In 2010, the U.S. government adopted its first consistent estimates of the social cost of carbon (SCC) for government-wide use in regulatory cost-benefit analysis. Here, the authors examine a number of limitations of the estimates identified in the U.S. government report and elsewhere and review recent advances that could pave the way for improvements. The authors consider in turn socio-economic scenarios, treatment of physical climate response, damage estimates, ways of incorporating risk aversion, and consistency between SCC estimates and broader climate policy.