Warm ocean drives most Antarctic ice shelf loss, UC Irvine and others show

Findings are a game changer for future forecasts about thawing continent

2013-06-14

(Press-News.org) Irvine, Calif. – Ocean waters melting the undersides of Antarctic ice shelves, not icebergs calving into the sea, are responsible for most of the continent's ice loss, a study by UC Irvine and others has found.

The first comprehensive survey of all Antarctic ice shelves discovered that basal melt, or ice dissolving from underneath, accounted for 55 percent of shelf loss from 2003 to 2008 – a rate much higher than previously thought. Ice shelves, floating extensions of glaciers, fringe 75 percent of the vast, frozen continent.

The findings, to be published in the June 14 issue of Science, will help scientists improve projections of how Antarctica, which holds about 60 percent of the planet's freshwater locked in its massive ice sheet, will respond to a warming ocean and contribute to sea level rise.

It turns out that the tug of seawaters just above the freezing point matters more than the breaking off of bergs.

"We find that iceberg calving is not the dominant process of ice removal. In fact, ice shelves mostly melt from the bottom before they even form icebergs," said lead author Eric Rignot, a UC Irvine professor who's also a researcher with NASA's Jet Propulsion Laboratory in Pasadena. "This has profound implications for our understanding of interactions between Antarctica and climate change. It basically puts the Southern Ocean up front as the most significant control on the evolution of the polar ice sheet."

Ice shelves grow through a combination of land ice flowing to the sea and snow falling on their surfaces. The researchers combined a regional snow accumulation model and a new map of Antarctica's bedrock with ice shelf thickness, elevation and velocity data captured by Operation IceBridge – an ongoing NASA aerial survey of Greenland and the South Pole. (Rignot will host a planning session of Operation IceBridge scientists at UC Irvine on June 17 and 18.)

Ocean melting is distributed unevenly around the continent. The three giant ice shelves of Ross, Filchner and Ronne, which make up two-thirds of Antarctica's ice shelves, accounted for only 15 percent. Meanwhile, less than a dozen small ice shelves floating on relatively warm waters produced half the total meltwater during the same period.

The researchers also compared the rates at which the ice shelves are shedding ice with the speed at which the continent itself is losing mass and found that, on average, the shelves lost mass twice as fast as the Antarctic ice sheet did.

"Ice shelf melt can be compensated by ice flow from the continent," Rignot said. "But in a number of places around Antarctica, they are melting too fast, and as a consequence, glaciers and the entire continent are changing."

### Other authors are Jeremie Mouginot and Bernd Scheuchl of UC Irvine and Stanley Jacobs of Columbia University. Funding was provided by NASA, the National Science Foundation, and the National Oceanic & Atmospheric Administration.

About the University of California, Irvine: Founded in 1965, UCI is a top-ranked university dedicated to research, scholarship and community service. Led by Chancellor Michael Drake since 2005, UCI is among the most dynamic campuses in the University of California system, with more than 28,000 undergraduate and graduate students, 1,100 faculty and 9,400 staff. Orange County's second-largest employer, UCI contributes an annual economic impact of $4.3 billion. For more UCI news, visit news.uci.edu.

News Radio: UCI maintains on campus an ISDN line for conducting interviews with its faculty and experts. Use of this line is available for a fee to radio news programs/stations that wish to interview UCI faculty and experts. Use of the ISDN line is subject to availability and approval by the university.

Contact: Janet Wilson UCI maintains an online directory of faculty available as experts to the media. To access, visit http://www.today.uci.edu/experts.

ELSE PRESS RELEASES FROM THIS DATE:

Study: Context crucial when it comes to mutations in genetic evolution

2013-06-14

With mutations, it turns out that context can be everything in determining whether or not they are beneficial to their evolutionary fate. According to the traditional view among biologists, a central tenet of evolutionary biology has been that the evolutionary fates of new mutations depend on whether their effects are good, bad or inconsequential with respect to reproductive success. Central to this view is that "good" mutations are always good and lead to reproductive success, while "bad" mutations are always bad and will be quickly weeded out of the gene pool. However, ...

Exoplanet formation surprise

2013-06-14

Washington, D.C.—-A team of researchers has discovered evidence that an extrasolar planet may be forming quite far from its star—- about twice the distance Pluto is from our Sun. The planet lies inside a dusty, gaseous disk around a small red dwarf TW Hydrae, which is only about 55 percent of the mass of the Sun. The discovery adds to the ever-increasing variety of planetary systems in the Milky Way. The research is published in the Astrophysical Journal.* This dusty protoplanetary disk is the closest one to us, some 176 light-years away in the constellation Hydra. The ...

