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Which specific state statutes or bills ban solar geoengineering or stratospheric aerosol injection, and what do they prohibit?
Executive summary
State-level activity shows dozens of U.S. bills since 2024 that seek to ban some forms of solar geoengineering or broader “weather modification,” but enacted statutes are far fewer: Tennessee enacted a geoengineering ban in 2024, and reporting by multiple trackers and analysts identifies Florida and Montana as having adopted or passed statutes addressing geoengineering by mid‑2025 — with Florida’s law described as prohibiting acts “intended to affect the temperature, the weather, or the intensity of sunlight” [1] [2] [3]. Major trackers list more than 20 states with bills or proposals, though many are in committee or only passed one legislative chamber [4] [5] [3].
1. What statutes or bills explicitly ban solar geoengineering — the headline list
Multiple reporting and legislative trackers point to three states singled out as having enacted outright bans by mid‑2025: Tennessee (enacted in 2024), Montana, and Florida — though the timing and exact scope differ by source [1] [3] [6]. SRM360 and Duane Morris trackers cover dozens more introduced bills across roughly 20–30 states; Legal Planet and Science News emphasize that while many bills were filed (over 16 or more than 30, depending on cutoff), only a small number had become law or passed one chamber as of spring–summer 2025 [4] [1] [5].
2. What do these laws and bills actually prohibit — common language and differences
Coverage shows two recurring approaches in the statutes and bills: (A) broad bans on “weather modification” that explicitly cover measures “intended to affect temperature, the weather, or the intensity of sunlight,” and (B) narrower bans targeted at “solar radiation management” (SRM) or stratospheric aerosol injection (SAI) specifically. Florida’s new law uses the broader phrasing that encompasses both traditional weather modification (e.g., cloud seeding) and solar geoengineering [2] [7]. Other bills, including some Arizona and Montana proposals, narrow the prohibited conduct to SRM/“injection of stratospheric aerosols” while expressly leaving traditional cloud seeding allowed in some drafts [2] [5] [6].
3. Penalties and enforcement — wide variation and notable examples
Reporting highlights that proposed penalties range from civil fines to criminal sanctions; Florida’s law has been described in media reports as imposing fines up to $100,000 and possible prison time (reporting varies and some outlets emphasize severity) and requires public airports to report aircraft equipped for modification activities [7] [2]. Trackers and analyses stress that bill texts and penalties differ substantially by state, and many bills never reached final form or were amended to narrow scope [4] [5].
4. How precise are the statutory definitions — ambiguity invites controversy
Analysts note many bills conflate or overlap “weather modification” and “solar geoengineering,” and some use charged language tied to longstanding conspiracy beliefs (e.g., “chemtrails”), which has shaped political support for bans in certain states [5] [8]. Legal Planet documents that amendments in several states explicitly defined SRM to include “injection of stratospheric aerosols that increase atmospheric reflectivity,” while other bills used very broad language that could sweep in cloud seeding or other permitted atmospheric research [5] [2].
5. Federal preemption, research exceptions, and practical limits
Available sources emphasize uncertainty about how state bans would interact with federal authority (EPA, FAA) and with small private experiments; for instance, EPA has been actively tracking alleged SRM activity by a start‑up and sent inquiries in 2025, underscoring federal agency interest and potential overlap [9]. Legal analysts caution that many state bills may face enforcement and preemption questions, and that in practice courts and agencies would have to parse statutory language [4] [9]. Sources do not provide a comprehensive, clause‑by‑clause review of each enacted statute’s preemption language — not found in current reporting.
6. What this means for research, deployment, and public debate
Observers and advocacy groups disagree on whether bans will prevent risky experiments or simply politicize an area of nascent science: environmental NGOs and legal scholars call for strict non‑use or moratoria on field experiments [10], while some scientists warn that bans driven by misinformation could stifle controlled research needed to understand risks and benefits [1] [11]. The political drivers vary: some bills are promoted by legislators citing precaution; others draw on chemtrails‑era distrust that amplifies support for bans [5] [8].
Limitations and next steps for readers: This summary relies on legislative trackers and press analyses that summarize many bills; for the exact statutory text, penalties, and preemption language in any specific state (e.g., the exact Florida statute number or Tennessee law text), consult the official state codes or the SRM360 bill tracker cited above — those primary texts are not reproduced in these news sources [4] [2].