Cooperative Institute for Research in Environmental Sciences

WASHINGTON—Black carbon is the second largest man-made contributor to global warming and its influence on climate has been greatly underestimated, according to the first quantitative and comprehensive analysis of this pollutant’s climate impact.

The direct influence of black carbon, or soot, on warming the climate could be about twice previous estimates, according to an in-depth study published today in the Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union. Accounting for all of the ways black carbon can affect climate, it is believed to have a warming effect of about 1.1 Watts per square meter (W/m2), approximately two-thirds of the effect of the largest man made contributor to global warming –  carbon dioxide.

“This study confirms and goes beyond other research that suggested black carbon has a strong warming effect on climate, just ahead of methane,” said co-lead author David Fahey, a NOAA research physicist who is also a Fellow with NOAA's Cooperative Institute for Research in Environmental Sciences (CIRES). The study, a four-year, 232-page effort, led by the International Global Atmospheric Chemistry (IGAC) Project, is likely to guide research efforts, climate modeling, and policy for years to come, the authors and other scientists familiar with the paper said..

The report’s best estimate of direct climate influence by black carbon is about a factor of two higher than most previous work. This includes the estimates in the 2007 Intergovernmental Panel on Climate Change (IPCC) Assessment, which were based on the best available evidence and analysis at that time.

Scientists have spent the years since the last IPCC assessment improving estimates, but the new assessment notes that emissions in some regions are probably higher than estimated. This is consistent with other research that also hinted at significant under-estimates in some regions’ black carbon emissions. 

The results indicate that there may be a greater potential to curb warming by reducing black carbon emissions than previously thought.

“There are exciting opportunities to cool climate by reducing soot emissions but it is not straightforward,” said co-author Professor Piers Forster from the University of Leeds’s School of Earth and Environment in the United Kingdom. “Reducing emissions from diesel engines and domestic wood and coal fires is a no-brainer, as there are tandem health and climate benefits. If we did everything we could to reduce these emissions we could buy ourselves up to half a degree (Celsius) less warming--or a couple of decades of respite.”.

However, the international team urges caution because the role of black carbon in climate change is complex. “Black carbon influences climate in many ways, both directly and indirectly, and all of these effects must be considered jointly,” says co-lead author Sarah Doherty of the University of Washington in Seattle, an expert in snow measurements.

The dark particles absorb incoming and scattered heat from the sun (called solar radiation), they can promote the formation of clouds that can have either cooling or warming impact, and they can fall on the surface of snow and ice, promoting warming and increasing melting. In addition, many sources of black carbon also emit other particles that provide a cooling effect, counteracting black carbon.

The research team quantified the complexities of black carbon and the impacts of co-emitted pollutants for different sources, taking into account uncertainties in measurements and calculations. The study suggests mitigation of black carbon emissions for climate benefits must consider all emissions from each source and their complex influences on climate.

Based on the scientists’ analyses of these different sources, black carbon emission reductions targeting diesel engines and some types of wood and coal burning in small household burners would have an immediate cooling impact.

Black carbon is a significant cause of the rapid warming in the Northern Hemisphere at mid to high latitudes, including the northern United States, Canada, northern Europe and northern Asia, according to the report. The particles’ impacts can also be felt farther south, inducing changes in rainfall patterns from the Asian Monsoon. Curbing black carbon emissions could therefore have significant impact on reducing regional climate change while having a positive impact on human health by reducing the amount of damage the particles cause to the respiratory and cardiovascular systems. 

“Policy makers, like the Climate and Clean Air Coalition, are talking about ways to slow global warming by reducing black carbon emissions,” said co-lead author Tami Bond of the University of Illinois at Urbana-Champaign. “This study shows that this is a viable option for some black carbon sources and since black carbon is short-lived, the impacts would be noticed immediately.  Mitigating black carbon is good for curbing short-term climate change, but to really solve the long-term climate problem, carbon dioxide emissions must also be reduced.”

A note from the editors of the Journal of Geophysical Research – Atmospheres, about  the significance of this article and the review process the article underwent, is available at

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this paper in press.

Or, you may order a copy of the final paper by emailing your request to Kate Ramsayer at Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release are under embargo.

