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Study Links Very Strong El Niño to Higher Heat Mortality

lite News Desk 2 min read

Years with very strong El Niño conditions are associated with an estimated 28.87% rise in heat-related deaths worldwide, according to a study in Nature Medicine. The estimate represents 107,035 additional deaths annually, with a reported 95% estimated interval ranging from 27,336 to 176,312. The findings describe an epidemiological association, not proof that El Niño was the sole cause of those deaths.

For cold-related deaths, the study puts the global reduction in very strong El Niño years at 3.70%, equivalent to 112,681 fewer deaths a year. Its 95% estimated interval spans 22,203 to 207,619 fewer deaths. The abstract does not establish a precise total for the combined heat-and-cold burden; it says the point estimates suggest that burden shifts toward countries with lower Human Development Index (HDI) levels and away from those with high HDI levels.

The distribution of the estimated heat-related increase differed across HDI groups. Countries in the low and medium categories together represented 67.65% of the global increase calculated for very strong El Niño years. The medium-HDI group had the largest estimated increase: 61,863 additional deaths per year, with a reported 95% estimated interval of 19,939 to 105,888.

Nature Medicine published the research by Natalia Shartova and co-authors online on 4 November 2026. According to the study, the analysis brought together worldwide databases covering temperatures and deaths, alongside epidemiological models, to estimate how temperature-related mortality was associated with variation in ENSO and its intensity.

ENSO involves changes in both ocean temperatures and the atmosphere above them, according to the World Health Organization. The ocean-temperature changes occur in the equatorial Pacific’s central and eastern regions. WHO identifies El Niño and La Niña as ENSO’s oceanic phases, while the atmospheric component is known as the Southern Oscillation. As general background on the climate pattern, WHO says its effects differ by region depending on an event’s strength, how long it lasts and when it occurs.

* This article is based on publicly available information at the time of writing.

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