Antarctica has lost nearly 3 trillion tonnes of ice since 1992

June 14, 2018 by Thomas Slater And Andrew Shepherd, The Conversation
Credit: Christian Wilkinson / shutterstock

It can be easy to overlook the monstrous scale of the Antarctic ice sheet. Ice, thick enough in many places to bury mountains, covers a continent roughly the size of the US and Mexico combined. If it were all to melt, as it has in the past, global sea levels would rise by 58 metres. While this scenario is unlikely, Antarctica is so massive that just a small fraction of this ice melting would be enough to displace hundreds of millions of people who live by the coast.

Low-lying cities face the threat of flooding when extreme weather coincides with high tides. Although typically rare, these events are already increasing in frequency, and will become commonplace as global sea levels increase. Over the coming decades, rising sea levels from melting ice and the expansion of warming oceans will strain societies and economies worldwide. Improving our understanding of how much Antarctica has contributed to in the past, and how much it will contribute in the future, is vital to informing our response to climate change.

Achieving this is impossible without satellites. Antarctica is too vast, too remote – satellites are our only means of monitoring its behaviour on a continental scale. Satellites launched by the European Space Agency and NASA allow scientists to monitor changes in ice height, ice velocity and ice mass through changes in Earth's gravity field. Each of these satellites provide an independent way to measure Antarctica's past contribution to sea level rise.

Sea level contribution due to the Antarctic ice sheet between 1992 and 2017. Credit: imbie/Planetary Visions, Author provided

The ice sheet mass balance inter-comparison exercise (IMBIE) is an international effort: a team of 84 polar scientists from 44 organisations, including both of us, working together to provide a single, global record of from Earth's polar ice sheets. In our latest assessment, published in Nature, we used 11 different satellite missions to track Antarctica's sea level contribution since the early 1990s.

We have found that since 1992 Antarctica has lost 2,720 billion tonnes of ice, raising global sea levels by 7.6mm. What is most concerning, is that almost half of this ice loss has occurred in the past five years. Antarctica is now causing sea levels to rise at a rate of 0.6mm a year – faster now than at any time in the past 25 years.

Most of this ice loss has come from West Antarctica. In the Amundsen Sea Embayment (named after Roald Amundsen, one of the first explorers to reach the South Pole) warming ocean temperatures have reduced the floating ice shelves which slow the flow of the mighty Pine Island and Thwaites Glaciers, resulting in a rapid acceleration of ice losses. 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. In the Antarctic Peninsula, the collapse of the Larsen B and Wilkins ice shelves in the 2000s has had similar consequences: an abrupt acceleration in the rate local glaciers drain into the ocean.

Though the Antarctic Peninsula is plastered in snow and ice, the region is losing ice at an increasing rate. Credit: Pippa Whitehouse, University of Durham

This new knowledge will help us better predict sea level rise in the future. In 2014 the intergovernmental panel on climate change (IPCC) published its fifth assessment report, which includes modelled projections of Antarctica's contribution to sea level rise over the century. By mapping our measured sea level contribution on top of these projections, we found that our previous assessment of Antarctic sea level contribution, which measured ice loss until 2012, was tracking the IPCC's lowest projection. 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. This amounts to an additional 15cm in global sea level rise from Antarctica alone by 2100.

We have long suspected that changes in Earth's climate will affect the polar ice sheets. The rapid increase in Antarctic ice loss and consequent sea level rise we have measured over the past 25 years are a clear indicator of climate change. Limiting global warming to 2℃ by 2100, as set by the Paris Agreement, looks increasingly unlikely. The rate at which ice losses from Antarctica will increase in response to a warming world remains uncertain. It is important, now more than ever, that we continue to use satellites to monitor Antarctica in order to better prepare ourselves for the challenges ahead.

Explore further: Antarctica ramps up sea level rise

Related Stories

Antarctica ramps up sea level rise

June 13, 2018

Ice losses from Antarctica have increased global sea levels by 7.6 mm since 1992, with two fifths of this rise (3.0 mm) coming in the last five years alone.

Alarming projections for polar ice sheets

March 2, 2018

Drawing on international research, Professor Tim Naish from Victoria University of Wellington's Antarctic Research Centre took the second Pacific Climate Change Conference, co-hosted by Victoria and the Secretariat of the ...

Satellites track vanishing Antarctic ice

June 13, 2018

Monitoring Antarctica from space has revealed how its ice is being lost to the oceans, providing crucial insight into the continent's response to a warming climate.

Why remote Antarctica is so important in a warming world

December 4, 2017

Ever since the ancient Greeks speculated a continent must exist in the south polar regions to balance those in the north, Antarctica has been popularly described as remote and extreme. Over the past two centuries, these factors ...

More ice loss through snowfall on Antarctica

December 12, 2012

Stronger snowfall increases future ice discharge from Antarctica. Global warming leads to more precipitation as warmer air holds more moisture – hence earlier research suggested the Antarctic ice sheet might grow under ...

Recommended for you


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (2) Jun 17, 2018
Antarctic ice melting faster than ever versus Is Antarctica losing or gaining ice? versus NASA glaciologist Jay Zwally: 'Antarctica is gaining ice' versus The West Antarctic Ice Sheet Seems to Be Good at Collapsing: study finds it shrank dramatically even when Earth was not as warm as today.
So - what actually happens there? In my theory the global warming is of geothermal origin and it melts the Antarctic ice from bottom - not from surface. It just applies to west Antarctic bays exposed to ocean water from bellow, whereas the ice may grow at another places.
1 / 5 (2) Jun 17, 2018
BTW The similar event did happen many times in the past already, because the heating of earth crust is driven by cosmology, by density of dark matter affecting the speed of decay and transmutation of radioactive elements within soil and marine water in particular.
5 / 5 (1) Jun 21, 2018
@ZoeBell, why don't you have a Nobel prize? Because if you actually have evidence of dark matter interacting with baryons, and you can both prove that CO2 has nothing to do with global warming AND that your geothermal theory is correct, you're undoubtedly the single most accomplished scientist of all time.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.