re: #3 LudwigVanQuixote

Putting sulfur in the air means sulfuric acid rain. That kills the flora that would do the scrubbing of the CO2. That is a very bad idea.

I’m not a climate scientist, but Paul Crutzen is. wikipedia on Paul Crutzen.

He has a Nobel prize. If there’s a reason why it’s a bad idea, it has to be a pretty subtle one because Nobel prize winners are not utter fools in their own area of expertise. As always with poisons, the dose makes the poison. Putting a little sulfur in the air is different from putting in more. If we could get a big enough bang of cooling for a small enough buck of sulfur pollution, the idea could be workable.