What international regulations govern airplane-based geoengineering experiments?

1. Fragmented regulatory landscape: aviation, environment, and research rules

Airplane‑based geoengineering experiments sit at the intersection of aviation safety rules, environmental law, and research governance, which are managed by separate institutions rather than one international regulator. Aviation operational and airworthiness rules (e.g., U.S. Federal Aviation Regulations) govern how aircraft fly and what modifications they may carry, while environmental authorities consider permits and impacts if material is released into air or water; the U.S. EPA says solar geoengineering activities may trigger statutes such as the Marine Protection, Research and Sanctuaries Act and that Congress has not yet passed a law specifically on solar geoengineering ^{[1] [3]}. This means an experiment could face multiple, overlapping approvals rather than one international authorization ^[1].

2. National reporting and weather modification regimes already cover some activities

In the United States, reporting regimes for weather modification extend to solar geoengineering: the Weather Modification Reporting Act requires people intending to engage in weather‑modifying activities to notify NOAA at least ten days before the activity, and the agency tracks such activities under existing rules that explicitly include “solar geoengineering” when it involves release of gases, dusts, liquids, or aerosols ^[1]. EPA guidance also flags that federal agencies (NOAA, OSTP, NSF, DOE) were directed to develop research plans for rapid climate interventions and that any research must consider human‑health and ecosystem impacts ^[1]. These domestic reporting and planning steps illustrate how national systems try to fit novel experiments into existing statutory buckets ^[1].

3. Practical regulatory gaps and evolving government action

U.S. authorities acknowledge gaps: EPA notes Congress has not enacted a solar‑geoengineering‑specific law and agencies are evaluating whether new statutory authority or a lead agency is needed to regulate or enforce activities ^[1]. The Biden Administration’s-directed planning and the 2023 federal research plan cited by EPA show government-level attention, but they do not equate to binding global rules — they are domestic frameworks meant to guide research and oversight ^[1]. Other national aviation regulators and civil‑aviation rulemaking (e.g., FAA rulemaking and civil aviation standards) could also affect whether and how aircraft can be used for experiments, yet the provided materials focus on U.S. and aviation regulatory processes rather than an international treaty ^{[1] [3]}.

4. Academic proposals raise urgency but do not create legal authority

Recent modelling work proposes that existing large aircraft could deliver particles to reflect sunlight, lowering technical barriers to experiments and heightening the need for governance ^[2]. University College London researchers explicitly caution that solar geoengineering “comes with serious risks and much more research is needed,” signalling that the scientific community expects policy and regulatory scrutiny even as feasibility studies appear ^[2]. However, the academic proposal itself does not change the legal status; it creates political and regulatory pressure without a global rulebook ^[2].

5. International institutions and missing global treaty in current reporting

Available sources do not describe a dedicated, binding international treaty that specifically governs airplane‑based geoengineering or solar radiation modification experiments; instead reporting points to national statutes, agency guidance, and international scientific discussion ^{[1] [2]}. The provided materials do not mention explicit International Civil Aviation Organization (ICAO) rules or a United Nations convention that authorizes or bans such experiments; thus “not found in current reporting” about a single international instrument ^{[1] [3]}.

6. Competing perspectives and risks to watch

Advocates for research emphasize the need to understand risks and technical feasibility ^[2]. Critics and activist sources in the provided results frame geoengineering as an ongoing or clandestine practice and warn of environmental harm, though these sources (e.g., Geoengineering Watch, Activist Post) are advocacy outlets raising alarm and claims about “spraying” that the other, scientific and regulatory documents do not substantiate ^{[4] [5] [6]}. Policymakers must weigh scientific uncertainty, transboundary impacts, and public consent — an argument underscored by EPA’s call for research that includes human‑health and international engagement considerations ^[1].

7. What to expect next in governance

Expect policy development rather than a sudden treaty: national regulators (environmental and aviation authorities) are likely to refine reporting, permitting, and risk‑assessment requirements; research funders and interagency plans will shape domestic research programs; and academic findings demonstrating operational feasibility will increase calls for international discussion even if not yet producing binding global rules ^{[1] [2]}. The available sources show evolving domestic attention and scientific impetus but do not indicate a consolidated international regulatory regime at this time ^{[1] [2]}.

Limitations: this analysis uses only the supplied sources and therefore does not include other international drafts, ICAO deliberations, UN instrument developments, or national laws outside those cited; available sources do not mention a single global treaty specifically governing airplane‑based geoengineering ^{[1] [2]}.