15. Move to a High-Rise

If you're a true environmentalist, a dyed-in-the-wool greenie, then why not pack up your leafy rural home and move to New York City—preferably to a tall building right in the middle of Manhattan?

The Big Apple is home to the greenest citizens in the U.S. Relatively few New Yorkers own cars—one of the biggest contributors to an individual's carbon emissions. Most walk, bike or ride public transit to work—all more efficient transport than the best hybrids.

And New York has developed up, rather than out, which limits wasteful sprawl. Eight million New Yorkers are squeezed into 301 sq. mi.—less than a fortieth of an acre per person. Even a fairly dense suburb devotes about a third of an acre to each person. Density means that commutes, shopping trips and supply chains are shorter. Plus, New Yorkers tend to live in small spaces, although they're a little cranky about it. The denser the area you call home, the smaller your personal carbon footprint—not to mention your gas and electricity bill.