Future temperature-related mortality in Latin American cities under climate change and population scenarios

BACKGROUND: In Latin America, climate change, urbanization, and an aging population are intensifying health risks from extreme temperatures. To accurately assess future temperature-related mortality impacts, evidence that integrates key demographic factors-such as the dynamics of population age composition, mortality rates, and population size-is essential. METHODS: We projected the impact of nonoptimal temperatures on all-age and age-specific mortality during 2045-2054 for 326 cities in Latin America. Our analysis combined city-level daily mortality counts, gridded temperature data, downscaled and bias-corrected temperature simulations, and demographic data. We projected temperature-mortality impacts under two climate change scenarios while also considering changing population size, age structure, and age-specific mortality rates. FINDINGS: By 2045-2054, the percentage of heat-attributable deaths under the most extreme temperature scenario will more than double from 0.87 % (95 % CI 0.77, 0.96) to 2.06 % (95% CI 1.80, 2.33), but cold-related mortality will decrease. Population growth and aging will exacerbate heat-related risks and offset reductions in cold-related deaths. For example, changes in population age structure will drive an increase in the heat-related mortality rate of 176% from baseline for a moderate temperature scenario. INTERPRETATION: Beyond temperature changes, demographic shifts-particularly population growth and aging-will significantly amplify mid-century temperature impacts on mortality, underscoring the need for targeted climate adaptation and public health strategies.