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Study Says Antarctic Glaciers Are Shrinking, Sea Levels May Climb

Friday, April 22, 2005; Page A09

Most of the coastal glaciers along the 1,200-mile Antarctic Peninsula have shrunk as temperatures have risen over the past 50 years, and sea levels may climb if the trend continues, according to a study published today in the journal Science.

About 212 of the 244 glaciers surrounding the peninsula, which stretches north from the southern polar continent toward South America, have retreated as temperatures have risen more than 4.5 degrees Fahrenheit since the 1950s, reported the study by Alison Cook and colleagues.

Satellite images show the retreat of glaciers on the Antarctic Peninsula. The photo on the left was taken in 1986, the one at right in 2001. (Reuters)

The glacial retreat puts Antarctic ice shelves and sheets at risk, wrote Cook, a geographic data analyst with the British Antarctic Survey in Cambridge, England, and the study's lead author. Inland glaciers that flow from mountains into the ocean and keep continental ice sheets in place are retreating, Cook said.

"We can expect more retreat to happen across the peninsula," Cook said in a telephone interview from Cambridge. "The glaciers haven't disappeared, though they are still moving backward, and I think we will definitely see more of that if the climate continues to warm in the same way."

The Antarctic Peninsula is a mountainous region that extends from the 14 million-square-mile continent and ends 600 miles from the tip of Argentina. Its eastern side is flanked by the Larsen ice shelf, a floating ice mass that broke from the main continent in 2002.

The authors used more than 2,000 aerial photographs taken from 1940 to 2001 and more than 100 satellite pictures taken after the 1960s to make maps of the peninsula, then compared them with a composite of images from NASA's Landsat satellites.

The research is part of a U.S. Geological Survey study of the entire continent.

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