2011-04-17 07:00:53How to debate a climate denier
John Cook


Here is some advice on how to debate a climate denier. I may add and revise this post over time as additional thoughts and ideas come so feedback very welcome:

It's important not to get lost in scientific details - otherwise the audience is left swimming in a sea of "he said, she said" scientific details and they come away with the impression that there still is a scientific debate. This is not the narrative you want to leave. A key to debunking climate myths is not just explaining the science - you also need to provide an alternative narrative for the listener so they understand how and why the denier is misleading them.

Generally speaking, the alternative narrative I like to use is to clarify the difference between a genuine scientific skeptic and a climate denier. A genuine skeptic takes in all the evidence before coming to a conclusion. A denier refuses to accept any evidence that contradicts their preconceived views. When you debate a climate denier, reinforce this narrative.


For example, a denier says we can't trust the temperature record because weather stations are positioned near car parks, air conditioners, tarmacs, etc. Answer by saying they're denying all the evidence for warming. Satellites find the same warming trend as thermometers and there are no air conditioners in space. Ship measurements, ocean buoys, weather balloons, these all find the same amount of warming. We have tens of thousands of natural thermometers that also find warming - melting ice sheets, retreating glaciers, spring coming earlier every year, species migrating towards the poles, etc. The Greenland ice sheet isn't losing hundreds of billions of tonnes every year because someone put a thermometer near an air conditioner.

Another example. A denier says Climategate proves there's a conspiracy among climate scientists, who are trying to exaggerate global warming or hide conflicting evidence. Respond by reaffirming the narrative, to explain what the denier is doing. Every movement that denies a scientific consensus, whether it be climate change or the harmful effects of smoking or man landing on the moon, has something in common. They all indulge in conspiracy theories. That's because a scientific consensus is based on a preponderance of evidence. The easiest way to deny all the evidence is to avoid it altogether, by smearing climate scientists or thinking it's all a big conspiracy. That's what's happening with Climategate. The one question you never hear climate deniers ask is how has Climategate changed our understanding of the science? The answer is our understanding is as solid as ever. A few quotes taken out of context from a handful of emails do nothing to change the many lines of evidence for global warming.

Note the common pattern. Every climate denial argument is about denying the evidence, by avoiding it or cherry picking it. Don't let the debate devolve into your evidence versus their evidence. Instead, there is only the full body of evidence. In a sense, it's "what they say" versus "what nature is telling us". Of course, this requires you are well familiar with the evidence so when they hit you with cherry picked data, you can put it in the broader context and show how they're denying the full body of evidence.

How to counter a Gish Gallop

A Gish Gallop is when they throw a series of myths at you in quick succession. Don't try to answer all of them, that is futile and the listener is left swimming in details. Pick their most egregious error or that one myth that you can turn into a teachable moment. Debunk it by explaining how that climate myth misleads (usually by cherry picking). That way, you educate people about science but just as importantly, you reinforce the narrative that climate deniers are denying the evidence

Further reading

It's helpful to familiarise yourself with The 5 characteristics of scientific denialism - read the blog post then read the paper it's based on, Denialism: what is it and how should scientists respond? (Diethelm & McKee 2009).

Of course, essential reading is Climate Change Denial: Heads in the Sand (Washington & Cook) :-)

You have better traction with your audience if your explanations are simple and clear. The best way to explain complex scientific concepts to a lay audience is through metaphors. There's a forum thread on useful climate metaphors - stocking up on these ideas has helped me when trying to simply explain climate.

2011-04-17 18:41:41Recognising the deniers' scripts
James Wight


I agree with all of your advice, John. Of course, it’s not always easy to give the optimal response in the heat of the moment.

As I’ve mentioned before, the deniers have a script that they want us to follow, and when we try to set the record straight by explaining the facts, we run the risk of conforming to their script. The deniers have a number of scripts – “he said, she said” is perhaps the most obvious.

For example, when deniers claim the surface temperature record is biased by the urban heat island effect, one response is to explain that scientists correct for the urban heat island effect. A better response in my opinion is to emphasize the many independent lines of evidence supporting global warming. The former response plays into a number of the deniers’ scripts:

  • The “he said, she said” script, obviously. One speaker says UHI is a problem, the other says it’s not. The science is not settled! Who do I believe? Most likely the person who confirms my prior beliefs. Deniers only have to succeed in confusing the public to win the debate by default.
  • The “nail in the coffin” script. When a denier uses, for example, the UHI argument, they implicitly assume that if they can take down the surface temperature record, they’ve disproved global warming. Responding by defending UHI corrections only reinforces that impression. (Another example: when a denier attacks the IPCC for making an error, they implicitly ignore the long list of other scientific organizations who agree with the consensus.)
  • The “circling the wagons” script. We think scientists can do no wrong. We think the data is perfect. We’re playing defensive. The deniers put the burden of proof on us to prove that the scientists are innocent. (This is why my Climategate rebuttals, though they had to set the record straight, also focused on putting the emails in context.)
  • The “hiding the decline” script. Scientists adjusted the data? FRAUDS! A bunch of inquiries cleared the CRU scientists? It’s a TRICK! You can’t trust any of them because they’re lying for their AGW faith!

A couple of others to be aware of, which don’t apply specifically to the UHI argument:

  • The “shutting down debate” script. We’re Stalinists who want everyone to tow the party line. Dissent will not be tolerated! The debate is over! The deniers employ this script to demand airtime. (We’re always accused of this whenever we mention scientific consensus – I guess we can’t do much about that except try to explain that it represents the best information we have at the moment.)
  • The “error-ridden” script. You make one mistake? Then we can disregard the other 1,000 pages of your report, all your peer-reviewed papers, all your blog posts, etc.
  • The “guilt by association” script. We can also throw out everything published by anyone else who’s ever corresponded with you.
  • Maybe someone else can think of other such scripts (they don’t have to be specific to UHI; I was just using that as an example).

We can’t afford to let the denialists determine the terms of the debate, otherwise they achieve their aim of merchandising doubt. We must try to depart from their scripts – easier said than done, but recognizing the scripts is a first step. It’s all a rhetorical game to them – we’re limited to inconvenient truths; they tell convenient lies.