By Janet Raloff
The northern polar region’s climate has materially changed over the past five years, a team of 121 scientists from 14 nations concludes in a December 1 Arctic report card. Compared with 2006 and earlier, they note, the Arctic is warmer and less icy.
Sufficient observational data now exist “to indicate a shift in the Arctic Ocean system since 2006,” says Jacqueline Richter-Menge of the U.S. Army’s Cold Regions Research and Engineering Laboratory in Hanover, N.H., a coeditor of the new analysis. “This shift is characterized by the persistent decline in the thickness and summer extent of sea-ice cover and by a warmer, less salty upper ocean.”
Triggering that turning point, Richter-Menge says, were unusually warm Arctic temperatures in 2006 together with a persistent weather pattern that pushed ice across the Arctic and into the North Atlantic through the Fram Strait east of Greenland: “We like to call it the perfect storm of the Arctic.”