Carbon credits are a mechanism by which excessive pollution is supposedly legitimized by other actions. It's a rather nefarious scheme IMHO. We should treat the activities of governments, companies and other organizations in a disaggregated fashion: Pumping out CO_2 and other pollutants into the air should be penalized, and engaging in CO_2-and-methane-sequestering activity (e.g. forestation) should be encouraged, independently of one another.