Wild weather, floods, monster cyclones and mosquito-borne viruses could be heading Australia’s way after a summer of bushfires and the COVID-19 year from hell.
Prime Minister Scott Morrison and state premiers will be briefed on the risk of an intense La Nina weather pattern emerging at Friday’s national cabinet.
La Nina is the weather pattern that delivered Cyclone Yasi to Queensland in 2011, one of the strongest to ever hit Australia bringing peak wind gusts estimated at 285 kilometres per hour.
The wet conditions it brings also increases the likelihood of an outbreak of mosquito-borne diseases such as Ross River virus, which is spread by the bite of infected female mosquitoes.
Cyclone Tracy, which wiped out much of Darwin in 1974, killing 71 people, also occurred during an intense La Nina cycle as did tropical Cyclone Larry in 2006.
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WHAT IS LA NINA?
During La Nina, there are not only more tropical cyclones, but more make it to landfall and the first cyclone to cross the Australian coast also tends to occur earlier in the season.
In August, the Bureau of Meteorology raised its El Nino-Southern Oscillation Outlook to La Nina ALERT status, meaning the chance of a La Nina occurring this year has increased to 70 per cent.
Announcing the risk alert last month, the BOM said that doesn’t guarantee Australia will reach La Nina thresholds but it does mean experts believe there’s roughly three times the normal likelihood of a La Nina occurring in coming months.
“It typically also brings cooler and cloudier days, more tropical cyclones, and an earlier onset of the first rains of the wet season across the north,” the Bureau’s Manager of Climate Operations, Dr Andrew Watkins said.
“The cooling of surface temperatures in the tropical Pacific Ocean and an increase in the strength of the Pacific Trade Winds indicates the chance of La Nina has risen. When these two changes occur at the same time, at this time of year, we see a greatly increased chance of a La Nina forming and persisting through spring.
“Climate models suggest that further ocean cooling and intensification of Trade Winds may occur over the coming months, which has triggered the Bureau to shift from a La Nina Watch, issued on 26 June, to a La Nina Alert.”
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Some experts have previously argued the risk of extreme La Nina events in the Pacific Ocean could double due to global warming.
Recent research has predicted the extreme La Nina weather pattern could occur every 13 years, rather than the 23 years previously seen.
The last La Nina event in Australia was just ten years ago, when there was widespread flooding across southeast Australia.
La Nina is the opposite of the El Nino pattern that occurs when the surface of the ocean warms and typically results in more droughts and fires in Australia.
The La Nina and El Nino effects are sometimes described as the “cold” and “warm” phases of fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific.