Huge sections of northern ice shelf lost in August, researchers report
by MATTHEW CAMPBELL

Massive pieces of Canada's northern ice shelf broke away in early August, a team of researchers reported yesterday. The 50-square-kilometre Markham shelf, located on the northern coast of Ellesmere Island, is now floating free in the Arctic ocean along with a larger portion of the Serson shelf.

Meanwhile, remnants of the Ward Hunt ice shelf, which attracted international publicity when it collapsed in July, continue to float away from the Ellesmere shore.

Collapses like those this summer worry scientists since shelf ice, unlike more ephemeral sea ice, can be as much as 4,500 years old and 40 metres thick.

Dr. Derek Mueller, the Roberta Bondar Fellow in Northern and Polar Studies at Trent University in Peterborough, Ont., said recent losses of shelf ice - totalling 214 square kilometres this summer in the Canadian north - are almost certainly the result of global warming.

"You just can't have ice shelves in a warm climate," Dr. Mueller said.

"You can't link any one event to climate change, but we can certainly link patterns."

Satellite photographs show that the extent of sea ice around Ellesmere Island has also been significantly reduced. Where once Arctic waters were frozen right up to the edge of the island, there is now a substantial expanse of open water.

The news that large pieces of shelf ice have been lost comes just after Prime Minister Stephen Harper's tour of the high Arctic, where he has promised to expand Canada's military presence and boost natural resource exploration.

But Dr. Mueller said that would-be Arctic explorers should tread carefully, if only for their own safety.

"Until it melts," he said, "floating ice is a hazard to navigation."