Extreme drought conditions and fire weather – not logging – were the key drivers behind the record-breaking Black Summer bushfires in New South Wales, say scientists.
Their findings slap down a theory touted by climate change deniers that forest mismanagement, rather than climate change, was largely to blame for the devastation.
As part of their peer-reviewed research, released on Tuesday, scientists across Australia studied three regions in NSW that comprised about a third of the total area burnt in the summer of 2019-20.
They found logging and damage from previous bushfires in natural Eucalyptus forests had a very low effect on canopy destruction.
Instead, landscape features like mountain ridges – coupled with hot and windy weather – were largely responsible for the flames spreading out of control.
Generally, a fire will run more quickly uphill than downhill or on flat terrain, making it harder for firefighters to catch it in time.
Add to that ferocious winds, and it’s a deadly combination.
The study, published in the Nature Ecology & Evolution journal, also found 70 per cent of the NSW timber plantations suffered serious canopy damage, demonstrating this intensive type of wood production is extremely vulnerable to bushfire.
Some critics, however, said the research paper was misleading.
Philip Zylstra, an adjunct associate professor at Curtin University who was not an author of the paper, said analysing how much of the severely burnt areas had been recently logged was beside the point, because the argument is logging makes more crown fires that are impossible to control and have huge effects on the final size of the fire.
Earlier research, including by some of the authors of the current paper, had shown that logging increases the likelihood of crown fires, he said.
“They did actually show that… logged forests were about as likely to scorch on mild days as undisturbed forests were on very high fire danger days,” he said.
The blame game
As the Black Summer bushfires raged during 2019-20, so too did a fiery debate between Australian news outlets and politicians over the role of climate change.
More than half (54 per cent) of discussion blaming “greenies” for getting in the way of hazard reduction efforts appeared in News Corp publications, a Monash University media report found.
And although News Corp made up 25 per cent of overall accurate and in-depth coverage of climate change, the news giant also represented 59 per cent of all denialist discussion of climate change.
Conservative politicians like Nationals MP Barnacy Joyce added fuel to the flames by saying a lack of hazard reduction burns, not climate change, was the main culprit for Australia’s bushfire crisis.
But the author’s findings contradict this theory.
“There is no scientific consensus about the possible effects of logging on fire risk, despite many media claims to the contrary,” wrote Professor David Bowman, a fire science expert at the University of Tasmania and co-author of the study.
“The relationship between logging and fire is contingent on fire weather, landscape settings and environment.”
Professor Bowman said the shocking scale and severity of the bushfires were best explained by “extreme drought and anomalous fire weather conditions”.
“Our research is deeply concerning because it signals that there are no quick fixes to the ongoing fire crisis that is afflicting Australia and other flammable landscapes globally,” he said.
“This crisis is being driven by relentless climate change, which has the terrifying potential to switch forests from critical stores of carbon to volatile carbon sources.”
The authors said that in the future, fuel loads like bark and debris were likely to become less important than climate drivers in determining fire extent and severity.
This makes it increasingly difficult – if not impossible – to lower fuel loads in a way that will limit the severity of bushfires, they said.