It’s long been known that the Arctic is losing sea ice at an increasingly rapid rate. Now NASA’s Goddard Space Center is allowing you to see just how dramatic the loss truly is.
Almost all of the top 10 records for sea ice minimums in the Arctic — the minimum occurs each September — have occurred since 2005, with 2006 being the exception.
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What the new data illustrates is that older ice is thinning, making it more vulnerable to melting, contributing to the positive feedback — when a change contributes to a change in the same direction — of a warming Arctic.
“What we’ve seen over the years is that the older ice is disappearing,” said Walt Meier, a sea ice researcher at NASA’s Goddard Space Flight Center. “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. But this older ice is becoming weaker because there’s less of it.”
This new animation illustrates the varying cycles — between winter ice growth and summer ice loss — as well as the movement and thinning.
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During each winter, the ice that manages to survive the summer melt, grows and thickens, typically about one to two metres in its first year. Ice that that has survived several melts can grow about three to four metres thick.
“Ice age is a good analogy for ice thickness because basically, as ice gets older it gets thicker,” Meier said. “This is due to the ice generally growing more in the winter than it melts in the summer.”
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The animation shows two major “bursts” of ice loss, according to NASA. The first can be seen in 1989, as a result of a shift in the Arctic Oscillation, a circulation in the atmospheric patterns. This, in turn, pushed more Arctic ice out of the region.
The second one occurred in the mid-2000s. However, this wasn’t a result of any atmospheric pattern shift. Instead, it’s a result of less older ice mixed in with younger ice, making it much easier to melt.
“We’ve lost most of the older ice: In the 1980s, multi-year ice made up 20 per cent of the sea ice cover. Now it’s only about three per cent,” 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.”
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