“There are too many people in the world, and too many more are on the way. This is an issue that, in the United States, both conservatives and liberals have often seemed eager to avoid--for conservatives, perhaps, because it raises questions about family size, birth control, and abortion, and for liberals because it raises questions about immigration. Every one of the world's environmental problems is made worse by increases in the number of humans, and, most of all, by increases in the number of Americans, since U.S. residents--whether manufactured locally or imported from abroad--have the largest energy and carbon footprints in the world.”