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Huge chunks of Arctic island breaking off. OTTAWA -- Giant sheets of ice totalling almost 20 square kilometres broke off an ice shelf in the Canadian Arctic last week -- and more could follow, scientists say.
Temperatures in large parts of the Arctic have risen far faster than the global average in recent decades, a development that experts say is linked to global warming.
The ice broke away from the shelf on Ward Hunt Island, a small island just off giant Ellesmere Island.
It was the largest fracture of its kind since the nearby Ayles ice shelf -- 65 sq. km -- broke away in 2005.
Scientists had already identified deep cracks in the Ward Hunt shelf, which is about 400 sq. km and is one of five along Ellesmere Island.
"Because the breakoff occurred between two large parallel cracks, they're thinking more could go this summer before the freeze sets in,'' said Trudy Wohlleben of the Canadian Ice Service.
"More could be a piece as large as the Ayles ice shelf.''
Ellesmere Island was once home to an enormous ice shelf totalling about 9,000 sq. km. All that is left of it are five much smaller shelves covering about 1,000 sq. km.
"The breakoff is consistent with other changes we've seen in the area, such as the reduction in the amount of sea ice, the retreat of the glaciers and the breakup of other ice shelves,'' Wohlleben said.
She said a strong wind from the south likely initiated the breakoff.
Warwick Vincent, director of the Centre for Northern Studies at Laval University in Quebec, said most of the rest of the Ward Hunt ice shelf is now vulnerable.
"It underscores the fact that each year we're now crossing new thresholds in environmental change in the High Arctic, and of course our concern in the longer term is that these may signal the onset of serious change at all latitudes,'' he said.
Derek Mueller, an Arctic ice-shelf specialist at Trent University in Ontario, is concerned by the rapidity of changes in the High Arctic.
"It's a bit of a wake-up call for those people who aren't yet affected by climate change -- that there are places on Earth that are, and the same could be true for them, if you fast-forward a decade or two, or three. Whatever has kept this ice shelf in balance for 3,000 years is no longer keeping it in balance,'' he said.
Wohlleben said the ice shelves held ecosystems that had yet to be studied and could not be replaced, because they took so long to form.
"Once they've broken off, they're gone,'' she said.
Reuters
Published: Wednesday, July 30, 2008
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