It had been a while since I'd watched a Thunderf00t video, so I thought I'd watch a new one to see if he still squeals "Weeelll....". Thankfully, no.
The problem is injecting aerosols (I hear the Annunaki used Gold) into the atmosphere much higher than airplanes fly. What occurs to me is a Falcon or Starship custom suborbital 2nd stage. If it went up but not to orbital velocity it would loft much more payload.
A thousand launches of 100 tons each (average) would be 100,000 tons a year.