The other option is reducing number of humans. Whichever way we want to cut it, less mass needs to be moved less distance to meaningfully reduce consumption of fossil fuels, and that is proportional to number of humans and the distances between them.

Or the miraculous discovery of an energy / locomotion mechanism that does not have the negative side effects of current known sources.

Did densely populated areas overall fair much worse when controlling for poverty? I'm not being snarky I genuinely don't know, the last time I heard about this it wasn't conclusive.

Anyway we may have left ourselves little choice. I certainly don't think we're still within the window of "this is worse for everyone but better for me" being acceptable.

Communicable diseases spread quicker in densely populated areas, this is known.