Skeptics come in two flavours. The first flavour includes those who are misinformed or uninformed. They are skeptical of the science behind climate change because they are not familiar with it. They see the debates in the media and assume that similar debates occur within the scientific community. Once you show these people that no such debate is occurring within the scientific community, and explain the importance of peer-review these skeptics usually realize their misinformation and are willing to accept the science.
The second flavour are a rare bunch, most have been convinced by the overwhelming evidence to support the consensus. The few that remain are fully aware of the scientific consensus, don’t question it and yet for one reason or another they remain skeptical. One of my professors at UBC was one such skeptic, and even he contributed to several IPCC reports (so much for the notion that ‘non-believers’ aren’t given a voice). He was fully aware that his views were the overwhelming minority within the scientific community, and realized that it was likely that he was wrong and the consensus was correct, thus he fully accepted that it would be irrational for policymakers to listen to him over the rest of the scientific community.
Deniers are a different bunch all together. They deny the science even when it is right in front of them (hence their name), they believe in a grand conspiracy consisting of the entire scientific community that works to silence anyone who disagrees with the accepted orthodoxy, despite the fact that there is no data to support such claims and plenty of data to support the exact opposite, they purposely and dishonestly misrepresent the science, they dismiss the peer-review process and yet are willing to accept anything no matter how absurd if they believe it will cast doubt, they attack scientists, they abuse complexity and they present no consistent theory or synthesis of knowledge.
A major difference between someone who is trying to reason scientifically and someone who has a fixed belief they are trying to defend against rational inquiry is the scientific thinker is looking for synthesis. They want things to fit together nicely, to make sense, and incorporate as much of the data as possible into a cohesive picture or theory that is convincing to ones peers so they adopt your view.
A crank, on the other hand, doesn’t care about internal consistency, presenting a cohesive picture of any kind, or creating a body of knowledge to be adopted and utilized by their peers. If someone has a different theory that is completely different from theirs they don’t care, as long as it remains opposed to the scientific theory that impinges upon their fixed belief.
Deniers are not willing to look at the issue with an open mind, they have already made up their mind and will clutch at anything no matter how irrational or absurd it may be. The recent claim that the APS reversed its position on climate change is a prime example of this.
the bigger failure here is that of the APS not realizing they were dealing with a den of snakes when they opened up any publication to the likes of Monckton. Never mind that Monckton’s paper is about as big a challenge to the theory of anthropomorphic climate change as a poodle wearing boxing gloves is to Mike Tyson; as has been said before, denialists aren’t interested in debate, they are only interested in the appearance of debate. This non-peer-reviewed publication in a newsletter is being touted by cranks all over the internet as proof that global warming is being debated in the halls of academia because it is under the auspices of the APS. When the APS clarifies, correctly, that this is not an example of peer-reviewed publication, they get attacked by Milloy and others as stifling debate and caving to the global warming conspiracy.
The bottom line is that skeptics are worth talking to, but deniers will not be convinced no matter what the evidence points to. Their responses enviably boil down to a variation of sticking their fingers in their ears and yelling. This presents a problem for which I have no real solution, deniers will clutch to their unscientific positions in the face of mountains of evidence that points to the contrary, but at the same time their arguments, while unable to stand up to scientific scrutiny, are convincing enough to fool the uninformed skeptics. How does the scientific community (and those who accept their conclusions) effectively counter these anti-science deniers?