The social cost of atmospheric release

The author presents a multi-impact economic valuation framework called the Social Cost of Atmospheric Release (SCAR) that extends the Social Cost of Carbon (SCC) used previously for carbon dioxide (CO2) to a broader range of pollutants and impacts. Values consistently incorporate health and agricultural impacts of air quality along with climate damages. The latter include damages associated with aerosol-induced hydrologic cycle changes that lead to net climate benefits when reducing cooling aerosols. Evaluating a 1% reduction in current global emissions, benefits with a high discount rate are greatest for reductions of sulfur dioxide (SO2), followed by co-emitted products of incomplete combustion (PIC) and then CO2 and methane. With a low discount rate, benefits are greatest for CO2 reductions, and are nearly equal to the total from SO2, PIC and methane. These results suggest that efforts to mitigate atmosphere-related environmental damages should target a broad set of emissions including CO2, methane and aerosols. Illustrative calculations indicate environmental damages are $150-510 billion per year for current US electricity generation (~6-20¢ per kWh for coal, ~2-11¢ for gas) and $0.73±0.34 per gallon of gasoline ($1.20±0.70 per gallon for diesel). These results suggest that total atmosphere-related environmental damages plus generation costs are greater for coal-fired power than other sources, and damages associated with gasoline vehicles exceed those for electric vehicles.