The document provides an overview of key concepts in environmental science, including:
1) It outlines current environmental conditions such as issues related to population, water, food, climate change, air pollution, and biodiversity.
2) It discusses the historical development of environmentalism in four stages from pragmatic conservation to global environmental citizenship.
3) It describes the divided state of the world between the rich and poor and issues of sustainable development, indigenous people, environmental ethics, and environmental justice.