Wed, Sep 19, 2012 - Page 9 News List

Staggering decline of sea ice threatens life

Scientists on a research ship exploring the extent of the north pole ice cap melt have been shocked at the speed with which it is receding

By John Vidal  /  The Guardian

Illustration: Mountain People

We are a few hundred miles from the north pole. The air temperature is minus-3?C, the sea is freezing. All around us in these foggy Arctic waters at the top of the world are floes — large and small chunks of sea ice that melt and freeze again with the seasons.

Arne Sorensen, our Danish ice pilot, is 18m up in the crow’s nest of the Arctic Sunrise vessel. Visibility is just 200m and he inches the 1,000 tonne Greenpeace ice-breaker forward at two knots through narrow passages of clear water. The floes are piled up and compressed in fantastic shapes. Two polar bears on our port side lift their heads, but resume hunting. Sorensen has sailed deep into ice at both poles for 30 years, but this voyage is different, he says. The edge of the Arctic ice cap is usually much further south of where we are now at the very end of the melt season. More than 600,000km2 more ice has melted this year than ever recorded by satellites. Now the minimum extent has nearly been reached and the sea is starting to refreeze.

“This is the new minimum extent of the ice cap,” he says — the frontline of climate change. “It is sad. I am not doubting this is related to emitting fossil fuels to a large extent. It’s sad to observe that we are capable of changing the planet to such a degree.”

The vast polar ice cap, which regulates the Earth’s temperature, has this year retreated further and faster than anyone expected. The previous record, set in 2007, was officially broken on Aug. 27 when satellite images averaged more than five days showing the ice then extended 4.11 million square kilometers, a reduction of nearly 50 percent compared with just 40 years ago.

Since Aug. 27, the ice has just kept melting — at nearly 40,000km2 a day until a few days ago. Satellite pictures this weekend showed the cap covering only 3.49 million square kilometers. This year, 11.7 million square kilometers of ice melted, 22 percent more than the long-term average of 9.18 million square kilometers.

The record minimum extent is soon expected to be formalized by the US National Snow and Ice Data Centre (NSIDC) in Colorado.

The record has not just been broken, it has been smashed to smithereens, adding weight to predictions that the Arctic may be ice-free in summer within 20 years, British, Italian and US-based scientists on the Arctic Sunrise say. They are shocked at the speed and extent of the ice loss.

The Cambridge University sea-ice researcher Nick Toberg, who has analyzed underwater ice thickness data collected by British nuclear submarine HMS Tireless in 2004 and 2007, said: “This is staggering. It’s disturbing, scary that we have physically changed the face of the planet. We have about 4 million square kilometers of sea ice. If that goes in the summer months that’s about the same as adding 20 years of CO2 at current [human-caused] rates into the atmosphere. That’s how vital the arctic sea ice is.”

The NSIDC scientist Julienne Stroeve adds: “In the 1970s we had 8 million square kilometers of sea ice. That has been halved. We need it in the summer. It has never decreased like this before. We knew the ice was getting thinner, but I did not expect we’d lose this much this year. We broke the record by a lot.”

“The acceleration of the loss of the extent of the ice is mostly because the ice has been so thin. This would explain why it has melted so much this year. By June, the ice edge had pulled back to where it normally is in September,” he added.

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