Greenland icecap thickens slightly despite warming

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Greenland icecap thickens slightly despite warming

Reuters
October 20, 2005

OSLO (Reuters) - Greenland's ice-cap has thickened slightly in recent years despite wide predictions of a thaw triggered by global warming, a team of scientists said on Thursday.

The 3,000-meter (9,842-feet) thick ice-cap is a key concern in debates about climate change because a total melt would raise world sea levels by about 7 meters. And a runaway thaw might slow the Gulf Stream that keeps the North Atlantic region warm.

But satellite measurements showed that more snowfall was falling and thickening the ice-cap, especially at high altitudes, according to the report in the journal Science.

Glaciers at sea level have been retreating fast because of a warming climate, making many other scientists believe the entire ice-cap was thinning.

"The overall ice thickness changes are ... approximately plus 5 cms (1.9 inches) a year or 54 cms (21.26 inches) over 11 years," according to the experts at Norwegian, Russian and U.S. institutes led by Ola Johannessen at the Mohn Sverdrup center for Global Ocean Studies and Operational Oceanography in Norway.

However, they said that the thickening seemed consistent with theories of global warming, blamed by most experts on a build-up of heat-trapping gases from (32.00F).

And the scientists said that the thickening of the ice-cap might be offset by a melting of glaciers around the fringes of Greenland. Satellite data was not good enough to measure the melt nearer sea level.

ICE SHEETS

Most models of global warming indicate that the Greenland ice might melt within thousands of years if warming continues.

Oceans would rise by about 70 meters if the far bigger ice-cap on Antarctica melted along with Greenland. Antarctica's vast size acts as a deep freeze likely to slow any melt of the southern continent.

The panel that advises the United Nations has predicted that global sea levels might rise by almost a meter by 2100 because of a warming climate.
Such a rise would swamp low-lying Pacific islands and warming could trigger more hurricanes, droughts, spread deserts and drive thousands of species to extinction.

Still, a separate study in Science on Thursday said sea levels were probably rising slightly because of a melt of ice sheets.

"Ice sheets now appear to be contributing modestly to sea level rise because warming has increased mass loss from coastal areas more than warming has increased mass gain from enhanced snowfall in cold central regions," it said.

"Greenland presently makes the largest contribution to sea level rise," according to the report by scientists led by Richard Alley of Pennsylvania State University in the United States.


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Thinning Iceland Icecap


Scientists who want to monitor the state of our global climate may have to look no farther than the coastal ice that surrounds the Earth’s largest island.

A NASA study of Greenland’s ice sheet reveals that it is rapidly thinning. In an article published in the July 21 issue of Science, Bill Krabill, project scientist at the NASA Goddard Space Flight Center’s Wallops Flight Facility, Wallops Island, VA, reports that the frozen area around Greenland is thinning, in some places, at a rate of more than three feet per year. Any change is important since a smaller ice sheet could result in higher sea levels.

“A conservative estimate, based on our data, indicates a net loss of approximately 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise global sea level by 0.005 inches per year, or approximately seven percent of the observed rise,” Krabill said.

“This amount of sea level rise does not threaten coastal regions, but these results provide evidence that the margins of the ice sheet are in a process of change,” Krabill said. “The thinning cannot be accounted for by increased melting alone. It appears that ice must be flowing more quickly into the sea through glaciers.”

For further information on the Greenland mapping project, including the technology behind the science, visit the Airborne Topographic Mapper site.

To see more images of Greenland’s icecap, visit the Goddard Scientific Visualization Studio.


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