Floating ice shelves fringing Antarctica have thinned by almost a fifth in some areas over nearly two decades, research shows.

Satellite observations have revealed that the ice loss is accelerating. Total ice shelf volume around the continent changed very little from 1994 to 2003, then went into rapid decline.

Earlier gains in East Antarctic ice shelf volume observed earlier ceased after about 2003, according to the data.

US researcher Fernando Paolo, from the Scripps Institution of Oceanography at the University of California, San Diego, said: “Eighteen per cent over the course of 18 years is really a substantial change. Overall, we show not only the total ice shelf volume is decreasing, but we’ve seen an acceleration in the last decade.”

While melting ice shelves do not themselves cause sea levels to rise, they have an indirect effect, the scientists pointed out. Their loss allows more water from ice melting on land to flow into the oceans.

Future studies will focus on the causes behind the changes, including the impact of the atmosphere and ocean.

In many places there has been sustained ice shelf thinning

“We’re looking into connections between El Niño events in the tropical Pacific and changes in the Antarctic ice sheet,” said Paolo. “It’s very far apart but we know that these teleconnections exist. That may ultimately allow us to improve our models for predicting future ice loss.”

El Niño is a cyclical Pacific climate system marked by an influx of warm water off the western coast of South America that can affect weather around the world.

The findings are reported in the latest edition of the journal Science.

British expert Andrew Shepherd, director of the Centre for Polar Observation and Modelling at the University of Leeds, said: “The floating ice shelves that fringe Antarctica are an incredibly important part of earth’s climate system because they help to stabilise the ice that is locked behind them.

“This new study shows that in many places there has been sustained ice shelf thinning as a result of increased ocean melting, with some Antarctic shelves losing a fifth of their ice in less than two decades.

“This is a real concern, because such high rates of thinning cannot be sustained for much longer, and because in the places where Antarctic ice shelves have already collapsed this has triggered rapid increases in the rate of ice loss from glaciers above ground, causing global sea levels to rise.”

David Vaughan, director of science at the British Antarctic Survey (BAS), described the research as an “excellent piece of work”.

He added: “Previous work led by BAS in 2010 showed the rates at which the various floating ice shelves around Antarctic were thinning, but this paper takes that work forward by showing how that thinning has changed over time. This new insight will allow us to improve our understanding of how the oceans around Antarctica are driving change in the ice sheet.”

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