Social Costs of Methane and Carbon Dioxide in a Tipping Climate

Social costs for methane and carbon dioxide emissions, from the risk of climate tipping events and deterministic damages, are derived in an analytically tractable model. In the core model: social costs from tipping risks rise with income, just as they do for deterministic damages, and depend on only a few parameters. Consequently, methane’s weight (its social cost relative to carbon dioxide) is constant and independent of temperature projections. But other damage and tipping probability formulations assumed in the literature imply methane’s weight varies over time and with temperature projections. (JEL H23, O44, Q40, Q54, Q56, Q58).