The 21st Century Climate Response to China's Clean Air Action

China’s clean air action (CAA) has significantly reduced air pollution and human risk, cutting sulfur dioxide emissions and the cooling effect of sulfate aerosol (SO ₄ ) by 90% since 2007. However, the extent to which the CAA and the emission reductions of SO ₂ and other scattering aerosols could affect climate and the country’s carbon targets remains unclear. Here, we examine the individual and combined radiative forcing (RF) of nine climate forcers using an Earth system model and find that the CAA has significantly diminished SO ₄ cooling by a factor of about six in 2020 compared to a counterfactual scenario without the CAA, resulting in a temperature increase of 0.08°C over the past thirty years. A shift from negative to positive RF, indicating a transition from cooling to warming trends, occurred in 2007. In the absence of the CAA, this shift would have been postponed by six years to 2013. We estimate an adjusted CO ₂ emission derived from CO ₂ and SO ₄ radiative forcing, which indicates that, amid the trade-off between climate warming and emission mitigation, China’s CAA will delay its carbon peak by eight to thirteen years, and the weakening of SO ₄ cooling effects enhances its contribution to global warming by nearly six times. However, if the reductions of other climate forcers are included, their combined warming effect diminishes significantly.