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 Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland
15.11.2018 | Faculty of Science - University of Copenhagen

nachricht The unintended consequences of dams and reservoirs
14.11.2018 | Uppsala University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>