water future package

A splash of reality

August 13, 2012 | When it's clean, plentiful, accessible, and controllable, water is easy to take for granted. Things are different when the supply becomes a torrent—or a trickle. For much of the United States, the summer of 2012 has been one of those times. The most extensive U.S. drought in almost 60 years has enveloped some of the nation’s most productive farmland. The impacts go well beyond agriculture: in parts of the Midwest, shifting soils are cracking building foundations and prompting water restrictions more familiar in California than Indiana. In this image, the large bubble atop the central United States represents the volume of all of Earth's water, including oceans and groundwater. The smaller bubble atop Kentucky denotes the volume of Earth's freshwater (groundwater, lakes, swamp water, and rivers), while the tiny bubble over Georgia represents lakes and rivers alone. (Image courtesy USGS Water Science Photo Gallery.) Even as public attention comes and goes, water is consistently Topic A for a wide-ranging group of researchers. Hydrologists have teamed with meteorologists, climate scientists, and engineers to analyze flood, drought, and water storage. The last decade has seen breakthroughs in the mapping of glaciers and aquifers, plus a steadily improving picture of how water flows into and out of the atmosphere. In the United States, there’s a growing network of drought specialists and an enhanced warning system for regional drought. These advances are running neck and neck with ominous trends. Earth’s warming climate threatens to shunt precipitation toward polar regions and the tropics, with an increased risk of drought at latitudes where billions of people live. Higher temperatures will tend to pull more water out of soils. Even without climatic change, the global demand for water continues to grow hand in hand with population. Water access already varies hugely among countries, and major U.S. aquifers are being depleted at a worrisome pace. As portrayed by the National Drought Mitigation Center, the “hydro-illogical cycle” describes how drought, as a slow-moving natural disaster, tends to emerge under the radar screen, then intensify until people can no longer ignore it or wish it away—until it rains again. (Illustration ©National Drought Mitigation Center.) As they work to understand the hydrologic cycle that sustains our water supply, and the evolution of climate factors that may change it, scientists and policy experts at NCAR and elsewhere bemoan what’s been dubbed the “hydro-illogical cycle,” where pulses of public concern triggered by drought evaporate as soon as the rains return. “We ignore drought until the situation is dire, lament the impacts, justifiably call for help, and clamor for emergency funding,” said J.D. Strong, executive director of the Oklahoma Water Resources Board, in written testimony before Congress on July 25 (see PDF). “But invariably it rains, at which point we forget there was ever a problem and go back to business as usual. We must break this cycle.” In this special report, we take a closer look at water availability and the science that's under way at NCAR, UCAR member universities, and a variety of other partners to help us predict its course. Less water than it seems With more than 70% of Earth covered by oceans, it’s impressive how small the supply of freshwater is by comparison—only about 2 to 3% of the planet’s total water (see graphic). More than two-thirds of that freshwater is locked up in polar ice sheets. Much smaller amounts lie in ice caps and glaciers at lower latitudes, where people can access meltwater. Most of the world’s remaining freshwater is held in deep, inaccessible underground aquifers and within the soil itself. Less than 1% of all global freshwater is readily available in rivers, reservoirs, lakes and shallow aquifers, according to a University of Michigan report. As for the atmosphere, it’s not so much a home for water as a highway for it, according to NCAR's Kevin Trenberth, who heads the scientific steering committee for a major international effort to map the world's energy and water cycles (see sidebar at bottom). According to Trenberth, a typical molecule of water vapor enters the atmosphere from the ocean and spends 8 to 9 days in the air before it returns earthward as rain or snow and flows toward the ocean. At that point, the molecule is usually hundreds or even thousands of miles from the place where it evaporated. Earth’s water is perpetually in motion through the global hydrological cycle, which involves ocean, land, clouds, lakes and rivers, plants, snow, and ice. (© UCAR. UCAR Digital Image Library.) It’s a major task for scientists simply to map out how much water exists at each point in this hydrologic cycle. River flows and reservoir levels are monitored around the world, but many nations are hesitant to release the data for research. Moreover, experts have warned for years that the longstanding network of river gauges in many areas, including the United States, is deteriorating. Measuring evapotranspiration (ET)—the process of water transpiring from plants and evaporating from soil, pavement, and other surfaces into the air—is a challenge of its own. About two-thirds of all rain and snow that falls on land areas ends up entering the atmosphere this way. But there’s not yet a gold-standard measurement technique for ET, and variations in space and time remain poorly mapped. There’s been some promise in combining land-based measurements of ET at specially equipped sites with satellite-based estimates over broader regions. More than a dozen institutions from eight nations have been working over the last several years to evaluate such ET datasets in a project called LandFLux-EVAL. And a team led by NASA’s Matthew Rodell used new ET data to balance the water budgets for seven river basins in Africa, Europe, and North and South America. Evapotranspiration (ET)—the amount of water vapor entering the air from sources other than oceans—varies dramatically across the United States, as shown in this map of total ET for the 2007 growing season (May 1–September 30). In parts of the Deep South, ET averaged as much as 15 mm (0.6 inches) per week. The map was prepared by Baburao Kamble as part of a project to assess ET on a weekly basis using data from NASA’s MODIS satellite. (Image courtesy Baburao Kamble, University of Nebraska Lincoln.) Trenberth and colleagues are using a variety of datasets to put together energy and moisture budgets­ on a continent-by-continent basis, depicting flows in and out of each part of the Earth system over the lifecycle of various ingredients. “We’re trying to see how well we can complete the budget not only for the average but for each month,” says Trenberth, who plans to report on the work in December at the annual meeting of the American Geophysical Union. “I think we may be closer than anyone has been so far.”  