🧵Good news and bad news on the Biden Administration's efforts to consider a "social cost of carbon" via an Interagency Working Group on the Social Cost of Greenhouse Gases
https://www.whitehouse.gov/briefing-room/presidential-actions/2021/01/20/executive-order-protecting-public-health-and-environment-and-restoring-science-to-tackle-climate-crisis/
Good news
The IWG is (apparently, for now) employing a methodology that does not use the RCPs or SSPs
https://www.nap.edu/catalog/24651/valuing-climate-damages-updating-estimation-of-the-social-cost-of
Bad news
The methodology of the IWG employs scenarios that are more out-of-date than the RCPs/SSPs -- selected from the EMF-22 scenarios
https://www.nap.edu/catalog/24651/valuing-climate-damages-updating-estimation-of-the-social-cost-of
Just compare 2100 global CO2 emissions of EMF-22 baseline scenarios (L below) used by the IWG with recent (LR21) projections of the same (R below)

SCC estimates are based on median 2100 CO2 >2x of most recent projections, rendering derived damage functions immediately obsolete
PS. Energy and climate experts will have a good chuckle at this extension to 2300 (which, yes, is absolutely central to SCC estimates) @jritch
PPS. To be clear, I don't know (and neither do you) whether an updated use of scenarios in constructing a SCC would result in a larger or smaller value

Lots of moving parts in scenarios, crucially: GDP & damage

Be we all should agree that using out-of-date inputs in no bueno
You can follow @RogerPielkeJr.
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