Warmer periods bring benign rather than more violent weather. Milder temperatures will induce more evaporation from oceans and thus more rainfall -- where it will fall we cannot be sure but the earth as a whole should receive greater precipitation. Meteorologists now believe that any rise in sea levels over the next century will be at most a foot or more, not twenty. In addition, Mitchell flunks history: around 6,000 years ago the earth sustained temperatures that were probably more than four degrees Fahrenheit hotter than those of the twentieth century, yet mankind flourished. The Sahara desert bloomed with plants, and water loving animals such as hippopotamuses wallowed in rivers and lakes. Dense forests carpeted Europe from the Alps to Scandinavia. The Midwest of the United States was somewhat drier than it is today, similar to contemporary western Kansas or eastern Colorado; but Canada enjoyed a warmer climate and more rainfall.