Climate News

February 12, 2013

Creeping climate change in the Southwest appears to be having a negative effect on pinyon pine reproduction, a finding with implications for wildlife species sharing the same woodland ecosystems, says a University of Colorado Boulder-led study.

The new study showed that pinyon pine seed cone production declined by an average of about 40 percent at nine study sites in New Mexico and northwestern Oklahoma over the past four decades, said CU-Boulder doctoral student Miranda Redmond, who led the study. The biggest declines in pinyon pine seed cone reproduction were at the higher elevation research sites experiencing more dramatic warming relative to lower elevations, said Redmond of CU’s ecology and evolutionary biology department.

“We are finding significant declines in pinyon pine cone production at many of our study sites,” said Redmond. “The biggest declines in cone production we measured were in areas with greater increases in temperatures over the past several decades during the March to October growing season.”

Temperature and precipitation were recorded at official long-term weather stations located near each of the nine sites. Overall, average temperatures in the study areas have increased by about 2.3 degrees Fahrenheit in the past four decades, she said.

A paper on the subject by Redmond, Assistant Professor Nichole Barger of CU-Boulder and Frank Forcella of the United States Department of Agriculture in Morris, Minn., appeared in a recent issue of the journal Ecosphere, published by the Ecological Society of America. The new study was funded primarily by a National Science Foundation Graduate Research Fellowship to Redmond.

The cones in which the pinyon seeds are produced are initiated two years prior to seed maturity, and research suggests the environmental stimulus for cone initiation is unseasonably low temperatures during the late summer, said Redmond. Between 1969 and 2009, unseasonably low temperatures in late summer decreased in the study areas, likely inhibiting cone initiation and development.

The study is one of the first to examine the impact of climate change on tree species like pinyon pines that, instead of reproducing annually, shed vast quantities of cones every few years during synchronous, episodic occurrences known as “masting” events. Redmond said such masting in the pinyon pine appears to occur every three to seven years, resulting in massive “bumper crops” of cones covering the ground.

In the new Ecosphere study, the researchers compared two 10-year sequences of time. In addition to showing that total pinyon pine cone production during the 2003-2012 decade had declined from the 1969-1978 decade in the study areas, the team found the production of cones during masting events also declined during that period.

Some scientists believe masting events evolved to produce a big surplus of nut-carrying cones -- far too many for wildlife species to consume in a season -- making it more likely the nuts eventually will sprout into pinyon pine seedlings, she said. Others have suggested masting events occur during favorable climate conditions and/or to increase pollination efficiency. “Right now we really don’t know what drives them,” Redmond said.

“Across a range of forested ecosystems we are observing widespread mortality events due to stressors such as changing climate, drought, insects and fire,” said CU’s Barger.  “This study provides evidence that increasing air temperatures may be influencing the ability of a common and iconic western U.S. tree, pinyon pine, to reproduce. We would predict that declines in pinyon pine cone production may impact the long-term viability of these tree populations.”

Wildlife biologists say pinyon-juniper woodlands are popular with scores of bird and mammal species ranging from black-chinned hummingbirds to black bears. A 2007 study by researchers at the University of Northern Arizona estimated that 150 Clark’s Nutcrackers cached roughly 5 million pinyon pine nuts in a single season, benefiting not only the birds themselves but also the pines whose nuts were distributed more widely for possible germination.

For the new study, Redmond revisited nine pinyon pine study sites scattered throughout New Mexico and Oklahoma that had been studied previously in 1978 by Forcella. Both Forcella and Redmond were able to document pinyon pine masting years by counting small, concave blemishes known as “abscission scars” on individual tree branches that appeared after the cones have been dropped, she said.

Since each year in the life of a pinyon pine tree is marked by a “whorl” -- a single circle of branches extending around a tree trunk -- the researchers were able to bracket pinyon pine reproductive activity in the nine study areas for the 1969-1978 decade and 2003-2012 decade, which were then compared.

Pinyon pines take three growing seasons, or about 26 months, to produce mature cones from the time of cone initiation.  Low elevation conifers including pinyon pines grow in water-limited environments and have been shown to have higher cone output during cool and/or wet summers, said Redmond. In addition to the climate-warming trend under way in the Southwest, the 2002-03 drought caused significant mortality in pinyon pine forests, Redmond said.

“Miranda’s ideas and accompanying results will be of value to ecologists and land managers in the deserts of the Southwest and beyond,” said Forcella, now a research agronomist in the USDA’s Agricultural Research Service.  “The work is evidence that the University of Colorado continues to cultivate a cadre of high-caliber graduate students for which it rightfully can take tremendous pride.”

Pinyon nuts, the Southwest’s only commercial source of edible pine seeds today, were dietary staples of indigenous Americans going back millennia.

For more information on CU-Boulder’s ecology and evolutionary biology department visit http://ebio.colorado.edu.

Contact:


Miranda Redmond, 415-300-6901


Mirandaredmond@gmail.com


Nichole Barger, 303-492-8239


Nichole.Barger@colorado.edu

January 24, 2013
CIRES news release

Researchers have detected the presence of a pollutant-destroying compound iodine monoxide in surprisingly high levels high above the tropical ocean, according to a new study led by the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences.

