They're going to say that anyway when the real cost of warming hits. Calculation about that says GDP -30% to -50%. But that's for the next legislature I guess.
Yes, for politicians the cost is always lower to kick the can into the next administration's term. Unfortunately it becomes more and more expensive for the rest of us.
It's way less than that. 2.39x10^20 is around 4% of 5.8x10^21. Not even close to "almost as much". Looks like the authors don't know their powers of 10. So if we dedicate 5% of the total energy for one year it could theoretically be done.