Designed as an undergraduate textbook, this work investigates our dependence on the integrity of the Earth's ecosystems. It presents an introduction to human ecology, discusses the principles of ecologically sustainable development, and investigates the foundations of ecological economics. It also evaluates biodiversity, assesses the effects of trade on the environment, and analyzes the ethical considerations of ecological economics. Using case studies, the authors investigate the greenhouse effect, soil erosion and the environmental and ecological impact of current economic analysis.