La Niña is rapidly easing, the BOM says. But the prospect of El Niño has some worried. So what’s next?

Home Politics La Niña is rapidly easing, the BOM says. But the prospect of El Niño has some worried. So what’s next?
La Niña is rapidly easing, the BOM says. But the prospect of El Niño has some worried. So what’s next?

It looks as though La Niña’s three year grip as the prevailing climate driver for Australia’s east coast could be over. 

The Bureau of Meteorology (BOM) has updated its latest outlook which suggests La Niña may be easing. 

Now there’s a possibility that Australia could face an El Niño event later this year, which has some worried. 

What’s happening? 

La Niña appears to be weakening faster than usual. 

It’s the climate driver generally responsible for cooler, wetter conditions.

For the past three years it has been the dominant climate driver in the El Niño Southern Oscillation (ENSO). 

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Potential El Nino event developing as La Nina weakens

That has coincided with widespread flooding across Australia in the past couple of years. Flooding continues in South Australia.

It now appears that the weather driver which results in wetter conditions is easing rapidly, says BOM meteorologist Pieter Claasen.

“We are still very much in the La Niña phase even though it is weakening quite rapidly, it probably won’t last too much longer,” he said.

“Certainly, it looks like the La Niña will decay earlier than typical, it’s already started to decay and may return to neutral shortly.”

The latest BOM outlook, released on Wednesday, suggests there is a chance that could change next summer. 

But while there is the possibility of an El Niño event, the BOM says it could be months before we have a good idea about what might happen. 

“ENSO outlooks that extend through autumn should be viewed with caution,” the weather outlook reads.

Mr Claasen says it’s just too early to tell whether Australia’s east coast will be impacted by El Niño.

“It’s not really until late summer, early autumn that we really get a clearer picture of exactly what’s coming,” he said.

“There is a bit of a barrier to predictability that occurs at this time of year to be able to accurately forecast the next phase of the ENSO cycle.”

Lots of people gathered at Noosa main beach with umbrellas
The tail end of summer could be clearer than the past few years, as La Niña eases earlier than usual.(Supplied)

He says La Niña’s early decline means the rest of summer could be clearer compared to the past few years in some parts of the country.

“Our rainfall outlook isn’t as strongly wetter than average as it has been for the last few years,” Mr Claasen said. 

“For much of Queensland, the rest of summer is looking neutral to slightly above neutral conditions.

“So not that really strong signal that we’ve seen in the past with these outlooks, where it’s been something like 80 per cent likelihood of exceeding median rainfall.

“Now it’s more like 50 to 60 per cent chance it will exceed median rainfall.”

Read more: What is the La Niña and what does it mean for Australian weather?

So, what’s an El Niño?

It’s the brother system of La Niña. 

For Australia, El Niño typically leads to drier and hotter conditions, while La Niña usually leads to cooler and wetter conditions.

Map of the Pacific ocean with counter clockwise arrows indicating air flow and reduced chance of rain for Australia
When there is an El Nino the Walker Circulation is reversed and downward pushing air brings dry conditions to Australia(Supplied: Bureau of Meteorology )

It’s complicated, but the weather drivers depend on water temperatures in the Pacific Ocean. 

There’s also a neutral phase between the pair. 

“[ENSO] could go back to neutral,” ANU climatologist Professor Janette Lindesay told the ABC.

“That’s another thing a lot of people don’t realise, that conditions in the Pacific don’t have to be El Niño or La Niña.

“They can just be neutral with nothing going on.” 

Read more: What El Nino and La Nina actually mean for Australian and world weather

Give me a little more detail on what causes an El Niño?

El Niño is the result of extensive warming of the central and eastern tropical Pacific Ocean, near South America. 

This can lead to a major shift in weather patterns across the Pacific.

For Australia this means more cooler water pools off the east coast. 

And, generally speaking, that leads to less evaporation from the ocean, less moisture in the atmosphere, and less rain over Australia.

Read more: Drier weather on the cards in latest BOM update as Indian Ocean Dipole switches to neutral

Why are some people worried?

Because the drier conditions can bring about drought, or worse. 

Black clouds with a mushroom formation above dry farmland
Farmers in some parts of the country say they’re already experiencing drier conditions.(Supplied: Yvonne Poole)

El Niño conditions resulted in the record-breaking drought from 2017 to 2020. 

And the last El Niño Australia experienced coincided with catastrophic Black Summer bushfires in 2019/20. 

Farmers in some parts of the country say they’re already experiencing drier conditions.

Read more: Australia’s Black Summer bushfires were catastrophic enough. Now scientists say they caused a ‘deep, long-lived’ hole in the ozone layer

So, how likely is it that we’ll get an El Niño?

Professor Lindesay puts the chances of a El Niño developing at about 65 per cent. 

“Now the current outlook for the rest of this year is that there’s the potential for an El Niño event to develop once we get to June of 2023,” she said.

“If we do get an El Niño coming up after this La Niña – and there’s no guarantee of that – there’s about a, sort of, 65 per cent chance we’re looking like an El Niño event.”

Dry conditions in NSW
In a few months we’ll have a clearer picture on whether Australia could be facing an El Niño summer. (ABC News: Nick Grimm)

Professor Lindesay said an El Niño declaration doesn’t necessarily mean drought conditions, adding there are a number of variables at play that impact rainfall. 

Like the weather bureau, she said we would have a better picture of the outlook in a few months.

“That then gives us the months through winter and spring to manage the consequences if it is indeed an El Niño event,” she said.

“And some of those consequences could include the below average rainfall and above average temperatures, and when you’ve got that combination, then we’re looking at quite serious bushfire risk.

“We’re coming out of a period where we’ve had three years of above average rainfall, there’s a lot of fuel out there, and it doesn’t take very long with no rain and high temperatures for that fuel load to dry out.

“It just takes a spark to start a fire, and that’s something we need to be extremely mindful of as we go through this year.” 

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