Thursday, September 15, 2011

2011 Minimum Arctic Sea Ice Extent

Depending on your source, 2011 was either the 2nd lowest arctic sea ice extent, or the lowest. The title link is to the National Snow and Ice Data Center (NSIDC). Their satellite sensor, and the algorithms they use, show minimum sea ice extent for 2011 was 2nd to the all time minimum observed in 2007.

The University of Bremen uses a different sensor, on a different satellite, as well as different algorithms, and their analysis shows 2011 to be the lowest sea ice extent ever measured.

In a broader view, both these analyses show a consistent trend in loss of arctic sea ice since satellite measurements began in 1972. Current minimum sea ice extent is only 50% of what it was in 1972. Other data show that ice thickness is also decreasing.

Additional details from the University of Bremen study can be found in the press release link at their web site. From this press release: "Climate models show rather that the reduction is related to the man-made global warming which, due to the ice albedo effect, is particularly pronounced in the Arctic: an ice area melted by a small temperature increase will then as open water have a much darker surface, absorb more solar radiation than before, which causes additional heating.......

The ice maps of the University of Bremen show also that in this year, the Northwest and Northeast passages are ice free simultaneously (Figure 2). This had happed for the first time in 2008, and in 2009 the German shipping company Beluga has traveled it commercially for the first time."




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