NASA images reveal how Arctic sea ice has disappeared over three decades
NASA has released a time-lapse animation showing how the Arctic sea ice has changed since the 1980s, claiming it is losing its 'bulwark' or defensive wall against warming summers.
The new visualisation was shared by NASA on October 29 and is looking at the ice age of the "vast sheath of frozen seawater floating on the Arctic Ocean" over the past three decades.
NASA said: "Direct measurements of sea ice thickness are sporadic and incomplete across the Arctic, so scientists have developed estimates of sea ice age and tracked their evolution from 1984 to the present."
A sea ice researcher at NASA’s Goddard Space Flight Center, Walt Meier, said over the years the older ice has been disappearing.
"This older, thicker ice is like the bulwark of sea ice: a warm summer will melt all the young, thin ice away but it can’t completely get rid of the older ice," said Mr Meier.
"But this older ice is becoming weaker because there’s less of it and the remaining old ice is more broken up and thinner, so that bulwark is not as good as it used to be."
NASA claimed the animation displayed two main bursts of thick ice loss over this time period, one which spanned a few years and started in 1989.
"(It) was due to a switch in the Arctic Oscillation, an atmospheric circulation pattern, which shrunk the Beaufort Gyre and enhanced the Transpolar Drift Stream, flushing more sea ice than usual out of the Arctic," NASA stated.
It said the second burst began in the mid-2000s.
"We’ve lost most of the older ice: In the 1980s, multiyear ice made up 20 percent of the sea ice cover. Now it’s only about 3 percent," Mr Meier said.
"The older ice was like the insurance policy of the Arctic sea ice pack: as we lose it, the likelihood for a largely ice-free summer in the Arctic increases."
NASA reports there were 1.86 million square kilometers of old ice which were five-years-old or more in September 1984 throughout the Arctic sea ice cap, reportedly at the lowest annual amount.
Thirty-two years later and the agency has said there are just 110,000 square kilometers of older sea ice left.
"Unlike in the 1980s, it’s not so much as ice being flushed out –though that’s still going on too," Mr Meier said.
"What’s happening now more is that the old ice is melting within the Arctic Ocean during the summertime.
"One of the reasons is that the multiyear ice used to be a pretty consolidated ice pack and now we’re seeing relatively smaller chunks of old ice interspersed with younger ice.
"These isolated floes of thicker ice are much easier to melt."
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