> The vast majority of people are greedy, uneducated and selfish.
That's a naive view of human personality. The reality is that all people are "greedy" and "selfish" in that they consciously or subconsciously pursue their own interest. (Some people do suffer from various degrees of developmental trauma that affects their ability to do that easily, but the part of the brain that is responsible for that still exists. "psychologists" sometimes refer to this as inability to perceive borders, perception of self etc).
Now, the set of people that you are referring to by exclusion, i.e. those that are not "greedy, uneducated and selfish" simply find themselves in a priviledged position and signal virtue by painting themselves as climate conscious individuals. Of course, the brain hides most of the real motivation behind this reasoning.
Are there also people who want to see the world burn? Absolutely. Again trauma does that to people. But most mentally "healthy" people don't want the planet to become uninhabitable for human life.
This is all coming from someone who was at one point in life deeply affected by intense destruction of natural ecosystems around, intense logging, illegal deforestation. I was an avid cyclist and used to love nature and was seeing the destruction on my rides. But you learn to accept that, this is the way of life.
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Now, to answer to original question. What must happen for humanity to coordinate on solving this problem? I don't expect humanity to be able to do it. But I think what would need to happen as a stepping stone, is to end most of the conflict in the world right now. This is of course impossible to do in one generation. When you stop seeing the world in "us vs them" and the vast majority of people emphatize with everyone else and other life forms, i think coordination is possible. I doubt humanity will reach that point though.
The vast majority of people are greedy, uneducated and selfish.
Fix that and you won't just fix climate change you'll fix a lot of our issues.