Note: This article is part of a collaboration between Island Press and Public Square on a series of articles based on recently published books on subjects related to urbanism.
Cities affect our lives in profound, self-reinforcing ways: they can be a source of economic innovation, a pathway for poverty reduction, a brake on logarithmic demographic growth, and a solution to climate change—or they can reinforce economic isolation, heighten environmental impacts, and engender social strife. They represent 80 percent of global economic output and 70 percent of total energy and greenhouse gas emissions. Cities are the superstructure for the culture, lifestyles, aspirations, and well-being of half of the world’s population today and an estimated 70 percent by 2050. If they fail and become matrixes of gridlock, poisonous air, economic segregation, and environmental pollution, the planet will follow. If they succeed in lifting the next generation into sustainable productivity, integrating immigrants and working families into the next economy and living lightly on the land, they will contribute significantly to a civilized and sustainable future.