I am just worried that your platform might turn into a debate forum with endless back and forth arguments instead of being a "community for discussing positive climate actions". Discussing actions assumes you already agree on what the problem is. If you want to be successful, focus is the key. And to enable focus, you need to guard your community. Heck, HN is successful and heavily moderated.

edit: If you are serious about solving climate crisis, there is no time for counter arguments. Arguing with deniers and "sceptics" is a distraction and a waist of time. They are already a minority anyway. The majority of the population, both in US and EU, supports climate policies. The task is not to convert sceptics, the task now is to get the pro climate majority off their butts, away from their keyboards, and to "the streets".