What regulatory frameworks exist for geoengineering experiments and have any new policies been passed in 2024–2025?
Executive summary
Regulation of geoengineering remains a patchwork: some international instruments and multilateral fora have imposed de facto moratoria or restrictive guidance, while national and subnational authorities are moving unevenly—passing state bans, issuing narrow permits, and debating interagency governance—so there is no single, binding global framework as of 2025 [1] [2] [3]. Between 2024 and 2025 governments and courts sharpened positions—the Convention on Biological Diversity reaffirmed strong restraint on geoengineering affecting biodiversity at COP16 in 2024 and the International Tribunal for the Law of the Sea issued an advisory view warning marine geoengineering could violate UNCLOS—even as U.S. agencies and several U.S. states adopted new laws, guidance, and ad hoc permit actions [4] [1] [3].
1. International instruments: moratoria, advisory opinions and gaps
At the multilateral level the Convention on Biological Diversity (CBD) has acted like a de facto moratorium on geoengineering activities that could affect biodiversity, carving out small-scale, controlled scientific research as the narrow exception—a posture reiterated in 2024 negotiations [1] [4]. Complementing the CBD stance, legal authorities have signaled constraints: the International Tribunal for the Law of the Sea (ITLOS) issued an advisory opinion in 2024 emphasizing that marine geoengineering introducing pollutants or converting one form of pollution into another may breach obligations under UNCLOS [4]. Despite these instruments and opinions, multiple analysts and government reviews conclude there is no comprehensive, binding international agreement specifically governing solar geoengineering research and deployment, leaving major legal and governance gaps at the global scale [2] [5].
2. Regional and national responses: EU, UK and fragmented domestic rules
Regional actors have moved unevenly: the EU’s chief scientific advisers called for an EU-wide moratorium on deployment while recognizing research needs, and the European Commission rolled out carbon removal certification and standards in 2024 that affect carbon dioxide removal projects—measures that create regulatory pathways for some carbon removal activities even as they stop short of legitimizing large-scale solar radiation management [6] [7]. The UK has funded and debated research programmes on “exploring climate cooling,” reflecting a stance of cautious investment in research while regulatory responses are still being shaped [8].
3. United States: patchwork of agencies, state bans, and ad hoc permits
In the United States, governance is fragmented across agencies: OSTP, NOAA, NASA and DOE are tasked with interagency coordination on research governance but statute-driven reports and frameworks have lagged, producing a regulatory grey zone for SRM (solar radiation management) [2] [9]. States have moved faster: Tennessee and other states enacted bans in 2024, and by mid-2025 Florida had passed a law prohibiting acts intended to affect temperature, weather, or sunlight intensity—while numerous other state legislatures considered bills to ban or restrict SRM or research [10] [9] [11]. Federally, the EPA has signaled oversight authority where experiments could involve disposing materials into oceans (MPRSA permitting) and by mid‑2025 had issued at least one MPRSA permit for a marine carbon removal research project while also investigating private balloon SO2 releases from a start-up [3].
4. Science, industry and political pressure: the hidden drivers of policy
Policy developments reflect competing pressures: civil society and many Global South delegations press for prohibition or “nonuse” agreements citing justice and transboundary risk, while research institutions, donor-funded centres, and venture-backed startups press for accelerated experimentation and market pathways—creating incentives for ad hoc, national-level moves rather than coordinated multilateral rules [5] [6] [7]. Critics warn that voluntary carbon markets or commercial certification could become backdoors for commercialization and benefit polluters, a point emphasized by advocacy groups urging stronger international restraint [4].
5. What changed in 2024–2025: concrete policy moves and enduring uncertainty
Concrete changes in 2024–2025 include the CBD’s renewed restrictive posture at COP16 and the ITLOS advisory on marine pollution risk in 2024, multiple U.S. state bans passed or proposed (notably Tennessee in 2024 and Florida in 2025), the EU’s certification for carbon removal in 2024, and nascent agency actions in the U.S. including EPA MPRSA permitting and investigatory letters to private actors—yet these moves amount to a fragmented regulatory mosaic rather than a single governance regime, and analysts warn that international legal gaps and ad hoc national steps leave systemic risk unaddressed [4] [3] [2] [7].