This post comes about a week earlier than my end-of-the-month version because it looks like the minimum areal extent of arctic sea ice has likely been reached for 2009. Allowing for the possibility for the final, official number to come out later this year, the minimum extent should come in near 5.10 million sq. km. (1.97 million sq.mi.). This places 2009′s extent as the third-lowest on record, behind the record low extent in 2007 and last year’s 2nd place finish. The difference between 2008 and 2009 is about 580,000 sq. km. (220,000 sq. mi.) and this year’s minimum is 970,000 sq. km. (370,000 sq. mi.) above the record low set in 2007.
In contrast to longer-term conditions, the 2009 minimum is 1.61 million sq. km. (620,000 sq. mi.) below the 1979 to 2000 average minimum and 1.28 million sq. km. (490,000 sq. mi.) below the thirty-year 1979 to 2008 average minimum. Another way of describing this year’s minimum is it also fell well below the 2nd standard deviation below the median, just as it did in 2007 and 2008. Does this mean the danger to the arctic ice sheet is over? After all, 2007 saw the minimum and the extent has only increased since then. The answer is no. As I wrote in my last two monthly posts, the low extent this year instead indicates that a new range of conditions appear to be “normal” for the Arctic. The areal extent that was observed in the 20th century is less and less likely to be observed in the 21st century.
Keep in mind that these areal minimums (3 of them in a row) have occurred when solar input has been at an abnormally long minimum and during a moderate-strength La Nina event. Those La Nina conditions have since changed to El Nino conditions, which continue to strengthen this fall. After the maximum intensity, expected sometime this winter, 2010 is pretty likely to see record high global average temperatures. We already know that the Arctic has seen the fastest rise in temperatures than anywhere else on the globe so far – how will even more warming on top of the human warming affect the ice and ocean next year? Does anyone seriously think conditions will significantly improve? How about when the sun’s activity increases? Things might oscillate around and one year or another might exhibit slightly different characteristics, but things have fundamentally changed. Unless and until we get our GHG emissions under serious control, the Arctic will be a very different place in the 21st century than it was in the 20th.
An extensive report on the State of the Climate for 2008 by the American Meteorological Society has been issued. I’ve found a number of interesting items I want to write about already with more to discover, I’m sure. Look for upcoming posts about the 2008 data and tie-ins to even more recent results like this one.
Cross-posted at SquareState.