“Bounding the role of black carbon in the climate system: A scientific assessment”

Authors (* indicates co-lead authors):
*Tami Bond
University of Illinois at Urbana-Champaign, USA;
*Sarah Doherty
Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, USA;
*David Fahey
NOAA Earth System Research Laboratory and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, USA.
*Piers Forster
University of Leeds, United Kingdom;

Contact information for the authors:
Tami Bond, Telephone: +1 (217) 244-5277, Email:
Sarah Doherty, Telephone: +1 (206) 543-6674, Email:
David Fahey, Telephone: +1 (303) 497-5277, Email:
Piers Forster, Email: (or contact Chris Bunting, Press Officer, +44 113 343 2049 or

NOAA announced seven multi-year awards totaling $600,000 to Regional Integrated Sciences and Assessments (RISA) research teams—including CIRES Western Water Assessment—to encourage collaboration with federal and non-federal partners on climate adaptation.

CIRES Fellow William Travis received $99,543 as part of the awards.

“NOAA's smaller awards focused on partnerships between RISA teams and other research and decision making institutions are a valuable mechanism for regional coordination," said Richard D. Rosen, acting director of NOAA’s Climate Program Office.

RISA, a program of the Climate Program Office within NOAA’s Office of Oceanic and Atmospheric Research, enables local-level interdisciplinary research needed to tackle big challenges such as impacts to water, food, infrastructure, and ecosystems. The program strengthens NOAA’s climate efforts by bringing academic and federal science and service communities together.

RISA teams are part of NOAA’s regional climate services partnerships, which include state climate offices and NOAA’s National Integrated Drought Information System, Regional Climate Service Directors, and Regional Climate Centers.  The seven new awards to RISA teams will help federal and non-federal partners better use climate information within their own structure.

Researchers have detected the presence of a pollutant-destroying compound—iodine monoxide (IO)—in surprisingly high levels high above the tropical ocean, according to a new study led by the Cooperative Institute for Research in Environmental Sciences (CIRES).

“The levels of IO we observed were much higher than expected,” said Rainer Volkamer, a CIRES Fellow and PI of the study. “The high concentrations in air that has not recently been in contact with the ocean surface point to the intriguing possibility of a recycling mechanism whereby instead of IO decaying away as previously thought, it’s released back to the atmosphere by heterogeneous chemistry on aerosol particles.”

IO is an important chemical because it destroys ozone, a greenhouse gas that warms the planet and also indirectly lowers methane levels, said Volkamer, also an assistant professor of chemistry and biochemistry. Additionally, IO can form aerosols—tiny particles suspended in the atmosphere that can initiate the production of clouds that can help cool the climate.

If IO is recycled in the atmosphere, as the research findings suggest, “It means IO has a longer effective lifetime and is, thus, much more broadly distributed, affects a much broader atmospheric air mass, and can destroy much more ozone,” Volkamer said.

The team’s analysis indicates that IO accounts for up to 20 percent of the overall ozone loss rate in the upper troposphere (the layer of the atmosphere extending from Earth’s surface up to about 60,000 feet). This ozone sink is currently missing in most atmospheric models.

The origin of IO is thought to be iodine emitted by microalgae or inorganic reactions at the ocean surface. Because IO occurs in relatively very small concentrations—one in 1013 molecules—it previously had been impossible to quantify the amount in the upper atmosphere.  

Volkamer’s team, however, solved that problem. They built an instrument— the University of Colorado Airborne Multi-Axis Differential Optical Absorption Spectroscopy (CU AMAX-DOAS) instrument—attached it to a research plane, and flew it over the tropical Pacific during January 2010, collecting and analyzing air samples from about 300 feet up to 33,000 feet to create a vertical profile of the atmosphere’s composition. The efforts marked the first aircraft measurements of IO, and the results appeared online Jan. 23 in the Proceedings of the National Academy of Sciences.

During the flight, the researchers studied both stable, aged air, which has had no contact with the ocean surface in days, and a deep convective storm, which pumps warm, moist air from the ocean surface into the upper troposphere.

Because IO has a very short lifetime in the atmosphere—it lasts only 30 to 60 minutes before forming aerosol particles—the researchers expected to find IO only near the ocean surface and in the storm cell, which acts like a “large vacuum cleaner, sucking air from the ocean surface up to 30,000 feet in as little as 20 minutes,” Volkamer said.

