As you said, at your level it would be raising awareness, make efforts to reduce you footprint as much as you feel comfortable doing, you can also get involved in organizations that can work at a local level (lobbying for more bikes and public transportation in your city for instance) or donate to green lobbies.
On a higher level, the most you can do as a person would be to vote for people with sensible ecological and social programs, you can also get in touch with your representatives when possible.
This is a big case of the snowflake not feeling responsible for the avalanche. As an individual you will not make any significant change but if everyone feels the same and organizes and move as one, it does make a difference.
It definitely feels hopeless, and I'm also extremely pessimistic about the future but hopelessness leads to helplessness, and giving up will only destroy every possible positive outcome.