A collapse of western 21st century civilization to a hunter-gatherer system means massive die-off of humans. There's never been enough natural food to support our population booms.

A hunter-gatherer-based system presumes a healthy ecosystem that will support the production of edible animals and plants. With accelerating climate change, all bets on the future are off.

I do not think climate change will reach the level of say Venusian climate, mostly from co2 having been really high with plant life and everything here on Earth.

Assuming die-off to hunter-gatherer level of population I would predict that those who survives are predominantly those already living as hunter-gatherers, in particular those that live in (oil-free) deserts and other very inhospitable climates.

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