This year’s powerful El Niño and the record global heat it’s driving, along with severe droughts, wildfires and shrinking water supplies, could lead to nearly half a million more deaths worldwide by the end of February, according to a research report released Wednesday (September 23, 2026).
El Niño is a natural climate pattern, but this year’s unusually strong event is occurring on a planet already warmed by human-caused climate change, increasing the risks from extreme heat. The study combined seasonal temperature forecasts with localised estimates of how high temperatures affect mortality across more than 24,000 regions worldwide.
The research, he said, shows that heat is most dangerous in places that are already hot and relatively poor. Abhiyant Tiwari, a heat expert at NRDC India who was not involved in the study, said the report’s projections should serve as a call to action rather than be another reason for alarm.
The grim warning by the University of Chicago-based Climate Impact Lab says that as many as 451,000 more heat-related deaths between June and the end of February could be attributed to El Niño, compared with heat deaths expected in a typical year. The fallout of the weather phenomenon could be felt well into next summer, he added. The study by Greenstone and his colleagues also warns that the Global South — a term that isn’t geographical but a reference to developing countries in general — will bear the heaviest burden of the excessive heat.
Michael Greenstone, a co-founder of the group and the study’s co-author, said the heat danger will likely persist beyond February — even though this El Niño is expected to end by then.
