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Ask Me Anything about Climate Science Denial

Posted on 7 May 2015 by John Cook

The good folk at edX (who host our online course Making Sense of Climate Science Denial) generously organised a Reddit AMA (Ask Me Anything) for me this week. The AMA was scheduled to start at 7 am here in Brisbane. When I woke up at 6 am and loaded the AMA webpage on Reddit, 2000 comments had already been posted! So I gulped down a coffee and in the short time available, belted out as many answers as I could as quickly as possible (while linking to relevant videos from our MOOC). Here are a selection of my answers, grouped into categories:

Psychology of climate science denial

Q: What are the main reasons someone would deny climate change?

A: The main driver of climate science denial is political ideology. Some people don't like the solutions to climate change that involve regulation of polluting industries. Not liking the solutions, they deny there's a problem in the first place. A number of empirical studies (including my own PhD research) have found an extremely strong correlation between conservative political ideology and denial of science. And randomised experiments have demonstrated a causal relationship between the two.

This is extremely important to understand. You can't respond to science denial without understanding what's driving it. We examine this in Scott Mandia's lecture

Q: Do you think the psychology behind climate science denial can also explain other types of science denial?

A: A general principle is that people reject scientific evidence that they perceive threatens their worldview. So while different factors drive denial of different areas of science, often you will find the mechanisms are similar. For example, religious ideology drives rejection of evolution science in similar ways to political ideology driving rejection of climate science. Another thing that different types of science denial have in common is they all share the 5 characteristics of denial, as examined in this video from our course:

Q: How can you tell the difference between willful ignorance (or maybe not ignorance but disagreement) based on an agenda, and legitimate disagreement based on really misunderstanding data, or surface level policy disagreement?

A: This is an excellent question and I address it in my lecture on the 5 characteristics of denial:

It's very difficult to tell the difference between intentional deception (disinformation) and genuinely held misunderstandings (misinformation). My lecture explains how the characteristics of denial - cherry picking, logical fallacies, conspiracy theories - can arise from psychological bias. So intentional deception looks much the same as when someone is deceiving themselves through psychological bias. 

Q: Can you talk a little about confirmation bias, cognitive dissonance, the backfire effect, and how to overcome people's deeply held beliefs?

A: Science denial is confirmation bias on steroids. When we receive scientific evidence that we perceive threatens our worldview, we experience cognitive dissonance - the sensation of two conflicting thoughts/feelings. Do we abandon our worldview that we've held all our lives and that comprises our identity and binds us to our community, or do we reject that scientific evidence we just encountered. Seems a pretty clear choice, right? That's what's going on under the hood when people deny scientific evidence. It can even cause people to reinforce their beliefs, bolster their pre-existing attitudes - in response to conflicting evidence. This is the worldview backfire effect.

There is research indicating that if scientific evidence is presented in worldview friendly ways, from messengers who share the values of the recipient, then the scientific evidence at least has a fighting chance. But I believe our efforts are better spent on the much larger majority who are open to scientific evidence, rather than banging our heads against a brick wall trying to persuade the unpersuadable.

Q: Why do lukewarmers seem to always side with outright deniers? Shouldn't people like Curry, Pielke Sr. and others spend just as much time (if not more) criticizing those who claim AGW isn't happening, or is a hoax? Doesn't that simple fact invalidate their position?

A: There are three stages of climate science denial: denial of the existence of global warming, denial of the causation of global warming and denial of the research into climate impacts. "Lukewarmers" fall into the latter category. So when lukewarmers say "I don't deny the science", they may accept that humans are causing global warming but they are still rejecting inconvenient scientific evidence. Denial of scientific research into climate impacts is still climate science denial.

What all three types of climate science denial have in common is they all lead to the same conclusion - arguing against climate action. This is why those in denial about climate impacts rarely criticise those who deny global warming - they both have the same end goal in mind.

Scientific Consensus

Q: Do you honestly believe that science should just be done by consensus?

A: I believe our scientific understanding should be guided by the full body of evidence. If you're interested in my full views on the roles of evidence and consensus, I recommend watching the first three lectures of our course:

Or better yet, enrol at where not only can you view the videos, you can also engage with our interactive activities and discussion forums.

