Climate change could cause the weather event behind many of Australia’s worst bushfires to almost triple in frequency, according to a report from the CSIRO.

It says that under current greenhouse gas emissions, an extreme positive Indian Ocean Dipole (IOD) – where sea surface temperatures are cooler than normal in the east but higher than normal in the west – will occur every 6.3 years this century, up from every 17.3 years last century.

Extreme positive IODs, which bring dry conditions to Australia through winter and spring, have preceded most major bushfires, including Black Saturday in 2009.

“This can be a strong factor in determining summer-season bushfire severity,” report author Wenju Cai told insuranceNEWS.com.au.

He says more frequent extreme positive IODs are a cause for concern, but he stresses the report findings are based on current emission levels.

“We are talking about people’s property and lives,” Dr Cai says.

“But by publishing reports like this we can raise awareness and hopefully we can avoid this situation by taking action on emissions. It is bad news, but I hope we won’t go there.”

An extreme positive IOD can hit Australia harder when combined with El Nino conditions, which bring lower rainfall and higher temperatures to southern and eastern areas.

The Bureau of Meteorology says the tropical Pacific Ocean remains “on track” for an El Nino event, with a likelihood of at least 70% this year.

Model outlooks suggest the IOD will remain neutral through winter, with two of five models suggesting a positive IOD may develop in spring.