Computers and water It’s not only long-term budgets that pose challenges when it comes to modeling the flow of water. For short-term weather models, the emphasis is on correctly depicting the timing and location of rain and snow. This depends on a variety of model aspects, including how observations are assimilated in the model and how well the land surface is depicted, according to NCAR’s Jimy Dudhia. He’s one of the lead developers of ARW, the advanced research version of the multiagency Weather Research and Forecasting model. During 2012 hurricane modeling exercises, researchers used the advanced research version of the Weather Research and Forecasting model (NCAR WRF-ARW) to track Hurricane Ernesto as it weakened and moved inland across southern Mexico. This forecast, issued for 0900 UTC on August 14, projected that more than 204 millimeters (8 inches) of rainfall would fall across some areas (shown in white) over the preceding 111 hours. In this version of the model, the spacing between grid points is 4 kilometers (2.5 miles). Click to enlarge. (Image courtesy NCAR/NESL/MMM.) Dudhia adds that short-term models serve as a critical tool in predicting the risk of flash floods. “This is a challenge because the river flow depends so critically on the position, timing, and intensity of rainfall from thunderstorms, especially over complex terrain,” says Dudhia. Climate models have a different assignment—depicting the trends in water behavior over larger areas and longer periods—so they typically include more aspects of the water cycle, including those that play out gradually. The NCAR-based Community Land Model (CLM), one component of the NSF- and DOE-funded Community Earth System Model (CESM), tracks moisture as it evaporates and transpires, falls as rain or snow, enters river channels, and infiltrates the soil. The CLM also depicts accumulating snowfall and includes a reservoir that simulates the water table. Because of perennial limits on computing power, models like the CLM have often specified glaciers, wetlands, and lakes as elements that remain fixed as the climate evolves. Now, says NCAR land modeler Samuel Levis, “we’re beginning to simulate how some of these water bodies may change in response to simulated changes in the climate.” Another branch of models looks more specifically at where water is headed across and below the land surface, with an eye toward helping water planners. Reed Maxwell (Colorado School of Mines) heads up the ParFlow project, an open-source model of watershed flow that draws on CLM and other components developed at NCAR, Los Alamos National Laboratory, the University of Bonn, and the University of Colorado Boulder. A similar effort in Canada, Hydrogeosphere, was developed at the universities of Laval and Waterloo. At Michigan State University, David Hyndman and colleagues are using integrated hydrologic models to examine how precipitation and temperature may shift as climate change affects the water cycle. (Photo by Kurt Stepnitz, courtesy Michigan State University.) At Michigan State University, a team led by David Hyndman is looking at future changes in the water cycle using MSU’s large-scale, high-resolution Integrated Landscape Hydrology Model. “It’s taking the what-if scenario of projected changes in temperature and precipitation and putting that into something that people understand and relate to,” says Hyndman. Of course, human interventions into the hydrologic cycle can be profound, as people dam rivers, tunnel through mountains, and construct canals to move water from its origins to where it is needed. NCAR scientist David Yates and colleagues at the Stockholm Environment Institute have been developing the Water Evaluation and Planning (WEAP) systems model to help water managers and planners understand the implication of climate on our coupled natural and managed water systems. (See "Who needs glaciers?") Where the moisture is moving As greenhouse gases continue to pile up in a warming atmosphere, the job of tracking and projecting Earth's freshwater gets even more complex. But there’s already a good deal of clarity about the direction of some key water trends. For one thing, higher temperatures are expected to rev up the hydrologic cycle. Warmer air allows more water to evaporate from both land and sea, and that added moisture will tend to intensify rain and snow when and where they form, a trend already being observed in the United States and many other places. On the flip side, the dry spells in between precipitation events will tend to grow longer. Combined with the increased ET from soils, this means an enhanced risk of drought in much of the globe, even where total precipitation may not be changing. New work by NCAR’s Aiguo Dai confirms this outlook.  It’s also become more evident that climate change won’t treat all latitudes equally. Climate models still disagree on how precipitation will change in some regions. However, they concur on the big picture: the dry-leaning zones of the subtropics, centered around latitudes 30°N and 30°S, will tend to expand into the midlatitudes and dry out even further, putting intensified pressure on regional water supplies. For example, the dry, sunny climates found in the southwestern United States and the Middle East have fostered irrigation-dependent agriculture and drawn ever-increasing numbers of residents. Meanwhile, precipitation is expected to increase on average closer to the poles and in the belt of heavy rainfall near the equator that shifts north and south with the seasons. The growth of hydrophilanthropy (Photo courtesy David Kreamer.) Hydrologist David Kreamer (University of Nevada, Las Vegas) is encouraging his peers to look at society’s access to water in the broadest possible terms. At a July 2012 meeting in Boulder, Kreamer pointed out that roughly a billion people lack access to clean drinking water and about 5 million die each year from water-related illnesses. To address these issues, Kreamer and other water experts, including Michael Campana (Oregon State University) and his WaterWired blog, are putting energy toward what Kreamer has dubbed hydrophilanthropy. (See PDF of Kraemer’s 2010 article in the Journal of Contemporary Water Research and Education.) “Solutions to global clean water problems are achievable,” said Kreamer. “I think people who are involved in water have a natural proclivity to be philanthropic.” Kraemer reached out to colleagues at the biennial meeting of a unique group fostering collaborative work on water issues. The NSF-sponsored Consortium of Universities for the Advancement of Hydrologic Science (CUAHSI) includes more than 100 colleges, universities, and other institutions. Its major products include online data catalogs, open source software, and the biennial meeting, which is hosted by UCAR every other summer in Boulder. Dozens of researchers gave talks and presented posters in July at this year’s meeting. Keynote speakers included Roger Pielke Jr. (University of Colorado Boulder), Soroosh Sorooshian (University of California, Irvine), and Tom Dunne (University of California, Santa Barbara). “At the high latitudes and the low latitudes, we’re actually seeing increasing water tables,” says Jay Famiglietti, who directs the Hydrology & Climate Research Group at the University of California, Irvine. At the same time, he adds, “Most of the aquifers in midlatitudes are under huge stress.” (See “Reservoirs beneath our feet.”) Glaciers will also feel the pinch of a warming climate, although there are many questions about how quickly an increase in glacial melt might segue into eventual depletion for the millions who rely on glaciers as a primary or supplemental water source. (See “Who needs glaciers?”) How will we manage? As water managers contemplate the future, they’re paying close attention to where efficiency and conservation can make the biggest gains. A new global outlook by the National Intelligence Council predicts that nearly half of humanity will live in water-stressed regions by 2030. Globally and nationally, agriculture gulps more water than any other part of society, making up roughly 80% of water consumption. A single farmer atop the Ogallala Aquifer of the High Plains may draw on as much water as a good-sized city. The ongoing global rise in meat eating is expected to put additional strain on water resources, since it typically takes more water to produce a calorie of meat versus one of grain. The energy sector accounts for an estimated 27% of nonagricultural U.S. water use, as noted in a 2010 Harvard report. Aside from the large amounts of water required to grow corn for ethanol, water is pumped through coal plants and nuclear reactors to keep them cool. Much of that water returns to source streams, albeit at higher temperatures than before. Large amounts of water are also pumped into the ground to squeeze out oil and natural gas, through the technique known as fracking (hydraulic