Model study: Earlier net zero limits El Niño-like shift in the Pacific
Even after emissions stop, the tropical Pacific stays altered for centuries, Melbourne-led simulations show. But stopping sooner limits extreme El Niño events.
Symbolic image · Photo: NASA / Wikimedia Commons, Public domain (cropped and resized)
Global warming pushes the tropical Pacific toward a more El Niño-like average state, and reaching net zero emissions will not quickly reverse it, according to a modeling study led by the University of Melbourne with partners including the Australian National University, the University of Reading and Australia's CSIRO science agency. It was published Oct. 13 in Communications Earth & Environment (DOI: 10.1038/s43247-026-04082-x). The usual temperature difference between the warmer western and cooler eastern Pacific weakens, though the authors stress this is not a permanent El Niño.
The researchers analyzed nine Earth system models in which emissions stop at about 2 degrees Celsius of warming and ran Australia's ACCESS model for 1,000 years after emissions end in 2030, 2045 or 2060. Because the Southern Ocean and deep ocean keep warming, the altered state persists for centuries; in eight of nine models the gradient keeps weakening. In ACCESS, the share of extreme El Niño events rises from 1.7% in pre-industrial times to 26.3% if emissions stop in 2060, compared with 16.4% for a 2030 stop. Changes in El Niño strength, however, depend heavily on the model.
"We found clear benefits from reducing emissions quickly," said co-author Andrew King, an associate professor at the University of Melbourne. Reaching net zero earlier reduces the risk of leaving future generations a substantially altered tropical Pacific, he said. The study describes projections, not measurements. It comes as a real El Niño strengthens: the World Meteorological Organization expects it to peak in December and says it could be one of the strongest since at least 1950, according to an Oct. 8 statement.