the water that is moving from the tropics toward the poles," Kiehl said. "Understanding atmospheric rivers is critical to understanding how the entire climate system works."The how and why of future changesAtmospheric rivers were first discovered in the 1990s, and much of the early research was focused at understanding their detailed structure and the dynamics of how they form."We've gotten to a point in the science where we're able to track atmospheric rivers and detect them fairly well, and we can make some general statements about duration, intensity, and the precipitation associated with them," Shields said. "So the next step is really trying to understand how they might change in the future and, then, why they are changing."Shields and Kiehl suspected that the high-resolution version of the CCSM4 would be useful for answering those questions for a couple of reasons. Because the model has a resolution of about 50 kilometers (31 miles), it does a better job of capturing narrower phenomena, like the rivers. It also represents the complex terrain on the land surface that can trigger the atmospheric rivers to release rain or snow. As the rivers plow into the mountains of California, for example, they're forced higher into the atmosphere, where the moisture condenses and falls to the ground.As they'd hoped, the model did do a better job than a standard-resolution climate model at representing both the atmospheric rivers and their interactions with terrain. This allowed them to run the model forward to get a look at what rivers might do in the future if human-caused climate change continues unabated. What they found is that how — and why — atmospheric rivers change depends on the area of the world."Changes to atmospheric rivers in the future track with what the jets are doing," Shields said. "And that depends on your region."For example, the scientists found that the atmospheric rivers that hit California were influenced by changes to the subtropical jet, while atmospheric rivers that hit the United Kingdom were influenced by the polar jet.While understanding these connections gives scientist important insight into what factors may impact atmospheric rivers in the future, it's still a challenge for scientists to project how atmospheric rivers may actually change. That's because climate models tend to disagree about how jets will shift regionally as the climate warms.In the future, Shields and Kiehl plan to expand their analysis to other parts of the world, including the Iberian Peninsula."The climate change picture and what's going to happen to these atmospheric rivers really matter," Shields said. "They are a critical component of the hydrology in many places in the world."About the papers: Titles: "Simulating the Pineapple Express in the half degree Community Climate System Model, CCSM4," and "Atmospheric River Landfall-Latitude Changes in Future Climate Simulations"Authors: Christine A. Shields and Jeffrey T. KiehlJournal: Geophysical Research Letters, DOIs: 10.1002/2016GL069476 and 10.1002/2016GL070470Funders:National Science FoundationU.S. Department of EnergyWriter/contact:Laura Snider, Senior Science Writer and Public Information Officer 

