Chapter 4 Climate Impacts and Responses

Introduction

Climate variability and trends impact on Australia’s economy, environment and society. Australian research organisations are conducting many research projects to understand the magnitude of climate change (including natural variability and human induced climate change) and the physical drivers that underpin our ability to forecast and manage its impacts.

Australia’s average temperature varies by up to 1 degree Celsius from year to year, and has experienced a warming trend of about 0.8°C since 1910, most of this since 1950. Averaged over Australia, maximum temperatures have risen 0.56°C since 1910 and minimum temperatures have risen 0.96°C, with the largest warming since about 1950. According to CSIRO projections released in mid-2001, which use as their reference point the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), annual average temperatures over most of the continent could be 0.4 to 2°C greater than 1990 by 2030. By 2070, average temperatures are projected to increase by 1 to 6°C. Warmer conditions will produce more extremely hot days and fewer cold days and frosts. Greatest warming is to be expected in spring and winter will warm the least.

Australia’s current rainfall averaged over the whole continent is about 450mm a year, varying between 300-800mm in any year (with the variability much larger in specific regions). Averaged over Australia, annual total rainfall has increased slightly since 1910 and the intensity of heavy rainfall has also risen. According to the CSIRO projections, rainfall decreases are projected for the southwest of Western Australia and for parts of the southeast of the continent and Queensland. Most other locations have an even chance of wetter or drier conditions. Decreases are projected to be most pronounced in winter and spring. Some inland and eastern coastal areas are projected to become wetter in summer, and some inland areas to become wetter in autumn. These projections include the effect of simulated changes in El Niño and La Niña events.