Uncorking East Antarctica yields unstoppable sea-level rise

May 05, 2014
Credit: Newcastle University

The melting of a rather small ice volume on East Antarctica's shore could trigger a persistent ice discharge into the ocean, resulting in unstoppable sea-level rise for thousands of years to come. This is shown in a study now published in Nature Climate Change by scientists from the Potsdam Institute for Climate Impact Research (PIK). The findings are based on computer simulations of the Antarctic ice flow using improved data of the ground profile underneath the ice sheet.

"East Antarctica's Wilkes Basin is like a bottle on a slant," says lead-author Matthias Mengel, "once uncorked, it empties out." The basin is the largest region of marine ice on rocky ground in East Antarctica. Currently a rim of ice at the coast holds the ice behind in place: like a cork holding back the content of a bottle. While the air over Antarctica remains cold, warming oceans can cause ice loss on the coast. Ice melting could make this relatively small cork disappear – once lost, this would trigger a long term sea-level rise of 300-400 centimeters. "The full would ultimately be up to 80 times bigger than the initial melting of the ice cork," says co-author Anders Levermann.

"Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk," says Levermann, who is head of PIK's research area Global Adaptation Strategies and a lead-author of the sea-level change chapter of the most recent scientific assessment report by the Intergovernmental Panel on Climate Change, IPCC. This report, published in late September, projects Antarctica's total sea level contribution to be up to 16 centimeters within this century. "If half of that occurred in the ice-cork region, then the discharge would begin. We have probably overestimated the stability of East Antarctica so far," says Levermann.

Emitting greenhouse-gases could start uncontrollable ice-melt

Melting would make the grounding line retreat – this is where the ice on the continent meets the sea and starts to float. The rocky ground beneath the ice forms a huge inland sloping valley below sea-level. When the grounding line retreats from its current position on a ridge into the valley, the rim of the ice facing the ocean becomes higher than before. More ice is then pushed into the sea, eventually breaking off and melting. And the warmer it gets, the faster this happens.

Complete discharge from the affected region in East Antarctica takes five thousand to ten thousand years in the simulations. However, once started, the discharge would slowly but relentlessly continue until the whole basin is empty, even if climate warming stopped. "This is the underlying issue here", says Matthias Mengel. "By emitting more and more greenhouse gases we might trigger responses now that we may not be able to stop in the future." Such extensive sea level rise would change the face of planet Earth – coastal cities such as Mumbai, Tokyo or New York are likely to be at risk.

Explore further: West Antarctic ice sheet formed earlier than thought

More information: Mengel, M., Levermann, A. (2014): Ice plug prevents irreversible discharge from East Antarctica. Nature Climate Change (online) DOI: 10.1038/NCLIMATE2226

Related article: Levermann, A., Bamber, J., Drijfhout, S., Ganopolski, A., Haeberli, W., Harris, N.R.P., Huss, M., Krüger, K., Lenton, T., Lindsay, R.W., Notz, D., Wadhams, P., Weber, S. (2012): Potential climatic transitions with profound impact on Europe - Review of the current state of six 'tipping elements of the climate system'. Climatic Change 110 (2012), 845-878, DOI: 10.1007/s10584-011-0126-5

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dramamoose
2.2 / 5 (6) May 05, 2014
Takes five to ten thousand years, though. Look at what we've achieved in terms of science in merely the last 100 years. I have no doubt that within at least 1000 years we could develop technology to either lower sea levels, stop the draining of the ice basin, or at the very least relocate everything that's lower than 10ft underwater.
TegiriNenashi
1.6 / 5 (7) May 05, 2014
Have the authors bother to check southern hemisphere temperature history and correlated near record sea ice anomaly? When there is excess of journals devoted to the problem then warranted (Nature Climate Change, Climatic Change, ...) they start generating fairy tales.
Aedh
4.2 / 5 (5) May 05, 2014
The increasing growth of the sea in the winter season in the Antarctic is showing contradictory results. Antarctica is growing upward but this does NOT CONTRADICT global warming. The growth is very slow compared to the loss of ice in the Arctic.In the Journal of Climatology a new study suggested that about 80 % of the Antarctic sea ice growth can be explained by the alterations in the existing winds around the frozen continent. Jinlun Zhang, researcher from the University of Washington, said that about 80% of the increase is due to the alterations in the winds prevailing in the frozen continent. However, the remaining 20% is the outcome of the alterations in the circulation of the ocean. The researcher published his views in the Journal of Climatology.
TegiriNenashi
1.8 / 5 (5) May 05, 2014
Nothing contradicts GW. Neither temperature station data
http://www.nerc-b...rend.pdf
nor satellite observations of inconveniently growing sea ice. All you can suggest is some obscure reference to some lame explanation supporting your faith. At this point you guys are laughing stock of science community. Did ""John Mercer effect" taught you any lesson?
howhot2
4 / 5 (8) May 05, 2014
Considering that CO2 lingers in the atmosphere for over 1000 years, and as lingers it acts as a green house gas, trapping heat. We are exponentially increasing CO2 levels and have in all likelihood, passed a point where we could reverse global warming. 2030 to 2040 we really should see the beginning of mankind's doom. The Arctic should be ICE free and Greenland will be dumping it's freshwater reserves into the ocean changing it's salinity in such a way the ocean currents could change. Extinction events should become more frequent as species die of from climate extremes. Then the Anarctic ICE will drops it's load in the ocean too; giving a 27 meter rise in ocean levels! Wow.

But don't worry, you will still be able to buy a gallon of gas for under 4 bucks thanks to all of the tar sands mined up north. I love the future. It is going to be sooo messed up!

gregor1
2.3 / 5 (3) May 06, 2014
Another totally bogus paper from PIK. There is no evidence for this at all. It is entirely based on computer simulations. Any one interested should read this
http://notrickszo...nlikely/
PinkElephant
5 / 5 (3) May 06, 2014
@TegiriNenashi,
Nothing contradicts GW. Neither temperature station data
http://www.nerc-b...rend.pdf
nor satellite observations of inconveniently growing sea ice.
And especially not satellite observations of decreasing overall Antarctic ice mass:

http://www.skepti...iate.htm

That's because GW is reality, and nothing contradicts reality. After so many years on this site, you ought to be getting a clue. The fact that you're not, indicates that you're physiologically incapable of getting a clue.

My condolences...