Scientists come home with new climate insights

Five people working on sea ice to set up equipment.
Setting up a sea ice station. (Photo: ACE CRC)

17 October 2007

An international team of scientists from ten nations returns today from a six-week voyage studying Antarctic sea ice, bringing with them fresh insights into whether climate change is affecting the ice and ecosystems of the Southern Ocean.

An extensive science program led jointly by the Antarctic Climate & Ecosystems Cooperative Research Centre (ACE CRC) and the Australian Antarctic Division, has gathered valuable information that will help develop more accurate global climate models and will also help us understand how polar ecosystems might react to future climate change.

Researchers have generated many new findings using a suite of cutting-edge technologies, with airborne laser altimetry and radar and an under-ice remotely operated vehicle the highlights.

Voyage Leader Dr Tony Worby said that for the first time ever in Antarctica, helicopter flights covered thousands of kilometres tracking over the sea ice, gathering large-scale information about ice and snow conditions in the region.

"Two helicopters, equipped with laser and radar altimeters, were used to measure the height of the snow and ice surfaces above sea level.

"The helicopter data were complemented by information gathered from ice coring and other work directly on the ice. The combined information will help validate satellite altimetry data, which will eventually be used to monitor changes in sea ice thickness around Antarctica," Dr Worby said.

Sea ice researchers also made the first measurements of the fluid permeability – the ability of fluid to flow through channels in the ice – of the seasonal Antarctic sea ice pack. With permeability affecting a range of processes in global climate, polar biology and oceanography, these initial data will have important implications.

Biologists combined classical ice coring techniques with the remotely operated vehicle (ROV) to study the underside of the sea ice, to map the distribution of ice algae – microscopic plants that live in and on the underside of the ice.

Dr So Kawaguchi, marine ecologist with the Australian Antarctic Division, said that the ROV observations showed high concentrations of Antarctic krill living at the underside of the sea ice as well as in cracks between ice floes.

"Using trawls and underwater cameras, the biology team mapped the distribution and the condition of the krill.

"Krill found in and around the ice were in better condition than those found in areas of open water.

"The krill are feeding on the ice algae and, in turn, serve as a food source for penguins, seals and whales.

"An unusual observation was the co-occurrence of three krill species that generally live in very different oceanographic regions," Dr Kawaguchi said.

Other scientists worked on ice algae physiology and sea ice biogeochemistry to better understand processes in the Antarctic sea ice zone during the transition from winter to summer.

Oceanographers studied the water mass properties and currents beneath the sea ice and found that, contrary to what was expected, the patterns of sea ice drift appear to be affected more by ocean currents than by wind.

The Sea Ice Physics and Ecosystems Experiment (SIPEX) is an International Polar Year project. Throughout the voyage the team posted daily reports on the voyage web site and blog.