Fun fact btw: the country with the most children per mother in the world is also the only one with a sub-20% literacy rate! (I'm not sure if I can name that country without breaking the ToS though lolololol.)
Anyway.
The population won't grow indefinitely. Current estimates say it should peak somewhere between 10 and 12 billion sometime this century and then start declining. I'm assuming this drop-off will happen when the 3rd world countries get a bit more developed.
It's a debate on whether we can effectively produce enough food for that many people though. The current model of agriculture requires a lot of external inputs (called HEIA) -- fertilisers, various modified seeds, bla bla bla. That produces a ton of food, but it's not sustainable at all. We are starting to switch into forms of agriculture that don't require that many external inputs (called LEIA) but I'm not well-informed on this subject to be honest. I'm studying this shit in uni at the moment.
As for wilderness and habitats... I honestly can't give you a good answer although I'm also studying that in university lol. However here in the West (talking EU here), the environmental conservation efforts are decent. It's also decent in USA/Canada. Even China is investing into it a lot in recent times. But for example Russia is not, at all. Hell y'all don't even have drinkable tap water in most cities.
Regarding the renewable sources, we're kind of getting there but there's a few annoying road blocks. First of all there's the skepticism towards nuclear energy in many countries. Accidents like Chernobyl or Fukushima are very rare, however because of them for example in Germany they recently closed down all of their nuclear power plants and switched back to coal and such. Which is not very good. Uranium is not a renewable resource
per se, however it is currently estimated that with the newest tech (which allows us to use the far more common uranium-238 isotope instead of just the rare U-235 one), we should have enough uranium to fuel our needs for about as long as the Earth will remain habitable. That's about 5
billion years. Conclusion: nuclear is the future!!!
That's assuming the US doesn't spend it all on bombing small countries of course!!! Sorry, had to get it out of myself.
The really unlimited resources: hydro power, wind power, solar power, tide power, also geothermal in some countries, are also being increasingly used in many countries. However it's too reliant on external factors, and also not efficient enough, to fully replace non-renewable, but if we adopt nuclear energy widely enough then I think it should be ok.
However for some things I don't really know if there's a replacement.
For example petrol/gasoline, used for transport, doesn't have a proper green alternative yet. Electric cars currently require lithium for batteries
(which is its own can of worms), and aren't really usable long-distance. Currently there is a new technology being developed, based on graphene (like graphite in your pencil, but cooler), but afaik it's not commercially available yet and who knows when it will be, especially for large things like cars.
Lastly though I wanna say that you shouldn't fret over it tooooooo much.
1) You can't do a lot about it. The most effective way to combat pollution and climate change is via adopting legislation, which is often made difficult by various lobbies of oil corporations and whatnot. This is all on a level not really accessible to most of us mere mortals.
2) humanity as a whole is quite resilient imo. I don't think we'd allow ourselves to get to the stage where we're legitimately
fucked.3) also my opinion is that the public is being guilt-tripped a lot about the extent of the current situation. There's a lot of fear-mongering and people are pushed into weird choices such as veganism, zero-waste or for example avoiding airplane travel. All of this is largely bullshit because the absolute bulk of pollution is done by industries and companies, not people.
What you can do is to follow some basic ideas:
Reduce, Reuse, Recycle and all. Don't throw trash around. Buy local if possible. Use public transport if it's possible and not too inconvenient. Bla bla bla. But don't let it "consume" you and become a part of your personality or something.
It's gonna be tough though, and in fact we are seeing the current age of abundance and limitless consumption end in front of our eyes (see: global chip shortage for instance, estimated to last at least another few years). My opinion is that, while most things will likely become less abundant in the years to come, life shouldn't change drastically.
If you're interested, look up "Shared Socioeconomic Pathways". They are models of likely developments in the future made by the United Nations while evaluating humanity's impact on the environment.
THIS IS A CLASSIC XEEP-EEP LONGPOST THAT HAS NO POINT OR EVEN ANY KIND OF STRUCTURE WHATSOEVER. AS ONE FORMER MEMBER ON HERE WOULD SAY, THANK YOU FOR TOLERATING MY SHIT.