Unraveling the changing patterns of Australian rainfall

Figure 1. The tropical waters around Indonesia are an important source region for Australia’s rainfall.

The warm tropical waters of the eastern Indian Ocean are an important source of rainfall for Australia. When the temperature of the water in this area is warmer than usual Australia receives more rain, while cooler ocean temperatures cause widespread drought. Understanding the cycles of Australian droughts and floods, and how these patterns might be affect by climate change, requires a long-term perspective on what causes ocean temperature and atmospheric convection in the tropics to vary. This type of information can be reconstructed by using the detailed climate records preserved in the skeletons of corals.

This research project will involve micro sampling coral cores from the eastern Indian ocean and performing stable isotope and trace element analysis to assess the variability of SST and rainfall in the past. This will provide a new understanding of how sensitive Australian rainfall patterns are to changes in ocean temperature in the tropical eastern Indian Ocean.

Figure 2. Coral skeletons, like tree rings, have annual growth bands that can be analysed in detail to reconstruct past changes in ocean temperature and tropical rainfall.