Expert predicts more mega-bushfires

Australians should brace themselves for more mega-bushfires as climate change takes hold, a leading scientist warns.

Professor Will Steffen from the Australian National University (ANU) says climate change is expected to cause hotter, drier weather in areas like Victoria.

That means fires are more likely to spread - and the fuel could be tinder-like when they do.

"Events like this, severe heatwaves and severe fires, become more likely with an underlying change in climate," Prof Steffen, who is director of ANU's Climate Change Institute, told AAP.

"People better prepare for the fact that the risk is increasing ... (for) more frequent extreme events that are related to temperature, like heatwaves, like bushfires."

He noted Victoria had extremely high temperatures during last weekend's horrific bushfires, and that heatwaves were more likely due to climate change.

Prof Steffen could not say if the Victorian bushfires were caused by climate change.

It was difficult to blame any single weather event on greenhouse gas emissions, he said.

But he said climate change was heating up Australia.

"Our climate is getting warmer, as it is in the rest of the world, and I think there's no doubt about that," Prof Steffen, an expert in terrestrial ecosystems and climate change, said.

There was a strong scientific consensus that the bulk of warming since 1950 had been caused by increased greenhouse gases in the atmosphere, he said.

Prof Steffen said climate change could increase the frequency of mega-bushfires from once every 100-200 years, to once every 20-30 years.

Victorian Premier John Brumby has linked the recent fires to global warming.

"There's clear evidence now that the climate is becoming more extreme," he said on Monday.

Australian Greens leader Bob Brown said extreme bushfires would become more frequent if the world failed to act on climate change.

"Global warming is predicted to make this sort of event happen 25 per cent, 50 per cent more," Senator Brown said on Sunday.

Greenpeace climate campaigner Trish Harrup pointed to the Victorian bushfires as she called for Australia to beef up its promise to cut greenhouse gas emissions by five to 15 per cent by 2020.

"The scale of this catastrophe, coupled with severe floods in Queensland, should be a clarion call to politicians for the need to begin treating climate change as a national emergency," Ms Harrup said.