Climate change deniers will still deny it, even as their own bodies, homes and families are burning.
They're no different from anti vaxxers, flat earthers or people who think homeopathy works and just as delusional, it is a sickness that enables the pain and suffering of others
I think that denial is more a weak spot of human nature that can grow into a sickness... but it is not a sickness per se.
so... how do you encourage a setting in society that handles that weak spot better
Look at history
For example there is a common opinion shared by elite and the common people on how something is
Then you get some weird scientist (or scientist avant la lettre) that tells that the common opinion is wrong.
And perhaps that "scientist" did it in a provoking way because nobody wanted to listen to him when he told it first non-provoking.
Galileo the classic example.
Whether the new insights were taken over depended very much on the practical value on the one end (fast benefits at low treshold of resources and time lapse) and how much it would disrupt the status quo (the power and/or the comfort bubble) on the other end.
Makes me remember a story of someone who spend in the 80ies after her study 5 years in West-Papua as youth development worker among tribes. BTW physical abuse (beating of wifes and children) a real big and persistent problem there in coastal westernised villages since many decades. She told me that when teaching children one of the Elders of the tribe was there in the class as well.
It had two effects:
1. he learned what the children learned (=> he learned what was going to disturb the status quo)
2. By being there, he, as Elder, one of the "authorities of the tribe, blessed off that this change was going to happen.
For everybody crystal clear and imo a prudent approach.