With a few weeks in the melt season yet to go, Arctic sea ice has broken the record for minimum summer extent. Satellites registered 4.1 million square kilometres of sea ice on 26 August, edging out the record of 4.17 million square kilometres set on 18 September 2007, according to scientists at NASA and the National Snow and Ice Date Center (NSIDC) in Boulder, Colorado.
It’s not clear what the new record will look like when the final numbers come in, but as this graph suggests, the trend is fairly clear. And then there’s this statistic: counting 2012, the six lowest sea ice minimums on record have all occurred in the past six years. In the image above, the orange line shows the average minimum extent from 1979–2010.
The details matter. One key question is the extent of ice that is thick enough to survive the summers and stick around for several years at a time; scientists have documented a shift towards thinner and more seasonal ice. NSIDC scientists won’t be releasing their final assessment until early October, but director Mark Serreze offered this quick analysis: “The previous record, set in 2007, occurred because of near perfect summer weather for melting ice. Apart from one big storm in early August, weather patterns this year were unremarkable. The ice is so thin and weak now, it doesn’t matter how the winds blow.”