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Ice shelf collapse causes glacial surge

By Melanie J. Martin - 27 Jul 2011 14:50:0 GMT
Ice shelf collapse causes glacial surge

Collapsing ice shelves send glacial ice surging into the ocean, possibly for decades, new research shows.

Glaciers supply ice to ice shelves, thick layers of ice fixed to a land mass. Without ice shelves to slow their progress, gravity causes glaciers to surge into the ocean instead of adding a top layer to the ice shelf.

Researchers in an earlier study described ice shelves as "major dams for the inland ice," without which the glacial ice cascades into the sea.

Just how much does the collapse of an ice shelf affect glaciers? Researchers from the University of Maryland, the University of Toulouse, France, and the University of Colorado have provided the most accurate picture thus far, according to NASA.

The researchers studied the ice loss of the main glaciers feeding two ice shelves that collapsed in 1995 and 2002, the Larsen A and B ice shelves in the Antarctic. To create maps of the ice loss, they used satellite data from NASA and CNES, a French space agency, along with data from aircraft missions.

Some glaciers quickly dropped over 500 feet in elevation, say the researchers. From 2001 to 2006, ice loss averaged at least 11.2 billion tons per year. From 2006 to 2010, ice loss averaged 10.2 billion tons, illustrating that inland ice loss may take many years to slow significantly.

Glaciers and ice shelves contribute to rising sea levels as they surge into the ocean. Ice shelves grow slowly, as glaciers add layer after layer of ice, and can shrink slightly as icebergs break off. Ice shelves can last for thousands of years, but over the past 30 years, Antarctic ice shelves and those on Canada's northern coast have disintegrated quickly, says the National Snow and Ice Data Center (NSIDC) at the University of Colorado, Boulder. Researchers believe climate change may play a major role in ice shelf collapse.

Top Image: The Landsat Image Mosaic of Antarctica (LIMA) provides this "flyover" view of the Larsen Ice Shelfés long reach out into the Weddell Sea. (Credit: LIMA)