Antarctic ice melting faster

Between 1992 and 2017 we have observed a threefold increase in the rate of ice loss from West Antarctica, from 53 to 159 billion tonnes a year.

"We're at a really exciting time in Antarctic glaciology, in that we have a lot of mature technologies for measuring ice-sheet changes that were not available when I started in the field in the early 2000s", Smith said.

The West Antarctic ice sheet has lost almost three trillion tonnes of ice during this span - with a large chunk of the numbers coming in the last few years, according to research.

We have found that since 1992 Antarctica has lost 2,720 billion tonnes of ice, raising global sea levels by 7.6mm. In light of the acceleration in ice loss we have observed over the past five years, we now find sea level rise from Antarctica to be tracking the IPCC's highest projection.

Most of Antarctica's ice loss measured in this study came from the West Antarctica and the Antarctic Peninsula - which scientists have known were melting.

The Atlantic noted this week that millions of people on the U.S. East Coast could be displaced from their homes by the end of the century because of melting in parts of western Antarctica ― which scientists have identified as being the source of most of the recent melting.

"According to our analysis, there has been a steep increase in ice losses from Antarctica during the last decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years", said Andrew Shepherd of the University of Leeds, UK, who led the assessment. The absence of data about the East Antarctic Ice Sheet's response to warming in the past have hindered efforts to predict its role in future sea level rise. "And the ice sheet is now losing three times as much ice", Shepherd adds.

"The next piece of the puzzle is to understand the processes driving this change", Whitehouse added.

"The data from these spacecraft show us not only that a problem exists but that it is growing in severity with each passing year", explains NASA researcher Isabella Velicogna from the University of California, Irvine.

"This is a concerning thing if you consider that ice shelves exist around 75 per cent of the periphery of Antarctica".

Between 60 and 90 percent of the world's fresh water is located in Antarctica - the size of Mexico and the United States combined - and if that were to all melt, sea levels would shoot up by nearly 61 metres, which would prove catastrophic for billions of people around the world.

"If you start removing mass from there, you can have a very large scale evacuation of ice into the ocean and significant sea level rise, " she continued. "This has to be a concern for the governments we trust to protect our coastal cities and communities".

"The power of this research is that it brings together independent methods and results from a collection of different teams throughout the world", noted Twila Moon, a scientist at the US National Snow and Ice Data Center in Colorado.

The unsettling trend is expected to continue.

As sea-ice retreats, floating Antarctic ice shelves are more exposed to destruction by wave action, according to a separate paper also published in Nature today and not affiliated with the previous study.

Antarctica is not the only contributor to sea-level rise.

Antarctica has enough ice to raise seas by 190 feet if it ever all melted, dwarfing frozen stores in places from Greenland to the Himalayas and making its future the biggest uncertainty in understanding global warming and ocean levels.

The changes will not be steady, in any case, said Knut Christianson, an Antarctic researcher at the University of Washington in Seattle, by email.

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