Study: Super-sized El Niño could cause more than 450,000 heat deaths by February

Sep 23, 2026 - 22:15

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Nearly half a million people across the world could lose their lives by February due to El Nio-driven extreme heat, according to a sobering new report.

El Nio, a natural climate pattern which typically ramps up global temperature, has now crossed into super-sized territory and is on its way to becoming record-breakingly strong.

Combined with the global warming the planet is already experiencing from fossil fuel pollution, the heat consequences could be devastating, according to the analysis from the Climate Impact Lab, a team of scientists, economists and data engineers headquartered at the University of Chicago, and published Wednesday.

Heat is the most deadly form of extreme weather although heat deaths are not well-tracked, even in rich nations. The report estimates the heat from El Nio could take 451,000 lives between June 2026, when it arrived, and February 2027. Those deaths would be in addition to the usual number of heat-related deaths.

The researchers believe this number is likely to rise El Nino is expected to last until the Northern Hemisphere spring, meaning its heat impacts will linger into the summer months.

The deaths from extreme heat would also come in addition to those expected from other El Nio-fueled extreme weather, including fires, floods and droughts, according to the report.

The report has not yet been peer-reviewed but uses peer-reviewed methodology to reach its conclusions.

We have long been able to predict the impacts of temperatures on crops, and now we can predict their impact on the worst outcome death, said Michael Greenstone, a report author, co-founder of the Climate Impact Lab and an economics professor at the University of Chicago.

This is such a large number that it can be numbing, but it is made up of parents and children, grandparents and neighbors, people going to work, caring for families, and living their lives, he added.

Scientists project that El Nio will push global land temperatures up 1.2 degrees Celsius (2.1 Fahrenheit) above normal in the coming months. This unusual warmth is exactly what climate change is projected to bring in 20 years time, and will lead to 44% more days of extreme heat than would be expected in a normal year, according to the study.

The current El Nio is a postcard from our future thats arriving before the worlds had time to adapt, the authors write.

The regions expected to be most affected are overwhelmingly in the Global South. The report identifies Nigeria as where the most El Nio heat deaths are expected, with a projected 31,400 lives lost. Other countries at high risk include Indonesia, Sudan, India and Brazil. The United States is also in the top 20 affected countries, with a projected 3,500 deaths.

The report combined peer-reviewed methods on the relationship between temperature in more than 24,000 regions across the world and mortality and seasonal temperature forecasts. The death projections were compared to the same months of an average year between 1996 and 2025.

Raquel Nunes, associate professor in health and environment at the University of Warwick in England, who was not involved in the report, said the estimate of 451,000 deaths is plausible as a modeling exercise, but it should not be viewed as a definitive prediction. Its value lies in highlighting the potentially severe consequences of El Nio-driven extreme heat and the urgent need for preparedness.

The study is currently awaiting peer-review, but the scientists said they released the shorter report first due to El Ninos rapid strengthening. Given that there is still time now for policymakers and others to take action to prevent these deaths, we felt our findings couldnt wait for the peer review process to play out. That would certainly be too late to act for this El Nio cycle, said a Climate Impact Lab spokesperson.

Measures countries can take include early heat warnings, health action plans, ensuring cooling and hydration centers are available and expanding healthcare coverage, the report says.

Increasing emergency response and better targeting our efforts can save many lives this year, said report co-author Tamma Carleton, faculty head of research for the Climate Impact Lab and an assistant professor at the University of California, Berkeley. But 20 years from now, once todays extreme temperatures become the new normal, we dont want to be in a constant state of emergency.