Robust Solar Radiation Modification Strategy for Achieving Temperature Targets

Solar radiation modification (SRM) provides an additional cooling option for limiting warming, but uncertainties about its realized cooling outcomes challenge the robustness of temperature-target strategies. This study develops an SRM decision framework that is robust in achieving the temperature target by embedding the min-max regret (MMR) rule into an integrated assessment model. We evaluate SRM strategies under uncertainty in cooling efficiency, SRM-related damages, and climate sensitivity. The results show that policies designed for adverse cooling-response states can better avoid temperature-target failure but generate great welfare losses from over-deployment. The MMR-based strategy exhibits distinct phasing, with restrained deployment before mid-century and accelerated deployment thereafter. Sensitivity analyses show that this two-phase pattern remains robust across alternative uncertainty sets. Overall, the robust framework balances the risk of temperature-target failure against the welfare cost of over-deployment under persistent uncertainties.