Super El Niño heat waves could cause 451,000 deaths worldwide with Brazil among most vulnerable nations
Excess heat driven by the current Super El Niño could cause 451,000 deaths worldwide between June 2026 and February 2027, according to an assessment by the Climate Impact Lab at the University of Chicago released on Wednesday (23). Brazil ranks among the five most vulnerable countries to the thermal spike, with an estimated 13,271 additional heat-related fatalities during the nine-month period.
Projections indicate that 239,000 of those deaths are concentrated in the six months between September 2026 and February 2027 as global temperatures intensify. “The estimate of 451,000 people is such a large number that it can numb, but it is made up of parents and children, grandparents and neighbors, people going to work, taking care of their families and living their lives,” said Michael Greenstone, co-founder of the Climate Impact Lab and professor of economics at the University of Chicago.
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Which countries face the highest death toll?
The research shows that thermal mortality falls disproportionately on developing nations across tropical and equatorial belts, including 66,800 deaths projected solely within the African Sahel. The highest totals are concentrated in five countries:
Global health agencies warn of cascading humanitarian risks
During a joint briefing in Geneva on Tuesday (22), the World Health Organization and the World Meteorological Organization alerted that the intensifying climate event elevates compounding public health hazards well beyond thermal stress alone. Officials reported that El Niño disrupts regular weather patterns, accelerating drought and crop failures among the 150 million people already facing acute food insecurity worldwide, while simultaneously increasing outbreaks of waterborne cholera and mosquito-transmitted infections including dengue, malaria, yellow fever, chikungunya, and zika. Teresa Zakaria, head of the WHO Risk Reduction, Humanitarian Operations and Climate Change Unit, stated that the phenomenon “is a risk multiplier, and we expect to see health impacts around the world.”
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- Nigeria: 31,400 projected excess deaths
- Indonesia: 19,300 projected excess deaths
- Sudan: 17,400 projected excess deaths
- India: between 15,600 and 15,800 projected excess deaths
- Brazil: 13,271 projected excess deaths
Peak ocean warming coincides with southern summer
The present El Niño began in June 2026 and broke Pacific Ocean surface temperature records before reaching its typical peak cycle, simulating average global thermal levels that atmospheric models previously anticipated only decades from now. Theodore Keeping, a climate scientist and research associate at Imperial College London, explained that shifts in regional patterns dictate whether populations experience severe inundations or dangerous heat stress, with models projecting a 44% increase in scorching heat days compared to a typical year. The climatic anomaly is expected to reach its highest intensity around Tuesday, December 1, 2026, compounding the natural heat of the Southern Hemisphere summer through early 2027.
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Uncertainty remains for heat impacts beyond February 2027
The quantitative mortality projections conclude on Sunday, February 28, 2027, because seasonal forecast models cannot reliably compute mortality metrics further in advance. Researchers at the Climate Impact Lab note that elevated temperatures and associated health risks will persist across multiple regions until mid-2027, when newer climate modeling will allow scientists to assess the full toll of the phenomenon.