“The levels of IO we observed were much higher than expected,” said Rainer Volkamer, a CIRES fellow and principal investigator 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.

Co-authors 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 U.S. National Science Foundation. CIRES is a joint institute of CU-Boulder and NOAA.

Contact:

Kristin Bjornsen, CIRES science writer, 303-492-1790

Kristin.Bjornsen@colorado.edu


Rainer Volkamer, CIRES Fellow, 303-492-1843


Rainer.Volkamer@colorado.edu
 

January 23, 2013

A new study by an international team of scientists analyzing ice cores from the Greenland ice sheet going back in time more than 100,000 years indicates the last interglacial period may be a good analog for where the planet is headed in terms of increasing greenhouse gases and rising temperatures.



The new results from the NEEM deep ice core drilling project led by the University of Copenhagen and involving the University of Colorado Boulder show that between 130,000 and 115,000 years ago during the Eemian interglacial period, the climate in north Greenland rose to about 14 degrees Fahrenheit warmer than today. Despite the strong warming signal during the Eemian -- a period when the seas were roughly 15 to 25 feet higher than today -- the surface of the north Greenland ice sheet near the NEEM facility was only a few hundred yards lower than it is today, an indication to scientists it contributed less than half of the total sea rise at the time.



The NEEM project involves 300 scientists and students from 14 countries and is led by Professor Dorthe Dahl-Jensen, director of the University of Copenhagen’s Centre of Ice and Climate.  CU-Boulder geological sciences professor and ice core expert Jim White is the lead U.S. investigator on the project.  The National Science Foundation’s Division of Polar Programs funded the U.S. portion of the effort.



The new Nature findings showed that about 128,000 years ago, the surface elevation of ice near the NEEM site was more than 650 feet higher than present but the ice was starting to thin by about 2 inches per year.  Between about 122,000 and 115,000 years ago, Greenland’s surface elevation remained stable at roughly 425 feet below the present level.  Calculations indicate Greenland’s ice sheet volume was reduced by no more than 25 percent between 128,000 years ago and 122,000 years ago, said White.



A paper on the subject was published in the Jan. 24 issue of Nature.



“When we calculated how much ice melt from Greenland was contributing to global sea rise in the Eemian, we knew a large part of the sea rise back then must have come from Antarctica,” said White, director of CU-Boulder’s Institute of Arctic and Alpine Research. “A lot of us had been leaning in that direction for some time, but we now have evidence that confirms that the West Antarctic ice sheet was a dynamic and crucial player in global sea rise during the last interglacial period.”



Dahl-Jensen said the loss of ice mass on the Greenland ice sheet in the early part of the Eemian was likely similar to changes seen there by climate scientists in the past 10 years. Other studies have shown the temperatures above Greenland have been rising five times faster than the average global temperatures in recent years, and that Greenland has been losing more than 200 million tons of ice annually since 2003. The Greenland ice loss study was led by former CU-Boulder scientist Isabella Velicogna, who is currently a faculty member at the University of California, Irvine.



The intense melt in the vicinity of NEEM during the warm Eemian period was seen in the ice cores as layers of re-frozen meltwater.  Such melt events during the last glacial period were rare by comparison, showing that the surface temperatures at the NEEM site were in a cold, nearly constant state back then. But on July 12, 2012, satellite images from NASA indicated 97 percent of Greenland’s ice sheet surface had thawed as a result of warming temperatures.



"We were quite shocked by the warm surface temperatures observed at the NEEM ice camp in July 2012,” said Dahl-Jensen. “It was raining at the top of the Greenland ice sheet, and just as during the Eemian period, meltwater formed subsurface ice layers. While this was an extreme event, the present warming over Greenland makes surface melt more likely, and the predicted warming over Greenland in the next 50-100 years will very likely be so strong that we will potentially have Eemian-like climate conditions.”



The Greenland ice core layers -- formed over millennia by compressed snow -- are being studied in detail using a suite of measurements, including stable water isotope analysis that reveals information about temperature and greenhouse gas levels and moisture changes back in time. Lasers are used to measure the water stable isotopes and atmospheric gas bubbles trapped in the ice cores to better understand past variations in climate on an annual basis -- similar in some ways to a tree-ring record.



The results from the Nature study provide scientists with a “road map” of sorts to show where a warming Earth is headed in the future, said White.  Of the nine hottest years on Earth on record, eight have come since the year 2000.  In 2007 the Intergovernmental Panel on Climate Change concluded that temperatures on Earth could climb by as much as 11 degrees F by 2100.



Increasing amounts of carbon dioxide in the atmosphere from sources like vehicle exhaust and industrial pollution -- which have risen from about 280 parts per million at the onset of the Industrial Revolution to 391 parts per million today -- are helping to raise temperatures on Earth, with no end in sight, said White.



