State of the Science Fact Sheet: Solar Radiation Modification

Solar Radiation Modification (SRM) refers to deliberate, large-scale actions intended to decrease global average surface temperatures by increasing the refection of sunlight away from the Earth. Proposed SRM methods involve the use of aerosols (small particles) or other materials to increase the reflectivity of the atmosphere, clouds, or Earth’s surface. These methods have the potential to lower surface temperatures more quickly than carbon dioxide removal (CDR) methods and reduce some risks posed by climate change, while posing other risks still to be understood. The single largest driver of climate change in the industrial era has been human-caused emissions of carbon dioxide (CO2), a long-lived greenhouse gas (GHG). Long-term protection of Earth’s climate and oceans requires substantial reductions in emissions and atmospheric concentrations of CO2 and other GHGs. SRM is not considered a substitute for climate mitigation efforts, which include decarbonization and GHG emission cuts. SRM research is being conducted as a response to growing concerns that the pace of CO2 emissions reductions and CDR technology development is not sufficient to avoid severe impacts of climate change in the next decades. Research into the viability and effectiveness of SRM methods and potential unintended consequences provide a foundation for decisions regarding the implementation of SRM.