The Earth's climate is changing due to human activities. Recent polls suggest that the U.S. public generally recognizes this fact, and the efforts that led the Intergovernmental Panel on Climate Change (IPCC) and former U.S. vice president Al Gore to win the 2007 Nobel Peace Prize have played no small role in bringing most of the public to realize what scientists have been discussing for years. Yet aside from distorted Hollywood movie accounts such as The Day After Tomorrow, the public knows little about the potential for abrupt change in the climate system. With support from climate science philanthropist Gary Comer, climate scientist Wally Broecker has teamed with science writer Robert Kunzig in this book to bring abrupt climate change into public view. They do this elegantly and convincingly, making the first 12 chapters quite enjoyable.