Under a Green Sky

By looking backward at the course of great extinctions, a paleontologist sees what the future holds.More than 200 million years ago, a cataclysmic event known as the Permian extinction destroyed more than 90 percent of all species and nearly 97 percent of all living things. Its origins have long been a puzzle for paleontologists. During the 1990s and the early part of this century, a great battle ...