What matters is not what the president believes but what the people he represents believes and gives him votes.
Are we seriously gone pretend things like putting solar panel on the white house and putting so much emphasis on that was more likely to save CO2 anytime soon?
And it was in fact under Nixon and more under Carter that a number of nuclear efforts were stopped and replaced with things that had absolutely no chance of having great returns anytime soon.
I'm not saying Reagan was better, he clearly didn't turn that ship around. But the assertion that if it wasn't for him we would live in a CO2 free paradise because of carters investment in solar is totally delusional.