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On February 26, 2021, the US government’s Interagency Working Group on the Social Cost of Greenhouse Gases (IWG) issued the Technical Support Document: Social Cost of Carbon, Methane, and Nitrous Oxide Interim Estimates under Executive Order 13990 (EO 13990). This support document provides interim estimates of the social cost of carbon (SC-CO2), social cost of methane (SC-CH4), and social cost of nitrous oxide (SC-N2O), collectively called the social cost of greenhouse gases (SC-GHG). The provision of the interim estimates is one step in the federal government’s process that will culminate in the issuance of final SC-GHG estimates in early 2022 as required by EO 13990.
EO 13990 directs that the federal government’s update of the SC-GHG adhere to the recommendations laid out in a landmark report issued in 2017 by the National Academies of Sciences, Engineering, and Medicine (hereafter NASEM), Valuing Climate Damages: Updating Estimation of the Social Cost of Carbon Dioxide, conducted in response to a study request in 2015 from the IWG. The NASEM panel conducted a comprehensive evaluation of potential updates to the SC-CO2 estimation methodology and put forward a number of conclusions and recommendations on how to improve the conceptual underpinnings, empirical methods, and data used to calculate the SC-CO2, as well as the transparency and flexibility of the process by which future estimates are generated (NASEM 2017). The conclusions and recommendations of the NASEM report focus primarily on the calculation of the social costs resulting from the emissions of carbon dioxide, but they are also broadly applicable to the social costs of other greenhouse gases such as methane, nitrous oxide, and hydrofluorocarbons. The report provided both near-term recommendations that were designed to be implementable within two to three years and recommendations for longer-term improvements to the methodology.
The Social Cost of Carbon initiative was established in 2017 as a multi-institutional, collaborative effort between Resources for the Future (RFF) and the University of California–Berkeley, with additional contributors from Duke University, Harvard University, Princeton University, and the University of Washington, among others. The initiative has the following key objectives:
- improve the scientific basis for SC-CO2 estimates by implementing the full set of near-term recommendations from the 2017 NASEM study and provide a transparently updated SC-CO2 with uncertainty bounds
- develop open-source software tools for SC-GHG estimation to implement updated methods, promote transparency, and serve as a common platform for SC-GHG development by the scientific community
- facilitate the US government process to update values for SC-GHGs
In this comment, we discuss RFF’s implementation of the NASEM report’s near-term recommendations. We follow the report’s organizational structure and include the committee’s full set of recommendations for completeness. However, some of the recommendations fall outside the scope of the federal government’s activities underway to establish a near-term update of the SC-GHG estimates as well as our current research activities. Though we focus on RFF and its direct collaborators’ research efforts in this comment, we note the numerous additional and significant research contributions of relevance to the IWG’s near-term update of the SCC estimates that have been put forward in recent years that will be the subject of separate comments by their respective authors.