The problem with scenarios is that every resource is entangled with many others and that evolution of each one is wildly non-linear. Example : copper availabili

The problem with scenarios is that every resource is entangled with many others and that evolution of each one is wildly non-linear. Example : copper availability depends upon energy availability. However sustainable energy deployment depends upon copper extraction (as long as we're in the "up" part of the development S-curve). Another less important example is helium : helium is necessary for high end electronics, and electronics are necessary for modern cars. However car manufacturers are generally completely oblivious of their very real dependency upon helium, which came mostly from the US and Russia. I've just watched an interesting conference by a researcher who's working on new, complex models to build scenarios taking all these entanglements into account, managing thousands of different resources across the whole globe. At the moment there's like 5 of them working on these. Unsurprisingly, these complex, stochastic models treated with lot of Monte-Carlo analyses and now even AI are far from being stable and precise enough for projects such as IPCC. So that's where we are for now. Classical economics are wildly out of touch with reality here (Nordhaus even got the Nobel in economics with a completely bonkers linear extrapolation of climate effect on global GDP), and these sorts of interdependencies are everywhere. So OK, I've got it, the scenarios are too simple. But the IPCC working group II is composed of mainstream economists, and mainstream economists are wildly out of their league (in my opinion I'd go as far as saying that macro economy is a pseudo-science at this point anyway), so they're doing what's possible in a mainstream environment. Too bad.