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On the value of consensus in climate communication

Posted on 23 May 2013 by John Cook

After our Consensus paper was published with extensive media coverage, law professor and climate communicator Dan Kahan posted an emotive blog post (he characterised it as a "haughty outburst"). He questioned the value of a study measuring consensus and whether consensus is something climate communicators should be emphasising.

Once Dan had a chance to calm down, we corresponded about his post and he suggested he summarise his views in a 4-point article that I could respond to. Dan's 4 point critique of Cook et al. and my response have now been posted on his blog. He also included a response from science journalist Scott Johnson. I recommend you head over to Kahan's blog post summarising all three viewpoints, but here are a few choice excerpts.

In his four points critiquing Cook et al. (indulge me in a paraphrase), Kahan questions how much scholarly value there is in our paper, suggests that the reason for the consensus gap is not a lack of information but cultural and that consensus messages can be polarizing. Here are a few excerpts:

The Cook et al. study, which in my view is an elegantly designed and executed empirical assessment, doesn’t meaningfully enlarge knowledge of the state of scientific opinion on climate change.


That message—that there is a scientific consensus on climate change—has been the centerpiece of climate-science communication for over a decade. There have thousands upon thousands of stories in the media reporting this contention. The divided state of U.S. public opinion hasn’t changed.


Second, I think a science communication strategy that makes “getting the word out” on scientific consensus can easily aggravate the antagonistic cultural meanings that generate polarization.

In my response to Kahan's criticisms, I outline some of the scholarly contributions of our paper (there are plenty, IMHO), demonstrate with my own research how the consensus gap is a product of lack of information *and* cultural bias, explain how the consensus gap has persisted despite consensus being "the centerpiece of climate-science communication for over a decade" and look at research linking perception of consensus with support for climate policy. Here's some excerpts including a nifty new graph (if you're going to say I excerpt my own content more extensively than the others, well, guilty as charged):

The following graph plots perceived scientific consensus from a survey of a US representative sample versus support for free markets (-1 is equivalent to extreme liberal and 1 is equivalent to extreme conservative). I’ve included a green dotted line indicating the 97% consensus (I can never resist adding some bling to my graphs).

Several features jump out from this data. We confirm recent studies and public surveys that find a significant relationship between perceived consensus and free market ideology (p < .00001). Also, it’s hard not to notice the sharp drop in perceived consensus for participants with very strong support for free markets (e.g., extremely conservative).

However, the key feature for the purpose of this discussion is that even for liberals, there is still a large gap between perceived consensus and the 97% reality. This indicates that there is still a significant lack of awareness of consensus, even among those whose cultural values are predisposed to agree with AGW.


If the public have heard ‘over & over & over that there is "overwhelming scientific consensus" on AGW’, then why is public perception of consensus so low, even among liberals? A significant contributor is a focused and persistent misinformation campaign designed tomanufacture doubt. Science communicators are not operating in a vacuum but competing in a marketplace of ideas.

As early as 1991, Western Fuels Association spent $510,000 on a campaign to “reposition global warming as theory (not fact)”. The infamous Frank Luntz memo urged Republican politicians to “…make the lack of scientific certainty a primary issue in the debate.”  In an analysis of syndicated conservative opinion pieces, the most popular myth was “there is no consensus”. Lobbyists sought to undermine Obama’s climate policy by attacking the consensus, arguing “If we win the science argument, it’s game, set, and match.”

 It’s becoming increasingly apparent that attacking the consensus has been a central strategy of opponents of climate action.


A key point that mustn’t be overlooked is that two studies (Ding et al 2011 and McCright et al 2013) have shown that perception of consensus is linked to support for climate policy. When people understand that climate scientists agree on human-caused global warming, they are more likely to support climate action.


This is not to say that consensus is a magic bullet that will solve all our problems and usher society into an environmental utopia. If only things were that simple! But by reducing the consensus gap, we are removing a significant roadblock to public support for climate action.

Lastly, Ars Technica science journalist Scott Johnson also submitted a response to Kahan's criticism of Cook et al. Here are some excerpts:

That brings me to the charge that if informing about the consensus was worth doing, it would have worked by now. (“Worked” here meaning a large shift in public opinion, I assume.) I can’t categorically agree. Einstein’s definition of insanity may have been “doing the same thing over and over and expecting a different result”, but in the business world, this behavior also goes by the name of “marketing”. (To some extent. It’s a stretch—just humor me.)

