2012 is the Arctic melt season to defy all previous expectation. Despite weather conditions that would enhance-refreezing, melt in important measures continues. According to NSIDC, sea ice extent is now 3.42 million square kilometers. This value is three quarters of a million square kilometers below the record low set in 2007. In total, this represents an 18% decline from the record low values set in 2007.
Other measures, including Cryosphere Today and JAXA showed sea ice melting back to near record values over the past 24 hours. It appears that JAXA may have edged out its old, unadjusted record by a small margin of about 1,900 square kilometers to reach a new record low for today. Currently Cryosphere today is showing 2.315 million square kilometers of sea ice area (within 20,000 square kilometers of the record) and JAXA is showing 3.591 million square kilometers of sea ice extent.
Anomalies for this time of year are starting to get very high. Cryosphere Today is showing that sea ice area is now less than half the average for this time of year during the already low period of 1979-2008. NSIDC’s measure for sea ice extent is now about 54% lower than it was in 1979. These values are about 66% lower than our best measurements for the 1950s. Sea ice volume is now 78% percent lower than in 1979. By any stretch, these measures represent a massive and devastating loss of sea ice.
Current departures from previous records (last record year in parenthesis) are as follows:
JAXA Extent: -659,000 square kilometers (2007)
Cryosphere Today Area: -611,000 square kilometers (2011)
PIOMAS Volume: -400 cubic kilometers (2011)
NSIDC Extent: -750,000 square kilometers (2007)
We are now in the range of 600,000 – 800,000 square kilometers below record levels that this site has been estimating for end of season melt. Given these extremely low values and the current weather situation in the Arctic, I would expect stabilization with the potential for one or two new lows with a general move toward re-freeze within the next 2-3 weeks. That said, temperatures for the Arctic are still very high for this time of year. And it also appears that there is a lot of latent heat energy being transported into the Arctic through the ocean currents. There has been recent speculation that the salt water driven currents are moving farther north, transporting more warm water to the ice sheet’s edge. This mechanism may well be behind the continued substantial erosions of sea ice so late in the season.
In general, given the anomalous and unexpectedly strong melt this year, the strength of the human caused heat forcing of the Arctic, and the amplification occurring through loss of albedo, increased local carbon releases, and alterations of atmospheric and ocean weather currents outside the range of traditional climate and weather science, all bets are off in predicting a system that has been forced well beyond its natural range of variance.