Powerful winter winds have driven a large amount of thick ice from Arctic seas into warmer waters, putting at risk the habitat of animals including polar bears and seals.
The strong winds that swirled clockwise for much of the winter pushed eight per cent of the Arctic’s “perennial ice” into the Beaufort Sea, north of mainland Canada, where two thirds of ice melts during the summer, researchers at University College London said.
Perennial ice is thicker, is more resistant to melting, has survived for at least a summer and helps keep global temperatures down by reflecting sunlight.
The new study, published in the journal Nature Communications Earth and Environment, said about half of the Arctic's perennial ice has disappeared since 1984 and was at a record low level for this time of year.
“In mid-February we saw that a strong weather system was literally spinning the Arctic sea ice around,” said UCL’s Robbie Mallett, who led the study.
“When we looked closer we saw that the Arctic’s older ice was drifting out of the ‘survival zone’ – the shrinking area where ice can still survive the summer melt season.”
The development is being blamed on a weakening of the polar vortex, a band of cold winds in the Arctic’s stratosphere. In turn, cold weather pushed south to cause the lowest UK temperatures since 1995 and freezing weather in Texas, while high temperatures and powerful clockwise winds in the Arctic drove ice south.
“Since perennial ice tends to be thicker ice that is more resistant to melting during summer, the loss ice removes the ocean’s reflective ice cover, allowing it to absorb more heat and light, which in turn melts more ice and warms the planet,” said co-author Julienne Stroeve, of UCL and University of Colorado Boulder.
Mr Mallett said that “last winter things started badly, and then they got worse”.
“We saw a record late start to the winter growth season, from which the sea ice never really recovered. We now have a record-low and precariously positioned, perennial ice cover in the Arctic’s hottest months. If this ice melts before September, then it’s gone."