Scientists closer to understanding East Antarctic response to climate change

13 December 2013 by Harriet Jarlett

For the first time scientists have begun mapping one of the remotest areas of Antarctica.

The area, called the Recovery Catchment, sits halfway between the South Pole and the Halley VI research station on the Brunt Ice Shelf in northeast Antarctica.

Last year researchers proposed that the Recovery Catchment, which sits above a major glacial basin, could be affected by rising ocean temperatures as early as the end of this century.

It's thought that the dynamics and flow speeds of the ice streams and glaciers underneath the Catchment could be affected by warming ocean waters, which would have a major impact as it's thought to contain enough ice to raise global sea levels by as much as three metres.

While this inaccessible location is currently stable, it has only been assessed in the past by satellite data, so scientists don't know how changes in climate and temperature will affect it.

The ICEGRAV project - a major international collaboration between UK, US, Danish, Norwegian and Argentinian scientists - aims to explore the Recovery Catchment to understand how vulnerable it is to changes in the surrounding ocean and climate.

"Our aim was to explore one of the last frontiers in Antarctica - the Recovery Catchment. We need to understand the underlying topography as this will affect how the area responds to warming oceans," says Dr Fausto Ferraccioli of NERC's British Antarctic Survey (BAS), one of the researchers on the project. "If the bedrock dips inland, away from where the ice sheet meets the sea, it could cause warm water to enter the system and create something called marine ice-sheet instability. If that happens then there's nothing to stop the ice sheet from retreating."

ICEGRAV also hopes to understand whether there are large lakes beneath the area, similar to Lake Ellsworth in West Antarctica. These lakes, known as the Recovery Lakes, could be the largest in Antarctica. Existence of the lakes, first seen in satellite imagery, was brought into question last year when Norwegian researchers on the ground found no evidence for water.

The preliminary findings are being presented this afternoon at the annual American Geophysical Union Fall Meeting by Ferraccioli and colleagues from the Danish National Space Institute and the Norwegian Polar Institute.

This new data has been collected by flying one of NERC's Twin Otter planes 30,000km across the area to measure variations in gravity, ice thickness and magnetism. The survey was based out of Argentina's Belgrano research station, from a remote field location and from the latest state-of-the-art research station in Antarctica, Halley VI, which is operated by BAS.

"Preliminary results from our survey suggest that there's a lot of water there. But subglacial lakes are not the only form of water; it's possible that there are shallower bodies of water that don't form distinct lakes. So now there's the question of how continuous are these features?" Ferraccioli says.

If these lakes exist, they could provide lubrication for the ice sheet, which would make it more prone to change.

The team are also curious about the area's geology as less than one per cent of the rocks in East Antarctica are accessible.

"We know from studies in West Antarctica that the geology beneath the ice sheet plays an important role in controlling ice flow, determining where fast flows occur, the topography and the geothermal temperature. These are all bits and pieces of the puzzle that we need to complete in order to fully comprehend the makeup of East Antarctica and how the ice sheet will react to changes around it," says Ferraccioli.

The nearby Shackleton mountain range is made up of scraps of ocean floor - remnants of an ocean that once separated Africa from East Antarctica - formed 500 million years ago when the continents collided to form the supercontinent Gondwana. Yet just north of these mountains, rocks from the Rodina supercontinent are found that are over 1·1 billion years old.

"Our hypotheses about where mountain belts occur in Antarctica from supercontinent collisions rely on these two very small outcrops in East Antarctica," explains Ferraccioli. "This new survey, including variations in magnetism and gravity, will help us to understand and start discussing how Antarctica fits into the supercontinent puzzle."