It’s when you try to get them to consider why that might be the case that their brains start turning to mush

It's not their brains turning to mush, it's their rational thoughts bumping right up against decades of propaganda by oil companies, the right wing media, and conservative politicians that have ingrained the idea in them that believing in climate change makes you part of the radical left.

And ultimately it's easy to get people to (especially conservatives, who - by definition - are resistant to change) not believe in climate change, because it's scary as fuck, and because solving it will involve huge overarching societal changes. Much easier to pretend it doesn't exist. That's not just climate change, that's just how the human brain likes to deal with unpleasant facts - hell, that's how most people cope with the concept of their own mortality