Instead, they discovered high levels of IO even in aged air that had not connected with the ocean for several days.

“Based on current understanding, iodine oxide shouldn’t be hanging around for more than one hour,” Volkamer said. “But these measurements reveal a surprising persistence of IO in air masses disconnected from the ground. We don’t see that the IO decays away. It still hangs around.”

The persistence of IO suggests that IO isn’t irreversibly lost to aerosol, Volkamer said. The aerosol “returns” the IO to the atmosphere. Such a recycling mechanism would be novel because iodine is a very heavy atom. “It’s like a cannonball,” Volkamer said. “It tends to form polymers and stick onto particles. But a portion seems to be returning into the gas phase.”

Such a recycling mechanism would extend the effective lifetime of IO, increasing the amount of ozone it destroys. The findings will help improve climate models’ predicative capability about how atmosphere behaves and how the atmosphere cleanses itself of pollutants and greenhouse gases, Volkamer said.

The next step will be to elucidate the mechanisms behind IO’s high concentrations.

“It’s exciting because the atmosphere has more cleansing mechanisms than we suspected,” Volkamer said.

Coauthors on the study include Barbara Dix, Sunil Baidar, James F. Bresch, Samuel R. Hall, K. Sebastian Schmidt, and Siyuan Wang. The research is funded by the US National Science Foundation. CIRES is a joint institute of the University of Colorado Boulder and NOAA.

Kristin Bjornsen, CIRES science writer, 303-492-1790,
Rainer Volkamer, CIRES Fellow, 303-492-1843,

Information and graphics
Download the photo.
For more information about Rainer Volkamer, go to

In the search for clues as to why Earth did not warm as much as scientists expected between 2000 and 2010, researchers have discovered the answer is hiding in plain sight. The study, led by a scientist from NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES), showed that dozens of volcanoes spewing sulfur dioxide have tempered the warming.

The findings essentially shift the focus away from Asia, including India and China, two countries that are estimated to have increased their industrial sulfur dioxide emissions by about 60 percent from 2000 to 2010 through coal burning, said lead author Ryan Neely, a CIRES scientist working at NOAA’s Earth System Research Laboratory. Small amounts of sulfur dioxide emissions from Earth’s surface eventually rise 12 to 20 miles into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulfuric acid and water particles that reflect sunlight back to space, cooling the planet.

Neely said previous observations suggest that increases in stratospheric aerosols since 2000 have counterbalanced as much as 25 percent of the warming scientists attribute to human greenhouse gas emissions. “This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet,” said Neely.

A paper on the subject was published online in Geophysical Research Letters, a publication of the American Geophysical Union. Co-authors include Professors Brian Toon and Jeffrey Thayer from CU Boulder; Susan Solomon, a former NOAA scientist now at the Massachusetts Institute of Technology; Jean Paul Vernier from NASA’s Langley Research Center in Hampton, Va.; Christine Alvarez, Karen Rosenlof and John Daniel from NOAA; and Jason English, Michael Mills and Charles Bardeen from the National Center for Atmospheric Research in Boulder.

The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, said Neely.  Since 2000, the optical depth in the stratospheric aerosol layer has increased by about 4 to 7 percent, meaning it is slightly more opaque now than in previous years.

“The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate,” said Toon of CU Boulder’s Department of Atmospheric and Oceanic Sciences. Overall these eruptions are not going to counter the human caused greenhouse warming, he said.  “Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.”

The key to the new results was the combined use of two sophisticated computer models, including the Whole Atmosphere Community Climate Model, or WACCM, Version 3, developed by NCAR and which is widely used around the world by scientists to study the atmosphere.  The team coupled WACCM with a second model, the Community Aerosol and Radiation Model for Atmosphere, or CARMA, which allows researchers to calculate properties of specific aerosols and which has been under development by a team led by Toon for the past several decades.

Neely said the team used the Janus supercomputer on (the CU) campus to conduct seven computer “runs,” each simulating 10 years of atmospheric activity tied to both coal-burning activities in Asia and to emissions by volcanoes around the world. Each run took about a week of computer time using 192 processors, allowing the team to separate coal-burning pollution in Asia from aerosol contributions from moderate, global volcanic eruptions. The project would have taken a single computer processor roughly 25 years to complete, said Neely.

