Australia is likely to be between 0.3 and 1.4C warmer by the year 2030 according to CSIRO's latest estimates of climate change for Australia, released today. The temperature increase by 2070 is likely to between 0.6 and 3.8C.
Southern Australia and inland areas are likely to warm more than northern parts of the country.
"CSIRO has based its assessments on the latest international results and on a number of climate models from around the world including the climate models of the CSIRO and the Bureau of Meteorology," said Dr Peter Whetton from the CSIRO Division of Atmospheric Research.
"The scenarios we have released today present the range of climate change plausible during the next 75 years," said Dr Whetton. According to CSIRO's scenarios, much of Australia can expect a decrease in winter rainfall.
In summer the situation is less clear, with different types of climate models yielding different results. Results from newer models that include deep ocean circulation differ from those obtained by older models that include only the shallow surface layers of the ocean.
"Difficulty in assessing likely changes to summer rainfall underlines the critical role the oceans have in determining our climate," said Dr Whetton.
Dr Whetton said that higher temperatures will increase evaporation, which will reduce soil moisture and runoff except where there is a compensating increase in rainfall. Decreases in winter rainfall, and the possibility of further decreases in summer, would have significant implications for water resources, agriculture and biodiversity. The latest scenarios also examine likely changes to tropical cyclones, El Ni–o events, extreme temperatures and extreme rainfall.
CSIRO has taken the international findings of the Intergovernmental Panel on Climate Change (IPCC) into account when developing the scenarios. Allowance has been made for the likely cooling effect of sulfate aerosol pollution.
CSIRO issued its last climate change scenarios in 1992. The latest scenarios reduce the likely range of future temperature increase mainly by reducing the maximum warmings that can be anticipated. The revised Australian assessments reflect changes to global warming estimates released by IPCC earlier this year.
Scenarios of winter rainfall changes are similar to those released four years ago. In summer, however, the latest climate models with deep ocean circulations predict rainfall decreases throughout much of the country. The previous scenarios suggested increases, but were based exclusively on earlier models that incorporated shallow oceans.
Copies of the new, detailed eight-page scenario are available from the CSIRO Division of Atmospheric Research. Broadcast quality video footage is available from the Division of Atmospheric Research.
More information: Dr Peter Whetton 03 9239 4535 (W); 03 9687 7386 (H) Dr Chris Mitchell 03 9239 4550 (W); 03 9499 3508 (H)