A Model for Estimating Future Emissions of Sulfur Hexafluoride and Perfluorocarbons

Sulfur hexafluoride (SF₆), perfluoromethane (CF₄) and perfluoroethane (C₂F₆) are strong greenhouse gases with long (>1000 year) atmospheric residence times. We derive emission factors for the major anthropogenic sources and project future emissions for 5 regions and the world. Although firms in many industrialized countries are already limiting emissions, without further policy intervention global emissions will rise 150% (CF₄ and C₂F₆) and 210% (SF₆) between 1990 and 2050; radiative forcing will increase 0.026 W m^-2. Full application of available low-cost and costless policies in industrialized nations would cut that radiative forcing by one-quarter. Increased forcing due to these gases is small (<2%) relative to other gases but permanent on the timescale of human civilization. We also quantify plausible manipulations to governmental data that will be used to determine compliance with the 1997 Kyoto Protocol, which includes commitments for industrialized countries to regulate these and other greenhouse gases. More complete and transparent data are urgently needed. West European nations, for example, can cut their emissions of these gases by half by 2010 simply by manipulating emission factors within the current bounds of uncertainty.