Repetition of a message can be beneficial. I could be wrong, but I’m not completely sold on the idea that all members of the public have received plenty of information about the scientific consensus before.


Dan has agreed, I think, that information about the scientific consensus is important, so shouldn’t we be arguing about how to communicate it rather than whether to communicate it? If this story is really a waste of time, isn’t it the fault of the journalists who covered it poorly rather than the study itself? If the argument is that this study represents no value-added over previous ones, I think it’s at least the best study to date. (The tremendous transparency alone makes it valuable.) If so, its newness represents a news hook and a communication opportunity, which is why I felt it was important to cover it.


It’s my feeling that “preaching to the choir” should get more respect. We’re worried about issues on which public opinion is out of sync with the existing science, so we’re naturally focused on the dissenting side of the opinion spectrum. I don’t think the concurring side of the spectrum is irrelevant.

One thing we all agree on is that the consensus message won't fix everything. It's not a magic bullet solution - closing the consensus gap is simply about removing a roadblock to climate action. I also agree with Scott that the issue is not whether we should communicate consensus but how we should communicate it. And that is an area of open research.

Check out all three responses in full at Dan Kahan's blog.

Note that a high-rez version of the graph of perceived consensus versus free market support is available in our collection of consensus infographics, which are all creative commons licensed and free to be reused.

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Comments 1 to 10:

  1. I don't have much to say.  Kahan's points are fair, but they're also academic.  No actual model for communication is given, other than a link to a page that has, near the bottom, something useful--the ambivalent partisan approach or mode.  Cook makes good points as well, but he's responding to a game being played behind the curtain, one that Kahan never really addresses.  Indeed, that game should be fully recognized in any strategy for moving the public on this issue.  The other players are trained in rhetoric and have absolutely nothing to lose.  It's as if they play the game with a full deck and science is limited to no face cards (and aces count as 1). 

    Detailed, practical approaches need to be available to anyone who is willing to enter "the trenches."  The "ambivalent partisan" mode is one I try to emulate, with a few additions.  More powerful than ideology is the need to remain valuable, and that need is amplified when the discussion is public.  No one wants to be dismissed out of hand--to be categorized, labeled, boxed, stamped as innocuous.  I will only once in a blue moon use any sort of label, including "denier," when I speak with people in a general public forum on this issue.  I ask questions, and not questions that have a rhetorical edge, but well-explained questions that invite the interlocutor to express a speculative opinion.  No ivory tower.  I try to give uncertainty when it exists.  It's better to provide and discuss uncertainty than it is to leave it out.  Tom Curtis is very good at that, and I think to the consternation of a few other SkS regulars.  Also, as Kahan points out with the example of Hayhoe (though he gums it up with academic jargon), it's better to step into someone's else's castle and recognize it as a valid construct than it is to remain in your own castle and stand at the battlement throwing taunts and unexplained bits of heavy science.  I've had good success with this general approach (a variety of private FB messages/emails thanking me not for explaining things but for doing it in a way that wasn't antagonistic.  I often get the "I'll respond to you because you seem like a reasonable person."  That's the response I aim for.).

    Ultimately, the Cook study is only valuable to me as a conversation starter and a casual debunking of the "there is no consensus" myth.  I think Kahan doesn't understand that there are a great many people who don't understand the greenhouse effect and who are susceptible to suggestions that AGW is something different than the greenhouse effect.  That's really what the consensus is all about for me as I find myself discussing it in various places.  People aren't sure what points of the theory the consensus is providing agreement on, and so they respond to it as they do to every other article talking about global warming.  In other words, the consensus doesn't mean anything specific.  It's like how the word "catastrophic" is used in professional "skeptic" circles--it means whatever you need it to mean at the moment.

    A bit rambling.  Sorry.  I started out with my two cents and it turned into a pfennig, a pence, and half a yen (to revise it).

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  2. I do believe the main problem for many now is not to accept that there is global warming happening, but that its caused by humans - as it implies that they are themselves guilty of it. Also, its very easy for people to put blame to others even if they believe humans are the cause of it. "Its the Chinese and all their coal plants!". So here in Norway there is constantly comments from people about e.g. electrical cars being bad because they are fueled by coal electricity - even though Norway has 99% of its electricity from hydro power. The general idea is that, if its not good for the general average over the whole globe, its not good for us as well. But this idea is rather silly in my opinion, and in most cases its rather impossible to change peoples view on this since its so securely rooted in the trandition of the fossil fuel car being the best choice. It doesnt help that Norway also gets its current wealth from oil as well.

    The same odd argument is also used against building more windmills in Norway, because we already have enough hydro power. So its indeed like a snake biting its own tail, as many people seem to be unable to have more than one thought in their heads at one time. I do believe the more you are able to see things in a wider perspective your views will slowly creep towards more liberal viewpoints and are able to see the bad things about free market policies and the effect of e.g. globalism. Also there is general disconnect from nature in the way that we treat consumables as things that magically appears in the shelves. In general people need to be educated about the carbon footprint of anything we buy, almost to the point where every good has a carbon footprint estimate printed on its label. But with e.g. the clothes industry not even wanting to inform the public about which factories their goods are made in - its clear that the "truth" of globalism is one they would rather be kept secret since its generally bad publicity the moment another building collapses or is known for using child labour. So we need education of the masses that every choice we make in consumption is also a moral choice about the implication of globalism, its carbon footprint and human suffering that results from it.

    I am very thankful that John Cook and SkeptialScience is keeping up with spreading the message and I was very happy to see the consensus research even presented in mainstream media here in Norway as well. The discussions in the comment fields were just littered with "AGW is BS" and all kind of denial ofc. But those comment fields are also a place were we should be active and promote real science information and preferably with links to sources, which is one the denialsphere often lacks as its generally based on feelings and not facts. Unfortunately when they do seek "facts" for themselves they very easily end up on WUWT and other denial sites because it seems they have been able to flood the search databases with classical spam link methods for getting high on the search results. Its easy to see this if you search for "global temperature" for images and see where those images lead to. So its indeed an information battle going on here to get real information. Good transparent research like this consensus project is definitely what we need more of.

    To quote a song by Peter Gabriel: "Turn up the signal, wipe out the noise!".

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  3. I think this statement by DSL @1 is thought-provoking, and so I am going to take the liberty of plucking it out and repeating it, lest it get lost. It's only human to quickly skim through a multi-paragraph comment and maybe miss a gem like this:  

    "More powerful than ideology is the need to remain valuable, and that need is amplified when the discussion is public. No one wants to be dismissed out of hand--to be categorized, labeled, boxed, stamped as innocuous."

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  4. DSL, I noticed you mentioned FB - do you post a lot about AGW on your own timeline?  If so, what has been your experience with the result of it?  

    In my case, I have been posting something about AGW impacts, green tech/policy developments on my timeline just about every weekday for the past several months (sometimes reposts from here, sometimes from David Roberts at Grist, sometimes from RenewEconomy, etc.).  I think it results in some of my closer friends who are not "skeptics," but just aren't as independently interested in the subject as I am, reading more about AGW than they otherwise would because they see on their "news feed" that I posted something.  Another effect is that a couple of my FB friends who are "skeptics" or "lukewarm skeptics" occasionally comment on my posts or even post their own links on my timeline, leading to discussions that my other friends often follow and chime in on.  I don't think I've made a tremendous impact on the "skeptics."  The closest thing to progress from a "skeptic" friend of mine was when he first posted (in his own WordPress blog) a reference to global warming as a "specious concept," and then in a later post of his musings on the theme of devoting our attention to the problems of the day, stated that for example he could donate to a global warming awareness organization, but he is "not convinced that climate change is a legitimate issue."  

    Going from proclaiming AGW as a "specious concept" to being "not convinced" is arguably some movement.  But what mainly motivates me to post on FB is to use my timeline as a kind of "information hub" for the benefit of my friends and for my own benefit as well - I have a kind of half-baked organization scheme where I sometimes post related articles in the comments to a a previous article, for later reference...  

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  5. One only needs to see how often the consensus is brought up as an arguing point by those in denial to know that this new paper has great value when it comes to the politics of climate change.

    But clearly it's neither here or there when it comes to the work of climate scientists trying to pin down the likely outcomes of steadily raising the planet's atmopheric CO2.     