Q: Do you adhere to Karl Popper's philosophy that in order to make a valid scientific statement, it needs to be possible to disprove the statement. If so, what type of data or piece of evidence would turn you into a climate skeptic?

A: Science does need to be disprovable, that's what distinguishes it from pseudoscience. What would turn me into a climate skeptic? I already am a climate skeptic because skepticism is a good thing - skeptics consider the body of evidence before coming to a conclusion (sorry, I know that's just semantics but it's an important point). But what would convince me to reject human-caused global warming? The answer is simple - provide an alternative explanation that both fits all the human fingerprints listed above and rules out greenhouse warming.

Q: With regard to your infamous 97% study... why were you so resistant to releasing your data for review?

A: On the day our 97% consensus paper came out, we also released data of the final ratings given to every paper in our analysis. But most importantly, we also created an interactive webpage that allowed the public to replicate our analysis. We were keen for people to go through the same process we went through - read all the climate abstracts and experience the breadth and depth of scientific research into climate change. So I find it extraordinary that people complain about our data release when we actively encouraged people to replicate our results. The interactive rating page is at

However, as researchers, we also have ethical obligations to protect the confidentiality of participants in our research. Consequently, we did not and will not release data that violates the privacy of participants. This data isn't required whatsoever to replicate our research.

So again, I strongly encourage everyone to visit and try to replicate our rating process. Compare your ratings to ours. Read the climate research. Or even better, attempt to conduct your own independent analysis, quantifying the degree of scientific agreement on human-caused global warming. It's significant that amongst all the critics of our consensus research, and there are many, not one has published an independent analysis quantifying the level of consensus.

Q: Are there any scientific studies or strong arguments that you consider legitimate critisism on the current consensus in the scientific community on anthropogenic global warming?

A: I'm not aware of any legitimate criticism of the consensus that humans are causing global warming. To legitimately cast doubt on human-caused global warming would require doing away with the many human fingerprints being observed in our climate today - less heat escaping to space, more heat returning to earth, shrinking daily cycle, shrinking yearly cycle, cooling upper atmosphere, etc.

Q: What do you think is the best argument climate change deniers make?

A: The one advantage that climate science denial has is all that needs to be done to delay action on climate change is to foster doubt and confusion. To achieve this, they don't have to provide an alternative, coherent position - they just have to cast doubt on the overwhelming body of evidence that humans are causing global warming. So there is no single, best argument against climate science - just an incoherent soup of noise that nevertheless is effective in confusing the public and delaying support for action to mitigate the worst impacts of climate change.

How to respond to science denial

Q: Tell us about the relationship between acceptance of the science and acceptance of policies to respond to the problem described by science... And what's the relationship generally between scientific and policy beliefs? Can one influence the other? Does the causality run both ways?

That's a great question. Psychological research has found a strong link between acceptance of science and acceptance of policies. In particular, the work of Ed Maibach at George Mason University has found that public perception of scientific agreement is a "gateway belief" that has a flow-on effect, influencing a range of climate beliefs and attitudes including acceptance of climate policies. Maibach found that informing people about the 97% scientific consensus has the effect of increasing people's support for climate policies. Maibach found that consensus messaging is even effective among political conservatives. This underscores the importance of communicating the scientific consensus and closing the consensus gap.

Q: ...I'd also like to know what your perspective is on the feasability of reversing climate change or bringing it to a halt? In other words, do your findings on the psychology behind climate skepticism provide any leads on how to remove this attitude from the population?

A: How to respond to climate science denial and turn this situation around? I'm doing a PhD on this very question and I believe the answer is inoculation - we need to inoculate the public against the misinformation that originates from science denial. We will delve into how to do this in week 6 of our course but I touch on this briefly in a recent Conversation article:

Q: You mention that you're looking into "inoculation against misinformation." What are some ways to encourage skepticism?

A: In my own research, I've found that explaining the techniques used to distort science is quite powerful in inoculating against misinformation - it completely neutralises misinformation. So that is the approach we take with our course - we debunk all the most common climate myths by explaining the techniques and fallacies used to distort the science.

