Arctic melt 'like doubling CO2'

5 September 2012 Last updated at 14:20 ET By Susan Watts Newsnight Science editor, BBC News

Loss of Arctic ice is effectively doubling mankind's contribution to global warming, ice scientist Professor Peter Wadhams has told BBC Newsnight.

White ice reflects more sunlight than open water, acting like a parasol.

Melting of white Arctic ice, currently at its lowest level in recent history, is causing more absorption.

Prof Wadhams calculates that this increased absorption of the sun's rays is "the equivalent of about 20 years of additional CO2 being added by man".

The Cambridge University expert says that the Arctic ice cap is "heading for oblivion".

In 1980, the Arctic ice in summer made up some 2% of the Earth's surface. But since then the ice has roughly halved in area, and the volume of ice has dropped to just a quarter of what it was.

"The volume of ice in the summer is only a quarter of what it was 30 years ago and that's really the prelude to this final collapse," Prof Wadhams said.

The polar ice cap acts as a giant parasol, reflecting sunlight back into the atmosphere in what is known as the albedo effect.

But white ice and snow reflect far more of the sun's energy than the open water that is replacing it as the ice melts.

Instead of being reflected away from the Earth, this energy is absorbed, and contributes to warming.

Parts of the Arctic Ocean are now as warm in summer as the North Sea is in winter, Prof Wadhams said.

UK weather effect

The melting ice could have knock-on effects in the UK. Adam Scaife, from the Met Office Hadley Centre told Newsnight it could help explain this year's miserable wet summer, by altering the course of the jet stream.

"Some studies suggest that there is increased risk of wet, low pressure summers over the UK as the ice melts."

There may be effect for our winters too: "Winter weather could become more easterly cold and snowy as the ice declines," Mr Scaife said.

Opinions vary on the date of the demise of summer sea ice. The Met Office says it is not expecting the Arctic to be completely ice-free in summer until after 2030.

Watch Susan Watts' report on changes in the Arctic and what it means for us on Newsnight on Wednesday 5 September 2012 at 10.30pm on BBC Two.

Source: http://www.bbc.co.uk/news/science-environment-19496674#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa

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