The lack of progress in addressing climate change has led to increased interest in solar radiation modification (SRM)—a collection of large-scale interventions that cool the planet by managing the amount of solar radiation that reaches the earth. SRM complicates climate change governance because, in addition to advancing collective action to reduce greenhouse gas emissions, governance needs to restrain unilateral SRM action while balancing diverging actor interests, ethical risks and scientific uncertainty. We survey international climate policy experts for their assessments of the potential for effective global governance of SRM and the likelihood of possible international responses to unilateral SRM scenarios. Experts are pessimistic about the global community achieving effective SRM governance, and they believe unilateral SRM action will trigger international responses and conflicts. Experts believe softer responses are most likely (e.g., diplomatic sanctions) but the potential for stronger responses, including military action, are non-trivial. Relative to the Global North, experts from the Global South are relatively more supportive of SRM, including the development of SRM, the inclusion of SRM in international negotiations, and the deployment of SRM in a climate emergency.