After reaching near-average levels in late April, sea ice extent declined rapidly during the early part of May. The rest of the month saw a slower rate of decline. Ice extent in the Bering Sea remained above average throughout the month.
Arctic sea ice extent for May 2012 averaged 13.13 million square kilometers (5.07 million square miles). This was 480,000 square kilometers (185,000 square miles) below the 1979 to 2000 average extent. This May’s extent was similar to the May 2008 – 2010 extent, but it was higher than May 2011. May ice extent was 550,000 square kilometers (212,000 square miles) above the record low for the month, which happened in the year 2004.
For May, the Arctic as a whole lost 1.62 million square kilometers (625,000 square miles) of ice, which was 180,000 square kilometers (69,500 square miles) more than the 1979 to 2000 average. The average daily rate of ice loss was 52,000 square kilometers (20,000 square miles) per day, which was slightly faster than the long-term average of 46,000 square kilometers (18,000 square miles) per day.
However, the rate of ice loss for the month was composed of two distinct periods: a rapid loss of ice during the first part of the month, followed by near-average rates during the latter part of the month.
Arctic sea ice extent for May 2012 was below average for the month, compared to the satellite record from 1979 to 2000. However, the ice extent this May was not as low as it has been in some recent years. Including the year 2012, the linear rate of decline for May ice extent over the satellite record is 2.3% per decade.