Global temperature-related mortality associated with El-Nino Southern Oscillation

El Niño-Southern Oscillation (ENSO) influences the global climate through interconnected atmospheric processes, yet its impact on global and regional temperature-related mortality burden remains unquantified. Here, we integrate global temperature and mortality databases with epidemiological models to assess temperature-related mortality associated with ENSO variability and intensity. During very strong El Niño years, the large amounts of heat released into the atmosphere are associated with an increase in global heat-related mortality of +28.87% (+107,035 annual deaths; 95% eCI: 27,336 to 176,312), and a decrease in global cold-related mortality of -3.70% (-112,681 annual deaths; 95% eCI: -207,619 to -22,203). Increase in heat-related mortality was concentrated in low and medium HDI countries, which accounted for 67.65% of the global increase, with the largest increase in medium HDI countries (+61,863 annual deaths; 95% eCI: 19,939 to 105,888), while point estimates of the combined heat and cold burden suggest a shift of the total burden from high toward lower HDI countries. In a context of continuously warming temperatures, our results indicate that forthcoming El Niño events have the potential to represent new public health challenges, underscoring the need for climate-informed preparedness actions.