Policy & Society

Capping warming at 2 degrees

June 27, 2016 | Even if countries adhere to the Paris climate agreement hammered out last fall, capping global warming at 2 degrees Celsius would likely require net zero greenhouse gas emissions by 2085 and substantial negative emissions over the long term, according to an in-depth analysis by scientists at the National Center for Atmospheric Research (NCAR). More than 100 parties to the Paris Agreement submitted pledges to the United Nations Framework Convention on Climate Change outlining their individual commitments to cutting greenhouse gas emissions by 2025 or 2030.  The new study finds that, even if all the countries follow through on their commitments, steeper cuts would be necessary after 2030 to stay below 2 degrees of warming. And by the end of the century, total emissions would need to become negative, meaning more greenhouse gases would be removed from the air than are emitted into the atmosphere. These negative emissions would need to reach net minus 15 gigatons of "carbon dioxide equivalent," a measure that tabulates the global warming potential of all types of greenhouse gases in relation to carbon dioxide, according to model simulations created for the study. Worldwide, yearly greenhouse gas emissions now equal about 50 gigatons of carbon dioxide equivalent. "The emissions targets in the Paris Agreement are an important first step, and it's known that additional action will be required to meet the goal of limiting warming to 2 degrees," said NCAR scientist Benjamin Sanderson, lead author of the study. "This paper provides details of what the next steps would need to look like in order to actually hit that target." The study, published in Geophysical Research Letters, a journal of the American Geophysical Union, was funded by the U.S. Department of Energy and by the National Science Foundation, NCAR's sponsor.   This graph represents eight possible pathways that society could take to have a two-in-three chance of limiting warming to 2 degrees Celsius.  The blue line represents our current emissions trajectory. The red line represents the path that society will be on if countries adhere to the Paris Agreement. The gray lines represent other possibilities, all of which require more stringent emissions cuts in the near term but fewer negative emissions later. Click to enlarge. (©UCAR. This image is freely available for media & nonprofit use.) Small changes now equal big benefits later Even before the Paris agreement was finished, it was clear that the pledged emissions cuts by 2030 would not be sufficient on their own to meet the target of limiting warming to 2 degrees. This study gives a comprehensive look at the possible paths society could take to have a two-in-three chance of staying below the target. "We created a wide range of possible global emissions pathways that would allow us to have a decent shot at limiting warming to two degrees," said Sanderson. "We found that very small increases in the rate at which we cut greenhouse gases now could lead to very large decreases in the amount of negative emissions we need later."  Negative emissions in the future will require the massive deployment of technologies that are still hypothetical to draw down greenhouse gases from the atmosphere. That makes it difficult to know how capable society will be to implement large-scale carbon removal in the future. Sanderson and his colleagues, NCAR scientists Brian O'Neill and Claudia Tebaldi, also found that it is still possible to stay below 2 degrees of warming without net negative emissions, but to do so would require near-term cuts that are much more aggressive than those proposed in the Paris agreement. About the article Benjamin M. Sanderson, Brian C. O’Neill, and Claudia Tebaldi, What would it take to achieve the Paris temperature targets?, Geophysical Research Letters Writer/contact:Laura Snider, Senior Science Writer

