The German cautionary tale is also worth noting... the 400 billion in investment has the expected potential return of about 200-300 billion, that's based on reasonable assumptions.
So, to illustrate and analogize the question; why don't you give a 100$ bill to each homeless you walk past each day? I mean if you want to do good things regardless of the reason (in this analogy the reason would be to not also donate yourself into homelessness)
Look up the new forests initiative and their work enforcing these carbon trading schemes in countries like Rwanda, Uganda, and other countries. This is a UN program to control the carbon trading where countries that produce most co2 will buy carbon offsets from third world countries.As to the carbon trading, I agree to some extent, but it's worked well (or so I've read) on a smaller scale with other kinds of emissions.
*spoiler alert: it might shake your view on the good that comes from these programs *