Saturday, March 27, 2010

Ice melt spreads to both coasts of Greenland

Futurity,org: Ice loss from the Greenland ice sheet, which has been increasing during the past decade over its southern region, is now making an upward climb on its northwest coast as well. An international team of scientists compared data from NASA’s Gravity and Recovery Climate Experiment (GRACE) satellite system with continuous GPS measurements made from long-term sites on bedrock on the edges of the ice sheet.

The data from the GPS and GRACE provided the researchers with monthly averages of crustal uplift caused by ice-mass loss. The team combined the uplift measured by GRACE over United Kingdom-sized chunks of Greenland while the GPS receivers monitor crustal uplift on scales of just tens of miles.

“When we look at the monthly values from GRACE, the ice mass loss has been very dramatic along the northwest coast of Greenland,” says John Wahr, professor of physics at the University of Colorado, Boulder. “This is a phenomenon that was undocumented before this study. Our speculation is that some of the big glaciers in this region are sliding downhill faster and dumping more ice in the ocean.”

The team found that uplift rates near the Thule Air Base on Greenland’s northwest coast rose by roughly 1.5 inches, or about 4 centimeters, from October 2005 to August 2009. “Our results show that the ice loss, which has been well documented over southern portions of Greenland, is now spreading up along the northwest coast,” says Wahr’s colleague Shfaqat Abbas Khan, of Denmark’s Technical Institute’s National Space Institute in Copenhagen and lead author on a paper in Geophysical Research Letters.

Although the low resolution of GRACE—a swath of about 155 miles, or 250 kilometers across—is not precise enough to pinpoint the source of the ice loss, the fact that the ice sheet is losing mass nearer to the ice sheet margins suggests the flows of Greenland outlet glaciers there are increasing in velocity….

Cape York Greenland Photograped by Mila Zinkova in September of 2005, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License

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