In 2007, polar ice cap vanished at record clip

By Amanda Beck

SAN FRANCISCO (Reuters) - Arctic ice at the North Pole melted at a record rate in the summer of 2007, the latest sign that climate change has accelerated in recent years, climate scientists said on Wednesday.

"In 2007, we had off-the-charts warming," Michael Steele, an oceanographer at the University of Washington, said at the 2007 meeting of the American Geophysical Union, where 15,000 researchers have gathered to discuss earthquakes, water resources, and climate change.

It was an ominous summer for the Arctic region, where for the first time in recorded history, ships sailed across the Arctic Ocean in water that had been part of the polar ice cap, said Donald Perovich of the U.S. Army Cold Regions Research and Engineering Laboratory in New Hampshire.

While in the summer of 1980 the North Pole was covered by an ice sheet about the size of the continental United States, this summer the ice would not have covered the states west of the Mississippi River, he added.

"It's a tremendous decrease, but of course, the mystery is how did it happen?" Perovich said.

Scientists said two principal factors are accelerating the vanishing of the polar ice pack, which helps cool the Earth by reflecting the sun's rays back into the atmosphere.

As temperatures in the Pacific and Atlantic Oceans rise, warmer water moves into the Arctic Ocean. This helps melt the polar ice cap, which this year floated in water about 6.3 degrees Fahrenheit (3.5 degrees Celsius) warmer than its historical mean, Steele said.

"Water that is now circulating just 200 meters below the main ice pack is now significantly warmer than it was just five years ago," said John Walsh of the University of Alaska, Fairbanks.