September 27, 2026 | Environment & Climate
A rapidly strengthening Super El Niño could expose millions of people to unusually high temperatures and contribute to an estimated 451,000 additional heat-related deaths globally between June 2026 and February 2027, according to a new projection by the Climate Impact Lab, a research initiative associated with the University of Chicago's Energy Policy Institute.
The figure represents modelled excess deaths compared with what would be expected during a normal year; it is not an observed death toll or a definitive prediction of deaths that will occur.
The Climate Impact Lab estimates that approximately 239,000 of the projected excess deaths could occur between September 2026 and February 2027, the six-month period covered by its current seasonal forecast. The researchers estimate that global land temperatures during the period could average around 1.2°C above normal, with approximately 44 percent more extremely hot days than would normally be expected.
The researchers describe the event as a possible “postcard from the future”, because the projected temperatures resemble conditions that climate change could otherwise produce roughly two decades from now. The comparison is intended to illustrate the increasing importance of adaptation and preparedness as warming pushes extreme heat into conditions communities may not yet be adequately prepared to withstand.
How were the 451,000 deaths estimated?
Emily Grover-Kopec, a co-author of the report, has clarified that the estimate was produced by combining seasonal temperature forecasts with established temperature-mortality relationships.
According to Grover-Kopec, the Climate Impact Lab has developed temperature-mortality relationships for 24,378 regions worldwide, accounting for differences in local climate, vulnerability and adaptive capacity. Those relationships were then applied to seasonal temperature forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF).
Grover-Kopec said the ECMWF seasonal forecast was selected because, among a range of available seasonal forecasts, it sits roughly in the middle of projected temperature anomalies and therefore provides a relatively moderate scenario rather than an extreme upper-end forecast.
The temperature-mortality relationships used in the analysis are based on peer-reviewed research published in the Quarterly Journal of Economics in 2022. However, the specific application of that methodology to the current short-term Super El Niño forecast has not yet undergone peer review. Researchers say the methodology will be published separately.
The projections are measured against the 1996-2025 period, a recent 30-year climate baseline. Grover-Kopec explained that using the most recent 30-year period was intended to make the estimates relevant to present-day planning, including decisions about where and when resources should be deployed to protect people from extreme heat.
India could see 15,800 additional heat-related deaths
India is among the countries projected to experience a substantial increase in heat-related mortality.
The Climate Impact Lab estimates approximately 15,800 additional heat-related deaths in India between September 2026 and February 2027, compared with a normal year. About 7,400 of those deaths are projected for December 2026 through February 2027.
Grover-Kopec explained that the seasonal pattern is important. Northern India normally experiences relatively cool winters, meaning heat contributes less to winter mortality. Southern India, however, remains sufficiently warm during winter for heat-related mortality to occur, so additional warming can produce a larger increase in deaths.
The researchers also warn that India's heat-related mortality could continue increasing beyond the current six-month forecast period and into the country's next summer if unusually warm conditions persist.
Other regions are also projected to face significant impacts. The Climate Impact Lab estimates approximately 66,800 additional heat-related deaths across the Sahel, including about 31,400 in Nigeria; 19,300 in Indonesia; 19,400 across the Philippines, Vietnam, Thailand and Cambodia; and approximately 13,300 in Brazil during the six-month forecast period.
Extreme heat is only part of the risk
The projected 451,000 deaths concern heat-related mortality only. They do not represent the total potential human impact of the current El Niño.
The researchers note that unusually high temperatures and changing rainfall patterns can also increase risks from drought, wildfire and flooding. Deaths associated with those hazards are not included in the 451,000 estimate.
This distinction is particularly important for countries across South Asia and the wider Himalayan region, where communities are simultaneously confronting extreme heat, erratic rainfall, floods, landslides, drought and other climate-related hazards.
A warning that can still be acted upon
Despite the uncertainty surrounding any modelled mortality projection, the report's central message is that seasonal forecasting creates an opportunity for preventive action before extreme heat occurs.
The Climate Impact Lab points to measures including early-warning systems, cooling centres, hydration facilities, stronger health-system preparedness, heat-health action plans and protections for outdoor workers.
Indian climate and public-health experts have similarly described the projection as a potentially useful early warning while cautioning that the mortality numbers should be interpreted as model-based estimates rather than definitive forecasts.
For vulnerable countries, the significance of the report therefore extends beyond the headline number.
The projection demonstrates how advances in seasonal forecasting and temperature-mortality research may increasingly allow governments and humanitarian organisations to identify populations at elevated risk months before extreme heat occurs.
For countries already experiencing accelerating climate hazards, that lead time could be critical for protecting vulnerable people-including older adults, children, pregnant women, people with underlying health vulnerabilities and outdoor workers-from potentially dangerous heat exposure.
The Climate Impact Lab says it will continue updating its estimates as El Niño develops and additional forecasting information becomes available.
Ecosphere News will continue monitoring the evolving El Niño situation and its implications for South Asia, the Himalayas and vulnerable communities worldwide.
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