Synergistic reductions of CO2 and aerosols: Navigating mid-term warming risks for 2 °C climate futures

Achieving the 2 °C climate target requires the coordination of strategies for greenhouse gases (GHGs) and air pollutants mitigation, yet their complex interactions remain insufficiently explored. BCC-ESM1 Earth system model is employed to compare global climate responses under the novel SSP2-com scenario, in which both GHGs and aerosols undergo reduction, with that under the SSP2-4.5 scenario. Moreover, the relative contributions of carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), and black carbon (BC) to future temperature increases are analyzed. Results reveal that compared with the SSP2-4.5 scenario, the SSP2-com scenario can stabilize the end-21st-century temperature rise well below 2 °C, primarily driven by the reduction of anthropogenic CO 2 emissions. A mid-term warming rebound between 2061 and 2080 is observed due to reduced aerosol cooling. SO 2 reductions result in a weakening aerosol-induced radiative forcing, driving regional warming asymmetries—particularly in northern high latitudes (up to +1.5 °C in winter). Compared to CO 2 -only mitigation, experiments involving SO 2 reductions also exhibit stronger global precipitation increases, suggesting an acceleration of the hydrological cycle under lower aerosol loading. Energy budget analysis further indicates that SO 2 mitigation results in an increase in net shortwave radiation at the top of the atmosphere by approximately 0.23 W/m 2 during the mid-term (2061–2080), and consequently leads to an accumulated surface energy gain of about 0.15 W/m 2 . These findings highlight a key trade-off: aerosol mitigation may induce mid-term warming, but remains essential for achieving air quality and climate goals. This work underscores the necessity of balancing mid-term climate–air quality trade-offs with long-term decarbonization, offering actionable insights for policymakers to design integrated pathways align with the Paris Agreement.