Co-benefits of Global Greenhouse Gas Mitigation for Future Air Quality and Human Health

Abstract

Actions to reduce greenhouse gas (GHG) emissions often reduce co-emitted air pollutants, bringing co-benefits for air quality and human health. Past studies ^{1– 6} typically evaluated near-term and local co-benefits, neglecting the long-range transport of air pollutants ^{7– 9} , long-term demographic changes, and the influence of climate change on air quality ^{10– 12} . Here we simulate the co-benefits of global GHG reductions on air quality and human health using a global atmospheric model and consistent future scenarios, via two mechanisms: a) reducing co-emitted air pollutants, and b) slowing climate change and its effect on air quality. We use new relationships between chronic mortality and exposure to fine particulate matter ¹³ and ozone ¹⁴ , global modeling methods ¹⁵ , and new future scenarios ¹⁶ . Relative to a reference scenario, global GHG mitigation avoids 0.5±0.2, 1.3±0.5, and 2.2±0.8 million premature deaths in 2030, 2050, and 2100. Global average marginal co-benefits of avoided mortality are $50–380 (ton CO ₂) ⁻¹, which exceed previous estimates, exceed marginal abatement costs in 2030 and 2050, and are within the low range of costs in 2100. East Asian co-benefits are 10–70 times the marginal cost in 2030. Air quality and health co-benefits, especially as they are mainly local and near-term, provide strong additional motivation for transitioning to a low-carbon future.