Scientists have warned that 2023 could see unprecedented heat waves due to the return of the El Niño climate phenomenon later this year.

Early forecasts suggest that this year will be hotter than 2022, which was the fifth hottest year for Europe. "It's very likely that the next big El Niño could take us over 1.5°C," said Prof. Adam Scaife of the UK Met Office.

"The probability of having the first year at 1.5ºC in the next five-year period is now about 50:50," he said.

El Niño is the natural warming of parts of the Pacific Ocean that changes weather worldwide. It is associated with an increase in temperature globally. The hottest year in recorded history, 2016, was an El Niño year.

It is a part of a larger phenomenon called the El Niño-Southern Oscillation (ENSO). El Niño is the "warm phase" of ENSO, while La Niña is its "cool phase," according to the National Geographic Society. It is typically concentrated in the central-east equatorial Pacific and its effects peak during December.

The planet is already 1.2°C warmer than in pre-industrial times, and El Niño's return is only expected to make the situation worse this year. However, there is no evidence to suggest that climate change has affected El Niño events.

But experts believe that warmer conditions created by climate change coupled with El Niño will only make the latter's impact stronger.

"You put those two things together, and we are likely to see unprecedented heatwaves during the next El Niño," added Scaife.

Its effects will take some time to kick in which implies that 2024 could be warmer than 2023. "I'm forecasting about a 15% chance of a new record in 2023. And if we're in an El Niño by the end of 2023, it's almost certainly a new record in 2024," Gavin Schmidt, who directs the Goddard Institute for Space NASA, told

hottest year 2016
Global temperature anomalies (difference from 1961-90 average) for 1950 to 2016, showing strong El Niño and La Niña years, and years when climate was affected by volcanoes. World Meteorological Organization