Cooperative Institute for Research in Environmental Sciences

The thin, wispy clouds known as “cirrus” cover nearly a third of the globe and are found high in the atmosphere—5 to 10 miles above the surface. But a new study shows that they typically have a very down-to-earth core, consisting of dust and metallic particles. 

Cirrus clouds are important to global climate because they interact with radiation from the sun and from the earth.  Cirrus are made of ice crystals, but a small “seed particle” is often needed to start the process of forming the ice.  Scientists haven’t known exactly what kind of particles lead to cirrus formation, causing the climate-related properties of the cirrus to be highly uncertain.  A new study published May 9 in Science magazine by researchers at MIT, CIRES, NOAA, NASA, and other institutions has shown that dust and metallic particles are usually at the core of cirrus cloud particles.

“We’ve seen hints of this before, but this study demonstrates that it’s true across a range of geographic locations and a variety of cirrus cloud types,” said Karl Froyd, one of the study’s lead scientists and a CIRES researcher working at NOAA’s Earth System Research Laboratory in Boulder, Colo.  “Cirrus clouds are picky about the kind of particle they form on.  Mineral dust and metallic particles are the most preferred types.”

Other particle types, including mixtures of sulfate and organic carbon, biomass burning particles, elemental carbon, and particles of biological origin were much less efficient as cirrus seeds.

“These results are going to allow us to better understand the climatic implications of these clouds in the future,” said Daniel Cziczo, a scientist at the Massachusetts Institute of Technology and the lead author of the study.  Current global models prescribe a variety of cirrus formation mechanisms, leading to a wide range of cirrus properties and associated climate effects.  This study simplifies the playing field, suggesting that most cirrus form on a special subset of aerosol particles, and that most of those particles are mineral dust and metallic particles.

The scientists used instrumentation aboard high-altitude NASA research aircraft to measure cirrus clouds and seed particles, in flights over Central America and North America from 2002 to 2011.  A special inlet was designed by Froyd to selectively capture ice crystals when flying through cirrus.  After removing the water from the cirrus crystal, Froyd and NOAA-ESRL scientist Daniel Murphy used an instrument known as PALMS (Particle Analysis by Laser Mass Spectrometry) to analyze the residual seed core.  PALMS is a state-of-the-art instrument, originally developed at NOAA by Murphy, that can characterize the chemical composition of particles one by one as they are sampled into the instrument.  “PALMS gives us a detailed chemical fingerprint of each individual particle,” said Murphy.

Also as a part of the study, the scientists used a model to calculate the  atmospheric seed particle concentrations using estimates of the emissions of fine particles from the Earth’s surface, their atmospheric transport, and their ice-forming ability.  “The model results were completely independent of the measurements, yet came to the same conclusions.  This gives us confidence that we’re not missing something important,” said Froyd.

The new study provides many answers about how cirrus clouds form, but also raises new questions.  Is it possible that human activities could affect the amount of dust and metallic particles in the atmosphere, and therefore affect the formation of cirrus clouds?  Mineral dust comes from arid regions such as the Sahara and Gobi deserts, and atmospheric winds carry them across the globe.  Some studies suggest that desertification, land use change, and changing rainfall patterns could account for 10 to 50% of the dust currently in the atmosphere.  Other studies indicate that dust concentrations could increase during this century, perhaps even doubling or more.  The metallic particles found by the researchers are from industrial and combustion sources that have decidedly human influences.

The researchers are now focused on understanding exactly how much mineral dust is in the atmosphere, and where the metallic particles come from.  And, they wonder if their results would hold true in the southern hemisphere.  Most of the large sources of dust and industrial particles are in the northern hemisphere. 

“Cirrus may form differently in the southern hemisphere,” said Murphy.  “That’s one of the next frontiers for this research.”

The authors of the study are from MIT, CIRES, NOAA, NASA, Princeton University, Harvard University, Oregon State University, and the Karlsruhe Institute of Technology in Germany.

                                                                                    —Christine A. Ennis
Karl Froyd, CIRES scientist. 303-497-4766,
Karin Vergoth, CIRES, 303-497-5125,

Last July, something unprecedented in the 34-year satellite record happened: 98 percent of the Greenland Ice Sheet’s surface melted, compared to roughly 50 percent during an average summer. Snow that usually stays frozen and dry turned wet with meltwater. Now, new research led by the Cooperative Institute for Research in Environmental Sciences (CIRES) shows that last summer’s extreme melt could soon be the new normal.

