Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The shield is crumbling

09.02.2016

Over the past 20 years, many ice shelves in Antarctica have shrunk and some have disappeared entirely. This has resulted in a significant acceleration of many Antarctic glaciers, contributing to rising sea levels. Dr. Johannes Fürst from the Institute of Geography at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) has used a complex model to show for the first time at what point the “buttressing” role of ice shelves is impaired due to their decline. The results of Dr. Fürst's research, carried out in collaboration with Antarctic experts from Laboratoire de Glaciologie et Géophysique de l'Environnement in Grenoble, France, have been published in the journal Nature Climate Change*.

Antarctica is surrounded by huge ice shelves. The largest of these, the Ross Ice Shelf, has an area comparable to the size of Spain. These ice shelves are several hundred metres thick and float on the surface of the sea, towering above the water.


Calving front of the Fleming Glacier which fed into the Wordie Ice Shelf before it collapsed in the late 1980s. One can discern the high calving activity characterising the post-collapse period.

Photo: Matthias Braun

They are firmly linked to glaciers and ice streams on mainland Antarctica. These ice shelves are naturally fed by upstream inflow from tributary glaciers which push the floating ice seawards. Away from the mainland, at the seaward fronts of these ice shelves, ice breaks off as vast icebergs which drift away. This loss of ice is usually compensated for by land ice flowing in to replace it. This natural balance prevailed for thousands of years.

Ice-shelf retreat since 1995

However, over the past 20 years, researchers observed the progressive retreat and break-up of ice shelves on the Antarctic Peninsula. In 1995, Larsen A Ice Shelf collapsed completely removing the ice-cover from an area the size of Berlin. Seven years later, the much larger Larsen B Ice Shelf broke apart. This disintegration had hardly any immediate effect on sea levels as the lost ice was already afloat.

However, upstream tributary glaciers flowing towards the ocean accelerated by up to eight times after the break-up events on Larsen A and B. 'In contrast to the situation in Greenland, the loss of inland ice in West Antarctica is not caused by melting. It is much too cold for that to happen,' Johannes Fürst explains. 'The decrease is due to the glaciers there flowing into the sea at a faster rate than 20 years ago. This is what we call dynamic ice loss.'

Long-term sea-level rise

If all the ice shelves surrounding Antarctica were to collapse, this would result in rapid dynamic loss of inland ice, which would entail an elevated Antarctic contribution to sea-level rise for decades to come. Originally working at the LGGE in Grenoble, Johannes Fürst has now spent several years investigating how the presence of ice shelves exerts control on the upstream glacier dynamics. ‘As ice shelves continuously lose ice by calving, it is essential to known how far the recession of ice shelves may progress before the buttressing potential is reduced,' he says.

The West-Antarctic underbelly

For the whole of Antarctica, ice velocity data inferred from satellite images, including images of the European Space Agency (ESA), and airborne observations on ice thickness were analysed by Fürst, using an Elmer/Ice flow model developed in a collaborative effort between France (LGGE) and Finland (CSC). This enabled him to calculate that about 13 per cent of the total ice-shelf area contains so-called passive shelf ice. 'Passive shelf ice is the part of the floating ice body which provides no additional buttressing,' he explains.

'It is this portion which, when lost by calving, will not trigger an instant velocity increase.' His analysis reveals contrasting results across the continent. Along the coast of Queen Maud Land, ice shelves still have a relatively large and ‘healthy’ portion of passive ice. They are thus considered rather stable, for now. In the Bellingshausen and Amundsen Seas, this portion is much smaller. For some ice shelves, it is already almost absent.

'We expect that further ice-shelf retreat there will instantly produce dynamic changes, which may well give rise to increased ice outflow from the mainland,' Fürst explains. 'This is worrying because it is in this region that we have observed the highest rates of ice-shelf thinning over the past two decades and dynamic ice loss in the inland areas upstream.'

*Nature Climate Change: The safety band of Antarctic ice shelves, Johannes Jakob Fürst, Gaël Durand, Fabien Gillet-Chaulet, Laure Tavard, Melanie Rankl, Matthias Braun and Olivier Gagliardini. DOI: http://dx.doi.org/10.1038/NCLIMATE2912

Contact:
Dr. Johannes Fürst
Phone: +49 9131 8526680
johannes.fuerst@fau.de

Dr. Susanne Langer | idw - Informationsdienst Wissenschaft
Further information:
http://www.fau.de/

More articles from Earth Sciences:

nachricht World’s oldest known oxygen oasis discovered
18.01.2018 | Eberhard Karls Universität Tübingen

nachricht A close-up look at an uncommon underwater eruption
11.01.2018 | Woods Hole Oceanographic Institution

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>