The expected effects of a sea-level rise typify the many consequences of a global warming. On the one hand, they are so big we literally can't understand them. If there is a significant polar melting, the Earth's center of gravity will shift, tipping the globe in such a way that the sea level might actually drop at Cape Horn and along the coast of Iceland-I read this in a recent EPA report and found that I didn't really understand what it meant to tip the Earth, through I was awed by the idea. On the other hand, the changes ultimately acquire a quite personal dimension: Should I put in a wall in front of my house? Does this taste salty to you? And, most telling of all, the human response to the problems, the utterly natural human attempt to preserve the old natural way of life in this postnatural world, creates entirely new consequences. The ocean rises; I build a wall; the marsh dies, and, with it, the fish.