Australia faces a return to destructive bushfire seasons as higher temperatures, less rain and record amounts of vegetation combine for potentially tinderbox conditions.
The Actuaries Institute's climate index for autumn 2023 suggests "all the ingredients are there" for higher bushfire risk, including a turn towards an El Nino phase after years of wet weather.
The quarterly Australian Actuaries Climate Index recorded its 31st positive value in a row, driven by an increase in extreme high temperatures and average maximum sea levels, accompanied by a drop in extreme rainfall.
The north and east of the country recorded more frequent extreme high temperatures in autumn, and most coastal areas recorded above-average maximum sea levels, the institute found.
After three years of wet La Nina conditions, Australia had 10 per cent less autumn rainfall overall, with less frequent extreme rainfall recorded, especially on the east, south and north coasts.
The institute said with Australia moving towards an El Nino alert phase in May and models suggesting a positive Indian Ocean Dipole will develop, there was a strong likelihood a significant dry period could begin.
“More dry weather, along with the record amounts of vegetation growth from three years of consistent wet weather, means the conditions are primed for potentially high bushfire risk in the summers ahead,” said Rade Musulin, the lead collator of the index.
“Whether that starts in early 2024 or 2025 is unknown, but we are heading in that direction. All the ingredients are there.”
Australia's most recent destructive bushfire season was the Black Summer of 2019-20, which scorched more than 24 million hectares and directly killed 33 people.
Mr Musulin said while he expected significantly high summer temperatures, it was too early to say whether Australia would bake under extreme heatwaves similar to those that have gripped the northern hemisphere in places such as southern Europe and the United States.
He also warned the index showed signs that Australia's underlying climate had changed, indicating a longer-term trend of an increasing frequency of extreme weather.
“What the climate index is showing us is consistent with the warming climate,” Mr Musulin said.