“Greenland is warming rapidly, and such ice-sheet-wide surface-melt events will occur more frequently over the next couple of decades,” said Dan McGrath, a University of Colorado Boulder doctoral student who works at CIRES. McGrath is lead author of a paper published online May 20 in Geophysical Research Letters and which reports a significant warming trend on the Greenland Ice Sheet.

McGrath and his coauthors calculate that by 2025, ice-sheet-wide melt events will have a 50 percent chance of occurring each year. That would signal the loss of the last major dry-snow zone—regions where the snow stays almost perpetually frozen—in the Northern Hemisphere, McGrath said.

In the study, the researchers used air and snow temperature data from meteorological stations and boreholes to generate a 60-year record of air temperatures at the Summit research station, the highest and coldest station on the ice sheet. From 1982 to 2011, near-surface temperatures increased by an average of 0.09 degrees Celsius every year.

“This is six times faster than the global average,” McGrath said.

The warming at Summit is also accelerating. From 1950 to 2011, the average rate of warming was 0.02 degrees Celsius per year. But from 1992 to 2011, that number jumped to 0.12 degrees Celsius per year.

This warming has had a dramatic effect on the ice sheet’s structure, the scientists report. The ice sheet’s ablation zone—the lower parts that lose more snow and ice each year than they accumulate—is expanding up the ice sheet by about 145 feet per year.

“This increases the area over which the ice sheet sheds mass while shrinking the zone that gains mass,” McGrath said. “That will have an obvious impact on the ice sheet’s mass balance.” 

Additionally, the dry-snow line—above which the snow doesn’t melt—is migrating up the ice sheet by about 115 feet per year.

“These zones are indicators of the health of the ice sheet,” McGrath said. “And the changes we are observing are an early but important sign that the ice sheet is in transition.”

The changes could increase the amount of solar radiation the ice sheet absorbs (since wet snow reflects less sunlight than dry snow) and, hence, the melt rate as well. It also could potentially speed up the ice sheet’s flow, though more work needs to be done to untangle these impacts.

These findings are supported by results from other researchers who have found that the ice sheet is losing more than 275 billion tons of ice per year (equivalent to the weight of 750,000 Empire State Buildings). “This imbalance is making a significant contribution to sea-level rise,” McGrath said.

The summit of the Greenland Ice Sheet has experienced surface melt in the past, McGrath says. But the melt events in the past were rare, happening once every century or two—in fact, only eight times in the last 1,500 years—the exception rather than the norm. Now the norm is shifting toward a new, slushy set point.

“Progressive increases in surface melt have occurred throughout the satellite record, but the last decade has been exceptional,” McGrath said. “If each of these events keeps being so far above the average, the average will change to reflect that.”

The scientists’ findings come at a time when Arctic sea ice extent is also at record lows.

“Ice-sheet-wide melting coupled with the loss of Arctic sea ice points to profound changes occurring to the Arctic climate system,” McGrath said. “These are not small, insignificant events we’re witnessing.”

NASA Cryospheric Sciences funded this research, with additional field logistical support provided by NSF Office of Polar Programs. Coauthors include former CIRES Director Konrad Steffen, CIRES adjunct research associate William Colgan, former CIRES doctoral student Atsuhiro Muto, and current CIRES doctoral student Nicolas Bayou. 

CIRES is a joint institute of the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado Boulder.

Dan McGrath, CIRES doctoral student, 303-492-6881,
Katy Human, CIRES communications director, 303-735-0196,

Information and graphics:
Download the photo.

Follow us on Facebook and Twitter: and @CIRESnews.

In 2007 when the extent of floating sea ice in the Arctic was at a record low, how did the resulting large expanses of open water affect regional weather patterns? That's what CIRES researcher Elizabeth Cassano and her colleagues sought to understand in a modeling and observations study published this week. The team found that as sea ice disappeared, the areas of relatively warm open water began to strongly influence the atmosphere, increasing surface temperatures in the region, and shifting low- and high-pressure zones around most markedly in the fall and winter.

