How many times has your mother told you to turn off the lights when you leave a room, or to close the fridge door while you decide what to eat. Well, climatologists are on her side. Because according to a study in the Proceedings of the National Academy of Sciences, reducing global carbon emissions should begin at home. Even if politicians manage to pass climate change legislation, it could be years or even decades before those policies start to make a difference. In the meantime, scientists say, there are things we can all do to shrink our carbon footprint. You've heard most of 'em before: everything from insulating your home and using low-flow showerheads to driving more efficient vehicles and carpooling to the office. But these things really work. Based in part on how folks responded to the energy crisis in the '70s, the scientists calculated how many Americans might be willing to reform their energy-wasting ways.