Perri-air!
Brilliant!
I don't see why we can't have both a far larger human population and a far more pristine environment.
...Though let's remember that nature can be a real bitch - natural disasters kill senselessly thousands of people, and there is no peaceful coexistence between predator and prey.
But I digress. Roddenberry wrote of cities underground and we saw one version in VOY's premier. Above ground, there could be immense structures soaring into the empty sky or floating on water that could house similarly immense populations - ones that today are spread over hundreds or thousands of square miles.
Regarding waste, if they recycle every molecule on a starship, surely they could apply some of that technology to make a population five times the size of ours produce one thousandth the waste. Same with energy - a few anti-matter reactors in orbit (for safety's sake) could do the trick.
Heat's a little trickier. Especially since I'd like to see MORE plants and animals...including from other worlds, times in history (dinosaurs) and entirely artificial ones flourishing alongside more humans and alien immigrants. All coexisting in a balanced, resilient, evolving ecosphere. But I'm sure there are ways around that as well. Ways to block some of the sun's heat, or moving slightly adjusting the planet's orbit, or releasing some of the Earth's geothermal energy into space - or exporting it?
Don't get me wrong...I don't think we should get started on any of this till it's technologically reasonable to do so, but let's not throw this fantastical future out with the bathwater because the real present is in bad enough a state. This is one of the reasons I love Star Trek especially in the realm of science fiction - it explores the possibilities for good as well as just ill.

I don't see why we can't have both a far larger human population and a far more pristine environment.
...Though let's remember that nature can be a real bitch - natural disasters kill senselessly thousands of people, and there is no peaceful coexistence between predator and prey.
But I digress. Roddenberry wrote of cities underground and we saw one version in VOY's premier. Above ground, there could be immense structures soaring into the empty sky or floating on water that could house similarly immense populations - ones that today are spread over hundreds or thousands of square miles.
Regarding waste, if they recycle every molecule on a starship, surely they could apply some of that technology to make a population five times the size of ours produce one thousandth the waste. Same with energy - a few anti-matter reactors in orbit (for safety's sake) could do the trick.
Heat's a little trickier. Especially since I'd like to see MORE plants and animals...including from other worlds, times in history (dinosaurs) and entirely artificial ones flourishing alongside more humans and alien immigrants. All coexisting in a balanced, resilient, evolving ecosphere. But I'm sure there are ways around that as well. Ways to block some of the sun's heat, or moving slightly adjusting the planet's orbit, or releasing some of the Earth's geothermal energy into space - or exporting it?
Don't get me wrong...I don't think we should get started on any of this till it's technologically reasonable to do so, but let's not throw this fantastical future out with the bathwater because the real present is in bad enough a state. This is one of the reasons I love Star Trek especially in the realm of science fiction - it explores the possibilities for good as well as just ill.