"Unfortunately, we have reached a point where there is so much carbon dioxide in the atmosphere it’s going to be difficult for us to further limit our impact on the planet,” White said.  “Our kids and grandkids are definitely going to look back and shake their heads at the inaction of this country’s generation. We are burning the lion’s share of oil and natural gas to benefit our lifestyle, and punting the responsibility for it.”



In the past, Earth’s journey into and out of glacial periods is thought to be due in large part to variations in its orbit, tilt and rotation that change the amount of solar energy delivered to the planet, he said. But the anthropogenic warming on Earth today could override such episodic changes, perhaps even staving off an ice age, White said.



While three previous ice cores drilled in Greenland in the last 20 years recovered ice from the Eemian, the deepest layers were compressed and folded, making the data difficult to interpret.  Although there was some folding of the lowest ice layers in the NEEM core, sophisticated ice-penetrating radar helped scientists sort out and interpret the individual layers to paint an accurate picture of the warming of Earth’s Northern Hemisphere as it emerged from the previous ice age, White said.



In addition to White, other CU-Boulder co-authors on the NEEM paper include INSTAAR scientist Bruce Vaughn and graduate student Tyler Jones of INSTAAR and CU-Boulder’s Environmental Studies Program.



“It’s a challenge being on the ice sheet, because we are out of our comfort zones and are working long, physical hours in an environment that is extremely cold and where the sun never sets,” Jones said.  “Being a member of the research team allowed me to understand the ice core recovery process and the science behind it in terms of learning more about past climates and the implications for future climate change.”



Other nations involved in NEEM include Belgium, Canada, France, Germany, Iceland, Japan, Korea, the Netherlands, Sweden, Switzerland and the United Kingdom. Other U.S. institutions involved in the effort include Oregon State University, Penn State, the University of California, San Diego and Dartmouth College.



For more information on INSTAAR go to http://instaar.colorado.edu/. Additional information, photos and videos on NEEM can be found at http://www.neem.ku.dk.


Contacts
Dorthe Dahl-Jensen, 011-45 22 894 537


ddj@gfy.ku.dk


Jim White, 303-492-7909


James.White@colorado.edu

A team of researchers involving CU-Boulder is exhuming ice cores from Greenland, shown here, to better understand the past interglacial period known as the Eemian.  Photo courtesy Tyler Jones, University of Colorado

January 16, 2013

A new NASA-led study involving the University of Colorado Boulder finds that when it comes to combating global warming caused by emissions of ozone-forming chemicals, location matters.    

Ozone is both a major air pollutant with known adverse health effects and a greenhouse gas that traps heat from escaping Earth’s atmosphere. Scientists and policy analysts are interested in learning how curbing the emissions of ozone-forming chemicals can improve human health and also help mitigate climate change.

Research scientists Kevin Bowman of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and Daven Henze, assistant professor of mechanical engineering at CU-Boulder, set out to quantify, down to areas the size of large metropolitan regions, how the climate-altering impacts of these chemical emissions vary around the world. The chemicals, which are produced from sources such as planes, factories and automobiles, are converted to ozone in the presence of sunlight and subsequently transported by wind around our planet. Among these chemicals are nitrogen dioxide, carbon monoxide and non-methane hydrocarbons.

By combining satellite observations of how much heat ozone absorbs in Earth’s atmosphere with a model of how chemicals are transported in the atmosphere, the researchers discovered significant regional variability — in some places by more than a factor of 10 — in how efficiently ozone trapped heat in Earth’s atmosphere, depending upon where the ozone-forming chemical emissions were located. This variability was found within individual continents and even among different regions with similar emission levels within individual countries.

High-latitude regions such as Europe had a smaller impact than lower-latitude regions like North America. Ozone was observed to be a more efficient greenhouse gas over hot regions like the tropics or relatively cloud-free regions like the Middle East. The satellite data were collected by the Tropospheric Emission Spectrometer instrument on NASA’s Aura spacecraft.

“When it comes to reducing ozone levels, emission reductions in one part of the world may drive greenhouse warming more than a similar level of emission reductions elsewhere,” said Bowman, lead author of the study, published recently in the journal Geophysical Research Letters. “Where you clean up ozone precursor emissions makes a big difference. It’s all about — to use a real estate analogy — location, location, location.”

Variations in chemicals that lead to the production of ozone are driven by industry and human population. For example, the U.S. Northeast has much higher ozone precursor emission levels than, say, Wisconsin.

“We show that, for example, emissions of nitrogen dioxide in Denver are 20 percent more effective in contributing to ozone’s greenhouse gas effect than emissions of nitrogen dioxide in the San Francisco Bay area, even though both are at similar latitudes ” Bowman added. “Denver is at a much higher altitude than San Francisco and therefore can export ozone efficiently into the upper atmosphere where it is a more effective greenhouse gas.”

The researchers found that the top 15 regional contributors to global ozone greenhouse gas levels were predominantly located in China and the United States, including the regions that encompass New Orleans, Atlanta and Houston.

