Discussing climate change has never been banned; this sort of claim is easily disproved by even the most cursory of searches in the box below. Try it.
Here, I’ll say it right now: climate change is real, it has deleterious effects on our world, and we should take collective action to mitigate or even reverse it.
Now, there’s an expectation that commenters conduct themselves appropriately and contribute to the overall well being of this site. If a person misbehaves when discussing this or any topic, that’s when they get spanked.
> de facto banned
seems a little strong, but I understand why they say this
> climate change is real, it has deleterious effects on our world, and we should take collective action to mitigate or even reverse it.
plenty of comments on HN to this day will disagree, saying climate change is some anti-progress conspiracy or hasn't been studied enough or won't be that bad, etc etc.