Q: Don't you feel there's a danger in talking about the motivations of people who deny climate science, that discussion of motivations can be used to try to shame people into changing their beliefs rather than to persuade them with arguments?

A: Really incisive question, thanks! The challenge here is that the scientific evidence tells us that persuading people who are in denial with scientific arguments is futile or counter-productive. This finding underscores this important principle: scientists and science communicators need to take an evidence-based approach to science communication and that means heeding the scientific research into how people process evidence. And this social science research tells us that motivated reasoning has a strong influence on how people process evidence.

I think understanding motivated reasoning is also important because it helps people understand that people who use the techniques of denial aren't necessarily trying to intentionally deceive people. They can be genuinely held beliefs arising from cognitive biases. It's really important that people understand this - I explain it in my video lecture on the characteristics of denial:

Q: Is there any meaningful action I can take as an individual? Or, should I just start stashing guns, drugs, canned goods, and water filters in a nearby Appalachian cave?

A: Please don't hole up in a cave - we need you. There are two things an individual can do - walk the walk and talk the talk. Walk the walk means being more energy efficient and reduce your own individual footprint. Talk the talk means communicate the realities of climate change and the need for action to your friends, family and most importantly, your elected officials. When enough people speak up to politicians, the politicians will realise that the one thing they care about - their job - is at stake and will act accordingly.

Q: What if in the next few years Climate Change Deniers fizzle away (doubtful, I know)? ... What would you turn your research, your time, your attention to next?

A: Let's say hypothetically that we are successful in reducing the influence of climate science denial to the point where it has no significant effect on society. What next? Well, I must confess I have given this some thought and I would probably turn my attention to other forms of science denial. Evolution denial is something I'm quite interested in but a form of denial that is of more societal consequence is vaccination denial. Preventable diseases are making a comeback because of this form of science denial and it's completely unnecessary.

Q: How do you feel about Climate Change Denialists adopting the name "Skeptic"?

A: I think it is extremely unfortunate that the characteristics of science denial - cherry picking, conspiracy theories, logical fallacies - have come to be associated with the good name of skepticism. I've written an article on this very topic, published last week in Skeptical Inquirer:

These are just the tip of the iceberg - only part of my answers and a very small fraction of the total number of comments on the AMA page (currently there are 2,487 comments). If you have a few spare hours to kill, go check out the full AMA page on Reddit.

No, wait, if you have a few spare hours, enrol in the Making Sense of Climate Science Denial MOOC!

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Comments 1 to 23:

  1. "When enough people speak up to politicians, the politicians will realise that the one thing they care about - their job - is at stake and will act accordingly."

    Actually, the one thing that politicians care for are campaign funds to keep their jobs. That determines whether or not they get elected. These funds, of course, come from the fossil fuel industry which has the deepest pockets of all. There is no way we can match the money and power of the corporate elite.

    Also, if enough people complain to politicians about any one subject that they don't want to accept they will simply lie about their position in order to get elected.

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  2. @ villabolo   And that of course is why I am encouraged to see lawsuits being initiated in several countries against politicians who fail to act responsibly based on the science.  If they are successful, I believe (maybe just hope) that the lawsuits will trump the lies.

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  3. Under Scientific Consensus, the first questioner is confusing consensus as a decision making process with consensus amng scietists on what constitutes the body of accepted and agreed upon scientific evidence. The two are quite different uses of the word.

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  4. @ SkepticalinCanada #2,

    Are those lawsuits directed at individual politicians or their party?

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  5. Consensus starts with nomenclature so to say consensus is not a part of science is incorrect by-ahem- definition.

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  6. I think the most important thing about scientific consensus, is that it should be the guide to policy. Consensus may change (eg fat in diet) in which case policy needs to change with it, but the current scientific consensus, when strongly formed, is the only rationale guide to policy.

    For practising scientists, the consensus is usually the underpinning for further work, but of course a scientist should challenge the consensus when there is an observation that doesnt fit or an hypothesis that better fits observations. This is the normal progress of science. eg I would assume say Fourier's Law in my work pretty much without question. However, if some observation turned up that defied explanation within that framework and I could dream up an alternative that also worked with all previous observations, then I am in position to challenge that consensus.

