Jeff Fecke at Shakesville has noticed something that I've also noticed: The language and tone of denialists is remarkably similar, whatever the subject is:
The Tune's the Same.... He notes that deniers of climate change, evolution/natural selection and domestic violence use similar arguments even though their areas of interest seem to be far apart.
Denialism is basically what happens when a controversial idea becomes the conventional wisdom... there are always some people who, for whatever reason, will not accept it and so they seek excuses for denying the idea.
They tend to refer to themselves as "skeptics" rather than deniers, but this is misleading. True
scepticism involves healthy doubt, an open mind, and respect for the truth. Skeptics seek knowledge and will change their minds when they encounter convincing evidence.
Denialism, on the other hand, is less concerned about truth than about "winning", and denialists, when faced with evidence that disproves their convictions, will ignore it, attempt to explain it away, or try to suppress it. And then, in an impressive bit of projection, they will often claim that their opponents are the ones suppressing the truth.
Holocaust denial is probably the best-known (and arguably the worst) example of denialism, but I've seen some people make a case for climate change denialism being worse, on the grounds that it has more potential for increasing human suffering. In the short term, at least, this will probably be a "fringe" opinion, as many respected institutions, including the US government, have not recognized the threat of climate change until recently, and some (such as the Wall Street Journal editorial section) still have not. What is clear though, is that denialism is more immediately dangerous when people with wealth and influence embrace it... and in the case of climate change, it's definitely happening.