Taboo! Subtle and not-so-subtle cultural conventions keep us from considering the single most significant cause of ecological devastation: overpopulation. We’re faced with a kind of unconscious conspiracy in which folks tacitly agree not to address the earth’s swollen human population as a critical environmental issue. Even avid conservationists publicly shy away from this dead elephant in the living room. The whole host of impending ecological disasters—global warming, resource depletion and pollution, water shortages, violent conflict—are…