Super El Niño brings new mortality forecast
A model study estimates that extreme heat could cause up to 451,000 additional deaths worldwide between June 2026 and February 2027.
Researchers at the Climate Impact Lab estimate that the current strong El Niño could cause up to 451,000 additional heat-related deaths worldwide over nine months. This is a model forecast compared with a normal year, not a fixed future death toll.
The estimate appears in a report by the Climate Impact Lab, a research collaboration centred on the University of Chicago. The researchers compare the expected heat during the current El Niño with average conditions in the same months from 1996 to 2025 inclusive. The report covers the period from June 2026 through February 2027.
Some initial headlines omit an important distinction: 451,000 is the total for nine months. For the six months from September 2026 through February 2027, the report arrives at 239,000 additional deaths, with an uncertainty margin of approximately 11,000. In both cases, these are modelled deviations from an average year.
The researchers expect global land temperatures to average 1.2 degrees Celsius above normal in the coming months. According to their calculations, this would mean 44 per cent more extremely hot days than usual. The largest numbers are expected in parts of the Sahel, South-East Asia, India and Brazil.
The calculation uses relationships between temperature and mortality from 24,378 regions. These are linked to seasonal forecasts from the European weather model ECMWF. The researchers have incorporated uncertainties from both the weather forecast and the mortality models used. The methodological details have yet to be published in a peer-reviewed journal.
The figures are therefore neither a measurement of deaths that have already occurred nor a prediction made with certainty. They provide a risk estimate based on the current weather forecast. In addition, the researchers count only additional deaths caused by heat; possible consequences of drought, flooding, wildfires, food shortages or disease fall outside this specific calculation.
The report names heat warnings, cooling centres, additional healthcare capacity, water points and protection for outdoor workers as measures that could reduce risks. The choice of such measures is political and administrative: the study does not say which government should spend how much money. It does, however, show where the model identifies the greatest acute vulnerability.
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The figures are correctly presented as model forecasts rather than certain mortality figures. The text corrects the common confusion between the nine-month estimate of 451,000 and the six-month estimate of 239,000.
- confirmed The report projects 451,000 additional heat-related deaths between June 2026 and February 2027. — This is stated in the Climate Impact Lab report. source
- confirmed For September 2026 through February 2027, the estimate is 239,000 plus or minus 11,000. — The report provides this separate six-month estimate. source
- confirmed The calculation uses 24,378 regions and ECMWF seasonal forecasts. — The report’s methods section describes this approach. source
- confirmed The methodological details have yet to appear in a peer-reviewed journal. — The report states that full details will be published in a future peer-reviewed journal. source
Editor's note
The mortality figures are model outputs from a new report and not yet a peer-reviewed publication. The periods, uncertainty margin and methodological limitations are explicitly stated; the mortality forecast may be adjusted as El Niño develops further.Sources
- 451,000 at Risk: Where Action Can Save Lives During the Super El Niño — Climate Impact Lab
- More than 451,000 Heat Deaths Projected from Super El Niño — University of Chicago Institute for Climate and Sustainable Growth
- September 2026 Quick Look — International Research Institute for Climate and Society
More on this in Dutch media
- NU.nl — „el niño”
- De Telegraaf — „el niño”
- Trouw — „el niño”