The scientists said 10-year climate data sets like the one gathered for the new study are not long enough to determine climate change trends. “This paper addresses a question of immediate relevance to our understanding of the human impact on climate,” said Neely. “It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes.”

While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, said Toon. When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tons of sulfur dioxide into the atmosphere that cooled the Earth slightly for the next several years.

The research for the new study was funded in part through a NOAA/ ESRL-CIRES Graduate Fellowship to Neely.  The National Science Foundation and NASA also provided funding for the research project.  The Janus supercomputer is supported by NSF and CU Boulder and is a joint effort of CU Boulder, CU Denver and NCAR.

Ryan Neely, 336-302-4244

Brian Toon, 303-492-1534

Kate Ramsayer, AGU media relations, 202-777-7524

Jane Palmer, CIRES science writer, 303-492-6289

Why black carbon particles could be larger in snow

The scientists identified several mechanisms that could explain how the black carbon particles end up larger when they are in the snow, including smaller particles sticking together in the air; larger particles being more likely to be deposited in snow; and larger particles being formed in fallen snow that undergoes temperature fluctuations. However, they hypothesize that more complex interactions of the black carbon and snowflakes could be also be involved, likely as the snow is forming in the atmosphere. The size of the black carbon in snow contains a “fingerprint” of these interactions, providing hope that it can help improve scientists’ understanding of how the particles are removed from the air.

Black carbon particles—often referred to as “soot particles”— in snow are larger than expected, according to a new study led by scientists at NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES). Black carbon in snow contributes to climate warming and this finding suggests that the warming produced by black carbon in snow could be currently overestimated by as much as 30 percent.

 “For the first time, we looked at the size of these particles in snow, and found that they can be larger than in the air,” said lead author CIRES scientist Joshua Schwarz, who works at NOAA’s Earth System Research Laboratory. ”This is important for our understanding of how black carbon interacts with the atmosphere and how it can affect climate.”

Black carbon is a byproduct of combustion—both vehicle engines and cooking fires release these small dark particles into the air. Eventually the particles return to the ground in rain, snow, or by hitting the landscape.  Whereas white snow reflects most of the sun’s rays, darker soot-tainted snow will absorb more of the incoming radiation, changing the energy absorbed by the landscape and the rate at which the snow melts and exposes darker ground.

It is not just the net amount of black carbon in the snow that impacts the absorption of the sun’s rays, however—theory suggests the size of the particles should also play a role. Larger particles will absorb less radiation than the same weight of smaller particles. Previous models have assumed that the light absorption of black particles in the snow is approximately the same size as those particles in the atmosphere: an assumption, which if incorrect, could lead to errors in the warming estimates made by these models.

To measure the size of soot particles in the snow—previously unexplored territory—a team of CIRES, NOAA, and Science and Technology Corp. researchers, used an instrument known as the Single Particle Soot Photometer (SP2). The SP2, when installed on aircraft for research flights, can determine the size of black carbon particles in the atmosphere. To measure black carbon’s size in snow, however, the scientists developed a method to apply the SP2 to measuring black carbon’s size in liquid—in this instance, melted snow.

The team found the black carbon particles to be larger than those typically observed in the air and published the unexpected findings in the journal Nature Scientific Reports. “It surprised us even more once we calculated the possible change in the amount of light the larger particles would absorb,” Schwarz said. 

"These are important measurements and have the potential to alter how we represent black carbon-in-snow size distribution and optical properties, in global modeling efforts," Mark Flanner, of the Department of Atmospheric, Oceanic and Space Sciences at the University of Michigan. Flanner is one of 31 co-authors of a 4-year international study bounding the role of black carbon in climate. The study, published in January 2013 in the The Journal of Geophysical Research-Atmospheres concluded that black carbon exerts a substantially stronger warming effect on climate than quantified in the 2007 Intergovernmental Panel on Climate Change (IPCC) report.

The researchers based their findings on snow samples gathered in Colorado, but also saw indications of the large black carbon sizes in snow from remote Arctic regions. The tendency to form larger soot particles could be something that happens over large regions of the globe, Schwarz said. 

While the scientists note that the climate warming due to black carbon in snow could be currently underestimated, they add that further work is needed to refine the estimate of 30 percent. “This piece of the puzzle opens the door to many questions,” says Schwarz. “A next step is to pin down the implications for climate and understanding of black carbon removal from the air by snow.”