Cassano’s co-authors include scientists from Universiy of Colorado Boulder, the National Center for Atmospheric Research and the CIRES National Snow and Ice Data Center

The experiments also indicated that 2007’s summer weather patterns, linked to the large sea ice loss that year, were not forced by sea ice anomalies earlier in the year or during that summer. It is not clear what this means for weather patterns further south, but the work adds to a growing body of literature on the potentially serious effects of dwindling Arctic sea ice.  

The missing link—exactly where the extra methane, a powerful greenhouse gas, is coming from in Los Angeles—has finally been identified, according to a study led by a scientist at NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES). The research explains why the estimates of methane given off by various sources are 35 percent lower than the levels that have actually been measured in the atmosphere by scientists.

“We identified methane sources based on their unique chemical signatures in the atmosphere much like you’d identify a person from their fingerprints,” said lead author Jeff Peischl, a CIRES scientist who works at NOAA’s Earth System Research Laboratory in Boulder, Colo.

Using an innovative experimental technique, the scientists were able to find out that methane quantities coming from activities related to fossil fuels contributed to the discrepancy. Leaks from natural gas (methane) delivery systems in the urban area, geologic seeps such as from the La Brea tar pits, and leaks from local oil and gas exploration activities account for the “missing methane sources” in Los Angeles.

“Our findings can help both industry and the State of California more accurately assess methane emissions,” Peischl said, which would inform the state’s efforts related to climate protection. 

While methane is still only the second-most prevalent greenhouse gas emitted in the United States from human activities, it is more efficient at trapping heat in the atmosphere than carbon dioxide. Pound for pound, the comparative impact of methane on climate change is more than 20 times greater than carbon dioxide over a 100-year period, according to the Environmental Protection Agency (EPA).

Methane is given off into the atmosphere from natural sources, such as geologic sources and wetlands, and from human-related sources, such as landfills, leakage from natural gas systems, and the raising of livestock. In California, the California Air Resources Board (CARB) estimates emissions of methane, along with the other major greenhouse gases, and collates the estimates in the Greenhouse Gas (GHG) Inventory. However, several research studies have discovered that the actual methane released into the atmosphere exceeds those estimates. When Peischl and his team flew over Los Angeles in the NOAA P-3 research aircraft in the summer of 2010, they, too, discovered that the amount of methane emitted in the L.A. area exceeded state inventories—in this case, by 35 percent.

To determine the key contributors to the discrepancy, the scientists then used a novel technique based on the fact that each source of methane typically also gives off other gases in distinctive proportions. Landfills emit methane but not much else, Peischl said, but natural gas supplied to people’s homes and the La Brea tar pits emits mostly methane and then a little bit of ethane and even less propane. “So depending on how much ethane you see relative to methane, you figure out whether it came from a landfill or from natural gas,” he said.

The researchers, therefore, measured multiple chemicals, such as the hydrocarbons propane, ethane, and butane, in the air, and from analyzing the types and ratios of gases present, they were able to use a mathematical technique to determine what sources had given rise to the gases and the accompanying methane. 

“We use that data to apportion the sources of methane in the L.A. area—as far as I know, that is the first time that has been done,” Peischl said.

The scientists found that more than 85 percent of the L.A. basin’s methane emissions comes from a combination of sources—leaks from pipeline-quality natural gas, geologic seeps (such as the La Brea tar pits), dairies, and landfills. In addition, they were able to identify that 8 percent of the methane emissions in the L.A. basin is due to leaks from the local oil and gas industry, which corresponds to a 17 percent leak rate for the Los Angeles–area oil and gas operations. This leak rate for the operations was similar to the findings of an independent study carried out by CARB.

Most importantly, however, the scientists were able to pin down what sources contributed to the discrepancy between the state’s estimates of methane emissions and the values measured in the atmosphere. “Methane leaks from pipeline-quality natural gas from urban-distribution systems and from geologic seeps, as well as emissions from the local oil and gas industry, account for inventory shortfalls in the Los Angeles area,” Peischl said.  The study was published May 14 in the Journal of Geophysical Research.

Would the scientists find these same sources of methane and discrepancies in other parts of the United States?

