Abstract:

Solar geoengineering (also sunlight reflection or solar radiation modification, SRM) is a potential climate response that would cool the Earth’s surface by scattering one or two percent of incoming sunlight. SRM can only imperfectly correct the effects of elevated greenhouse gases, but might complement other climate responses to reduce risks, while also bringing new risks and challenges to global governance. SRM is receiving increased attention and controversy, with many calls for expanded research and governance consultations, along with ongoing concerns about risks, control, misuse, and over-reliance. I will provide a brief overview of SRM’s history, methods and uses, and the current status of research on efficacy and impacts, mainly focusing on the most prominent and promising approach, stratospheric injection of sulfur aerosols (SAI). SAI presents several long-standing concerns and controversies. I will discuss the status of these and how they relate to results from advancing research on potential interventions and impacts, including discussion of a few significant recent events and speculative reflection on near-term trends in research, governance, and debate on SRM’s potential role in response to climate change.