Key Points
- The Bureau of Meteorology has declared an El Niño event is likely to happen this year.
- It will remain at an alert stage for another fortnight.
- An El Niño event could increase the risk of drought, heatwaves, and bushfires.
An El Niño event remains likely for Australia but the weather bureau has stopped short of declaring it will definitely happen.
The Bureau of Meteorology (BoM) on Tuesday released its latest climate driver update, stating an is "considered likely" in the coming weeks.
But the forecast will remain at an alert stage until the next update on 15 August.
"When El Niño alert criteria have been met in the past, an El Niño event has developed around 70 per cent of the time," the BoM said in a statement.
El Niño conditions could contribute to conditions for bushfires in Australia, climate scientists have warned. Source: AAP / Jono Searle
The BoM said sea surface temperatures in the tropical Pacific Ocean are currently exceeding the thresholds needed for an El Niño event, but the atmosphere patterns are pointing toward more neutral conditions.
"The Pacific Ocean and atmosphere have yet to become fully coupled, as occurs during El Niño events," the BoM statement said.
How would an El Niño impact Australia?
An El Niño event could increase fuel availability, ignition likelihood, and , particularly in eastern Australia, said Hamish Clarke, a professor of ecosystem sciences at the University of Melbourne.
"The effects won’t be the same everywhere and El Niño is not the only climate driver that influences bushfire risk, there’s also the Indian Ocean Dipole and the Southern Annular Mode."
He said any additional warming we see as a result of El Niño this summer wold come on top of decades of which has "already significantly raised temperatures and bushfire risk in many areas".
"Without much stronger climate action than we are currently taking, we can expect to see much worse conditions in the future," he said.
Climate modelling suggests surface temperatures in the Indian Ocean will change in late winter or early spring, bringing less rainfall in winter and spring and exacerbating the drying influence from El Niño.
Regardless of the latest climate driver statement, the BoM is continuing to forecast warmer and drier conditions across the country between August and October.
Meteorologist Milton Speer said it will be important to track the state of the Southern Annular Mode (SAM) — another climate driver.
"Periods of negative SAM are conducive to dry, warm westerly winds affecting the east coast thereby leading to extreme coastal maximum temperatures.
"The SAM typically varies on time scales of a few weeks but has trended positive in summers during recent decades."
That implies humid onshore breezes increasing the discomfort factor which is dangerous for human health, he said.
The BoM uses four interrelated indicators, three of which have met El Niño alert thresholds, including the Southern Oscillation Index (SOI).
Professor Janette Lindesay, a climatologist at the Australian National University, said the SOI "has been negative in several individual recent months, but has not been consistently negative to the extent required to indicate an El Niño".
"In 2023 this could be linked to above-average sea surface temperatures around north-eastern Australia," she said. "This anomaly is likely related to ongoing ocean warming due to global heating."
