I don't know.
It's clear to me where evolution denialism comes from. It's a fundamentalist religious motivation at one extreme, whereas at the most mild it's human exceptionalism1.
The Republican party is the political wing of the denialism movement and encompasses evolution and climate change, but it's less clear to me where the climate denialism comes from.
Clearly, both are motivated by the fact that we're dealing with very large, very slow issues; it's the same thing that motivated skepticism (scepticism for the euros) about continental drift in the fifties. The difference is that no one had a strong attachment to the status quo for drift, and the evidence eventually overcame the objections2. Similarly, evolution involves the very slow change of entire species over thousands of generations and climate change involves the change of the entire climate, all the ecosystems, all the oceans, and the entire atmosphere, over decades. We can't see a daily change, therefore it doesn't really happen, right?
Like evolution, there's a range of climate change denialists. At the extreme, you have people who deny that the change is happening at all. We're not getting warmer! Then there are those who think it's all part of natural cycles of warming and cooling, like the opposite of an ice age. Then there are those who admit there's an uptick in temperature, but it's an aberration, probably caused by the sun or something3. Then a shade closer to truth is that we are getting warmer and it is strange, but it's not caused by humans. Finally you arrive at the fact of the matter, and that's anthropogenic climate change.
This brand of denialism doesn't really spring from the religious well. There is an element of religious fervor to it, namely that man can't fundamentally alter what god has created, but that's not the main wellspring. It's mostly libertarian in origin. This is the same attitude that fought tooth and nail to protect chlorofluorocarbons and leaded gasoline. As with other denialisms, it's resistant to facts, but within a decade or so it will bow to inevitable truth. I hope.
That definitely won't be the case for evolution, where 150 years of evidence has failed to budge the fundies. Oh well.
I don't really understand why the libertarian movement would be GCC denialist, though. The Republican Party is anti-GCC because it might be expensive for business? Or because it's the environmentalist position and as soon as they understood that they had to stake out the opposite position? Either way, they're dicks, but why the apparent passion from the masses? Is it because they're so dedicated to their bloc that they honestly don't have to think about their positions? And what about the people who do think about their positions and don't put it in religious terms?
Honestly, I think it's just the libertarian opposition to any form of interpersonal cooperation that doesn't involve carrying guns in the woods. Working together? Sounds communist.
1 - Believing humans are exceptional. Everything else might evolve, but we don't!
2 - The real problem with drift was that it didn't have a mechanism at first and no one could imagine the continents simply plowing through the oceanic crust. They were right to deride that image, but philosophically in the wrong. Philosophy, honest philosophy, requires that you attack the strongest possible interpretation of your opponent's position, not the weakest straw man. The mechanism is that the continents don't plow through the oceans floor, but are instead pushed by the movement of the ocean floor itself.
3 - The sun goes through cycles of dimness and brightness, and the Earth is slightly warmed and cooled as a result, but right now it's on the decline and we're still getting warmer.