Arctic sea ice starts its big melt: data centre
Arctic sea ice cover reached at its maximum for 2012-13 on March 15
On March 15, Arctic sea ice extent appears to have reached its annual maximum extent, the National Snow and Ice Data Center said March 25.
That date marked the beginning of the yearly sea ice melt season, with the 2012-13 maximum extent of about 15 million square kilometres coming in as the sixth lowest in the satellite record.
The maximum extent was 733,000 sq. km. below the 1979 to 2000 average of 15.86 million sq. km.
And it occurred five days later than the 1979 to 2000 average date of March 10.
The NSIDC said the date of the maximum Arctic ice extent has varied considerably over the years.
The earliest maximum in the satellite record occurred as early as Feb. 24 in 1996 and as late as April 2 in 2010. The lowest maximum extent occurred in 2011.
But the trend is heading in a downward direction: the ten lowest maximums in the satellite record of more than 30 years occurred from 2004 to 2013.
Over the 2012 to 2013 winter season, Arctic sea ice extent did grow by a record 11.72 million sq. km.
The record growth was a result of the record low minimum last September, which left a greater extent of ocean surface uncovered by ice to re-freeze this winter, the NSIDC said.
Last autumn’s record low and this winter’s record ice growth show there’s a “more pronounced seasonal cycle in Arctic sea ice and the increasing dominance of first-year ice in the Arctic,” the Colorado-based centre said.