Abstract
Solar radiation modification (SRM) is increasingly discussed as a policy response to worsening climate impacts and stalled mitigation progress. Yet the viability of SRM hinges on its long-term governance, particularly the risk of abrupt and permanent termination, which could trigger rapid warming and catastrophic outcomes. Here we develop a coupled socio-political–geophysical tipping point (SPTP–GTP) framework to assess the economic conditions under which SRM might reduce rather than amplify global risk. We introduce a novel damage function sensitive to the rate of warming and accounts for both catastrophic and non-catastrophic damages. Using reduced-complexity climate projections and a probabilistic failure modeling, we estimate the expected present value of SRM deployment across a range of governance scenarios. Our findings show that SRM only proves beneficial under a narrow intersection of robust global mitigation, extremely low failure risk, and gradual phase-out. Paradoxically, the same governance failures that make SRM politically attractive undermine the very conditions needed for its safe operation. These findings provide a quantitative, risk–risk perspective on the governance debate, suggesting that the required conditions for SRM are at odds with current socio-political realities.
