Well, I think that's human's favorite way of getting out of trouble: Let things go to crap, then engineer or brute force an emergency patch.

I'm already on board with geoengineering, especially a program weatherizing rocks in some of unpopulated areas like Nevada. I am a little weary of sea seeding with iron, just because so much of the climate and gas mix is regulated by the ocean...I'd hate to somehow, idk, spur an algae bloom of death world-wide...not that I know anything on the matter.