Friday, October 7, 2011

2011 Arctic Sea Ice Minimum

Well, I had a bet going that we'd break the record September Arctic sea ice minimum set in 2007 this year.  I didn't bet any money, just the honor of being right.  I lost, which is probably for the best, considering the stability of the climate system.  We had extensive sea ice loss early on when I placed the bet, but recovery happened a bit early this year, so we ended up with the second lowest recorded September sea ice extent.  The National Snow and Ice Data Center (NSIDC) is just next door in Boulder, CO where two of my old PhD committee members run the place.  Read more on this year's sea ice here.

Something to note about sea ice loss is that, because it is floating ice, it does not contribute to sea level rise.  It does, however, play a huge role in the ice-albedo positive feedback loop.  Less ice during seasons with sunlight allow the absorptive surface of the ocean to take in more sunlight, warming the system, causing more ice loss, more absorption of sunlight, and higher temperatures, and so on.  The warmer the Arctic, the more likely we'll get increased sea level rise from sea ice's big brother, the Greenland Ice Sheet.  This is a huge concern!

A few figures from NSIDC: 
Can you see how I was fooled?  Look at the cyan line for 2011, it was dropping pretty fast!

Monthly September ice extent for 1979 to 2011 shows a decline of 12.0% per decade.

Arctic sea ice extent for September 2011 was 4.61 million square kilometers (1.78 million square miles). The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole.
Note that the Northwest Passage and the Northern Sea Route were both open this year.