El Niño Event Expected to be Strongest in Living Memory

The Met Office has issued a warning that the El Niño event developing over the Pacific Ocean is expected to be the strongest in living memory. This powerful natural climate phenomenon is known to push up global temperatures and increase the risks of extreme weather. According to the Met Office, the combination of El Niño and human-induced climate change makes it very likely that 2027 will be the hottest year on record.

What is El Niño?

El Niño is a naturally occurring weather pattern that happens every two to seven years, lasting for around a year. It occurs when trade winds that typically blow from east to west across the Pacific Ocean weaken or reverse, allowing warm water to spread eastwards. This releases heat from the ocean into the atmosphere, lifting global temperatures and shifting rainfall patterns. An El Niño event is declared when sea surface temperatures in a key area of the Pacific are 0.5C or more above average.

Current measurements show that sea surface temperatures are well over 2C above normal, and forecasts suggest that these temperature anomalies could exceed 3C later this year. This would be unprecedented in records going back to 1950, and probably the strongest event since the 19th century. The high temperatures in the deeper ocean, around 8C above normal at a depth of 100m in some places, could help to supercharge this El Niño event.

Weather impacts around the globe

The change in the distribution of heat across the ocean and shifts in wind patterns in the atmosphere can have wide-ranging effects on the weather globally. No two El Niño events are the same, and the impacts on weather patterns can vary. However, there is evidence that the effects are already being felt, with suppressed rainfall in South Asia and reduced hurricane activity in the Caribbean and tropical Atlantic.

What effects will El Niño have on the UK's weather?

El Niño is not thought to have been a major driver of the record-breaking heatwaves that have dominated this summer. However, it could have a greater impact on the weather during autumn and early winter, with the increased potential for wet and stormy conditions across north-west Europe, including the UK. Additionally, El Niño can also increase the odds of cold weather late in the winter, although the links are rather loose.

2027 very likely to be the hottest on record

During El Niño events, significant heat is released from the ocean to the atmosphere, leading to an increase in global average temperature. According to Dr Nick Dunstone, a Met Office climate scientist, this can lead to a significant increase in global average temperature, particularly in the calendar year following the winter peak of the El Niño. As a result, 2027 is very likely to replace 2024 as the warmest year on record.