“We won’t know until we go there,” Peischl said. “But our technique now gives us a way to determine the sources of the methane in the atmosphere, whether from ground-based measurements or from aircraft.” 

CIRES coauthors on the study are J. Peischl, J. Brioude, K. C. Aikin, J. A. de Gouw, G. J. Frost, J. B. Gilman, J. S. Holloway, J. Kofler, and W. C. Kuster. Scientists from NOAA’s Earth System Research Laboratory, the University of Miami, the University of California, and Harvard University are also coauthors on the study.

Jeff Peischl, CIRES, 303-497-4849, 
Karin Vergoth, CIRES, 303-497-5125,

Download the photo

The cleanup of California’s tailpipe emissions over the last few decades has not only reduced ozone pollution in the Los Angeles area. It has also altered the pollution chemistry in the atmosphere, making the eye-stinging “organic nitrate” component of air pollution plummet, according to a new study led by a scientist from NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.

For the study, accepted last month for publication in the Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union, the scientists analyzed new data from research aircraft along with archived data going back a half-century to produce a comprehensive study of air pollution in the Los Angeles region.

“This is good news: LA’s air has lost a lot of its ‘sting,’” said lead author Ilana Pollack, a CIRES scientist who works at NOAA’s Earth System Research Laboratory in Boulder, Colo. “Our study shows exactly how that happened, and confirms that California’s policies to control emissions have worked as intended.”

Scientists have studied the origins and levels of air pollutants in the South Coast Air Basin – a region encompassing the Los Angeles urban area – for a long time. Since the 1960s, they have measured levels of ozone and other air pollutants that are formed in the atmosphere (so-called “secondary” pollutants) and the ingredients, or “precursors,” that form them: volatile organic compounds (VOCs) and nitrogen oxides (NOx). These precursors are directly emitted from various sources, primarily vehicle exhaust in LA but also from power-generating facilities, industry, and natural sources such as vegetation.

As studies began to identify the high levels of air pollution and its causes, policies and controls were implemented to restrict emissions of the NOx and VOC ingredients that result in ozone and other secondary air pollutants. Although the population in the Southern California region has tripled between 1960 and 2010, and the number of vehicles has increased by a similar factor, research studies have indicated that air pollution in the region has decreased—as a result of these policies.

To pin down the exact nature of the downward trends and the related changes in the chemistry causing the declining levels of pollutants, Pollack and her team examined new data from research aircraft and archived data from roadside monitors and ground-based instruments. In doing so, they generated a synthesis of information on ozone, other secondary pollutants and pollutant precursors from 1960 to 2010. This work included measurements of ozone and nitrogen oxides collected by Pollack and her colleagues over the South Coast Air Basin using instruments aboard NOAA’s P-3 research aircraft during a California-based mission in 2010.

The exhaustive approach paid off, and gave the scientists new insights into the changing chemistry of LA’s air.

“The emission reductions have ‘flipped’ some of the chemistry that takes place in the atmosphere,” said Pollack. “The relevant precursors in the atmosphere now favor chemical pathways that are more likely to produce nitric acid, and less likely to make ozone and peroxyacetyl nitrate (PAN).”

PAN is the organic nitrate compound historically associated with eye irritation (the “sting”) in Los Angeles smog.

“Compiling long-term trends in precursors and secondary products, then seeing all the data together on paper, really made changes in the chemistry stand out,” Pollack said.

The researchers’ analysis showed that emission control measures in Southern California have been effective.  Although emissions of precursors have declined, motor vehicles remain the dominant source of emissions in Los Angeles.

Understanding the past and present chemistry in the atmosphere that creates air pollution is critical to being able to estimate how much pollution will be formed in future years, Pollack said. “To most people the big deal is that things have got a lot better,” Pollack said.  “But as scientists we want to know how they have got better.”

The researchers hope that this new insight will provide useful information to the policy makers who will be crafting the next generation of policies aimed at improving air quality in the region.

“Our work aims to interpret the past and present observations, with an eye toward informing future decisions,” Pollack said.

CIRES scientist J.A. Neuman was a coauthor on the study. NOAA coauthors on the study were Thomas B. Ryerson, Michael Trainer, James M. Roberts and David D. Parrish. The authors work at the Chemical Sciences Division of NOAA’s Earth System Research Laboratory in Boulder, Colo. The Journal of Geophysical Research is a publication of the American Geophysical Union.

