Predicted changes to Australia's climate system

Scientists have used historical climate information and made assumptions about future emissions and their likely chemical reactions in the atmosphere to provide a global climate model, or an idea, of what the climate will be like by the year 2030 if current emissions across the world are not reduced.

Temperature

Average temperatures. In relation to 1990 temperatures, it is estimated that average temperatures may rise by 0.7-0.9°C in coastal areas and 1.0-1.2°C in inland areas of Australia by 2030.
Extreme temperatures. It is projected that the number of hot days and warm nights will increase, while the number of frost days will decrease moderately.

The table below shows that by 2030, the average number of days above 35°C at most sites is predicted to increase by 5-20% under a low emissions future, and by 50-100% with higher emissions. By 2070 the number of days exceeding 35°C, and spells above 35°C, increase dramatically.

Table 1. Average number of days per year above 35°C at 12 NSW sites for present conditions (1964-2003), and temperature range¹ predictions for 2030 and 2070. (A 'hot spell' is three consecutive days above 35ºC.)

Site	Days exceeding 35°C			Spells above 35°C
	Present	2030	2070	Present	2030	2070
Wilcannia	59	62-83	70-136	13	14-20	16-37
Cobar	41	44-65	51-128	9	10-15	11-35
Walgett	56	61-87	71-153	12	14-21	17-44
Gunnedah	19	22-40	29-103	3	4-8	6-26
Yamba	1	1-2	1-7	0	0-0	0-0
Bathurst	4	4-11	6-43	0	1-2	1-9
Sydney	3	4-6	4-18	0	0-0	0-1
Moruya	2	2-3	2-6	0	0-0	0-0
Canberra	5	6-13	8-42	1	1-2	1-9
Wagga	20	21-34	25-78	3	4-7	4-20
Wyalong	26	27-42	32-93	5	5-9	6-23
Deniliquin*	24	25-37	28-75	4	4-7	4-17

* At Deniliquin, present conditions refer to 1963-2002.

Source: Hennessy et al 2004.²

Rainfall

Models predict a reduction in rainfall of between 2% and 5%, but natural rainfall differences which occur over the course of decades may mask any reductions in rainfall due to climate change.

Predicted changes in rainfall for the year 2030.
Source: CSIRO,* reproduced with permission, from http://www.climatechangeinaustralia.
gov.au/nswactrain4.php

*Disclaimer: CSIRO does not guarantee that the material or information it has provided is complete or accurate or without flaw of any kind, or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise directly or indirectly from you relying on any information or material it has provided (in part or in whole). Any reliance on the information or material CSIRO has provided is made at the reader's own risk.

The figure at right shows the predicted changes in rainfall for the year 2030. The shading indicates a percentage change from averaged climate data collected during the period 1980-1999. These figures represent the 50th percentile, or the most reliable result based on the estimates of a future with a medium level of greenhouse gas emissions (A1B scenario under IPCC Special Report on Emission Scenarios).

It is predicted that during winter, rainfall will be reduced by between 2% and 5% across NSW, as shown by the yellow and orange colours.

Return to Observations in Australia and NSW.

¹Ranges are given because of the uncertainty in the climate prediction models. There are uncertainties in the predictions because future greenhouse gas emissions are hard to predict. The range therefore represents a number of models based on if action is taken to reduce greenhouse gas emissions, and a future without any specific actions to reduce greenhouse gas emissions.

²K Hennessy, K McInnes, D Abbs, R Jones, J Bathols, R Suppiah, J Ricketts, T Rafter, D Collins & D Jones, 'Climate change in New South Wales, Part 2: Projected changes in extremes', Consultancy report to the NSW Greenhouse Office, CSIRO, 2004.