Sizing up cyclones

May 18, 2016 | In early July 2005, Hurricane Dennis, a Category 3 storm on the Saffir-Simpson Hurricane Wind Scale, was bearing down on the Gulf Coast. Anyone paying attention would have been forgiven for having a foreboding sense of déjà vu.  Just 10 months earlier, another Category 3 storm, Hurricane Ivan, had followed a strikingly similar track, making landfall just west of Gulf Shores, Alabama. Ivan ravaged the region, ultimately causing an estimated $18.8 billion in damages. But Dennis, despite roaring ashore in practically the same neighborhood, caused only $2.5 billion in damages—less than one-seventh that caused by Ivan. The fact that two Category 3 hurricanes making similar landfall less than one year apart had such different impacts illustrates a weakness in the Saffir-Simpson scale, the system most commonly used by weather forecasters to categorize hurricane risk. Scientists at the National Center for Atmospheric Research (NCAR)—in collaboration with global insurance broker Willis—have developed a new index that they suspect can do a better job of quantifying a hurricane's ability to cause destruction. The Cyclone Damage Potential index (CDP) rates storms on a scale of 1 to 10, with 10 being the greatest potential for destruction. A prototype for an app that will allow risk managers to easily use the CDP to identify local damage potential is already available and will be among the first tools included in the beta version of the NCAR-based Global Risk, Resilience, and Impacts Toolbox when it is released later this year. Infrared satellite imagery of Hurricane Ivan (left) and Hurricane Dennis (right). Both storms were rated Category 3, both made landfall in almost the same area, and yet they caused vastly different amounts of damage. Click to enlarge. (Images courtesy NOAA.) Moving beyond wind speed On the frequently used Saffir-Simpson Hurricane Wind Scale, hurricanes are placed in one of five categories, based on their sustained wind speeds. On the low end, Category 1 storms have sustained winds between 74–95 mph and are expected to cause "some damage." On the high end, Category 5 storms have sustained winds of 157 mph or higher and are expected to cause "catastrophic damage." Because the Saffir-Simpson scale relies solely on sustained wind speeds, it does not take into account all the characteristics of a storm linked to its destructive power. "Hurricane wind damage is driven by more than simply wind speed," said James Done, one of three NCAR scientists who worked on the CDP. "The hurricane's size and forward speed also are important. A large, slowly moving hurricane that repeatedly batters an area with high winds can cause greater total damage than a smaller, faster hurricane that blows quickly through a region." Damage caused to a marina in New Orleans by Hurricane Katrina. Katrina would have received a CDP rating of 6.6, compared to a 5.0 for Hurricane Ivan and a 2.4 for Hurricane Dennis. (Image courtesy NOAA. Click here for high resolution.) For example, the critical difference between Ivan and Dennis turned out to be hurricane size, according to a study of the storms by Done and Jeffrey Czajkowski at the University of Pennsylvania's Wharton Risk Management and Decision Processes Center. To create the CDP, the scientists incorporated hurricane size and forward speed into their index, along with sustained winds. To determine the relative importance of each, the team used hurricane damage statistics from the hundreds of offshore oil and gas facilities that pepper the northern Gulf of Mexico. Because facilities are spread more-or-less evenly across the region, their exposure to hurricanes is approximately the same. Damage differences from storm to storm can therefore be attributed to differences in the storms themselves.  The CDP does not predict actual damage – which could vary markedly, depending on where (or if) a hurricane makes landfall – but instead predicts the storm's potential. When applying the CDP to past hurricanes, the index was able to discern a difference between Ivan, which would have scored 5.0 on the CDP prior to landfall, and the much smaller Dennis, which would have earned a 2.4. The CDP rating for Hurricane Katrina, which ultimately caused more than $80 billion in damages in 2005, would have been 6.6. “The value of the index is in comparing current storms with storms from the past," Done said. "For example, if a hurricane is approaching New Orleans, you can compare its CDP with Hurricane Katrina's CDP and get a fuller picture of how much damage the storm is likely to cause." The CDP project was led by NCAR scientist Greg Holland, along with NCAR colleagues Done, Ming Ge, and Willis collaborator Rowan Douglas. Dive deeper From today's storm to tomorrow's climate In its original form, the CDP can be easily applied in real time to existing hurricanes. But Done also wanted to find a way to examine how hurricane damage might change in the future, especially as the climate warms.  The question of how climate change may influence hurricanes has been difficult to answer, in part because global climate models are typically not able to "see" the small-scale details of individual storms. Though some scientists have run climate models at a resolution that is fine enough to study hurricane formation, the effort requires so much computing power that it hasn't been practical to replicate on a large scale. To skirt this problem, hurricane researchers have looked for links between hurricane activity and phenomena that climate models can see—for example, the sea surface temperatures of ocean basins. "People have used large-scale variables to infer tropical cyclone activity for decades," Done said. "I've done a similar thing, but instead of predicting how many hurricanes will form, I’m predicting hurricane damage potential." To make this "climate" version of the CDP, Done – together with NCAR colleagues Debasish PaiMazumder and Erin Towler, and Indian Space Research Organization collaborator Chandra Kishtawal – looked for variables in the large-scale environment that could be correlated to the three variables used for the original CDP: sustained winds, size, and storm speed. The team found that "steering flow," the winds that would blow along a hurricane, is correlated with forward speed. They also found that relative sea surface temperature – the difference between temperatures in the Atlantic and Pacific ocean basins – is linked to seasonal average hurricane intensity and size. This is because relative sea surface temperatures affect wind speeds higher up in the atmosphere, which in turn affect hurricane formation.  The result is an index that can spit out a damage potential rating for a season, a year, or even longer, without needing to predict how many individual storms might form. Such forecasts are of interest to large reinsurance companies, like Willis Re and others. "This technique enables us to translate our climate model simulations into information about extreme events that’s critical for businesses and policy makers,” Done said. Writer/ContactLaura Snider, Senior Science Writer and Public information Officer FundersResearch Partnership to Secure Energy for AmericaWillis Re  CollaboratorsEngineering for Climate Extremes PartnershipWillis Re

