French scientists probe deep into Antarctica for clues on climate change
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French scientists have reported on an international mission to one of the most desolate regions of Antarctica, where they spent more than a month gathering data to help predict sea level changes and understand the Earth’s climate history.
The mission, called the East Antarctic International Ice Sheet Traverse (EAIIST), involved 12 scientists, three logisticians and a doctor spending more than 40 days crossing one of the most arid and remote parts of the Antarctic interior.
“They travelled 1,370 kilometres from Concordia into unknown territory,” said Jérôme Chappellaz, director of the French Polar Institute, which oversees France’s research on Antarctica, at a presentation of the mission at French National Centre for Scientific Research (CNRS) campus in Paris. “It’s the first time scientists have ever gone there.”
Setting out from Franco-Italian research station Concordia 1,100 kilometres from the coast, the mission involved pulling along nearly 250 tonnes of equipment, mobile laboratories and life support units where living quarters are nearly as reduced as those on a space station, at an average of 10 kilometres per hour.
“It’s very flat, very white, very bright and quite cold,” said Pete Akers, an American postdoctoral researcher with the Institute for Environmental Geophysics in Grenoble, via satellite link from the Concordia base. “On the plateau, you’re so high and so far from the ocean, it’s hard for clouds, moisture and storms to get here.”
Up to minus 45 degrees Celsius
The extreme dryness and isolation of the plateau mean it holds some of the purest and oldest ice and snow on the continent, which scientists sought to collect to better understand how the continent’s climate behaved over past millennia.
Working at 3,200-metre altitudes and in temperatures ranging from -25 to -45 degrees Celsius, the team installed weather stations and gathered hundreds of snow samples and six tonnes of ice core, long rods of ice drilled from up to 200 metres into the ground.
“We’re trying to reconstruct snow accumulation rates for Antarctica based on nitrogen in the snow,” Akers said. “This is important when we’re looking at long ice cores and the history of Antarctica, so we can figure out how the weather’s changed in the past.”
The ice core samples, which total 900 metres of rods, will be taken to mainland France and studied over the coming year. Data will be cross-checked with that from Concordia to ensure scientists are interpreting the samples properly.
Glazed surfaces and mega-dunes
Scientists are also hoping to better understand a landscape they believe has remained virtually unchanged since the last ice age and that comprises features called glazed surfaces and “mega-dunes”.
Glazed surfaces are icy surfaces with virtually no snow accumulation that cover up to 1.5 million square kilometres of Antarctica, or as much as 15 percent of the whole continent.
Mega-dunes, surface undulations created by sustained winds spread over so large an area they are only visible on satellite images, cover another 500,000 square kilometres.
Understanding their age and formation is essential to interpreting the data contained in the ice cores as well as understanding precipitation on the continent, which has a curious relation to monitoring the rise in sea levels.
Compensating for rising sea levels
A recent report of the United Nations Intergovernmental Panel on Climate Change that identifies Antarctica as an unknown factor when it comes to predicting how sea levels will rise in through the century.
“What scares scientists who specialise in the area the most is the instability of the Antarctic continent,” said Joël Savarino, head of the EAIIST scientific mission and CNRS research director.
Compared with Greenland, where melting is increasing but in a predictable and essentially linear manner, Savarino said Antarctica comes with “the possibility of a catastrophic ice breakup”.
But scientists suspect a warming climate may also boost precipitation in the interior of Antarctica, boosting precipitation and thereby storing mass and acting as a kind of compensation to the sea level rise.
“What we expect in a warmer world is that more water from the ocean is transferred to the interior of the Antarctic continent to produce snowfall and accumulation,” Jérôme Chappellaz explained.
“We are sure it will not be strong enough to compensate the amount of ice that is lost every year, but it’s a partial compensation. The question is how much?”
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