In February, the U.S. District Court for the Western District of Louisiana issued a sweeping and widely-criticized injunction prohibiting federal agencies from applying the social cost of greenhouse gases estimates developed by the Interagency Working Group, and further prohibiting the Working Group from updating those estimates. The U.S. Court of Appeals for the Fifth Circuit has since stayed the injunction, but the litigation remains ongoing as the appeals court receives full briefing from the parties.
In this amicus brief, we explain how the Interagency Working Group based its climate-damage valuations on voluminous and expert science, and that its approach followed regulatory guidance and precedent. In particular, the brief supports the Working Group's selection of discount rates and geographic scope, explaining how those choices followed expert consensus and were consistent with agency treatment of other regulatory impacts.