Thread by @hausfath

Hi Roger, while I agree that the new, more realistic scenarios adopted by the ECB are laudable, I do have some small qualms with your @FT op-ed.

1/4

https://twitter.com/RogerPielkeJr/status/1401940374470291458

First, you suggest that our @Nature paper says "fossil fuel emissions would be about 25 Gt by 2100, under assumed 2019 policies and technologies." We argue that current policies (as reflected by the 2019 @IEA WEO) implied around 3C warming (similar to SSP2-4.5 or SSP4-6.0). 2/4

We did not, however, imply that the particular emission pathways in SSP2-4.5 or SSP4-6.0, which are characterized by near-term emission increases or late-century emissions declines are implied by current policies. Flat emissions are arguably more consistent, but who knows! 3/4

Second, I'm really not sure where your "the hothouse scenario projects 81 Gt, over three times as much" line comes from. The new scenarios range from 28 GtCO2 to 73 GtCO2 in 2100 under current policies (GCAM, which is the one they tend to highlight, is at ~52 GtCO2). 4/4

Note that Roger was referring to the old 1.0 models, which did indeed reach 81 GtCO2 by 2100, so my criticism here was inaccurate. Sorry about that!