A key global climate target is likely to be temporarily breached for the first time during the next five years, the UN’s World Meteorological Organisation (WMO) is warning today.

Several major climate organisations now say that the world could be entering a climate phase known as El Niño — a natural phenomenon which, combined with human-induced climate breakdown, is almost certain to bring devastating new global heat records and extreme weather.

So, what is El Niño and what could it mean for the world? FactCheck takes a look.

What is El Niño?

El Niño is a term used to describe a natural climate pattern where sea surface temperatures temporarily rise, especially in the tropical central and eastern part of the Pacific Ocean.

El Niño can last for a few years and, despite being most concentrated around the Pacific equatorial seas, has enormous impacts on weather patterns around the world — affecting rainfall, drought, heatwaves and everything these then influence in turn, including food production.

An El Niño phase can last a few years at a time, and is broadly linked with temporarily raising global temperatures. But it can also fluctuate to an alternative, colder climate phase called La Niña, which may also last several years.

“El Niño and La Niña, that cycle in the Pacific, are the biggest natural form of climate variability there is,” Professor Adam Scaife from the UK Met Office explained to FactCheck. “It’s been going on for thousands of years, and every few years it flops one way and the next.”

The world has been in the cooler La Niña since 2020, but scientists now expect this to switch into El Niño in the coming months — bringing potentially record breaking temperatures with it.

Earlier this month the WMO warned that there was a 60 per cent chance El Niño would emerge before July and an 80 per cent chance by September.

Is El Niño linked to climate change caused by humans?

While El Niño is a natural part of the global climate system, it now comes on top of the much greater heating effects of human-caused climate change.

In a report published today, the WMO said it expects the incoming El Niño to combine with climate change to the extent that, for the first time, there is a 66 percent chance that global temperatures will rise by more than 1.5 celsius above pre-industrial levels for at least one of the next five years. Limiting global warming to 1.5 degrees is one of the main goals of the Paris climate agreement.

In a press conference The Met Office, which led the WMO study, said that breaching the 1.5 degree Paris target in a single year, rather than as a long term average, would not mean that goal is broken — but would underscore that the world is failing to curb global greenhouse gas emissions.

The likelihood of exceeding the 1.5 degree Paris threshold was around 50 per cent just one year ago. But the large increase in probability to 66 per cent in such a short period was partly due to the continued increase in global greenhouse gas emissions, the Met Office added.

The report said that the climate crisis combined with El Niño means there is a 98 per cent chance that one of the next five years will be the hottest ever recorded.

What are the likely impacts of El Niño?

The clearest impact of El Niño is the temporary rise in global temperatures. The hottest year ever recorded was in 2016 during a major El Niño event.

But less obvious are its effects on other parts of the global weather systems.

“In terms of the UK, there is an impact,” Professor Scaife told Channel 4 News. “It’s not enough to determine the outcome of the weather in the UK, but it does shift the probability. So if we have an El Niño it is more likely we’ll have cold snaps, particularly in late winter — January, February or March. That’s been shown through many studies. “

Today’s WMO report predicts that the incoming El Niño will lead to more rainfall in Northern Europe, at the same time as reduced rainfall and droughts in southern hemisphere countries like South Africa and Australia.

“We know that El Niño has enormous impacts in certain parts of the world, including on food security,” Professor Scaife said.

For example, there is a significant risk that El Niño can interrupt the monsoon season on the Indian subcontinent which can both lead to climate disasters and loss of life, but also wreck rice production which feeds much of the world.