El Niño heat may cause 451,000 extra deaths, with India up 15,800

Healthcare systems in already hot, low-resource regions face a quantified near-term mortality shock: Climate Impact Lab warns of 451,000 additional heat-related deaths worldwide through February 2027, with India alone projected at 15,800±1,600. This is not a distant climate scenario—it is a six-month operational and policy challenge. Hospitals, emergency departments, and public health agencies must plan now for surges in heatstroke, dehydration, cardiovascular stress, and other heat-sensitive conditions.

A new report released on Wednesday, September 23, 2026, by the University of Chicago-based Climate Impact Lab projects that 451,000 additional heat-related deaths worldwide could be attributed to the current powerful El Niño between June 2026 and the end of February 2027, compared with heat deaths expected in a typical year. The projection is not a long-range climate scenario but a near-term mortality estimate covering an active, exceptionally strong El Niño event, and it immediately reframes the current heat as a public health emergency rather than a seasonal weather story. The report is designed to give decision-makers location-specific estimates that can drive emergency action, according to Michael Greenstone, co-founder of the Climate Impact Lab and study co-author.

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Healthcare systems in already hot, low-resource regions face a quantified near-term mortality shock: Climate Impact Lab warns of 451,000 additional heat-related deaths worldwide through February 2027, with India alone projected at 15,800±1,600.

The modeling combines seasonal temperature forecasts with localized estimates of how high temperatures affect mortality across more than 24,000 regions worldwide. Researchers estimated additional heat-related deaths by comparing deaths expected under El Niño-driven high temperatures with deaths expected if temperatures remained similar to what they have been over the last three decades. The baseline is the corresponding months from 1996-2025. Earlier in September, forecasts projected a greater than 90% chance of a very strong El Niño during the northern hemisphere autumn and winter, with eastern equatorial Pacific sea surface temperatures already more than 3°C above normal. The term 'Super El Niño' is informal but captures the exceptional strength of the current event.

The geographic distribution is stark. Of the 451,000 additional deaths projected for the entire June 2026 to February 2027 period, 239,000 are projected during the September 2026 through February 2027 window alone. India could see an estimated 15,800 additional heat-related deaths, give or take 1,600, between September 2026 and February 2027, relative to average conditions during the corresponding months from 1996-2025. Indonesia is projected to have 19,300 additional deaths; the Philippines, Vietnam, Thailand, and Cambodia combined are projected at 19,400; Brazil at 13,300; and the Sahel region—a roughly 5,000-kilometre swathe of about ten countries across Africa, including Senegal, the Gambia, and northern Nigeria—is expected to be hardest hit with approximately 66,800 additional deaths. The pattern is that poorer, already hot countries bear the heaviest burden.

The underlying drivers include more than temperature alone. The report highlights severe droughts, wildfires, and shrinking water supplies that accompany the heat. Many of the most exposed places are already struggling with food insecurity and high energy costs, partly due to climate change and the fallout of the war in Iran, according to the report. Greenstone emphasized that heat is most dangerous in places that are already hot and relatively poor. 'If you're already in a hot place, the extra couple of degrees are going to be much more dangerous,' he said. Wealthier places generally have greater access to air conditioning, reliable water supplies, and functioning health systems, which blunt the mortality impact. That means the projected deaths are not inevitable; they are contingent on adaptive capacity, infrastructure, and emergency response.