The book which is reviewed here makes a point that contradicts our assumptions.
Green Metropolis by David Owen points out that New York City produces less greenhouse gases per capita than any state in the country. Living in suburbia and recycling may make you feel moral. Living in Manhattan, walking nearly everywhere and taking public transit for the rest has you behaving morally.
It's an intetresting take. ai'd like to see more of this sort of discussion. Mostly what I see is people who bike to work once a week.