Giant Ice Shelf Breaks Free in Arctic; Climate Change Cited as Major Factor
Saturday, December 30, 2006
TORONTO, Dec. 29 -- A giant ice shelf has snapped free from an island south of the North Pole, scientists have said, citing climate change as a "major" reason for the event.
The Ayles Ice Shelf -- all 41 square miles of it -- broke clear 16 months ago from the coast of Ellesmere Island, about 500 miles south of the North Pole in the Canadian Arctic.
Scientists said Thursday that they had discovered the event by using satellite imagery. Within one hour of breaking free, the shelf had formed as a new ice island, leaving a trail of icy boulders floating in its wake.
Warwick Vincent of Laval University in Quebec City, who studies Arctic conditions, said he traveled to the newly formed ice island and couldn't believe what he saw.
"This is a dramatic and disturbing event. It shows that we are losing remarkable features of the Canadian North that have been in place for many thousands of years," Vincent said. "We are crossing climate thresholds, and these may signal the onset of accelerated change ahead."
The ice shelf was one of six major shelves remaining in Canada's Arctic. Packed with ice that is more than 3,000 years old, they float on the sea but are connected to land.
Some scientists say that the shelf's collapse is the largest event of its kind in Canada in 30 years and that climate change was a major factor.
"It is consistent with climate change," Vincent said, adding that the remaining ice shelves are 90 percent smaller than when they were first discovered in 1906. "We aren't able to connect all of the dots . . . but unusually warm temperatures definitely played a major role."
Laurie Weir, who monitors ice conditions for the Canadian Ice Service, was poring over satellite images in 2005 when she noticed that the shelf had split and separated. Weir notified Luke Copland, head of the new global ice lab at the University of Ottawa, who initiated an effort to find out what happened.
Using U.S. and Canadian satellite images, as well as seismic data -- the event registered on earthquake monitors 155 miles away -- Copland discovered that the ice shelf collapsed in the early afternoon of Aug. 13, 2005.
Copland said the speed with which climate change has affected the ice shelves has surprised scientists.
"Even 10 years ago, scientists assumed that when global warming changes occur that it would happen gradually, so that perhaps we expected these ice shelves just to melt away quite slowly," he said.