I work in ecology, and yeah it's depressing. There's a really obvious solution to climate change but no one in leadership in the West is willing to say it and this will make your job feel pointless and it isn't. You can still make a difference in people's lives through other means. You're not going to fix climate change, but you can still get meaning out of the relationships you form and things you accomplish professionally. I work in a niche field of pollination ecology and my research more than likely will not "matter" but I've still setup urban public gardens, consulted with habitat enhancements for non-profits and local governments, and educated a ton of people through lecturing, mentoring, and teaching -and while that stuff isn't going to stop climate change it still matters because it matters to me and I think it's a good use of my time. And if that isn't enough remember that people love and care about you.