Report confirms Arctic sea-ice melt continues

MARGARET MUNRO
Canwest News Service

There is plenty of ice at the top of the planet after last winter, but a new report indicates it may not be there for long.

The report to be published Thursday in the journal Nature includes new satellite data and concludes that excess warming between 1989 and 2008 was tied primarily to reduction in sea ice cover.

The more the ice melted, the more the upper ocean warmed and the more heat was then released back into the atmosphere, feeding the warming trend.  

“The findings reinforce suggestions that strong positive ice-temperature feedbacks have emerged in the Arctic, increasing the chances of further rapid warming and sea ice loss,” says the report.  

The rise in Arctic air temperature in the last decade has been twice the global average, with a record-breaking ice retreat in the summer of 2007.

This so-called “Arctic amplification” has been attributed to various forces, including changes in atmospheric and ocean circulation, cloud cover and water vapour.  

The report comes on the heels of a winter that saw record high temperatures — more than six degrees above normal in some parts of the Canadian Arctic — as well as substantial ice formation in the Bering Sea and Baltic Sea.

After a spring cold snap in March, Arctic sea ice reached its maximum extent of 15.25 million square kilometres, well above the record low seen in 2006, according to the U.S. National Snow and Ice Data Center that monitors the waxing and waning of the ice.

Climate change skeptics were heartened to see so much ice form this winter, but scientists say much of the ice is thin and could melt quickly when temperatures rise this summer.

And long term, they are still predicting a big thaw.

“The sea ice extent (this winter) may have been greater than in the preceding years, but the long-term trend is very much one of decreasing sea ice,” says James Screen, of the University of Melbourne in Australia, and lead author of the report.

Climate models predict the Arctic will see ice-free summers this century, which will have dramatic impacts on northern ecosystems and lifestyles.
Some scientists have suggested the summer ice could melt away within a few years; others say it will not happen for decades.

Screen declined to speculate on when it might disappear, but said by e-mail that “ the emergence of strong positive ice-temperature feedbacks make the chances of further rapid sea ice loss more likely.”

Climatologist Andrew Weaver, at the University of Victoria, says that the new report reinforces the theory that Arctic warming is being amplified in the lower atmosphere and that summer sea ice could soon be a thing of the past.

When, he says, is hard to know.

“Probably not next year, probably not the year after, but very possibly in my lifetime and yours,” says Weaver.