Temperatures are expected to soar across large parts of the world after the UN’s World Meteorological Organisation (WMO) declared that we are in a climate-heating El Niño weather pattern for the first time in seven years.
The organisation forecasts that the event will be of “at least moderate strength” and that there is a 90 per cent probability of it continuing till at least the end of the year.
What is El Niño?
El Niño, a warming of water surface temperatures in the eastern and central Pacific Ocean, is linked to extreme weather conditions from tropical cyclones to heavy rainfall to severe droughts.
During El Niño, winds blowing west along the equator slow down, and warm water is pushed east, creating warmer surface ocean temperatures that have a knock-on effect for weather systems across much of the planet.
What does El Niño mean for temperatures and the weather globally?
The world’s hottest year on record – 2016 – coincided with a strong El Niño – and even since then climate change has fueled extreme temperatures in years without the phenomenon.
Now, putting the growing effects of climate change together with those of El Niño could result in a “double whammy”. It’s unclear how high temperatures will go and how much an effect El Niño will have – because predicting the weather is notoriously hard to do in advance because there are so many factors at play. But the weather event does increase the risk of a new global temperature record this year or next.
“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,” said WMO secretary-general Petteri Taalas.
“The declaration of an El Niño by WMO 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.
“Early warnings and anticipatory action of extreme weather events associated with this major climate phenomenon are vital to save lives and livelihoods.”
Which parts of the world will be most affected?
El Niño usually brings more flooding in the south of the US, the south of South America, the Horn of Africa and central Asia, while severe heatwaves and droughts often strike eastern Australia, Indonesia, south Asia and Central America.
During the summer, El Niño’s warm water can fuel hurricanes in the central/eastern Pacific Ocean, while it could reduce the risk of hurricanes in the Atlantic Ocean.
Generally, El Niño has the opposite effect of the recent La Niña, which ended earlier in 2023.
What about the UK?
It won’t have much of an effect on UK temperatures this summer for two reasons: firstly, because El Niño is only in its early stages of development and won’t be a powerful force until much later in the year and so it is still quite weak.
And secondly because even at full strength the effects in Europe are quite weak, as its effect is typically fairly diluted by the time it arrives over here.
Having said that, El Niño may play a small role in the UK weather next winter, increasing the chances of a windy and mild start and cold end to winter in the UK – although these are less significant than some other weather drivers, such as North Atlantic Oscillation and Arctic Oscillation, Met Office spokesman Grahame Madge told i.
“The developing El Niño will be expected to have significant impacts on the world’s weather, especially in those regions closest to the tropical Pacific. Being such a dominant force when it has fully developed towards the end of the year it can have an impact on the UK winter.
“But it is important to remember that we are a long way from the tropical Pacific so any impacts here are diluted and are subject to other drivers of weather too.
“There are associations between El Niño and the risk of a windy and mild start and cold end to winter in the UK. But these aren’t guaranteed.
“Our forecasters will take these associations into account when looking at the prospects for winter, but we also have to balance these with the influence of other drivers when producing over-winter forecasts.”
He added: “The El Niño is developing strongly but won’t be fully formed until much later in the year; therefore it is too soon for El Niño to have a significant impact on our summer.”
Simon Lee, an atmospheric scientist at Columbia University in New York, and co-editor-in-chief of the Royal Meteorological Society’s Weather journal, told i: “There is no clear link between El Niño and summer temperatures in the UK — unusually hot weather has occurred during both El Niño and La Niña. For example, last year’s heatwaves occurred during a prolonged La Niña, while the UK’s second hottest August on record occurred in 1997 during the onset of an extreme El Niño. It’s also relatively rare for an El Niño event to be well-developed during the summer, so we haven’t seen this happen many times before.”
“The lack of a strong connection between El Niño and the UK’s summer weather also contributes to making UK’s weather relatively harder to predict than in other parts of the world. In general, conditions closer to the UK — such as the exceptionally warm sea-surface temperatures in the North Atlantic — will be more important in increasing the likelihood of warmer-than-normal weather.”
