As Sydney and Brisbane clean up from severe storms and the planet heads towards its hottest year on record, the CSIRO is warning the cost to replace buildings exposed to extreme weather could cost Australia more than $1 trillion.

The ABC has obtained advice from the nation's premier science agency warning climate change and poor planning were leaving the nation increasingly exposed to natural disasters.

The CSIRO draft discussion paper said the cost of replacing homes and other buildings exposed to bushfires, inland flooding and coastal inundation could almost double by 2100 to $1.38 trillion.

"All evidence suggests that the current trend of increasing disaster costs will continue into the future with a direct impact on Commonwealth expenditure," the CSIRO said.

"Climate change is likely to increase this trend in the longer term for many hazards."

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Climate scientist Professor Andy Pitman from the University of New South Wales said for now much of the problem was coming from poor planning decisions.

"People are building increasingly beautiful houses close to bush or close to the oceans, and it shouldn't be a surprise if those are vulnerable to climate change," he said.

It mirrored analysis done by Risk Frontiers, a research centre sponsored by the insurance industry to understand natural hazard risks.

"If you look at the 2009 Black Saturday fires - in two of the towns most severely damaged - 25 per cent of destroyed buildings were located physically within the bushland boundary," chief research officer Dr Ryan Crompton said.

"Sixty per cent of the destroyed buildings were within 10 metres of [the bushland boundary], so clearly there was high risk in those areas."

More cyclones and greater intensity of rain tipped

Risk Frontiers said analyses of long-term trends in insurance or economic disaster loss histories had not so far been attributed to climate change.

Professor Pitman said if the climate continued to change, so too would the vulnerability of some communities.

"We know it's going to be hotter, we know there'll be intensification of heavy rainfall that will tend to exacerbate flood risk," Professor Pitman said.

"There are hints of changes of distribution of cyclones and there's evidence of changes in the frequency of cyclones and we suspect on the intensity of cyclones.

"We might start to see cyclones in areas we haven't seen previously and that builds phenomenal levels of vulnerability into regions that have been developed without worrying about cyclone risk."

Townsville's James Cook University Cyclone Testing Centre director David Henderson is researching how to cheaply make older homes more resilient to disasters.

"We're actually saving a lot of money by mitigating for this damage now as opposed to waiting and fixing it after," he said.

According to Dr Henderson, it was up to seven times more expensive to repair a property than to protect it in the first place.

Documents showed the CSIRO would continue to investigate options for the government to budget for climate risk.

They included considering:

allowances for specific potential liabilities (for example for the National Disaster Relief and Recovery Arrangements)

allowances for specific potential liabilities (for example for the National Disaster Relief and Recovery Arrangements) a statement of climate risks in the budget papers.

a statement of climate risks in the budget papers. a discussion of longer-term implications of climate risks for the Commonwealth's fiscal position in the Intergenerational Report.

The warning comes as the Climate Action Tracker, produced by an independent group of scientists, said temperatures were set to rise by about three degrees Celsius above pre-industrial times by 2100.

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