Antarctica's ice sheet is melting 3 times faster than before

Antarctica's ice sheet is melting 3 times faster than before

Then the melting accelerated significantly, and since 2012 the rate has jumped to more than 241 billion tons a year - adding 0.6 mm per year to sea level rise.

The annual sea level rise that's attributed to Antarctica has tripled, from 0.2mm to 0.6mm, or from less than a tenth of an inch to almost a quarter of an inch, he says. "And the ice sheet is now losing three times as much ice", Shepherd adds.

Up to now, scientists have struggled in determining whether Antarctica has accumulated more mass through snowfall than it loses in meltwater run-off and ice flows into the ocean.

Unlike single-measurement studies, this team looks at ice loss in 24 different ways using 10 to 15 satellites, as well as ground and air measurements and computer simulations, said lead author Andrew Shepherd of the University of Leeds in England.

"The increasing mass loss that they're finding is really worrying, particularly looking at the West Antarctic, the area that's changing most rapidly and it's the area that we're most anxious about, because it's below sea level, " said Christine Dow, a glaciologist at the University of Waterloo in Canada who was not involved in the research.

Researchers found that the ice losses are largely driven by melting of the West Antarctic ice sheet, which is hit hard by warm oceans that melt ice from below.

"According to our analysis, there has been a step increase in ice losses from Antarctica during the past decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years", Shepherd said.

East Antarctica, which is home to the South Pole, has seen considerably less melting because most of its ice is above sea level. That's up from 84 billion tons ten years ago, and 54 billion tons ten years before that.

The researchers attribute the increased losses in West Antarctica and the Antarctic Peninsular to changes in regional floating-ice shelves, which can provide a buffer to continental-ice sheets. The new findings hint that the continent's ice cover may not be as resistant to warming as once thought, and present a very different picture of Antarctica's potential contributions to a rising ocean: Consider that if all of Antarctica's ice melted, the resulting water could elevate sea levels by about 190 feet (58 meters), the researchers reported. "The good news is that limited climate change can slow the rate of ice loss, and there are many proven actions that can reduce climate change and be implemented immediately".

But there is also room for caution in how this latest data is interpreted.

"It's a hard one for us to answer because the time series is still pretty short", he said.

Or alternatively, he continued, Antarctica could drive faster changes, ones that "begin to exceed what we're going to be able to cope with".

The new findings are the result of the most complete satellite survey of Antarctic ice sheet change to date, involving 84 scientists from 44 worldwide organizations (including NASA and the European Space Agency).

Another study, also published in Nature, explores how Antarctica and the Southern Ocean will change over the next 50 years, and what impact the changes will have on the rest of the globe.

Scientists have previously raised fears about a scenario in which ice loss from Antarctica takes on a rate of explosive growth.

His team analysed the Larsen A and Larsen B, and Wilkins ice-shelf disintegration events, and found that lack of sea-ice was a common factor.

"The costs for coastal resilience may have just gone up", she said. Total ice loss during the 25-year period contributed to sea level rise of about 0.3 inches (around 8 millimeters), approximately 40 percent of which - about 0.1 inches (3 mm) - happened in the past five years.

Part of West Antarctica, where most of the recent melting occurred, "is in a state of collapse", said co-author Ian Joughin of the University of Washington.

"Satellites have given us an wonderful, continent-wide picture of how Antarctica is changing", said Dr. Pippa Whitehouse, a member of the IMBIE team from Durham University, according to a University of Leeds press release.

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