Joshua Schwarz, 303-497-4637,
Karin Vergoth, CIRES, 303-497-5125,

Graphics: Download the photos: [ 01 ] [ 02 ]

ICECAPS Information 

Playing key roles in the U.S. Arctic Observing Network (AON) and the International Arctic Systems for Observing the Atmosphere (IASOA) network, ICECAPS is a collaborative project between the universities of Colorado, Idaho, and Wisconsin, with substantial support from the National Science Foundation, the National Oceanic and Atmospheric Administration, the Department of Energy, and Environment Canada.

Principal Investigators Von Walden, Matthew Shupe, David Turner, and Ralf Bennartz lead a large team of field technicians, engineers, graduate students, and collaborators as they endeavor to make year-round measurements of the atmosphere and clouds in the extreme Greenland Ice Sheet environment

BAMS Article: Shupe, M. D., D. D. Turner, V. P. Walden, R. Bennartz, M. Cadeddu, B. Castellani, C. Cox, D. Hudak, M. Kulie, N. Miller, R. R. Neely III, W. Neff, and P. Rowe, 2013: High and Dry: New observations of tropospheric and cloud properties above the Greenland Ice Sheet. Bull. Amer. Meteor. Soc., 94, 169-186, doi:10.1175/BAMS-D-11-00249.1.

Scattering the skies above the Greenland Ice Sheet, seemingly innocent puffy, white clouds may be playing a key role in the region’s climate and ultimately the ice sheet’s destiny, according to a new study led by a scientist at NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES).

 “Clouds are a critical element of the climate system, especially in the Arctic where surface energy budgets and precipitation can have dramatic impacts on the fate of sea ice and ice sheets,” said CIRES scientist Matthew Shupe, who works at NOAA’s Earth System Research Laboratory.

High above the Greenland Ice Sheet, the presence of clouds bodes of warmer temperatures and higher winds. Like a cushy down comforter on a bed, clouds also alter the exchange of heat, or energy, between the atmosphere and ice surface and modify the stable near-surface atmospheric conditions.

Clouds impart two competing effects on the surface energy, Shupe said. They cool the surface by reflecting sunlight, but also warm the surface by trapping thermal radiation. The balance of these depends on the detailed properties of the clouds and surrounding atmosphere, he said.

Instrument innovation: The icing on the sheet

Concerned about the impacts of these cloudy skies, in 2010, a team of scientists initiated the first detailed project looking at cloud and atmosphere properties and processes over the Greenland Ice Sheet. The initial exciting results are rolling out, many of which are highlighted in the February issue of the Bulletin of the American Meteorological Society (BAMS). The innovative project earns a coveted front cover on the journal.

The Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) project based in Summit, Greenland, is a collaborative project among the universities of Colorado, Idaho, and Wisconsin. Perched atop the ice sheet, at 10,500 feet elevation and nearly 250 miles from the nearest town, the ICECAPS “office headquarters” is a laboratory to make any mad scientist proud.

Microwave and infrared radiometers, lidars, radars, ceilometers, sodars, and precipitation sensors squeezed into—or piled on top of—a building the size of a suburban garage provide a unique and unprecedented picture of the daily and seasonal variability of atmospheric structure, the clouds, their interactions with atmospheric radiation, and regional precipitation. The action recorded by this plethora of instrumentation can be followed via daily imagery available at

Surprisingly cloudy

The high-altitude and typically dry atmosphere at Summit wouldn’t suggest to the layperson an abundance of clouds. However, moist air masses periodically flow up over the ice sheet from warmer regions to the south. As the atmosphere cools, clouds comprised of liquid water can form, even at temperatures below the freezing point. These so-called “supercooled water” clouds are observed during all months of the year, even sometimes in the particularly cold and dry winter.

Also, when the air is extra cold, ice crystals, sometimes called “diamond dust,” form in the atmosphere, leading to outstanding optical displays.

 “The optics can be phenomenal! Halos around the sun, circles overhead, sundogs, columns, rainbow arches going in many directions,” Shupe said. “I’ve never seen such complex optical displays anywhere else. And the cool thing is that these displays actually tell us something about the ice crystal shapes that are present in the atmosphere.”

