> You didn't mention why this transition isn't possible. There is also not enough green energy currently to stop using fossil fuels. It is either transition or death.
Nope: I mean that green energy is just not capable of replacing fossil fuels, just by looking at orders of magnitude. Thinking that it is possible by extrapolating some graphs is just naive. It is not, that's all.
Of course we need to build alternatives (both nuclear plants and renewables), but they will only cover a fraction of fossil fuels. Don't under-estimate fossil fuels, they are extremely efficient energy.
> To use much less energy, we would need to give up cars, trains, AC, and heat. [...] We might have to give up food
That's the whole point of degrowth: prioritize what you can keep. Planes will mostly disappear, that's pretty much a fact. Food has to stay under some form, quite obviously (but meat will mostly disappear).
We are at a point where it is about survival: we need to organize our society and cities such that people don't starve in the next few decades. Let's be optimistic, I believe we can still keep a modern society. But probably we won't change smartphone every year, and people living in cities won't own a car.