Earn lots of money and then invest it in an early-stage organization that has a decent plan to battle climate change.
It's amazing how many people think showing up to work at a soup kitchen, and only then on Thanksgiving and Christmas Eve, when they're way overstaffed, is going to solve homelessness, when they could have achieved 100x the benefit by working those hours at their regular job and donating the cash proceeds.
Don't fall for the same fallacy when it comes to climate change.