UN projections, which are on the "business as usual" side of things.

Plenty of events, like the pandemic, which put immense downward pressure on fertility.

Also, the African continent is a net food importer. This could be turned around - particularly by Nigeria, which has the natural resources to produce fertiliser, but so far the observed effect has been a surge (+65%) of imports.

With the situation in Ukraine being what it is, I don't think this is sustainable.

Niger is currently experiencing a population explosion, which will force it to implement the same policies as Kenya to prevent a Malthusian catastrophe.

Which means 2 centuries before we get back to 7 or 8.

I fear that a 'decent world war' nowadays may include nukes, so damage to the environment will be great. As an example, the dam that was destroyed in Ukraine and flooded a 'small area' (considering the planet-scale)(https://www.cbc.ca/news/world/kakhova-dam-ukraine-russia-1.6...).

Which (your post and my thinking of a response) reminded me of the series: Aftermath - Population Zero (https://www.imdb.com/title/tt1264068/); I remember watching some series back in the day.. I think it's time to watch this again.

EDIT: I found it on YT: https://www.youtube.com/watch?v=l11zPNb-MFg