Sydney Morning Herald

September 27, 2007

New species of fire monster heading our way

Wendy Frew Environment Reporter

BUSHFIRES that burn so hot they cannot be controlled are likely to occur much more frequently in Sydney in the years to come, razing bushland, leaving property more susceptible to flooding and threatening water supplies, new research indicates.

The level of very hot weather being experienced now, in which fierce fires can break out, has already surpassed what had been projected for 2050, the report on bushfire weather in south-east Australia by the Australian Bureau of Meteorology and the CSIRO says.

"Whether it is caused by climate change or not, the pattern of the past few years gives us a model for the future," said Dr Chris Lucas of the bureau's Bushfire Co-operative Research Centre. "How are we going to manage this level of fire risk? What are we going to do to manage these fires?"

Of most concern to fire fighters are days classified as having very high or extreme fire danger. The report projected that in NSW those days would increase in four scenarios examined.

For example, at present inner Sydney experiences one day a year of extreme fire danger. If the rate of global warming is low (a rise of 0.4 degrees above 1990 temperatures), the number of extreme fire days increases by between 11 and 21 per cent by 2020 and from 13 to 34 per cent by 2050 (with a rise of 0.7 degrees).

If the rate of global warming is high the number of extreme days rises by between 26 per cent and 50 per cent by 2020 and by as much as 200 per cent by 2050 when temperatures are expected to have risen by 2.9 degrees.

Richmond, on Sydney's western outskirts, does not currently experience what is defined as a catastrophic fire weather day but with high levels of warming they may occur every four years by 2050. The same is true for inner Sydney.

The more extreme the hot weather, the more damaging any fire that breaks out, Dr Lucas said. In the case of catastrophic hot weather, fires become uncontrollable, with only a change in the weather likely to help bring them under control. "Anything above the 'extreme' category is uncontrollable," Dr Lucas said. "Even fires that break out on very high-danger days would need a lot of work to put out."

He said with fires burning hotter and longer, they not only posed a threat to bushland and property but degraded the land, eroded soil and changed water run-off patterns.

"Some research has found that after a big fire you are more susceptible to floods because there is nothing to hold the water back."

posted to ClimateConcern