Over 4.5 billion years, Earth’s climate has transformed tremendously. Before our more temperate recent past, the planet swung from one extreme to another—from a greenhouse world of sweltering temperatures and high sea levels to a “snowball earth” in which glaciers reached the equator. During this history, we now know, living things and the climate have always influenced and even shaped each other. But the climate has never changed as rapidly or as drastically as it has since the Industrial Revolution. In this lively and entertaining book, Donald R. Prothero explores the astonishing connections between climate and life through the ages, telling the remarkable stories of the scientists who made crucial discoveries. Journeying through the intertwined evolution of climate and life, he tackles questions such as: Why do we have phytoplankton to thank for the air we breathe? What kind of climate was necessary for the rise of the dinosaurs—or the mammals, their successors? When and how have climatic changes caused mass extinctions? Prothero concludes with the Ice Ages and the Holocene, the role of climate in human history, and the perils of anthropogenic climate change. Understanding why the climate has changed in the past, this timely book shows, is essential to grasping the gravity of how radically human activity is altering the climate today.