Arctic Ice Melt Is Setting Stage for Severe Winters

http://www.sciencedaily.com/releases/2012/06/120606132420.htm

ScienceDaily (June 6, 2012) — The dramatic melt-off of Arctic sea ice due to climate change is hitting closer to home than millions of Americans might think.

That's because melting Arctic sea ice can trigger a domino effect leading to increased odds of severe winter weather outbreaks in the Northern Hemisphere's middle latitudes -- think the "Snowmageddon" storm that hamstrung Washington, D.C., during February 2010.

Cornell's Charles H. Greene, professor of earth and atmospheric sciences, and Bruce C. Monger, senior research associate in the same department, detail this phenomenon in a paper published in the June issue of the journal Oceanography.

"Everyone thinks of Arctic climate change as this remote phenomenon that has little effect on our everyday lives," Greene said. "But what goes on in the Arctic remotely forces our weather patterns here."

A warmer Earth increases the melting of sea ice during summer, exposing darker ocean water to incoming sunlight. This causes increased absorption of solar radiation and excess summertime heating of the ocean -- further accelerating the ice melt. The excess heat is released to the atmosphere, especially during the autumn, decreasing the temperature and atmospheric pressure gradients between the Arctic and middle latitudes.

A diminished latitudinal pressure gradient is associated with a weakening of the winds associated with the polar vortex and jet stream. Since the polar vortex normally retains the cold Arctic air masses up above the Arctic Circle, its weakening allows the cold air to invade lower latitudes.

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