Valuing Wildfire Smoke Related Mortality Benefits from Climate Mitigation

Human-induced climate change has increased wildfire risks, associated air pollution, and health damages in North America. Despite its large potential for damage, climate-induced wildfire smoke is rarely incorporated in estimates of the societal costs of climate change. We develop an integrated framework to estimate PM₂.₅ from climate-induced wildfire smoke and the associated mortality damage in the U.S. Our framework combines econometric estimates of smoke-mortality relationships, machine learning estimates of climate-smoke relationships, and econometric estimates of negative feedbacks between current and future wildfire activity. We estimate that 3°C of future warming will lead to 46,200 annual deaths associated with smoke pollution in the US, doubling estimated mortality from smoke during 2011-2020. For an additional tonne of CO₂ emitted in 2025, we estimate a partial social cost of carbon of $15.1 (95%CI: $2.5-$49.3) due to climate-induced wildfire smoke mortality in the U.S, which doubles current estimates of the U.S. domestic social cost of carbon. We estimate that smoke-related mortality benefits due to projected emissions reductions from the 2022 Inflation Reduction Act are alone equal to 25% of estimated abatement costs associated with the Act.