I think most people who don't believe in climate change don't believe in it because of the amount of money and political power that is devoted to discrediting it. Let's be honest here, most people on _either_ side of the fence (full disclosure: including me) don't actually read climate research, they're only aware of what gets covered in the press, which tends to be the research that's more apocalyptic and less focused on model adjustment, etc.

This is only really an issue because of the way that climate change has been unnecessarily politicised, though. We see dramatic stories reported on from other areas of research ("Hey, we found planet X!"), and yet there hasn't been a huge amount of effort spent on discrediting astronomical research, so the public accepts that the peer review process has worked and there's no controversy ("Scientists are all just elitist liberals, where's the research from conservatives that says planet X doesn't exist?").