I don't believe that any authority on earth could convince everybody that climate change is not real, because the people who don't believe in it don't simply draw their beliefs from the authority of others. If they did, they'd be willing to listen to climate scientists. I read a great article recently about why conspiracy theories are so persistent and the people who believe them can be so fanatical about them.

https://www.psychologytoday.com/blog/talking-apes/201801/why-do-people-believe-in-conspiracy-theories

Researcher found three main reasons for people holding onto false beliefs even when confronted with the truth

• A desire for understanding and certainty: When confronted with proof that a belief is false, particualrly if that belief is fairly trivial, most people would simply change what they believe to be true. Both those who believe conspiracy theories often have a vested interest in maintaining them, through taking the time to understand their arguments. Being confronted with contradictory evidence is thus an unpleasant experience that challenges their feeling of certainty and threatens to render their invested time useless.

• A desire for control and security: Feeling as though you understand the truth, contrary to what others want you to believe, is a powerful emotional state, and one that its hard to shake off.

• A desire to maintain a positive self image: Socially marginalized people are more likely to hold conspiracy theories to be true. The ease with which two people who hold the same beliefs can connect is greater than the ease with which those with opposite beliefs can. Believing in a particular theory can give an individual a place within a community.

If its psychologically uncomfortable to change what you fundamentally believe, most people will simply hold onto their own version of the truth.