Rising Voices melds indigenous, western science perspectives

March 24, 2016 | Indigenous people around the world are often among the first to experience the consequences of extreme weather and climate change. The effects on their lives and livelihoods of sea level rise, changes in farming and fishing seasons, and other environmental impacts often are dramatic. Yet their perspectives are rarely considered in public policy discussions. In many tribal communities, climate change exacerbates a situation already marked by economic hardship, resource loss, and discrimination. Now in its fourth year, a program hosted by NCAR called Rising Voices brings social and physical scientists and engineers together with Native American community members to build bonds that lead to collaboration on research proposals and projects. The premise is that indigenous peoples experience and understand the changes occurring in their communities, while scientists can provide insight on the underlying causes and how those changes might be managed. "We need to appreciate the experience and knowledge that has been transferred from generation to generation to generation in Native American communities," said Bob Gough, a founding member of Rising Voices, an attorney, and a descendant of the Leni Lenape tribe of Delaware. Rising Voices co-founder Bob Gough (far right), speaks at a Rising Voices workshop in Boulder. An attorney and descendant of the Leni Lenape tribe of Delaware, Gough has been involved in Native American and climate change issues for decades. (Photo by Craig Elevitch.) For NCAR Director Jim Hurrell, indigenous knowledge systems are critical to understanding the current and future impacts of climate variability and change, and "they are especially central to discussions around adaptation strategies. Rising Voices has been tremendously successful in bringing the indigenous and scientific communities together on these issues, and the collaborative efforts that are emerging are going to pay tremendous dividends." Many of the indigenous communities involved in Rising Voices are already contending with significant impacts. In January, the U.S. Department of Housing and Urban Development announced it would fund a proposal to resettle the Isle de Jean Charles Band of the Biloxi-Chitimacha-Choctaw tribe, a Louisiana Bayou community that has lost virtually all its land due to rising sea levels and to erosion caused by extreme weather as well as human activities such as oil and gas development. This is believed to be the first resettlement in the United States related to climate change. Rising Voices co-founder and NCAR scientist Heather Lazrus. (Photo by Kat Barr.) A Native American village in Kivalina, Alaska, is expected to soon face a similar fate, while many tribes in the Southwest are struggling with severe drought and scarce water. Members of both the Isle de Jean Charles and Kivalina tribes participate in Rising Voices. Bull Bennett, an ecologist, Mi'kmaq tribal member in North Dakota, and Rising Voices participant gave a vivid example of just one problem facing cold-climate communities during a video interview last summer for a new climate exhibit at NCAR's Mesa Lab. "Imagine you carve out your cellar in the permafrost and that's how you store your meat in the lean times," Bennett said. "And now imagine the permafrost thaws and your basement is full of water and the structure isn't supported and it falls in. That's what communities in Alaska are dealing with in the interior, with profound permafrost thaw. And it's only going to get worse." UN panel urges scientists to tap indigenous knowledge Rising Voices comes at a time of increasing recognition of the role indigenous people play worldwide in climate issues. In 2014, the United Nation's Intergovernmental Panel on Climate Change highlighted how indigenous knowledge and practice, including the "holistic view of community and environment, are a major resource for adapting to climate change." Building bonds, respecting cultural protocols Eileen Shea, former director of climate services at the National Oceanic and Atmospheric Administration and a participant in Rising Voices since the beginning, said establishing common ground through cultural ceremonies is a critical element of building trust between indigenous people and scientists. She still remembers a NOAA workshop she helped coordinate in Hawaii in 1998 that opened with a hula chant and dance. Far from being a tourist gimmick, the chants, when translated into English, described how the winds would periodically change direction and bring warmer water near the shoreline, negatively affecting fishing. "You could hear scientists in the back say, That must have been an El Niño," Shea recalled. When another chant talked about changes over a longer period that affected plants, water resources, and fish, "you could hear scientists in the back say, They are talking about the PDO.” The Pacific Decadal Oscillation is a recurring pattern of ocean-atmosphere climate variability over the mid-latitudes of the Pacific Ocean. Such protocols help to build mutual respect and trust, Shea said. "It puts everyone on a level playing field." In the case of Rising Voices, "over the years people have felt more comfortable sharing their stories of the weather and storms and ice breaks," Shea said. And, as indigenous people recount how their seasonal weather, along with their hunting and fishing calendars, have changed over the years, "you begin to see some alignment with Western science and history." The Rising Voices program grew out of a hallway coffee conversation three years ago between Gough and Heather Lazrus, an NCAR environmental anthropologist. At the time, Gough was involved in a project to improve wind-energy predictions and map Indian reservations for potential renewable energy projects. Initially intended as a one-time workshop, Rising Voices received additional funding for subsequent workshops which have been organized by Lazrus, Gough, and Julie Maldonado of the Livelihoods Knowledge Exchange Network. The NCAR Director's Office is the primary funder. Rising Voices has grown from 45 participants at the first workshop to more than 110 at the third annual workshop last July. (NCAR hosted a similar meeting in 2008). Gough, who grew up clamming and fishing on former tribal homelands on the New Jersey Coast, has been involved in tribal climate and energy issues for several decades. He said that while there are academic efforts to include indigenous people, Rising Voices fills a niche as a community-oriented group that connects tribes to each other and to scientists. Participants have also come from the U.S. National Climate Assessment and the Department of Interior's Climate Science Centers. In a survey of last summer's workshop participants, nearly two-thirds of respondents said they came away with a stronger appreciation of cultural protocols and knowledge required for partnerships in key areas, including water, relocation, climate cycles, and health and livelihood hazards. More than three-quarters said the workshop supported collaborative scientific-indigenous partnerships "extremely well" or "a lot." Lazrus said the ultimate goal is for indigenous perspectives to inform science. For example, Rising Voices is a formal partner in NCAR's Engineering for Climate Extremes Partnership, which is developing tools that help communities adapt and build resilience to extreme weather events. But while outcomes are important, the primary benefits of Rising Voices right now are to encourage connections and collaboration, and to support indigenous science students and early-career scientists. "In those respects," Lazrus said, "Rising Voices is succeeding."   Writer/contactJeff Smith, Science Writer and Public Information Officer FundersNCAR DirectorateNorth Central Climate Science Center Colorado State University CollaboratorsIntertribal Council on Utility Policy Kiksapa Consulting LLCIndigenous People's Climate Change Working Group

