Tuesday, January 16, 2007

"The Warming of Greenland"

From the New York Times








Maps of the region show a mountainous peninsula covered with glaciers. The island’s distinct shape — like a hand with three bony fingers pointing north — looks like the end of the peninsula.

Now, where the maps showed only ice, a band of fast-flowing seawater ran between a newly exposed shoreline and the aquamarine-blue walls of a retreating ice shelf. The water was littered with dozens of icebergs, some as large as half an acre; every hour or so, several more tons of ice fractured off the shelf with a thunderous crack and an earth-shaking rumble.

All over Greenland and the Arctic, rising temperatures are not simply melting ice; they are changing the very geography of coastlines. Nunataks — “lonely mountains” in Inuit — that were encased in the margins of Greenland’s ice sheet are being freed of their age-old bonds, exposing a new chain of islands, and a new opportunity for Arctic explorers to write their names on the landscape.

“We are already in a new era of geography,” said the Arctic explorer Will Steger. “This phenomenon — of an island all of a sudden appearing out of nowhere and the ice melting around it — is a real common phenomenon now.”...

With 27,555 miles of coastline and thousands of fjords, inlets, bays and straits, Greenland has always been hard to map. Now its geography is becoming obsolete almost as soon as new maps are created....

The sudden appearance of the islands is a symptom of an ice sheet going into retreat, scientists say. Greenland is covered by 630,000 cubic miles of ice, enough water to raise global sea levels by 23 feet.

Carl Egede Boggild, a professor of snow-and-ice physics at the University Center of Svalbard, said Greenland could be losing more than 80 cubic miles of ice per year.

He discovered an island himself a year ago while flying over northwestern Greenland. “Suddenly I saw an island with glacial ice on it,” he said. “I looked at the map and it should have been a nunatak, but the present ice margin was about 10 kilometers away. So I can say that within the last five years the ice margin had retreated at least 10 kilometers.”....

“The general thinking until very recently was that ice sheets don’t react very quickly to climate,” said Martin Truffer, a glaciologist at the University of Alaska at Fairbanks. “But that thinking is changing right now, because we’re seeing things that people have thought are impossible.”

A study in The Journal of Climate last June observed that Greenland had become the single largest contributor to global sea-level rise....

There is no consensus on how much Greenland’s ice will melt in the near future, Dr. Alley said, and no computer model that can accurately predict the future of the ice sheet. Yet given the acceleration of tidewater-glacier melting, a sea-level rise of a foot or two in the coming decades is entirely possible, he said. That bodes ill for island nations and those who live near the coast...

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