Wednesday, March 27, 2013

Arctic Sea Ice Maximum Sixth Lowest In Satellite Era

Arctic sea ice, which last September reached a record low, has likely set its winter maximum for areal extent.  The final number, which appears to be 15.13 million square kilometers (5.84 million square miles), is the sixth lowest number in the satellite era, which goes back to 1979.  While an impressive recovery compared to the record lows we saw earlier in the winter, it still wasn't enough to get back to "normal" as you can see the areas of blue inside the pink "climo" line.

The normal maximum is 15.86 million square kilometers (6.12 million square miles), which means our maximum is 733,000 square kilometers below average, about the size of Texas.

That said, the ice recovery was a record in terms of ice growth over the seasonal minimum, with ice growth in the Arctic totaling 11.72 million square kilometers, which is 2.63 million square kilometers higher than the average.  Much of this ice, first year sea ice, is more prone to melting due to it being thinner than sea ice that has been around in the Arctic longer. Thinner ice is more prone to melting during the Arctic summer so it's possible we may see a rather marked dropoff in the coming months.  The average sea ice volume in the winter has dropped nine percent from 2003 to 2012, due in part to summer melting and the winter recovery ice being newer and thinner.

Comparing normal to reality, the areas with the largest dropoff to average in sea ice were in the North Atlantic -- particularly off of the east coast of Canada, as well as to the north of Scandinavia.  The Bering Sea produced more sea ice this winter, buoyed in part by a very cold November and early December over Alaska to help increase ice production over that area.