fracturing). This year’s drought is already putting a crimp on the hydrocarbon boom in some U.S. states. For the public, water utilities are the most familiar part of the supply chain, especially when customers are asked or required to restrict water use during dry periods. Through his work with a variety of clients from Florida to California, NCAR’s Yates has seen what happens when finite supplies go head to head with development pressures. “It’s hotly political. People want to build,” he says. However, he believes the intensity of recent droughts, together with rising demand, is starting to engender more caution: “I think the utilities are questioning their assumptions.” David Yates (©UCAR. Photo by Carlye Calvin.) A utility-based alliance is now helping bring water providers into the loop on climate research. (See ”Keeping the tap flowing.”) Yates and NCAR economist Kathleen Miller published a guide (see PDF) to help drinking water utilities anticipate how climate change might affect supply and demand. And Yates collaborated with Denver Water and consulting firm Riverside Technology on a report released in March by the Water Research Foundation. It examines the potential impacts of climate change on water supplies in Colorado’s populous Front Range region, using two different hydrology models. The NCAR-based Colorado Headwaters project is also producing new detail on how precipitation may evolve in the high mountains that feed the Colorado River. (See ”Three state of water.”) Colorado offers a useful window into the complexities of water projections, according to Brad Udall. He directs the Western Water Assessment, one of NOAA’s seven Regional Integrated Science and Assessment groups. “We get affected by weather from all points on the compass,” says Udall. “We’ve got these big mountains and summer monsoonal flow. All of these things are difficult to resolve in our current models.” Stir in climate change, and this detailed portrait morphs into a motion picture. “When a lot of people talk about climate change adaptation, they say, Give me a target and I’ll plan for it. That doesn’t appreciate the fact that the target is going to move throughout the 21st century.” As a rule, says Udall, “We don’t deal very well with moving targets.” Kevin Trenberth (©UCAR. Photo by Carlye Calvin.) A global eye on energy and water cycles The world’s most comprehensive program to outline the flow of heat and moisture through Earth’s atmosphere is heading in new directions. Formerly the Global Energy and Water Cycle Experiment, GEWEX is now Global Energy and Water Exchanges. Adopted in July, the new name reflects the broadening nature of the group’s work. “We recognized that the old name was obsolete—we are no longer an experiment,” says NCAR’s Kevin Trenberth, who chairs the GEWEX scientific steering group. GEWEX is in its 25th year as part of the World Climate Research Programme, with an international project office supported by NASA and located in Silver Spring, MD. Drawing on support from a variety of participating nations, GEWEX fosters collaborative field projects, workshops, dataset development and assessment, and other activities to bolster research on water and energy cycles, with the ultimate goal of reproducing and predicting global hydrologic processes and their effects. As part of an overall revamp of the parent program toward research that supports climate services, GEWEX has adopted a new set of seven imperatives, as well as four grand science questions: How can we better understand and predict precipitation variability and changes?  How do changes in land surface and hydrology influence past and future changes in water availability and security? How does a warming world affect climate extremes, especially droughts, floods, and heat waves, and how do land area processes, in particular, contribute?  How can understanding of the effects and uncertainties of water and energy exchanges in the current and changing climate be improved and conveyed?  

Three states of water

August 13, 2012 | From ocean to ocean, the relationships between individual states and their water supplies are changing. Climate scientists have projected serious regional changes over the next 50 years, but many states are already having to make tough decisions regarding their water use and their interaction with water. Among them are Colorado, Louisiana, and Oklahoma. NCAR scientists are involved in collaborative projects in all three states to evaluate the long-term effects of today’s decisions. Along the Colorado From its high-altitude origins just west of the Continental Divide in the Colorado Rockies, the Colorado River flows onward, providing water for cities and farms throughout much of the southwestern United States. (Photo by Bonnie Carol.) Recent statewide fires have moved Colorado residents to ask hard questions about the future of water and drought in the state. Models project that the warming atmosphere will change the character of winter storms in the Rocky Mountains, affecting residents and farmers across the Southwest who rely on the storms as their primary water source. Snowmelt from the high peaks of the Rockies provides more than 80 percent of the water flowing downstream to major cities, including Phoenix and Las Vegas. To better understand how winter storms will be affected by changes in climate, scientists at NCAR’s Research Applications Laboratory are working to perfect the modeling of precipitation, snowpack, snowmelt, runoff, and other variables in the high-altitude basins where the Colorado River begins its southwestward trek to the Pacific. NCAR's Roy Rasmussen heads the interdisciplinary team behind the Colorado Headwaters Project. (© UCAR. Photo by Carlye Calvin.) Dubbed the Colorado Headwaters Project, this team of 15 people led by Roy Rasmussen is made up of atmospheric and social scientists and engineers. It also collaborates with researchers at the University of Colorado Boulder, the University of Washington, and the University of Texas at Austin. The goal is to better understand how the complex terrain of the Rockies affects rain and snow on the small scale, and to incorporate that knowledge into larger-scale projections from climate models going decades into the future. The team used the advanced research version of the Weather Research and Forecasting model (ARW), which reproduced snowfall and other weather variables for four winters from the last decade with high accuracy at points separated by as little as 5 kilometers (about 3 miles). They also drew on results from the NCAR-based Community Climate System Model (which is supported by NSF and the U.S. Department of Energy). Those results indicated that the region’s climate would see a 3.6ºF (2ºC) increase in temperature and a 15% increase in precipitation over recent conditions by 2045–55 if global emissions of greenhouse gases continue to increase at a moderate pace. The group then used the CESM estimates with ARW to determine what would happen on a finer scale. Colorado’s famed terrain produces wide variations in rain and snow across small areas. To better reproduce these patterns in weather and climate projections, the Colorado Headwaters effort is employing high-resolution models that depict major peaks, ridges, and valleys across the state. (Image courtesy Colorado Headwaters project.) The results showed that snowfall increased overall by 12% at midcentury compared to the past decade. However, the results varied by altitude: snowpack increased at the highest elevations and decreased at lower elevations. "Our results show islands of enhanced snow in the highest Colorado peaks, surrounded by areas with more rain and melting," says Rasmussen. Spring melt occurred three weeks earlier than today, and the snowline elevation increased by an average of 660 feet (200 meters). Shifts in runoff and evaporation were also projected. Future studies will consider changes in storm tracks. These findings suggest