Record decline of polar ice sheets

Greenland’s and Antarctica’s ice sheets are declining at an unprecedented rate, researchers have found using new satellite technology.

In total, the ice sheets are losing around 500 cubic kilometres of ice per year. This ice mass corresponds to a layer that is around 600 metres thick and would stretch out over the entire metropolitan area of Hamburg, Germany’s second largest city. The research was conducted by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Germany.

The scientists evaluated and compiled data by the CryoSat-2 altimeter SIRAL. Satellite altimeters produce very accurate data and the elevation maps – which cover an area of close to 16 million square kilometres – are very accurate, to just a few metres in height.

The results reveal that Greenland alone is reducing in volume by about 375 cubic kilometres per year, and has doubled since 2009. The loss of the West Antarctic Ice Sheet has increased by a factor of 3 in the same time period.

“Combined the two ice sheets are thinning at a rate of 500 cubic kilometres per year. That is the highest speed observed since altimetry satellite records began about 20 years ago,” says glaciologist Prof. Dr. Angelika Humbert, one of the study’s authors.

But whereas both the West Antarctic Ice Sheet and the Antarctic Peninsula, on the far west of the continent, are rapidly losing volume, East Antarctica is gaining volume – though at a moderate rate that doesn’t compensate the losses on the other side of the continent.

“We need to understand where and to which extent the ice thickness across the glaciers has changed. Only then can we can analyse the drivers of these changes and find out how much ice sheets contribute to global sea level rise”, says lead author Dr. Veit Helm.

 

Photo credit: Glacier border in the Antarctic. Alfred-Wegener-Institut

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