Thread by @RogerPielkeJr

🧵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
whitehouse.gov/briefing-room/…

Good news
The IWG is (apparently, for now) employing a methodology that does not use the RCPs or SSPs
nap.edu/catalog/24651/…

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The methodology of the IWG employs scenarios that are more out-of-date than the RCPs/SSPs -- selected from the EMF-22 scenarios
nap.edu/catalog/24651/…

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

Sources:
EMF-22 used in IWG SCC: epri.com/research/produ…
LR21: nature.com/articles/s4324…

This thread is a placeholder for a future discussion

The IWG is expected to produce its 1st report with interim estimates in about 10 days

The use of scenarios in SCC estimates will be an early, important test of scientific integrity under Biden

/END
resourcesmag.org/common-resourc…

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Be we all should agree that using out-of-date inputs in no bueno