that different cities will be affected different ways. In states such as Arizona, the changes could mean severe drops in water access; in Colorado, the results suggest a shorter snow season and a snowpack that melts and evaporates more quickly, even with the potential for heavier snow at the highest elevations. David Gochis, an NCAR scientist who works on the project, puts things into perspective from a water-management point of view: “We will still face significant challenges in water management. There will be more evaporation and more pressure on water supplies, particularly in the summertime,” he adds. Coastal concerns At the northern end of Isle de Jean Charles, 30 families of the Biloxi-Chitimacha-Choctaw tribe hold on to land threatened by environmental and commercial pressures. Extending from the top right of the photo is Island Road, the only means of getting to the island from the mainland. (©UCAR. Photo by Monika Wnuk.) On the other side of the Continental Divide, waters from eastern Colorado and many other states flow into the mighty Mississippi, eventually spilling into its famed delta in far southeast Louisiana. Here, the rapidly changing coast tells a complex water story pertinent to coasts everywhere. Hurricanes Katrina and Rita brought attention to the delta’s vulnerability to natural forces, but the daily vulnerability of the coast to geologic and human activity is talked about less often. Natural buffers against storm surge have long been a function of barrier islands, healthy marshes, natural ridges adjacent to bayous, and cypress swamps. In combination with artificial levees, these landscape features have allowed humans to live and work in an otherwise flood-prone area. However, society has also jeopardized the ability of the landscape to repair itself. Land subsidence (sinking) coupled with a rise in sea level have exacerbated erosion and allowed destructive storm surges to penetrate the coast and move further inland. When humans are not affecting the landscape, then river deltas can work to both erode and replenish barrier islands in a cyclic fashion. However, levees built to divert sediments away from Louisiana’s coast haven’t allowed for this cycle to unfold. Moreover, decades of oil drilling have left open pipelines underwater that encourage the flow of salt water into delicate wetland ecosystems. Unaccustomed to saltwater, entire cypress swamps decay along the coast, further contributing to flooding and erosion. NCAR’s SOARS program (Significant Opportunities in Atmospheric Research and Science) sent two students to Louisiana this summer to investigate this multifaceted water issue. See the sidebar at the bottom to dive deeper into the specifics of their community-based research. Drought in a boom-and-bust water regime Only months after heavy winter rains erased a severe drought, Oklahoma returned to record heat and bone-dry conditions in the summer of 2012, paving the way for destructive wildland fires. A fire just east of Norman on August 3 spawned this pyrocumulus cloud, photographed from the roof of the National Weather Center. (Photo courtesy James LaDue, NOAA.) Where Louisiana looks to mitigate the effects of too much water, Oklahoma struggles to make sense of year-to-year variability in precipitation. “There is nothing steady about rain in Oklahoma,” says Jeffrey Basara, director of research at the Oklahoma Climatological Survey. Basara recalls periods of significant drought in 2000, 2006, 2011, and 2012 and how sharply they contrasted with extreme rainfall events like the record-breaking flash flood in Oklahoma City in 2010. Such variability on short time scales calls attention to future water sustainability in the state.  In Oklahoma, aquifers provide most of the water distributed to homes and businesses. The Arbuckle Simpson Aquifer, located in the south-central part of the state, is the only source of water that supports the various streams, rivers, and lakes in a 500-square-mile area, supplying a total of 39,000 users. Ownership and limits to use of the aquifer are now being disputed by a mix of parties, including landowners who wish to sell the water to neighboring states, a group of citizens concerned about preservation and sustainability of Oklahoma’s water supply, and members of the Chickasaw Nation who claim original rights to the source. Since 2003 the aquifer has been studied more intensively than any other in the state. Shown here in light brown, the Arbuckle-Simpson Aquifer is located in south-central Oklahoma. (Map courtesy U.S. Geological Survey.) Scientists in NCAR’s Earth System Laboratory (NESL) are using an interdisciplinary approach to chart how people value water and perceive drought risk in south-central Oklahoma and whether this lines up with climate projections for future water availability. Environmental anthropologist Heather Lazrus is teaming with climatologist Debasish PaiMazumder and ecosystem scientist Erin Towler on the project. NCAR's Heather Lazrus brings an anthropological perspective to an interdisciplinary study of water use in Oklahoma. (©UCAR. Photo by Carlye Calvin.) Based on a foundation of anthropological theory, Lazrus is conducting and analyzing interviews in hopes of illuminating the cultural mechanisms through which people understand water-related risk. PaiMazumder is using NCAR’s Nested Regional Climate Model to develop plausible drought scenarios in Oklahoma’s current and future climates through an exploration of drought impact indices (mainly precipitation, temperature, and soil moisture). And Towler is analyzing stream flow patterns in wet and dry years to understand the impact of drought. Using Lazrus’s findings on how people view water availability and drought risk, PaiMazumder will develop a new index for assessing the damage caused by droughts. The results will be made available to water planners and the public. Also, Towler will identify impacts to drinking water, fishing, and other ecosystem components that rely on water availability. “Our hope is to communicate the potential of drought in a way that parallels how people understand it,” says Lazrus. Monika Wnuk, a recent graduate of the University of Chicago, was an intern with NCAR & UCAR Communications in the summer of 2012. SOARS protégés lead research in the bayou A human issue accompanies the changes in land and water use in coastal Louisiana, where economically vulnerable populations live For her 2012 research as a UCAR SOARS protégé, Sandra Maina (Florida International University) worked with residents of far southeast Louisiana and conceptualized a smartphone application to depict the science and the human stories behind their sinking landscape. (©UCAR. Photo by Monika Wnuk.) on land that is in immediate danger. Among these groups is the Biloxi-Chitimacha-Choctaw Native American tribe residing on the island of Isle de Jean Charles. Forced by westward expansion in the 1800s onto the southernmost part of the Mississippi Delta, this tribe struggles to hold onto the land that has long sustained it. Out of a population of 80 families a decade ago, the remaining 30 families of Native American descent live on a two-mile strip of land on either side of one road, surrounded by land that has become too soggy for use. Residents can only point to where their family’s cow pastures, forests, and cemeteries used to be. A four-foot dirt levee separates their homes from the Gulf of Mexico. Residents drive almost daily to the mainland on a low-lying road that tends to flood. But relocation would be expensive, and there are other factors keeping the remaining families in place. For example, the region is considered a fishing paradise, and tribal members are constantly at odds with fishermen who set up camps on the island. Through UCAR’s SOARS program (Significant Opportunities in Atmospheric Research and Science), Sandra Maina, a graduate student in environmental studies at Florida International University, and Frances