After plunging to its lowest level on record in September, Arctic sea ice extent mounted an impressive recovery this winter. But its maximum, reached March 15, still ranked 6th lowest on record. All ten of the lowest maximums on record (since 1979) have occurred in the last 10 years.
From the ice’s late summer low extent of 1.3 million square miles, it grew to 5.84 million square miles by mid-March. Or, it transformed from roughly one-third of the size of the Lower 48 to twice its size. The increase in ice from minimum to maximum was the biggest on record.
But the sea ice now covering much of the Arctic is very thin, first-year ice which is vulnerable to melting as days lengthen and temperatures warm.
Arctic sea ice volume, which provides information on the thickness of the ice as well as the extent, has been in a long-term steep decline.
Between 2003 and 2012 alone, Arctic sea ice volume dropped 9 percent in the winter according to the United Kingdom’s Natural Environment Research Council.
The summer shrinkage in volume has been even more stunning.
“Findings based on observations from a European Space Agency satellite, published online in Geophysical Research Letters, show that the Arctic has lost more than a third of summer sea-ice volume since a decade ago, when a U.S. satellite collected similar data,” reported the University of Washington in February.
Summer sea ice volume in 2012 was just one-fifth of what it was in 1980, the University of Washington said, a mind-boggling change.
For further information:
Arctic Ice Hits Annual Max and it’s 6th Lowest on Record (Climate Central)