Estimation of the greenhouse gas externality with uncertainty

The shadow price of carbon dioxide is the value of the external damage caused by an emission. A shadow price model for calculating the present value of the external damage of a carbon dioxide emission is derived explicitly. Sixteen experts provided subjective high, low and most likely parameter estimates because correct values for the eight model parameters are uncertain. The estimation procedure retains parameter uncertainty while generating the main result, which is a distribution of shadow price estimates. Major assumptions made in the estimation identify the basis for the results. Of the eight model parameters, the discount rate dominates the determination of the shadow price. For comparison, expert estimates of the shadow price itself provide a second distribution of shadow price estimates.