December 11, 2006 1:43 PM PST
Study: Most Arctic sea ice could disappear by 2040
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Sea ice shrinking rapidly
At AGU gathering, Marika Holland of the National Center for Atmospheric Research suggests that Arctic sea ice could be completely melted within 25 years.
"The ice is quite stable until 2025 and then, boom, it just goes," Holland said Monday during a presentation at the fall meeting of the American Geophysical Union taking place in San Francisco this week.
The primary underlying cause of the disappearance of the sea ice, she and other scientists said, is human-induced global warming. The Arctic has been rapidly heating up, so much so that the Arctic environment of today is substantially different from that of five years ago. By 2050, human-induced global warming could cause average temperatures in the region to rise by 3 degrees Celsius. That's the average among 12 studies that try to predict future changes in the Arctic caused by human activity.
Naturally induced global warming, however, will also play a role and serve as a tipping point to lead to the permanent degradation of the ice, Holland said. In other words, human-induced global warming gradually thins the ice, and then natural global warming kicks it over the edge.
The Arctic is already in trouble, said Mark Serreze, senior research scientist at the National Snow and Ice Data Center and a professor at the University of Colorado. Usually, the Arctic ice sheet shrinks until September, when it starts to grow again. At the end of November, there were 2 million fewer square kilometers of ice in the Arctic than normal, he said.
"We are no longer recovering well in autumn anymore," he said. "The effect of greenhouse gas-induced global warming is starting to rear its ugly head."
The economic, political and ecological effects could well be catastrophic, Serreze and others said at the conference. Greenland could begin to rapidly calve off glaciers in the North Atlantic. Ocean water levels around the world could rise 13 to 19 feet during the next several centuries. As the ice disappears and the Arctic Ocean warms, more of the microscopic plant life stays on the surface. Thus, bottom-feeders like crab and shellfish die off. Pollock and salmon, however, would do better. Sea lanes would open up above Russia and Canada.
Serreze joked that Russian colleagues tell him that global warming is good for them. "But on the balance, there are more losers than winners," he said.
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