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An efficient climate policy is based on cost-benefit analysis (CBA) and equates marginal abatement costs across all forcing agents affecting climate change. In CBA, the agents' contributions to radiative forcing (RF) must be consistently priced (i.e. the social cost of RF, occurring at a specific time, must be the same regardless of the agent causing it). We present a concept that enables doing so. The Social Cost of Forcing (SCF) is the monetary value of the social damage caused by marginal RF at a given instant (Wm − 2 ). Any forcing agent whose temporal decay profile and radiative efficiency are known can be priced based on it. Prices obtained for distinct agents are consistent in CBA, as long as the same SCF and discounting assumptions are applied. Hence, the SCF is a concise way to communicate social cost information: mutually consistent prices for any set of forcing agents can be obtained based on a single Integrated Assessment Model output, the SCF. We explain the theoretical foundations of the concept and illustrate its practical applications with two examples: (1) we derive SCF-based prices for CO 2 and CH 4 , and (2) we estimate the social cost of albedo changes in a boreal forest stand. [ABSTRACT FROM AUTHOR]

Analyzing land-based climate mitigation measures requires the joint examination of the effects of multiple forcing agents. Non-CO 2 forcing agents are often converted into "physical" CO 2 equivalents, i.e., expressed in terms of how much CO 2 would be required to inflict the same climate forcing as one unit of the agent. Similar conversions can also be based on equal social cost. Social-cost-based CO 2 equivalents are ideal for economic applications, as they retain the correct social cost ratio between forcing agents. We present two kinds of social-cost-based CO 2 equivalents for albedo-induced (or any other transient) forcing. The emission equivalent expresses transient forcing as equivalent CO 2 emissions (tCO 2 yr −1). The stock equivalent expresses it as an equivalent reduction in the terrestrial carbon stock (tCO 2). We compare physical and social-cost-based CO 2 equivalents, showing that social-cost-based the emission equivalent is a generalization of its physical counterpart, whereas social-cost-based stock equivalent is not. Nevertheless, the two stock equivalents are structurally similar and of roughly the same magnitude. We discuss how the equivalents can be applied in economic analysis, provide numerical multiplier values for converting transient forcing into emission and stock equivalents, and assess the extent to which physical CO 2 equivalents distort the social valuation of transient forcing. • Transient albedo-induced radiative forcing can be converted into CO 2 equivalents. • The CO 2 emissions equivalent depicts transient forcing as equal CO 2 emissions. • The CO 2 stock equivalent depicts it as a reduction in the stock of stored CO 2. • Both equivalents may be based on equal physical forcing impacts or equal social cost. • The social-cost-based CO 2 equivalents are ideal for economic applications. [ABSTRACT FROM AUTHOR]