I would expect economic development to gradually cause a decline in birth rates? Is there a GDP marker where delta GDP > delta population?

As far as overpopulation, the entire continent of Africa has roughly the same population (1.3b) as India with ~9x the land area so the absolute population density is not dire.

2. If you look at carbon emissions per capita, African countries are relatively carbon neutral. Ethiopia relies mostly on renewable energy and they are also building the largest hydroelectric power plant on the continent. I would expect younger economies to “leap frog” to cleaner and greener tech, having polluted less in total (than countries before them) by the time they attain middle income status.