The human population on Earth continues to increase, raising concerns over the ability of the planet to accommodate its inhabitants. The impact that life has on the dynamic processes of Earth, a changeable planet, and its material cycling are studied in Environmental Science. In the coming years, Environmental Science will become a more important part of every human's education to keep both the population and the planet in healthy balance with each other. Environmental Science combines elements of Earth Science with ecology, evolution, and technology to educate humanity on the pressing concerns of our planetary host. While Earth is an ideal place for our home, it has its limits and demands to continue a healthy relationship with its living inhabitants. The rapid expansion of the human population in recent centuries does not seem likely to lessen until environmental catastrophes or technological breakthroughs occur. Obviously, we all hope for technology that will avert a catastrophe, yet rational decisions based on real science must constitute the major thrust of any strategy for environmental sustainability. Familiarity with the environmental issues therefore becomes a major responsibility of all citizens of Planet Earth.