Global food system faces multiple threats from climate change

BOULDER — Climate change is likely to have far-reaching impacts on food security throughout the world, especially for the poor and those living in tropical regions, according to a new international report that includes three co-authors from the National Center for Atmospheric Research (NCAR). The report, issued today at the Paris 2015 United Nations Climate Conference (also known as COP21) warns that warmer temperatures and altered precipitation patterns can threaten food production, disrupt transportation systems, and degrade food safety, among other impacts. As a result, international progress in the past few decades toward improving food security will be difficult to maintain. The report, Climate Change, Global Food Security, and the U.S. Food System, provides an overview of recent research in climate change and agriculture. Led by the U.S. Department of Agriculture and published under the auspices of the U.S. Global Change Research Program, it includes contributors from 19 federal, academic, nongovernmental, intergovernmental, and private organizations in the United States, Argentina, Britain, and Thailand. “If society continues on a path of high emissions of greenhouse gases, there is no way around the fact that climate change is going to be a primary challenge for producing and distributing food,” said NCAR scientist Claudia Tebaldi, a co-author of the report. “If society lowers emissions, climate change will still be a stressor on food security, but other factors such as socioeconomic conditions could be more critical.” Two other NCAR scientists—Caspar Ammann and Brian O’Neill—also served as co-authors. The report was produced as part of a collaboration between NCAR, the Department of Agriculture, and the University Corporation for Atmospheric Research, which manages NCAR on behalf of the National Science Foundation. A farmer tills his field. (Photo by Keith Weller, U.S. Department of Agriculture.) The report focuses 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. “Changes in society and changes in climate will both be critically important to food security in the coming decades,” O’Neill said. “This means we have to do a better job of anticipating possible changes in income, governance, inequality, and other factors, and a better job understanding how they interact with food security and climate change.” Among the report’s key findings: The impact of climate change on crop and livestock productivity is projected to be larger for tropical and subtropical regions such as Africa and South Asia, although there will be regional variations. Wealthy populations and temperate regions are less at risk, and some high-latitude regions may temporarily experience productivity increases, in part because of warmer temperatures and more precipitation. However, if society continues to emit more carbon dioxide and other greenhouse gases that cause climate change, even those regions will face damaging outcomes during the second half of this century. Climate change has important implications for food producers and consumers in the United States. The nation is likely to experience changes in the types and cost of food available for import. It can also expect to face increased demand for agricultural exports from regions coping with production difficulties. Climate change risks extend beyond agricultural production to critical elements of global food systems, including processing, storage, transportation, and consumption. For example, warmer temperatures can have a negative impact on food storage and increase food safety risks; higher sea levels and changes to lake and river levels can impede transportation. Risks to food security will increase with a higher magnitude and faster rate of climate change. In a worst-case scenario based on high greenhouse gas concentrations, high population growth, and low economic growth, the number of people at risk of undernourishment would increase by as much as 175 million by 2080 over today’s level of about 805 million. This would reverse recent gains, as the number of people at risk of undernourishment has dropped from about 1 billion since the early 1990s. Society can take steps to reduce the food system’s vulnerability to climate change, ranging from more advanced growing methods to cold storage, improvements in transportation infrastructure, and other strategies. Such adaptations, however, may be difficult to implement in some regions due to availability of water, soil nutrients, infrastructure, funding, or other factors. More information: Climate Change, Global Food Security, and the U.S. Food SystemUSDA and UCAR videos about the new report

