1. Rapid change of any kind is bad in any ecosystem. Growing the population too fast creates one set of problems, shrinking the population too fast creates a different set of problems.
2. modern humans have the ability to expand consumption to use all available resources. 10 million jet-setting billionaires have a far worse impact on the environment than 1 billion poor people. Adjusting the environmental impact per human is going to have a far greater effect on the environment, and more quickly, than population changes.
And you are right - but poor people _want_ to have material luxuries, by and large, so we should consider what we want our equilibrium state to look like.
Personally, I'm hoping for "8-10 billion people eating low meat diets, living in well insulated homes powered by renewable electricity, in places where they can walk, bike, or take public transport for almost all of their daily needs, and working a 20 hour (or less) week, with the remainder of their time filled with their friends, families, creative passions, and any other joys not yet comprehended"
but it doesn't seem like that's where we're headed.
> Why? (I speak as someone who fits that description and has kids)
I’m not the original commenter, but I assume that the reference is that this/your group fairly reliably across most cultures does not maintain the 2.1 children per woman birth rate / replacement rate needed to sustain a population.
At a minimum, this seems to be true for this particular socioeconomic class in most parts of Europe, East Asia, and US/Canada. Not sure about South Asia.
1. Rapid change of any kind is bad in any ecosystem. Growing the population too fast creates one set of problems, shrinking the population too fast creates a different set of problems.
2. modern humans have the ability to expand consumption to use all available resources. 10 million jet-setting billionaires have a far worse impact on the environment than 1 billion poor people. Adjusting the environmental impact per human is going to have a far greater effect on the environment, and more quickly, than population changes.