New Insights from the PAGE09 Model: The Social Cost of CO2

PAGE09 is an updated version of the PAGE2002 integrated assessment model (Hope, 2011a). Thedefault PAGE09 model gives a mean estimate of the social cost of CO2 (SCCO2) of $106 per tonne ofCO2, compared to $81 from the PAGE2002 model used in the Stern review (Stern, 2007). The mainreasons for the difference are the valuation by a representative agent from the EU, instead of theworld as a whole , which increases the mean value by a factor of 4.3, a higher range for the discountrate, which decreases the mean value by a factor of 2.7, the use of the A1B socio‐economic scenario,rather than A2, which decreases the mean value by a factor of 2.5, a higher range for the climatesensitivity, which increase the mean value by a factor of 1.5, and a lower assumption about theeffectiveness of adaptation, which increases the mean value by a factor of 1.3...