People don't talk about this as a viable way to combat climate change because even with the amount of people living on the planet right now we are already vastly overusing the resources the earth can provide for us. First world countries use a huge amount more resources than developing nations even when they have a much smaller population than them.
The only way to combat climate change at this point is to have people in developed nations consume less and lead more sustainable lives while putting money and legislation in effect to make sure developing nations industrialize with sustaible energy to lessen their environmental impact as they grow.
Yes, this is true. And going by this exact logic, it is a hilariously misguided to think that carbon equivalent emmisions will some how subside with a world population leveling out at 12 billion people because that inevitably implies all of them will prioritize standard of living and modern conveniences over subsistence living. It is actually the people with fewer kids in highly developed nations doing all the polluting.
This is the paradox we will have to mitigate via technology and good policy decisions.
I will give you a recipe for winning this battle:
-sustainable power sources such as next gen nuclear and renewables
-electric vehicles leveraging advanced battery technologies for extended range and fast charging times and/or internal combustion engine cars fueled with net zero emission plant based fuels like methanol, ethanol, or bio diesel
-fix the farm bill to remove subsidies for livestock and livestock feed crops, making meat and dairy much more expensive (reflective of actual cost to produce)
-provide financial incentives for people to only have 2 or less children