Oil and gasoline use is diffuse, scattered in the global crowd. The world has 1.3 billion vehicles and perhaps 1.5 billion households. Cutting emissions from these cars and homes means changing the daily lives of billions of people, a mind-boggling thought. Reducing global coal emissions, by contrast, means dealing with 3,300 big coal-fired power plants and several thousand big coal-driven steel and cement factories.*10 The task is huge, but it is at least imaginable--and it targets almost half of the world's emissions at a stroke. Fix coal, the idea is, then go, if needed, to the next thing. That's the way to insure against the small but real possibility of catastrophe.