Saving farmers money in tropical West Africa

November 18, 2015 | Ashai Abdul is one of thousands of farmers in the West African country of Ghana who receive text messages with custom rain forecasts based on an advanced weather model developed at NCAR. The subscription-based service has already paid off. One day, on seeing that heavy rain was forecast, Abdul delayed plans to bring in machinery and extra workers to his corn, rice, and soybean farm in northern Ghana. "I had the money still to hire the equipment another day and not lose my investment," he later told the forecast provider. The forecasts are produced by Swedish-based Ignitia, which adapted the Weather Research and Forecasting Model (WRF) to a tropical climate. NCAR has been a lead developer of WRF and supports training and use of the open-source code by a large worldwide user community. Farmers in northern Ghana check the latest weather forecast via text message on their cell phone. (Photo courtesy Ignitia. Photo by Ike Nortey Focus Xtreme Photography, Accra, Ghana.) Accurate weather forecasts have huge potential across Africa, where crops are largely rain-fed. The forecasts in Ghana help farmers with key decisions, such as knowing when to plant, when to spray, and when to bring in extra labor and machinery. "We're excited to see an innovative use of WRF that's helping agriculture in West Africa," said NCAR scientist Jordan Powers, who manages efforts involving WRF at NCAR. Adapting to the tropics Adapting the model to West Africa presented a challenge, since WRF was initially developed to simulate weather in the temperate latitudes of North America and Europe.  "The weather in West Africa is so different – no low pressure, no high pressure, no fronts driving everyday weather," said Ignitia chief executive Liisa Petrykowska, who has expertise in meteorology and physics. "Most local weather in the tropics is notoriously hard to model." Moisture and heat are the primary drivers creating unstable weather conditions in the tropics. Large-scale pressure fields aren’t much of a factor, except in large tropical cyclones. While tropical weather is more regular overall, more microscale processes are at work, making it difficult for forecasters to predict rain accurately in a particular area. Thunderstorms, for example, can emerge, evolve, and fade quickly. Farmer Ashai Abdul and his son meet with Ignitia Chief Executive Liisa Petrykowska in northern Ghana to discuss their use of Ignitia's rainfall forecast and its benefits for their rice crop. (Photo courtesy Ignitia. Photo by Ike Nortey Focus Xtreme Photography, Accra, Ghana.) After years of trying and almost giving up, Ignitia scientists came up with a high-resolution version of WRF with data points two- to five-miles (3 km to 9 km) apart. They in effect developed a hybrid system that combines WRF with their own model. The new system, trademarked as iska, especially focuses on solar heating at and near the surface of the Earth, and on the physical processes of cloud formation, cloud growth, and precipitation. According to Ignitia, its short-range rain forecasts are 84 percent accurate. Petrykowska said she and other Ignitia scientists had worked with WRF before. "It wasn’t a new platform for us. The point though was making it efficient as a forecasting tool for the tropics." Empowerment via cell phone Iska was tested in 2013, then offered as a subscription service to farmers in 2014. Since most Ghanaians have basic cell phones, Ignitia partners with a cell service provider to get approximate GPS coordinates of the farms. Petrykowska said the company now has more than 80,000 subscriptions, the large majority of which are paid by farmers themselves. The company did text-message trials using local languages and symbols, but concluded that communicating in English was the best way to go. Local languages are spoken more than written and some symbols were confusing, Petrykowska said. The text messages have a simple, standard structure, such as: "Today dry, tomorrow heavy rain." Although many farmers are illiterate, they quickly learn what the words mean, or ask their village chief to translate, Petrykowska said. Subscribers get a daily 48-hour forecast, a monthly outlook, and a six-month seasonal outlook. Their phone is debited 3-4 cents per text message. Surveys have shown that corn farmers who subscribe to the service have experienced up to an 80 percent jump in income, while cocoa farmers report a 40 to 50 percent boost. Ghana is the world’s second largest producer of cocoa beans, the key ingredient in chocolate. But Ghana’s cocoa bean production declined dramatically in the 2014-15 season because of lack of rainfall and a short supply of pesticides to combat a fungus that can destroy cocoa pods. "We’ve heard a lot of stories where our forecasts have helped those farmers who subscribe to better know when to spray their trees with fungicide," Petrykowska said.  "If they spray and then it rains, then the chemicals run off and they can’t afford to buy more pesticide, and yields decrease." Ignitia is structured as a for-profit business, but has received support for its development and start-up operations from the Swedish International Development Cooperation, USAID and others. Petrykowska said the break-even point is about 100,000 subscribers. The company has agreements with cell service providers to expand operations in West Africa to the Ivory Coast, Mali, Niger, Nigeria and Senegal. Writer/contactJeff Smith, Science Writer and Public Information Officer            

What's driving soot across India?

October 12, 2015 | As a teenager in the 1990s, NCAR postdoctoral scientist Rajesh Kumar bicycled five miles from his village north of Delhi to school. He remembers riding through clear skies and fog, but not smog. Today, Delhi ranks as the most polluted city in the world with 12 additional Indian cities in the notorious top 20, according to the urban air database released last year by the World Health Organization. In Delhi alone, small particulates averaged six times the recommended maximum, a hazard to the health especially of children and the elderly. Smog also contributes to climate change by trapping heat that otherwise would escape the atmosphere. Scientists have identified the sources and transport patterns of black carbon soot, a health and visibility problem for a dozen Indian cities, including Delhi, shown here enveloped in smog. (Photo by Jean-Etienne Minh-Duy Poirrier, Creative Commons [CC BY-SA 2.0], via Flickr.) Experiencing increased air pollution in his home country has inspired Kumar to understand more about its driving forces and remedies. Most recently, the researcher was lead author on a paper concluding that black carbon emissions—fine particles or soot caused by the incomplete burning of fossil fuels and biomass from plant or animal waste—are transported in the atmosphere across India. Only 5 percent of the emissions at any given time blow in from outside the country.   Black carbon emissions from northern India, for example, contribute up to 30 percent to black carbon pollution in southern India during the winter, the study found, while southern India makes a similar contribution to northern India during the summer monsoon season. While human activity—agricultural waste burning, use of household cook stoves, industry and vehicles—is the cause of most black carbon emissions, the seasonal cycle is driven by the monsoon weather. "What this means is that India has the power to reduce black carbon emissions significantly—but only if individual states and regions work together on mitigation strategies," said Kumar. The paper appears in the Journal of Geophysical Research – Atmospheres. A research team headed by Kumar now is conducting a simulation of how air quality is likely to change in South Asia overall by mid-century, a topic he will discuss at the American Geophysical Union’s fall meeting in December. Haze from urban and industrial pollution, as well as agricultural and wildland fires (red dots), can be seen over northern India below the Himalayan mountain range in this satellite image from October 2014. (Photo courtesy NASA.) Shining a spotlight on soot Co-author Mary Barth, an NCAR scientist, noted that attention to black carbon emissions has grown as more is known about its ability to strongly absorb solar radiation. The issue is especially of concern in densely populated areas such as the Indo-Gangetic Plain, which consists of Bangladesh and swaths of India and Pakistan. There is concern not only due to black carbon's atmospheric impacts, but also because soot that settles on snow absorbs more heat from the Sun and thus accelerates melting. Emission levels are so high in that region that there is concern about glacier melt in the Himalayas—the region's primary storehouse of water. "If you curtail black carbon emissions, you can reduce heat over the short term," Barth said. "It's something you can do while working to reduce carbon dioxide levels in the atmosphere." Black carbon has a short life span of only a week or two, while carbon dioxide molecules remain in the atmosphere for about 100 years. Prior studies have provided important information about black carbon pollution in parts of India, but they didn't detail the specifics of how the particles are transported across the country. For their observational database, the research team used monthly average black carbon concentrations reported from 21 sites representing a range of environments, including cities, semi-urban areas, and coastal areas. They also took meteorological data into account. The team then developed models for tracking air pollutants that were combined with the NCAR-based Weather Research and Forecasting Model. NCAR researcher Rajesh Kumar studies black carbon emission levels. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use. While the computer model reproduced the seasonal cycle of black carbon emissions fairly well, it was more difficult to capture that seasonality in the complex terrain of the Himalayan region. Kumar, who also has studied the impact of ozone pollution on India's agriculture production, notes that India is taking steps to improve its air quality. Efforts include national programs to promote liquefied petroleum gas for cooking and solar power for energy production and irrigation. "I hope that in 20 years or so, India will be able to talk about its good air quality, not its pollution," Kumar said.  About the article Rajesh Kumar, M. C. Barth, G. G. Pfister, V. S. Nair, Sachin D. Ghude, and N. Ojha, 2015: What controls the seasonal cycle of black carbon aerosols in India? Journal of Geophysical Research - Atmospheres, 120, 7788-7812, DOI: 10.1002/2015JD023298 | OpenSky Dive Deeper Variability in emission levels was simulated by applying a tagging technique developed by Kumar. The technique consists of assigning 10 different values or "tracers" to standard black carbon particles in order to track the emissions from different regions and sources. For example, separate tracers were assigned to emissions from four regions of India and from outside the country to determine geographic variability. Traditionally, researchers would have done a separate simulation for each tracer, or variable. Putting all 10 tracers in the model at the same time saved a tremendous amount of computing time, Kumar said. The data, crunched by the NCAR-Wyoming Supercomputing Center's Yellowstone system, took only about a tenth the time of the traditional method. Writer/contact Jeff Smith, Science Writer and Public Information Officer Collaborating organizations Indian Institute of Tropical Meteorology Max Planck Institute for Chemistry, Germany Vikram Sarabhai Space Center, India. Funder National Science Foundation