The ICECAPS observations indicate that the largest atmospheric moisture amounts, cloud water contents, and snowfall occur in summer and under southwesterly flow. Surprisingly, many of the basic structural properties of clouds observed at Summit, particularly in the low-level stratiform clouds, are very similar to their counterparts in other Arctic regions in spite of the unique environment encountered on top of the ice sheet, Shupe said.

"The fact that Greenlandic stratiform clouds that contain supercooled liquid water are similar to their cousins observed elsewhere in the Arctic offers insight into this important cloud type,” Shupe said. “As we study these clouds in many Arctic environments, we are finding that they have self-sustaining processes, which make them resilient and persistent under many conditions."

The ICECAPS observations and accompanying analyses will be used to improve the understanding of key cloud–atmosphere processes, Shupe said. Also, the findings will help develop and evaluate atmospheric models that have previously suffered from a dearth of data from this remote region.

Ultimately scientists rely on climate models to project the fate of the Greenland Ice Sheet and its potentially profound impacts on global sea level, Shupe said. But these models struggle to accurately represent clouds and their large contribution to the surface energy budget, he said.

“Our detailed observations and the research they support are critical for developing the understanding that is needed to properly simulate clouds and their interactions with the ice surface,” Shupe said.


Matthew Shupe, CIRES,, 303-497-6471
Karin Vergoth, CIRES,, 303-497-5125

The University of Colorado Foundation has announced the creation of the George C. Reid Endowed Scholarship Fund for the benefit of CIRES in the Graduate School at the University of Colorado Boulder. A generous gift from Joan Reid, George’s spouse, will fund the perpetual endowment. The scholarship will be awarded to support graduate students’ education, and financial need and merit may both be used as criteria in selection of recipients. This marks the first perpetual endowment CIRES has received through the CU Foundation.

George Colvin Reid (1929–2011) was an eminent atmospheric scientist who pioneered research into critical environmental issues such as stratospheric ozone depletion and global climate change. Always a progressive thinker, he was one of the initial four fellows who founded the Cooperative Institute for Research in Environmental Sciences in 1968.

Read a tribute to him here.

While scientists believe that water is necessary for the emergence of life on a planet, new findings suggest the water surface may play a more integral role, according to researchers at the Cooperative Institute for Research in Environmental Sciences (CIRES). These scientists have demonstrated that the interface between water and air provides a site for the formation of simple proteins called peptides, one of the key building blocks for life.

“We report unambiguous evidence of peptide-bond formation at the air-water interface, yielding insight into how complex proteins could have emerged on early Earth,” says lead author Elizabeth Griffith, a CIRES doctoral student. CIRES Fellow Veronica Vaida was principal investigator of the study, which appeared in the journal Proceedings of the National Academy of Sciences last fall. Their research is particularly timely because of recent findings by NASA’s Mars rover that habitable water once existed on the planet. 

Water-air interfaces are ubiquitous throughout nature, found at the surfaces of lakes, oceans, and atmospheric aerosols (small liquid or solid droplets suspended in air). Of these different surfaces, atmospheric aerosols that emanate from the ocean provide especially advantageous environments for this form of peptide chemistry and the “birth” of life. Collectively, the sea-born aerosols have a much larger surface area than all other water surfaces found on Earth combined and are constantly being generated by breaking waves sending up sea spray.

“The surfaces of these sea-born aerosols could be ‘pre-life reactors’ relevant to many planets,” Vaida said.

To investigate the phenomenon, the scientists observed the surface of a water solution by using very sensitive spectroscopy and other methods and found that the building blocks of peptides, amino acids, reacted—like box cars linking together to form a train—to create peptides at the water surface.

Until now, scientists had not been able to demonstrate how these peptides, which are critical for life, could form spontaneously in water under conditions that were realistic of early Earth. One reason such spontaneous peptide formation in water would be unfavorable has to do with the fact that when two of the building block amino acids join together, they release a water molecule.

“The release of a water molecule into water is highly unlikely—the reaction will not proceed in that direction,” Griffith said. “Thermodynamically, it’s like emptying a bag of marbles at the bottom of a steep hill and then expecting one of them to roll to the top unassisted.”

Additionally, the amino acids have to be oriented exactly with respect to one another and possess a precise charge state to form a peptide bond. These criteria rarely occur in bulk water, Griffith said.

