The science is hardly settled. It's pretty shitty in a lot of ways. I have the impression the bulk of scientists who have studied this do believe mankind is affecting climate change, though. I am not convinced a net warming is necessarily bad, though. I've never seen anybody say what the perfect temperature is. Somebody just tell me what the normal temperature is and back it up with something other than a pack of lies.
Absolutely we should always be working toward definite, undeniable truths such as: Clean air is better, cleaner earth (not polluted) is better, clean water is better. Most of these things coincide with what hardcore climate change people want. We have been and we are. I understand the point of continued vigilance such that we don't slip back into bad practices. Nobody is spouting off about going back to the way things used to be.
It looks to me like the republican mantra of mocking all this is going to be on the wrong side of history. Perhaps so, but as you touch on in your next sentence, if Republicans don't speak up, the left will go off the deep end to assuage their fears. We have people lying to us continually to justify their agenda. There needs to be an opposing force and if the Republicans are the ones fulfilling that need then so what? Someone must. At the same time the opposite side overcompensates by making insane and totally false, and regularly wrong predictions about what's going to happen. But to be clear I think the former is worse than the latter.