Can we really fight fire with fire? Why pre-burning is no magic bullet

Like clockwork after every wildfire, such as those in the Grampians and now in Los Angeles, politicians and other commentators invariably call for more prescribed burning. They say low intensity fires deliberately lit by authorities will reduce fuel loads and so limit damage from these extreme blazes.

The debate has also taken off in California, where some commentators have blamed the tragedy in Los Angeles on the decision of authorities in October to stop prescribed burning “for the foreseeable future”. The loudest voices on Australia’s east coast claim little to no prescribed burning has occurred in recent years and cite this as the reason for catastrophic fires.

Firefighters carry out a planned burn in Bendigo National Park in 2023. But do prescribed burns work?Credit: Jason South

However, each year in Victoria for more than six decades, state government agencies and fire authorities have undertaken extensive planned burns over thousands and often tens of thousands of hectares. NSW, Western Australia and all other states and territories also conduct extensive prescribed burns every year. But is this the answer, especially as there are now more large-scale wildfires in the landscape?

One of us (David Lindenmayer) was in Marysville in 2008 when the town was smothered in smoke for days from prescribed burns that spanned 640 hectares close to the town. Some residents thought they (and their homes) were protected because of these burns. Yet, almost the entire town was razed by the 2009 Black Saturday fires in which at least 34 people tragically died. The case of Marysville is far from isolated. Mapping of the current Grampians fires shows that prescribed burns covering 31,000 hectares in and around the current fire footprint over the past decade had limited effect on the spread of fires that have burnt 76,720 hectares in the past few weeks.

What does the science actually say? Do prescribed burns effectively protect people and property? A study by researchers at ANU after the 2009 fires showed a small reduction in house losses when prescribed burns were done recently and nearby. Beyond 500 metres, any benefit significantly diminished. Another study showed that rates of house loss actually increased when prescribed burns had been conducted. That’s right – an increase!

Such studies, showing what actually happened, are rare; more are needed. In their absence, authorities depend on theoretical models that use a discredited understanding of fire behaviour and potentially exaggerate the effectiveness of prescribed burning. In contrast to those models, studies of historical trends in Western Australia showed that past prescribed burns made forests less flammable in the short term, but much more flammable for decades afterward because, while prescribed burns often initially remove vegetation, they then trigger a pulse of highly flammable regrowth. It is not until forests mature that the risks of severe fires begin to subside.

Considering conditions of very high temperatures, high wind speeds, low humidity and years of drought, the fire fighting science shows that even recent prescribed burns have limited measurable and diminishing effect. Yet these extreme fire weather conditions are precisely when house loss is most likely to occur.

A structure burns during the Palisades Fire in the Pacific Palisades neighbourhood of Los Angeles, during the 2025 wildfires. Credit: Bloomberg

Beyond the limited and short-term effectiveness of prescribed burns, there are fatal side effects. Medical research shows the smoke generated by such burns kills far more people per hectare than those who die in wildfires. This is, in part, because prescribed burns are lit in calm, windless conditions and the smoke settles. A study published in the Medical Journal of Australia showed that in Sydney in 2016, smoke from planned burns led to 14 premature deaths.

The cost of prescribed burning goes beyond the loss of lives as shown in a study published in November 2024 in the international scientific journal Nature. It demonstrated that even if a recent prescribed burn makes a wildfire less severe under low to moderate fire weather, the impact of repeated fires has a much greater adverse effect on plants and animals. That is, the huge increase in fires in Victoria (including repeated prescribed burns) is having a devastating negative effect on the bush. As an example, our research in coastal Australian environments found the number of native bird species in an area declines by more than 9 per cent after each subsequent fire.

What about cultural burning as employed by First Peoples? Cultural burning and large-scale industrial prescribed burning are fundamentally different kinds of fire, for different purposes. Our First Nations mentors tell us that cultural burns were typically very small – to assist with hunting, encourage food plants, and keep walking paths open. These small, low-intensity fires amid a landscape of older forest bear no resemblance to the current regime of incendiaries dropped from planes over tens of thousands of hectares.

Instead of large-scale prescribed burning, there are better ways to prevent deadly fires. We can stop releasing fire-prone land for housing, retro-fit houses with sprinklers, intensively manage vegetation near homes, and promote the development of less fire-prone old forest. Most critically though, we need a massive increase in rapid fire detection and suppression. Many of the largest fires in recent years were tiny in their first days, but we didn’t have the technology, personnel and equipment to put them out. We can change this.

David Lindenmayer AO is a Professor at the Fenner School of Environment and Society, and has studied forests, biodiversity, fire and resource management for more than 42 years.

Phil Zylstra is an adjunct Associate Professor at Curtin University and Visiting Fellow at the Fenner School of Environment and Society. He has extensive industry experience in remote-area firefighting and management.

Dr Chris Taylor is a Research Fellow at the Fenner School of Environment and Society. He has a PhD in forest certification and extensive expertise in mapping of disturbances such as wildfires and the occurrence of animal and plant species.