The past two El Niño events – in 2014-16 and 2023-24 – brought record heat around the world that fueled further global temperature increase.

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El Niño, a climate phenomenon related to the warming of sea surface temperatures in the central-east equatorial Pacific, is set to return in 2026, throwing weather patterns worldwide out of whack, scientists have warned.

According to an advisory issued last week by the National Oceanic and Atmospheric Administration (NOAA), El Niño is likely to form during the summer months and persist through the end of 2026 and potentially longer, with a 1-in-3 chance of becoming “strong” in the winter months. It marks a notable revision upwards from previous forecasts that suggested a modest El Niño might develop.

During an El Niño event, the east-to-west trade winds die, keeping warmer than the normal air in the eastern and central parts of the tropical Pacific. The associated warming in the central and eastern tropical Pacific leads to increased temperatures and opposing weather patterns around the world, such as severe droughts in places like Australia and Southeast Asia and heavy floods in parts of the US and East Africa.

The past two such events – in 2014-16 and 2023-24 – brought record heat around the world that fueled further global temperature increase. 2024 went down as the hottest year on record due to a combination of long-term human-caused climate change and a strong El Niño weather pattern. Now, its return increases the chances of another record warm year – likely to be 2027, according to climate scientist Zeke Hausfather.

“We know that under climate change, the impacts of El Niño events are going to get stronger, and you have to add that to the effects of climate change itself, which is growing all the time,” Professor Adam Scaife, the head of a long-range prediction at the UK Met Office told the Guardian in 2023. “You put those two things together, and we are likely to see unprecedented heatwaves during the next [event].”

El Niño and La Niña are opposite phases of the El Niño Southern Oscillation (ENSO), a temperature variation between the ocean and the atmosphere over the east-central Tropical Pacific. The first is a warm phase while the latter is the cold phase. They typically occur once every few years, lasting nine to 12 months but sometimes even years. Their frequency is quite irregular, and the warm phase happens more frequently than their counterpart.

Featured image: Kyle Lam/hongkongfp.com.

More on the topic: The Impacts of a Changing Climate on the El Niño-Southern Oscillation