[영문]How much and how fast should the globe reduce greenhouse-gas emissions? How should nations balance the costs of the reductions against the damages and dangers of climate change? This question has been addressed by the recent qqqquot;Stern Review on the Economics of Climate Change,qqqquot; which answers these questions clearly and unambiguously. We need urgent, sharp, and immediate reductions in greenhouse-gas emissions. An analysis of the qqqquot;Stern Reviewqqqquot; finds that these recommendations depend decisively on the assumption of a near-zero social discount rate. The Review's unambiguous conclusions about the need for extreme immediate action will not survive the substitution of discounting assumptions that are consistent with today's market place.