Will Antarctica go away in time?

02.11.2015 20:00

"Eternal ice is not eternal": West Antarctica could melt completely

Mareike Schodder Press and public relations
Potsdam Institute for Climate Impact Research

ATTENTION BLOCKING PERIOD until Monday, November 2nd, 8 p.m. German time

Scientists at the Potsdam Institute for Climate Impact Research have now calculated that the huge ice sheet in western Antarctica could disappear completely if the comparatively tiny Amundsen Basin there became unstable. If all of this ice gets into the ocean, the sea level rises by around three meters. A few studies published a few months ago indicate that this area of ​​the ice continent has already lost its stability - that would actually tip the first element of the Earth system.

The new publication shows for the first time the consequences of such a development. A few decades of ocean warming can trigger a loss of ice lasting centuries and millennia, according to the computer simulations.

"What we call the eternal ice of the Antarctic unfortunately turns out to be by no means eternal," says Johannes Feldmann, lead author of the study that is now appearing in the 'Proceedings' of the US National Academy of Sciences (PNAS). “If the natural state of the ice masses is disturbed, and that's exactly what happens today, they react in a non-linear way: after a long period of time without any major changes, their stability collapses fairly quickly.” This is why one speaks of tipping elements: they close strongly pushed, they fall into a different state. This also applies to the Amazon rainforest, for example, and the Indian monsoon system. In the Antarctic, the natural flow of ice into the ocean then increases significantly and permanently.

"A few decades of melting initiate a millennium change"

The warming of the ocean slowly melts from below the ice shelves protruding from the mainland into the sea and floating up. Much of the ice in West Antarctica rests on a bed of rock that is below sea level. Loss of ice at the edges leads to the fact that the touchdown line of the land ice shifts bit by bit inland. Because the ground here falls instead of rises, an ever thicker edge of the ice is exposed to the warmer sea water - which further accelerates the loss of ice.

"In our simulations, 60 years of melting at the rate that can be observed today is sufficient to trigger a process of ice loss that can no longer be stopped and that lasts for thousands of years," explains Feldmann. This would ultimately lead to a rise in sea level of at least three meters. “Of course, this takes place over a very long period of time,” says Feldmann. "But it starts with us."

The greenhouse gas factor

"So far we lack the evidence to be able to say whether the loss of stability of the Amundsen ice was triggered by greenhouse gases and the corresponding global warming," says co-author Anders Levermann, who worked as a sea level expert on the most recent report by the IPCC Has. "What is clear, however, is that further greenhouse gas emissions increase the risk of a collapse in West Antarctica - and with it that of an unstoppable rise in sea levels."

“You don't have to be afraid of rising sea levels, but it is something you have to take care of,” says Levermann. “The sea level is rising slowly, but in the process it is destroying our human heritage; Coastal metropolises like Hamburg and New York, which will bear parts of our cultural heritage of the future - if we don't reduce CO2 emissions quickly. "

Article: Feldmann, J., Levermann, A. (2015): Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin. Proceedings of the National Academy of Sciences (PNAS, Online Early Edition) [DOI: 10.1073 / pnas.1512482112]

Web link to the article as soon as it is published: www.pnas.org/cgi/doi/10.1073/pnas.1512482112

Contact for further information:
Potsdam Institute for Climate Impact Research, press office
Phone: +49 (0) 331 288 2507
Email: [email protected]
Twitter: @PIK_Klima

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