If the claims of climate change people were true, that we are facing existential destruction in short order - then how is it possible they are denying a tried and true solution?
We could have reached 'Paris targets' long ago were we to have kept deploying Nuclear installations, in the terms that we understood decades ago. With fewer accidents. Etc.
The denial of a tried and true solution to this supposedly existential crisis destroys their credibility, and therefor their claims. That's not to say clams aren't valid, but that we can't trust the vanguard of the people behind the climate movement, obviously.
It's incredibly naive (but maybe understandable) for people to not understand that the issue of climate change is hugely politicized and ideological, and because of that, it's hard to make heads or tails of a lot of information.
People running around screaming that the sky is falling - and not talking about Nuclear as part (possibly the basis) of the solution - are spreading irrational fear and hysteria. There's no reason to talk about 'mass flooding' if we can solve the problem in a fairly straight forward manner.