From Al Gore, on why climate deniers get so much attention:
If the people that believed the moon landing was staged on a movie lot had access to unlimited money from large carbon polluters or some other special interest who wanted to confuse people into thinking that the moon landing didn't take place, I'm sure we'd have a robust debate about it right now.
I just happen to have a good example of this on tap. Last night I read a post over at Volokh about how climate data was being faked. I sighed and moved on. Then, about an hour ago, I got an email from a conservative reader asking if the Volokh post undermined my faith in global warming. I told him it didn't. Then, a few minutes later, I noticed Megan McArdle linking to the same post. Obviously this thing wasn't going to go away quietly.
Basically, the Volokh post (by Jim Lindgren) passes along an analysis by Willis Eschenbach claiming that the instrument data for Darwin Airport in Australia shows flat or declining temperatures if you look at the raw data, and only shows an increase if you "homogenize" it. Conclusion: the evidence of warming isn't from the data at all, but only from the manipulation of the data! But via Tim Lambert, here's an excerpt from the original NOAA paper that explains how the homogenization was done:
A great deal of effort went into the homogeneity adjustments. Yet the effects of the homogeneity adjustments on global average temperature trends are minor (Easterling and Peterson 1995b). However, on scales of half a continent or smaller, the homogeneity adjustments can have an impact. On an individual time series, the effects of the adjustments can be enormous. [Italics mine.]
So, if you're a climate denier, what would you do? You'd look for local effects and you'd look for an individual time series. Look hard enough and you're bound to find some with large changes due to the homogenization. And then you'd cry foul. The books are being cooked!
Well, as I told my emailer, I'm not qualified to judge this stuff. Neither is he. Neither is Willis Eschenbach. But it's easy to make a pretty graph that looks damning and then demand that the scientific community address it. And when they don't — because it's amateur crap and isn't worth anyone's time — the deniers have a scalp. Look! The scientific community is so corrupt they won't even look at our evidence! And Fox and Drudge and the Wall Street Journal all merrily pass it along.