I think the global population will top out below 10 bn ad then will start sliding. And that is very good.
I think the global population will top out below 10 billion and then start falling quite rapidly. And it will be very ugly.
We could easily lose a few billion in the span of a few years, or worse, all of the billions. But I think a reduction of 2-3 billion due to an India-Pakistan nuclear war and resulting famine is the most likely scenario to occur and it could happen before we reach 8 billion planet-wide. This would leave most of the world at a sustainable number.
In a nuclear exchange between India and Pakistan, I could see --
About 100 nuclear weapons used
Immediate death toll (within one week) of about 100,000,000
Short-term death toll of another 500,000,000 due to fallout, war
Long-term death toll of an additional 1,000,000,000 to 2,000,000,000 due to famine and food shortages, this would occur across most developing countries
The results?
North America: population stabilized
South America: population stabilized
Europe: population growth may temporarily spike due to refugee crisis, otherwise stabilized
Africa: population would halve or worse then stabilize or continue declining
Asia: population would be reduced by a quarter or worse, then stabilize
Oceania: population stabilized