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.
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.
UCI maintains an online directory of faculty available as experts to the media. To access, visit http://www.today.uci.edu/experts
Janet Wilson | EurekAlert!
Fossil coral reefs show sea level rose in bursts during last warming
19.10.2017 | Rice University
NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Materials Sciences
19.10.2017 | Materials Sciences
19.10.2017 | Physics and Astronomy