Arctic still on thin ice

Although a colder-than-average winter this year has increased the amount of new sea ice, the older ice that lasts for several years has continued to decline, the researchers announced.

Perennial sea ice, that remains all year round, used to cover 50%-60% of the Arctic, but NASA said it now covers less than 30%.

Very old ice that remains in the Arctic for at least six years made up more than 20% of the Arctic area in the mid to late 1980s, but this winter resulted in just 6%.

Walt Meier, of the National Snow and Ice Data Centre at the University of Colorado, said that older ice becomes thicker, so the reduction in old ice is also making the ice cover much thinner and more vulnerable to melting in the summer.

In a telephone briefing, he told reporters: “Thickness is an indicator of long-term health of sea ice, and that’s not looking good at the moment.”

He added: “What we’re seeing with the ice cover is it’s becoming more and more empty underneath.”

Measurements taken this month by NASA and US government satellites showed the maximum area of sea ice slightly increased by 3.9% over that of the previous three years, but it is still 2.2% below the long-term average.

Researchers at NASA’s Goddard Space Flight Centre found perennial ice cover at the height of the summer melt was about 40% less than the 28-year average.

NASA said its scientists will continue to closely monitor ice levels in the region following the cold winter.

Kate Martin