On the other hand, there's no way China should keep its level of industrial growth and usage of fossil fuels indefinitely in the face of world threatening climate change

I agree. That's the scariest part of all of this. If any country decreases its industrial output, it decreases its ability to wage war, which means it increases its chances of getting invaded by a less principled country who continues to increase its industrial output. So all nations basically see decreasing industrial output as letting their guard down and opening themselves up to invasion. And if they get invaded/annexed by more powerful nations who don't care about the climate, their industrial output will still increase, just under a new regime imposed from the outside. So there's a global prisoners' dilemma here. I don't foresee anyone letting their guard down by decreasing industrial output. Significantly below international agreements which already aren't being followed anyway.