Study: El Niño Heat Could Kill 451,000 by February

A Climate Impact Lab analysis projects 451,000 extra heat deaths from June 2026 to February 2027 as a super-sized El Niño pushes global land temperatures up 1.2°C.

A new analysis from the Climate Impact Lab, a team of scientists, economists and data engineers headquartered at the University of Chicago, projects that the current El Niño could cause an estimated 451,000 additional heat-related deaths worldwide between June 2026, when the pattern arrived, and February 2027. The projections cover only the first half of the event: El Niño is expected to last until the Northern Hemisphere spring, so researchers believe the number is likely to rise as its heat impacts linger into summer. The deaths would come on top of the usual toll from heat, and from other El Niño-fueled extremes including fires, floods and droughts. Heat is the most deadly form of extreme weather, though heat deaths are poorly tracked even in rich nations. The World Meteorological Organization has warned this El Niño could become the strongest on record.

The report's authors describe the current El Niño as a "postcard from our future": scientists project it will push global land temperatures up 1.2 degrees Celsius (2.1 Fahrenheit) above normal in the coming months, according to Scripps News — exactly the warmth climate change is expected to make normal in about 20 years. The study estimates this will bring 44% more days of extreme heat than a normal year, with the heaviest toll in countries with the fewest resources to adapt. What makes the timing so stark is that this preview is arriving before the world has had time to adapt, the authors write, combining a natural pattern that ramps up global temperatures with the warming already driven by fossil fuel pollution.

The affected regions are overwhelmingly in the Global South. Scripps News reports that Nigeria is expected to see the most El Niño heat deaths, with a projected 31,400 lives lost, and that the United States ranks in the top 20 affected countries with a projected 3,500 deaths. According to Anadolu Ajansı, the Sahel region is projected to record 66,800 additional heat deaths from September through February, Southeast Asia nearly 39,000, India 15,800 and Brazil 13,300. The projections came from combining peer-reviewed methods on the relationship between temperature and mortality across more than 24,000 world regions with seasonal temperature forecasts, and were compared with the same months of an average year between 1996 and 2025.

The report has not yet been peer-reviewed, but the Climate Impact Lab says it uses peer-reviewed methodology and released findings early because El Niño is strengthening so fast. "Given that there is still time now for policymakers and others to take action to prevent these deaths, we felt our findings couldn't wait for the peer review process to play out," a lab spokesperson said, per Scripps News. An outside expert, University of Warwick associate professor Raquel Nunes, called the 451,000 estimate plausible as a modeling exercise but not a definitive prediction. Researchers say tens of thousands of deaths could be prevented through early heat warnings, health action plans, cooling and hydration centers, protections for outdoor workers and expanded healthcare coverage — and they will update the projections as El Niño develops.