All the ingredients are in place for high bushfire risk in the summers ahead, according to the latest Australian Actuaries Climate Index.

The latest index shows conditions are “ripening” for a return of destructive bushfire seasons in Australia, with a significant drop in recent extreme rainfall and a rise in extreme temperatures. 

Covering autumn, it shows the beginnings of conditions that could eventually be conducive to strong bushfires, the Actuaries Institute says, driven by high levels of fuel availability after several years of wet weather - and a return to a dryer, hotter El Nino phase and a likely positive Indian Ocean Dipole. 

“Conditions are primed for potentially high bushfire risk in the summers ahead,” Australian Actuaries Climate Index Lead Collator Rade Musulin said. 

“Whether that starts in early 2024 or 2025 is unknown but we are heading in that direction. All the ingredients are there.”

Mr Musulin expects significant temperatures to be recorded in Australia this summer.

“It would be premature to say Australia is heading into heatwaves like those we’re seeing in places like Athens and Texas but given what … the Australian Actuaries Climate Index is telling us, it’s certainly time to be vigilant.” 

The Bureau of Meteorology declared an El Nino “alert” in May. In the past, an El Nino event has then developed around 70% of the time, bringing below-average rainfall over much of Australia. It is the opposite of La Nina which is waning after a three-year reign that brought record floods.

There is a strong likelihood that rainfall will continue to decline and a significant dry period may begin, the Actuaries Institute says. Climate models also suggest that a positive Indian Ocean Dipole is likely to develop in late winter or early spring, which tends to suppress rainfall over central and south-east Australia. 

“The large quantities of available fuel that have resulted from several consecutive wet years combined with the drying out brought on by a likely El Nino phase has the potential to create conditions conducive to high bushfire risk in coming years,” the Actuaries Institute said.

“This may take time to eventuate due to the significant amount of moisture that has accumulated in the soil in recent years.”

The institute launched the index in 2018 to measure extreme weather conditions and changes to sea levels. It measures any exceedance of the 99th percentile of the 1981-2010 reference period to gauge changes in the extremes – a more relevant metric than averages for the insurance industry as it correlates with damage.

Mr Musulin says the index provides a strong signal that the underlying Australian climate has changed.

“It shows a longer-term trend of an increasing frequency of extremes,” he said. “We need to think about how these things develop over time. What the Climate Index is showing us is consistent with the warming climate.”