Wednesday, August 19, 2009

Arctic sea ice decline slowed in August

The National Snow and Ice Data Center reported in its mid-monthly Arctic Sea Ice News that the rate of melting of Arctic sea ice declined in the first half of August. The report says:

During the first half of August, Arctic ice extent declined more slowly than during the same period in 2007 and 2008. The slower decline is primarily due to a recent atmospheric circulation pattern, which transported ice toward the Siberian coast and discouraged export of ice out of the Arctic Ocean. It is now unlikely that 2009 will see a record low extent, but the minimum summer ice extent will still be much lower than the 1979 to 2000 average.

The chart of Arctic Sea Ice Extent show that 20007 was far below the 1979-2000 average, 2008 was not quite as bad as 2007, and so far 2009 is not as bad as 2008 at this point in the season. 2009 is on track to still be significnantly worse than the long-term average, but I would simply point out that we haven't set a new record for two years now. There is about a month to go before the melting reverses.

Technically, the center is not measuring "melting" per se, but is analyzing satellite images to estimate the area of the sea surface that is at least 15% covered by sea ice. This roughly translates into melting, but not in a necessarily precise manner.

-- Jack Krupansky


At 8:28 PM , Blogger Lee Devlin said...

Jack, I have heard that the sea ice in the southern hemisphere is increasing. Any news on that? Also, if sea ice is floating, does melting it cause much in the way of a sea level rise? I mean, it's already displacing its weight in water, right? Why all the concern if it melts? I do understand that it reflects more than sea water because of its color, but the amount of sun it gets is much less because of the angle of incidence too.


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