Bowman and Henze found considerable variability in how different types of emissions contribute to ozone’s greenhouse gas effect. For example, compared to all nitrogen dioxide emissions — both human-produced and natural — industrial and transportation sources make up a quarter of the total greenhouse gas effect, whereas airplanes make up only 1 percent.  They also found that nitrogen dioxide contributes about two-thirds of the ozone greenhouse gas effect compared with carbon monoxide and non-methane hydrocarbons.

Bowman said the research suggests that solutions to improve air quality and combat climate change should be tailored for the regions in which they are to be executed.

“One question that’s getting a lot of interest in policy initiatives such as the United Nations’ Environment Programme Climate and Clean Air Coalition is controlling short-lived greenhouse gases like methane and ozone as part of a short-term strategy for mitigating climate change,” Bowman said. “Our study could enable policy researchers to calculate the relative health and climate benefits of air pollution control and pinpoint where emission reductions will have the greatest impacts. This wasn’t really possible to do at these scales before now. This is particularly important in developing countries like China, where severe air pollution problems are of greater concern to public officials than climate change mitigation in the short term.”

“Our study is an important step forward in this field because we’ve built a special model capable of looking at the effects of location at a very high resolution,” said Henze. “The model simulations are based upon actual observations of ozone warming effects measured by NASA’s Tropospheric Emission Spectrometer satellite instrument. This is the first time we’ve been able to separate observed heat trapping due to ozone into its natural versus human sources, and even into specific types of human sources, such as fossil fuels versus biofuels. This information can be used to mitigate climate change while improving air quality.”

For more information on the Tropospheric Emission Spectrometer visit http://tes.jpl.nasa.gov.

Contact:
Daven Henze, 303-492-8716


Daven.Henze@colorado.edu


Alan Buis, NASA media relations, 818-354-0474


Alan.Buis@jpl.nasa.gov
 

January 14, 2013

A research team involving several scientists from the University of Colorado Boulder has found an unexpected silver lining in the devastating pine beetle outbreaks ravaging the West: Such events do not harm water quality in adjacent streams as scientists had previously believed.

According to CU-Boulder team member Professor William Lewis, the new study shows that smaller trees and other vegetation that survive pine beetle invasions along waterways increase their uptake of nitrate, a common disturbance-related pollutant. While logging or damaging storms can drive stream nitrate concentrations up by 400 percent for multiple years, the team found no significant increase in the nitrate concentrations following extensive pine beetle tree mortality in a number of Colorado study areas.

“We found that the beetles do not disturb watersheds in the same way as logging and severe storms,” said Lewis, interim director of CU’s Cooperative Institute for Research in Environmental Sciences. “They leave behind smaller trees and other understory vegetation, which compensate for the loss of larger pine trees by taking up additional nitrate from the system. Beetle-kill conditions are a good benchmark for the protection of sub-canopy vegetation to preserve water quality during forest management activities.”

A paper on the subject was published in the Jan. 14 issue of the Proceedings of the National Academy of Sciences.

“The U.S. Forest Service and other agencies have established harvesting practices that greatly mitigate damage to forests caused by logging, and they deserve credit for that,” said Lewis. “But this study shows just how important the survival of smaller trees and understory vegetation can be to stream water quality.”

In waterways adjacent to healthy pine forests, concentrations of nitrate is generally far lower than in rivers on the plains in the West like the South Platte, said Lewis. Nitrate pollution is caused by agricultural runoff from populated areas and by permitted discharges of treated effluent from water treatment facilities.

“In Colorado, many watersheds have lost 80 to 90 percent of their tree canopy as a result of the beetle epidemic,” said Lewis, also a faculty member in CU-Boulder’s ecology and evolutionary biology department.  “We began to wonder whether the loss of the trees was reducing water quality in the streams. We knew that forestry and water managers were expecting big changes in water quality as a result of the pine beetle outbreak, so we decided to pool our university and federal agency resources in order to come up with an answer.”

Study co-author and CU-Boulder Research Associate James McCutchan of CIRES said the new results should help forest managers develop more effective ways to harvest timber while having the smallest effect possible on downstream ecosystems.  “This study shows that at least in some areas, it is possible to remove a large part of the tree biomass from a watershed with a very minimal effect on the stream ecosystem,” he said.

Understory vegetation left intact after beetle outbreaks gains an ecological advantage in terms of survival and growth, since small trees no longer have to compete with large trees and have more access to light, water and nutrients, said McCutchan. Research by study co-author and former CU undergraduate Rachel Ertz showed concentrations of nitrate in the needles of small pines that survived beetle infestations were higher than those in healthy trees outside beetle-killed areas, another indication of how understory vegetation compensates for environmental conditions in beetle kill areas.

The researchers used computer modeling to show that in western forests, such a  “compensatory response” provides potent water quality protection against the adverse effects of nitrates only if roughly half of the vegetation survives “overstory” mortality from beetle kill events, which is what occurs normally in such areas, said Lewis.

Other study co-authors included Leigh Cooper, Thomas Detmer and Thomas Veblen from CU-Boulder, John Stednick from Colorado State University, Charles Rhoades from the U.S. Forest Service, Jennifer Briggs and David Clow from the U.S. Geological Survey and Gene Likens of the Cary Institute of Ecosystem Studies in Millbrook, N.Y.

