Superstorm Sandy and Arctic Sea-Ice Loss: Is There a Connection?

During the summer of 2012, the amount of sea ice on the Arctic Ocean was diminished to about half of its normal extent and 25% of its normal volume relative to the nearly steady conditions that existed before the 1980s. This record loss continues an inexorable decline observed during recent decades. The dramatic increase in open water allows more solar energy to enter the Arctic Ocean rather than being reflected to space by the previously extensive ice cover. Most of this extra heat returns to the atmosphere in autumn, contributing to the Arctic's rate of warming exceeding that of mid-latitudes by a factor of two to three, a phenomenon called Arctic Amplification (AA). During October 2012, prior to the arrival of Superstorm Sandy along the eastern seaboard, AA was particularly strong, resulting in a substantial weakening of the poleward temperature gradient in the northern hemisphere. Evidence will be presented suggesting that the anomalous Arctic warming following the record sea-ice losses in summer 2012 contributed to the formation of the strong and persistent high-pressure blocking pattern that was a key factor in Sandy's unusual evolution: it created a steep pressure gradient extending from the mid-Atlantic to Nova Scotia that generated a huge expanse of tropical-storm-force onshore winds, those winds drove a destructive storm surge and wind waves, and the flow helped steer Sandy on its unprecedented path into the coast of New Jersey.