During April, Arctic sea ice extent declined at a steady pace, remaining just below the 1979 to 2000 average. Ice extent for April 2010 was the largest for that month in the past decade. At the same time, changing wind patterns have caused older, thicker ice to move south along Greenland’s east coast, where it will likely melt during the summer. Temperatures in the Arctic remained above average.
Overview of conditions
Arctic sea ice extent averaged 14.69 million square kilometers (5.67 square miles) for the month of April, just 310,000 square kilometers (120,000 square miles) below the 1979 to 2000 average. The rate of ice extent decline for the month was also close to average, at 41,000 kilometers (16,000 square miles) per day. As a result, April 2010 fell well within one standard deviation of the mean for the month, and posted the highest April extent since 2001.
Ice extent remained slightly above average in the Bering Sea and Sea of Okhotsk, and slightly below average in the Barents Sea north of Scandinavia, and in Baffin Bay, where ice extent remained below average all winter.
Conditions in context
The very late maximum ice extent, on March 31, means that the melt season started almost a month later later than normal.
As we noted in last month's post, the late growth in ice extent came largely from expansion in the southernmost Bering Sea, Barents Sea, and Sea of Okhotsk. These areas remained cool, with northeasterly and northwesterly winds, keeping the overall ice extent close to the average for the month of April.
April 2010 compared to past years
Average ice extent for April 2010 was 820,000 square kilometers (317,000 square miles) greater than the record low for April, observed in 2007, and 310,000 square kilometers (120,000 square miles) below the average extent for the month. The linear rate of decline for April over the 1979 to 2010 period is now 2.6% per decade.
EDIT
http://nsidc.org/arcticseaicenews/index.html