CIRES is a joint institute of the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado Boulder.

Media Contacts:
Ilana Pollack, CIRES scientist, 303-497-5826,
Karin Vergoth, CIRES, 303-497-5125,

Many photographs of the Southeast’s Smoky Mountains show layers of tall hills, shading to purples and grays in the distance. Tiny particles in the atmosphere help create the effect, which makes for stunning pictures. But human-caused enhancements of those fine particles also contribute to poor air quality in the Southeastern U.S., and may help explain why the region has not warmed like the rest of the nation.  

So this summer, scientists from the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado BoulderNOAA and colleagues from dozens of other institutions are taking one of the most detailed looks ever at the natural and manmade emissions that affect air quality in the Southeast, and their movement and chemical transformations within the atmosphere. The mission, called Southeast Nexus or SENEX, should help scientists determine the origin of the fine particles and how they contribute to the haziness in the region and affect regional air quality and temperature trends.  

Both the natural environment and human activities contribute to haziness in the Southeast. Plants and trees give off gases called volatile organic compounds (VOCs) that can react with manmade emissions in the atmosphere to create pollutants such as ozone and the tiny particles known as aerosols—the building blocks of haze. Power plants, refineries and other industrial sources also give off gases that lead to haze formation. The fine particles, known as aerosols, don’t simply diminish air quality and create visibility problems—they also affect the regional climate. Many aerosols reflect light coming directly from the sun and contribute to the formation of clouds that in turn reflect sunlight. In the Southeast, is the result a cooling influence, which has partially offset the warming effect of greenhouse gases?

“The Southeast has the highest natural emissions in the Nation, and also has high manmade emissions, humidity and cloudiness,” said CIRES atmospheric scientist Joost de Gouw. “The question is how all these ingredients combine and react to form a summertime haze that impacts air quality and may cool the climate.” De Gouw works at NOAA’s Earth System Research Laboratory in Boulder, Colo.

To investigate the complex processes in the atmosphere in the Southeast, CIRES, NOAA and other scientists are using a battalion of state-of-the art instruments that measure critical variables such as the types and concentrations of chemicals and aerosols, and the wind, temperature and moisture. One of NOAA’s WP-3D Orion research airplanes has been outfitted as a flying chemical laboratory for the mission and the aircraft and scientists will fly throughout the southeastern skies sampling air chemistry from Texas to the Atlantic Ocean and from the Ohio River Valley to the Gulf of Mexico.

"This mission may help crack key mysteries that have stumped air quality experts and climate scientists for decades. It's an impressive effort happening in the sky and on the ground that will bring valuable information to policy makers, scientists, and the public alike," said Steve Fine, Ph.D., deputy assistant administrator for NOAA Research.

The NOAA WP-3D is the main instrument platform for the SENEX study, which focuses on the interactions between natural and human-caused emissions at the nexus of climate change and air qualitySENEX, based out of Smyrna, Tenn., is conducted in close collaboration with colleagues from other agencies and academia under the umbrella of the Southeast Atmosphere Study (SAS). SAS is a six-week scientific investigation of the Southeast’s atmosphere, involving NOAA, the National Science Foundation, the Environmental Protection Agency, Electric Power Research Institute, and dozens of other domestic and international institutions. Taken together, the projects comprise the most detailed look ever at the natural and manmade emissions that affect air quality in the Southeast.

As part of the SAS study, three other aircraft—the NSF/NCAR C-130, the Purdue University Duchess and the Stonybrook University Long-EZ—will also be measuring the vital statistics of the atmosphere. SAS also includes key ground-based experiments, at Brent, Ala.; Birmingham, Ala., Look Rock, Tenn.; and Research Triangle Park, N.C. The instrumentation tower at Brent provides measurements of nearly 100 chemical species and aerosols from near the surface up to 20 meters above the ground.

“The last time an atmospheric study of this size took place in the Southeast was in the late 90s,” de Gouw said. “Since then, power plants and motor vehicles have become much cleaner, and it will be important to document how the atmosphere has responded to these changes.”

