Reconstructing mortality burden from temperature extremes using age-specific mortality rates over 130 years in the city of Madrid, Spain

Understanding how extreme temperatures impact mortality across population groups is critical for assessing vulnerability to climate change and designing effective public health interventions. This study builds on previous work analyzing temperature-attributable mortality fractions in Madrid from 1890 to 2019 by converting these into age-specific mortality rates. Using daily temperature and all-cause mortality data, combined with annual population estimates by age group, we estimated time series of  temperature-specific mortality rates to capture long term and period changes in mortality through time. These were analyzed over time to assess changes in risk exposure and adaptation patterns. We applied generalized linear models to investigate long-term trends in heat- and cold-attributable mortality rates, accounting for demographic shifts, population aging, and historical public health interventions, including the introduction of heat prevention plans in the mid-2000s. The results show that while the overall mortality rate in Madrid declined substantially over the study period, temperature-specific mortality rates decreased even more sharply. Cold-related mortality showed the strongest declines, while heat-related mortality reductions were more modest. These trends varied by age group and time period, with older adults consistently exhibiting higher vulnerability. By linking historical mortality surveillance with temperature exposure and population data, this study offers a rare long-term perspective on how age-specific vulnerability to temperature extremes has evolved. It contributes methodologically by translating attributable fractions into dynamic mortality rates, enabling direct comparison across time and demographic strata. Our findings underscore the need for sustained climate-health adaptation policies and highlight persistent age-based inequalities.