Ecology for the 21st Century is a comprehensive, beginner-friendly, introductory textbook that provides students with an ecological perspective on our changing world. Suitable for both non-majors and majors-level ecology courses, this textbook presents clear and wide ranging coverage, including many current examples and topics. Applying a student-centric approach with dynamic examples and case studies, the book's ecological principles emerge through topics students care to learn more about. The ‘twin-evils’ of atmospheric carbon and ocean acidification are explored through investigations on the health of coral reef ecosystems. In addition, populations and species dynamics are introduced using classical modeling parameters. This textbook drives home the delicate balance of the natural world through regional issues surrounding endangered versus invasive species. Themes of resource acquisition, adaptation, and evolution of species are reinforced throughout, encouraging students to envision an ecologically driven world.