After a mild winter and an unusually warm start to spring (26 degree days in September? In Melbourne? Unheard of), the news we had both been dreading and anxiously anticipating has arrived: the Bureau of Meteorology (BoM) has just announced Australia has entered into an El Niño weather pattern.
It seems like only yesterday that El Niño’s soggy sibling, La Niña – a cold weather phenomenon characterised by cooler temperatures, damp conditions, increased rainfall and flooding – was run outta town, and now we’re facing a summer of severe heat. So what exactly does it all mean? And just how bad are things (potentially) going to get? Here’s everything you need to know about El Niño.
What is El Niño?
El Niño – which translates to ‘little boy’ in Spanish – is a naturally occurring climate pattern that results in warmer than average sea surface temperatures in the eastern Pacific Ocean, a weakening of trade winds and a shift in atmospheric circulation.
In Australia, this results in hotter temperatures (and more individual days of extreme heat), plus an elevated risk of drought and bushfires. It’s also a key factor driving climate change.
Now for the double whammy: the BoM has also declared that a positive Indian Ocean dipole (IOD) event is happening. This is a climate phenomenon that usually unfolds in late autumn or winter, and results in decreased rainfall. Essentially, when these two weather patterns combine, it creates conditions similar to what we experienced during the devastating summer of 2019/20 when bushfires tore through parts of Victorian and New South Wales.
How long does El Niño last?
An El Niño weather pattern usually last for nine to 12 months, but the effects can linger on for up to two years. This current El Niño phase is expected to last until at least the end of February, 2024.
The last El Niño in Australia happened in 2018/19, with the Black Summer bushfires of 2019/20 a direct result of the severe conditions. It also didn’t help that 2019 was the hottest and driest year recorded in Australian history.
How often does El Niño occur?
El Niño cycles typically occur every three to five years. The most recent event happened in 2018/19 and prior to that it was the summer of 2015/16.
What can we expect from El Niño in Melbourne?
Melburnians are in for warmer temperatures across the second half of the year, with reduced rainfall and prolonged warm spells. Cloudless skies can also increase the frost risk during early morning periods.
While three years of wet, damp conditions thanks to La Niña means that the landscape is not as dry as it could be, there has been plenty of grass and vegetation growth which has the potential to become fuel for fire. Because of this, there is the chance of an elevated bushfire threat.
Is El Niño affected by climate change?
While El Niño and La Niña events are generally governed by Mother Nature, a recent study by researchers at the CSIRO confirmed that a rise in greenhouse gas emissions has resulted in increased frequency and ferocity of these two weather patterns. There’s also been a particular uptick in El Niño and La Niña events since the 1960s.