Edit: I'm wrong about the reason, because the comments aren't more than the points. But the point stands, it's algorithmic, it's not some conspiracy against discussing climate change. It's that it's a boring discussion that doesn't add to anyone's understanding.
EDIT: The post doesn't follow the algorithm. But still, it's algorithmic, stop being conspiratorial."
There is something called a flame war detector that I've seen referred to by the moderator. From experience this kicks in when comments overwhelm points as I said. I expect it's more sophisticated than that, and as I pointed out, comment to point ratio was clearly not the trigger here.
The next post plausible explanation would be a moderator lowered it's weighting because the discussion was skewing into a rehash of boring arguments.
I can also picture that some people flagged it (though usually this gets a [flagged] appended so it's unlikely. Maybe that qualifies as the community rejecting it and legitimizes the OP's complaint.
The least likely thjng possible is some kind of conspiracy to bury climate change stories.
You could argue that if a discussion is heated, at some points both sides run out of arguments and things like Godwin's law kicks in, so letting it continue is counterproductive. On the other hand, I saw interesting and highly upvoted posts disappear after just a couple of comments (because they were politically incorrect, criticized someone, or were in favor of someone currently out of fashion).
This "I dislike so I flag" abuse (by a minority) is my single gripe with HN. Otherwise, it's by far the best community on the web and I'm happy to be a part of it.