The social cost of carbon is a central metric for optimal carbon prices. Previous literature shows that inequality significantly influences the social cost of carbon, but mostly omits heterogeneity below the national level. We present an optimal taxation model of the social cost of carbon that accounts for inequality between and within countries. We find that climate and distributional policy can generally not be separated. If only one country does not compensate low-income households for disproportionate damages, the social cost of carbon tends to increase globally. Optimal carbon prices remain roughly unchanged if national redistribution leaves inequality between households unaffected by climate change and if the utility of households is approximately logarithmic in consumption.

碳的社会成本是最佳碳价格的中心指标。先前的文献表明，不平等会严重影响碳的社会成本，但在国家层面以下大多会忽略异质性。我们提出了一种碳社会成本的最优税收模型，该模型可以解释国家之间和国家内部的不平等。我们发现，气候和分配政策通常不能分开。如果只有一个国家不为低收入家庭提供不成比例的赔偿，那么全球碳的社会成本将趋于上升。如果国家的重新分配使住户之间的不平等不受气候变化的影响，并且住户的效用在消费中大约为对数，那么最优碳价格将大致保持不变。