Farmworkers feel the heat even when they leave the fields

2013-06-14

WINSTON-SALEM, N.C. – June 13, 2013 – Hot weather may be the work environment for the 1.4 million farmworkers in the United States who harvest crops, but new research shows that these workers continue to experience excessive heat and humidity even after leaving the fields. Wake Forest Baptist Medical Center researchers conducted a study to evaluate the heat indexes in migrant farmworker housing and found that a majority of the workers don't get a break from the heat when they're off the clock. Lead author Sara A. Quandt, Ph.D., a professor of epidemiology and prevention ...

Depression in postmenopausal women may increase diabetes and cardiovascular disease risk

2013-06-14

WORCESTER — Postmenopausal women who use antidepressant medication or suffer from depression might be more likely to have a higher body mass index (BMI), larger waist circumference and inflammation—all associated with increased risk for diabetes and cardiovascular disease, according to a study led by University of Massachusetts Medical School investigator Yunsheng Ma, PhD, MD, MPH, and published in the June 13 issue of the American Journal of Public Health. The UMass Medical School study investigated whether elevated depressive symptoms and antidepressant use are associated ...

Black locust showing promise for biomass potential

2013-06-14

URBANA, Ill. – Researchers from the Energy Biosciences Institute at the University of Illinois, evaluating the biomass potential of woody crops, are taking a closer look at the black locust (Robinia pseudoacacia), which showed a higher yield and a faster harvest time than other woody plant species that they evaluated, said U of I associate professor of crop sciences Gary Kling. "For now the only thing you can do with it is use it for direct combustion," Kling said. "But if it becomes a major crop other researchers could start working on the process of how to break it ...

Tobacco laws for youth may reduce adult smoking

2013-06-14

States that want to reduce rates of adult smoking may consider implementing stringent tobacco restrictions on teens, suggests a new study by researchers at Washington University School of Medicine in St. Louis. The researchers discovered that states with more restrictive limits on teens purchasing tobacco also have lower adult smoking rates, especially among women. And compared with states with less restrictive limits, they also tend to have fewer adult heavy smokers. The study is published online June 13 in the American Journal of Public Health. "In most states for ...

Dangerous strains of E. coli may linger longer in water than benign counterparts, study finds

2013-06-14

BUFFALO, N.Y. — A toxin dangerous to humans may help E. coli fend off aquatic predators, enabling strains of E. coli that produce the toxin to survive longer in lake water than benign counterparts, a new study finds. Researchers from the University at Buffalo and Mercyhurst University reported these results online June 7 in the journal Applied and Environmental Microbiology. "The take-home lesson is that E. coli that produce Shiga toxin persisted longer in recreational water than E. coli that don't produce this toxin," said UB Professor of Biological Sciences Gerald ...

Nanoparticle opens the door to clean-energy alternatives

2013-06-14

Cheaper clean-energy technologies could be made possible thanks to a new discovery. Research team members led by Raymond Schaak, a professor of chemistry at Penn State University, have found that an important chemical reaction that generates hydrogen from water is effectively triggered -- or catalyzed -- by a nanoparticle composed of nickel and phosphorus, two inexpensive elements that are abundant on Earth. The results of the research will be published in the Journal of the American Chemical Society. Schaak explained that the purpose of the nickel phosphide nanoparticle ...

Monell-led research identifies scent of melanoma

2013-06-14

PHILADELPHIA (June 13, 2013) -- According to new research from the Monell Center and collaborating institutions, odors from human skin cells can be used to identify melanoma, the deadliest form of skin cancer. In addition to detecting a unique odor signature associated with melanoma cells, the researchers also demonstrated that a nanotechnology-based sensor could reliably differentiate melanoma cells from normal skin cells. The findings suggest that non-invasive odor analysis may be a valuable technique in the detection and early diagnosis of human melanoma. Melanoma ...

Autonomous energy-scavenging micro devices will test water quality, monitor bridges, more

2013-06-14

Out in the wilds or anywhere off the grid, sophisticated instruments small enough to fit in a shirt pocket will one day scavenge power from sunlight, body heat, or other sources to monitor water quality or bridge safety, enabling analysis in the field rather than bringing samples and data back to the lab. Researchers at the University of Waterloo in Ontario are using optics and photonics in their quest to "bring the lab to the sample," said lead researcher Vassili Karanassios of the Department of Chemistry and of the university's Institute for Nanotechnology (WIN). A ...

Warm ocean drives most Antarctic ice shelf loss, UC Irvine and others show

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: