Antarctica melt five times faster than usual

Antarctica has lost an area of ice the size of Greater London since 2010 as warmer ocean water erodes its floating edge, a scientific study has found.

The underwater point at which floating ice shelves meet landbased ice, known as the grounding line, has retreated by five times the normal rate in some parts in the past seven years.

The findings suggest that melting glaciers on the continent could add significantly to longterm sea level rises, with severe

Melting glaciers on the continent could add significantly to long-term sea level rises, with severe implications.

implications for thousands of coastal towns and cities.

Global sea levels have been rising by about 3mm a year, mostly caused by the melting of smaller glaciers and the subseqeuent expansion of ocean water as it warms.

Previous studies have predicted that the melting of the giant glaciers in Antartica and Greenland could raise sea levels by up to 1.8 metres by 2100.

Scientists at the UK Centre for Polar Observation and Modelling at the University of Leeds estimated changes in the grounding line of Antarctic glaciers using measurements made by a radar altimeter on board the European Space Agency’s Cryosat-2 environmental research satellite.

They found significant variations, with the grounding line of some glaciers advancing but these gains were outweighed by the number retreating.

The biggest changes were seen in western Antarctica, where more than a fifth of the ice sheet has been shown to have retreated across the sea floor since 2010, significantly faster than the average long-term rate.

However, the scientists added that the melting of the Pine Island Glacier, until recently one of the fastest retreating on the continent, appears to have ‘‘paused’’.

Overall about 1,463 sq km of Antarctica’s underwater ice melted between 2010 and 2016.

Dr Hannes Konrad, the lead author, wrote in Nature Geoscience: ‘‘Our study provides clear evidence that retreat is happening across the ice sheet due to ocean melting at its base, and not just at the few spots that have been mapped before now.

‘‘This retreat has had a huge impact on inland glaciers, because releasing them from the sea bed removes friction, causing them to speed up and contribute to global sea level rise.’’