George Monbiot writes on ZNet, May 12:

Request for Climate References
People who deny that manmade climate change is taking place have this in common: they do not answer their critics. They make what they say are definitive refutations of the science of climate change. When these refutations are shown to be nonsense, they do not seek to defend them. They simply repeat them as if nothing has changed, then move on to another line of attack.

What else can they do? If they have no understanding of science and no means of supporting their claims, they must seek to distract their critics with a barrage of new allegations. It doesn't matter where they might be placed on the political spectrum—whether like James Inhofe and Joe Barton they come from the hard right or, like Alexander Cockburn, they come from the left. The tactic is always the same: never apologise, never explain. Just raise the volume, keep moving, and hope that people won't notice the trail of broken claims in your wake.

Two weeks ago Alexander Cockburn maintained, in an article written for The Nation and reproduced on Counterpunch and Znet, that "there is still zero empirical evidence that anthropogenic production of CO2 is making any measurable contribution to the world's present warming trend." He claimed to have demonstrated a disjunction between the carbon dioxide emissions produced by human activity and carbon dioxide concentrations in the atmosphere, which made it "impossible to assert that the increase in atmospheric CO2 stems from human burning of fossil fuels."

His source for these extraordinary claims was a man he met "on a Nation cruise back in 2001", whose qualification, apparently trumping the tens of thousands of years of collective experience of the world's climate scientists, was that he had once trained as a meteorologist. Cockburn provided no references for the "papers" he said this man had written: we simply had to take his word for it.

On the website realclimate.org, the eminent climate scientist Michael Mann quietly demolished Cockburn's claims. It wasn't hard to do: he had made a concatenation of basic scientific mistakes, and appeared to be unaware that there is, indeed, empirical evidence that anthropogenic CO2 has contributed to the world's present warming trend, and that the increase in atmospheric CO2 stems from human burning of fossil fuels (see www.realclimate.org).

Two days ago, Cockburn responded. Or didn't respond. In a new article for The Nation, he repeated his assertion that "there is still zero empirical evidence that anthropogenic production of CO2 is making any measurable contribution to the world's present warming trend." He provided neither new evidence to support it, nor a refutation of the evidence which contradicts it. He must be aware of Michael Mann's critique—how, after the correspondence he has received on this issue, could he fail to be? Indeed, for the first time in his writing, Cockburn mentions Mann by name.

But rather than responding to Mann's arguments, he simply accuses him and James Hansen, the head of space studies at NASA, of being "fearmongers". This is an unfortunate choice of targets: both men have been subject to Congressional questioning which could fairly be described as McCarthyite. They have been attacked by people with whom Cockburn should blush to be associated. Not only did they survive this ordeal of fire; they walked out triumphant. Unlike Cockburn, they have answered their critics and seen them off. Their work has been vindicated by dozens of further studies.

But he must keep moving, firing his Parthian shots as he goes. Concern about global warming is a "conspiracy of interest between the Greenhouser fearmongers and the nuclear industry". The Intergovernmental Panel on Climate Change is an "army of functionaries and grant farmers, and the merest sprinkling of actual scientists", whose science is less reliable than Lombroso's craniology. Don't stop. Don't look back. Don't let your opponents draw breath.

It is racy and entertaining, but it is pure distraction. Cockburn continues to rely on an argument which he cannot defend. At what point will he acknowledge this? At what point will he answer his critics? At what point will he stop making claims which he knows are false?

Though I am not a climate scientist, I too presented him with a challenge last week. It should have been much easier to answer than Mann's challenge: provide your references. Cockburn claims to have based his argument on "papers" produced by the man he met on the Nation cruise. If he has any knowledge of science—I mean any knowledge whatsoever—he must know that a scientific claim carries no weight unless it has been published in a peer-reviewed scientific journal. Publication does not mean it is correct, but it does mean it is worth debating. Where were these "papers" published?

Scientists in the United Kingdom sometimes satirise people who claim to know more about their own subjects than they do by imagining how they would respond if asked to provide their references. "Man I Met in a Bar, A. 2006. Why I am Right and Everyone Else is Wrong. Proceedings of the Inebriate Society, Vol 9991524, no4." So far, Alexander Cockburn's references amount to "Man I Met on a Ship, A. 2001." If he has better sources than that, why won't he reveal them?

I repeat my challenge. Provide your references, or admit that your argument has no merit.

www.monbiot.com

[Editor's note: This is a reply to Cockburn's second article on climate politics and climate change, which, while it did not directly respond to Monbiot's or Mann's first reply to Cockburn's original article, did mention Mann by name.]

See our last posts on global climate destabilization and Alex Cockburn.