The earth has had higher CO2 levels… and had much more biodiversity when it did. If anything for a sustainable world for life we should probably be targeting the 800ppm of the Carboniferous and not the 200ppm of the little ice age.

Can you tell me why from a sustainability perspective why 200ppm is the ideal? Or if 200ppm is not the ideal what is the sustainable ideal, and why civilization collapses if we don’t reach that target?

I mean the totality of civilization not just that Buckingham palace or a few other places might be underwater? Like why can’t we build ports a little inland from Amsterdam? Why can Paraguayans survive 40C but civilization collapses if Europe goes above 27C.