I personally side with carbon taxes for a number of reasons, but I wonder something about cap-and-trade schemes. Why have environmental groups not been devoting large amounts of money to buy and retire pollution credits in the current markets? (Perhaps they have been and I have been ignorant of what has been going on.) I would think that those kinds of expenditures would be easy to justify to contributors (and eventually moot arguments about effective "carbon offsets").
--tim francis-wright