Summary
The study evaluates when solar radiation modification (SRM) might reduce rather than increase global climate risk. Using a new damage function and a socio‑political–geophysical tipping‑point framework, it finds SRM is only economically beneficial under very stringent conditions: strong global mitigation, extremely low failure probability, and a slow, well‑managed phase‑out. Any abrupt termination dramatically amplifies catastrophic warming and economic losses. The authors conclude that the governance conditions needed for safe SRM are unlikely in the same world that would resort to using it.
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.
