This kind of prepping simply doesn't work except to deal with something that's over very quickly (eg: nuclear attack) because humans can't survive long-term like that. You need a community of at least hundreds in order to be a viable population. And a community that big can't isolate itself effectively.
Our choices (and they are choices) are whether we embrace rapid decarbonization together or all fail together. The outcome isn't at all certain, but we can put our thumb on the scale by exercising whatever bit of power we have to alter the politics and implementation of it.