Picturing the forecast: National Weather Service graphics developed with NCAR research

BOULDER – New online graphics being rolled out this summer by the National Weather Service (NWS) are based on research by a team of risk communication experts at the National Center for Atmospheric Research (NCAR) who focused on how to better convey forecast information visually. Beginning July 7 the NWS will use the redesigned icons for all weather.gov local forecasts. These point-and-click forecasts influence weather-related decisions by people across the country, drawing 2 to 4 million unique web views daily. The new icons will feature split images and color-coded boxes to better communicate the existence, timing, and potential severity of upcoming weather threats. For example, instead of portraying a night as entirely rainy, a split image could show a 30 percent chance of rain in the early part of the evening, followed by partial clearing after midnight. Colored rectangles drawn around the images will also be used to call attention to weather threats, with yellow denoting a watch, orange denoting an advisory, and red denoting a warning. Existing NWS forecast graphics (top) emphasize the probability of rain and other weather events. The redesigned graphics (bottom) contain more information about the timing and potential severity of forecast weather systems. These examples are from the June 26 forecast for Bridgeport, Ohio. To view local forecasts for other areas, visit weather.gov. The changes are based on several years of work by a multidisciplinary team at NCAR that worked closely with the NWS, an agency within the National Oceanic and Atmospheric Administration. The team developed prototype graphics and surveyed tens of thousands of weather.gov local forecast users, finding that specific improvements to the graphics could greatly improve public understanding of the forecasts. “We want to help people better understand when there’s a major weather threat and when it’s likely to occur,” said NCAR’s Julie Demuth, a researcher who specializes in communicating weather risks to the public. “The main goal is to better convey information that's critical for protecting lives and protecting property.” Eli Jacks, acting chief of the NWS’s Forecast Services Division, said the changes are an important step toward helping people make better use of NWS forecasts. “Just putting out the forecast is no longer enough,” he said. “This helps users interpret the forecast more easily and use it to make informed decisions.” NWS director Louis Uccellini said the new project demonstrates the importance of research in communicating forecasts to the public. “Research provides the essential backbone to any effective operational product used by the National Weather Service to protect lives and property,” Uccellini said. “Not only must we have advancements in atmospheric science to improve forecasts and services, we must also infuse social science to ensure we are communicating forecast information in a way that is clear and understandable so people can take appropriate action.” The work was primarily funded by the NWS, with additional support from NOAA and the National Science Foundation, which sponsors NCAR. Forecasts at a glance Demuth and her colleagues began looking into the issue several years ago when the NWS wanted to determine if the icons could communicate weather information more clearly. An icon depicting rain, for example, might prompt people to cancel outdoor plans even if there was just a 10 percent chance of showers for a few hours. The research team, working with the NWS, focused on better transmitting two aspects of a forecast that are crucial for helping people understand their risk: the existence of a hazardous weather threat and the timing of that threat. They developed experimental graphics and text with the goal of conveying sometimes complex information in a way that is easy to interpret. “This is supposed to be a forecast at a glance, so we adapted the approach using NCAR’s work as a basis.” Jacks said. “Ideally a user will look at it and get a pretty good idea of what is expected.” Demuth and her colleagues conducted two rounds of surveys with more than 13,000 users of NWS forecasts, asking them to evaluate designs to see which one was best at communicating a severe thunderstorm warning and a flood watch. The surveys showed that users were significantly better at identifying the timing and nature of the weather threat when the information was presented with new graphics and reinforced with wording that stated the start and stop times of the threat. For example, more than 97 percent of survey respondents correctly identified the start and end time of the flood watch with the revamped graphics and text, compared to less than 4 percent in a control group using the existing NWS presentation. The research team summarized its findings in a 2013 paper in Weather and Forecasting, an American Meteorological Society journal. Building on this work, the NWS further refined the icons and began to test them last year, asking for input from thousands of users. The agency is now previewing the new graphical approach on its website as it prepares to launch the new version across the nation next month. “This work illustrates the importance of evaluating how people interpret information about risks, particularly when it’s a matter of public safety,” Demuth said. “Making improvements in how we communicate hazardous weather information—even seemingly small improvements—can translate into very large benefits for society.” “It’s gratifying to be part of a collaboration where NCAR research is being used to help the National Weather Service alert people across the U.S. about potentially dangerous weather," said Thomas Bogdan, president of the University Corporation for Atmospheric Research, which manages NCAR. "This is a great example of how investments in science lead to substantial benefits for society.”

