Arctic sea ice cover could be confirmed within days as the second lowest ever recorded, the latest data suggests.
According to the US national snow and ice data centre (NSIDC) the ice which forms and disperses annually has been close to its minimum extent for the year for several days and has begun to grow again as autumn sets in.
It was measured by satellite as 4.169m sq km on 12 September, a slight increase on the 4.139m sq km on 11 September. As the Arctic winter closes in, the ice cover will climb, reaching around 15m sq km by March.
New figures present the new normal
Ice scientists said the figures were the “new normal” and confirmed the long-term downward trend towards ice-free Arctic summers.
“We are not going back to how it was. There is nothing to suggest it will stop. Eventually we will lose the summer ice. It’s not going to be next year but we are on that trajectory,” said Julienne Stroeve, a senior scientist at the NSIDC and a professor at University College London.
“Climate systems are inherently chaotic. You could have some temporary recovery of the ice but we are not going back,” she said.
“This year has shown there is no correlation between what happens in May and September. May was the lowest ever, but 2016 did not end up the lowest,” said Stroeve. “The ice has definitely been thinner this year. Thinning ice is keeping the extent lower than it would otherwise have been.”
2016 looked likely to break all records for melting when Arctic sea ice hit a record low extent over the winter. But a cloudy and cool summer is thought to have slowed the annual melt.
Major August storms stirred up broken ice
Two major storms in August probably accelerated the melt by stirring up the broken ice, said the NSIDC in its monthly bulletin.
“It appears that the August 2016 storms helped to break up the ice and spread it out. Some of this ice divergence likely led to fragmented ice being transported into warmer ocean waters, hastening the melt. Whether warmer waters from below were mixed upwards to hasten melt remains to be determined,” it said. “It may be that as the ice cover thins, its response to storms is changing.”
2016 was also marked by the absence of ice as far north as 87N, a few hundred miles from the North pole. This is extremely rare but not unprecedented, said NSIDC director, Mark Serreze.
2016 is “another year in the new normal of the Arctic”, he told Mashable.
Ice thickness reduced by 40% over 35 years
The lowest extent of sea ice ever recorded was in 2012 when it measured 3.41m square km – down from averages of around 8m sq km in the 1970s. Ice thickness has also reduced by around 40% in the last 35 years.
The melting Arctic is recognised as an indicator for climate change, with rates of warming higher than elsewhere. Many scientists expect the reduction of sea ice to allow the Arctic ocean to warm and to trigger the releases of methane, a powerful warming gas.
The result would be an Arctic “death spiral”, said Cambridge ice scientist Peter Wadhams in a book published last month.
Greenland experienced a ‘heatwave’ in early April with temperatures above 25C. Average temperatures in July were 2-4C higher than usual in many places.
By John Vidal. Source: The Guardian