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Greenland ice sheet meltdown: It's spreading, study finds

March 24, 2010 | 12:46 pm

Icemelt

Scientists studying global warming have shifted attention to northwestern Greenland, where new evidence is showing that the melting of ice sheets has spread.

Melting attributed to the buildup of greenhouse gases in the atmosphere has been well documented in the southern portion of Greenland's ice sheet, which contains about 20% of the planet's ice -- enough to cause an ocean rise of 21 feet if it all melts.

A team led by the Denmark Technical Institute's National Space Institute in Copenhagen used data from NASA and GPS measurements to document crustal uplift caused by the loss of ice mass pressing down on bedrock. 

"This is a phenomenon that was undocumented before this study," said University of Colorado Boulder physics professor and study co-author John Wahr. "Our speculation is that some of the big glaciers in this region are sliding downhill faster and dumping more ice in the ocean."

The scientists believe accelerated ice loss began moving up the northwestern coast in late 2005.

Other co-authors on the study included Michael Bevis and Eric Kendrick from Ohio State University and Isabella Velicogna of UC Irvine, who also is a scientist at NASA's Jet Propulsion Laboratory. It was printed in Geophysical Research Letters, a publication of the American Geophysical Union.

"These changes on the Greenland ice sheet are happening fast, and we are definitely losing more ice mass than we had anticipated, " said Velicogna. "We also are seeing this ice mass loss trend in Antarctica, a sign that warming temperatures really are having an effect on ice in Earth's cold regions."

Researchers estimate that if melting in northwestern Greenland accelerates in major glaciers in the area, such as the Humboldt Glacier and the Peterman Glacier, Greenland's total ice loss could be increased by an additional 12 to 24 cubic miles within a few years.

Average air temperatures above Greenland's ice sheets have risen 4 degrees Fahrenheit since 1991.

-- Geoffrey Mohan

Photo: Melting of a Greenland glacier in 2005. Credit: John McConnico / Associated Press

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