100% nuclear would work too but is politically unviable. Waste and the risk of accidents are a big problem, but at this point I believe they would be preferable to breathing in fossil fuel emissions all day.
Every existing light water reactor in the world could melt down like Fukushima and it won't come close the human disaster that will happen if much of the world's climate exceeds a wet bulb temperature of 35C for any part of the year.