Roberts-Gregory, a senior in environmental science and anthropology at Spelman College, spent the summer of 2012 conducting interdisciplinary research in this vulnerable community. Maina and Roberts-Gregory were introduced to local issues by their community mentor, Kristina Peterson, a research associate at the University of New Orleans Center for Hazards Assessment, Response and Technology. Peterson is deeply invested in the community, serving as a pastor at the local Bayou Blue Presbyterian Church and as an activist for the region at conferences across the nation. Following the guidelines of participatory action research, Maina and Roberts-Gregory asked members of the community to express their needs, then designed their projects accordingly. Maina met with community members on the five most vulnerable strips of land along the coast—Chauvin, Dulac, Dularge, Montegut, and Pointe au Chien—in order to identify points of cultural interest that are at risk of flooding and erosion. Following her summer of fieldwork, she hopes to direct the creation of a smartphone application that would map these places and include a history of each one, along with a video message from a community member. The app would also keep users updated on ongoing restoration projects in the area. Even some homes and business that were built on stilts to accommodate flooding are now difficult to access at any time. (©UCAR. Photo by Monika Wnuk.) “Lots of big organizations want to exclude the community,” says Maina. “This smartphone app seeks to include and empower it.” Roberts-Gregory applied tools from ethnobotany and anthropology to determine which culturally significant plants are threatened by ecosystem changes. Her procedure started with documents from the 1930s that details curatives used by Native Americans in the area, supplemented with conversations with community members who work with the same plants. Roberts-Gregory describes her experience with participatory action research as “just as complex as the water situation in Louisiana.” Every week brought new conversations, focus groups, content analysis, and new angles to the issues at hand. Although the process took time, she sees community input as essential to community-relevant results. Both students hope that future scientists continue community-based interdisciplinary projects in the region. From what they’ve seen, residents know the issues and are eager to continue the conversation—and move into action.

Reservoirs beneath our feet

August 13, 2012 | One of the largest bodies of water in the United States can’t be seen from the air. It stretches from Nebraska to Texas, and it helps produce $35 billion in wheat, corn, and other agricultural products each year. But the vast Ogallala Aquifer isn’t on the radar of Rand McNally or Google Maps, because it lies underground. The Gravity Recovery and Climate Experiment (GRACE) measures changes in the mass of water and other Earth-system components by tracking tiny changes in the gravitational pull exerted on its twin satellites. (Image courtesy Astrium.) The Ogallala is part of an array of aquifers around the world that help provide food, water, and energy for millions of people. Much like oil and gas reserves, the bounty of an aquifer can seem endless until its flow begins to slacken. A revolutionary satellite system is giving scientists a far better idea of where aquifers are being depleted the most quickly—vital data for helping manage these enormous but ultimately limited resources. The twin satellites known as GRACE, the Gravity Recovery and Climate Experiment, have been tracking Earth’s gravitational field in detail since 2002. Led by German science agencies, NASA’s Jet Propulsion Laboratory, and the University of Texas at Austin, GRACE measures tiny gravity-induced changes in the tracks of its satellites, which allows scientists to infer changes over time in ocean currents, glaciers, and other geophysical features.  “GRACE has shown us that the human fingerprint on the water landscape is extremely strong,” says Jay Famiglietti, who directs the Hydrology & Climate Research Group at the University of California, Irvine.  A GRACE-ful approach Famiglietti is part of a group of scientists who’ve spent years unraveling GRACE data to deduce how aquifers are changing. The only sure way to verify an aquifer’s depth at any given point is to drill into it. That’s been done courtesy of some 9,000 wells tapping into the water of the Ogallala, which is among the world’s best-characterized aquifers. The depth and volume of many other aquifers isn’t known. But GRACE can monitor changes even without knowing an aquifer's total storage. Satellite data suggests that depletion of northern India's aquifers has continued since NCAR’s Sean Swenson and colleagues published a 2009 analysis. The map above shows the change in total water storage as measured by the GRACE satellite between 2002 and 2012. The graph shows trends for the strongly depleted area in northern India within the box outlined on the map. Year-to-year changes in the monsoon play a large role in the rate of aquifer use, along with increased development and other factors. (Images by Sean Swenson, NCAR.) “We already knew that groundwater is being depleted in these aquifers,” says Famiglietti. “GRACE allows us to quantify the rates of depletion, which is very difficult to do on the ground and almost impossible to do internationally.” Sean Swenson. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.) When NCAR’s Sean Swenson was a graduate student at the University of Colorado Boulder, he developed techniques to reduce errors in GRACE data and greatly improve its spatial resolution. Swenson now focuses on development of NCAR’s Community Land Model, but he’s often asked to participate in GRACE-related research. In 2009, Swenson collaborated on a study led by V.M. Tiwari (National Geophysical Research Institute, India) concluding that groundwater in northern India had been depleted by roughly 54 cubic kilometers (13 cubic miles) per year between 2002 and 2008, perhaps the most rapid loss on Earth for an area that size. “This is probably the largest rate of groundwater loss in any comparable-sized region on Earth," the study noted. With India’s monsoon weaker than normal this year, it’s been suggested that the energy associated with aquifer pumping helped trigger power outages that affected hundreds of millions of people across northern India in late July. Swenson and Famiglietti are collaborating on another study, now in review, examining groundwater depletion in a drought-prone area spanning parts of Turkey, Iraq, and Iran. Swenson is also working with Famiglietti’s former Ph.D. student, Min-Hui Lo (National Central University, Taiwan), to develop models of aquifer loss that GRACE and other data can help verify.  