Published: September 03, 2008 06:44 pm            

Arctic ice cover sees near-record retreat

TORONTO — The Arctic Ocean's ice cover has suffered its second-largest retreat in at least three decades this summer, including a nearly Manhattan-sized ice shelf that broke completely from an island in Canada's polar frontier and went adrift, scientists said.

The region's ice shelf over the summer has lost 82 square miles (212 square kilometers), reducing the Arctic Ocean ice cover to its second-biggest retreat since satellite measurements began 30 years ago, Martin Jeffries of the U.S. National Science Foundation and University of Alaska Fairbanks, said in a statement Tuesday.

"These changes are irreversible under the present climate and indicate that the environmental conditions that have kept these ice shelves in balance for thousands of years are no longer present," said Derek Mueller, an Arctic ice shelf specialist at Trent University in Ontario.

Formed by accumulating snow and freezing meltwater, ice shelves are large platforms of thick, ancient sea ice that float on the ocean's surface but are connected to land.

During the last century, when ice shelves would break off, thick sea ice would eventually reform in their place and eventually over time, compression, continuous movement in the ocean and icy temperatures would help to create another ice shelf.

"But today, warmer temperatures and a changing climate means there's no hope for regrowth. A scary scenario," said Mueller.

Mueller told The Associated Press on Wednesday that the 4,500-year-old Markham Ice Shelf separated from Ellesmere Island in early August and the 19-square-mile (49-square-kilometer) shelf is now adrift in the Arctic Ocean.

"The Markham Ice Shelf was a big surprise because it suddenly disappeared. We went under cloud for a bit during our research and when the weather cleared up, all of a sudden there was no more ice shelf. It was a shocking event that underscores the rapidity of changes taking place in the Arctic," said Mueller.

Mueller also said that two large sections of ice detached from the Serson Ice Shelf, shrinking that ice feature by 47 square miles (122 square kilometers), or 60 percent, and that the Ward Hunt Ice Shelf has also continued to break up, losing an additional 8 square miles (21 square kilometers).

Mueller reported last month that 7 square miles (18 square kilometers) of the 170-square-mile (440-square-kilometer) and 130-feet-thick (40-meters-thick) Ward Hunt shelf had broken off.

These developments come on the heels of unusual cracks in a northern Greenland glacier, rapid melting of a southern Greenland glacier, and a near record loss for Arctic sea ice this summer. At the other end of the globe, a 160-square-mile (414-square kilometer) chunk of an Antarctic ice shelf disintegrated earlier this year.

"Reduced sea ice conditions and unusually high air temperatures have facilitated the ice shelf losses this summer," said Luke Copland, director of the Laboratory for Cryospheric Research at the University of Ottawa. "And extensive new cracks across remaining parts of the largest remaining ice shelf, the Ward Hunt, mean that it will continue to disintegrate in the coming years."

Ellesmere Island was once entirely ringed by a single enormous ice shelf that broke up in the early 1900s. All that is left today are the four much smaller shelves that together cover little more than 299 square miles (774 square kilometers).

The loss of these ice shelves means that rare ecosystems that depend on them are on the brink of extinction, said Warwick Vincent, director of Laval University's Centre for Northern Studies and a researcher in the program ArcticNet.

Along with decimating ecosystems, drifting ice shelves and warmer temperatures that will cause further melting ice pose a hazard to populated shipping routes in the Arctic region — a phenomenon that Canada's Prime Minister Stephen Harper seems to welcome.

Harper announced last week that he plans to expand exploration of the region's known oil and mineral deposits, a possibility that has become more evident as a result of melting sea ice. It is the burning of oil and other fossil fuels that scientists say is the chief cause of manmade warming and melting ice.



Copyright 2008 The Associated Press.

        

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