Arctic explorers may have explained why sea ice melting so fast

Bob Weber - The Canadian Press

A 500-kilometre walk over treacherous Arctic terrain has resulted in a possible explanation for why sea ice in northern waters is melting so much more rapidly than anyone thought it would.

"We're trying to understand why the ice is melting so fast," said Simon Boxall of the Catlin Arctic Survey. "It's not just down to simple warming. There are more complicated processes."

The speed at which sea ice is disappearing in the Arctic has far exceeded almost all predictions and alarmed climate scientists.

A 2007 paper from the National Snow and Ice Data Center in Boulder, Colo., found that the projections of the UN-sponsored Intergovernmental Panel on Climate Change were already obsolete three years after they were published.

When projections from the panel were compared with actual observations, the authors found that between 1953 and 2006 the sea ice was retreating three times faster than it should have. Between 1979 and 2006, when satellite data was available, the actual retreat was twice as fast as climate models predicted.

The report concluded that sea ice retreat is 30 years ahead of where scientists thought it would be.

"Decay of the ice cover is proceeding more rapidly than expected based on the model simulations," said the report published in Geophysical Research Letters.

The team at the Catlin Arctic Survey, sponsored by the Catlin Group insurance company, thought the answer might lie in different temperatures at different levels of Arctic seas.

Such data is usually obtained from ships. But during the spring, when melting is greatest, there's still too much sea ice for ships to make it through.

So the scientists walked from Borden Island to Ellef Ringnes Island and also from near the North Pole all the way down to the northern tip of Ellesmere Island, slogging about 10 kilometres a day in below-deep-freeze temperatures over rugged, uneven ice.

What they found was a surprise — a layer of seawater about 200 metres below the surface that was actually colder than when it had been measured by previous expeditions.

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