Published: Fri, June 15, 2018
Sci-tech | By Patricia Wade

Antarctica Has Lost 3 Trillion Tonnes of Ice Since '92

Antarctica Has Lost 3 Trillion Tonnes of Ice Since '92

And the ice losses quickened to 219 billion tons a year since 2012, from 76 billion previously.

"The kinds of changes that we see today, if they were not to increase much more. then maybe we're talking about something that is manageable for coastal stakeholders, " said DeConto.

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.

In April, a team of United Kingdom researchers released a report saying that underwater glaciers in Antarctica are melting at an "alarming rate".

While the sediment was the product of erosion from the continent, the low levels of tell-tale chemical signatures reveal that the sediment experienced only minimal exposure to cosmic radiation, leading the team to conclude East Antarctica must have remained covered in ice.

Altogether, across the continent, 34,000 square kilometers (13,000 square miles) of the ice shelf has been lost since the 1950s.

The Antarctic ice sheet has lost more than 2,500 billion tonnes of ice in the past 25 years and almost half of that has happened since 2012.

While the current ice loss measured is literally a drop in the ocean compared to Antartica's catastrophic potential to raise global sea level by as much as 58 metres (190 ft) if the ice sheets were to completely melt, the apparent acceleration in the latest satellite observations is enough to have scientists duly anxious. Over the coming decades, rising sea levels from melting ice and the expansion of warming oceans will strain societies and economies worldwide.

In a new study, the most comprehensive to date of the continent's icy status, an global group of 84 researchers analyzed data from multiple satellite surveys, from 1992 to 2017. The increases are on the order of a few millimetres per year, but scientists need to account for them to ensure their other measures of ice loss are accurate.

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"I don't know if it's going to keep exactly tripling, but I think it has a lot of potential to keep significantly increasing, " said Velicogna. But clues from the geologic record suggest that the climate change driving ice loss in Antarctica is doing so much faster than during its periods of ice loss in the distant past, Shepherd told Live Science.

Another component of the East Antarctic Ice Sheet, marine-based ice, sits below sea level and is thus directly affected by the ocean.

It's possible, however, that Antarctica alone can add about half a foot to sea level rise by the end of the century, said Andrew Shepherd, the lead author of the study and a professor of earth observation at the University of Leeds in England.

"According to our analysis, there has been a steep 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.

The government wants an action plan in place to tackle climate change after a new report details its impact on health.

Looking closer, the rapid, recent changes are nearly entirely driven by the West Antarctic ice sheet, which scientists have long viewed as an Achilles' heel. This uncertainty persists because global sea level estimates for the Pliocene have large uncertainties and can not be used to rule out substantial terrestrial ice loss, and also because direct geological evidence bearing on past ice retreat on land is lacking.

Sea level contribution due to the Antarctic ice sheet between 1992 and 2017.

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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