Magazine article Science News

Antartic Glacier Thins and Speeds Up

Magazine article Science News

Antartic Glacier Thins and Speeds Up

Article excerpt

One of the largest glaciers in Antartica is thinning according to satellite measurements. The finding spurs concerns that changes in the glacier's ice shelf along the Antartic coast may increase the amount of ice that drains from the interior of the continent and floats out to sea.

Each year, the 200-kilometer-long, 25km-wide Pine Island Glacier depletes the Weat Antartic Ice Sheet of about 69 cubic kilometers of ice. Eventually the glacier flows into the sea, where it forms a floating ice shelf about 40km wide, says Andrew Shepherd, a physicist at University College London. When he and his colleagues analyzed satellite measurement taken between 1992 and 1999, they found that large portions of the Pine Island Glacier thinned during that period. The British scientist report their findings in the Feb. 2 SCIENCE.

At the point called the grounding line, where the glacier reaches the ocean and the ice lifts off the bedrock and floats, the 700-meter-thick ice thinned by about 1.6 m annually during the period studied. As distance inland increased, the glacier showed less thinning.

Much of the Pine Island Glacier rests on bedrock that lies more than 1 km below sea level, says Shephered. If the glacier continues to thin at the current rate, large parts of it would be afloat within 600 years--a development that could accelerate the flow of ice off the continent.

Because the bedrock under the Pipe Island Glacier slopes inward toward the center of the continent, the ice stream has to march uphill quite a distance before it again flow downhill at the coast. …

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