Once the big stuff is paid off I can no longer justify not working on climate change. So what are the current most promising directions for fighting climate change, where an experienced software engineer can make a real contribution? What are the most effective organizations working on them?
Try to convince other people in your peer group to do the same.
But I assume the best thing one can do, get involved and spend time. Whether in local politics, companies trying to move things forward, NGOs, I don’t know.