Unprecedented El Niño event expected to push 2027 to hottest year on record
The Met Office has warned that the Pacific Ocean phenomenon is likely to become the strongest since records began, raising global temperatures and increasing risks of extreme weather.
The El Niño event developing over the Pacific Ocean is likely to become the strongest in living memory, the Met Office has warned, with sea surface temperatures already well above normal and forecasts suggesting anomalies could exceed 3C later this year. Such a figure would be unprecedented in records going back to 1950 and probably represent the most powerful event since the 19th century, according to scientists.
The natural climate phenomenon, which occurs every two to seven years and typically lasts for about a year, pushes up global temperatures and can increase the risks of extreme weather. Added to the effects of human-induced climate change, the Met Office has said it is "very likely" to mean 2027 will become the hottest year on record globally, surpassing 2024. Earlier this month, the UN's Food and Agriculture Organization warned that El Niño could threaten tens of millions of people in at-risk countries with crisis-level acute food insecurity.
Current measurements show sea surface temperatures in a key area of the Pacific are well over 2C above average, with some depths recording temperatures around 8C above normal at 100 metres. This reservoir of warm water could help to supercharge the event, said Dr Zeke Hausfather of Berkeley Earth, a US research group. "We have many months to go while this event continues to develop, and that's one of the reasons that we have increased confidence that this will be a record-setting event," he said. Some other climate groups have projected anomalies even higher than the Met Office's forecast, perhaps 4C above average, which Dr Hausfather said could make it the strongest El Niño in 500 or even 1,000 years.
Prof Adam Scaife, head of long-range forecasting at the Met Office, said: "I have never seen an El Niño signal this intense in our forecasts." There is no clear evidence that climate change is making El Niño events worse, according to the World Meteorological Organisation and the Intergovernmental Panel on Climate Change, though the IPCC has said their intensity has increased since 1950 compared with the period dating back to around 1400. What is clear is that El Niño is now unfolding against a warmer backdrop, making its weather impacts more extreme.
Evidence of its influence is already emerging. Below-average monsoon rains in India and suppressed hurricane activity in the Atlantic—with only three named storms so far this season—are consistent with El Niño patterns. For the UK, the phenomenon could bring a wet, stormy autumn, with signs of an unsettled spell already showing in long-range forecasts. El Niño can also increase the odds of cold weather late in the winter, though the links are loose.
The shift in ocean heat distribution and atmospheric wind patterns can have wide-ranging effects globally. Drought and bushfire risks rise in Australia, while flooding threats increase in Peru, Ecuador and the southern United States. Dr Nick Dunstone, a Met Office climate scientist, explained that significant heat is released from the ocean to the atmosphere during El Niño, leading to "an increase in global average temperature, particularly in the calendar year following the winter peak of the El Niño. Hence, 2027 is very likely to replace 2024 as the warmest year on record."