Super El Niño heat could cause 451,000 excess deaths by February 2027, study finds

Global mortality projections

Extreme heat driven by an intensified El Niño weather pattern could cause up to 451,000 excess deaths worldwide between June 2026 and February 2027, according to a study by the Climate Impact Lab. The research consortium, comprising economists and climate scientists from the University of Chicago and the University of California at Berkeley, evaluated temperature and mortality relationships across 24,378 distinct geographic regions. Their projections compare anticipated heat fatalities against historical mortality baselines from 1996 to 2025. The study projects a 44% increase in the frequency of extremely hot days worldwide relative to normal years. The authors describe the phenomenon as a postcard from the future, delivering temperature conditions that will become typical in several decades.

Regional disparities and vulnerable populations

The mortality projections show that developing countries will bear the primary burden of excess heat fatalities. Africa's Sahel region faces an estimated 66,800 additional deaths, with Nigeria accounting for the largest single-country projection at 31,400 fatalities. Indonesia ranks second globally with 19,300 projected heat deaths, followed by Sudan at 17,600. Across Southeast Asia, the combined projected death toll for the Philippines, Vietnam, Thailand, and Cambodia reaches 19,400. In South Asia, India is projected to experience 15,800 excess deaths, while Brazil leads South American projections with 13,300 fatalities. The United States ranks among the 20 most affected countries, with 3,500 projected additional deaths. Michael Greenstone of the University of Chicago explained that heat vulnerability concentrates in poorer, naturally hotter locations with limited cooling infrastructure.

If you're already in a hot place, the extra couple of degrees are going to be much more dangerous.

Ocean warming and temperature projections

The current El Niño developed in June 2026 and has elevated sea-surface temperatures in the central equatorial Pacific by 3 degrees Celsius (5.4 degrees Fahrenheit) above average baselines. The atmospheric release of oceanic heat is projected to push global land temperatures 1.2 degrees Celsius (2.1 degrees Fahrenheit) above normal levels. In early September, the United Nations weather agency projected a 100% probability that El Niño conditions will persist through February 2027. Climate scientists caution that mortality effects may extend beyond the six-month study window, with secondary heat risks persisting into June or July 2027. These thermal impacts compound ongoing vulnerabilities from droughts, wildfires, and reduced water supplies.

Adaptation recommendations and public health response

The report, titled "451,000 at Risk: Where Action Can Save Lives During the Super El Nino", outlines an adaptation inventory designed to reduce preventable fatalities. Recommended public health interventions include opening public cooling centers, deploying heat warning systems, establishing drinking water stations, and mandating workplace protections for outdoor laborers. The authors also advise hospitals and medical facilities to increase staffing levels during peak temperature periods and provide targeted support for elderly populations. Public health experts note that while many governments possess emergency frameworks on paper, execution and funding remain persistent constraints. Abhiyant Tiwari of NRDC India emphasized the need for operational measures during severe heatwaves.

The real measure of our preparedness is not how many heat warnings we issue, but how effectively we protect people and reduce preventable deaths.