Unless something dramatically changes about the way humans interact with the world and the products, processes, and systems we design, we will end up exactly where we are headed-an unsustainable future. New challenges are arising that are more subtle, more complex, more global, and potentially more devastating to people and the planet. For these and other reasons, environmental engineering has now emerged as a distinct discipline, and the creativity and diligence that characterizes the field has resulted in tremendous benefits to the environment and improved quality of life.