Three Ice Shelves Breaking Up in Arctic

Sept. 3, 2008 -- Two ice shelves in Canada's far north have lost massive sections since August while a third ice shelf now is adrift in the Arctic Ocean, said researchers Wednesday who blamed climate change.

The entire 50 square-kilometer (19 square-mile) Markham Ice Shelf off the coast of Ellesmere Island broke away in early August and is now adrift, while two sections of the nearby Serson Ice Shelf detached, reducing its mass by 60 percent or 122 square kilometers (47 square miles).

Ward Hunt Ice Shelf, which halved in July, lost an additional 22 square kilometers (8.5 square miles).

"These changes are irreversible under the present climate and indicate that the environmental conditions that have kept these ice shelves in balance for 4,000 years are no longer present," said Trent University's polar expert Derek Mueller.

Canada's summer ice shelf losses now total 214 square kilometers (82.5 square miles), which is more than three times the area of Manhattan Island, the researchers said.

Extensive cracks in Ward Hunt, the largest remaining ice shelf, means it will continue to disintegrate in the coming years, said Luke Copland, director Ottawa University's cryospheric research lab.

Copland blamed "very warm temperatures" and "reduced sea ice" for the crumbling ice shelves.

The sea ice usually braced the shelves and without it, wind and waves more easily broke them apart, he explained.

The coast of Ellesmere Island has also warmed an average of two degrees (Celsius) in the last 50 years, he said. In winter, temperatures are now five degrees warmer, making it more difficult for ice lost in summer to recover in winter.

"We see that warming is concentrated in the winter," Copland said. "It's part of global warming. When we warm up the planet it gets concentrated close to he poles."