Largely unnoticed, a silent drama has been unfolding over the past weeks in the Arctic. The long-term consequences will far outstrip those of the international debt crisis or the demise of the Libyan dictatorship, the news stories now commanding media attention. The drama – more accurately, a tragedy – playing out in the north is the rapid disappearance of the polar ice cap, the Arctic Ocean's defining feature.
In September, the sea-ice cover on the Arctic Ocean melted all the way back to the record-low level recorded in September 2007. At 4.4 million square kilometres, it was the smallest ice cover since satellite observations began 40 years ago, with 40% less ice than in the 1970s and 1980s.
Back in 2007, the record low stunned climate scientists, who considered it an outlier in an otherwise much slower decline in sea-ice cover. We blamed unusual wind conditions in the Arctic that year. But satellite data since then have proven us wrong. This year, we reached the same low level without exceptional wind conditions. It is now clear that we are not just seeing a steady decline of sea-ice cover, but a rapidly accelerating decline.