You wrote:
Of course, it would be churlish to mention that much hinges on that very subjective word "need," so they've given themselves an out right off the bat. Even the apparent quantitative 80% has enough wiggle room to slip a truck through, since "80% of what," well, that remains an open question -- global energy supply could (there's that word again) amount to not very much at all, compared to what we're used to, somewhere in the neighborhood of 450 exajoules per year.
If they are implying that we'll have enough windmills, solar panels, etc. to produce 360 EJ per year within 40 years, I suggest it's an extraordinary claim that calls for extraordinary proof. Presumably, somewhere down in that 1000 pages it's ready for inspection -- what Maryland-sized pieces of territory to pave with solar panels, what coastlines to take over with wind farms, what volcanoes and geysers to spigot, what factories to repurpose for the effort, what banks are willing to float bonds the size of Europe's GDP, and what armies of workers are likely to be marshaled for a construction enterprise that would dwarf not just the Manhattan Project, but all of World War II -- by a couple of orders of magnitude.
This just doesn't scale up that cheerfully.
Meaningless criticisms:
- Claiming that the demand figures are subjective. All future forecasts are tot some extent "subjective". The question isn't whether they are subjective, the legitimate questions for public policy discussion is whether they are the most accurate projection that we can produce with available data and techniques, and what the goal of the entity doing the analysis is.
Given this is a very comprehensive report by the IPCC, it's absurd to claim the demand projection undermines the report.
- The report is both a technical analysis and a policy recommendation document. It doesn't say we "WILL" - that is you using a red herring. What it says is that 'we can if we implement the appropriate policies'. It also says that those policies are NOT a burdensome drain on society.
- The implicit core of your statement related to the amount of energy needed is that the job is too big to accomplish with renewables in the time frame given. That is completely false and the items on your list of points you think of as substantiating your claim is straight out of the right wing think-tank industry. They are demonstrably nothing more than irrelevant sound-bites.
I don't give a fig what your world view is or whether you are optimistic or pessimistic about our ability to deal with the problems of modern culture, but I do care about maintaining an accurate representation of the technical abilities and processes involved with responding to one specific problem - climate change.
If you are going to trot out mythological bullshit about those topics you can expect me to respond vigorously when I see it.
If you want to try to defend the specifics of any of the list you gave and show how the IPCC got it wrong or was being overly optimistic I invite you to present the evidence for discussion. Half-baked, unsupported right wing talking points not allowed.