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  6. jdixon, I rarely post intentionally on my wall.  Occasionally, I'll be on a thread somewhere and it will show up on my wall.  I want to be very careful with the friends and family I've allowed on my FB.  The best opportunities are when a friend of a friend makes an unscientific comment and I see it on the home stream.  I feel no resistance to correcting the person, and it keeps the friend in observer mode.  If the friend wants to discuss it, no problem.  I look for situations where I can start conversations.  It's very difficult, though, to keep the baseball bat that is the published science in my back pocket.  However, I sober up when I think about how insulated my friends are.  Most have not had a liberal education that has allowed them to stand back from it all for several years.  For most of my friends, I can read their opinions in the content of CNN and FOX.  That's not an insult; it's a reality.  FB is a liberalizing force, though.  The more contact we have with each other's brains and cultural situations, the better.  It is easy to de-friend, though, and that's why I walk softly, most of the time.

    The family is another matter.  My family (up-tree) is small and dying.  My in-laws are large and growing.  And stereotypically Southern (US) for the most part. Some will say one thing in conversation and then whisper something else behind the back.  It's very annoying to someone who likes and encourages transparency of thought.  I've had my sit-downs on climate with a few of them, the mother-in-law in particular.  Again, though, anger is of no use.  It often takes years for evidence to begin to change belief.  Fortunately, my sister-in-law is heavy into sustainable living and community development.  They think she's flaky, but she's cute and funny so they tolerate her "wierd side."  We do occasionally do FB team-ups with family members when they get too obnoxious.

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  7. I'm wryly amused by this little spat, because all the protagonists seem to be operating in the famously closed world of academia - a gentle accusation that is characterised by the comment that the study "doesn’t meaningfully enlarge knowledge of the state of scientific opinion on climate change". My rebuttal to that point is that for those who do climate science, or study it from a lay perspective (e.g. me), scientific opinion is irrelevant to the actual science. There are no planks to my own arguments with contrarians that depend on opinion (wheras nearly all contrarian arguments are not only opinionated, but usually stated as fact). 

    My arguments depend in their entirity on published papers, the experiments designed to test them, and the evidence that supports them (plus the consilience of climate science with other disciplines, and with the foundational science on which it rests, and with which it must conform). 

    Yet this study is really important in my view, and to support that view I need to ask that we step out of the scientific community, and into the wider world. On arrival, we might find something disconcerting: while it would be nice to think that the issues we're discussing are about science, in fact the issue is something else entirely, something grubby and distasteful, something that I have found scientists and activists are very reluctant to engage with, and that is propaganda.

    We are at war. We didn't want it, but it was forced on us, by those who cannot or will not embrace the implications of the science, and by those whose interests are threatened by those implications i.e. fossil fuel companies. Since the demagogues have no science to back up their arguments, it is necessary to find other weapons with which to wage war, and these weapons are stamped out of molds all too familiar: attacks on credibility and probity, insinuation, misrepresentation, demonisation, conspiracy, and implied or asserted furthering of vested interest. These are the weapons of the ideologue, and what this study does is put an equivalent weapon in my hand - one I have no hesitation in pointing at the enemy, because I recognise that there is good propaganda as well as bad, and what little I contribute is, I hope, of the former kind. It certainly isn't science.

    It is also important to understand where this battle is being fought. It is taking place in the media; the paper itself demonstrates that it isn't taking place within the climate science community. And it isn't scientists waging this war - at best, I think scientists feel co-opted, as if they've been caught up in a bar brawl when they were just trying to get a glass of water. Reading Kahan's remarks, there is a sense of frustration and annoyance which he acknowledges, but frames in terms of some putative failure on his part, or on the part of those trying to improve the communication of science. This misses the boat: science will never, ever, convince the public to support political and economic measures to mitigate or adapt to climate change. They don't get it, don't get the compelling probabilities, don't get the causal chain, don't get the timescales or the rapid development, which often appears contradictory or equivocal.

    What the public do get is propaganda. They may not recognise it as such, but so powerful is the effect of the constant repetition that the public discourse is blighted and twisted out of shape, where black really can be made to appear white, where there is no nuance and no shades of grey, and where there is no such thing as a fact. And in this petty war, one of the facts most open to attack is the consensual nature of climate science, for the 'unsettled' science is, as John points out, not only Luntz's weapon, but that of the tobacco industry before it, and perhaps more emotively, the principle tool of the National Socialists in the 1930s. I won't repeat Goebbel's aphorism about propaganda, but I will point out the consistency between his application of it, and that of all ideologues who followed, of which Luntz is just one more professional liar.

