UK forecasts 'biggest' El Nino will smash records, spark hottest year

This year's El Nino weather pattern will be the biggest in over a century and could make 2027 the hottest year globally, Britain's national weather agency predicted Friday.

An El Nino weather event happens when warming sea surface temperatures in the tropical eastern Pacific trigger worldwide changes in winds, atmospheric pressure and rainfall, as well as higher global temperatures overall.

Adam Scaife, head of long-range forecasting at the weather agency, told the BBC: "We are expecting the biggest El Nino for over a century, peaking at something over 3 degree Celsius – that is unheard of in modern climate records." This means Pacific water would heat up more than 3 degree Celsius above the norm in the coming months.

El Nino occurs when water temperatures rise at least 0.5 degree Celsius above the baseline.

While it is part of a natural cycle, scientists agree climate change increases its impacts.

A record El Nino would be "adding to the stresses of climate change" following a summer of heat waves across Europe, the Met Office said in a blog.

Temperatures in the Pacific region are currently running about 2.6 degree Celsius above a rolling 30-year average, according to the Climate Brink dashboard based on data from the US National Oceanic and Atmospheric Administration.

The dashboard also aggregates forecasts that put El Nino on course to peak at a 3.9 degree Celsius anomaly this November – well above a 3 degree Celsius anomaly detected in 2015.

"We should be clear that this is an unprecedented event," British scientist Scaife said in a Met Office blog.

If the forecast is accurate, then 2026 "will far exceed our recent experience of El Nino and its worldwide climate influences," said the physicist who specialises in climate modelling.

"I have never seen an El Nino signal this intense in our forecasts," he added, with even a 2-degree Celsius rise considered a "really big event." El Nino typically results in drier conditions across southeast Asia, Australia, southern Africa and northern Brazil, and wetter conditions in the Horn of Africa, the southern United States, Peru and Ecuador.

This year's anomalous warmth will have particularly strong effects throughout the Tropics, Scaife said.

Forecasters "expect really severe droughts in places like South America, and the West Pacific," he added.

El Nino is already causing well below normal rainfall in India, the Met Office said.