The severe pine beetle epidemic in Colorado and Wyoming forests is part of an unprecedented beetle outbreak that ranges from Mexico to Canada. A November 2012 study by CU-Boulder doctoral student Teresa Chapman showed the 2001-02 drought greatly accelerated the development of the mountain pine beetle epidemic.

The researchers measured stream nitrate concentrations at more than 100 sites in western Colorado containing lodgepole pines with a range of beetle-induced tree damage.  The study area included measurements from the Fraser Experimental Forest near Granby, Colo., a 23,000-acre study area established by the USFS in 1937.

The new study was funded by the USFS, the USGS, the National Science Foundation, the National Oceanic and Atmospheric Administration and the National Park Service.  CIRES is a joint research institute between CU-Boulder and NOAA.

Contact:


William Lewis, 303-492-6378


lewis@spot.colorado.edu


James McCutchan, 303-492-5192


James.McCutchan@colorado.edu
 

December 7, 2012

Gaping crevasses that penetrate upward from the bottom of the largest remaining ice shelf on the Antarctic Peninsula make it more susceptible to collapse, according to University of Colorado Boulder researchers who spent the last four Southern Hemisphere summers studying the massive floating sheet of ice that covers an area twice the size of Massachusetts.

But the scientists also found that ribbons running through the Larsen C Ice Shelf – made up of a mixture of ice types that, together, are more prone to bending than breaking – make the shelf more resilient than it otherwise would be.

The research team from CU-Boulder’s Cooperative Institute for Research in the Environmental Sciences presented the findings Dec. 6 at the American Geophysical Union’s annual meeting in San Francisco.

The Larsen C Ice Shelf is all that’s left of a series of ice shelves that once clung to the eastern edge of the Antarctic Peninsula and stretched into the Weddell Sea. When the other shelves disintegrated abruptly – including Larsen A in January 1995 and Larsen B in February 2002 – scientists were surprised by the speed of the breakup.

Researchers now believe that the catastrophic collapses of Larsen A and B were caused, at least in part, by rising temperatures in the region, where warming is increasing at six times the global average. The Antarctic Peninsula warmed 4.5 degrees Fahrenheit since the middle of the last century.

The warmer climate increased meltwater production, allowing more liquid to pool on top of the ice shelves. The water then drained into surface crevasses, wedging them open and cracking the shelf into individual icebergs, which resulted in rapid disintegration.

But while the meltwater may have been responsible for dealing the final blow to the shelves, researchers did not have the opportunity to study how the structure of the Larsen A and B shelves may have made them more vulnerable to drastic breakups – or protected the shelves from an even earlier demise.

CU-Boulder researchers did not want to miss the same opportunity on the Larsen C shelf, which covers more than 22,000 square miles of sea.

“It’s the perfect natural laboratory,” said Daniel McGrath, a doctoral student in the Department of Geography and part of the CIRES research team. “We wanted to study this shelf while it’s still stable in order to get a better understanding of the processes that affect ice shelf stability.”

McGrath worked with CIRES colleagues over the last four years to study the Larsen C shelf in order to better understand how the warming climate may have interacted with the shelf’s existing structure to increase its vulnerability to a catastrophic collapse.

McGrath presented two of the group’s key findings at the AGU meeting. The first was the role that long-existing crevasses that start at the base of the shelf and propagate upward – known as basal crevasses – play in making the shelf more vulnerable to disintegration. The second relates to the way a type of ice found in areas called suture zones may be protecting the shelf against a breakup.

The scientists used ground penetrating radar to map out the basal crevasses, which turn out to be massive. The yawning cracks can run for several miles in length and can penetrate upwards for more than 750 feet. While the basal crevasses have been a part of Larsen C for hundreds of years, the interaction between these features and a warming climate will likely make the shelf more susceptible to future disintegration. “They likely play a really important role in ice-shelf disintegration, both past and future,” McGrath said.

The research team also studied the impact of suture zones in the ice shelf. Larsen C is fed by 12 distinct glaciers, which dump a steady flow of thick ice into the shelf. But the promontories of land between the glacial outlets, where ice does not flow into the shelf, allow for the creation of ribbon-like suture zones, which knit the glacial inflows together and which turn out to be important to the ice shelf’s resilience. “The ice in these zones really holds the neighboring inflows together,” McGrath said.

The suture zones get their malleable characteristic from a combination of ice types. A key component of the suture zone mixture is formed when the bottoms of the 12 glacial inflows begin to melt. The resulting freshwater is more buoyant than the surrounding seawater, so it rises upward to the relatively thinner ice zones between the glacial inflows, where it refreezes on the underside of the shelf and contributes to the chaotic ice structure that makes suture zones more flexible than the surrounding ice.

It turns out that the resilient characteristics of the suture zones keep cracks, including the basal crevasses, from spreading across the ice shelf, even where the suture zone ice makes up a comparatively small amount of the total thickness of the shelf. The CIRES team found that at the shelf front, where the ice meets the open sea, suture zone ice constitutes only 20 percent of the total thickness of the shelf but was still able to limit the spread of rifts through the ice. “It’s a pretty small part of the total ice thickness, and yet, it still has this really important role of holding the ice shelf together,” McGrath said.

