Efficient nitrogen management as a win-win strategy for air quality, health, and climate

Abstract

Reactive nitrogen (Nr) management links climate policy, air quality and food production, yet its combined impacts remain poorly quantified. Here, we conduct ensemble simulations with two global climate models, Goddard Institute for Space Studies (GISS) and Community Earth System Model (CESM), to evaluate the air quality and climate co-benefits of Nr mitigation. By mid-century, both models simulate positive aerosol radiative forcing (RF) and negative ozone RF, yielding a net positive RF of 150 mW m − 2 (95% CI: 120–180 mW m −2 ) in GISS and 60 mW m −2 (10–120 mW m −2 ) in CESM. Global air quality also improves, with global area-weighted mean PM 2.5 concentrations decreasing by 0.16 µg m −3 (0.07–0.25 µg m −3 ) and 0.13 µg m −3 (0.05 to 0.21 µg m −3 ) and global area-weighted mean maximum daily 8-h average ozone decreasing by 1.69 ppb (1.48–1.89 ppb) and 0.99 ppb (0.88–1.10 ppb) in GISS and CESM, respectively. Regional PM 2.5 reductions exceed 5 µg m −3 . Moreover, more than 80% of avoided premature deaths occur across 0–60°N. Although efficient nitrogen management induces a modest, transient near-term climate penalty, long-term climate benefits from lower N 2 O emissions eventually offset this effect and deliver major air quality, health, and ecosystem co-benefits.