If we accept that the world's population cannot grow indefinitely (and nature would never allow this), what then, is the optimal population, that would achieve a much better balance between human welfare (which is still atrocious for half or more of the world's citizens) and the planet's ecology (going to hell right before our eyes)?
I am going to say: something like 2 billion people at most. With at least 2/3 of the planet more or less off limits to resource exploitation; reserved for flora and fauna. With most of the 2 billion living in dense megacities (not sprawlsburgeria).