While high temperatures were critical to the melting seen in Greenland last year, scientists say that clear blue skies also played a key role. In a study, they found that a record number of cloud free days saw more sunlight hit the surface while snowfall was also reduced. These conditions were due to wobbles in the fast moving jet stream air current that also trapped heat over Europe. As a result, Greenland’s ice sheet lost an estimated 600 billion tonnes.
Greenland’s ice sheet is seven times the area of the UK and up to 2-3km thick in places. It stores so much frozen water that if the whole thing melted, it would raise sea levels worldwide by up to 7m. Last December, researchers reported that the Greenland ice sheet was melting seven times faster than it had been during the 1990s. In recent weeks, an analysis of last year’s melting said the 600 billion tonnes of ice added 2.2mm to global sea levels in just two months.
The exact mechanism by which climate change affects the jet stream isn’t understood. But the view is that as the Arctic warms, the temperature differences between the region and the mid-latitudes that drive the air current are reduced. This slows down the stream, making it wander further.
Source: BBC
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