Sea ice plays an essential role in regulating global climate as well as supporting the Southern Ocean ecosystem. Sea ice could be expected to respond to global warming and was therefore like a canary in a coal mine, said Australian glaciologist Tas van Ommen.
The ice is also highly reflective of sunlight. Less ice would directly cause heating of the Southern Ocean, he said. Loss of sea ice could also slow deep, cold briny currents that drive the circulation of the oceans, he said.
The six-week international expedition aboard the Antarctic research ship Aurora Australis, now in the Southern Ocean, is using two helicopters equipped with laser altimetry equipment to measure sea ice thickness. These will be tested against satellite-based measurements taken as part of a separate U.S. National Aeronautics and Space Administration (NASA) IceSat science project.
Prior to this experiment, very few measurements had been made and any changes might have gone unnoticed, said expedition leader Dr Tony Worby of Australia's Antarctic Climate and Ecosystems Cooperative Research Centre.
"The laser work we are doing is going particularly well. We are collecting excellent data which we expect will considerably improve our knowledge of sea ice in this region of Antarctica," Worby said.
The ultimate aim of the helicopter altimetry, combined with the surface measurements, is to help validate and improve measurements from satellites. These can then be used to estimate Antarctic sea ice thickness over large areas, the Australian Antarctic Division said. While laser altimetry has been used in the Arctic, it is the first time it has been tested in the Antarctic.