Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study: How stable is the West Antarctic Ice Sheet?

09.02.2016

Exceeding critical temperature limits in the Southern Ocean may cause the collapse of ice sheets and a sharp rise in sea levels

A future warming of the Southern Ocean caused by rising greenhouse gas concentrations in the atmosphere may severely disrupt the stability of the West Antarctic Ice Sheet. The result would be a rise in the global sea level by several metres.


Frozen meltwater (shelf ice edge, Larsen A, Weddell Sea)

Photo: W. Arntz / Alfred Wegener Institute

A collapse of the West Antarctic Ice Sheet may have occurred during the last interglacial period 125,000 years ago, a period when the polar surface temperature was around two degrees Celsius higher than today. This is the result of a series of model simulations which the researchers of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), have published online in the journal Geophysical Research Letters.

The Antarctic and Greenland are covered by ice sheets, which together store more than two thirds of the world's freshwater. As temperatures rise, ice masses melt; in consequence the global sea level rises and threatens the coastal regions.

According to scientific findings, the Antarctic already today contributes to the annual sea level rise with 0.4 millimetres. However, the most recent world climate assessment report (IPCC 2013) pointed out that the development of the ice masses in the Antarctic is not yet sufficiently understood. Climate modellers of the Alfred Wegener Institute have therefore analysed the changes to the Antarctic Ice Sheet in the last interglacial period and applied their findings to future projections.

"Both, for the last interglacial period around 125,000 years ago and for the future our study identifies critical temperature limits in the Southern Ocean: If the ocean temperature rises by more than two degrees Celsius compared with today, the marine-based West Antarctic Ice Sheet will be irreversibly lost. This will then lead to a significant Antarctic contribution to the sea level rise of some three to five metres", explains AWI climate scientist Johannes Sutter. This rise, however, will only occur if climate change continues as it has up to now. The researchers make these assessments based on model simulations.

"Given a business-as-usual scenario of global warming, the collapse of the West Antarctic could proceed very rapidly and the West Antarctic ice masses could completely disappear within the next 1,000 years", says Johannes Sutter, the study's main author, who has just completed his doctoral thesis on this topic. "The core objective of the study is to understand the dynamics of the West Antarctic during the last interglacial period and the associated rise in sea level. It has been a mystery until now how the estimated sea level rise of a total of about seven metres came about during the last interglacial period. Because other studies indicate that Greenland alone could not have done it", Prof Gerrit Lohmann, the head of the research project, adds.

The new findings on the dynamics of the ice sheet allow conclusions to be drawn about how the ice sheet might behave in the wake of global warming. According to model calculations, the ice masses shrink in two phases. The first phase leads to a retreat of the ice shelves, ice masses that float on the ocean in the coastal area of the Antarctic stabilising the major glacier systems of the West Antarctic. If the ice shelves are lost, the ice masses and glaciers of the hinterland accelerate and the ice flow into the oceans increases. As a result, the sea level rises, the grounding line retreats, leading to a further floatation of the grounded ice masses with a progressing acceleration and retreat of the glaciers. These will achieve a stable intermediate state only once - put simply - a mountain ridge under the ice temporarily slows down the retreat of the ice masses.

If the ocean temperature continues to rise or if the grounding line of the inland ice reaches a steeply ascending subsurface, then the glaciers will continue to retreat even if the initial stable intermediate state has been reached. Ultimately, this leads to a complete collapse of the West Antarctic Ice Sheet. "Two maxima are also apparent in the reconstructions of the sea level rise in the last interglacial period. The behaviour of the West Antarctic in our newly developed model could be the mechanistic explanation for this", says a delighted Johannes Sutter.

The climate scientists used two models in their study. A climate model that includes various Earth system components such as atmosphere, oceans and vegetation, and a dynamic ice sheet model that includes all basic components of an ice sheet (floating ice shelves, grounded inland ice on the subsurface, the movement of the grounding line). Two different simulations were used with the climate model for the last interglacial period to feed the ice sheet model with all the necessary climate information.

"One reason for the considerable uncertainties when it comes to projecting the development of the sea level is that the ice sheet does not simply rest on the continent in steady state, but rather can be subject to dramatic changes", according to the AWI climate scientists, emphasising the challenges involved in making good estimates. "Some feedback processes, such as between the ice shelf areas and the ocean underneath, have not yet been incorporated into the climate models. We at the AWI as well as other international groups are working on this full steam." Improving our understanding of the systematic interaction between climate and ice sheets is crucial in order to answer one of the central questions of current climate research and for future generations: How steeply and, above all, how quickly can the sea level rise in the future?

Original paper:

Johannes Sutter, Paul Gierz, Klaus Grosfeld, Malte Thoma, Gerrit Lohmann: Ocean temperature thresholds for Last Interglacial West Antarctic Ice Sheet collapse. Geophysical Research Letters 2016. DOI: 10.1002/2016GL067818
http://onlinelibrary.wiley.com/doi/10.1002/2016GL067818/full

Notes for Editors:

Your scientific contact persons are Johannes Sutter (e-mail: Johannes.Sutter(at)awi.de), Professor Gerrit Lohmann, tel. +49 (0)471 4831-1758 (e-mail: Gerrit.Lohmann(at)awi.de) and Dr Klaus Grosfeld, tel. +49 (0)471 4831-1765 (e-mail: Klaus.Grosfeld(at)awi.de).

Please find printable images in the online version of this press release: http://www.awi.de/nc/en/about-us/service/press.html

Your contact person in the Communications and Media Department is Dr Folke Mehrtens, tel. +49 (0)471 4831-2007 (e-mail: medien(at)awi.de).

The Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) conducts research in the Arctic, Antarctic and oceans of the high and mid-latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctica. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Ralf Röchert | idw - Informationsdienst Wissenschaft
Further information:
http://www.awi.de

More articles from Studies and Analyses:

nachricht Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung

nachricht Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>