Thanks for pointing out the energy density of fossil fuel (12x batteries, 3x hydrogen, etc), which make it hard to replace for things like semis, jets, missiles, tanks. That said, there is some hope:

1) World populations are expected to decline

2) Current trajectory perhaps 50/50 renewable/fossil fuel by 2050, 90/10 renew./f.f. by 2100? Not what should happen but probably will. People don't realize the difficulty of phasing out things like natural gas, given growing electricity demands and slow-growing renewable infrastructure.

3) As such, some level of warming inevitable, will we relocate and adapt? I would think so, unless we destroy ourselves in wars first.

4) Habitat encroachment could tip too many dominos, yet Roman Empire created major encroachment, some recovery from 500 to 1500 AD. Will there be a coming Dark Age that allows recovery from our current resource orgy?