ABSTRACT
At night, Earth’s cities are visible from space as stars or chains of light in a sea of blackness. Many appear to be vibrant and to exude energy. People are drawn to the “lights on Broadway,” for example. But a closer examination reveals complex webs of streets, enormous buildings, vehicles, and burgeoning populations-all of which need energy to build, use, and sustain. To meet these needs, cities draw energy from the world around them, providing local benefits-but with health, security, and environmental consequences for all.
