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

More articles from Earth Sciences:

nachricht Filling the gap: High-latitude volcanic eruptions also have global impact
20.11.2017 | Institute of Atmospheric Physics, Chinese Academy of Sciences

nachricht Antarctic landscape insights keep ice loss forecasts on the radar
20.11.2017 | University of Edinburgh

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 “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>