Research on the ecosystems has emerged in recent decades as a vital, successful, and sometimes controversial approach to environmental science. Ecosystem science has addressed issues such as human alteration of biogeochemical cycles, ecological complexity and biodiversity, and ecological response to climate change. As a central and integrating science, ecosystem-level studies have been highly successful. This book emphasizes the idea that much of the progress in ecosystem research has been driven by the emergence of new environmental problems that could not be addressed by existing approaches. By focusing on successes, limitations, and frontiers in ecosystem studies, it will be welcomed by students and scientists throughout the ecological and environmental communities.