The World Without Us, a book that considers what would happen to the world if humans disappeared overnight. How long would it take before New York City fell to pieces (not long, the whole of Manhattan would probably be eroded from underneath quickly), what animals would thrive in our absence, and what animals would vanish (no more roaches in New York - they all die because they freeze to death; cattle would likely be easy pickings for predators and so on).
Next I have the June issue of the Magazine of Fantasy and Science Fiction, and then a pile of Arthur C. Clarke stuff to wade through.