Antarctic subglacial mountain range the size of the Alps mapped
25 February 2009
Flying twin-engine light aircraft the equivalent of three trips around the globe and working in temperatures that averaged −30 degrees Celsius, an international team of scientists has not only verified the existence of a mountain range that is suspected to have caused the massive East Antarctic Ice Sheet to form, but also has created a detailed picture of the rugged landscape buried under more than four kilometres of ice.
“Working cooperatively in some of the harshest conditions imaginable, our seven-nation team has produced detailed images of last unexplored mountain range on Earth,” said Michael Studinger, of the Lamont-Doherty Earth Observatory at Columbia University, the co-leader of the United States portion of the Antarctica’s Gamburstev Province (AGAP) project. “As two survey aircraft flew over the flat, white, featureless ice sheet, the instrumentation revealed a remarkably rugged terrain below it with deeply etched valleys and very steep mountain peaks.”
The initial AGAP findings – which are based on both the aerogeophysical surveys and on data from a network of seismic sensors deployed as part of the project – while extremely exciting, also raise additional questions about the role of the Gamburtsevs in birthing the East Antarctic Ice Sheet, which extends over more than 14 million square kilometers atop the bedrock of Antarctica, said geophysicist Fausto Ferraccioli, of the British Antarctic Survey (BAS), who led the United Kingdom science team.“We now know that not only are the mountains the size of the European Alps but they also have similar peaks and valleys,” he said. “But this adds even more mystery about how the vast East Antarctic Ice Sheet formed.”
He added that “if the ice sheet grew slowly then we would expect to see the mountains eroded into a plateau shape. But the presence of peaks and valleys could suggest that the ice sheet formed quickly – we just don’t know. Our big challenge now is to dive into the data to get a better understanding of what happened millions of years ago.”
In developing into the origin of the East Antarctic Ice Sheet and the Gamburtsev’s role in it, the science team may also help to address one of the major uncertainties in predicting how much sea level will rise as a result of global climate change. The most recent report of the Intergovernmental Panel on Climate Change (IPCC) said that it is difficult to predict how much the ice caps will contribute to sea level rise because so little is known about the behavior of the ice sheets, including how they form.
The initial data also appears to confirm earlier findings that a vast aquatic system of lakes and rivers exists beneath the ice sheet of Antarctica, a continent that is the size of the United States and Mexico combined.
“The temperatures at our camps hovered around −30 degrees Celsius, but three kilometres beneath us at the bottom of the ice sheet we saw liquid water in the valleys,” said AGAP United States Co-leader Robin Bell, also of Lamont Doherty. “The radar antennas mounted on the wings of the aircraft transmitted energy through the thick ice and let us know that it was much warmer at the base of the ice sheet.”The AGAP discoveries were made through fieldwork that took place in December and January, fittingly near the official conclusion of the International Polar Year (IPY), the largest coordinated international scientific effort in five decades. Ceremonies marking the conclusion of IPY fieldwork will take place in Geneva, Switzerland on 25 February.
Fully in the spirit of IPY, the researchers noted, teams of scientists, engineers, pilots and support staff from Australia, BAS, Canada, China, Germany, Japan and the United States pooled their knowledge, expertise and logistical resources to deploy two survey aircraft, equipped with ice-penetrating radar, gravimeters and magnetic sensors as well as the network of seismometers, an effort that no one nation alone could have mounted.
“This is a fantastic finale to IPY,” said Ferraccioli.
Bell meanwhile, noted that AGAP is “emblematic of what the international science community can accomplish when working together.”
The National Science Foundation (NSF) supported United States researchers from Columbia University, Washington University in St. Louis, Penn State University, the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, the U.S. Geological Survey and the Incorporated Research Institutions in Seismology (IRIS).
In one of the most ambitious, challenging and adventurous ‘deep field’ Antarctic IPY expeditions, AGAP scientists gathered the terabytes of data needed to create images of the enigmatic Gamburtsevs, first discovered by Russian scientists in 1957 during the International Geophysical year, the predecessor to IPY.
While the planes made a series of survey flights, covering a total of 120,000 square kilometers, the seismology team flew to 26 different sites throughout an area larger than the state of Texas using Twin Otter aircraft equipped with skis, to install scientific equipment that will run for the next year on solar power and batteries.
The seismology team, from Washington University, Penn State, IRIS, and the Japan National Institute of Polar Research, also recovered ten seismographs that have been collecting data since last year over the dark Antarctic winter at temperatures as low as −75 degrees Celsius.
“The season was a great success,” said Douglas Wiens, of Washington University. “We recovered the first seismic recordings from this entire part of Antarctica, and operated seismographs over the Antarctic winter at temperatures as low as −75 degrees for the first time. Now, we are poring through the data to find out what is responsible for pushing up mountains in this part of Antarctica.”