Someone please tell me it'll be okay.
Yes and no. Lots of people don't like anyone at their high school, don't concern yourself. It is after all a random group of people placed together based on geographical location and age, neither of which you get to choose. There's no reason you should find anyone whose company you really like. As for the potential thing, you're really young. You might feel like you should know exactly what to do with your life by the time you leave high school but that's not true, you've got decades and decades ahead of you to work that out.
It's also worth considering the possible awesomeness of the post-apocalyptic sci-fi future. Seriously, it could be brilliant. Just imagine, a clean slate to start again but with mutant biker gangs and clothes made out of car tires. However, you're utterly wrong about not being able to do anything about environmental damage. All it takes is for people to be bothered to do something and you clearly are bothered, so that's great. You'll probably feel less powerless as you get older and find more opportunities to actually take action. Admittedly maybe not a lot less powerless but it really is possible.
So basically, you're right to worry about the future and that the world is pretty fucked but it doesn't have to be. And this thread really should be made into the blog thread.