Azara Blog: Old Arctic ice allegedly being lost faster

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Date published: 2008/03/18

The BBC says:

The Arctic is losing its old, thick ice faster than in previous years, according to satellite data.

The loss has continued since the end of the Arctic summer, despite cold weather across the northern hemisphere.

The warm 2007 summer saw the smallest area of ice ever recorded in the region, and scientists say 2008 could follow a similar pattern.

Older floes are thicker and less saline than newly-formed ice, meaning they can survive warm spells better

Ice more than two years old now makes up about 30% of all the ice in the Arctic, down from 60% two decades ago.
The loss of old, thick ice has continued through the winter months, despite the unusually cold weather deriving from La Nina conditions (the other extreme of the El Nino Southern Oscillation) in the Pacific.

The winter ice loss is thought to be driven mainly by the transport of old floes from Arctic waters out into the Atlantic Ocean. The currents driving this are stronger than usual as a consequence of another natural cycle, the Arctic Oscillation.

The net result is that most of the cover consists of ice that has formed since last summer.

The scientists behind these findings believe this year's cooling should not obscure the long term warming trend, with temperatures across the Arctic rising about twice as fast as the global average.

An interesting set of data, but nothing that changes the overall view of the situation.

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