Other CU researchers involved in the Larsen C project were Konrad Steffen, former director of CIRES; Ted Scambos, of CIRES and CU-Boulder’s National Snow and Ice Data Center; Harihar Rajaram, of the Department of Civil Engineering; and Waleed Abdalati, of CIRES.

CIRES is a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration.

Contact:


Dan McGrath


Daniel.McGrath@colorado.edu

 

Dec 4, 2012

A team led by the University of Colorado Boulder has been awarded $9.2 million over five years from the U.S. Department of Energy to research modifying E. coli to produce biofuels such as gasoline.

“This is a fantastic opportunity to take what we have worked on for the past decade to the next level,” said team leader Ryan Gill, a fellow of CU-Boulder’s Renewable and Sustainable Energy Institute, or RASEI. “In this project, we will develop technologies that are orders of magnitude beyond where we are currently.”

The team is working with a non-pathogenic strain of E. coli. Among the microbe’s more than 4,000 genes, the team is searching for a small set and how it can be manipulated in a combination of on and off states to change the bacteria’s behavior.

“E. coli is not going to want to make your biofuel at all,” said Gill, who’s also a CU-Boulder associate professor of chemical and biological engineering. “It doesn’t do that naturally. It’s programmed with thousands of genes controlling how it replicates. We’re figuring out what control structure we need to rewire in the bug to make it do what we want, not what it wants.”

Included in the team are Rob Knight, CU-Boulder associate professor of chemistry and biochemistry; Pin-Ching Maness, principal scientist at DOE’s National Renewable Energy Laboratory, or NREL; and Adam Arkin, physical biosciences director at DOE’s Lawrence Berkeley National Laboratory.

The researchers hope to engineer the production of ethylene and isobutanol in the modified E. coli. The two compounds are widely used commodities that can be converted into gasoline among other chemicals.

The greatest challenge is harnessing an efficient and inexpensive process that competes with abundant and low-cost fossil fuels like oil, according to Gill.

“Microorganisms and their genomes are incredibly complex machines,” said Gill. “The first step alone -- of pinpointing the part of the E. coli genome that can help us make biofuels or other chemicals on a cost-competitive basis -- is a daunting challenge. Then we have to determine if the results we want will take one year or decades, $5 million or $500 million.”

The team will be able to simultaneously identify numerous E. coli genes and the results of turning these genes on or off using advanced technologies. Many of the technologies have been developed by the researchers’ own labs.

The grant is the first of its kind from the DOE’s Office of Biological and Environmental Research and was awarded to only seven other research groups including teams led by MIT, Purdue University and the J. Craig Venter Institute.

In 2011, CU’s Technology Transfer Office named Gill an inventor of the year. In 2005, Gill won a National Science Foundation CAREER Award as well as a National Institutes of Health K25 Career Development Award for genomics research and teaching.

For more information about the DOE grant and other awardees visit http://genomicscience.energy.gov/biosystemsdesign/biosystemsdesign2012fundedprojects.pdf. For more information about RASEI visit http://rasei.colorado.edu/.

Contacts
Ryan Gill, 303-492-2627


rtg@colorado.edu

November 28, 2012

Mark F. Meier, one of the nation's most prominent glaciologists, and a leader in the study of glacier melt's effect on rising on sea levels, died Sunday in Boulder. He was 86.

At the time of his death, Meier was director emeritus at Boulder's Institute of Arctic and Alpine Research (INSTAAR), where he served as director from 1985 to 1994. He also was professor emeritus of geological sciences at the University of Colorado. Meier moved to Boulder in 1985.

"He was one of the pioneers, when it comes to sea-level rise, basically telling people, 'This is a real phenomenon, this is going to happen, and you're not going to stop it unless you do something,'" said Jim White, current INSTAAR director. "And they didn't do anything."

White added, "Mark was where the rubber meets the road, in terms of translating science to society."

Hurricane Sandy caused its devastation to low-lying areas of the northeast United States less than a month before Meier's death. But Meier didn't need to see its wreckage to affirm what he'd been saying for years.

"I don't know that Mark needed vindication," White said. "Mark's understanding of the physics of melting ice, which is simple stuff, really, was profound. He knew what was going to happen. But he wasn't the type to sit back and say, 'See, I told you so.'"

The cascading effect from the proliferation of greenhouse gasses into the atmosphere, compounding recent urban nightmares such as flooded subways and tunnels, according to White, is what Meier had been forecasting "for a long time. This day was coming."

Tad Pfeffer, a fellow at INSTAAR and professor of civil, environmental and architectural engineering at CU, worked alongside Meier. He said Meier maintained his professional involvement in glacial studies long after stepping down at INSTAAR. Meier also kept up on his work a CU, authoring two professional papers as recently as 2009, and even took part in a seminar at INSTAAR shortly before Thanksgiving.

