Partisans can't stop themselves from being partisans and make every climate thread about partisanship. There's little to no actual discussion about climate science. It's just another excuse to engage in showy partisanship. So the thread gets flagged and likely sets off some of HN's auto-flagging triggers due to commenting patterns common to threads that get out of control.
Fear of change and especially fear of the radical change that may well be required to avoid horrific harm.
Because in the US climate change is denied by approx. 35% of the general population and around 69% of the self identified republicans... so to that audience any mention of climate change is an offense to their identity...
and as we know from behavioral economics, people will ignore or downright reject any evidence that doesn't support their preconceived notions.