The role of the water-air interface in this process, however, overcomes many of these hurdles. The interface positions the amino acids in the correct orientation and in the right form.

 “Water-air interfaces provide an auspicious environment for this type of chemistry through their provision of a water-scarce environment, alteration of the charge state of compounds on the surface, and ability to concentrate and align simple amino acids,” said Vaida.

The study sheds light on the enigma in modern biology of how cells manufacture complex proteins inside structures called ribosomes. It also offers a possible mechanism for how the first bio-polymers could have formed. These “life molecules” are essential for the emergence of organisms.

“This work gives insight into peptide formation en route to the emergence of more complex biomolecules on early Earth, and reinforces the importance of orientation, alignment, and proximity in the functioning of modern protein synthesis,” Vaida said.

The research is funded by a grant from the National Science Foundation, Chemistry Division and a NASA Earth and Space Science Graduate Fellowship. CIRES is a joint institute of the University of Colorado Boulder and NOAA.

Kristin Bjornsen, CIRES science writer, 303-492-1790,
Veronica Vaida, 303-492-8605,

Filmmaker and adventurer James Balog will share his stirring and beautiful glacial photography revealing changes in climate at a free event at 7 p.m., Monday, April 1 in the University of Colorado Boulder’s Macky Auditorium.

The event, “A Conversation with James Balog on the Art of Chasing Ice,” is hosted by Earth Vision Trust and CU Boulder’s Inside the Greenhouse, a multidimensional project that explores the nexus of environmental science and the arts and humanities.

Similarly, Balog and his work bridge art and science. Balog is the founder of the Extreme Ice Survey and the subject of the award-winning 2012 documentary film “Chasing Ice.” He is a Boulder-based photographer, but his work spans the globe documenting changing ecosystems through time-lapse photography stationed at 13 glaciers on four continents.

“I have spent my professional life exploring the intersection of humans and nature,” Balog said. “In ‘The Art of Chasing Ice,’ I am honored to present through words and images, the intrinsic beauty and fragility of ice, which motivated us to make the movie.

“As a graduate of CU, I am delighted to be collaborating with Inside the Greenhouse on debuting not only this artistic work but their new performance series,” he said.

During “The Art of Chasing Ice,” Balog will share his insights, images and never-seen-before footage while discussing his on-going work in a public interview with Beth Osnes, assistant professor of theatre and dance.  

Osnes leads Inside the Greenhouse in partnership with Max Boykoff, assistant professor in the Cooperative Institute for Research in Environmental Sciences (CIRES) and the Environmental Studies Program, and Rebecca Safran, assistant professor of ecology and evolutionary biology. All three professors work closely with Marda Kirn of EcoArts.

“Inside the Greenhouse was inspired by the Inside the Actors Studio model, but instead of probing the acting processes, we aim to draw out process, motivation and creative communications surrounding engagement with climate change,” Osnes said.

Inside the Greenhouse seeks to deepen the public understanding of how issues of climate change are communicated by creating artifacts— art, film, television programming— that convey climate change. The centerpiece of the project will feature highlights from the conversation with Balog and students’ creative work.

“Merely conveying information about climate change does not change behavior. We are interested in creative forms of communication that can bring out the relevance of the issues at the personal level,” Boykoff said. 

“We want to engage students and the public in conversations about climate change, but one of our primary goals was to bring a high-profile leader in climate issues to campus to inspire both students and the larger Boulder community.”

Safran added: “James Balog is the perfect artist to feature in this first project, because he is bringing the reality of climate change front and center through images that are impossible to ignore. By bringing us to parts of the world where climate change is most visible, we see undeniable proof that our world is changing—rapidly.”

Balog’s work began with a 2005 National Geographic assignment to photograph retreating glaciers, which inspired him to preserve the vivid, visual evidence of climate change. Currently the Extreme Ice Survey employs 28 time-lapse cameras running in the Rocky Mountains, Greenland, Iceland, Alaska, Glacier National Park and at Mount Everest to continually document the beauty of ice and the rapid retreat of the world’s glaciers.

