One must deal with humans as they are, not as we'd wish them to be. The correct solution is that externalities associated with consumption should be priced in by fiat. The government has the (uneviable) task of protecting the environment because it is a perfect example of a common good. Of course, such authority must be given to the government by the people; it is already happening to a very small extent; as climate change becomes more real to people's everyday lives, I expect to see more movement in this direction. Of course, by then it will probably be too late, but we can hope that it will not be.