According to University of Washington paleontologist Peter D. Ward, all but one of the major extinction events in the history of the world have been brought on by climate change--the same global warming that occurs today. In Under a Green Sky, he examines the causes of the Permian extinction, an event more than 200 million years ago so cataclysmic that it destroyed more than 90% of all species and nearly 97% of all living things. This near-total devastation was caused by a warming of the earth due to rising levels of carbon dioxide.

Ward explains how that extinction, as well as four others, happened, and then applies those chilling lessons to the present day, showing how the ancient past may hold the key to earth's future.