Image of Arctic sea ice at its 2012 minimum courtesy of NASA
Record Meltdown of Arctic Sea Ice
On September 16, 2012, the extent of ice covering the Arctic Ocean reached an all-time low of 3.4 million square kilometers (since satellite records began in 1979). The minimum ice cover each summer had begun to shrink annually in 2000 and declined much more rapidly each year beginning in 2007.
Whereas happy shipping moguls marveled at how less ice might allow them to send freighters across the Arctic, scientists began to demonstrate and speak out about several serious effects. First, the dramatic disappearance of summer sea ice, which was not predicted by many climate models, exposes darker ocean water that absorbs more heat, thereby melting even more ice—setting up a feedback loop that may be increasing the rate of global warming.
Second, scientists maintained that the lack of ice caused the weird weather experienced in the U.S. Northeast and Europe during the past three winters. In essence, the lack of ice allows the jet stream to either dip farther south or remain farther north than usual during winter, and to get stuck in those positions for long periods, causing many consecutive days of extreme cold or exceptional warmth on either side of the Atlantic Ocean.
Some scientists ventured to say that the loss of sea ice helped Hurricane Sandy “turn left” from the Atlantic Ocean into New Jersey and New York City. Such a shift in direction had never been recorded before. A “blocking high pressure system” in the North Atlantic—a likely result of the lack of ice—prevented Sandy from heading northeast out to sea, as hurricanes would typically do. —Mark Fischetti
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