Wells that won’t do so well This map shows the locations of major aquifers in the contiguous 48 states. The Ogalalla Aquifer is shown in pale blue, stretching from Nebraska south to Texas. California’s Central Valley aquifer system is shown in darker blue at far left. (U.S. National Atlas map courtesy Mission 2012: Clean Water.) Within a single aquifer, there can be enormous variation. A recent study led by Bridget Scanlon (University of Texas at Austin) analyzed depletion rates for the Ogallala and for the aquifer system that supports agriculture across California’s fertile Central Valley. The Ogallala’s situation is the more dire of the two. The north end of this aquifer, beneath western Nebraska, is replenished by water descending from the Platte River system through sandy soil. Here, irrigation demands are relatively modest. Further south, there’s very little recharge from surface water, and fine-grained soils help keep rain and snow from percolating downward. Some of the “fossil” groundwater used to irrigate crops in western Kansas and Texas may date back to the last ice age, more than 13,000 years ago. Corn stalks from the previous year’s harvest lie atop parched fields in northeast Colorado in early June 2012. Many of the crops grown in the region rely on irrigation from the vast Ogallala Aquifer. (©UCAR. Photo by Bob Henson. This image is freely available for media & nonprofit use.) Extrapolating from recent depletion rates, Scanlon and colleagues found that some parts of the southern Ogallala may essentially run dry within the next 30 years. That doesn’t necessarily doom farmers; only about 30% of the region’s crops are irrigated, and many farmers would shift to less-thirsty crops as needed. However, the overall stress on water supply would undoubtedly soar. At Michigan State University, Bruno Basso has been examining the effects of Ogallala depletion and climate change on agriculture. He is also investigating the potential impact of adaptation strategies farmers could use to improve soil quality, crop yield, and water use efficiency. The strategies studied by Basso include using water-sipping no-till techniques, optimizing the mix of plants, altering planting dates, and employing new cultivars not yet developed but simulated in crop modeling. These approaches could help keep crop yields from plummeting, says Basso, although he stresses that economic and climatic uncertainties will shape how farmers ultimately act. As opposed to the Ogallala, there's more flexibility in managing water across California’s Central Valley, where rain and snowmelt from the Sierra Nevada helps recharge the aquifer system. Since the 1960s, a set of groundwater banks built within the Tulare River basin has gathered water during wet years and sent it underground, to be pumped back up as needed during dry years. In the Central Valley, “Groundwater banking offers great promise for more sustainable management of groundwater," the study by Scanlon and colleagues concludes. Yet climate change remains a question mark for central California’s aquifers. If precipitation simply became more variable, without increasing or decreasing in the long term, then groundwater banking would be well suited for adapting to that shift. But putting water underground and pulling it back out is an energy-intensive endeavor. And it’s possible that the total amount of rain and snow might decrease, especially toward southern parts of the state. Water expert Jay Famiglietti (University of California, Irvine) is conducting a 50-lecture tour this year sponsored by the American Geophysical Union. (©UCAR. Photo by Bob Henson. This image is freely available for media & nonprofit use.) There’s no doubt that on-and-off drought since around 2000 has taken a toll on water supplies across the U.S. Southwest, including lakes Mead and Powell, which were running at 50-60% of capacity in recent weeks. In a 2011 study, Famiglietti and colleagues estimated that the aquifers beneath California’s Sacramento and San Joaquin River basins had lost nearly enough water in seven years to fill Lake Mead. Beyond the concerns in his own part of the world, Famiglietti is communicating about global pressures on water access in several ways. Later this year, he plans to publish the first GRACE-derived global map of aquifer trends. Right now Famiglietti is in the midst of a 50-week, 50-lecture global tour called Water 50/50, supported by the AGU’s Birdsal-Dreiss Distinguished Lectureship. He’s also one of the featured scientists in a major documentary on water issues, Last Call at the Oasis, released earlier this year. Among his key messages in the film is a call to map out Earth’s water resources as thoroughly as its oil and gas resources have been charted. “Nationally and internationally,” he says, “we need to push for a thorough exploration of Earth’s water environment.”

Who needs glaciers?

August 13, 2012 | The Andean nation of Bolivia doesn’t have a very large carbon footprint. The country covers an area the size of Texas and California combined, yet. it’s home to fewer than 11 million people, most of whom are subsistence farmers. But Bolivia is already experiencing the effects of climate change as its glaciers shrink, putting water supplies at risk. Though the ski lift remains, the glacier that provided decades of skiing atop Bolivia's Chacaltaya peak disappeared in 2009, succeeded only by snowfalls such as this one in early 2011. (Wikimedia Commons image by DiverDave.) “Bolivia is a pretty dry place,” says NCAR scientist David Yates. The slow decline of the glaciers there is a concern because, as Yates points out, these storehouses of ice supply about 20 percent of the water used by major Bolivian cities such as La Paz and Santa Cruz. It’s not yet clear how Bolivia will adapt to the gradual loss of its glaciers, but Yates’ work on water planning will help that nation determine its response. Yates is part of a team based at the Stockholm Environment Institute that’s developed an interdisciplinary model called WEAP to help cities and regions evaluate their water resources and plan for the future. “By incorporating a glacier model into our water planning model,” he says, “we’re able to answer questions like, What is the reliability of these glacial resources over the next 50 to 100 years? and What kind of investments can be made now to secure the water supply in the future?” NCAR's Kathleen Miller specializes in multidisciplinary topics, including the evolving nature of water management in the context of a varying climate. (©UCAR. Photo by Carlye Calvin.) Bolivia is one of many nations around the world where people depend on glaciers for fresh water. Most of the world’s ice is locked in the vast sheets of Greenland and Antarctica; it’s the smaller glaciers in the midlatitudes and tropics that provide water for people. This is where global ice is melting the most quickly, and the situation is drawing increased concern from policymakers and researchers alike. “Everybody will need to understand what risks they face in their particular localities,” says NCAR’s Kathleen Miller, an economist who specializes in climate issues. Budgets out of balance In contrast to the vast, remote ice sheets near the poles, mountain glaciers that provide water for human populations are especially sensitive to warming temperatures. At high elevations, where the air is generally colder, glaciers gain mass from falling snow. At lower elevations, where temperatures are warmer, glaciers lose mass through melting, which provides water used by glacier-dependent areas. This balance of gain versus loss changes throughout the year, as patterns of precipitation and temperature change. However, as a rule, a glacier is stable when snow and melt are equal. A small change in temperature can easily alter this balance and push a glacier into shrinking mode. Warmer air can also turn ice directly from frozen to vapor form without melting, a process called sublimation. In line with the measured warming of the global atmosphere, most of the world’s glaciers have been losing mass on average for the last century or so, with the pace quickening over the last couple of decades.  That trend is expected to continue with increasing concentrations of greenhouse gases and continued warming. Given these trends, says glaciologist Richard Alley (Pennsylvania State University), “we have high confidence that there will be a whole lot of glacier loss.” One of the world's most prominent glaciologists is Richard Alley, based at Pennsylvania State University. (Image courtesy Oregon State University.)  