The problem is not as much denialism, as what causes denialism. As long as people benefit from fossil fuels, the meat industry and so forth, they are going to defend that. The key is not to create more pain, but to reduce the number of people benefiting from destroying the planet. In other words, climate action has a positive feedback loop. Success anywhere also helps other people. For example if Germany shuts down coal power plants, that is good news for Colombians fighting coal mines producing the coal, which was exported to Germany.