By Pauline Askin
SYDNEY (Reuters) - Scientists have produced the first three dimensional map of the surface beneath Antarctic sea ice, helping them better understand the impact of climate change on Antarctica.
The team of scientists from eight countries have used a robot submarine to chart a frozen and inverted world of mountains and valleys, allowing accurate measurements of the crucial thickness of Antarctic sea ice.
By combining the data with airborne measures of surface ice and snow, scientists can now accurately measure changes in ice thickness and better understand the affects of global warming.
"The ice thickness is regarded amongst climate scientists as the holy grail of determining changes in the system," Antarctic marine glaciologist Jan Lieser told Reuters.
"If we can determine the change in the thickness of the sea ice we can estimate the rate of change that is due to global warming."
Scientists have ice thickness data for the Arctic region dating back to the 1950s, allowing for analysis of changes in the Arctic Ocean, but similar data has been unavailable for the ice around the frozen Southern continent.
Lieser, who is aboard an Australian icebreaker in Antarctic waters, is part of the Sea Ice Physics and Ecosystem Experiment project, involving scientists from Australia, Belgium, Canada, France, Germany, Japan, New Zealand and the United States.
They are using a free-swimming robot submarine, which moves about 20 meters (65 feet) below the ice and travels in a grid pattern, using multi-beam sonar to measure the underside of the ice.
Lieser said changes in sea ice thickness affects the formation of cold, salty Antarctic bottom water that drives global ocean currents and is crucial for sea life, from phytoplankton and krill to whales.
"We can actually get a full 3D image of what we are measuring. It's never been done before and that's really exciting," Lieser added.
The results will help set a baseline to establish how climate change affects Antarctic sea ice. Scientists will also be able to examine how changes to sea ice affect the ecosystem.
Similar tests in 2007 used only airborne equipment and produced only two dimensional maps, which are less accurate.
(Reporting by Pauline Askin, editing by Elaine Lies)