What kind of a critical mind does it take to be a Dittohead, a follower of Rush Limbaugh? The man himself, "America's Truth Detector," led by example last week, when he broadcast news of a scientific paper titled "Carbon Dioxide Production by Benthic Bacteria: The Death of Manmade Global Warming Theory?" The paper was a hoax. (The Web site for the invented "Journal of Geoclimatic Studies" that "published" the study has been taken down; the paper is cached here, and the New York Times' environment blog has a good rundown of the whole affair.) To a climate-change denier, though -- especially one conditioned to believe that the scientific establishment is out to get him -- the paper had a ring of truth. In the article's abstract, the embattled "authors" complain that a "powerful and hostile" scientific establishment turned a deaf ear to their hard evidence: "When we have challenged prominent climate scientists who subscribe to the climate change 'consensus,'" the "authors" wrote, "our concerns are met with evasion and in some cases aggression. Discussion of this issue has been all but prohibited by the editors of peer-reviewed scientific journals. This journal is a courageous exception, but it too has come under great pressure not to raise the issue."

Cue the bloggers.

"I applaud the courage of these researchers to put forth their study which will almost certainly be viciously attacked by the global warming cultists," said a blog that styles itself "Florida's premier conservative Weblog." On his blog at Reason Magazine's Web site, libertarian Ronald Bailey sounded a slightly milder tone: "This is a rather sweeping conclusion from research published in a minor journal and will likely produce howls of outrage from defenders of the consensus. Only further research and time will tell if these guys are on to something significant or if they have somehow misinterpreted what they believe they have discovered." Not exactly. Had any of these commentators read beyond the article's title, they would have quickly happened upon something in the introduction that might have at least prompted some skepticism: "Significant fluctuations in benthic eubacterial populations ... cause far greater impacts on atmospheric carbon dioxide concentrations than all other ecosystem effects." In other words, bacteria at the bottom of the ocean have more effect on the atmospheric carbon dioxide ultimately blamed for warming than everything else in the world. When the hoax was revealed, some of the victims launched counterattacks, decrying left-wing "black P.R. ops," and warning of more to come. Many of them gave good-natured mea culpas. One act of contrition stood out. Roy Spencer, a prominent climate-change denier, took the blame for the head Dittohead's embarrassment: "I sent an e-mail to Rush about the issue regarding the hoax, with a copy of the 'research study,'" Spencer wrote. "Unfortunately, my very brief note to Rush was not very clear, and he thought that I was calling global warming a hoax, rather than the study."

Update: Limbaugh almost immediately informed his listeners that the study was a hoax. "I''ve got to apologize to you, I've been hoaxed," he said shortly after describing the study on his show last Thursday. Limbaugh said Dittoheads should "disregard" what he'd said about the study. Then, in a rare bit of honesty, he said that he's usually the hoaxer, not the hoaxee.