The 2-degree goal and the question of geoengineering

Sept. 7, 2016 | With world leaders agreeing to try to limit the increase in global temperatures, scientists at the National Center for Atmospheric Research (NCAR) are taking a look at whether geoengineering the climate could counter enough warming to help meet that goal. In a new study, the scientists found that if society doesn't make steep cuts in greenhouse gas emissions in the next couple of decades, injections of planet-cooling sulfates into the atmosphere could theoretically limit warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels. But such geoengineeing would mean a sustained effort stretching over more than a century and a half, and it would fail to prevent certain aspects of climate change."One thing that surprised me about this study is how much geoengineering it would take to stay within 2 degrees if we don't start reducing greenhouse gases soon," said NCAR scientist Simone Tilmes, the lead author.For the study, the research team focused on the potential impacts of geoengineering on temperatures, the drying of land surfaces, and Arctic sea ice. They did not examine possible adverse environmental consequences such as potential damage to the ozone layer. The sulfate injections also would not alleviate the impact of carbon dioxide emissions on ocean acidification.The research was published in the journal Geophysical Research Letters.Meeting an ambitious targetRepresentatives of 195 nations negotiated last fall's Paris Agreement, which sets an ambitious target of capping global warming at no more than 2 degrees. Scientists have found, however, that such a target will be extremely difficult to achieve. It would require society to begin dramatically reducing emissions of carbon dioxide and other greenhouse gases within a few years. Efforts to develop new technologies that could draw down carbon dioxide from the atmosphere would also be needed to succeed.Volcanic eruptions spew sulfates into the air, which can block incoming sunlight and have a cooling effect on the planet. One type of proposed geoengineering would rely on a similar method: injecting sulfates high in the atmopshere to try to cool the Earth. (Image courtesy of USGS.)The new study examined a scenario in which emissions continue growing at current rates until about 2040, when warming would reach 2 degrees. The authors found that, even if society then adopted an aggressive approach to reducing emissions and was able to begin drawing down carbon dioxide from the atmosphere, warming would reach 3 degrees by the end of the century.So they explored an additional possibility: injecting sulfate particles, like those emitted during volcanic eruptions, into the stratosphere. This approach to geoengineering, which is untested but has generated discussion for several years, would theoretically counter global warming because the sulfates would block incoming sunlight and shade the planet. This is why large volcanic eruptions can have a planet-cooling effect.The research team estimated that society would need to keep injecting sulfates for 160 years to stay within the target of 2 degrees. This would require a peak rate of 18 megatons of sulfur dioxide per year, or about 1.5 times the amount emitted by the massive eruption of Mt. Pinatubo in 1992.A different climateEven so, the climate would be noticeably altered under this scenario. Extreme hot days with geoengineering would be about twice as frequent in North America and other regions compared to present-day conditions. (In comparison, they would be about five to six times more frequent without geoengineering.) Summertime Arctic sea ice would retreat significantly with geoengineering, whereas it would disappear altogether if society relied solely on reducingcarbon dioxide in the atmosphere after 2040. Precipitation patterns would also change with geoengineering, causing drying in some regions."If society doesn't act quickly on emissions, we may be facing more uncertain methods like geoengineering to keep temperatures from going over the 2-degree target," Tilmes said. "But even with geoengineering, we'd still be looking at a climate that's different than today's. For the study, Tilmes and her colleagues used a pair of computer models: the NCAR-based Community Earth System Model and the Integrated Science Assessment Model at the University of Illinois. These enabled the authors to simulate climate conditions with different levels of greenhouse gases as well as stratospheric sulfates.The research was supported by the National Science Foundation and the Department of Energy.About the article:Title: Climate impacts of geoengineering in a delayed mitigation scenarioAuthors: Simone Tilmes, Benjamin Sanderson, and Brian O'NeillJournal: Geophysical Research Letters, DOI: 10.1002/2016gl070122Funders:National Science FoundationU.S. Department of EnergyWriter/contact:David Hosansky, Manager of Media Relations

