Roger Cooke:Twin RFF SEJ panels supporting Social Cost of Carbon

RFF empanelled 20 top economists to quantify uncertainty in key parameters of the updated Social Cost of Carbon computing platform. One panel was concerned with CO2 equivalent emissions out to 2300 while the other focused on GDP per capita, also out to 2300. Each panel answered 11 (different) calibration questions. Population projections out to 2300 were made by Adrian Raftery’s group based on a UN sanctioned methodology. Many interesting issues were raised in building a joint distribution over these time series. This talk is focused on the SEJ elicitations. The economists returned very good performance. Over all studies about 33% of the experts have a statistical accuracy score above 0.01, in these panels this was 47%.  Equal weight and performance weight decision makers showed the familiar pattern; both were statistically accurate with performance weighting being 70% (52%) more informative for GDP (CO2). Persistence of experts’ performance was measured by testing the Hypothesis that expert performance differences are due to chance fluctuations. This hypothesis was rejected for both panels with the strongest rejection emerging from panel minima. That is, the worst performing expert was statistically distinct from worst performers in a large sample of scrambled panels in which assessments are randomly re-allocated to experts.  This is the most interesting aspect for the SEJ group IMO and will explained in detail and hopefully to everyone’s satisfaction. The median assessment for the social cost of carbon comes in at about 4 times the current value; these will be presented if the submission is no longer embargoed.

Rennert, Kevin, Prest, Brian, Pizer, William, Newell, Richard, Anthoff, David, Kingdon, Cora,  Rennels, Lisa, Cooke, Roger, Raftery, Adrian E.  Ševčíková, Hana and Errickson, Frank (2021) The Social Cost of Carbon: Advances in Long-Term Probabilistic Projections of Population, GDP, Emissions, and Discount Rates with online appendix, Brookings Papers on Economic Activity Working Paper (21-28) Sept 9, 2021.

Rennert, Kevin, Frank Errickson, Brian C. Prest, Lisa Rennels, Richard G. Newell,  William Pizer,  Cora Kingdon, Jordan Wingenroth, Roger Cooke,   Bryan Parthum,  David Smith,  Kevin Cromar,  Delavane Diaz, Frances Moore,  Ulrich K. Müller, Richard Plevin,  Adrian E. Raftery, Hana Ševčíková,  Hannah Sheets,  James H. Stock, Tammy Tan, Mark Watson, Tony Wong, David Anthoff , (2022) New Scientific and Economic Evidence Suggests a Higher Social Cost of CO2 submitted to NATURE