Book excerpt: Scientists have long sought to unravel the fundamental mysteries of the land, life, water, and air that surround us. But as the consequences of humanity's impact on the planet become increasingly evident, governments are realizing the critical importance of understanding these environmental systemsâ€"and investing billions of dollars in research to do so. To identify high-priority environmental science projects, Grand Challenges in Environmental Sciences explores the most important areas of research for the next generation. The book's goal is not to list the world's biggest environmental problems. Rather it is to determine areas of opportunity thatâ€"with a concerted investmentâ€"could yield significant new findings. Nominations for environmental science's "grand" challenges were solicited from thousands of scientists worldwide. Based on their responses, eight major areas of focus were identifiedâ€"areas that offer the potential for a major scientific breakthrough of practical importance to humankind, and that are feasible if given major new funding. The book further pinpoints four areas for immediate action and investment.