EDMONTON (Alberta), July 30: Officials have said that a big chunk of ice broke off Canada’s largest remaining ice shelf last week.

Trent University researcher Derek Mueller said it wouldn’t surprise him if even more ice broke off this summer from the Ward Hunt Ice Shelf, a vast frozen plain off the north coast of Ellesmere Island in Canada’s far north.

In a development consistent with climate change theories, the enormous icy plain broke free sometime last week and began slowly drifting into the Arctic Ocean. The piece had been a part of the shelf for 3,000 years.

A crack in the shelf was first spotted in 2002. Last spring, a patrol of Canadian Rangers found that the weakness had spread into an extensive network of cracks, some 40 metres wide and 18 kilometres long. The crack-riddled section of ice was like a jigsaw puzzle, with the pieces held in place only by each other.

Formed by accumulating snow and freezing melt-water, ice shelves are large platforms of thick, ancient sea ice that float on the ocean’s surface. Ellesmere Island was once entirely ringed by a single enormous ice shelf that broke up in the early 1900s.

At 440 square kilometres in size and 40 metres thick, the Ward Hunt shelf is the largest of those remnants --- even bigger than the Antarctic shelf that collapsed earlier this year and seven times the size of the Ayles Ice Shelf chunk that broke off in 2005 from Ellesmere’s western coast.

Despite a period of stability in the 1980s, the Ward Hunt shelf and its characteristic corrugated surface has been steadily declining since the 1930s, said Mueller. Its southern edge has lost 18 square kilometres over the last six years.

Mueller is careful not to blame the Ward Hunt break-up specifically on climate change, but said it is consistent with the theory. The current Arctic climate certainly isn’t reinforcing ice shelves.

“We’re in a different climate now,” he said. “It’s not conducive to re-growing them. It’s a one-way process.”—AP