Geophys. Res. Lett. 35, L01703 (2008)

Credit: US NATIONAL SNOW AND ICE DATA CENTER

Arctic sea ice is retreating at an accelerating pace, with scientists describing the decline from July to September 2007 as “precipitous”. At the end of the 2007 summer melt, the area of ice cover was 38 percent less than the average since 1978. The decline had averaged 3 percent per decade from 1978 to 1996, but more than tripled to 11 percent from 1996 to 2007.

NASA scientists Josefino Comiso and Claire Parkinson analysed the latest data and found that 14 September 2007 marked the record minimum of Arctic ice since satellite observations began. The decline from 2005 to 2007 represented a summertime ice loss roughly the size of Egypt. The researchers attribute the exceptional loss in 2007 in part to higher sea surface temperatures and warm southerly winds reaching the Beaufort and Chukchi Seas, but they say that other factors play a role. In particular, open water absorbs more sunlight than ice, further warming the Arctic Ocean; this has created a feedback mechanism over the past decade, leading to further ice loss.

The Arctic could be ice-free in summer within a few decades, the researchers say, with major consequences for ecosystems. Given further predicted warming, they do not anticipate a reversal of the trend anytime soon.