Solar Radiation Modification challenges decarbonization with renewable solar energy

Abstract. Solar Radiation Modification (SRM) is increasingly being discussed as a potential tool to reduce global and regional temperatures to buy time for conventional carbon mitigation measures to take effect. However, most simulations to date assume SRM as an additive component to the climate change toolbox, without any physical coupling between mitigation and SRM. In this study we analyse one aspect of this coupling: How renewable energy (RE) capacity, and therefore decarbonization rates, may be affected under SRM deployment by modification of photovoltaic (PV) and concentrated solar power (CSP) production potential. Simulated 1-hour output from the Earth System Model CNRM-ESM2-1 for scenario-based experiments are used for the assessment. We find that by the end of the century, most regions experience an increased number of low PV and CSP energy weeks per year under SAI (Stratospheric Aerosol Injections) compared to the moderately ambitiously mitigated scenario SSP245. Compared to the unmitigated SSP585 scenario, while the increase in low energy weeks is still dominant, some areas see fewer low PV or CSP energy weeks under SAI. A substantial part of the decrease in potential with SAI compared to the SSP-scenarios is compensated by optically thinner upper tropospheric clouds under SAI. Our study suggests that using SAI to reduce high-end global warming to moderate global warming could pose increased challenges for meeting energy demand with solar renewable resources.