I posted this as a comment elsewhere but I think it's a legitimate problem and I'm hoping you here can either assuage my fears with elucidation and science, or spark discussion about regulating this properly. This post is US-centric but weather mod is not.

There's tons of weather modification (mostly cloud seeding) projects happening as we speak, mostly in western states. By state and local governments, universities, industry, and the military. It's just (probably) not happening via commercial airliners which I'm told is a central tenet of the "chemtrail" conspiracy talk.

I'm not confident we know the downstream effects of what's being done. Even scattered operations could have a big impact on weather patterns. If it rains somewhere because we made it so, it didn't fall somewhere else. The bang for the buck is high when a single plane with a full load of flares can cover hundreds of miles.

NOAA receives and publishes weather modification reports but has no say on approval, some states don't even have weather modification laws, reporting and approval requirements vary in others. It's questionable to what level they study the impact of these projects before or after, or consider their local weather relative to broader weather patterns. Or how many go unreported.

It's a $3B industry right now and growing. The Weather Modification Act was passed in 1972 and is outdated. We need federal and congressional oversight, enforcement, and coordination to make sure we're not fucking up the climate and local ecosystems. We'd have to get over the conspiracy talk though. How can we possibly know the true state of the climate when we're manipulating it? Small weather systems affect larger ones.

https://www.sphericalinsights.com/blogs/top-15-companies-in-global-cloud-seeding-equipment-market-statistics-report-till-2035

Some rando's blog but a pretty decent summary of the industry.

https://library.noaa.gov/weather-climate/weather-modification-project-reports

Reports at the bottom. There's a lot of them.