Sounds like climate scientists need to read a lot into the epistemology of economics. (It may well be that "economic science" is an oxymoron, but the work that has been done to try and make it one...)
One problem with all of these approaches is they require more then one subject. Unfortunately we only have one earth, so there is no way to have a natural control without CO2 rising, or an earth where the CO2 rose at a different time.