Reminds me of a comic I see floated around Facebook from time to time of an auditorium of scientists seated beneath a banner reading "Climate Change Conference," and someone raises their hand and says something to the effect of "But what if we're wrong about climate change and we make a better world for nothing?"
The reduced pollution would probably reduce at least some of the health care costs. Plus we spend way too much on wars and killing people ("defense"). Use some of that money first.
That's not first and foremost CO2, though. Many other forms of pollution tend to be far worse to local environment. Addressing those might involve things like catalytic converters on ships and the like.
