This book will present an earth science-based overview of the challenges to sustainability (climate change, food and water shortages, etc.) and offer potential solutions. It will show how to use footprint analysis to estimate the environmental impacts of human activities, which then allows us to prioritize problems and their solutions. "John Ayers has addressed one of the issues of our time (maintaining human life on earth) and clarified the meaning of the overused word sustainability. Using his experience as a geochemist, he has given us clear descriptions of the issue facing us and logically outlined possible scenarios in an easy-to-read text."- Frank Elliott, University of Alberta, Canada "This is a truly outstanding state-of-the-art review of the sustainability literature. The book provides an exceptional and insightful synthesis of theories, observations, and new ideas relevant to the study of sustainability in the context of the environmental sciences. It will inspire a wide community of students, scholars, and practitioners both from the natural and social sciences." -Paolo D'Odorico, University of Virginia, USA