Media Contacts

Karin Vergoth, CIRES, , 303-497-5125
Katy Human, CIRES,, 303-735-0196
John Ewald, NOAA,, 240-429-6127

Scientist Contacts

Joost de Gouw, CIRES, 
Jessica Gilman, CIRES, 
Eric Williams,

On the web

The Southeast Atmosphere Study: 
Rutgers blog on the mission:

The Colorado River provides water for more than 30 million people in the U.S. West, so water managers have been eager to understand how climate change will affect the river’s flow. But scientific studies have produced an unsettling range of estimates, from a modest decrease of 6 percent by 2050 to a steep drop of 45 percent by then.

A new paper by researchers at the University of Washington (UW), CIRES, NOAA and other institutions across the West investigates and explains why those estimates differ and summarizes what is known about the future of this iconic Western river—key information for decision makers.

“We know, for example, that warmer temperatures will lead to more evaporation and less flow,” said co-author Bradley Udall, who contributed to the study as director of the CIRES Western Water Assessment, a NOAA-funded program at the University of Colorado Boulder. Udall is now director of CU Boulder’s Getches-Wilkinson Center for Natural Resources, Energy and Environment at Colorado Law. “Although projections of future precipitation aren’t as clear, it’s likely that we’re going to see a reduction in overall flow in the Colorado,” Udall said.

The study is published this week in the Bulletin of the American Meteorological Society.

While the paper does not narrow the existing range of estimates, it provides context for evaluating the current numbers. The 6 percent reduction estimate, for example, did not include some newer climate model runs, which tend to predict a drier West. And the 45 percent decrease estimate relied on models with a coarse spatial resolution that could not capture the effects of topography in the headwater regions. The new analysis, thus, supports more moderate estimates of changes in future flows.

“The different estimates have led to a lot of frustration,” said lead author Julie Vano, who recently earned a UW doctorate in civil and environmental engineering. “This paper puts all the studies in a single framework and identifies how they are connected.”

In evaluating recent scientific papers that estimate future flow of the Colorado River, she and her co-authors identified several reasons for different flow estimates. Among them are differences in:

  • Climate models and future-emissions scenarios used. Models run with higher future greenhouse gas emissions, for example, typically produce warmer and often drier climates, and smaller Colorado River flows.
  • The models’ spatial resolution, which is important for capturing topography and its effects on snow distribution in the Colorado River’s mountainous headwaters. Models with coarser resolution tend to overestimate the sensitivity of runoff to climate change.
  • Representation of land surface hydrology, which determines how precipitation and temperature changes will affect the land’s ability to absorb, evaporate or transport water.
  • Methods used to downscale from the roughly 200-kilometer resolution used by global climate models to the 10- to 20-kilometer resolution used by regional hydrology models.

The new paper also highlights several important realities faced by Western water managers reliant on Colorado River flows. The early 20th century, for example, is the basis for water allocation in the basin, but was a period of unusually high flow, so Colorado River water is already overallocated. Moreover, tree ring records suggest that the Colorado has experienced severe droughts in the past and will do so again, even without any human-caused climate change. If exacerbated by steadily decreasing flows due to climate change, such a “megadrought” could result in decades of extremely low streamflow, much lower than observed in the last century.


Paper authors include leaders in Western water issues, ranging from specialists in atmospheric sciences to hydrology to paleoclimate: Bradley Udall at CIRES’s Western Water Assessment and the University of Colorado Boulder; Daniel Cayan, Tapash Das and Hugo Hidalgo at the University of California, San Diego; Jonathan Overpeck, Holly Hartmann and Kiyomi Morino at the University of Arizona in Tucson; Levi Brekke at the U.S. Bureau of Reclamation; Gregory McCabe at the U.S. Geological Survey in Denver; Robert Webb and Martin Hoerling at the NOAA Earth System Research Laboratory in Boulder; and Kevin Werner at the National Weather Service in Salt Lake City.

The research was funded by NOAA through its Regional Integrated Sciences and Assessment program and its National Integrated Drought Information System.

