Rate of Antarctica's ice melting has tripled since 2012, study finds

Christopher Davidson
June 14, 2018

But that has changed.

Between 2012 and 2017 the continent lost 219 billion tonnes of ice per year - a 0.6mm per year sea level contribution. "And the ice sheet is now losing three times as much ice", Shepherd adds.

A collective effort by over 80 scientists across the world used satellite data to determine estimates of ice-sheet mass balance between 1992 and 2017, ultimately calculating that global sea level increased by 7.6 mm in the period.

"That's a big jump, and it did catch us all by surprise", Shepherd says. "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", Andrew Shephard, lead author of the study and a professor at the University of Leeds, said in a statement.

"There are no other plausible signals to be driving this other than climate change". Just one East Antarctic glacier, an enormous mass dubbed Totten, could cause a sea-level rise equal to what could be triggered by the entirety of the West Antarctic sheet, the Washington Post notes.

Shepherd said the ice on West Antarctica can be melted by very small changes in ocean temperature.

West Antarctica is now bearing the brunt of this loss, as its glacial ice shelves have been melted from below by warming deep ocean water.

Between 60 per cent and 90 per cent of the world's fresh water is frozen in the ice sheets of Antarctica, a continent roughly the size of the United States and Mexico combined.

The latest data is a continuation of previous assessments known as the Ice sheet Mass Balance Inter-comparison Exercise (IMBIE), which began in 2011 and tracks ice-sheet loss from 1992 onwards.

Researchers say floating ice-shelf loss has triggered the faster loss of West Antarctic ice.

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Whether Antarctic mass loss keeps worsening depends on choices made today, argues DeConto, who co-authored a separate paper in this week's Nature outlining two different visions for Antarctica's future in the year 2070.

"Some of the estimates covered different proportions of the ice sheets, some of them covered different time periods, and all of them used different methods and so it became hard for people who are not specialists to try to pick them apart", says Shepherd. "The length of the satellite record now makes it possible for us to identify regions that have been undergoing sustained ice loss for over a decade".

To analyze the ice, the researchers use three different kinds of measurements.

Covering twice the area of the continental United States, Antarctica is blanketed by enough ice pack to lift global oceans by almost 60 metres (210 feet).

Finally, the scientists are recording gravity measurements for Antarctica.

The melting of Antarctica is accelerating at an alarming rate, with about 3 trillion tons of ice disappearing since 1992, an worldwide team of ice experts said in a new study.

Shepherd says that actually, their data shows a "a progressive increase in ice loss throughout the whole 25 year time period".

Continuing high emissions could deliver massive sea level rise - but strong compliance with the Paris climate agreement, while unable to stop changes happening now, could help to control how much they worsen. Now, the continent looks to be tracking towards the upper range, which would mean a rise of 15 centimeters by the end of the century.

Crevasses form on Pine Island Glacier in Antarctica, near the part of the glacier where it leaves land and extends over the ocean.

Per the team's calculations, a high emissions scenario - in which carbon emissions rise unabated and environmental protections in Antarctica are not implemented - global air temperature would rise almost 3.5°C above 1850 levels by 2070, with sea level rise averaging somewhere between 10-15 mm every year.

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