Record El Niño could cause more than 450,000 extra heat deaths by February, researchers estimate

The El Niño now warming the planet is projected to cause more than 450,000 additional heat deaths worldwide between June 2026 and February 2027, according to estimates released by a team of climate researchers.

The deaths would come on top of those already driven by rising temperatures from climate change, the researchers said. The hardest-hit countries over the next six months are projected to be Nigeria, Indonesia, Sudan, India and Brazil, with Africa's Sahel region and Southeast Asia also heavily affected. The United States ranks among the 20 most affected countries, with about 3,500 projected extra deaths.

“The estimate of 451,000 people is such a large number that it can be numbing, but it is made up of parents and children, grandparents and neighbours, people going to work, caring for families, and living their lives,” said Michael Greenstone, co-founder of the Climate Impact Lab at the University of Chicago and a co-author of the report.

The team modeled the month-by-month link between temperature and excess deaths in 24,378 regions and combined it with El Niño temperature forecasts. Because the estimates are regional, the authors said governments can use them to target heat warnings, cooling centers, extra hospital staffing and protections for outdoor workers. The report has not yet been peer reviewed, but Greenstone said it “would have been irresponsible to sit on it.”

The current El Niño set a record Sept. 21 for the highest temperature ever measured for the phenomenon, months before its expected peak. Excess heat deaths are expected to stay elevated until mid-2027.

This brief is based on reporting by Damian Carrington, published Sept. 23, 2026, in The Guardian. Read the original: https://www.theguardian.com/environment/2026/sep/23/el-nino-450000-extra-deaths-six-months