If you created a HN-like site to facilitate communication on a broad range of subjects, your goal would be to get the right sort of people to actively participa

If you created a HN-like site to facilitate communication on a broad range of subjects, your goal would be to get the right sort of people to actively participate in constructive discussions. You'd end up casting a pretty wide net and I'm not sure how much good could come from a bunch of people talking and not doing. However, when you focus on a specific project, knowing that it's much more reasonable to assume you'd be getting more done in terms of actually solving climate related issues, then discussion that is needed can happen a lot easier, with your team and with the smaller net you cast when needing specific feedback.