For more information about “A Conversation with James Balog on the Art of Chasing Ice,” parking and other details visit Parking around Macky Auditorium is limited. Community members are encouraged to plan ahead. For more on the Inside the Greenhouse project visit

“The Art of Chasing Ice” is sponsored by the CU Boulder Institute of Arctic and Alpine Research (INSTAAR) and Learn More About Climate, an initiative that seeks to extend CU Boulder climate science expertise to educators, policymakers and citizens. Additional sponsors include CIRES, the National Snow and Ice Data Center, the CU Boulder Office for University Outreach, the CU Boulder Environmental Center and Flatirons Bank.

Max Boykoff,, 303-735-0451
Beth Osnes,, 303-492-0731
Rebecca Safran,, 303-735-1495
For interviews with James Balog contact Jane Saltzman,, 303-818-7785

Clouds over the central Greenland Ice Sheet last July were “just right” for driving surface temperatures there above the melting point, according to a new study by a team of scientists including a scientist at NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES). The study, published today in Nature, found that thin, low-lying clouds allowed the sun’s energy to pass through and warm the surface of the ice, while at the same time trapping heat near the surface of the ice cap. This combination played a significant role in last summer's record-breaking melt.

“Thicker cloud conditions would not have led to the same amount of surface warming,” said Matthew Shupe, research meteorologist with CIRES and the NOAA Earth System Research Laboratory. “To understand the region’s future, you’ll need to understand its clouds. Our finding has implications for the fate of ice throughout the Arctic.”

Scientists around the world are trying to understand how quickly Greenland is warming because ice melt there contributes to sea level rise globally. The Greenland Ice Sheet is second only to Antarctica in ice volume. In July, more than 97 percent of the Greenland Ice Sheet surface experienced some degree of melting, including at the National Science Foundation’s Summit Station, high atop the ice sheet. According to ice core records, the last time the surface at Summit experienced any degree of melting was in 1889, but it is not known whether this extended across the entire ice sheet.

To investigate whether clouds contributed to, or counteracted, the surface warming that melted the ice, the authors modeled the near-surface conditions. The model was based on observations from a suite of sophisticated atmospheric sensors operated as part of a study called the Integrated Characterization of Energy, Clouds, Atmospheric State and Precipitation at Summit (ICECAPS).

“The July 2012 ice melt was triggered by an influx of unusually warm air sweeping in from North America, but that was only one factor,” said David Turner, research meteorologist with the NOAA National Severe Storms Laboratory and one of the lead investigators. “In our paper, we show that low-lying clouds containing a low amount of condensed water were instrumental in pushing surface air temperatures up above freezing and causing the surface ice to melt.”

Clouds can cool the surface by reflecting solar energy back into space, and can warm it by radiating heat energy back down to the surface. The balance of those two processes depends on many factors, including wind speed, turbulence, humidity and cloud “thickness,” or liquid water content.

In certain conditions, these clouds can be thin enough to allow some solar radiation to pass through, while still “trapping” infrared radiation at ground level. That is exactly what happened last July: the clouds were just right for maximum surface warming. Thicker clouds would have reflected away more solar radiation; thinner ones couldn’t have trapped as much heat, and in either of those cases, there would have been less surface warming.

The researchers also found these thin, low-lying liquid clouds occur 30 to 50 percent of the time in summer, both over Greenland and across the Arctic. Current climate models tend to underestimate their occurrence in the Arctic, which limits those models’ ability to predict how clouds and their warming or cooling effects may respond to climate change.

“The cloud properties and atmospheric processes observed with the Summit Station instrument array provide a unique dataset to answer the large range of scientific questions we want to address,” said Turner. “Clouds play a big role in the surface mass and energy budgets over the Greenland Ice Sheet. Melting of the world’s major ice sheets can significantly impact human and environmental conditions via its contribution to sea-level rise.”

Better understanding of clouds also improves climate models.

“Our results may help to explain some of the difficulties that current global climate models have in simulating the Arctic surface energy budget, including the contributions of clouds,” said Ralf Bennartz, lead author for the study and professor at the University of Wisconsin-Madison. “Above all, this study highlights the importance of continuous and detailed ground-based observations over the Greenland Ice Sheet and elsewhere. Only such detailed observations will lead to a better understanding of the processes that drive Arctic climate.”


Matthew Shupe, CIRES,, 303-497-6471
Jane Palmer, CIRES science writer,, 303-492-6289
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