Exposure of U.S. population to extreme heat could quadruple by mid-century

BOULDER – U.S. residents' exposure to extreme heat could increase four- to six-fold by mid-century, due to both a warming climate and a population that's growing especially fast in the hottest regions of the country, according to new research.  The study, by researchers at the National Center for Atmospheric Research (NCAR) and the City University of New York (CUNY), highlights the importance of considering societal changes when trying to determine future climate impacts. "Both population change and climate change matter," said NCAR scientist Brian O'Neill, one of the study’s co-authors. "If you want to know how heat waves will affect health in the future, you have to consider both." Extreme heat kills more people in the United States than any other weather-related event, and scientists generally expect the number of deadly heat waves to increase as the climate warms. The new study, published May 18 in the journal Nature Climate Change, finds that the overall exposure of Americans to these future heat waves would be vastly underestimated if the role of population changes were ignored. The total number of people exposed to extreme heat is expected to increase the most in cities across the country's southern reaches, including Atlanta, Charlotte, Dallas, Houston, Oklahoma City, Phoenix, Tampa, and San Antonio. The research was funded by the National Science Foundation, which is NCAR's sponsor, and the U.S. Department of Energy.  Climate, population, and how they interact For the study, the research team used 11 different high-resolution simulations of future temperatures across the United States between 2041 and 2070, assuming no major reductions in greenhouse gas emissions. The simulations were produced with a suite of global and regional climate models as part of the North American Regional Climate Change Assessment Program.  Using a newly developed demographic model, the scientists also studied how the U.S. population is expected to grow and shift regionally during the same time period, assuming current migration trends within the country continue. Total exposure to extreme heat was calculated in "person-days" by multiplying the number of days when the temperature is expected to hit at least 95 degrees by the number of people who are projected to live in the areas where extreme heat is occurring. The results are that the average annual exposure to extreme heat in the United States during the study period is expected to be between 10 and 14 billion person-days, compared to an annual average of 2.3 billion person-days between 1971 and 2000. This graphic illustrates the expected increase in average annual person-days of exposure to extreme heat for each U.S. Census Division when comparing the period 1971–2000 to the period 2041–2070. Person-days are calculated by multiplying the number of days when the temperature is expected to hit at least 95 degrees by the number of people who are projected to live in the areas where extreme heat is occurring. The scale is in billions. (©UCAR. This image is freely available for media & nonprofit use.) Of that increase, roughly a third is due solely to the warming climate (the increase in exposure to extreme heat that would be expected even if the population remained unchanged). Another third is due solely to population change (the increase in exposure that would be expected if climate remained unchanged but the population continued to grow and people continued to moved to warmer places). The final third is due to the interaction between the two (the increase in exposure expected because the population is growing fastest in places that are also getting hotter). "We asked, 'Where are the people moving? Where are the climate hot spots? How do those two things interact?'" said NCAR scientist Linda Mearns, also a study co-author. "When we looked at the country as a whole, we found that each factor had relatively equal effect." At a regional scale, the picture is different. In some areas of the country, climate change packs a bigger punch than population growth and vice versa. For example, in the U.S. Mountain region—defined by the Census Bureau as the area stretching from Montana and Idaho south to Arizona and New Mexico—the impact of a growing population significantly outstrips the impact of a warming climate. But the opposite is true in the South Atlantic region, which encompasses the area from West Virginia and Maryland south through Florida. Exposure vs. vulnerability Regardless of the relative role that population or climate plays, some increase in total exposure to extreme heat is expected in every region of the continental United States. Even so, the study authors caution that exposure is not necessarily the same thing as vulnerability. "Our study does not say how vulnerable or not people might be in the future," O'Neill said. "We show that heat exposure will go up, but we don't know how many of the people exposed will or won't have air conditioners or easy access to public health centers, for example." The authors also hope the study will inspire other researchers to more frequently incorporate social factors, such as population change, into studies of climate change impacts. "There has been so much written regarding the potential impacts of climate change, particularly as they relate to physical climate extremes," said Bryan Jones, a postdoctoral researcher at the CUNY Institute for Demographic Research and lead author of the study. "However, it is how people experience these extremes that will ultimately shape the broader public perception of climate change." About the article Title: "Future population exposure to U.S. heat extremes"Authors: Bryan Jones, Brian C. O’Neill, Larry McDaniel, Seth McGinnis, Linda O. Mearns, and Claudia TebaldiPublication: Nature Climate Change  

