Arctic Summers Ice Free by 2040, Study Predicts

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Winter ice will thin from about 12 feet (3.7 meters) to 3 feet (1 meter) thick.

Tremblay explains that the Arctic sea ice is like a giant mirror. It reflects the sun's energy back into space and prevents much of it from being absorbed by the ocean.

But as warmer average temperatures melt the ice, the mirror shrinks. A smaller mirror means that the ocean absorbs more of the sun's energy, which creates further warming.

This warming causes more ice to shrink, which causes more heat absorption.

"It goes into a positive feedback loop—a very efficient way of getting rid of the ice cover," Tremblay said.

In addition, climate models suggest that global warming will alter ocean circulation patterns and drive warmer Atlantic waters into the Arctic.

"That is a positive feedback as well," he added. "It enhances the melting of the ice."

Dire Consequences

According to Tremblay, as the ice thins due to climate warming, a particularly warm summer or a pulse of warm water from a modified circulation pattern might be the tipping point.

"For us to say it could happen by 2020 or 2030 is not unrealistic," he said. "We are already seeing very strong signs in the rate of sea ice change."

Loss of Arctic sea ice would likely take a lethal toll on animals such as polar bears that rely on the ice as a hunting platform. (Related news: "Polar Bears Suffering as Arctic Summers Come Earlier, Study Finds" [September 21, 2006].)

Local indigenous people would also be unable to fish from the ice, forcing them to adapt.

"That's going to be a big strain on their mode of living," he said.

What's more, the melting ice could open up new shipping lanes through the Arctic and spark a race to exploit newly exposed resources.

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