173
Voting is among the highest-impact actions you can take when it comes to greenhouse gases
(slrpnk.net)
Image comes from this paper
Americans can achieve even more by helping to get others to vote
This presumes that a vote has an impact.
In the US, right now, who holds power is still decided by who gets the most votes in elections. Even non-swing-states have congressional races, races for state legislature, and elections for local government.
If you're in a spot where you think your local vote won't be close, you can volunteer to turn others out to vote
But a vote doesn't have an impact.
It can certainly happen when things are close, as they are now. Even if all you do is change it from "close" to "not close" the impact is to keep it out of the courts.
What can?