Beyond the Limit: The air pollution damages of overshooting temperature

Abstract Outdoor air pollution is responsible for a substantial amount of premature deaths, severe illnesses, and economic damages. In 2019, according to the Global Burden Disease, it caused 4.505 million [3.625-5.364 95% CI] deaths. However, we can expect air pollution co-benefits from climate change mitigation policies in the next decades. Some scenarios revised by the recent IPCC AR6 report follow a new carbon budget design --- the net-zero pathways --- which avoids temperature overshoot. We examine if the net-zero pathways can consistently deliver improved air pollution outcomes. Here, we use a global source-receptor air pollution model to estimate concentrations and the health impacts and economic damages of climate mitigation scenarios. Moreover, we sought to investigate the primary factors contributing to uncertainty in air pollution mortality and damages, as well as how they interact, with particular emphasis on the significance of non-overshooting scenarios. We implement several relative risk functions to compute premature deaths and a set of air pollution damage functions. We conclude that stringent climate policies, keeping well below 2ºC, and net-zero pathways consistently improve the health and economic co-benefits and reduce the risk of extreme mortality outcomes. Improvements are particularly important for China and India. These results are robust across several air pollution damage estimation methods and normative choices. Globally, net-zero policies avoid 211 thousand [133-274 95% CI] premature deaths and 748 billion [724-766 95% CI] USD/2010 of damages relative to end-of-century in 2030.