More than 450,000 people are expected to die from the additional heat brought by the super El Niño by February, according to estimates by climate scientists. This toll comes on top of the premature deaths already caused by temperatures that have risen because of the climate crisis and will affect regions from Indonesia and India to Nigeria and the United States.
The estimates of heat deaths were made at regional level and, the researchers say, show where protective measures could be implemented to save lives. These include better heatwave forecasts, cooling centres where people can take refuge, increased staffing at medical facilities during the hottest hours and protection for outdoor workers.
The current El Niño, which warms the planet, broke the highest temperature record ever recorded for the phenomenon on Monday, several months before its expected peak. The heat is so much greater than in previous episodes that scientists described it as “staggering” and “Godzilla-level”. El Niños are natural climate phenomena, but they may be intensified by global warming.
The countries expected to be hit hardest over the next six months are the tropical nations of Nigeria, Indonesia, Sudan, India and Brazil. The United States is among the 20 most affected countries, with 3,500 additional heat deaths projected. More broadly, Africa's Sahel and southeast Asia are severely affected.
Professor Michael Greenstone, co-founder of the Climate Impact Lab and a co-author of the report, stressed that the figure of 451,000 people may be numbing, but it is made up of parents and children, grandparents and neighbours, people who go to work, care for families and live their lives.
The death estimate covers the period from June 2026 to February 2027, when the current temperature forecasts end, although elevated levels of heat deaths are expected to continue until June or July 2027. The projections were based on peer-reviewed methods that track the monthly relationship between temperature and additional heat deaths in 24,378 regions worldwide. These were combined with forecasts of higher temperatures due to El Niño over the coming months, using the average number of heat deaths in an average month from 1996 to 2025 as a baseline.
El Niño is also described as a “postcard from our future” because it raises temperatures to the level the climate crisis is expected to bring in 20 years. Dr Tamma Carleton, a co-author, noted that stepping up emergency responses and better targeting efforts can save many lives this year, but warned that in 20 years, when today's extreme temperatures become the new norm, we do not want to be in a permanent state of emergency.
The effects will not be limited to heat. The World Food Programme warned in August that the consequences of El Niño are likely to push around 50 million people into acute hunger and drive up food prices. A major El Niño in 1877–1878 led to more than 50 million deaths from drought and famine, with India, Brazil and China severely affected.
Professor Friederike Otto of Imperial College London explained that the current event is a massive redistribution of energy within the climate system and is dangerous because it is unfolding on top of a much warmer climate system affected by human activity. In many parts of the world, she said, we will see extreme heat events that have never been experienced before, with all the consequences for health, food security and water stress.
Greenstone added that until now people could predict shocks to crops and provide early warnings, but the new report opens the way to doing the same for an even more important outcome: death. The report will be submitted to a peer-reviewed scientific journal, but Greenstone said that, given the urgency of the situation, “it would be irresponsible to keep it under wraps”.
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