Scientist: Bush Fires Part of an Ancient Cycle
Copyright 2001 Reuters
December 28, 2001
By Michael Byrnes
SYDNEY (Reuters) - The bush fires which devastated areas around Australia's largest city over Christmas are part of a naturally recurring cycle, although this maybe becoming more frequent, a leading Australian fire scientist said.
More than 100 fires have sent hundreds fleeing, destroyed homes, blanketed Sydney in thick smoke and dumped ash and charred leaves in backyards. They have erupted just seven years after 1994 bush fires which swept through the city's suburbs and while police believe nearly half of them could have been deliberately started, in the natural cycle it still seems too soon.
``Conditions like this usually occur somewhere in Australia about every three years. But in any particular location, maybe once every 10 years or so,'' Phil Cheney, senior principal research scientist with the Commonwealth Scientific and Industrial Research Organization (CSIRO), told Reuters.
``It's at the high end of the range,'' he said of the outbreak of two major fires around Sydney with only a seven year gap.
Research back to 1850 showed bad fire seasons occurred in particular parts of Australia every 13 years or so.
Fires of the intensity of the Ash Wednesday fires, which swept through South Australia and Victoria states in 1983 to cause 76 deaths and the loss of many thousands of homes, would occur only on a 50 year cycle.
``We've probably recorded that sort of condition (intensity) maybe four or five times in 200 years,'' Cheney said.
CYCLE OF FIRE
Debris builds in native Australian bushland, where eucalyptus and banksias have adapted to fires, waiting for them to crack their seed pods, stimulating regeneration. With ideal bush fire conditions of six months drought and a 13-year gap between major fires, a lightning strike is enough to explode native Australian trees, full of their combustible oils.
Authorities believe lightning set off the first of the fires now ringing Sydney. This, New South Wales Rural Fire Commissioner Phil Koperberg believes, then sparked thrill-seeking arsonists into lighting fires which were whipped by 60-km (36-mph) winds.
The fury of the Sydney fires was so great on Christmas day that they jumped Warragamba Dam, Sydney's major water supply, as if it wasn't there, Koperberg said.
Waterbombing is virtually useless, fire experts say. Only wind shifts or rain can counter fires of this intensity.
TO BURN OR NOT TO BURN?
As Sydney waits, with no rain forecast for days, the fires are reigniting debates over whether authorities should have been fighting fire with fire through controlled burning.
``It's futile to be suggesting that extra hectares of fuel reduction could have had any significant reduction at all on the type of fires we've been experiencing,'' NSW Emergency Services Minister Bob Debus told a press conference on Thursday.
The main body of the fire on Christmas Day shot flames more than five kilometers ahead of it in some areas, he said. Others believe environmental trendies and a widespread lack of understanding of the use of controlled burning is helping to increase the frequency of major bush fires.
``People don't use fire as much as they used to. Thirty or forty years ago fire was used commonly,'' Cheney said.
Regulations have tightened restrictions on fires. Graziers burned bushland more before intensive agriculture arrived.
``With management and careful planning I believe much more fire can be applied by land management agencies in an ecologically sensible way,'' he told Reuters.
``A lot of the population is urban-based and don't understand the role of fire in the natural environment. And there is a natural aversion against fire, longstanding in our heritage, being largely European based.''
This was quite different from indigenous Australians, who used fire to manage the land.
``I believe that in many areas National Parks can use prescribed fire as part of their park management,'' Cheney said.
Part of the solution might be in everyone's back yard.
``It really has to be managed at the interface. People that live within 200 meters of the bush (need)...to create some sort of a break between urban areas and the bush.''
Scientists admit that forces behind the big fires are imperfectly known. Records are not extensive enough. Reactions between bush fires, ocean currents and El Nino weather events, which send dry weather over eastern Australia every four or so years from changing Pacific Ocean sea temperatures, are not fully clear.
But mainstream scientists see a buildup of greenhouse gases and global warming increasing the frequency of El Ninos. Could they be helping to unleashing more frequent bush fires too?