Comment by siffin
I don't think it's the environmentalists stopping atmospheric tampering, it's other things like the economics of it, or some countries being very against it.
Geoengineers have talked seriously about this for a long time, but it's a mostly a political issue, then who actually wants to pay to do the science and pay for the outcomes, when you've got no real idea who will get destroyed in the long run.
Is Europe going to help fund it, with a consequence being they have less rainfall? Nobody really knows, so no one really wants to pay to do it at scale, forever.