IMHO the #1 thing you can do is not use a car and help others not use cars, including working to get the infrastructure necessary in urban, suburban and rural contexts to make that possible. That is what I put my energy into on a local level.
What we should be doing is getting governments to band together and penalise industrial-scale polluters. It would do more good to take shipping and trucking electric than for you to rely on public transit and for me to drive one fewer kilometre.
That's the person who incentivized the polluters to pollute in the first place. The individual had no standards except an expanding "quality of life" and they were given just what they demanded: consumption without regard for consequence. This attitude perpetuates it.
You vote with your dollars. Our current corporate players are who we paid them to be.
When a hole was developing in the ozone layer advocates spent years trying to get people to stop buying the chemicals that were responsible, to no avail. Same with the issue of lead in gasoline and white phosphorous in matches. The solution in all those cases was to simply pass laws to stop a handful of companies from producing those products rather than try to raise awareness in millions of people.
I agree with this as well. We should do all of the above.
It also doesn't work, while serving as a political shield to protect industrial-scale polluters. But it allows you to deliver with hauteur, so it passes generally without comment and things continue to get worse.
The problem is this mindset. Build better and more sustainable cities instead of the suburban hell that is in most of North America
There aren't enough sufficiently-walking-friendly places to live at affordable enough rates to support most individuals in the United States going "welp, guess I'm not gonna drive". Devolving to individuals erases responsibility at levels where the necessary power actually exists.
A better approach might be to add a tax to carbon-based fuels that is used to fund carbon capture.
And one big thing that Americans can all do first is give up the idea that you have to do something perfectly or else you're a total failure at it.
Fact is the vast majority of humans reproduce and will continue to do so, no matter how many comments on HN try advocate otherwise.
But I'm an optimist; go childless, we've got headcount more than covered here on Earth! Don't let society make you feel guilty or selfish for not throwing more fuel on this raging inferno of a dumpster fire.