Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UMass study reconsiders formation of Antarctic ice sheet

16.01.2003


Findings detailed in Jan. 16 issue of Nature; greenhouse gases implicated



A study by University of Massachusetts Amherst geoscientist Robert DeConto posits an alternative theory regarding why Antarctica suddenly became glaciated 34 million years ago. The study challenges previous thinking about why the ice sheet formed and holds ramifications for the next several hundred years as greenhouse gases continue to rise. DeConto, who collaborated with David Pollard of Pennsylvania State University, has published the findings in the Jan. 16 issue of the journal Nature. The work was funded by the National Science Foundation.

"Scientists have long known that Antarctica was not always covered in a sheet of ice. Rather, the continent was once highly vegetated and populated with dinosaurs, with perhaps just a few Alpine glaciers and small ice caps in the continental interior," DeConto explained. "In fact, the Antarctic peninsula is thought to have been a temperate rainforest." Previous research on microfossils and ocean chemistry had already revealed that the Antarctic ice sheet may have developed over a period of just 50,000 years or even less, "the flip of a light switch in geologic terms," said DeConto. The dramatic shift occurred at the cusp of the Eocene and Oligocene eras. "The question," noted DeConto, "is why did it happen then, and why did it happen so quickly?"


A theory put forth in the 1970s suggested that plate tectonics was the driving force in Antarctic glaciation. "Pangea, the ’supercontinent,’ was breaking up. Australia was pulling away to the north, opening an ocean channel known as the Tasmanian passage." Scientists theorized that as South America drifted away from the Antarctic Peninsula, the Drake passage opened. "This was thought to be the last barrier to an ocean current circumventing the continent. This current would have deflected warmer, northern waters and served to keep the continent chilled, and the Southern Oceans cool." The theory was known as "thermal isolation."

DeConto and Pollard wanted to determine how important the opening of the Southern Ocean passages actually was in the rapid glaciation of Antarctica. Among the factors they considered were: heat transport in the oceans; plate tectonics; carbon dioxide levels in the atmosphere; and orbital variation. "We wanted to know whether the opening of ocean gateways was the primary cause of the glaciation, or whether the change was due to a combination of factors," DeConto said.

The team turned to powerful computer technology in developing the new theory. Using computer simulations, the scientists essentially recreated the world of 34 million years ago, including a detailed topography of Antarctica and the placement of the drifting continents. Topography was particularly important, DeConto explained, because "if you have mountains that lift the snow into higher elevations, you have a better chance of maintaining snow all summer. This persistence is the key factor in formation of the ice sheet."

The team then plugged in the factors previously mentioned: plate tectonics, climate, orbital variation, and the Earth’s procession. The computer played out the scenario for 10 million years, taking into account the gradual drop in carbon dioxide in the atmosphere that is thought to have occurred in the Earth’s atmosphere during this period in Earth’s history. The scientists ran the simulation twice: "The two simulations were identical except in the second, a change in heat transport to replicate the opening of the Drake passage, to see how big an effect that gateway was."

"This research points out the value of fundamental climate research," said David Verardo, Director of the NSF’s Paleoclimate Program, which funded the research. "In short, DeConto and Pollard have shown, by using paleoclimatic models for a distant era, the power of atmospheric CO2 to produce rapid environmental change of gargantuan proportions. Furthermore, such effects can not be described by neat and simple regional patterns of variability."

"Our study indicates that carbon dioxide is the critical factor," DeConto said. "CO2 appears to be the factor that preconditions the system to become sensitive to other elements of the climate system. It was the first critical boundary and the determinant in the glaciation of the Antarctic continent.

"Carbon dioxide is a very important knob for changing climate, and is perhaps the fundamental control,"said DeConto. "This study indicates that the Earth’s climate is rapidly being pushed into a circumstance that hasn’t existed for a very long time; we’re returning to levels of carbon dioxide that have not been seen since before the Antarctic ice sheet." This doesn’t mean that Antarctica is going to melt in the next 100 years, he noted, "but it’s important to be aware that the CO2 levels are rising very quickly."


Note: Robert DeConto can be reached at 413-545-3426 or deconto@geo.umass.edu

Elizabeth Luciano | EurekAlert!
Further information:
http://www.umass.edu/

More articles from Earth Sciences:

nachricht Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation

nachricht Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>