I think Al Gore did more harm than good. He made himself the face of global warming and it helped spark a partisan backlash. There was a time when Republicans were not particularly skeptical of global warming. That shifted as climate change and Al Gore became more and more synonymous in the public consciousness.
Is that Al Gore's responsibility or is the Republican's responsibility of their policies being basically "anything that Democrats do is bad and therefore we oppose it"?
I don't think it's his responsibility, but that was the outcome. I would say most of the responsibility lies with the fossil fuel industry and their PR agencies who funded propaganda that took advantage of the situation.
