That's the Summary.
Did you buy the book so that you could validate their claims?
You missed this bit - the part that details uncertainties & assumptions;
"This paper estimates fossil fuel subsidies and the economic and environmental benefits from reforming them, focusing mostly on a broad notion of subsidies arising when consumer prices are below supply costs plus environmental costs and general consumption taxes."
Remember, transition to increased renewables is applicable WHEN it is socially & economically viable.
