Theism is often a default test of irrationality on Less Wrong, but I propose that global warming denial would make a much better candidate.
Theism is a symptom of excess compartmentalisation, of not realising that absence of evidence is evidence of absence, of belief in belief, of privileging the hypothesis, and similar failings. But these are not intrinsically huge problems. Indeed, someone with a mild case of theism can have the same anticipations as someone without, and update their evidence in the same way. If they have moved their belief beyond refutation, in theory it thus fails to constrain their anticipations at all; and often this is the case in practice.
Contrast that with someone who denies the existence of anthropogenic global warming (AGW). This has all the signs of hypothesis privileging, but also reeks of fake justification, motivated skepticism, massive overconfidence (if they are truly ignorant of the facts of the debate), and simply the raising of politics above rationality. If I knew someone was a global warming skeptic, then I would expect them to be wrong in their beliefs and their anticipations, and to refuse to update when evidence worked against them. I would expect their judgement to be much more impaired than a theist's.
Of course, reverse stupidity isn't intelligence: simply because one accepts AGW, doesn't make one more rational. I work in England, in a university environment, so my acceptance of AGW is the default position and not a sign of rationality. But if someone is in a milieu that discouraged belief in AGW (one stereotype being heavily Republican areas of the US) and has risen above this, then kudos to them: their acceptance of AGW is indeed a sign of rationality.
It could be explained, that every year isn't hotter than the previous one. But how can you explain that 2011 was not hotter than a year a decade or more ago?
What are those natural factors which shadow a BIG change in the CO2 level over decade or so?
Could you explain the down-vote please? (My apologies if it wasn't you).
At the risk of another downvote, it seems your mental model of AGW is rather "AGW predicts that for each year y, the temperature T(y) in year y must exceed the temperature T(y-10) in year y-10; since we have observed a counter-example, AGW is falsified".
Is that correct? If so, could you cite a paper or presentation by climate scientists (or summary by IPCC etc) which makes such a prediction?
Here's a hypothesis to think about: Suppose the AGW trend (imposed on the climate no... (read more)