Scientists have announced the maximum 2011 Arctic sea ice extent occurred on March 7, apparently the smallest winter extent ever. The orange line shows the median extent for 1970-2000. (Source: NSIDC)
The Arctic ice cap is shrinking, year by year, in a trend that many scientists say will lead to a complete vanishing of the summer Arctic ice cap by the year 2050, if not sooner. This winter season, on March 7, the ice layer covering the Arctic likely reached its maximum extent, tying the 2006 winter season for the smallest extent ever.
Arctic sea ice likely reached its maximum extent for the year, at 14.64 million square kilometers (5.65 million square miles). This was 1.2 million square kilometers (463,000 square miles) below the 1979 to 2000 average of 15.86 million square kilometers (6.12 million square miles), and equal (within 0.1%) to 2006 for the lowest maximum extent in the satellite record.
Arctic sea ice extent appeared to reach its maximum extent for the year on March 7, marking the beginning of the melt season. As of March 22, ice extent has declined for five straight days; however, there is still a chance that the ice extent could expand again.
In the beginning of April, the National Snow and Ice Data Center (NSIDC) will issue a formal announcement with a full analysis of the 2010 to 2011 winter season.
Sea ice extent in February and March tends to be quite variable, because ice near the edge is thin and often quite dispersed. The thin ice is highly sensitive to weather, moving or melting quickly in response to changing winds and temperatures, and it often fluctuates near the maximum extent for several days or weeks, as it has done this year.
Since the start of the satellite record in 1979, the maximum Arctic sea ice extent has occurred as early as February 18 and as late as March 31, with an average date of March 6.
While it still remains to be seen what effect this will have on the state of the Arctic ice cap in the summer of 2011, the reduction of the ice layer revealing open water is sure to have a significant head start with this small extent. While the smallest Arctic sea ice extent in history did not occur in the summer of 2006, it did occur in the summer of 2007. This gives a good indication that this evolutionary phenomena is amassed over years and not necessarily in immediate successive terms.
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(Source: National Snow and Ice Data Center, University of Colorado at Boulder)
