These carbon ration cards bring to mind the "karma cards" in Jonathan Lethem's Gun, with Occasional Music.
Perhaps the two concepts will merge one day. If you run afoul of The Man -represented in the novel by futuristic police and boneheaded inquisitor-bureaucrats -he can deduct points from your karma card. Run out of karma and you go into the deep freeze for 6 years.
That would definitely cut down your carbon emissions.