[_3u10]

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.

[throwaway15908]

>Why are 200ppm sustainable?

The higher CO2 levels of long gone times where probably not even remotely a problem for those critters around, because evolution had plenty of time to do its thing. Your whole point of "but what about back then" is comparing apples with oranges.

Looking at the steep graph today, the increasing weather extremes and how brittle our supply chains are, i think its very appropriate to call it a climate catastrophe, we are heading for.

Btw. I was using the ideal of perfect recycling and applied it to CO2, no absolute or relative ppm value is relevant for this.