Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Climate scientists discover new weak point of the Antarctic ice sheet

10.05.2012
The Filchner-Ronne Ice Shelf fringing the Weddell Sea, Antarctica, may start to melt rapidly in this century and no longer act as a barrier for ice streams draining the Antarctic Ice Sheet.

These predictions are made by climate researchers of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association in the coming issue of the British science magazine “Nature“. They refute the widespread assumption that ice shelves in the Weddell Sea would not be affected by the direct influences of global warming due to the peripheral location of the Sea.


Edge of the Filchner-Ronne Ice Shelf in the Weddell Sea, Photo: Ralph Timmermann, Alfred Wegener Institute

The results of the climate modelers from the Alfred Wegener Institute will come as a surprise to the professional world with the majority of experts assuming that the consequences of global warming for Antarctica would be noticeable primarily in the Amundsen Sea and therefore in the western part of Antarctica. “The Weddell Sea was not really on the screen because we all thought that unlike the Amundsen Sea its warm waters would not be able to reach the ice shelves. But we found a mechanism which drives warm water towards the coast with an enormous impact on the Fichner-Ronne Ice Shelf in the coming decades“, says Dr. Hartmut Hellmer, oceanographer at the Alfred Wegener Institute and lead author of the study.

Using different model calculations, he and his colleagues Dr. Frank Kauker, Dr. Ralph Timmermann and Dr. Jürgen Determann as well as Dr. Jamie Rae from Met Office Hadley Centre, U.K., demonstrate that as a result of a chain reaction large ice masses could presumably slide into the ocean within the next six decades.

This chain reaction is triggered by rising air temperatures above the southeastern Weddell Sea. “Our models show that the warmer air will lead to the currently solid sea ice in the southern Weddell Sea becoming thinner and therefore more fragile and mobile in a few decades“, says Frank Kauker. If this happens, fundamental transport processes will change. “This will mean that a hydrographic front in the southern Weddell Sea will disappear which has so far prevented warm water from getting under the ice shelf. According to our calculations, this protective barrier will disintegrate by the end of this century“, explains Hartmut Hellmer.

An inflow of warmer water beneath the Filchner-Ronne Ice Shelf will melt the ice from below. “We expect the greatest melting rates near the so-called grounding line, the zone in which the ice shelf settles on the sea floor at the transition to the glacier. At this point the Filchner-Ronne Ice Shelf is melting today at a rate of around 5 metres per year. By the turn of the next century the melt rates will rise to up to 50 metres per year“, says Hellmer’s colleague Jürgen Determann.

How the ice streams behind will react in the event of a melt of such enormous proportions is currently being investigated by Jürgen Determann. One thing is obvious, however: “Ice shelves are like corks in the bottles for the ice streams behind them. They reduce the ice flow because they lodge in bays everywhere and rest on islands. If, however, the ice shelves melt from below, they become so thin that the dragging surfaces become smaller and the ice behind them starts to move“, explains Hartmut Hellmer. "If the high melting rates are completely compensated by inland ice flow, this loss in mass would correspond to an additional rise in global sea level of 4.4 millimetres per year", adds Jürgen Determann. According to the latest estimates based on remote sensing data, global sea level rose for the period 2003-2010 at a rate of 1.5 millimetres per year due to melting of glaciers and ice shelves. This occurs in addition to the 1.7 millimetres per year due to thermal expansion of the oceans.

The forecasts of the current study are based on independent calculations of the ocean models BRIOS (Bremerhaven Regional Ice Ocean Simulations) and FESOM (Finite Element Sea Ice Ocean Model). The scientists used the atmospheric projections of the British Met Office Hadley Centre in Exeter as forcing data.

These included, for example, information on the future development of the wind and of the temperature in Antarctica. Hartmut Hellmer and his colleagues have thoroughly checked the model results for being realistic: “We started the BRIOS model in 1860 to see whether its results also represent the current situation. We found that this condition was satisfied. For example, the water temperatures for the Weddell Sea predicted by BRIOS are close to those we have actually measured in the recent past“, says Ralph Timmermann and adds: “The BRIOS model has been verified on many occasions in the past. It correctly predicts sea ice thickness, concentration, and drift as well as circulation patterns. And FESOM is well on the way to attaining BRIOS status. However, it has a far higher resolution, which is why we have to wait a long time until the computer has calculated several decades and more. BRIOS only needs less than a week for a century.“

The study was conducted as part of the EU-funded research programme “Ice2sea“. This project brings together scientists from 24 leading research institutions of the European Union and from Chile, Norway and Iceland. Together, the scientists aim for decoding the interactions between ice and climate and in this way facilitate more precise predictions about the effects of melting ice on sea level. More information on the Ice2sea project is available at www.ice2sea.eu

Embargoed until 09 May 2012, 1800 London time / 1900 Berlin time / 1300 US Eastern time

Original paper:
Hartmut H. Hellmer, Frank Kauker, Ralph Timmermann, Jürgen Determann, Jamie Rae: Twenty-first-century warming of a large Antarctic ice shelf cavity by a redirected coastal current. Nature 10 May 2012, Vol 485, page 225. DOI: 10.1038/nature11064

The Alfred Wegener Institute conducts research in the Arctic and Antarctic and in the high and mid-latitude oceans. The Institute coordinates German polar research and provides important infrastructure such as the research ice breaker Polarstern and research stations in the Arctic and Antarctic to the national and international scientific world. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Ralf Röchert | idw
Further information:
http://www.awi.de
http://www.awi.de/index.php?id=6227#21743

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>