https://en.m.wikipedia.org/wiki/Green_party
You can tell they are effective as they get regularly attacked by people here who seem to have a visceral hatred of them and very weird justifications for why (they're under the thrall of the fossil fuel companies apparently)
Anyone that advocates for increasing democracy generally, whether more representational democracy in existing democracies that have broken systens (US or UK) or spreading it further. People generally want action for climate change, the people who don't need to spend a lot of money and tell a lot of lies to hold this back. The more democracy the more they'll need to spend.
Electoral Reform Society
https://www.electoral-reform.org.uk/voting-systems/what-are-...
George Soros's Open Society Foundation
https://voxeurop.eu/en/how-george-soros-was-transformed-from...
HN types might be more attracted to the business or analytical sides though. Carbon Tracker or Bloomberg New Energy Finance which proceed from the premise that climate change is inefficient and there's market based opportunities there to be exploited.
https://about.bnef.com/contact/
Within big orgs like Google and Microsoft they have similar teams I believe, looking for the cheapest and most synergistic ways for them to save money and help the climate at the same time.