But there are many unknowns when it comes to the details of glacier science. Specialists are trying to get a handle on how fast glaciers will disappear, which ones will go first, and how that will affect water supplies. It’s often not even clear exactly what fraction of the water used by societies is drawn from glaciers, both on the global and local scale, although in South America alone, millions of people are believed to rely in part on glacial water. For any given location, “glaciers aren’t the only source of water,” Miller explains. “Annual precipitation is often the primary source, while glacial melt becomes important during drought years and in late summer, after the annual snow pack has melted.” Glacier science is made even more difficult because not all glaciers act the same. They inhabit different locations, with different topographies beneath them and different climates surrounding them. And while climate change will lead to generally higher temperatures around the globe, it is far more difficult to predict the range of local temperature variability, and changes in precipitation can be even more challenging to project. Some glaciers may actually grow if they receive more snow than they do now, despite rising temperatures. That uncertainty and variation have often led to misinformation about the future of glaciers, particularly in the media. “A lot of the confusion that’s come up in the last several years is largely from generalizations,” says glaciologist Richard Armstrong (University of Colorado Boulder), who studies Himalayan glaciers. In this region alone, he points out, “there’s huge variability from east to west.” On the Tibetan plateau, for example, scientists have documented a recession of the glaciers that feed the Yangtze River in China. However, glaciers in the Karakoram Mountains along the Pakistan-China border grew slightly between 2000 and 2008. There’s a similar east-west contrast in how people use glacial water from the Himalayas, according to Armstrong. River basins in the east, such as the Ganges, are dominated by monsoons, and glaciers supply only about five percent or less of the water used there. Further west, in the mountains of Pakistan and Afghanistan, perhaps as much as half of the water supply comes from glaciers. As a whole, the Himalayas are losing ice, although not nearly as fast as stated in the Intergovernmental Panel on Climate Change’s Fourth Assessment Report in 2007. The report included a claim that failed to meet the IPCC’s requirements for scientific peer review. Based on a single magazine interview, the erroneous claim asserted that Himalayan glaciers would disappear by 2035. When the error and its source were identified, the IPCC issued a retraction. In that statement, the panel stressed that the findings in its overarching synthesis report remained valid: “Widespread mass losses from glaciers and reductions in snow cover over recent decades are projected to accelerate throughout the 21st century. . . . This conclusion is robust, appropriate, and entirely consistent with the underlying science and the broader IPCC assessment.”  Despite some decade-to-decade variation, the amount of water trapped in the world's glaciers decreased nearly every year from 1945 to 2005. (Fig. 5.9 from Chapter 5 (PDF) of Global Glacier Changes, courtesy United Nations Environment Programme.)  As Penn State’s Alley points out, “The basic picture is: warming melts ice. Is it possible to find an exception? Yes. Do you find lots and lots of exceptions? No.” Saving for a dry day The loss of glaciers will be felt particularly in river basins that depend heavily on them for meltwater. As glacial melt increases, it can release hundreds or thousands of years of locked-up water. The tap may flow more freely for a time in glacier-dependent communities. But in the longer run, glacial water will inevitably become less available, putting supplies for drinking, agriculture, and hydropower at risk and causing societies to consider water use more carefully. The Andes are home to the majority of the world’s tropical glaciers, which have been melting faster than any others, as documented by Lonnie Thompson (Ohio State University) and other pioneers of tropical glaciology. Some of these low-latitude ice stores are already completely gone. The mountain of Chacaltaya in Bolivia, for example, was home to the world’s highest ski lift for half a century. But after years of loss, the Chacaltaya glacier disappeared in 2009. According to Edson Ramírez (Universidad Mayor de San Andrés, Bolivia), it was a drop in snowfall rather than a rise in temperatures that sealed Chacaltaya’s fate. A similar process, driven by drying rather than warming, appears to be the culprit behind the loss of ice atop Mt. Kilimanjaro in Africa. Such reductions in tropical snowfall may themselves be related to large-scale warming and associated changes in atmospheric circulation, a topic of active research. La Paz, Bolivia, is among the world’s cities most dependent on water from glaciers. (Wikimedia Commons image by Wayne McLean.) More than skiing is at risk with the loss of Andean glaciers: the depletion may increase water costs and impair local economies. Hydropower, which provides 80 percent of Peru’s energy, 50 percent of Ecuador’s and nearly all of the electricity in the Bolivian capital of La Paz, could become less available, leading to higher energy prices or rationing. The full scope of the threat is not yet known, though. “One problem we have in the Andes is that the database we work with is very, very poor,” says climate scientist Mathias Vuille (University of Albany, State University of New York). “There are not enough weather stations in the region, and there has not been a good maintenance of these stations.” Andean nations tend to be poor and lack their own scientists, and many have undergone social upheaval that has interfered with glacial studies. The research now taking place in Andean nations will help to guide adaptations to the loss of glacier-based water supplies. The project that NCAR’s Yates is working on in Bolivia, for example, will inform the Inter-American Development Bank on how to invest in infrastructure projects, such as reservoirs, watershed management, and reforestation, so that money is wisely invested. “If there’s no water to fill a reservoir, you’ve just spent a bunch of money, probably had environmental impacts, and put a reservoir in a place where it won’t meet its objectives,” Yates says. A census of ice Glacier modeling, too, will aid in better assessments. The task of modeling glaciers in large numbers has been made much easier by the release earlier this year of the National Snow and Ice Data Center’s Randolph Glacier Inventory, which provides surface areas for most of the world’s estimated 160,000 glaciers as well as the locations for many of the world’s smaller glaciers and ice caps. With this in hand, scientists can compensate for many of the variations and unknowns in glacier science. For example, with a solid estimate of global glacier surface areas, scientists can estimate the volume of ice contained in these ice masses, and potentially model changes to this volume using climate models. “Glacier ice is a viscous fluid, and we know how it operates,” says Jeremy Fyke, a glacier modeler doing postdoctoral research at Los Alamos National Laboratory. “If you pour pancake batter onto a surface, you can generally figure out how thick that pancake is if you look at its area. It’s sort of the same thing with glaciers.” But modelers say they would still benefit from knowing more about the topography of the bedrock beneath glaciers and about the climate surrounding them. “A lot of these glaciers are in remote places,” Fyke notes. “They’re not cheap places to go and take measurements.” Some measurements can be taken from space—the glacier inventory, for instance, primarily used data from NASA’s Terra satellite—“but that’s sometimes inadequate,” Fyke says. “The science is improving every year, but local changes in precipitation and resulting changes in water supplies and glacier mass-balance can’t be known yet,” says NCAR’s Miller. However, she adds, that need not stop the process of preparing for a reduced water supply from glaciers. “Trying to develop a contingency planning approach will help nations respond well to any change that manifests itself.” Sarah Zielinski is a freelance writer based in Washington, D.C.

