A bottom-up social cost of carbon for Latin America: Municipality-level heat-mortality damage functions from 30 million daily death records

Temperature–mortality response functions have been quantified across many climate zones, but for most of the developing world they have not been translated into country-specific economic damages at sub-national resolution. This study estimates bottom-up mortality social costs of carbon (SCC) for five Latin American countries at municipality resolution. We assemble 30 million daily death records across 10,214 municipality-equivalent units in Brazil, Mexico, Chile, Ecuador and Peru (2000–2023) and merge them with the ARCO-ERA5 reanalysis sampled at every unit centroid. Country-specific Poisson exposure–response functions, estimated separately by country with municipality, year, month and day-of-week fixed effects, recover same-day heat-mortality semi-elasticities of 10.9% (Brazil) and 13.0% (Mexico) at a daily maximum temperature of 35 °C or above, relative to a 20–25 °C reference. Translating these functions along the SSP2-4.5 warming path, with the transient climate response to cumulative emissions, an income-driven attenuation of the response, a value-of-statistical-life path that rises with projected income, and population ageing, yields central mortality SCCs of about USD 0.5/tCO₂ in Brazil and USD 0.3/tCO₂ in Mexico at a 2% discount rate, with a small negative value for cool-climate Chile and near-zero values for Ecuador and Peru. These bottom-up, mortality-only estimates are a fraction of full-system country-level SCCs but share their cross-country ordering and signs, and the underlying damage functions imply a substantial annual heat-mortality burden that the sparse regional evidence in global assessments does not capture.