If Steven Keen is a crackpot are there any climate scientists (or economists, for that matter) who take seriously Nordhaus’ conclusion that a 4C temperature rise would be “optimal”?

Lots of economists! He won a Nobel Prize for his work in climate economics, he is extremely credible in this area. With that being said, most do think he is a bit too conservative.

Nordhaus’ slides didn’t cite any references or give any indication of where he got his “optimal” carbon tax estimations.

His signature model is called “Dynamic Integrated Climate-Economy” or “DICE”. The code is freely available here, but you have to be comfortable running GAMS to see it. The University of Chicago did make a web version of it, but I don’t know if it’s up to date anymore. If you’re more interested in the literature behind the model, he has published many papers on it.

We should be focusing “decarbonization pricing”, not carbon pricing.

I still don’t see any meaningful difference though. Social Cost of Carbon would still achieve the same end, and it at least gives us a framework for how fast it should occur.