Keeping the tap flowing

August 13, 2012 | A longtime environmental leader and water policy expert, David Behar is one of the nation’s leading voices on how to weave weather and climate knowledge into water management. He currently serves as climate program director for the water enterprise at the San Francisco Public Utilities Commission, which is the nation’s sixth largest municipal water provider. In 2007, he organized a summit that evolved into the Water Utility Climate Alliance. This coalition of 10 large utilities from across the nation works to foster collaborative research and to help water utilities mitigate and adapt to climate change. Behar is also involved in a pilot project on tailoring climate model output for water management, an effort organized by the new societal dimensions working group of the NCAR-based Community Earth System Model. (Photo courtesy David Behar.) How is climate change viewed by the nation’s water managers? I think it’s increasingly seen as an important part of understanding how to operate our systems in the future. The larger drinking water providers in the country are leading the way, but there are a number of smaller agencies, here in California and elsewhere, that have done some very thorough and sophisticated work in assessing the impact of climate change on their systems. What climate change means is that past practice is no longer a good indicator of how we need to view the future. In the water business, we traditionally look at the stationary hydrologic record and use it as the boundary for how we might operate in the future. We know we can’t do that anymore. The vulnerability in the Southwest United States is completely different than the vulnerability in the Northeast. In my region, central California, we’re on the coast and most of our water comes from the Sierra. We’re concerned about upward trends in temperature, particularly minimum daily temps, and we’re concerned about possible changes in precipitation. To a degree, the climate models are still providing mixed signals on precipitation in our region. That makes planning and thinking and assessing more difficult than if there’s a clearer signal emerging. Also, there’s a diversity of political frameworks in which people operate. In some places, if you’re not acting now with respect to climate change, your constituents will think you’re falling behind. In other places, it’s sometimes difficult to even use the words “climate change,” because of the politicized nature of this issue. So one size absolutely does not fit all when it comes to effects, assessment techniques, or the politics of climate change. What are the most recent trends in U.S. water supply? Water demand has plummeted nationwide over the last three years by about 10 to 20 percent. Here in the Bay Area, it’s down by 15 to 20 percent. It’s actually resulted in a financial crisis for water districts everywhere. Water use is where our revenue comes from, and we have high fixed costs, so we’re sensitive to fluctuations. Nobody really knows why this is happening, but it may be a mix of three factors. One is the economy, which is creating price elasticity for water—which is a very cheap commodity—along with causing vacancy and foreclosure rates that can drive down water consumption. The second factor is weather, especially in California, where we’ve had a series of unusually cool summers. The third factor is the conservation ethic, which is penetrating to the public after a lot of education over a lot of years, even in a non-drought context. The economy may be the main factor. Usage is going back up this year in many places, but I don’t know if it qualifies as a reversal of the trend. How is climate influencing current decisions on water infrastructure investment in San Francisco and nationwide? Our bayside storm collection system is already being affected by rising sea level. We're investing $20–40 million to deal with these effects. It’s one of the only examples in the United States where climate-justified adaptation planning and spending is under way. By and large, we’re still in an era of assessment rather than adaptation in the United States. Here in the Bay Area, we’re in the process of trying to figure out what we know, what we don’t know, and what it all means. Do you think California’s experience with a highly variable water supply helps prepare the state for future climate impacts? We like to say that water managers know uncertainty. We deal with it every day, every month, every year. Weather is a subset of climate, and in the West, each year’s weather can be very different than the year before. We know how to operate with drought, but the drought we plan for is our drought of record. It’s consecutive dry years that create the greatest vulnerability for the greatest number of people. Understanding how those are going to change is really important. A lot of people have used the paleoclimate record to envision droughts that could last 20, 30, 40, or 50 years. There’s no way to prepare for a drought like that in terms of infrastructure. We are used to changing conditions year over year, but I sometimes refer to the qualitiative paradox that emerges from climate science. We hear that extreme events will get more extreme, droughts will get stronger, intense storms will get more intense, but we don’t know by exactly how much. We’re left with a qualitative projection of the future that is difficult for us to plan for, because we’re engineers, and the amount of molecules of water in our reservoir at the end of each year is what ultimately matters. In snowfed watersheds like ours, the timing of runoff changes as a result of temperature changes, because more precipitation falls as rain and the snow melts sooner. At my utility, we’ve completed a sensitivity analysis that laid out six different scenarios, from optimistic to pessimistic, for temperature and precipitation at three points in time: 2040, 2070, and 2100. Runoff varies widely. If you look out to 2100, we can see an increase in runoff of a few percent, down to a decrease of 29%, depending on which scenario you pick. It’s a very wide range, and it doesn’t lend itself to planning at all. We’re all struggling with how to use the information we have today to prepare for tomorrow. One of the top priorities of the Water Utility Climate Alliance is to build bridges with members of the science community who want to build bridges to us, especially those doing adaptation science. Those scientists are interested in having ongoing, collaborative conversations and building relationships with decision makers like us that will be fruitful over time. We need more of those. 
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