which represents the relative change in welfare as changes from 0to and the stock of pollution isP.In order to determine the value of 0we use the following 2008 data. We use $60,689.812 billionas the value of the world GDP in 2008, as reported by the World Economic Outlook (2009) of theInternational Monetary Fund. We use 9.9 ± 0.9GtC as the value of total CO2emission from fossil fuelcombustion and land use change in 2008, as reported by Le Quéré et al. (2009). We use a short-termdecay rate of emissions of 36% (i.e. 64% of emissions adds to the stock in any given year), as reportedby Newell and Pizer (2003). Also, 3.67 represents the conversion rate from units of carbon to units ofCO2. Using these values, we obtain