Economists have adopted the Pigouvian approach to climate policy, which sets the carbon price to the social cost of carbon. We adjust this carbon price for macroeconomic uncertainty and disasters by deriving the risk-adjusted discount rate. We highlight ethics- versus market-based calibrations and discuss the effects of a falling term structure of the discount rate. Given the wide range of estimates used for marginal damages and the discount rate, it is unsurprising that negotiators and policy makers have rejected the Pigouvian approach and adopted a more pragmatic approach based on a temperature cap. The corresponding cap on cumulative emissions is lower if risk tolerance and temperature sensitivity are more uncertain. The carbon price then grows much faster than under the Pigouvian approach and discuss how this rate of growth is adjusted by economic and abatement cost risks. We then analyse how policy uncertainty and technological breakthrough can lead to the risk of stranded assets. Finally, we discuss various obstacles to successful carbon pricing.

经济学家对气候政策采用庇古方法，将碳价格设定为碳的社会成本。我们通过推导出风险调整后的贴现率来针对宏观经济的不确定性和灾害调整碳价格。我们强调基于道德与基于市场的校准，并讨论贴现率期限结构下降的影响。鉴于用于边际损失和贴现率的估计范围很广，谈判者和决策者拒绝庇古方法并采用基于温度上限的更务实的方法也就不足为奇了。如果风险承受能力和温度敏感性更加不确定，则相应的累积排放上限较低。然后碳价格的增长速度远快于庇古方法，并讨论如何根据经济和减排成本风险调整这种增长速度。然后分析政策不确定性和技术突破如何导致资产搁浅风险。最后，我们讨论了碳定价成功的各种障碍。