Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Andrill demonstrates climate warming affects Antarctic ice sheet stability

20.03.2009
A five-nation scientific team has published new evidence that even a slight rise in atmospheric concentrations of carbon dioxide, one of the gases that drives global warming, affects the stability of the West Antarctic Ice Sheet (WAIS).

The massive WAIS covers the continent on the Pacific side of the Transantarctic Mountains. Any substantial melting of the ice sheet would cause a rise in global sea levels.

The research, which was published in the March 19 issue of the journal Nature, is based on investigations by a 56-member team of scientists conducted on a 1,280-meter (4,100-foot)-long sedimentary rock core taken from beneath the sea floor under Antarctica's Ross Ice Shelf during the first project of the ANDRILL (ANtarctic geological DRILLing) research program--the McMurdo Ice Shelf (MIS) Project.

The National Science Foundation (NSF), which manages the U.S. Antarctic Program (USAP), provided about $20 million in support of the ANDRILL program. The other ANDRILL national partners contributed an additional $10 million in science and logistics support.

"The sedimentary record from the ANDRILL project provides scientists with an important analogue that can be used to help predict how ice shelves and the massive WAIS will respond to future global warming over the next few centuries," said Ross Powell, a professor of geology at Northern Illinois University.

"The sedimentary record indicates that under global warming conditions that were similar to those projected to occur over the next century, protective ice shelves could shrink or even disappear and the WAIS would become vulnerable to melting," Powell said. "If the current warm period persists, the ice sheet could diminish substantially or even disappear over time. This would result in a potentially significant rise in sea levels."

ANDRILL--which involves scientists from the United States, New Zealand, Italy and Germany--refines previous findings about the relationship between atmospheric carbon dioxide concentration, atmospheric and oceanic temperatures, sea level rise and natural cycles in Earth's orbit around the Sun, through the study of sediment and rock cores that are a geological archive of past climate.

The dynamics of ice sheets, including WAIS, are not well understood, and improving scientists' comprehension of the mechanisms that control the growth, melting and movements of ice sheets was one of NSF's research priorities during the International Polar Year (IPY). The IPY field campaign, which officially ended March 2009, has been an intense scientific campaign to explore new frontiers in polar science, improve our understanding of the critical role of the polar regions in global processes, and educate students, teachers, and the public about the polar regions and their importance to the global system. NSF was the lead agency for U.S. IPY efforts.

The cores retrieved by ANDRILL researchers have allowed them to peer back in time to the Pliocene era, roughly 2 million to 5 million years ago. During that era, the Antarctic was in a natural climate state that was warmer than today and atmospheric carbon dioxide levels were higher. Data from the cores indicate the WAIS advanced and retreated numerous times in response to forcing driven by these climate cycles.

Powell and Tim Naish, director of Victoria University of Wellington's Antarctic Research Centre, served as co-chief scientists of the 2006-2007 ANDRILL project that retrieved the data and are lead authors in one of two companion studies published in Nature.

Naish said the new information gleaned from the core shows that changes in the tilt of Earth's rotational axis has played a major role in ocean warming that has driven repeated cycles of growth and retreat of the WAIS for the period in Earth's history between 3 million and 5 million years ago.

"It also appears that when atmospheric carbon dioxide concentrations reached 400 parts per million around four million years ago, the associated global warming amplified the effect of the Earth's axial tilt on the stability of the ice sheet," he said.

"Carbon dioxide concentration in the atmosphere is again approaching 400 parts per million," Naish said. "Geological archives, such as the ANDRILL core, highlight the risk that a significant body of permanent Antarctic ice could be lost within the next century as Earth's climate continues to warm. Based on ANDRILL data combined with computer models of ice sheet behavior, collapse of the entire WAIS is likely to occur on the order of 1,000 years, but recent studies show that melting has already begun."

The second ANDRILL study in Nature--led by David Pollard of Pennsylvania State University and Rob DeConto from University of Massachusetts--reports results from a computer model of the ice sheets. The model shows that each time the WAIS collapsed, some of the margins of the East Antarctic Ice Sheet also melted, and the combined effect was a global sea level rise of 7 meters above present-day levels.

Whether the beginnings of such a collapse could start 100 years from now or within the next millennium is hard to predict and depends on future atmospheric CO2 levels, the researchers said. However, the new information from ANDRILL contributes a missing piece of the puzzle as scientists try to refine their predictions of the effects of global warming.

The most recent report of the Intergovernmental Panel on Climate Change (IPCC) noted that because so little is understood about ice sheet behavior it is difficult to predict how ice sheets will contribute to sea level rise in a warming world. The behavior of ice sheets, the IPCC report said, is one of the major uncertainties in predicting exactly how the warming of the globe will affect human populations.

"From these combined data modeling studies, we can say that past warming events caused West Antarctic ice shelves and ice grounded below sea level to melt and disappear. The modeling suggests these collapses took one to a few thousand years," Pollard said.

Pollard and DeConto also underscored the role of ocean temperatures in melting of the ice.

"It's clear from our combined research using geological data and modeling that ocean temperatures play a key role," DeConto said. "The most substantial melting of protective ice shelves comes from beneath the ice, where it is in contact with seawater. We now need more data to determine what is happening to the underside of contemporary ice shelves."

Peter West | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Earth Sciences:

nachricht Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds
25.07.2017 | University of Illinois at Urbana-Champaign

nachricht NASA flights gauge summer sea ice melt in the Arctic
25.07.2017 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>