A sample of coral

Coral is being analysed to determine changes in climate over time.

Deep-sea corals provide key to climate change

Analysis by the Wealth from Oceans Flagship, CSIRO and US scientists implies that key oceanographic features influencing Australian climate and our coastal environment are changing.

  • 7 March 2006 | Updated 14 October 2011

Scientists are using historical data from deep-sea corals to study and build marine climate scenarios.

CSIRO is recovering corals from depths of 1 000 metres in the Southern Ocean. The deep-sea corals are signalling a previously unknown pattern of temperate and oceanic climate change that has occurred over the past 200 years.

Analysis by scientists from Wealth from Oceans Flagship, CSIRO, Woods Hole Oceanographic Institute, and the California Institute of Technology implies that key oceanographic features influencing Australian climate and the coastal environment are changing.

For example, the East Australian Current is shifting further southward into the Tasman Sea than has previously been recorded. Chemical analysis of ocean corals from the same area and depth indicate a similar, longer-term temperature change deep along the continental shelf.

Scientists believe that this is probably related to shifts in the East Australian Current. These shifts occur due to the surface water warming which causes cooling of the deeper regions of the coast.

Modelling studies and CSIRO observations of the ocean off Tasmania indicate that both the shallow and deep-water changes can be linked to a long-term trend. The long-term trend is related to the cold, rain-bearing winds that buffet southern Australia as they move southward.

By using the new data from corals, trends can be plotted for longer periods than we can observe directly from climate records.

Using new data from deep-sea corals, trends can be plotted for longer periods than climate records allow.

Similar changes in wind fields recorded south of Western Australia have been linked to decreases in the rainfall patterns in the south-west region of Western Australia as well as to the retreat of glaciers in New Zealand.

If the poleward shift in the westerly winds were experienced across temperate Australia, it could have a substantial impact on land use, on the ecology and on distributions of terrestrial and marine species.

In previous studies in Victoria, CSIRO has also observed declines in the levels of lakes. These declines began about the same time that changes occurred in deep-ocean temperatures.

Correlations between temperate Australia and Antarctic indicators suggest that these oceanic changes may also be relevant to Antarctic climate.

Key collaborators

The research is a collaboration of scientists from:

  • Wealth from Oceans Flagship involving CSIRO, the Antarctic Climate and Ecosystems CRC
  • Woods Hole Oceanographic Institute
  • California Institute of Technology.

Funding

Funding for this research is provided by:

  • Fisheries Research and Development Corporation
  • Australian Greenhouse Office
  • Land and Water Research Development Corporation.

Read more about the Wealth from Oceans Flagship.