Complex systems is a new field of science studying how parts of a system give rise to the collective behaviors of the system, and how the system interacts with its environment. This book examines the complex systems involved in environmental sustainability, and examines the technologies involved to help mitigate human impacts, such as renewable energy, desalination, carbon capture, recycling, etc. It considers the relationships and balance between environmental engineering and science, economics, and human activity, with regard to sustainability.