This is complicated, and ultimately you're the only one who can make this call for your life, but here's a few observations that I wasn't thinking of when I was in high school asking myself this question and have only become apparent through experience:
1. Don't forget that there are other people out there! It's possible for a problem to be important, for many people to be working on it, but for your honest assessment to be "I'd just get in the way, because I have neither the talent nor drive to effectively contribute to solving the problem." That's fine - go work on problems that you can contribute to, and through the wonders of our market economy, you end up making life easier for the people who are working on the problem. There's a strong argument for thinking in relative terms when deciding what problems to work on, i.e. "What can I most contribute that other people can't?" rather than simply "What can I most contribute?" or "What most needs doing?"
2. Young people - particularly young people who are really good at rational & logical thought - tend to underweight their emotions when deciding what to work with. You're going to be stuck with them throughout all of the actual work, so it's very difficult to be effective at problem solving when you don't actually enjoy the problem solving.
3. Many really big problems got that way because they're effectively unsolvable. When I was a teenager, the biggest problem facing earth was arguably climate change, which is arguably still the biggest problem. In the 15 years between my HS graduation and the Paris Accords, we made negative progress toward solving this, and then a year after the Paris Accords we reversed all the progress we'd made. Now, the best science available shows that it's effectively too late, we're screwed, and we should focus on harm-mitigation. Everybody knew it was a problem in the 1990s and even the 1980s, but fixing the problem required cooperation from powerful entities that had every interest in not fixing the problem, and that sort of cooperation is basically impossible to achieve. While big ideas like this sound great and get people fired up, you usually accomplish more by working on small problems with no opposition and then putting yourself in a position where you can solve the big problem without the consent of all the people who caused it in the first place.
4. Realistically, small problems are much easier to solve than big problems, and solving a bunch of small problems (like, say, "How can Uber or similar competitor reduce vehicle miles traveled by 5%/quarter?") is often the key to solving big problems (like, say, "How do we eliminate carbon emissions?") You often don't know what small problems are worth solving until you actually enter a field and look around in detail. So pick an interesting field and get started - you can always start over if it turns out that the most interesting problems are boring, but you'll never know in the first place if you don't pick.
1. Don't forget that there are other people out there! It's possible for a problem to be important, for many people to be working on it, but for your honest assessment to be "I'd just get in the way, because I have neither the talent nor drive to effectively contribute to solving the problem." That's fine - go work on problems that you can contribute to, and through the wonders of our market economy, you end up making life easier for the people who are working on the problem. There's a strong argument for thinking in relative terms when deciding what problems to work on, i.e. "What can I most contribute that other people can't?" rather than simply "What can I most contribute?" or "What most needs doing?"
2. Young people - particularly young people who are really good at rational & logical thought - tend to underweight their emotions when deciding what to work with. You're going to be stuck with them throughout all of the actual work, so it's very difficult to be effective at problem solving when you don't actually enjoy the problem solving.
3. Many really big problems got that way because they're effectively unsolvable. When I was a teenager, the biggest problem facing earth was arguably climate change, which is arguably still the biggest problem. In the 15 years between my HS graduation and the Paris Accords, we made negative progress toward solving this, and then a year after the Paris Accords we reversed all the progress we'd made. Now, the best science available shows that it's effectively too late, we're screwed, and we should focus on harm-mitigation. Everybody knew it was a problem in the 1990s and even the 1980s, but fixing the problem required cooperation from powerful entities that had every interest in not fixing the problem, and that sort of cooperation is basically impossible to achieve. While big ideas like this sound great and get people fired up, you usually accomplish more by working on small problems with no opposition and then putting yourself in a position where you can solve the big problem without the consent of all the people who caused it in the first place.
4. Realistically, small problems are much easier to solve than big problems, and solving a bunch of small problems (like, say, "How can Uber or similar competitor reduce vehicle miles traveled by 5%/quarter?") is often the key to solving big problems (like, say, "How do we eliminate carbon emissions?") You often don't know what small problems are worth solving until you actually enter a field and look around in detail. So pick an interesting field and get started - you can always start over if it turns out that the most interesting problems are boring, but you'll never know in the first place if you don't pick.