A more general question about capitalism can be considered here: Who holds responsibility, consumers or producers? Both?
In my view, consumers who choose to lower their demand of fossil fuels (by using the bike instead of the car and reducing their vacationing on different continents) actually make a difference. If people stop consuming, companies go out of business.
Investing on the other hand is a zero-sum game: If a promising opportunity exists, somebody will finance it. Anything else is unstable in a game-theory sense, it's like asking people to not pick up $100-bills from the street.
In simpler terms: If you own Exxon shares you are not making climate change worse, but if you eat meat and own a car, you do.