After the flood: what an El Niño might mean for Australia’s ecosystems

Climate scientists said all models at this time of year are afflicted by the "autumn predictability barrier" in the Pacific.

That means meteorologists have to wait a few months to have confidence in the forecasts, and the bureau says "outlooks through and beyond autumn should be viewed with caution".

"Heatwaves are worse and droughts are longer, deeper and harder to break," he says.

The Black Summer bushfires of 2019 and early 2020 were devastating for communities across the south and east of Australia and killed or displaced billions of native animals, pushing threatened species to the brink.

"The propensity for landscapes to burn is going to be jaw-dropping," Bowman says.

"We could unfortunately see very serious fire activity and for the public, that's very difficult to wrap your mind around when it's been so wet. But you will see these landscapes move into highly flammable states."

Bowman says the wet years have promoted grass growth, which he said was "the petrol of bushfire fuel" that burns fast and intense.

Bleaching, if severe, can kill corals. Studies have shown corals that survive and regain their colour can suffer "sub-lethal" effects such as slower growth rates, disease and less ability to reproduce.

But, as Aims and Hughes have pointed out, those same corals are the most susceptible to bleaching.