The annual maximum, which occurred on 7 March, was 14.6 million square kilometres – 1.2 million square kilometres below the 1979–2000 average. The reading tied with that of 2006 as the lowest recorded since satellite measurements began in 1979.

The seven lowest maximum sea-ice extents measured by satellites have all occurred during the past seven years, according to Walt Meier of the NSIDC. ‘I’m not surprised by the new data because we’ve seen a downward trend in winter sea ice extent for some time now,’ he said.

Meanwhile, the scientists who predicted in 2007 that the Arctic could be ice-free in 2013 have used a new computer model to produce a revised ‘best guess’ of 2016 for an ice-free Arctic. The new model has been designed to better replicate interactions among the Arctic Ocean, the atmosphere, the sea ice and rivers carrying fresh water into the sea.

‘In the past, we were just extrapolating into the future assuming that trends might persist as we’ve seen in recent times, Wieslaw Maslowski of the Naval Postgraduate School in Monterey, California, told the BBC. ‘Now we’re trying to be more systematic, and we’ve developed a regional Arctic climate model that’s very similar to the global climate models participating in Intergovernmental Panel on Climate Change assessments.’

May 11