Governing atmospheric oxidation capacity is the key to synergistic air quality and climate gains

Z. Tan, X. Ma, K. Lu, X. Li, Q. Zhu, F. Rohrer, A. Novelli, H. Fuchs, A. Wahner, L. Whalley, D. Heard, S. Brown, X. Zhang, Y. Zhang

Abstract

Effective management of air quality and climate change requires recognition of their fundamental coupling through atmospheric oxidation capacity (AOC), which governs the atmosphere’s self-cleansing capacity. However, policies often overlook the nonlinear chemical feedbacks inherent to AOC, leading to fragmented strategies that risk unintended consequences. Here, we demonstrate that uncoordinated strategies, such as reducing fossil fuel-related NO_X without concurrent methane controls, can suppress OH radicals, inadvertently prolonging methane’s lifetime. This “chemical lockdown paradox,” observed during COVID-19 lockdowns, reveals critical trade-offs, where short-term air-quality gains may increase methane accumulation, offsetting the climate benefits of CO₂ abatement. Given AOC’s spatial heterogeneity, such effects can extend beyond local scales. We thus propose a regulatory framework integrating AOC dynamics through coordinated multi-pollutant controls, advanced multi-scale AOC monitoring, and improved Earth system models with fully coupled chemical feedbacks. This framework paves a science-based pathway for synergistically managing air quality and climate mitigation throughout the decarbonization transition.