11.7.1 Key Processes

Key climate processes affecting the Australian region include the Australian monsoon (the SH counterpart of the Asian monsoon), the Southeast trade wind circulation, the subtropical high-pressure belt and the mid-latitude westerly wind circulation with its embedded disturbances. The latter two systems also predominate over New Zealand. Climatic variability in Australia and New Zealand is also strongly affected by the ENSO system (McBride and Nicholls, 1983; Mullan, 1995) modulated by the Inter-decadal Pacific Oscillation (IPO; Power et al., 1999; Salinger et al., 2001). Tropical cyclones occur in the region, and are a major source of extreme rainfall and wind events in northern coastal Australia, and, more rarely, on the North Island of New Zealand (Sinclair, 2002). Rainfall patterns in New Zealand are also strongly influenced by the interaction of the predominantly westerly circulation with its very mountainous topography.

Apart from the general increase in temperature that the region will share with most other parts of the globe, details of anthropogenic climate change in the Australia-New Zealand region will depend on the response of the Australian monsoon, tropical cyclones, the strength and latitude of the mid-latitude westerlies, and ENSO.