Australia is on alert for El Niño after the Bureau of Meteorology declared a 70% likelihood of the weather event developing later this year.
It follows May predictions by Chinese meteorologists for a more intense El Niño later this year, and the US National Oceanic and Atmospheric Administration estimates a greater than 90% chance of the phenomenon persisting into the northern hemisphere winter.
El Niño and its twin phenomenon La Niña are natural fluctuations in Pacific Ocean trade winds altering the movement of water along the equator.
These in turn result in variations in rainfall patterns and temperatures across regions of the Pacific.
Australia experienced a rare ‘triple dip’ La Niña from 2020 to 2022, which saw rainfall records for the continent’s east coast tumble.
In contrast, El Niño deals Australia a range of summer-like conditions: reduced rainfall for the eastern states, warmer temperatures south of the tropics, and heightened risk of extreme heat, bushfire danger, overnight frosts and snow decline in alpine regions.
The Bureau also anticipates drier and warmer climate conditions across most of the country throughout winter.
“The climate conditions in the Pacific Ocean are already factored into our forecasts,” says senior bureau climatologist Catherine Ganter.
“The long-range forecast for winter also shows an increased chance of below average rainfall for almost all of Australia and the move to El Niño Alert does not change this forecast.”
Although an El Niño Alert is only marked by 70% probability, natural hazards research scientist at the CSIRO’s Data 61 centre Dr Nandini Ramshe says the consequences of a confirmed El Niño may not be clear on strength alone.
“The change from an El Niño Watch to an Alert indicates that forecasts are now confident that an El Niño is developing, as we have moved beyond the uncertain autumn period,” Ramshe says.
“Warm water temperatures have spread across the crucial eastern-central tropical Pacific region, but the muted response from the atmosphere at this stage makes it difficult to know how strong the El Niño event will be.
“But how strong the impacts are on Australia are not obvious from the strength of the event – some of the worst bushfire seasons in Australia have been during weak to moderate El Niño events like 2019-20 rather than strong ones like 2015-16.”
Even moderately hotter and drier conditions could have a catastrophic impact in terms of bushfires, with higher than usual vegetation regrowth after three years of increased rainfall. In January, former Fire and Rescue NSW commissioner Greg Mullins, who now heads up not-for-profit Emergency Leaders for Climate Action, warned of the danger presented by post-La Niña fuel supply.
“Excessive rainfall in recent years has caused prolific vegetation growth in Australia, which is now drying and turning into fire fuel as we experience hotter, drier conditions,” Mullins said.
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