It is a mild, sunny day in June. Off the coast of far northern Canada, the icebreaker Amundsen is having little trouble ploughing through the land-fast ice. The sky is azure — the ice beneath it is rapidly melting and breaking up. “I've been doing research in the Arctic for 25 years now, but I've never seen such a long period of clear skies and mild weather,” says Dave Barber, lead scientist for the sea-ice study under way, looking out from the Amundsen's bridge.
Only a few days earlier, on this same spot in Darnley Bay, scientists had deployed monitoring equipment on what seemed like stable ice. When they returned, the ice had broken up into a jigsaw puzzle of myriad floes. On one, a meteorological tower was drifting precariously close to the edge. Barber sent out a flat-bottomed 'skippy' ice boat (pictured above) to retrieve the precious station, then dispatched a helicopter to search for other instruments that had been scattered adrift on other floes. Remarkably, all were retrieved within an hour.
The Amundsen sits in just one tiny area of the vast patchwork of floating ice that covers much of the Arctic Ocean. But it happens to provide a first-hand look at a scientific question with a peculiarly iconic importance: will this summer break last year's record low in the extent of Arctic ice cover? Last September, at the end of the melt season, the sea-ice area measured just 4.3 million square kilometres, 39% less than the long-term average for 1979–2000. Coming on top of a long-term trend towards shrinking sea ice1, this observation prompted ever-more-gloomy predictions that the Arctic summers will become entirely ice-free — perhaps as early as five years from now.
So far, the 2008 sea-ice cover is not dramatically below average (see map). In fact, at the end of June, ice covered 7.8 million square kilometres of the Arctic Ocean, compared with 7.5 million square kilometres at the same time last year. The difference is that much of the ice this year is first-year ice — frozen only last winter — and thus much thinner and more prone to melting than ice built up year on year. The factors contributing to the record-low ice cover in 2007 included a high-pressure weather system that settled in over the Beaufort Sea and a low-pressure system over Siberia; strong winds persisted between the two, which helped to shift around and melt the ice throughout the summer2. Whether similar weather patterns will come into play during July and August this year remains to be seen, says Mark Serreze, a sea-ice expert at the University of Colorado at Boulder.
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http://www.nature.com/news/2008/080716/full/454266a.html
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