Arctic Shelves Have Halved In 6 Years

Canada’s Arctic ice shelves, formations that date back thousands of years, have been almost halved in size over the last six years, Canadian researchers said on Tuesday.

Researchers at Carleton University in Ottawa, who regularly analyze satellite images from the region, also found that a major portion of the ice shelves split in half this summer and other pieces covering an area roughly one and a half times that of Manhattan have broken off since the end of July.

Consistently higher temperatures in Canada’s Arctic, the researchers said, were the main cause of the dramatic decline.

“It’s fascinating to bear witness to this as a scientist but it also saddens me as a general citizen of the planet to see this happen,” said Derek Mueller, a professor at the university’s school of geography and environmental studies. “We’ve seen this on timescale of six years yet these ice shelves are thought to have been in place for thousands of years.”

The ice shelves are as large as they are ancient. Professor Mueller said that they are commonly as thick as a 10 story building is high, although they are sometime more than twice that size.

While the increased Arctic temperatures decay the ice shelves by creating cracks, they are also undermining the formations by exposing them directly to the waters of the Arctic Ocean. Historically, Professor Mueller said, the shelves were buffered from the sea by a barrier of pack ice the age of which is measured in decades. Now that pack ice has disappeared in many areas, exposing the ice shelf to direct contact with waves causing destructive flexing and heaving of the ice.

In addition to reducing the only environment the  supports some kinds of microbial life, the breaking apart of the ice shelves may hinder plans to exploit the warming Arctic as a shipping route and an offshore oil drilling basin.

While the eastern Canadian Arctic has long been plagued by icebergs that separated from glaciers, Professor Mueller said that had not been the case in the west. The pieces now breaking off the ice shelves, however, are now bringing massive icebergs in the Western Arctic Ocean as well.

“This is an area of the world where temperatures are rising very rapidly and the ice shelves are responding,” Professor Mueller said

http://green.blogs.nytimes.com/2011/09/28/arctic-shelves-have-lost-half-their-size-in-six-years/

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