    This is a very old debate: when does the means justify the ends? Previously, I've identified the problem as the 'Bomber Harris' paradox. Harris ran the RAF's Bomber Command and is held responsible for either shortening the war by firebombing German cities, or for destroying the moral credibility of the Allied forces by being as inhuman and evil as the Nazis. This debate carries echoes of the same issue: the denial brigade lie all the time, so we find it incumbent to be truthful. Deniers never admit mistakes, so we have to (as SkS did, bravely, this week - and of course got pilloried for it - was this honesty successful if success is measured in propaganda terms?).

    So there's the paradox: while science continues on its quiet course through the long days of number crunching and patient gathering of information, there is a dirty war raging outside. Scientists don't want to be like Harris, don't want to tool up and start burning stuff, and good job too. Leave the dirty work to the soldiers, but don't think this war will be won by science, by evidence, or by banging on about the consensus, for this paper is nothing more than our missile shield, our Patriots, our counter-intelligence. It's purpose is to sabotage the enemy's propaganda, and for that I'm thankful because I'm very short of effective weapons when science and evidence don't work. 

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  8. Good comments! Definitely worth drawing attention to the strength of agreement amongst scientists but it does sound like careful consideration of the language used is necessary, so better call it something other than a scientific consensus!

    Is it of any value to put the 3% under the scope -or would that simply give them a platform in which the "stick to the facts and don't leave out the provisos" scientists will face opponents that have impose no such restrictions or boundaries on their rhetoric? Against the experienced debater, who can argue as effectively that black is white and that 2+2=5 as argue the contrary, we need experienced debaters who can enter the fray, boots and all.

    Whilst this effort to examine the consensus amongst scientists, I think what I would like to see is more effort along a different tack - a greater focus on our peak science bodies and on the role they have played in providing independent expert assessment of climate science, it's methodology and results.

    I'd like to see a starting from scratch rerun of that process, but with as much televised fanfare as possible - a look at the Royal Societies and Nation Academies, what and who they are and what they do, who picks the panels/committees and on what basis, a look at the members of those panels - both to highlight their credentials and how they've distinguished themselves - and to humanise them. And to show that these are people who have no personal axe to grind, are above any kind of group think and who will not be swayed by anything but the evidence at hand.

    Whilst that might be another way to persuade the public of climate science's bona fides, I think the most important audience has to be those who hold positions of public trust - our elected and appointed representatives. ie the ones who have been recipients of government commissioned scientific reports and advice but have been choosing to dismiss and ignore:-

     Whilst the public has some right to their own opinions, those representative do not. Even if it's populism without responsibility that puts them there, once they are, they do have a greater and wider responsibility - to the entire community, not just those who backed their election. For them to endanger our future by wilfully ignoring government commissioned expert advice is a betrayal of that wider trust and responsibility.

    Too many of our office holders have been lending climate science denial an air of respectability it has not earned and for those interests who want to obstruct strong climate policy, that high level support from skilled and persuasive speakers in positions of influence is (IMO) a more powerful influence over the scope and the tone of the public debate; 97% won't persuade the public if that 97% can't persuade a clear majority of those who hold positions of trust and responsibility on the public's behalf.

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  9. Correction to para 3 of my comment above - "Whilst this effort to examine the consensus amongst scientists is important and valuable..."

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  10. Anyone who has any doubt about the practical utility of Cook et al should consider that the Australian conservative opposition leader, Tony Abbott, has used ambiguity about a scientific consensus to publicly question the very existence of climate change.  Many of his senior (and junior) party members, and a number of high-profile conservative media commentators, are even now at least as inclined to use this stratagem to stir up public doubt.

    This action was one of several that were employed by conservatives and that led to a very significant delay of action in Australia in addressing the effects of human emissions.  It has in fact effectively tainted the political landscape of Australia since 2010, when its consequences amongst the general public contributed significantly to Kevin Rudd shying away from action and Julia Gillard grasping the reins from him.

    The next (and already evident) approach by the conservatives will be to acknowledge that climate change is happening, and that it was accepted by a consensus of scientists, but that it is not nearly as dangerous as scientists are warning.  It's just the next gambit in the list of denialist responses that many of us have been discussing for years.  A useful follow-up to Cook et al would be to conduct a similar survey investigating scientific understanding of and thoughts on the full spectrum of consequences and impacts of human-caused climate change.  Last year in an idle moment I even sketched an outline for such a survey, including questionaire design and methodological rationale and approaches such as stratification for professional and personal cofactors.

    Now that would be a study that would be of great interest to me, and no doubt to many others...

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