The worst combination of extreme weather patterns in the Indian and Pacific oceans will likely rise four-fold this century if greenhouse gas emissions continue on their current trajectory, leading researchers have said.

Australia's already variable climate may be particularly susceptible to a punishing sequence of events. This starts with reduced rainfall sourced off the nation's north-west, combining with a strong El Nino in the Pacific to intensify drought over the food bowl regions of south-eastern Australia, only to be followed by floods during a powerful La Nina event the following year.

Cleopatra Moir watches as shelf cloud rolls into Sydney. Credit:Nick Moir

That extreme and rare trifecta - similar to the combination that occurred during 1997-99 - will happen about once every 48 years compared with about once every 187 years in the past, research published on Tuesday in Nature Climate Change says. The research is based on more than 20 climate models.

But even weaker versions of the three elements are likely to have an amplified impact as background warming from climate change makes rainfall shifts and heatwave conditions easier to generate.