Choices in the climate commons

Abstract

Climate change is a tragedy of the commons of existential importance. At the annual United Nations climate summit that concludes this week, parties will affirm the necessity to avoid dangerous climate change. But between now and next year's summit, these same countries will in many ways act so as to hasten the outcome that they say must be avoided. This disjunction between what countries say and what they do has been repeated every year since the first summit in 1995. It is a pattern of behavior that seems irrational, but that can be explained. American ecologist Garrett Hardin's classic article, “The Tragedy of the Commons,” published in Science 50 years ago this week, vividly describes the dilemma that causes this behavior (see page 1236).