A hurricane by any name

June 11, 2014 | According to the results of a high-profile study last week, people may take a hurricane named Glen a bit more seriously than one named Glenda. But the perceived gender of a hurricane’s name is just one of many factors potentially shaping how someone reacts to a given storm, according to several scientists at NCAR who take a multifaceted approach to studying hurricane response. While hurricane forecasts have improved substantially over the years, NCAR experts stress that the forecast and warning information on a given storm must be communicated as clearly and quickly as possible in order to save lives in coastal and inland communities. This is an increasingly complex undertaking as Facebook, Twitter, and other outlets are transforming the ways that people get information. “People get a variety of information over time about the risks they face as a hurricane approaches. We need to understand how that information evolves, and how that influences people’s risk perceptions and responses,” said Julie Demuth, an NCAR researcher who studies societal aspects of hazardous weather. As Hurricane Sandy approached on October 27, 2012, emergency officials in Old Saybrook, Connecticut, combined highway signs with a dedicated website to notify the public of mandatory evacuation plans. (Screen capture from video by Robert Rose/FEMA.) Demuth and her colleagues Rebecca Morss and Jeff Lazo found themselves peppered with media inquiries after a study titled "Female hurricanes are deadlier than male hurricanes" appeared in the Proceedings of the National Academy of Sciences. The study concluded that landfalling U.S. hurricanes with feminine names took more lives in recent decades than those with masculine names. The study also included experiments to find out how subjects respond to hurricane names and their perceived gender. Critics have lobbed a volley of counterarguments at the PNAS paper. The expertise of NCAR group members allowed them to put the study in context, as they’ve spent years looking closely at a number of variables influencing how people respond to hurricane threats. Along with colleague Betty Morrow (SocResearch), the group published a comprehensive analysis last fall in the Bulletin of the American Meteorological Society examining how hurricane risk information is created and communicated. In another study, examining the response to Hurricane Ike in 2008, Morss and colleague Mary Hayden found that a National Weather Service statement warning that Ike’s storm surge in some areas would lead to “certain death” produced counterintuitive responses among some residents. “A lot of factors influence decisions during actual hurricanes,” said Lazo, who thinks any effect from the perceived gender of a hurricane’s name is likely dwarfed in this mix. “How someone responds is affected by demographics, culture, and prior experience, as well as the quality and sources of information they receive, the time of day of landfall, and other variables.” Morss notes that the experimental subjects in the PNAS study weren't in circumstances similar to those faced by coastal residents when a hurricane threatens. “In a real hurricane situation, people are receiving many different pieces of information over a period of hours or days. It can be a very high-pressure situation, where you’re dealing with family interactions, monetary issues, and other constraints,” said Morss. Such real-world complications are all the more reason why in-depth research is needed, she added. “Hurricane Sandy and other recent events have clearly illustrated that there are major gaps in weather risk communication that contribute to loss of life and significant harm,” Morss said. “This is a very important area for further work.” Demuth voiced concerns about several of the methods and conclusions in the PNAS paper, but she told the Washington Post that she hopes the study leads to continuing dialogue and research on the very real question of what factors most influence people’s response to hurricane threats. “Research in risk perception and risk communication is a vital complement to research on how hurricanes behave and how they're predicted. We need all of these in order to protect lives and reduce harm.” Writer/contactBob Henson, NCAR & UCAR Communications ResearchersJulie Demuth, NCARMary Hayden, NCARJeff Lazo, NCARRebecca Morss, NCARBetty Morrow, SocResearch Funders National Science Foundation National Oceanic and Atmospheric Administration Soldiers from the Florida Army National Guard's 3rd Battalion, 20th Special Forces Group, talk to a resident swimming in the flooded section of the White Street Fishing Pier in Key West, Florida, on September 9, 2008. People braved the dangerous conditions at the end of the pier as storm surge from Hurricane Ike crashed over the barriers and flooded the pier. Guardsmen and Key West police officers warned the swimmers of the unsafe conditions, and soon the pier was closed to visitors by city officials. In the background a man holds a child in the dangerous surf. Ike went on to produce catastrophic flooding along the upper Texas coast, resulting in the largest search-and-rescue operation in U.S. history. The hurricane resulted in more than 100 deaths. (Wikimedia Commons photo by Tech. Sgt. Thomas Kielbasa.)

UCAR statement on the White House climate data initiative

BOULDER—The president’s Climate Data Initiative, announced today, will enable new industries to use climate data to enhance long-range decisions and planning. UCAR has long been supportive of data policies that are free, open, and help people create new products to bring value to the lives of Americans. The community climate models we have developed and the wealth of data we provide allow a wide range of companies, foundations, and academics to create their own value-added products for a diverse marketplace that sees value in that data. In the digital age, training approaches like those provided by UCAR's COMET program through open access enable meteorologists, emergency managers, and the public to better understand and use weather and climate data. UCAR supports the president’s climate data initiative because it helps to provide the right data at the right time to make the right decisions.

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