Pacific warming surge ties historic El Niño peak, scientists warn
Sea surface temperatures in the tropical Pacific have matched the previous daily record for the El Niño index, reaching 3.07°C above the baseline as of 19 September. The event, underway since June, has developed faster than any prior El Niño on record and is expected to keep intensifying, as strong events typically peak in winter. Researchers note the current anomaly is already statistically tied with the 2015 record, with some using different baselines declaring a new high.
The Niño 3.4 anomaly measures sea surface warmth in the central Pacific against a 30-year baseline. At 3.07°C, it statistically ties the 2015 record, though some researchers using a different baseline already declare a new high. This event, active since June, has developed faster than any prior one, outpacing the 1997 and 2015 events at the same seasonal point.
El Niño strength is classified from weak (0.5°C) to very strong (2.0°C), with the current anomaly far exceeding that threshold. A separate metric, RONI, subtracts broader tropical ocean warming to isolate natural variability, which can reduce the apparent intensity of strong events. Historical data shows strong events typically continue intensifying after mid-September, with peaks usually occurring in November or December.
This record-tying El Niño could amplify extreme weather globally, potentially intensifying droughts, floods, and heatwaves in vulnerable regions. It may also temporarily elevate global average temperatures, compounding long-term warming pressures. Communities reliant on agriculture, water resources, and disaster preparedness could face heightened stress, while economic sectors like insurance and shipping might see increased volatility. The rapid development suggests less lead time for adaptation, though impacts will vary regionally.