Climate change already accelerating sea level rise, study finds

BOULDER, Colo. — Greenhouse gases are already having an accelerating effect on sea level rise, but the impact has so far been masked by the cataclysmic 1991 eruption of Mount Pinatubo in the Philippines, according to a new study led by the National Center for Atmospheric Research (NCAR).Satellite observations, which began in 1993, indicate that the rate of sea level rise has held fairly steady at about 3 millimeters per year. But the expected acceleration due to climate change is likely hidden in the satellite record because of a happenstance of timing: The record began soon after the Pinatubo eruption, which temporarily cooled the planet, causing sea levels to drop.The new study finds that the lower starting point effectively distorts the calculation of sea level rise acceleration for the last couple of decades.The study lends support to climate model projections, which show the rate of sea level rise escalating over time as the climate warms. The findings were published today in the open-access Nature journal Scientific Reports.Mount Pinatubo's caldera on June 22, 1991. (Image courtesy USGS.)"When we used climate model runs designed to remove the effect of the Pinatubo eruption, we saw the rate of sea level rise accelerating in our simulations," said NCAR scientist John Fasullo, who led the study. "Now that the impacts of Pinatubo have faded, this acceleration should become evident in the satellite measurements in the coming decade, barring another major volcanic eruption."Study co-author Steve Nerem, from the University of Colorado Boulder, added: “This study shows that large volcanic eruptions can significantly impact the satellite record of global average sea level change. So we must be careful to consider these effects when we look for the effects of climate change in the satellite-based sea level record."The findings have implications for the extent of sea level rise this century and may be useful to coastal communities planning for the future. In recent years, decision makers have debated whether these communities should make plans based on the steady rate of sea level rise measured in recent decades or based on the accelerated rate expected in the future by climate scientists.The study was funded by NASA, the U.S. Department of Energy, and the National Science Foundation, which is NCAR's sponsor.Reconstructing a pre-Pinatubo worldClimate change triggers sea level rise in a couple of ways: by warming the ocean, which causes the water to expand, and by melting glaciers and ice sheets, which drain into the ocean and increase its volume. In recent decades, the pace of warming and melting has accelerated, and scientists have expected to see a corresponding increase in the rate of sea level rise. But analysis of the relatively short satellite record has not borne that out.To investigate, Fasullo, Nerem, and Benjamin Hamlington of Old Dominion University worked to pin down how quickly sea levels were rising in the decades before the satellite record began.Prior to the launch of the international TOPEX/Poseidon satellite mission in late 1992, sea level was mainly measured using tide gauges. While records from some gauges stretch back to the 18th century, variations in measurement technique and location mean that the pre-satellite record is best used to get a ballpark estimate of global mean sea level.Mount Pinatubo erupting in 1991. (Image courtesy USGS.)To complement the historic record, the research team used a dataset produced by running the NCAR-based Community Earth System Model 40 times with slightly different—but historically plausible—starting conditions. The resulting simulations characterize the range of natural variability in the factors that affect sea levels. The model was run on the Yellowstone system at the NCAR-Wyoming Supercomputing Center.A separate set of model runs that omitted volcanic aerosols — particles spewed into the atmosphere by an eruption — was also assessed. By comparing the two sets of runs, the scientists were able to pick out a signal (in this case, the impact of Mount Pinatubo's eruption) from the noise (natural variations in ocean temperature and other factors that affect sea level)."You can't do it with one or two model runs—or even three or four," Fasullo said. "There's just too much accompanying climate noise to understand precisely what the effect of Pinatubo was. We could not have done it without large numbers of runs."Using models to understand observationsAnalyzing the simulations, the research team found that Pinatubo's eruption caused the oceans to cool and sea levels to drop by about 6 millimeters immediately before TOPEX/Poseidon began recording observations.As the sunlight-blocking aerosols from Mount Pinatubo dissipated in the simulations, sea levels began to slowly rebound to pre-eruption levels. This rebound swamped the acceleration caused by the warming climate and made the rate of sea level rise higher in the mid- to late 1990s than it would otherwise have been.This higher-than-normal rate of sea level rise in the early part of the satellite record makes it appear that the rate of sea level rise has not accelerated over time and may actually have decreased somewhat. In fact, according to the study, if the Pinatubo eruption had not occurred—leaving sea level at a higher starting point in the early 1990s—the satellite record would have shown a clear acceleration."The satellite record is unable to account for everything that happened before the first satellite was launched, " Fasullo said. "This study is a great example of how computer models can give us the historical context that's needed to understand some of what we're seeing in the satellite record."Understanding whether the rate of sea level rise is accelerating or remaining constant is important because it drastically changes what sea levels might look like in 20, 50, or 100 years.“These scientists have disentangled the major role played by the 1991 volcanic eruption of Mt. Pinatubo on trends in global mean sea level,” said Anjuli Bamzai, program director in the National Science Foundation’s Division of Atmospheric and Geospace Sciences, which funded the research.  “This research is vital as society prepares for the potential effects of climate change."Because the study's findings suggest that acceleration due to climate change is already under way, the acceleration should become evident in the satellite record in the coming decade, Fasullo said.Since the original TOPEX/Poseidon mission, other satellites have been launched—Jason-1 in 2001 and Jason-2 in 2008—to continue tracking sea levels. The most recent satellite, Jason-3, launched on Jan. 17 of this year."Sea level rise is potentially one of the most damaging impacts of climate change, so it's critical that we understand how quickly it will rise in the future," Fasullo said. "Measurements from Jason-3 will help us evaluate what we've learned in this study and help us better plan for the future."The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.The graph shows how sea level rises and falls as ocean heat content fluctuates. After volcanic eruptions, the Earth cools and, in turn, the heat content in the ocean drops, ultimately lowering sea level.The solid blue line is the average sea level rise of climate model simulations that include volcanic eruptions. The green line is the average from model simulations with the effect of volcanic eruptions removed, and it shows a smooth acceleration in the rate of sea level rise due to climate change.The blue line between the start of the satellite record and present day makes a relatively straight line — just as we see from actual satellite observations during that time —  indicating that the rate of sea level rise has not accelerated. But in the future, barring another major volcanic eruption, scientists expect sea level to follow the gray dotted line, which is on the same accelerating path as the green line below it. Click to enlarge. (©UCAR. This graph is freely available for media & nonprofit use.) About the articleTitle: Is the detection of sea level rise imminent?Authors: J.T. Fasullo, R. S. Nerem, and B. HamlingtonJournal: Scientific Reports, DOI: 10.1038/srep31245 Funders:  NASANational Science FoundationU.S. Department of Energy Collaborators: Univesity of Colorado Boulder (UCAR member)Old Dominion University (UCAR member)Writer:Laura Snider, Senior Science Writer and Public Information Officer

Pages

Subscribe to Climate & Climate Change