The world’s climate change authority has underestimated the extent and intensity of future Australian bushfires, according to a new study.

The International Panel on Climate Change’s sixth report last year predicted a longer fire season in Australia and a greater number of dangerous fire weather days.

But a new report in the International Journal of Wildland Fire suggests that communities will also face more multi-day fires, with limited opportunity to control the fires overnight, compared to current climate projections.

Central to their concerns are how the IPCC predictions rely on a tool called the Forest Fire Danger Index (FFDI), which does not capture the full potential of future fires in drought and heatwave conditions.

Bureau of Meteorology senior research scientist Mika Peace and independent study co-author Lachlan McCaw identified several variables missing from the IPCC report’s fire predictions under climate change.

To do this the pair analysed processes that drove some of the devastating Black Summer bushfires around the country in 2019–20.

The missing factors

Australia replaced the FFDI and a Grass Fire Index for its bushfire warning system in 2022, but the FFDI has still been used in long-range climate projections.

The index takes variables like temperature, relative humidity, wind speed and fire fuel availability related to drought.

Data is usually taken from the middle of the day when heating is assumed to be at its highest.

But Dr Peace said this did not capture what was seen in big fires like Black Summer where there were active fires overnight.

 Bushfires are predicted to become more intense overnight. This was a factor in many of the Black Summer fires such as the Green Valley Talmalmo/Corryong fire (pictured).(Supplied: Amber Rendell)

She said one of the factors exacerbating future fires, not taken into account by the IPCC, were low-level surface winds called ‘jets’ that could drive overnight fire spread.

“In the same way that we see the jet streams at the top of the atmosphere, which people are often in, if they’re in a plane … we can also get these low-level jets developing near the surface,” she said. 

“These are the winds or the energy that the fire plume can tap into.”

Other factors included an increased risk of fire-generated thunderstorms, changes to vegetation, and more fuel for fires because of heatwaves and droughts.

Bureau of Meteorology fire weather forecaster Mika Peace.(Supplied: Bureau of Meteorology)

Rick McRae from UNSW’s bushfire research group agreed with the study’s claim fires would be worse than long-range forecasts and IPCC reports.

But he said the authors took too narrow a view, and there were further influences on extreme fires than the ones listed.

“Detailed observations show that even this paper is underestimating the problem,” Dr McRae said.

“We have already exceeded many long-range forecasts. And we show no signs of slowing.

“The pyroCb [Cumulonimbus flammagenitus, which are storms often caused by wild fires] count in Australia is literally growing exponentially.”

University of Melbourne bushfire risk researcher Hamish Clarke commented the authors were right to caution against assessing future fire conditions based solely on fire indices like the FFDI.

“While these metrics often do an admirable job at predicting a range of fire-related risks, they don’t tell the whole story,” he said.

“Fire is complicated and if we’re going to successfully live with it in a warming world we need to draw on insights from a range of perspectives – certainly meteorology, but also ecology, engineering and many others, including social science and the humanities.

“We need to listen to Indigenous fire knowledge holders.”

Dr Clarke said there would hopefully be better metrics in the future which took into account some of the missing factors raised by the new study.

The cost of more damaging fires

Study co-author Dr McCaw said he thought with a more challenging future fire environment it would require a greater investment in fire management and associated weather services.

“Some of this will be to provide fire response but equally important will be maintaining and enhancing capability to manage land to make it less vulnerable to fire,” he said.

“This includes actions such as fuel management with planned burning, providing good access to reach fires before they become problematic, and better preparing communities for fire.

“Current bushfire response relies heavily on volunteers and this capability will be stretched by longer duration fire events that require continuous operations day and night across multiple days.”

National expenditure on fire and emergency services in states and territories has increased 32 per cent in the past 10 years from $4.5–$5.9 billion.

But the year of Black Summer cost the country a record $6.4 billion.

WA Department of Fire and Emergency Services rural fire executive director Murray Carter said on-the-ground fires were running harder at night than they had before.

“I think it’s been like that for 8 to 10 years at the noticeable level,” he said.

“It might have started before that but just those opportunities for night time suppression have disappeared over the past decade.

“I think what it speaks to is we need to not only be well equipped, trained and geared up to respond to more fires and intense fires, but we have to do more in the risk-management space.”

DFES executive director rural fire Murray Carter says planned burns are probably one of best preparations you can make to keep the WA community safe.(ABC News: Nicolas Perpicth)

Queensland Rural Fire Service assistant chief officer Joel Gordon said the service was investing more in firefighting capability but also research on the different conditions in different landscapes across the state.

“From our point of view, we’re taking a proactive approach and we’ve invested in bushfire science research,” he said.

“As well as innovation and development in relation to new firefighting appliances, new firefighting equipment, the use of technology, drones and, and other key innovations to help actually enhance our firefighting operations.”

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