What we have not yet realized, as a society (or species) that we have a limited amount of energy available to use, without destroying ourselves. Fusion/fission generates large amounts of heat, which we use to boil water and drive turbines, but the water that leaves those turbines is very hot—which we put into cooling ponds and cool by using rivers, etc., to cool. This is another way to say that "we are using nuclear fission to heat the planet."
When we develop fusion, it will generate enormously increased amounts of heat, so it is not the final solution, because if we keep increasing what we consume, we will increase the amount of global warming.
Solar power is about the best we can do. We need to stop trying to use more energy and instead work on reducing our consumption of energy. Get rid of pavement, as much as possible, which heats the planet enormously.
https://en.wikipedia.org/wiki/Gasoline_ ... equivalent
But I don't think any of this is gonna happen. Instead, weather and oceanic flooding will take care of the majority of us and those remaining will have to muddle along as best they can.