I’d be curious to know where you get the figures to say that “most of the problem — a little over US$ 1 trillion — is the failure to properly price carbon pollution.”

If you look at Appendix Table 1, you will see that the IMF’s reference Pigouvian tax is comprised of a whole lot of other externalities, including even traffic congestion (a problem that is not efficiently addressed through a tax on fuel, as congestion varies over time, and even electric vehicles contribute to it). In the case of transport fuels, their carbon tax component accounts for at most 1/6 of their optimal tax. Note in the discussion of coal, local pollutants also weigh heavily in their accounting for externalities.

So a more accurate description would be “most of the problem — a little over US$ 1 trillion — is the failure to properly price externalities associated with fossil-fuel combustion and the operation of motorized vehicles.”