Ozone depletion too was a global problem that needed international coordination to solve. But the reason why it was solved while the climate change crisis wasn't, isn't the 'level of difficulty' you're referring to. It's the perverse economic incentives behind the centralized fossil fuel trade. Unlike ozone depltion, climate change issue was known at least as early as 1892. We had more than enough time to find and implement the solutions. But even today when we have viable long term solutions, the pervesion of global politics against them is splendidly evident. We really could have solved the climate change crisis if we wanted to.
That's why I always emphasize shifting the market dynamics - the supply and demand balance. That's the only way we can overcome those perverse incentives. But people simply refuse to connect the dots that deep, instead preferring to insult those who do. And the reason is simple. It will break the comfort bubble that you're in, if you have to take some responsibility to solve it.
> There is no much harder goal than surviving on Earth, and we are measurably not only completely failing, but we keep accelerating in the wrong direction! We are making it worse, faster everyday.
If only there was/were some solution(s) for that.... Oh! Wait!