Yes, we have proven solutions, that's the easy part. Now go convince 8 billion people to adopt them.
Your view is US-centric (so 4% of the Earth population) but let's run with it. Donald Trump is in power because he has been elected, he has been elected because he has the support of the general population, and he did that by openly not giving a shit about climate change, against a now clear scientific consensus. It is even taught at school. People simply prioritize their comfort over greenhouse gases, and they have a leadership to go with that.
And yet, compared to the rest of the world, Americans have it really good. Doing the necessary efforts is just a matter of comfort, it can be done (but the population doesn't want to). But for the majority of the world population, getting to survive at all is what matters, they don't have resources to spend for the environment, and they won't until they get to the standards of living of the first world. So what are you going to do? Punish them for it? That's one of the catastrophic scenarios.
You are saying that what is missing is leadership. A way to reformulate it is that we are missing a dictator. Maybe a China-like government but for the entire world could work. But be realistic, it won't happen.
The problem with climate change is that it is a slow process and kind of a prisoner dilemma situation. Why should I make any effort, it probably won't affect me in my lifetime? A lifetime later, as things are starting to become really bad and people are ready to take it seriously, then it is too late, and that's when the emergency solution will come handy, to buy back the time we lost so that we can do it properly.