Federal agencies need to pick estimates of social cost of greenhouse gases that best promote the interests and fulfill the responsibilities of the United States. But debate has reemerged about whether federal agencies’ policy analyses should focus on those climate pollution costs that will occur only within U.S. borders, rather than on the full global valuation of climate damages. The Interagency Working Group on the Social Cost of Greenhouse Gases provides compelling justifications to focus on global estimates.
Based on a wide range available evidence, the Working Group should consider recommending a domestic valuation of at least 75% or more of the global values for optional use as a lower-bound estimate in sensitivity analysis. Bearing in mind both that the global estimate itself is likely an underestimate, and also that the scientific and economic understanding of inter-regional impacts is still developing, the Working Group should clarify that such domestic estimates remain provisional lower-bounds and may underestimate even the minimum strategic value to U.S. interests of addressing global climate change.