Earth in Peril

City Lights of the World, 1998
Populations are becoming increasingly urbanized. Thirty years ago, only 37 percent of all people lived in cities. Experts predict that by 2030, over 60 percent of the population—five billion people—will do so. The largest share of this escalation will occur in countries where the demand for clean water, sewage systems, and electricity already outstrips supplies. Greater urbanization may have a few environmental benefits, such as reduced pressure on forests, but the costs of the trend are great. City populations consume vast amounts of energy and create air and water pollution affecting human health, local natural habitats, and the global environment.