Seven billion humans are alive today, up from one billion in 1900, and the environment is taking a beating. What's next? Nine-plus billion by 2050? Eleven billion? But what happens to these numbers if we educate and empower women? If we provide family planning services? What's stopping us? In "Soaring Past 7 Billion: Population Challenges for a Crowded World," John Seager, president of Population Connection, addresses these issues.