The increasingly public “skepticism” of aging weatherman John Coleman raises an interesting question: Do you have to be corrupt to be wrong about climate change?

The answer, of course, is no. Notwithstanding the money that Coleman makes as a guest speaker for oily conferences organized by long-compromised groups like the Heartland Institute, he may be sincere, even well-intentioned about his personal campaign to dismiss climate change as “the greatest scam in history.”

But that doesn’t absolve him of responsibility, especially as he is leveraging a high profile to interfere in a debate about which he is clearly ill-informed. Because given his ability to command an audience, and given the public’s tendency to confuse weather with climate and to actually take someone like Coleman seriously as a scientific commentator, there is a real danger that people could believe what he says. And that would be a crime.

Coleman burst on the denier scene a couple of years ago with a 1,000-word screed that was snapped up by denier frontgroups like ICECAP and distributed by the Drudge report. ICECAP continues to celebrate the result, boasting (as if it’s somehow relevant) that “KUSI and Icecap received hundreds of emails, better than 90% favorable.” (How would you expect readers on a denial website to react to a new spokester denying climate change?)

ICECAP acknowledges that “there were of course some negative responses,” but dismissed these as “mostly ad hominem attacks questioning motivation as is typical in this issue.”

Well, not having access to ICECAP’s emails (wouldn’t THAT be a treat), we can’t comment on the exact nature of the criticism. But in the light of Coleman’s own analysis, it’s worthwhile to review the actual meaning of the term, ad hominem. Wiki puts it this way:

An ad hominem argument, also known as argumentum ad hominem (Latin: “argument toward the person” or “argument against the person”) is an argument which links the validity of a premise to an irrelevant characteristic or belief of the person advocating the premise.

The notion here is that you might dismiss someone’s views on climate because, say, they are not nice people – because they are unkind to small animals or unreliable to their friends.

That’s not the case with the general criticism of Coleman. You can fairly dismiss his views because he has no expertise. He’s a weather forecaster and has been since he was 19. He has never studied atmospheric science and, even as a self-proclaimed expert, he seems not to know the difference between being a meteorologist and a climate scientist.

If you want the whole backstory on Coleman, it’s available here in an excellent article by the Columbia Journalism Review.

But if you want a really excellent example of ad hominem argument, you could look at Coleman’s own original essay, a downloadable copy of which is available on the ICECAP site. Here, Coleman advises that scientists – virtually all scientists, including members of his own family – are isolated, agenda-driven, single-minded and corrupt. According to Coleman, the overwhelming majority of these horrid individuals “manipulate the data to come up with the results they wanted to make headlines and at the same time drive their environmental agendas.” Other scientists go along with them because they all care – above all – about their research funding. The almost invisible band of scientists who, by Coleman’s judgment, actually have a conscience, has been silenced by the environmental mob.

That’s not merely an ad hominem attack. It’s flat out libelous and would be actionable if Coleman attached a name to his criticism. It’s also stone stupid. While we at the DeSmogBlog are happy to suggest that, say, Pat Michaels or Fred Singer are compromised beyond credibility buy the money they take from the oil industry, we would never actually accuse every deluded denier in the world of greed, selfishness and professional malfeasance.

Coleman shows no such restraint and one can only imagine how he faces his brother – who actually HAS a science PhD – when they get together over the holidays.

But that’s pretty much all Coleman’s got – a vast conspiracy theory. If you look at his actual argument – the literacy-challenged essay or the sometimes-stumbling TV presentations like this one – you’ll see a nice man, past his prime as a news-caster and well past his best-before date as a scientific source. You will see some carefully manipulated graphs that are not sourced and that are cut off to prevent us from having to consider that the recent global warming is, indeed, more severe than anything seen in a thousand years and is moving more quickly than any climate change in many thousands, maybe hundreds of thousands of years.

Coleman may be sincere. He may be well-intentioned. He may be a charming dupe. But he should be ashamed of himself for not taking more care in what he reads and who he befriends.

And the rest of us should ignore him more enthusiastically than the good people of San Diego ignore his weather forecasts.