"The work that he is most well known for now," Pfeffer said, "is his work on global assessments of glaciers and ice caps all around the world; not just studying one glacier in detail, which he also did a lot of (most notably the massive Columbia Glacier on Prince William Sound in Alaska), but also looking at what all the glaciers are doing, and adding it up as a critical part of assessing present-day sea level rise -- as well as projecting it into the future."

Meier, an Iowa native, formed the glaciology department for the U.S. Geological Survey in 1956, and received his Ph.D. from the California Institute of Technology in 1957.

He took part in glaciological studies during the International Geophysical Year (1957-58), then directed the U.S. Geological Survey's Project Office -- Glaciology in Tacoma, Wash., until assuming the directorship post at INSTAAR.

During the International Geophysical Year and International Hydrological Decade (1965-1975), Meier was a principal organizer of systematic measurement and assessment of glacier mass balance in North America. He also was a pioneer in the use of remote sensing in glaciology, and the leader of investigations of tidewater glacier dynamics in Alaska.

His many awards and honors include the Distinguished Service Award of the U.S. Department of the Interior, as well as three medals from the USSR Academy of Sciences.

Meier, who is survived by his wife, Barbara, as well as his children and grandchildren, also made his mark as a painter. He favored working in acrylics. Meier's landscapes of high mountains and polar regions were featured in local exhibits.

"Some were very abstract," Pfeffer said. "And you could see that same kind of artistry in his scientific work, as well. Back when people drafted by hand, his maps were beautiful examples of calligraphy."

Contact Camera Staff Writer Charlie Brennan at 303-473-1327 or brennanc@dailycamera.com.

Source: http://www.dailycamera.com/science-environment/ci_22085000/boulders-mark-f-meier-pioneer-glacial-melt-study?source=email
 

November 26, 2012

The wild and dramatic cascade of ice into the ocean from Alaska’s Columbia Glacier, an iconic glacier featured in the documentary “Chasing Ice” and one of the fastest moving glaciers in the world, will cease around 2020, according to a study by the University of Colorado Boulder.

A computer model predicts the retreat of the Columbia Glacier will stop when the glacier reaches a new stable position -- roughly 15 miles upstream from the stable position it occupied prior to the 1980s. The team, headed by lead author William Colgan of the CU-Boulder headquartered Cooperative Institute for Research in Environmental Sciences, published its results today in The Cryosphere, an open access publication of the European Geophysical Union.

The Columbia Glacier is a large (425 square miles), multi-branched glacier in south-central Alaska that flows mostly south out of the Chugach Mountains to its tidewater terminus in Prince William Sound.

Warming air temperatures have triggered an increase in the Columbia Glacier’s rate of iceberg calving, whereby large pieces of ice detach from the glacier and float into the ocean, according to Colgan. “Presently, the Columbia Glacier is calving about 2 cubic miles of icebergs into the ocean each year -- that is over five times more freshwater than the entire state of Alaska uses annually,” he said. “It is astounding to watch.”

The imminent finish of the retreat, or recession of the front of the glacier, has surprised scientists and highlights the difficulties of trying to estimate future rates of sea level rise, Colgan said. “Many people are comfortable thinking of the glacier contribution to sea level rise as this nice predictable curve into the future, where every year there is a little more sea level rise, and we can model it out for 100 or 200 years,” Colgan said.

The team’s findings demonstrate otherwise, however. A single glacier’s contribution to sea level rise can “turn on” and “turn off” quite rapidly, over a couple of years, with the precise timing of the life cycle being difficult to forecast, he said. Presently, the majority of sea level rise comes from the global population of glaciers. Many of these glaciers are just starting to retreat, and some will soon cease to retreat.

“The variable nature and speed of the life cycle among glaciers highlights difficulties in trying to accurately predict the amount of sea level rise that will occur in the decades to come,” Colgan said.

The Columbia Glacier was first documented in 1794 when it appeared to be stable with a length of 41 miles. During the 1980s it began a rapid retreat and by 1995 it was only about 36 miles long. By late 2000 it was about 34 miles long.

The loss of a massive area of the Columbia Glacier’s tongue has generated a tremendous number of icebergs since the 1980s. After the Exxon Valdez ran aground while avoiding a Columbia Glacier iceberg in 1989, significant resources were invested to understand its iceberg production. As a result, Columbia Glacier became one of the most well-documented tidewater glaciers in the world, providing a bank of observational data for scientists trying to understand how a tidewater glacier reacts to a warming climate.

Motivated by the compelling imagery of the Columbia Glacier’s retreat documented in the Extreme Ice Survey -- James Balog’s collection of time-lapse photography of disappearing glaciers around the world -- Colgan became curious as to how long the glacier would continue to retreat. To answer this question, the team of researchers created a flexible model of the Columbia Glacier to reproduce different criteria such as ice thickness and terminus extent.

The scientists then compared thousands of outputs from the computer model under different assumptions with the wealth of data that exists for the Columbia Glacier.

