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What are EPA’s statutory authorities regarding solar geoengineering?
What does the U.S. government do regarding research and tracking of solar geoengineering?
What are EPA’s statutory authorities regarding solar geoengineering?
EPA is doing everything within its authority to identify and track any potential solar geoengineering or solar radiation modification (SRM) activities within the United States. For example, on April 15, 2025, EPA’s Office of Air and Radiation (OAR) sent a request to a start-up company called “Make Sunsets,” which claims to be geoengineering the planet by releasing balloons filled with sulfur dioxide (SO2) and selling “cooling credits.” As of May 2025, Make Sunsets reported releasing about 0.1 tons of SO2 into the stratosphere. Even though that amounts to an extraordinarily low amount of SO2, EPA is conducting an internal review of any current authorities that can be utilized to halt this activity, especially if it significantly scales up. Alternatively, it is being determined whether new authorities would be needed from Congress, or whether another agency should take the lead in regulating and enforcing against such activities.
In addition, any persons planning to engage in solar geoengineering activities that may result in the disposition of material into ocean waters or onto sea ice may need to submit a permit application to EPA under the Marine Protection, Research and Sanctuaries Act (MPRSA), based on multiple factors such as the location and type of disposition. As of July 2025, EPA has issued one MPRSA permit for a marine carbon dioxide removal research project. These approaches have the potential to impact marine environments, including:
Toxicity of introduced materials to marine organisms
Decreased ecosystem productivity due to decreased sunlight (i.e., energy) reaching the environment
And other impacts depending on the specific materials or methods used and the scale of the activities, including impacts outside of the immediate geographic area where the activities are conducted
What does the U.S. government do regarding research and tracking of solar geoengineering?
Congress has not passed any law solely related to solar geoengineering, though several statutes are relevant. For example, under the authority of the Weather Modification Reporting Act (WMRA) of 1972, all persons intending to engage in weather modification activities in the United States are required to provide a report to the National Oceanic and Atmospheric Administration (NOAA) at least 10 days prior to undertaking the activity. Under Part 908.3 of Title 15 of the Code of Federal Regulations, reporting requirements for weather modification encompass solar geoengineering activities “modifying the solar radiation exchange of the earth or clouds, through the release of gases, dusts, liquids, or aerosols into the atmosphere.” While NOAA does not regulate weather modification activities, it does track them through WMRA reporting requirements. A public database of NOAA weather modification reports can be viewed here: Weather Modification Project Reports. For more information on weather modification and how it relates to geoengineering, see the frequent questions.
In 2022, Congress directed the Office of Science and Technology Policy (OSTP), with support from NOAA and in coordination with the National Science Foundation (NSF) and the Department of Energy (DOE), to develop a five-year federal research plan for “solar and other rapid climate interventions.” [1] The resulting 2023 Biden Administration Report to Congress (pdf) (923 kb) concluded that the development of a federal research program on solar geoengineering would help to better inform decisions on the potential risks and benefits and help prepare for possible deployment by other public or private actors. The report also emphasized that any solar geoengineering research program should encompass both the scientific dimensions of solar geoengineering as well as the potential impacts to human health and well-being, ecosystems, and international engagement.
Starting in Fiscal Year 2020, NOAA received direction from Congress to conduct research on natural events and human activity that could change the Earth’s radiation budget (ERB), including solar geoengineering. [2] To date, NOAA is the only federal agency that has received funding explicitly to study SRM. Since 2020, NOAA’s ERB Program has initiated various research activities on solar geoengineering, such as atmospheric modeling, stratospheric observations, and laboratory activities to understand the physical impacts of stratospheric aerosol injection (SAI) and marine cloud brightening (MCB).
In 2022, NOAA’s ERB Program jointly hosted a workshop with DOE to identify research gaps related to Marine Cloud Brightening (MCB). In 2024, Congress further directed NOAA “in coordination with NASA and the Department of Energy, as appropriate, to improve the understanding of the impact of atmospheric aerosols on radiative forcing, as well as on the formation of clouds, precipitation, and extreme weather and to develop plans for sustained observations of the stratosphere. [3] Further, NOAA is encouraged to coordinate with NASA for long-range crewed and autonomous in situ atmospheric observational capabilities.” Relatedly, NOAA and NASA have coordinated on sampling aerosol in the lower stratosphere, for example, as part of the Stratospheric Aerosol processes, Budget and Radiative Effects (SABRE) project using the NASA WB-57 high-altitude research aircraft.
NSF has solicited research proposals specifically related to geoengineering. No projects were ultimately funded under this 2023 solicitation, but NSF has previously funded other research grants relevant to solar geoengineering.
Current federal research is designed to improve the ability to observe current conditions in the atmosphere and the understanding of the potential physical impacts of solar geoengineering. The U.S. government is not engaged in any form of outdoor testing (e.g., small-scale experiments designed to study injection technologies) or large-scale deployment (e.g., intentional use of SRM to cool the Earth). Current federal research activity should not be interpreted as endorsement of the implementation of SRM.
References
1 Consolidated Appropriations Act, 2022 (pdf) (41 mb) H.R. 2471; P.L. 117–103, p. 233.
2 PROCEEDINGS AND DEBATES OF THE 116th CONGRESS, FIRST SESSION(pdf) (19.3 mb) Vol. 165 WASHINGTON, TUESDAY, DECEMBER 17, 2019 No. 204—Book II, p. H10963.
3 Senate Report 118-62. DEPARTMENTS OF COMMERCE AND JUSTICE, SCIENCE, AND RELATED AGENCIES APPROPRIATIONS BILL(pdf) (638 kb) 2024., July 13, 2023, p. 48.