Warming threatens Arctic glaciers

MONTREAL, May 25, 2007 (AFP). Warming in Canada's far north is melting glaciers that threaten to split into massive chunks and float away, a Canadian researcher told AFP Friday, after tagging an iceberg as big as Manhattan.

Geologist Luke Copland of the University of Ottawa, and his colleague Derek Mueller of the University of Alaska Fairbanks, visited Ayles Ice Island this week to install beacons to follow its movements through the Arctic Ocean.

"On Monday, we landed on the ice island and (installed) a satellite tracking beacon, so we can track where the ice island (goes), and a temperature censor, which every hour will record the temperature," Copland told AFP.

The 16-by-five-kilometer (10-by-three-mile) slab of ice had split from Canada's Ellesmere Island close to Greenland in August 2005, but was only identified late last year. The break was so violent that it caused tremors that were detected by Canadian seismographs 250 kilometers away, but at the time no one was able to pinpoint what had happened.

Copland, who reconstructed the chain of events by piecing together data from the seismic readings and satellite images, had said when the discovery was announced in December, the rupture was the "biggest in 25 years" in the Arctic. After visiting the island for the first time this week, he said: "You really need to see it. Normally Arctic sea ice has a very, very rough surface ... But this piece is just so big, it's flat and smooth."

According to the Canadian Ice Service, relying on satellite images, the island has traveled less than 100 kilometers to the south since its rupture, but has been stuck in an ice field in recent months.

"It's really amazing how fast they move, if there's not much sea ice (around it)," Copland said.

The satellite tags installed on the island will track its movements as it drifts toward Alaska, where it could pose a danger to offshore oil rigs.

"We know roughly that it will drift to the west and that it's driven by the ocean current, but beyond that we don't know how long will it take to reach Alaska. It might take five years, 10 years, we don't know exactly," Copland said.

The Earth's polar regions have been most affected by warming, believed to be caused by greenhouse gas emissions, with temperatures in the Arctic rising twice as fast as elsewhere over the past century.

According to the UN's Intergovernmental Panel on Climate Change, Arctic ice cover and thickness is likely to be substantially reduced by 2100. Almost 90 percent of the ice cover in the region had been lost since it was first discovered during a polar expedition in 1906, Copland said.

Due to warming, he now fears that five glaciers clinging to Ellesmere Island will not rejuvenate themselves, as they once did, and soon crumble into the ocean.

"One of them called the Ward Hunt Ice Shelf, which is the largest on Ellesmere Island, had broken in half in 2002," Copeland said. "There is a big crack at the center. And another (glacier) lost some area in 2005."

"It does not look particularly good for them for the future," he said. Ice fields are also threatened by warming, Copeland explained, pointing to various predictions of floating sea ice disappearing from the Arctic Ocean by 2040 or 2050.

"Normally, the sea ice pushes up against the ice shelves and really protects the front of the ice shelves. If there is no sea ice, then the ocean waves can get in cracks much more easily," and make the glaciers brittle.

The two researchers, accompanied by a team of BBC television reporters, also took measurements of the ice thickness near Ayles Glacier, which spawned the ice island, hoping to better understand the phenomena.