This amazing video by a mathematician/demographer Hans Rosling shows how Earth’s human population will stabilize at 11 billion. The math is complicated, but he makes it beautifully simple and compelling. Barring nuclear war, this is how it will play out:
One of the reasons that domestic issues figure so prominently in the Green New Deal is that people with a good standard of living have fewer children, with many modern countries now failing to even reach replacement birth rates.
Our world is much smaller now in travel time than were the original 13 American states, from Maine to Georgia, in the 18th century, so clearly, war should have become taboo many years ago. I believe it did become taboo the moment the first atom bomb was detonated in White Sands, New Mexico, but only in the minds of civilized humans. If humans can work together worldwide and put war behind us, as have the formerly blood-soaked countries of the European Union, we can work towards amazing engineering solutions to all human problems, even for 11 billion humans.
Multi-story hydroponic farms, clean energy, alternative dwellings, careful stewardship of our resources, and fair income, healthcare, and education for all citizens of Earth would mean that our world could sustain a population of 10 or 11 billion. After just a very few generations in an enlightened, peaceful world, population would probably ratchet down to an even more sustainable level.