WMO declares El Niño underway, increasing chance of record high global temperatures

The World Meteorological Organization (WMO) has declared El Niño is now underway, increasing the likelihood of record high global temperatures and disruptive weather patterns over the next 12 months.

The agency’s announcement on Tuesday marks eight years since the last El Niño developed, which began in 2015, and ended in 2016.

“The collective evidence from both oceanic and atmospheric observations strongly points towards the presence of El Niño conditions in the Pacific,” it read. 

The WMO update combines forecasts and expert guidance form around the world and follows similar declarations made by several national agencies earlier this year, including the USA and Japan.

While Australia is historically one of the nations hardest hit by El Niño, weather patterns have so far not shifted in our region, and rainfall has been widespread through the past two weeks.

El Niño refers to a change in weather patterns around the world resulting from a tongue of warmer than average sea surface temperatures across the equatorial Pacific Ocean.

The impacts of El Niño typically last nine to 12 months, varying from region to region, and its arrival comes with warnings of extreme weather events.

“The onset of El Niño will greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean,” WMO secretary-general Professor Petteri Taalas said.

“The declaration … is the signal to governments around the world to mobilise preparations to limit the impacts on our health, our ecosystems and our economies,” he said.

The last fully fledged El Niño ended seven years ago, and in conjunction with human-induced global warming from greenhouse gases, caused 2016 to become the hottest year on record.

This year is already on track to challenge that record.

However, El Niño’s effect on global temperatures is most prominent the year after development, so 2024 is more likely to surpass those 2016 temperature levels.

It could also become the first year to temporarily pass the 1.5 degrees Celsius level specified in the Paris Agreement.

While the WMO is now satisfied El Niño conditions are present, the Bureau of Meteorology (BoM) held its El Niño status at one level below a full declaration on Tuesday.

This was due to an absence of an atmospheric response to the Pacific warming.

Essentially, the Bureau is waiting for the changes in ocean temperatures to have a greater impact on the weather.

This more conservative approach taken by the Bureau is likely to be short-lived according to the WMO, which expects El Niño weather patterns to become more prominent this winter.

“Some uncertainty remains because of only weak ocean-atmosphere coupling, which is crucial for the amplification and sustenance of El Niño,” the WMO’s statement read.

“It is anticipated that it will take approximately another month or so to witness a fully established coupling in the tropical Pacific.”

Historically, El Niño brings below average rain and above average temperatures to Australia, particularly through winter and spring, which can lead to severe drought and enhanced bushfire activity.

This year the delayed onset of typical El Niño weather has so far negated impacts. June rainfall has been 25 per cent above average, followed by a wet start to July throughout much of Australia.

Despite the BoM’s reluctance to declare El Niño, its seasonal outlooks already indicate below average rain and above average temperatures are the most likely outcome into late winter and spring.

While the forecasts appear grim, not every El Niño brings severe drought, as per the previous El Niño, which only brought dry conditions to small pockets of Australia.

Another reason why the warm and dry forecast may not eventuate, is a separate dry signal predicted from the Indian Ocean has so far failed to materialise this winter.