There is ideological diversity within the democratic party, especially at the local level. As part of a representative democracy, the electorate needs to be engaged with their representatives. You should start looking closely at your most local representatives.
I agree with a lot of people that suggest voting and holding your representatives accountable and the mass pollutors responsible will be the most important part but I also think there’s no reason not to lead by example in this situation. Reduce your carbon usage when you can by buying fewer consumer goods, eating less meat, avoiding single use products, and more frequently using public transportation, walking and cycling to get around.