The research paper Extinction Risk from Climate Change published in the journal Nature in January 2004 created front-page headlines around the world. The notion that climate change could drive more than a million species to extinction captured both the popular imagination and the attention of policymakers, and provoked an unprecedented round of scientific critique. Saving a Million Species reconsiders the central question of that paper: How many species may perish as a result of climate change and associated threats? Leaders from a range of disciplines synthesize the literature, refine the original estimates, and elaborate the conservation and policy implications. This book examines the initial extinction risk estimates of the original paper, subsequent critiques, and the media and policy impact of this unique study. It presents evidence of extinctions from climate change from different time frames in the past. It explores extinctions documented in the contemporary record. It sets forth new risk estimates for future climate change. It considers the conservation and policy implications of the estimates. Saving a Million Species offers a clear explanation of the science behind the headline-grabbing estimates for conservationists, researchers, teachers, students, and policymakers. It is a critical resource for helping those working to conserve biodiversity takes on the rapidly advancing and evolving global stressor of climate change - the most important issue in conservation biology today, and the one for which we are least prepared.