Rising temperatures in the oceans caused the melting of Antarctic ice sheets 120,000 years ago and, as a result, extreme sea-level rise, according to the study led by Chris Turney of the University of New South Wales in Australia. Sea levels rose by more than 3 meters over several centuries. “Not only did we lose a lot of the West Antarctic Ice Sheet, but this happened very early during the Last Interglacial,” says Turney. “The melting was likely caused by less than 2 °C ocean warming – and that's something that has major implications for the future, given the ocean temperature increase and West Antarctic melting that’s happening today,” Turney says.
Through its sophisticated detective work analyzing data from climate history, the study confirms that the West Antarctic ice sheet is close to a stability tipping point. Earlier studies based on modern observational data and climate models had concluded that the tipping point has already been exceeded today and the ice sheet has become unstable.
"The better we understand the climate of the past, the better we can deduce what this means for the future. Here, the analysis of climate history reveals that we would probably completely lose the West Antarctic Ice Sheet in a two-degree Celsius warmer world," explains Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research, one of the authors of the study. “While we may have triggered the collapse of the West Antarctic Ice Sheet already, the speed of the ice loss can still be limited by limiting global warming. Once more, this underlines the importance of the Paris Climate Agreement with the aim to keep global warming to well below 2 degrees Celsius, or better still 1.5°C."
Link to the press release by the University of New South Wales in Australia with more information:
https://newsroom.unsw.edu.au/news/science-tech/ancient-antarctic-ice-melt-increased-sea-levels-3-metres-%E2%80%93-and-it-could-happen
Article:
Chris S. M. Turney, Christopher J. Fogwill, Nicholas R. Golledge, Nicholas P. McKay, Erik van Sebille, Richard T. Jones, David Etheridge, Mauro Rubino, David P. Thornton, Siwan M. Davies, Christopher Bronk Ramsey, Zoë A. Thomas, Michael I. Bird, Niels C. Munksgaard, Paul G. Albert, Andres Rivera, Tas von Ommen, Mark Curran, Andrew Moy, Stefan Rahmstorf, Kenji Kawamura, Claud-Dieter Hillenbrand, Michael E. Weber, Christina J. Manning, Jennifer Young, Alan Cooper (2020): Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica. PNAS
Link to the study at PNAS: www.pnas.org/cgi/doi/10.1073/pnas.1902469117
Examples of further PIK research on tipping elements, sea-level rise and Antarctica:
T. M. Lenton, J. Rockström, O. Gaffney, S. Rahmstorf, K. Richardson, W. Steffen, H. J. Schellnhuber (2019): Climate tipping points – too risky to bet against. Nature
https://www.nature.com/articles/d41586-019-03595-0
https://www.pik-potsdam.de/news/press-releases/climate-tipping-points-2013-too-risky-to-bet-against
A. Levermann & J. Feldmann (2019): Scaling of instability time-scales of Antarctic outlet glaciers based on one-dimensional similitude analysis, The Cryosphere 13. DOI: 10.5194/tc-13-1621-2019. https://www.the-cryosphere.net/13/1621/2019/tc-13-1621-2019.html
R. Winkelmann, A. Levermann, A. Ridgwell, K. Caldeira (2015): Combustion of available fossil-fuel resources sufficient to eliminate the Antarctic Ice Sheet, Science Advances 1. DOI:10.1126/sciadv.1500589. http://advances.sciencemag.org/content/1/8/e1500589
A. Dutton, A. E. Carlson, A. J. Long, G. A. Milne, P.U. Clark, R. DeConto, B. P. Horton, S. Rahmstof, M. E. Rayno (2015): Sea-level rise due to polar ice-sheet mass loss during past warm periods. Science 349. DOI: 10.1126/science.aaa4019 https://science.sciencemag.org/content/sci/349/6244/aaa4019.full.pdf
J. Feldmann, A. Levermann (2015): Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin. Proceedings of the Academy of Sciences 112. DOI 10.1073/pnas.1512482112.
https://www.pnas.org/content/early/2015/10/28/1512482112
Link to our press release on the study
M. Mengel, A. Levermann (2014): Ice plug prevents irreversible discharge from East Antarctica. Nature Climate Change. DOI: 10.1038/nclimate2226. https://www.nature.com/articles/nclimate2226
Link to our press release on the study
