Arctic sea ice hits record low in April, ice tracking centre says

This graph shows the big drop in the April sea ice extent between 1979 and 2018, with an average decline of 2.6 per cent per decade. (IMAGE COURTESY OF THE NATIONAL SNOW AND ICE DATA CENTER)

Sea ice extent retreated across most of the Arctic last month, except in Hudson Bay and in the Davis Strait.

That decrease means 2018 is roughly tied with 2016 for the lowest April sea ice extent on record, the National Snow and Ice Data Center said on Thursday, May 3.

The Colorado-based data centre, which has tracked sea ice with satellites since 1979, said that last month’s Arctic sea ice extent averaged 13.71 million square kilometres.

That’s 980,000 square kilometres below the 1981 to 2010 average and only 20,000 square kilometres above the record low April extent set in 2016.

Sea ice extent in the Bering Sea remains the lowest recorded since at least 1979, creating many coastal hazards this past winter, the NSIDC said.

Air temperatures in April, at about 760 metres above sea level, reached up to 10 C higher than average, in areas stretching towards the pole.

Air temperatures were also up to 5 C above average within the East Greenland Sea and 3 C above average over Baffin Bay.

Near the pole, there are large patches of first-year ice among the multi-year ice, and only one per cent of the ice cover is five years old or older—also the least amount ever recorded, the NSIDC said.

Also, in February, a large polynya opened north of Greenland, lasting through the first week of March, the NSIDC said.

The polynya was driven in part by strong winds from the south and “unusually high air temperatures,” the centre said.

On Feb. 24, at Cape Morris Jesup, Greenland’s northernmost station, the temperature surged well above freezing, reaching 6.1 C.