By Mike Foley
New scientific findings that overturn traditional assumptions about fuel load management indicate that climate change is reducing the effectiveness of hazard reduction burning.
During the 2019-20 black summer fires Prime Minister Scott Morrison raised concerns over the scale of hazard reduction, which is managed by state governments, and called for a national approach that was aimed at shaming states into action.
Federal Emergency Management Minister David Littleproud had earlier launched an inquiry in 2019 into states’ rates of hazard reduction.
But NSW and Victoria moved away from annual targets for hazard reduction burning in recent years, following expert warnings the strategy incentivised agencies to seek easy fuel load reductions in remote locations that did little to reduce risks to lives and property.
Griffith University Professor Brendan Mackey said the drying, heating climate under global warming made hazard reduction burning increasingly less effective. Black summer fires claimed 33 lives, destroyed 3000 homes and left thousands homeless.
He said hazard reduction burns within one kilometre of houses and towns must be carried out every few years to slow the path of fires and reduce their potential to claim lives and property.
“There has been an irreversible change in fire weather conditions since the 1970s - put simply, the game has changed,” Professor Mackey said. “Targeted burning within one kilometre of houses and towns can help to protect them from bushfire, but it must be done every three years.”
Professor Mackey contributed to the Bushfire Recovery Project, a joint initiative between Griffith University and the Australian National University, to inform the public about the latest peer-reviewed scientific advice.
The study’s finding is contrary to broader public opinions. The bushfire royal commission into the black summer blazes received 1300 submissions and many came from residents in fire prone regions who were concerned about rates of hazard reduction.
It also found climate change is lengthening the fire season and increasing the risk of extreme fires by reducing winter rainfall in southern Australia, further drying bushfire fuel loads and bringing hotter springs.
Australia experiences 10 times more extreme fire danger days each year than in the 1960s, with an average of more than 140 a year in the past decade.
ANU bushfire and landscape expert Professor David Lindenmayer said global warming had “hugely” reduced the effectiveness of fuel reduction burning, particularly in extreme fire danger weather.
“The peer-reviewed evidence is that burning forest miles from houses doesn’t protect those houses,” Professor Lindemayer said.
The royal commission found while lives and property were largely lost on extreme fire danger days but controlled burning to reduce fuel loads “may have no appreciable effect under extreme conditions”.
“The weight of research into the effects of fuel reduction on the propagation of extreme bushfires indicates that as conditions deteriorate, fuel reduction is of diminishing effectiveness,” the inquiry’s final report found.