This year the first-time ice-free area is extremely large— roughly the size of the state of California [410,000 sq km].
As outlined in the August 14 and August 22 reports, the atmospheric pressure pattern over the Arctic has been unusual this summer. There has been a pattern of winds bringing in warm air from the south over the coastal seas of eastern Siberian, fostering strong melt and tending to push ice from the coast into the central Arctic Ocean.
Melt has been further enhanced by the fairly clear skies under the high-pressure area, known to climatologists as an “anticyclone."
This atmospheric pattern has persisted through late August and early September. Positive temperature anomalies cover much of the Arctic Ocean, but are especially strong (up to 7 degrees Celsius) along the Siberian coast.
While consistent with the pattern of winds bringing warm air into the region, we are probably also seeing a second and quite different effect. Because oceans are so dark compared to sea ice, the immense open water areas north of Siberia absorbed a great deal of the sun’s energy through summer, hence heating the upper ocean.
Climate models have long told us that as greenhouse warming takes hold, rises in surface temperature over the Arctic Ocean will be especially large compared the rest of the Northern Hemisphere. A key part of this so-called "arctic amplification" is the growing impact through time of the very process just described. Namely, with increasingly less sea ice at the end of summer as the years pass, the heat transfer from the ocean to the atmosphere in autumn also grows.
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SOURCE: NSIDC Release on Arctic Ice Loss
Note: NSIDC Release on Arctic...
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