Antarctic ice is melting super fast

Sea levels worldwide will rise higher than anticipated, thanks to a new once-stable region of Antarctica that is suddenly melting, and at a fast rate. Analysis of satellite data shows that although the massive ice sheet on the Southern Antarctic Peninsula, made up of multiple glaciers, was rock solid from 2000 to 2009, since then it has begun to melt rapidly. The glaciers, stretching along 750 kilometers of coastline, are shedding 60 cubic kilometers of ice into the ocean each year—about 70,000 Empire State Buildings of ice annually.

The onset of such rapid loss “came as a surprise to us,” says Bert Wouters, a fellow at the University of Bristol, who led the analysis, published in the May 22 issue of Science. In just a few years, he says, the dynamics of the region “completely shifted”. The surface of some of the glaciers is dropping by as much as 4 meters each year, as measured by remote-sensing instruments on the CryoSat-2 satellite. The ice loss is so great it is also causing changes in Earth’s gravitational field, which have been detected by GRACE (gravity and climate experiment) satellites.

Wouters says the glaciers’ quick disappearance is not caused by a reduction in annual snowfall or by warmer air temperatures. It is caused by thinning ice shelves; bulky glacial sheets on land transition into large, flat ice shelves that float on the ocean. When the shelves are thick, they slow or even stop the glaciers they are connected to from gently sliding into the sea, at the mercy of gravity. But if the shelves thin too much they can no longer hold back the enormous ice mass on land, and the glaciers accelerate their march into the ocean.

Overall, the ice shelves along the Southern Antarctic Peninsula have lost almost one-fifth of their thickness since the early 1990s. Scientists say the likely cause is a change in winds across the Southern Ocean, a result of climate change. The shifting winds are pushing warmer water to ward the ice shelves, melting them from below, and against the glacial ice along the coast, melting it as well.