The social cost of carbon (SCC) is defined as the cost of the damages created by one extra ton of carbon dioxide emissions. According to some, it is the single most important number that nobody has heard about. The social cost of carbon is used to help policy makers determine whether the costs and benefits of a proposed policy to curb climate change are justified. In this conversation Richard Newell will discuss how social cost of carbon is calculated, how it is used, and the difference between SCC and the carbon price companies are using to evaluate investments.