I’m not sure how true this is, seeding has been cheap for a long time and no-one’s done it yet. But other techniques like cirrus cloud thinning have been floating around recently (much more difficult).
https://futurism.com/the-byte/scientist-warns-countries-geoengineering
Jack Dorsey’s stepping down from #twitter, so I guess that decentralised #activitypub version of Twitter is vapourware now.