Well, after searching, it appears there is a book that does exactly this. I'm going to read it, and then maybe I will have a better idea of what the relative cost benefits are.
"How to Spend $75 Billion to Make the World a Better Place" - I'm about halfway through, but according to this Copenhagen consensus group, which appears to be made up of Nobel prize-winning scientists, the ROI for global warming mitigation is negative (using the same methodology they applied to the other items they were considering).
https://www.amazon.com/gp/digital/fiona/thank-you?ie=UTF8&a=...