Over the last half billion years, there have been five major mass extinctions, when the diversity of life on Earth suddenly and dramatically contracted. Scientists are currently monitoring the sixth extinction, predicted to be the most devastating since the asteroid impact that wiped out the dinosaurs. This time around the cataclysm is us. In this book the author tells us why and how human beings have altered life on the planet in a way no species has before. She provides a moving account of the disappearances of various species occurring all around us and traces the evolution of extinction as concept, from its first articulation by Georges Cuvier in revolutionary Paris up to Lyell and Darwin, and through the present day. The sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human. -- Publisher description.

Fully updated throughout, including revised illustrations and new images from NASA missions, this new edition provides an overview of Earth's history from a planetary science perspective for Earth science undergraduates. Earth's evolution is described in the context of what we know about other planets and the cosmos at large, from the origin of the cosmos to the processes that shape planetary environments and from the origins of life to the inner workings of cells. Astronomy, earth science, planetary science and astrobiology are integrated to give students the whole picture of how the Earth has come to its present state and an understanding of the relationship between key ideas in different fields. The book presents concepts in nontechnical language and mathematical treatments are avoided where possible. New end-of-chapter summaries and questions allow students to check their understanding and critical thinking is emphasized to encourage students to explore ideas scientifically for themselves.

"Discerning Experts assesses the assessments that many governments rely on to help guide environmental policy and action. Through their close look at environmental assessments involving acid rain, ozone depletion, and sea level rise, the authors explore how experts deliberate and decide on the scientific facts about problems like climate change. They also seek to understand how the scientists involved make the judgments they do, how the organization and management of assessment activities affects those judgments, and how expertise is identified and constructed."--cover.