Accelerating Polar Ice Melt Approaches Tipping Point |
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Perennial ice cover (or ice at the end of the summer) is currently declining at the rate of 11.4% per decade as observed from 1978 to 2007. Acceleration in the decline makes it difficult for ice to recover because of ice-albedo feedback effects which has caused increases in solar heating of the mixed layer on account of the observed increase in open water area of 23% per decade in the Arctic basin since 1978. Such feedback effect is reflected in the unexpectedly large decline (39% lower than average in the perennial ice cover in 2007. Concurrently, the sea surface temperature was anomalously warm (4oC higher than average) and has been increasing at the rate of 0.7 0C/decade in the Beaufort/Chukchi Seas region since 1981. We postulate that the perennial ice has reached its tipping point and will continue to decline. http://neptune.gsfc.nasa.gov |