Tuesday, March 23, 2010

Will the Arctic be free of summer ice in 30 years?

Translation from the article of Denis Delbecq

In a work published in Geophysical Research Letters, a Japan-US team proposes another way, (additionally to the planet's warming) for explaining the rapid disappearance of sea ice in the Arctic.
The three researchers have studied the wind regime in the Arctic Ocean for 31 years. And they have noted that it has changed. Moreover, they reveal a direct link between weather anomalies (located north of Greenland and in the Beaufort Sea) and the minimum extent of polar sea ice, raised each year in September. Basically, the winds tend to push the ice towards the south, and get them across the Fram Strait, the gateway to warmer waters leading to their rapid disappearance.

According to this work, the wind patterns explain half the variation of ice extent recorded from one year to another. On a scale climate (the 31 years of the study), winds explain about one third of the trend towards reduction of Arctic sea ice at the end of the summer. That is a second figure more representative of what is a climate, whose evolution is measured in decades rather than one year to another. The researchers also stressed that their results on wind regimes contradict others. Further work will be needed to decide.

Meanwhile, a question mark remains, which no one can answer today: what is the origin of weather regime changes during summer in the Arctic?
Global warming is not just hot air or hot water, which melts the ice. In short, these mass movements southward may be linked, or not be linked to global warming. That is the question.

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