The ocean influences the Earth’s climate by storing and transporting vast amounts of heat, moisture and carbon dioxide. Heat absorbed by the ocean in one location may be carried thousands of kilometres before being released to the atmosphere. This release of heat in turn drives motions in the atmosphere that determine the large-scale, slowly evolving temperature and rainfall patterns that make up our climate.
The Southern Ocean is a crucial cog in this global heat engine, in part because of its unique geography — it occupies the only band of latitudes on Earth where ocean waters circle the globe. This has profound implications for the global ocean circulation and the Earth’s climate system.
To read more about the effect of the Southern Ocean on the world’s oceans and global climate read the Australian Antarctic Magazine story The Southern Ocean’s Global Reach and Chapter 4 of the 2008 report Australia’s contribution to Antarctic climate science.
As well as studying the physical processes of the Southern Ocean, the Australian Antarctic Division conducts various chemical and biological ocean research. You can learn more about our ocean research in the Science pages of our website. We also conduct ocean research through the Antarctic Climate and Ecosystems Cooperative Research Centre. The information below provides a snapshot of some of our work.
Ocean acidification poses the biggest threat to our ocean ecosystems. Research has shown that about half of all the carbon dioxide (CO2) released by human activities is now found in the world’s oceans and that about a third of this has been taken up in the Southern Ocean. As CO2 continues to dissolve in the ocean it increases ocean acidity, making it harder for some marine organisms to form shells. Among the organisms affected are beautiful and unusual marine snails known as ‘pteropods’, as well as some species of algae and corals. Read more about ocean acidification and its impact on marine organisms in our Fact Files.
Did you know that whale poo may act as a fertiliser in the world’s oceans? Australian Antarctic Division scientist, Dr Steve Nicol, explains that large whales in the Southern Ocean consume large quantities of krill, but because they produce blubber, rather than muscle, they have no need for the iron in their diet. Consequently, this essential element passes straight through their digestive tracts and exits their bodies in a plume of faecal material that acts like liquid manure.
A number of studies have shown that the growth of microscopic algae in the Southern Ocean is limited by the iron concentration in the water. Iron enters the ocean either through wind-blown dust from the Antarctic continent or through the upwelling of water from the ocean depths. The deep water is richer in nutrients because particulate matter, including dead algae and detritus, sinks out of the sunlit layer to the ocean’s interior, where microbial processes break it down into its constituent chemicals. Any process that keeps the nutrients in circulation in the surface layer, rather than sinking, should ensure that algal growth is sustained. This is where the notion of whales as fertilisers of the ocean comes in. To learn more about this interesting hypothesis read Whale poo fertilises oceans.
Much of our biological research in the Southern Ocean is conducted through our Southern Ocean Ecosystems: Environmental Change and Conservation science program. On a voyage to Antarctica in 2009–10, scientists spent many weeks studying the benthic (sea floor) environment and the creatures that live there. In the deepest parts of our oceans, these animals are often adapted for life in extreme environments, where there’s no light, intense cold and huge amounts of pressure from hundreds if not thousands of metres of water above. Getting a glimpse of this weird undersea world requires some special equipment, like cameras mounted in special pressure-resistant housings and strong nets that are dragged along the sea floor to collect wildlife samples. Find out more about these creatures of the deep and read about the voyage in Southern Ocean marine life in focus.
One of our longest running biological studies is measuring changes in plankton in the Southern Ocean. A Continuous Plankton Recorder (Australian Antarctic Magazine 13: 12–13, 2007) is towed behind ships, where it captures tiny marine plants and animals that make up the plankton. After 20 years of research, scientists are seeing changes in the abundance and types of plankton species captured. Read more in Twenty year study finds major changes in Southern Ocean plankton.