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Friday, November 7, 2008

Arctic Summer Could be Ice-Free by 2105


If the current warming trends continue in the Arctic, the region may have ice-free summers within 100 years, a new report concludes.


The Arctic hasn't been without ice for a million years. But documented melting is accelerating and scientists don't know of any natural way to slow it.


Scientists expect 2005 to be the warmest year on record, globally.


"What really makes the Arctic different from the rest of the non-polar world is the permanent ice in the ground, in the ocean, and on land," said Jonathan Overpeck, chair of the National Science Foundation's Arctic System Science Committee. "We see all of that ice melting already, and we envision that it will melt back much more dramatically in the future, as we move towards this more permanent ice-free state."


The melting of Arctic glaciers and ice sheets is bad news for the various animals – polar bears, seals, walruses, and orca whales to name a few – that call this region their home. As these animals are affected, so will be the native tribes that still live in the area and hunt these animals.


But the effects will reach much farther than that – the melted ice will cause sea levels to rise worldwide, flooding the coastal areas where many of the world's people live. Melting ice has already drastically impacted the indigenous people and animals of parts of Alaska, Canada, Greenland, Russia, and Scandinavia.

And melting ice isn't the only problem.

Overpeck echoed other scientists in warning that permafrost – the permanently frozen layer of soil under most of the Arctic landmass – could also melt and maybe disappear altogether in some areas. This thawing could release more greenhouse gases – trapped in the permafrost for thousands of years – which would add to the warming problem.


Other studies have shown the permafrost is already dwindling in many Northern Hemisphere locations.


The new report concludes that several environmental factors could coalesce to lead to this no-ice condition. Interactions between sea and land ice, North Atlantic Ocean circulation, and precipitation and evaporation in the region create a dangerous cycle of warming conditions.


For example, the white surface of the sea ice reflects radiation from the Sun, which melts the ice. With less ice to reflect radiation, the dark ocean absorbs more and warms up, which causes more ice to melt.


The report was the result of a weeklong meeting of climate experts and other scientists.


"I think probably the biggest surprise of the meeting was that no one could envision any interaction between the components that would act naturally to stop the trajectory to the new system," said Overpeck.


Scientists have identified a feedback loop that could slow the changes, but they do not know of any way to put a halt to the melting ice.


This report is is published today in in Eos, the weekly newspaper of the American
Geophysical Union.

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