Lessons from the Monckton/Plimer debate

Earlier today, I attended a climate debate between Ian Plimer and Christopher Monckton versus Barry Brooks and Graham Readfern at the Hilton Hotel in Brisbane (many thanks to Graham for the ticket). The debate made for good entertainment, and surprisingly, I even learnt a thing or two about the climate debate. Even more surprisingly, the most enlightening aspects came from Monckton and Plimer.

Monckton kicked off the debate, warming up with a few disarming jokes. The man sure does know how to work a crowd. He then informed us that he was to focus on the most important aspect of climate discussion which is climate sensitivity. Unfortunately, he immediately veered off-topic, spending most of his allotted time taking potshots at the IPCC. The discussion of climate sensitivity came in a hurried blur at the end of his presentation, including a curious graph that showed solar activity increasing over the last few decades. As direct measurements of solar activity show solar output decreasing since 1980, I was interested to see where his data came from but the graph was gone before I could locate the reference.

Ian Plimer jumped out of the gates with the (correct) assertion that climate has changed in the past and has experienced quite dramatic changes in temperature. Indeed this is Plimer's chief refrain in his book, in every interview I've heard and at today's debate. Anticipating this (correctly), earlier in the week, I'd submitted a question to be asked of Plimer during the question time that took up most of the debate time. My question was:

"You say climate always changes and climate scientists ignore this. Why do you ignore the dozens of studies that examine past climate change? These actually provide evidence for our climate's sensitivity to CO2 forcing."

Okay, it's a mouthful but I've been genuinely wondering this since I read Plimer's book. He's a qualified geologist, a professional scientist and yet he seems unaware of (or ignores) the extensive body of peer reviewed literature that acknowledges past climate change, scrutinises these periods and concludes that our climate is sensitive (for a good overview, read Knutti & Hegerl 2008). Those periods of dramatic change demonstrate that our climate is subject to net positive feedback. Doesn't Plimer realise when he talks about past climate change, he's citing evidence for high climate sensitivity?

So I was understandably eager to hear Plimer's response. He began by claiming 'those studies' were based on recent observations and didn't cover the deep past. He then rambled about limestone sequestration of carbon dioxide. The question dodge was disappointing. Not entirely surprising, considering past form, but nevertheless disappointing. Perhaps if I'd cited Dana Royer's study of climate sensitivity from the last 420 million years of temperature change (Royer 2007), I may have received a more specific answer. But I only had a few lines in which to squeeze a question.

Still, I must tip my hat to Plimer and Monckton. Both utilised their formidable public speaking skills and rhetorical flourishes to persuasively explain why humans can't be causing global warming. Plimer's argument was that climate has changed in the past. Eg - climate has a high sensitivity. Monckton's argument was that climate has a low sensitivity. I think the irony that the two were arguing contradictory positions was lost on most of the audience.

In a sense, their combined approach perfectly encapsulates the way skeptic arguments are used to mislead. Layering argument upon argument, regardless of a lack of internal consistency, isn't about furthering scientific understanding but proving the preconceived notion that humans can't be causing global warming. Two skeptic arguments can contradict each other, even on the same debating stage, so long as the common enemy of man-made global warming is refuted.

Posted by John Cook on Friday, 29 January, 2010

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