For more information, contact lead author Julie Vano at 206-794-7946 or; Dennis Lettenmaier at 206-543-2532 or; or Bradley Udall at 303-492-1288 or

Hannah Hickey
University of Washington

Katy Human

The Council of Fellows and University of Colorado Boulder have selected Waleed Abdalati, Ph.D., as the new director of the Cooperative Institute for Research in Environmental Sciences (CIRES). Abdalati currently is a CIRES Fellow, professor in the Department of Geography at the University of Colorado Boulder and director of the CIRES Earth Science and Observation Center (ESOC). He will take office July 1, 2013.

“It is an honor to be selected as director of an organization full of such talented people doing such important work,” Abdalati said. “The depth and breadth of the outstanding scientists at CIRES and the societal importance of the research we do make CIRES a truly special place.”

Abdalati’s research focuses on using satellites and aircraft to understand how Earth’s ice cover, particularly glaciers and ice sheets, is changing and what those changes mean for life on the planet. He became ESOC director in 2008 and led the Ice Cloud and land Elevation Satellite-2 (ICESat-2) Science Definition Team, developing capabilities to map and understand changes in ice-sheet elevations by using space-based laser altimetry.

Abdalati earned a bachelor of science degree from Syracuse University in 1986; a master of science degree from the University of Colorado in 1991; and a Ph.D. from the University of Colorado in 1996, working with CIRES scientist Konrad Steffen. He went on to work as a scientist at NASA for 12 years before returning to CIRES.

“This appointment has special meaning for me because I earned my Ph.D. at CIRES 17 years ago, and back then, I never could have imagined serving as its director,” Abdalati said.

From January 2011 to December 2012, while on leave from the University of Colorado, Abdalati was NASA’s chief scientist, advising Administrator Charles Bolden on NASA science programs and strategic planning. He has published more than 60 scientific papers and technical reports; lectured to a wide range of audiences throughout the world, including scientists, policy makers, the media, and the general public; and received many notable honors and awards, including the NASA Exceptional Service Medal and, from the White House, the Presidential Early Career Award for Scientists and Engineers. Abdalati now brings that expertise to his new role as CIRES director.

“CIRES is a highly respected voice in the international environmental research community and, for nearly 50 years, has conducted cross-disciplinary science that helps NOAA carry out its mission to better monitor and understand our oceans and atmosphere,” said Robert Detrick, Ph.D., assistant administrator for NOAA’s Office of Oceanic and Atmospheric Research. “We congratulate Dr. Abdalati on his selection, and we look forward to working with him in his new position.”

Dr. William M. Lewis, Jr., has been at the helm of CIRES serving as interim director since the retirement of the previous CIRES director in the summer of 2012. CIRES has thrived under Dr. Lewis’s leadership, successfully adapting to the budget impacts of federal sequestration and securing the next five years of its core funding to support its collaborative work with NOAA, according to Stein Sture, vice chancellor for research at the University of Colorado Boulder.

“Bill’s efforts on behalf of CIRES, NOAA, and the university have strengthened CIRES and positioned the institute well for continued success in the coming decade,” Sture said.

“I am looking forward to helping CIRES fully realize that success,” Abdalati said.

Surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster, according to a new study by scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.

During the last decade, researchers have captured compelling evidence of accelerating ice flow at terminal regions, or “snouts,” of Greenland glaciers as they flow into the ocean along the western coast. Now, the new CIRES research shows that the interior regions are also flowing much faster than they were in the winter of 2000-2001, and the paper proposes a reason for the speedup.

“Through satellite observations, we determined that an inland region of the Sermeq Avannarleq Glacier, 40 to 60 miles from the coastis flowing about 1.5 times faster than it was about a decade ago,” said Thomas Phillips, lead author of the new paper and a CIRES research associate at the time of the study. In 2000-2001, the inland segment was flowing at about 130 feet (40 meters) per year; in 2007-2008, that speed was closer to 200 feet per year (60 m).

“At first, we couldn’t explain this rapid interior acceleration,” Phillips said. “We knew it wasn’t related to what was going on at the glacier’s terminus. The speedup had to be due to changes within the ice itself.”

To shed light on the observed acceleration, Phillips and his team developed a new model to investigate the effects of meltwater on the ice sheet’s physical properties. The team found that meltwater warms the ice sheet, which then—like a warm stick of butter—softens, deforms, and flows faster.

