(I was once talking to a friend over beers, ranting about some politics I was unhappy about. And he asked me: So what are you doing about it? Of course, I wasn't doing anything besides complaining, and this made something click in my head. All of my self-important opinions were worth nothing if I couldn't be bothered to do anything about them. I think about this a lot and it has changed the way I see the world.)
P.S. the thing about what a single person can do is just so much, for a real impact it really needs governments to set policies which causes fundamental change. Does the government continue to build motorways, does the government sets up an environment which is benefitial for investments in renewable energy or in coal. all this has a much bigger influence then my personal decisions.
Vote! While there are some things I can do personally (some I do, others I can improve on) the largest changes will be politically driven, so I'll vote for parties the promise the best policies to reduce emissions, whatever they may be.
When you have major political parties lined with deniers it's not a hard decision with pros and cons to weight up.