Vast Arctic ice shelf breaks free

A 25-square-mile shelf of floating ice that jutted into the Arctic Ocean for 3,000 years from Canada's northernmost shore broke away abruptly in the summer of 2005, apparently freed by sharply warming temperatures and jostling wind and waves, scientists announced on Dec. 28. The Ayles Ice Shelf, larger in area than Manhattan, broke clear 16 months ago from the coast of Ellesmere Island, about 500 miles south of the North Pole in the Canadian Arctic. Some scientists say it is the largest event of its kind in Canada in 30 years and that climate change was a major factor. The break-up of the ice was first noticed by Laurie Weir of the Canadian Ice Service as she examined satellite images taken of Ellesmere. Weir notified Dr. Luke Copland, the director of the University of Ottawa's Laboratory for Cryospheric Research, who initiated an effort to find out what had happened. Using a combination of US and Canadian satellite imagery and seismic records, Copland discovered that the separation of the ice shelf occurred in less than an hour, on the afternoon of Aug. 13, 2005. The ice shelf, which floats on water but is connected to land, was one of the few remnants of a broad expanse of floating shelves of ice that once protruded along much of the Ellesmere coast. Before the breakup the Canadian Arctic had six ice shelves. "Now there are five," Copland said. Ninety percent of the 3,900 square miles of ice shelves that existed in 1906 when the Arctic explorer Robert Peary first surveyed the region are gone, said Copland. In a paper summarizing the event but not yet published, Copland and other researchers said that the transformation of the Ayles ice from a shorebound shelf to a drifting ice island appeared to be a result of unusual Arctic warmth in 2005 on top of a longer-term warming trend. He said that it was premature to attribute the breakaway to human-caused climate change, although he said that it was a clear sign the warming in the region was producing significant and abrupt changes, and more were likely in coming years. "The quick pace of these changes right now is what stands out," he said. There have already been several disturbing indications this year that the Arctic ice is melting at a much faster rate than expected. In September, two NASA reports showed a great surge in the disappearance of the winter sea ice over the past two years, with an area the size of Turkey disappearing in 12 months. Professor Warwick Vincent, who studies Arctic conditions at Laval University in Quebec City, 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." Vincent said that the event was "consistent with climate change" and added, "We aren't able to connect all of the dots... but unusually warm temperatures definitely played a major role." The summer of 2005 was the warmest recorded on Ellesmere Island since 1960, with temperatures about 3.8°F above average. Due to the warm temperatures, 2005 set a record for the lowest amount of Arctic Ocean sea ice ever recorded. Sea ice normally buffers the ice shelf from ocean movement. But with little ice and strong offshore winds, waves were able to batter the ice shelf, weakening it. And the ice shelf breakup wasn't the only geologic disturbance on Ellesmere Island that summer. Antoni Lewkowicz, a geography professor at the University of Ottawa, happened to be on the island when the ice shelf separated, although he was unaware of the event at the time. For nearly 20 years Lewkowicz has been studying landslides triggered by melting permafrost. The overall warm summer thawed out the island significantly, he said, and a week of strong sun at the end of July set off massive numbers of landslides. "You need a blast of heat," he said. "And that's what happened–a week of clear weather and warm temperatures, which triggered a whole bunch of landslides literally all around us." In one 3.5-square-mile tract he counted 50 landslides during the warming period. "So there were reactions to that warm period on the land as well," he said. The broken ice shelf and Lewkowicz's landslides are important indicators of global climate change and its effects on the polar ice caps. In the past five years, several ice shelves along the fringes of the Antarctic peninsula have started to become unstable or break up. The most spectacular was the 2002 collapse of the Larsen B ice shelf, the size of Luxembourg. While neither melting ice shelves nor sea ice contribute to rising sea levels, ice shelves do play an important role in stabilizing land ice, the melting of which would significantly impact sea levels.