The CSIRO says Australian temperatures could rise by as much as 5ºC over the next 63 years - if greenhouse gas emissions are not curtailed.

Its Climate Change in Australia report, released last week, found that a worst-case scenario of high emissions will create more extreme weather events, such as droughts and cyclones.

Even under the best-case emissions scenario, greenhouse gases already in the atmosphere are likely to cause average temperatures to rise about 1ºC by 2030. Beyond that, the extent of global warming will depend on the amount of greenhouse gases released into the atmosphere in the immediate future.

A low-emissions outlook would have temperatures rising 1-2.5ºC by 2070. High emissions would cause warming in Australia of 2.2-5ºC.

Rainfall is certain to decrease in southern Australia. With low emissions, CSIRO predicts annual rainfall will decline 7.5%, and a high-emissions outlook will mean a 10% decline.

The report represents an update of projections from 2001. The CSIRO says the new projections have a narrower band of error, indicating improved consistency between models.