Super El Nino could cause 3,500 extra U.S. deaths, report warns

The United States could see 3,500 additional heat-related deaths over the next six months as this year’s “super” El Nino pushes global temperatures well above normal, according to a new report from the University of Chicago’s Climate Impact Lab.

The report, titled “451,000 at Risk: Where Action Can Save Lives During the Super El Niño,” projects that global land temperatures will run 2.1 degrees Fahrenheit above normal in the coming months, driving a 44% increase in extremely hot days compared with a typical year. Researchers estimate the resulting heat will contribute to roughly 239,000 excess deaths worldwide between September and February, with the total climbing toward 451,000 when measured from the start of the El Niño event in June.

The U.S. ranks among the top 20 countries for projected heat-related fatalities but falls far behind the hardest-hit nations. Nigeria is projected to see the most excess deaths, at 31,400, followed by Indonesia with 19,300 and Sudan with 17,500. The Sahel region as a whole is expected to see nearly 66,800 additional deaths.

The current El Nino has already broken records and has not yet reached its projected peak, with sea-surface temperatures in the central tropical Pacific running about 5.4 degrees Fahrenheit above average. Forecasters expect the El Nino itself to persist through the Northern Hemisphere spring of 2027, and researchers say its heat effects — including elevated temperatures and heat-related deaths — could continue to linger into June and July even after that.

The report’s authors — led by economist Michael Greenstone — cast the event as a preview of conditions climate change is expected to make routine within a couple of decades. “It’s a postcard from the future,” the report states, adding that near-term mortality projections show “where we are headed if new adaptation investments do not materialize.”

The projections are drawn from statistical modeling that applies established temperature-mortality relationships across more than 24,000 regions worldwide to seasonal temperature forecasts; the authors note that full details of the methodology are still to come, in an upcoming peer-reviewed journal article.

The authors argue that, unlike long-term climate change, this year’s spike gives governments and aid groups a narrow but real window to intervene — through heat warnings, cooling centers, expanded health outreach and other measures the lab’s Adaptation Inventory has found effective. They estimate targeted action could still prevent tens of thousands of deaths before the forecast period ends in February.