Unbelievable is probably an understatement - I don't think anyone was predicting this. Also troubling is the asymmetry of the icecap, as if something unique is happening this year in the western half of the Arctic.




The temp anomalies have been stronger in the west, but I suspect something may also be going on with the ocean currents. To quote from the NSIDC web page

Quote:

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Impacts of ocean circulation

In the August 22 report, we explained that another part of the 2007 story is "memory" of the sea ice to changes that have been unfolding over the past few decades. Our focus there was on the apparent transition to younger, thinner ice since the late 1970. As discussed, factors contributing to this thinning involve a general rise in air temperatures, and changing winds that have transported fairly thick ice out of the Arctic Ocean into the North Atlantic. An issue that we haven't addressed, yet, is changes in ocean circulation.

One prominent researcher, Igor Polyakov at the University of Fairbanks, Alaska, points out that pulses of unusually warm water have been entering the Arctic Ocean from the Atlantic, which several years later are seen in the ocean north of Siberia. These pulses of water are helping to heat the upper Arctic Ocean, contributing to summer ice melt and helping to reduce winter ice growth. Another scientist, Koji Shimada of the Japan Agency for Marine–Earth Science and Technology, reports evidence of changes in ocean circulation in the Pacific side of the Arctic Ocean. Through a complex interaction with declining sea ice, warm water entering the Arctic Ocean through Bering Strait in summer is being shunted from the Alaskan coast into the Arctic Ocean, where it fosters further ice loss.

Many questions still remain to be answered, but these changes in ocean circulation may be important keys for understanding the observed loss of Arctic sea ice.

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