The New York Times: By 2050 or so, the world population is expected to reach nine billion, essentially adding two Chinas to the number of people alive today. Those billions will be seeking food, water and other resources on a planet where, scientists say, humans are already shaping climate and the web of life. In Dot Earth, reporter Andrew C. Revkin examines efforts to balance human affairs with the planet's limits. Supported in part by a John Simon Guggenheim Fellowship, Mr. Revkin tracks relevant news from suburbia to Siberia, and conducts an interactive exploration of trends and ideas with readers and experts.