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The Bureau of Meteorology has finally declared that an El Nino weather pattern is under way, increasing the likelihood of a hot and dry summer for Australia, as global weather records continue to tumble.
The declaration comes as cloudless skies over the continent, which are typical of El Nino conditions, have seen high temperatures develop inland and flow towards the east coast, where early spring heat records have been broken.
As spring heat records are matched or beaten, the weather bureau has formally declared an El Nino weather pattern.Credit: Brook Mitchell
The event is expected to last until late summer or early autumn, said the Bureau of Meteorology’s Dr Karl Braganza during a press conference on Tuesday afternoon.
He said it was now up to individuals and communities – particularly those living in the nation’s south-east – to prepare for a summer of fire and heat hazards, but added that the landscape was not as dry as it had been leading into the catastrophic fires of 2019 and 2020.
He said global atmospheric and ocean temperatures had been at record levels since April. The event is occurring simultaneously with a so-called positive Indian Ocean Dipole (IOD), which typically sees the Indian Ocean hotter on its western edge.
“All models predict this positive IOD will persist to at least the end of spring,” the bureau said in a statement. “A positive IOD typically leads to reduced spring rainfall for central and south-east Australia.
“When a positive IOD and El Nino occur together, their drying effect is typically stronger and more widespread across Australia.”
Early indications suggest that this could turn out to be a powerful El Nino event.
“Having said that, the strength of an El Nino by those measures doesn’t necessarily correspond to the severity of the rainfall deficiencies over Australia,” Braganza said. “We have had weak events that have caused quite significant drought. And we’ve seen strong events that haven’t caused such severe conditions in the past.”
The declaration follows those by the US Climate Prediction Centre, the United Nations World Meteorological Organisation and the Japan Meteorological Agency.
The bureau’s criteria for declaring an El Nino to be under way include measurements of sea surface temperature in parts of the Pacific Ocean and the direction and strength of trade winds, which typically blow from east to west across the Pacific, leading to less moisture in the air around Australia, which contributes to reduced rains and higher temperatures.
The declaration comes after the northern hemisphere suffered through its hottest summer in history, thought to have been accelerated by an increase in the average global temperature caused by climate change.
The World Meteorological Organisation predicts that the average global temperature will be between 1.1 and 1.8 degrees higher than the 1850-1900 average over the next five years.
Global temperatures have contributed to unprecedented wildfires in Canada and Hawaii, heatwaves across Europe, catastrophic flooding in Libya and a collapse in sea ice coverage in the Antarctic.
In its statement, the weather bureau said that in August sea surface temperatures were the warmest globally for any month since observational records began in 1850, and that July and August 2023 were also respectively the hottest and second-hottest months globally in terms of two-metre air temperature.
Australia’s climate has warmed by an average of 1.48 degrees since national records began in 1910.
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