An intensifying El Niño broke a temperature record in a key zone of the Pacific Ocean in September, the European Union's climate monitor said on Monday, in another sign that the weather pattern is gaining exceptional strength. Forecasters have warned for months that this El Niño could become the strongest ever observed, and the latest record has fallen even before the event's expected peak later this year.
The Copernicus Climate Change Service said sea surface temperatures in the Niño3.4 region, a tell-tale area used to monitor El Niño in the Pacific, reached an "all-time high" of 29.70C last month. That exceeded the peaks of earlier strong events in 1982/1983, 1997/1998 and 2015/2016, "underscoring the exceptional intensity of the current El Niño", the agency said. Japan's weather agency separately said on Friday that El Niño conditions had reached their "strongest intensity on record", with temperatures in its monitoring area 4C above normal.
Copernicus was careful, however, not to go further. It said it "cannot yet say that the current El Niño is the strongest ever recorded". Because climate change is warming the oceans, recent events can look stronger than older ones, which complicates historical comparisons. Copernicus has adopted a new index that accounts for the warming of tropical oceans, and by that measure the current event is not yet stronger than past ones. Even so, it said September's values point to an "already exceptionally strong El Niño", especially as the peak has not yet arrived. Not all forecasters use the same scale.
The broader picture is also one of record heat. Global average sea surface temperature hit a record 21.05C for September, topping the 20.92C recorded in September 2023. The world had its second-hottest September on record, with surface air temperatures averaging 16.27C, or 1.63C above the pre-industrial average of 1850-1900.
This matters because of the 2015 Paris Agreement, in which nations pledged to keep warming well below 2C and to pursue efforts to limit it to 1.5C. The United Nations declared in September that the long-term 1.5C target would be missed within a few years. Copernicus director Carlo Buontempo said the world is in a new run of months above 1.5C that is likely to last into 2027. "Crossing the Paris Agreement's long-term limit is only a matter of time. How far we overshoot, and for how long, is still up to us," he said. Scientists stress that cutting fossil fuel emissions is crucial to shorten any overshoot and bring temperatures down quickly.
El Niño is the warming phase of a natural climate cycle that heats the central and eastern equatorial Pacific and shifts winds, pressure and rainfall patterns worldwide, raising the risk of drought and flooding. It typically occurs every two to seven years and lasts roughly nine to 12 months. Experts have warned that this event would likely push global temperatures to a new record in 2027.