Featured Research

from universities, journals, and other organizations

West Antarctic Ice Sheet May Not Be Losing Ice As Fast As Once Thought

Date:
October 20, 2009
Source:
University of Texas at Austin
Summary:
New ground measurements suggest the rate of ice loss of the West Antarctic ice sheet has been slightly overestimated. For the first time, researchers have directly measured the vertical motion of the bedrock at sites across West Antarctica using GPS. The results will lead to more accurate estimates of ice mass loss.

The West Antarctic ice sheet rests on a bed well below sea level and is drained by much larger outlet glaciers and ice streams that accelerate over distances of hundreds of kilometers before reaching the ocean, often through large floating ice shelves.
Credit: NASA/LIMA

New ground measurements made by the West Antarctic GPS Network (WAGN) project, composed of researchers from The University of Texas at Austin, The Ohio State University, and The University of Memphis, suggest the rate of ice loss of the West Antarctic ice sheet has been slightly overestimated.

"Our work suggests that while West Antarctica is still losing significant amounts of ice, the loss appears to be slightly slower than some recent estimates," said Ian Dalziel, lead principal investigator for WAGN. "So the take home message is that Antarctica is contributing to rising sea levels. It is the rate that is unclear."

In 2006, another team of researchers used data from the Gravity Recovery and Climate Experiment (GRACE) satellites to infer a significant loss of ice mass over West Antarctica from 2002 to 2005. The GRACE satellites do not measure changes in ice loss directly but measure changes in gravity, which can be caused both by ice loss and vertical uplift of the bedrock underlying the ice.

Now, for the first time, researchers have directly measured the vertical motion of the bedrock at sites across West Antarctica using the Global Positioning System (GPS). The results should lead to more accurate estimates of ice mass loss.

Antarctica was once buried under a deeper and more extensive layer of ice during a period known as the Last Glacial Maximum. Starting about 20,000 years ago, the ice began slowly thinning and retreating. As the ice mass decreases, the bedrock immediately below the ice rises, an uplift known as postglacial rebound.

Postglacial rebound causes an increase in the gravitational attraction measured by the GRACE satellites and could explain their inferred measurements of recent, rapid ice loss in West Antarctica. The new GPS measurements show West Antarctica is rebounding more slowly than once thought. This means that the correction to the gravity signal from the rock contribution has been overestimated and the rate of ice loss is slower than previously interpreted.

"The published results are very important because they provide precise, ground-truth GPS observations of the actual rebound of the continent due to the loss of ice mass detected by the GRACE satellite gravity measurements over West Antarctica" said Vladimir Papitashvili, acting director for the Antarctic Earth Sciences Program at the National Science Foundation, which supported the research.

WAGN researchers do not yet know how large the overestimation was. A more definitive correction will be conducted by other researchers who specialize in interpreting GRACE data. Previous estimates of postglacial rebound were made with theoretical models. Assimilation of the direct GPS results into new models will therefore produce significant improvements in estimations of ice mass loss.

The results will appear in the electronic journal Geochemistry, Geophysics, Geosystems of the American Geophysical Union and the American Geochemical Society.

A team from The University of Texas at Austin's Jackson School of Geosciences (Ian Dalziel, lead principal investigator), The Ohio State University's School of Earth Sciences (Michael Bevis), and The University of Memphis' Center for Earthquake Research and Information (Robert Smalley, Jr.) performed the WAGN project.

The network consists of 18 GPS stations installed on bedrock outcrops across West Antarctica. Precise, millimeter level, three-dimensional locations of the stations, which are bolted into the bedrock, were determined during measurements made from 2001 to 2003 and from 2004 to 2006, the two measurements being at least three years apart. The difference in the positions during the two time periods indicates the motion of the bedrock.

The WAGN data were supplemented with data from the first year of the Polar Earth Observing Network (POLENET) project, a project to establish a more sophisticated, continuously recording network of GPS and seismic stations, including the already established WAGN sites. POLENET will further improve our understanding of the interaction between the solid earth and ice sheets at both poles. The lead principal investigator of the U.S. Antarctic contribution to POLENET is Terry Wilson of The Ohio State University.

The West Antarctic GPS Network and the U.S. Antarctic contribution to the Polar Earth Observing Network of the International Polar Year were both funded and logistically supported by the Office of Polar Programs of the National Science Foundation.


Story Source:

The above story is based on materials provided by University of Texas at Austin. Note: Materials may be edited for content and length.


Journal Reference:

  1. Bevis et al. Geodetic measurements of vertical crustal velocity in West Antarctica and the implications for ice mass balance. Geochemistry Geophysics Geosystems, 2009; 10 (10): Q10005 DOI: 10.1029/2009GC002642

Cite This Page:

University of Texas at Austin. "West Antarctic Ice Sheet May Not Be Losing Ice As Fast As Once Thought." ScienceDaily. ScienceDaily, 20 October 2009. <www.sciencedaily.com/releases/2009/10/091019122838.htm>.
University of Texas at Austin. (2009, October 20). West Antarctic Ice Sheet May Not Be Losing Ice As Fast As Once Thought. ScienceDaily. Retrieved August 30, 2014 from www.sciencedaily.com/releases/2009/10/091019122838.htm
University of Texas at Austin. "West Antarctic Ice Sheet May Not Be Losing Ice As Fast As Once Thought." ScienceDaily. www.sciencedaily.com/releases/2009/10/091019122838.htm (accessed August 30, 2014).

Share This




More Earth & Climate News

Saturday, August 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Volcano Erupts on Papua New Guinea

Raw: Volcano Erupts on Papua New Guinea

AP (Aug. 29, 2014) Several communities were evacuated and some international flights were diverted on Friday after one of the most active volcanos in the region erupts. (Aug. 29) Video provided by AP
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Scientists Have Figured Out Why Rocks Move In Death Valley

Scientists Have Figured Out Why Rocks Move In Death Valley

Newsy (Aug. 28, 2014) The mystery of the moving rocks in Death Valley, California, has finally been solved. Scientists are pointing to a combo of water, ice and wind. Video provided by Newsy
Powered by NewsLook.com
Big Waves, Minor Flooding from Hurricane

Big Waves, Minor Flooding from Hurricane

AP (Aug. 27, 2014) Thundering surf spawned by Hurricane Marie pounded the Southern California coast Wednesday, causing minor flooding in a low-lying beach town. High surf warnings were posted for Los Angeles County south through Orange County. (Aug. 27) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins