Which US states have proposed or passed bans on solar geoengineering?
Executive summary
State legislatures across the U.S. have introduced a wave of proposals restricting solar geoengineering in 2024–25, with reporting that between “over 16” and 34 states have proposed bans and three states — Tennessee, Florida and Montana — reported in multiple sources as having enacted bans or laws touching geoengineering (see ScienceNews, Just Security, Carnegie) [1] [2] [3]. Coverage varies by outlet and date: some trackers count 22 states with bills in 2025 (SRM360) while others report as many as 34 states proposing bans [4] [2].
1. What the headline numbers mean: different tallies, different definitions
Counting “states that have proposed or passed bans” depends on how a source defines geoengineering and what it includes: broader “weather modification” bills, narrow “solar radiation management” (SRM) bans, or measures that refer to chemtrails rhetoric. One tracker reported 22 states introducing bills in 2025 [4]; ScienceNews says “over 16” states had introduced bans in the first three months of 2025 and notes Tennessee passed a ban in 2024 [1]. An advocacy/analysis piece reports 34 states with proposed bans and names Tennessee, Louisiana and Florida as having passed bans [2]. The discrepancy reflects inconsistent definitions and rapidly changing legislation [4] [1] [2].
2. Which states are consistently reported as having passed bans
Multiple outlets flag Tennessee as an early adopter: ScienceNews cites a Tennessee ban enacted in 2024 [1]. Other reporting lists Florida and Montana alongside Tennessee as states that have enacted outright bans or laws targeting geoengineering [3] [2]. Florida’s 2025 legislation is documented in a state analysis that sets an effective date and tasks enforcement agencies with implementing reporting and bans [5]. Sources disagree on the exact list and timing, but Tennessee and Florida are repeatedly identified [1] [5] [3].
3. Why many states are moving now: politics, fears and “chemtrails”
The surge in bills is driven by a mix of genuine policy caution about unknown environmental and health risks and by political currents that conflate nascent science with conspiracy narratives. Reporting notes many of the bills come from Republican-led legislatures and are tied to chemtrails rhetoric and public skepticism about atmospheric interventions [1] [3] [6]. Advocacy groups calling for bans stress precaution because of unpredictable impacts and power imbalances in deployment decisions [7].
4. The substance of state bills: moratoria, narrow SRM bans, or broad weather-modification prohibitions
Legislation varies: some bills ban “solar radiation management” specifically while preserving traditional weather modification (e.g., cloud seeding), others prohibit a wide range of actions “intended to affect temperature, weather, or intensity of sunlight” [8] [5]. The EPA notes that some state bills explicitly exclude cloud seeding while targeting SRM; it also documents Florida’s 2025 law as prohibiting acts intended to affect temperature or sunlight [8]. That variance changes which activities are actually restricted on the ground.
5. Who is tracking this and how reliable are the counts?
Advocacy sites, mainstream outlets and policy groups produce different tallies: SRM360 reported 22 states introducing bills in 2025 [4]; ScienceNews counted “over 16” in early 2025 and identified Tennessee’s 2024 law [1]; a Just Security analysis claimed 34 states had proposed bans and listed Tennessee, Louisiana, and Florida as enacting bans [2]. The Carnegie piece synthesizes many of these reports and states three outright bans (Florida, Montana, Tennessee) while noting 22 states have anti–solar-intervention legislation in play [3]. Differences reflect timing, methodology and whether authors include bills that target “chemtrails” or narrow cloud‑seeding exceptions [4] [1] [3].
6. What coverage leaves out or glosses over
Available sources do not provide a single, authoritative federal inventory tying every bill by state and precise statutory language in one place; they also differ on whether to count draft bills, committee measures that died, or laws with limited scope [4] [2] [1]. EPA materials document some state actions and note related federal reporting requirements, but the patchwork character of state-level lawmaking means a clear, stable national count is not present in current reporting [9] [8].
7. Bottom line for readers
State-level activity is widespread and accelerating, but the exact number of “proposed or passed bans” depends on definitions and timing: authoritative trackers cite figures from “over 16” to 34 states, while multiple sources consistently identify Tennessee and Florida (and in some reporting Montana or Louisiana) as states that have passed bans or restrictive laws [1] [5] [2]. Readers should treat headline counts cautiously and consult the full text of individual state bills for precise scope and enforcement details — existing coverage shows the movement is real, but messy and politically charged [4] [1] [3].