Actually, his article is self-undermining (misreads the encyclical, thus doing a knee-jerk critique of a straw man, as they say). Also, carbon credits are not recommended by some leading policy researchers, such as Jeffrey Sachs; so, the matter has nothing to do with Catholic theology, contrary to Heath’s opinion.
Sachs notes, in his book:
Emissions permits may (or may not) give more predictability to the future quantities of emissions....[B]ut in fact permit systems are often not very credible, since an expected scarcity of permits (driving up their price) frequently leads governments to increase the allotment of permits. Taxes in general are much easier to administer, while permit systems are in principle easier to configure to meet special interests (e.g., specific favored industries can be given permits for free in order to delay their adjustment to alternative energy sources). [p. 436]But Heath provides a good context for addressing the distance between pastoral appeal (bottom up, so to speak) and mechanics of expert public policy. Yet, the distance is appropriately large, and philosophical theory should need to comprehensively appreciate that distance. The hermeneutical challenge seems vertiginous.
I don’t know when I’ll take time to elaborate about this (importances of technological knowledge that don’t make public policy technocratic), but I’ve archived the “NYTimes Picks” of comments on Heath’s improvisation; so, there’s a good amount of material to work with, besides the very long encyclical.