"Crisis" mode eh - once that's on the cards then you can push all sorts of things through. You should look into the termination issues with geoengineering (once you pop, it's very hard to stop). Also.. there will likely be trade off zones where the climate will get very bad. Under some models you shaft parts of Africa, but if you do things other ways then you can stuff N. America. Who gets to decide?

Have a read of "This changes everything". Do we _really_ want to go to geoengineering and, frankly, gamble that we've got it covered. I don't like that idea.