You know when climate change is biting hard when instead of a vast expanse of snow the North Pole is a vast expanse of water. This year, for the first time, Arctic scientists are preparing for that possibility.
"The set-up for this summer is disturbing," says Mark Serreze, of the US National Snow and Ice Data Center (NSIDC). A number of factors have this year led to most of the Arctic ice being thin and vulnerable as it enters its summer melting season.
In September 2007, Arctic sea ice reached a record low, opening up the fabled North-West passage that runs from Greenland to Alaska.
"There is this thin first-year ice even at the North Pole at the moment," says Serreze. "This raises the spectre – the possibility that you could become ice free at the North Pole this year."
