Life occurs, as far as we know, only as part of the earthly biosphere. Yet the earth's biotic resources are experiencing a spreading crisis that is leading not only to the most rapid loss of species in the last 65 million years, but also causing abrupt changes in the structure and function of natural communities. This disturbance, unfortunately, is the result of human carelessness in the name of advancing civilisation. As our technologies and societies continue to improve and grow, we remove ourselves more and more from our natural habitat; as a consequence, we destroy countless numbers of species of every style and complexity. To identify and begin rectifying this dangerous situation, a group of outstanding environmental scientists has compiled a collection of case studies that illustrate the changes being wrought on the biosphere by the human presence.