The batch of outputs that most accurately reproduced the well-documented history of retreat was run into the future to predict the changes the Columbia Glacier will most likely experience until the year 2100. The researchers found that around 2020 the terminus of the glacier will retreat into water that is sufficiently shallow to provide a stable position through 2100 by slowing the rate of iceberg production.

The speediness of the glacier’s retreat is due to the unique nature of tidewater glaciers, Colgan said. When warming temperatures melt the surface of a land glacier, the land glacier only loses its mass by run-off. But in tidewater glaciers, the changes in ice thickness resulting from surface melt can create striking changes in ice flow, triggering an additional dynamic process for retreat.

The dynamic response of the Columbia Glacier to the surface melt will continue until the glacier reaches its new stable position in 2020, at roughly 26 miles long. “Once the dynamic trigger had been pulled, it probably wouldn’t have mattered too much what happened to the surface melt -- it was just going to continue retreating through the bedrock depression upstream of the pre-1980s terminus,” Colgan said.

Colgan next plans to attempt to use similar models to predict when the Greenland glaciers -- currently the major contributors to sea level rise -- will “turn off” and complete their retreats.

The future for the Columbia Glacier, however, looks bleak. “I think the hope was that once we saw climate change happening, we could act to prevent some irreversible consequences,” Colgan said, “but now we are only about eight years out from this retreat finishing -- it is really sad. There is virtually no chance of the Columbia Glacier recovering its pre-retreat dimensions on human time-scales.”

The study was funded by NASA, and co-authors on the paper include W. Tad Pfeffer of CU-Boulder’s Institute of Arctic and Alpine Research, Harihar Rajaram of the CU-Boulder Department of Civil, Environmental, and Architectural Engineering, Waleed Abdalati of the National Aeronautic and Space Administration in Washington, D.C., and Balog of the Extreme Ice Survey in Boulder, Colo.

The complete study is available online at http://www.the-cryosphere.net/6/1395/2012/.

Contact:


William Colgan, CIRES, 011-45-5290-1585


William.Colgan@colorado.edu


Jane Palmer, CIRES science writer, 303-883-4398


Jane.Palmer@colorado.edu

November 13, 2012

Analysis of 90 years of observational data has revealed that summer climates in regions across the globe are changing -- mostly, but not always, warming --according to a new study led by a scientist from the Cooperative Institute for Research in Environmental Sciences headquartered at the University of Colorado Boulder.

“It is the first time that we show on a local scale that there are significant changes in summer temperatures,” said lead author CIRES scientist Irina Mahlstein. “This result shows us that we are experiencing a new summer climate regime in some regions.”

The technique, which reveals location-by-location temperature changes rather than global averages, could yield valuable insights into changes in ecosystems on a regional scale. Because the methodology relies on detecting temperatures outside the expected norm, it is more relevant to understand changes to the animal and plant life of a particular region, which scientists would expect to show sensitivity to changes that lie outside of normal variability.

“If the summers are actually significantly different from the way that they used to be, it could affect ecosystems,” said Mahlstein, who works in the Chemical Sciences Division of the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory.

To identify potential temperature changes, the team used climate observations recorded from 1920 to 2010 from around the globe. The scientists termed the 30-year interval from 1920 to 1949 the “base period,” and then compared the base period to other 30-year test intervals starting every 10 years since 1930.

The comparison used statistics to assess whether the test interval differed from the base period beyond what would be expected due to yearly temperature variability for that geographical area.

Their analysis found that some changes began to appear as early as the 1960s, and the observed changes were more prevalent in tropical areas. In these regions, temperatures varied little throughout the years, so the scientists could more easily detect any changes that did occur, Mahlstein said.

The scientists found significant summer temperature changes in 40 percent of tropical areas and 20 percent of higher-latitude areas. In the majority of cases, the researchers observed warming summer temperatures, but in some cases they observed cooling summer temperatures.

“This study has applied a new approach to the question, ‘Has the temperature changed in local areas?’ ” Mahlstein said. The study is in press in the journal Geophysical Research Letters, a publication of the American Geophysical Union.

The study’s findings are consistent with other approaches used to answer the same question, such as modeling and analysis of trends, Mahlstein said. But this technique uses only observed data to come to the same result. “Looking at the graphs of our results, you can visibly see how things are changing,” she said.
In particular the scientists were able to look at the earlier time periods, note the temperature extremes, and observe that those values became more frequent in the later time periods. “You see how the extreme events of the past have become a normal event,” Mahlstein said.

The scientists used 90 years of data for their study, a little more than the average lifespan of a human being. So if inhabitants of those areas believe that summers have changed since they were younger, they can be confident it is not a figment of their imagination.

“We can actually say that these changes have happened in the lifetime of a person,” Mahlstein said.
Co-authors on the study were Gabriele Hegerl from the University of Edinburgh in Scotland and Susan Solomon from Massachusetts Institute of Technology.

CIRES is a joint institute of CU-Boulder and NOAA.

Contact:

Irina Mahlstein, CIRES, 303-497-4746


Irina.Mahlstein@noaa.gov


Jane Palmer, CIRES science writer, 303-883-4398


Jane.Palmer@colorado.edu