Aerosol trends dominate over global warming-induced cloud feedback in driving recent changes in marine low clouds

Over the past two decades, anthropogenic emission reductions and global warming have impacted marine low clouds through aerosol-cloud interactions (ACI) and cloud feedback, yet their quantitative contributions remain unclear. This study employs a deep learning model (CNN _Met−Nd ) and Community Earth System Model version 2 (CESM2) to disentangle these effects. CNN _Met−Nd reveals that aerosol-driven changes in cloud droplet number concentration dominate near-global marine low cloud shortwave radiative effect changes (ΔCRE), contributing 0.42 ± 0.08 Wm⁻² per 20 years, compared to 0.05 ± 0.37 Wm⁻² from cloud feedback. CESM2 effectively reproduces the predominant influence of aerosol reductions on ΔCRE by CNN _Met−Nd , lending us confidence for a stronger estimate of global effective radiative forcing due to ACI (ERF _aci ) of -1.29 Wm⁻² since the preindustrial era. These findings highlight the critical role of ACI in shaping marine low cloud trends and its broader climate implications, especially under ongoing emission reduction efforts.