The largest-ever Australian Antarctic scientific expedition — a five-week study of the Southern Ocean’s role in global processes — ends tomorrow with the return to Hobart of Australia’s ice research ship Aurora Australis.

An international team of 70 scientists from 11 countries travelled thousands of kilometres from Tasmania to Antarctica and back to gather data on how the Southern Ocean influences the world’s climate and the global carbon cycle.

The ship will be welcomed to Hobart by Dr Sharman Stone, Parliamentary Secretary for the Environment and Heritage, who now has responsibility for Australia’s Antarctic Program.

The voyage’s wide-ranging study of changes over time to the ocean’s physical and biological properties involved a traverse from the relatively warm waters near Tasmania to deep into the sea ice zone. Among its key findings:

  • The formation of dense, very cold “Antarctic bottom water” circulating through the world’s oceans is aided by onshore flow of warmer water from the north. Data gathered on this voyage will allow the production rate of Antarctic bottom water to be determined.
  • The voyage confirmed a higher level of biological activity and abundance in the open ocean than previously thought, revealing north-south variations across different oceanographic zones.
  • Scientists found marked differences in production and degradation of methyl bromide, a “natural” ozone-depleting hydrocarbon, and found links between consumption of plant life by microscopic animals and the production of di-methyl sulfide (DMS), a gas that significantly affects the world’s climate.
  • Iron, a key nutrient for Southern Ocean phytoplankton, or single-celled plants, was found to be scarce in both surface waters and sea ice.

The voyage successfully trialled several cutting-edge marine science instruments.