Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

More ice in a warming world

16.12.2014

Antarctic sea-ice coverage has increased over the past few decades. A new study explains why this is the case, why models do not capture the increase and what humans might have to do with the expanding ice cover.

In September 2014, Antarctic sea ice covered more than 20 million square kilometers for the first time since the beginning of continuous satellite measurements in 1979. This maximum extent continues an overall increase of Antarctic sea ice that has puzzled scientists and the general public alike, in particular given the ongoing overall warming of our planet that simultaneously causes Arctic sea ice to retreat rapidly.


Cold southerly winds push sea ice away from the Antarctic coast, leading to new ice formation in the open water (polynya) along the coast. Satellite image by Terra-MODIS on October 23, 2001

Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC


Decadal trends of annual mean sea-ice concentration (shading) and drift (vectors) derived from satellite images.

Haumann et al., 2014, Geophys. Res. Lett

In a new study published this week in Geophysical Research Letters, scientists from the Max Planck Institute for Meteorology (MPI-M) in Germany explain the underlying cause of the long-term Antarctic sea-ice increase and analyze why climate models fail to reproduce it. „There is primarily one thing you need to get right if you want to model Antarctic sea ice: The wind pattern“, explains Alexander Haumann, lead author of the new study.

„We are primarily talking about regions with winter-time temperatures far below freezing here, and even with the ongoing warming, there is still a lot of ice growth in the ocean around Antarctica. Forced by strong winds, this sea ice is sometimes transported over more than a thousand kilometers. So if you want to know where it goes and which area it covers, you need to understand how it's being pushed around by the winds. “

And these winds have changed over the past decades. „We see a stronger off-shore component of wind patterns in particular in the Ross Sea, which is the sector of Antarctica that opens towards the Pacific. There, the winds have changed such that they blow the ice further away from the coast where new ice continuously forms“, explains Haumann's colleague Dirk Notz who leads the Sea-ice research group at MPI-M. While this was suspected also by earlier studies, the new study now shows this relationship to play the main role in ice coverage until today. „Where the winds blow more strongly away from the Antarctic continent, the ice cover increases because the ice is further blown to the north and the ocean refreezes in the south. It's as simple as that. “

Two questions then of course remain: Why have the winds changed? And why do models not capture these changes? The new study addresses both these questions. „The changing wind patterns are caused by lower surface pressure in some areas around Antarctica. In our model simulations, we get such lower surface pressure if we include both the effect of the ozone hole and the increase in greenhouse gas concentration. The ozone hole cools the high atmosphere over Antarctica, while the greenhouse gases warm the lower atmosphere. In combination, this can explain a change of the wind pattern, but we’re not sure yet whether this is also the main driver of the changes in the real world.“, says Hauke Schmidt, who leads the Middle and Upper Atmosphere research group at MPI-M.

But even though the model simulates a lowering of the surface pressure, it does not get the ice increase. Also this the scientists now understand: They suspect that the model does not capture the influence of the smaller scale topography around the continent and surface processes over ice and snow accurately enough. These processes influence the surface-pressure distribution and hence the direction of the wind. “In our model, the pressure changes such that the wind primarily blows stronger parallel to the coast line rather than away from it. Once this is better represented in the model, we should get better simulations of the sea-ice trend”, concludes Haumann.

So the scientists have understood why the sea ice increases and why their model does not capture it. Now they work on improving the atmospheric circulation around the continent, trusting that this will eventually allow them to reproduce the observed sea-ice increase in their model. Then the puzzle of Antarctic sea ice would fully be solved.

Original Publication
Haumann, F.A., D. Notz, and H. Schmidt (2014), Anthropogenic influence on recent circulation-driven Antarctic sea-ice changes, Geophys. Res. Lett., doi: 10.1002/2014GL061659

Contact:

Dr. Alexander Haumann,
now at ETH Zurich,
Phone: +41 44 6325786
Email: alexander.haumann@usys.ethz.ch,

Dr. Dirk Notz
Max Planck Institute for Meteorology
Phone: +49 (0) 40 41173 163
Email: dirk.notz@mpimet.mpg.de

Dr. Hauke Schmidt
Max Planck Institute for Meteorology
Phone: +49 (0) 40 41173 405
Email: hauke.schmidt@mpimet.mpg.de

Dr. Annette Kirk | Max-Planck-Institut für Meteorologie
Further information:
http://www.mpimet.mpg.de

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>