Wednesday, March 03, 2010

Arctic Sea Ice has increased by 19% since 2007

According to the World Meteorological Organization, Arctic sea ice has increased by 19 percent since its minimum in 2007.

2009 was indeed still 27.4 percent below the 1979 to 2000 average of 7.03 million square kilometers, but the gap has gotten much smaller than the 39.2 percent in 2007. Who is to say whether or not the time-frame around 1979 was or was not the anomaly. Averages must be taken over vast time frames.

Year . . . . Average Minimum Extent (million square kilometers)
2007 . . . . 4.28
2008 . . . . 4.67
2009 . . . . 5.10

Al Gore claimed during the Copenhagen Climate Summit that "These figures are fresh. This is the volume metric measure of the ice and some of the models suggest to Dr Maslowski that there is a 75 per cent chance that the entire north polar icea cap, during the summer months, could be completely ice-free within five to seven years." Gore apparently didn't have the last two years of data with his "fresh" figures. For the AP version of the story, which doesn't question his claims at all, see here. AP did not do their fact checking very well.

Al Gore's claim was likely obtained by extrapolating the drop of 2006 to 2007 into present day, and assuming that the rate of drop would continue. It did not. The fact that the amount of ice increased after 2007 would presumably bring some caution to the discussion.


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