Creationists and climate change deniers have this in common: they don't answer their critics. They make what they say are definitive refutations of the science. When these refutations are shown to be nonsense, they do not seek to defend them. They simply switch to another line of attack. They never retract, never apologise, never explain, just raise the volume, keep moving and hope that people won't notice the trail of broken claims in their wake.

This means that trying to debate with them is a frustrating and often futile exercise. It takes 30 seconds to make a misleading scientific statement and 30 minutes to refute it. By machine-gunning their opponents with falsehoods, the deniers put scientists in an impossible position: either you seek to answer their claims, which can't be done in the time available, or you let them pass, in which case the points appear to stand. Many an eminent scientist has come unstuck in these situations. This is why science is conducted in writing, where claims can be tested and sources checked.

So when the Australian geologist Professor Ian Plimer challenged me to a face-to-face debate in July, I didn't exactly leap at the chance. His book Heaven and Earth, which purports to destroy the science of climate change, contains page after page of schoolboy errors and pseudoscientific gobble-degook. As the professor of astrophysics Michael Ashley wrote: "It is not 'merely' atmospheric scientists that would have to be wrong for Plimer to be right. It would require a rewriting of biology, geology, physics, oceanography, astronomy and statistics." But never, as far as I can determine, has Plimer responded to the devastating points made by his critics. He just keeps shifting his ground.

None of this stopped the Spectator from publishing a cover story promoting his claims. Plimer, the magazine suggested, has demonstrated that global warming theory is "the biggest, most dangerous and ruinously expensive con trick in history".

I wrote an article summarising what scientists have said about Plimer's claims and listing some of his obvious errors. In response Plimer requested a debate. Matthew D'Ancona, the outgoing editor of the Spectator, took up this cause, with a series of emails pressing me to accept (all the correspondence is on my website). At first, having seen something of Plimer's debating tactics, I refused. But then I realised that there might be a means of pinning him down.

I told Plimer that I would accept his challenge if he accepted mine: to write precise and specific responses to the questions I would send him, for publication on the Guardian's website. If he answered them, the debate would go ahead; if he didn't, it wouldn't happen. The two exchanges would complement each other: having checked his specifics, people at the public event could better assess his generalisations.

Plimer refused. After I wrote a blog post accusing him of cowardice, he accepted. I sent him 11 questions. They were simple and straightforward: I asked him only to provide sources and explanations for some of the claims in his book. Any reputable scientist would have offered them without hesitation.

But instead of answers, Plimer sent me a series of dog-ate-my-homework excuses and a list of questions of his own (you can read both sets on my Guardian blog). While mine address only what Plimer purports to know, his appear designed to be impossible to answer: they are less questions than riddles. Were you to take them seriously, every answer would require several years of original research. Gavin Schmidt, a senior climate scientist at Nasa, examined them and found that most were 24-carat bafflegab, while the rest had already been answered by other means. But that wasn't the point. Plimer's purpose appears to have been to distract attention from the fact that he can't answer my questions. Last Tuesday I offered Plimer a £10 bet that he could not answer his own questions. He has not yet accepted.

Having put up with this nonsense for almost a month, I gave him a 10-day deadline, after which I would assume that he had chickened out of our exchange and forfeited the debate. The deadline expired on Friday. Answers came there none.

There is nothing unusual about Professor Plimer. Most of the prominent climate change deniers who are not employed solely by the fossil fuel industry have a similar profile: men whose professional careers are about to end or have ended already. Attacking climate science looks like a guaranteed formula for achieving the public recognition they have either lost or never possessed. Such people will keep emerging for as long as the media are credulous enough to take them seriously.

What's odd is the readiness of publications like the Spectator to champion them. During my correspondence with Matthew D'Ancona, I asked what it is about climate change that makes intelligent people like him abandon all editorial standards. Why is he prepared to endorse Ian Plimer's claims, but not those made by people who contend that the entire canon of lunar science is wrong and the moon is in fact made of green cheese?

He replied as follows: "All you say may well be true, which fortifies my belief that a debate would be fantastic!" I pressed him again. "I think the answer," he replied, "may be that what I call mischievous – and it is part of the Spectator editor's job description to be mischievous – you would call deeply immoral and grotesquely irresponsible. The response to Plimer's piece – for and against – was passionate and cacophonous: exactly what I had hoped. Again, that may not strike you as an excuse. But perhaps it suffices as an explanation."

I told him that while the Spectator publishes noisy and provocative articles all the time, in most cases they are grounded in fact. This article was grounded in gibberish. So why climate change? Why is this issue uniquely viewed as fair game by editors who tread carefully around other scientific issues for fear of making idiots of themselves? And where is the mischief in doing what hundreds of publications and broadcasters have already done – claiming that man-made climate change is a myth? Surely to be mischievous you have to be original?

D'Ancona replied: "I can only speak for myself and say that, as an editor, I don't single it out for loony treatment." So I asked him for examples of loony articles he had published on other scientific matters. He replied: "Well, MMR for a start where I supported Wakefield initially!" But when Andrew Wakefield first suggested that the MMR vaccine is linked to autism, it was an original claim that, while unsupported, had yet to be debunked. Today we have 20 years of evidence, across tens of thousands of peer-reviewed papers, to show that people like Ian Plimer are talking out of their hats.

So Plimer won't provide his sources, and D'Ancona won't explain why he singled out climate change. But at least, after this frustrating episode, I have an answer to my questions: neither of them has a leg to stand on.