I think one idea you're thinking about is the idea of Social reproduction. [1] Warning it's a Marxist idea, so if that's just going to upset you, just skip the rest of this. But the core thought is that for people to continue civilization, there are a number of areas that just need support from financial, cultural, social and human areas. It maybe needs some refreshing to more explicitly add tech and environmental areas - but really they're covered under those categories.
While the eco side effects of reduced population pressure are beneficial, they are unintentional, while still letting all sorts of other industrial & financial processes continue to put pressure on problems like climate change. Reduced fertility can be bad from a social reproduction standpoint if poor financial and social conditions are what's driving down the rate. It drives all sorts of other economic and social problems (see Japan for a foreshadowing of this).
Still, reduced population is something we have to work through anyway if we want to make it easier to live at a sustainable level of human civilization on the Earth.
While the eco side effects of reduced population pressure are beneficial, they are unintentional, while still letting all sorts of other industrial & financial processes continue to put pressure on problems like climate change. Reduced fertility can be bad from a social reproduction standpoint if poor financial and social conditions are what's driving down the rate. It drives all sorts of other economic and social problems (see Japan for a foreshadowing of this).
Still, reduced population is something we have to work through anyway if we want to make it easier to live at a sustainable level of human civilization on the Earth.
[1] https://en.wikipedia.org/wiki/Social_reproduction