Government Action

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 require a permit from EPA under the Marine Protection, Research and Sanctuaries Act (MPRSA), based on multiple factors such as the location and type of disposition. These approaches have the potential to impact marine environments, including: 

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.

What are EPA’s statutory authorities regarding carbon dioxide removal? 

If a proposed carbon dioxide removal (CDR) activity involves the disposition of material into marine waters, then a permit or authorization from the EPA would likely be required before any such activity could lawfully take place.

Depending on case-specific facts of the proposed marine carbon dioxide removal (mCDR) activity, including the specific type and location of the activity, an EPA administered permit may be required under the Marine Protection, Research and Sanctuaries Act (MPRSA) or Clean Water Act (CWA) Section 402- National Pollutant Discharge Elimination System (NPDES).

Regardless of the applicable statutory permitting program, the permitting process generally includes: 

• An assessment of the project to ensure the proposed activity will not unreasonably degrade the environment or endanger human health.
• Opportunities for public review and comment on the proposed activities. 
• Coordination with other Tribal, federal, state, and local entities as appropriate, including considerations under Clean Water Act 401, Endangered Species Act, Magnuson Stevens Fishery Conservation and Management Act, and Coastal Zone Management Act. 

When is an MPRSA Permit Required?

Unless specifically excluded or exempt from MPRSA, an MPRSA permit is needed to authorize the transportation and "dumping" of any material into "ocean waters". Section 106 of the MPRSA voids any licenses, permits, and authorizations other than MPRSA permits that purport to authorize activities regulated by the MPRSA. An MPRSA permit is not needed for activities that are specifically exempt from permitting under the MPRSA or for the disposition of material from activities that do not occur in ocean waters. 

Examples of mCDR activities that may require authorization under an MPRSA permit include:

• Transportation and disposition of mCDR-related materials into the ocean. For example, transporting alkaline solutions, alkaline minerals or iron solutions or solids to ocean waters via vessel or aircraft and releasing the materials into those waters.
• Transporting and sinking biomass (e.g., macroalgae or terrestrial biomass) by or from a vessel into the ocean.

Additional information about MPRSA permit protections for human health and the environment when evaluating mCDR activities:

• Advancing Safe Scientific Research & Protecting Against Unproven Largescale Geoengineering Activities

MPRSA implements the requirements of the London Convention in the United States

• The London Convention and London Protocol are two international treaties that protect the marine environment from pollution caused by the dumping of wastes and other matter into the ocean.
• Since 2007, the Parties to the London Convention and London Protocol have been working to establish a global, transparent, and effective regulatory mechanism for ocean fertilization and other marine geoengineering activities that fall within the scope of the London Convention and London Protocol.
• Learn more about the work of the London Convention and London Protocol related to marine geoengineering.

When is a CWA Section 402 NPDES Permit Required?

In general, certain discharges from point sources into waters of the United States are regulated under the Clean Water Act and require a National Pollutant Discharge Elimination System (NPDES) permit. mCDR activities that result in the discharge of effluent (e.g., alkaline solution, CO2-depleted water) through an outfall structure into ocean waters, or otherwise are exempt from the MPRSA, are regulated under the Clean Water Act by an NPDES permit that applies the ocean discharge criteria (Clean Water Act section 403) and other Clean Water Act requirements. 

Examples of mCDR activities that may require authorization under a Clean Water Act NPDES permit:

• mCDR-related changes to the effluent discharge at an existing wastewater treatment plant facility (e.g., additions of alkaline solutions or materials). These would be regulated under the NPDES permit for that facility. In this case, the mCDR project applicant would communicate with the current NPDES permittee and the regulatory authority to ensure that any mCDR-related changes in the facility's discharges remain with the scope of the authorization of the existing NPDES permit or whether an NPDES permit modification is necessary because the original permit application did not disclose the mCDR-related change.
• Discharges (e.g., alkaline solutions) not into ocean waters (e.g., internal waters located inside the closing line of a bay, harbor or river mouth) would require NPDES permit authorization rather than authorization under the MPRSA.

Additional Information on NPDES permits: 

• General information about NPDES permits, including FAQs
• More information on permit application forms for EPA-issued NPDES permits

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.