Previous studies estimated that it would take centuries to millennia for new climates to increase the temperature deep within ice sheets. But when the influence of meltwater is considered, warming can occur within decades and, thus, produce rapid accelerations. The paper has been accepted for publication in the Journal of Geophysical Research: Earth Surface, a journal of the American Geophysical Union.

The CIRES researchers were tipped off to this mechanism by the massive amount of meltwater they observed on the ice sheet’s surface during their summer field campaigns, and they wondered if it was affecting the ice sheet. During the last several decades, atmospheric warming above the Greenland Ice Sheet has caused an expanding area of the surface to melt during the summer, creating pools of water that gush down cracks in the ice. The meltwater eventually funnels to the interior and bed of the ice sheet.

As the meltwater drains through the ice, it carries with it heat from the sun.

“The sun melts ice into water at the surface, and that water then flows into the ice sheet carrying a tremendous amount of latent energy,” said William Colgan, a coauthor and CIRES adjunct research associate. “The latent energy then heats the ice.”

The new model shows that this speeds up ice flow in two major ways: One, the retained meltwater warms the bed of the ice sheet and preconditions it to accommodate a basal water layer, making it easier for the ice sheet to slide by lubrication. Two, warmer ice is also softer (less viscous), which makes it flow more readily.

“Basically, the gravitational force driving the ice sheet flow hasn’t changed over time, but with the ice sheet becoming warmer and softer, that same gravitational force now makes the ice flow faster,” Colgan said.

This transformation from stiff to soft only requires a little bit of extra heat from meltwater. “The model shows that a slight warming of the ice near the ice sheet bed—only a couple of degrees Celsius—is sufficient to explain the widespread acceleration,” Colgan said.

The findings have important ramifications for ice sheets and glaciers everywhere. “It could imply that ice sheets can discharge ice into the ocean far more rapidly than currently estimated,” Phillips said. “It also means that the glaciers are not finished accelerating and may continue to accelerate for a while. As the area experiencing melt expands inland, the acceleration may be observed farther inland.”

The new model will help scientists more accurately forecast these impacts, and it is being incorporated into Earth-system models for predicting future ice discharge from the Greenland Ice Sheet.

“Traditionally, latent energy has been considered a relatively unimportant factor, but most glaciers are now receiving far more meltwater than they used to and are increasing in temperature faster than previously imagined,” Colgan said. “The chunk of butter known as the Greenland Ice Sheet may be softening a lot faster than we previously thought possible.”

The study was funded through a NASA ROSES grant, NASA’s Greenland Climate Network, and the National Science Foundation. Other coauthors on the paper were CIRES Director Waleed Abdalati, former CIRES Director Konrad Steffen, and CU Boulder Engineering Professor Harihar Rajaram.

CIRES is a joint institute of the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado Boulder.

Katy Human, CIRES Communications Director, 303-735-0196,
Thomas Phillips, Thomas.Phillips@Colorado.EDU, +41 79 120 0858, Thomas.Phillips (Skype)
William Colgan,, +45 38 14 29 30

Information and graphics:
Download the images here: [ 1 ] [ 2 ]

Follow us on Facebook and Twitter: and @CIRESnews.


The natural biological resilience of freshwater species likely spared them from the otherwise devastating effects of the Chicxulub asteroid impact 66 million years ago, which had caused massive extinction in terrestrial and marine environments. 

When the Manhattan-sized asteroid slammed into Earth, it created an “impact winter,” a mass of dust and smoke in the atmosphere that blocked sunlight from reaching Earth’s sunlight for one or two years. The enduring lack of sunshine and cool temperatures meant a loss of phytoplankton, but CIRES scientist Douglas Robertson and his team propose that freshwater ecosystems proved more resilient to the sudden change. Freshwater species are often adapted to annual freeze-thaw cycles and would have held up better to the impact winter conditions. Fast-flowing streams could have reoxygenated inland waterways and organic matter could have been supplied by surface runoff. Furthermore, since many freshwater organisms have dormant stages they would have been able to wait out the inclement conditions imposed by the asteroid. 

The study was published online in July in the Journal of Geophysical Research Biogeosciences 

Douglas Robertson,, 303-682-2478

Media Contact: Kathleen Human,, 303-735-0196