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  7. I understand that the intended meaning of consensus is a 'majority view' on a matter. However, not all dictionaries include that definition for the term. My Oxford Dictionary 1985 edition does, but my Webster's dictionary published in 1988 does not. And our Scholastic Children's Dictionary published in 2002 defines consensus as "An agreement among all people in a discussion or meeting". So, by definition, there is no consensus regarding the meaning of the term consensus according to the definitions provided by Websters and Schoalstic.

    Neil Degrasse Tyson refers to generally accepted scientific understand as objective truth.

    I like that term, objective truth, because it reinforces the need to be objective and points out that all people who truly objectively review all of the evidence on a matter will come to essentially the same conclusion, the objective truth that could be altered by new information, but that is not altered until there is new substantive information that objectively warrants a change of the understood objective truth.

    However, the term Objective Truth is also used in a variety of ways including claims of objective truths about unobservable matters like spirituality, matters that are important to ponder but that cannot truly be evaluated 'objectively' at least not yet.

    What a conundrum. (at least everyone can agree about that term ... or can they?).

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  8. OPOF @7, my Shorter Oxford defines "consensus" as:

    "1.  Phys. General concord of the different organs of the body in effecting a given purpose. ...

    2. Agreement in opinion."

    The first recorded instance of the first meaning is in 1854, of the second, it is in 1861.  Most internet sources define "concensus" as "general agreement" which is not the same as unanimous agreement.  It is glossed as such by Miram Webster.  However, Miriam Webster provide a second defintion as "the judgment arrived at by most of those concerned" (my emphasis).  Based on that, I believe the idea that "consensus" means the same as "unanimous opinion" is just an error of interpretation.

    The error arises, I believe, due to many people being familiar with the term from consensus decision making, which often involves a requirement of unanimity, especially from small groups.  Even there, however, near unanimous decisions are often accepted as part of consensus decision making.  Indeed, for clarity it may be helpful to borrow some terminology from that field.  Specifically, some consensus processes can be decided by an agreement by all but one member or all but two members, described as U-1 and U-2 respectively.  With so large and amorphous a body as that of all climate scientists, using individual counts of dissenters is hardly usefull.  However, we might define a "strong consensus" as U-5%, ie, agreement by all but 5% or less of climate scientists, and a "weak consensus" as U-10%, ie, agreement by all but 10% or less of climate scientists.

    If we use those definitions, and by my estimate from familiarity with various surveys, there is a strong consensus that:

    1) Anthropogenic emissions are the primary (>80%) cause of the recent rise in CO2 concentrations;

    2) That increasing greenhouse gas concentrations cause an increase in Global Mean Surface Temperature; and

    3) That anthropogenic forcings have caused more than 50% of recent global warming (ie, warming since 1950).

    There is at least weak consensus that:

    1) That anthropogenic forcings have caused more than 50% of industrial era global warming (ie, warming since 1750);

    2)  That unmitigated global warming will result in temperature increases over the coming century between the upper bound of RCP 8.5 and the lower bound of RCP 6.0; and

    3) That unmitigated global warming has a statistically significant risk of being very dangerous.

    Finally, there is at least a super majority (66% or more) of the opinion that unmitigated global warming will more likely than not be very dangerous.

    Re Degrasse's statement, "objective truth", if it means anything more than just "truth" means merely the truth, objectively determined.  By definition, therefore, the consensus opinion of scientists is not thereby objective truth, for it is determined by a subjective measure, ie, the actual opinions of scientists.  It is, however, our current best guess as to the truth objectively determined, ie, as determined by the scientific method.

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  9. The lukewarner question is a good one and so is the answer. The lack of action by Government and companies needs only to look at reasons for delaying action. For a better future climate that is not possible

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  10. Tom Curtis,

    Truth can be understood to be "in agreement with facts". In that sense it does not relate to spirituality or religious beliefs which have no objective confrimable facts for consideration.

    It is probably better to describe the intended meaning of a term like consensus (or strong consensus - weak consensus, or objective truth) whenever such a term is used. English is an amazing evolving language. Regardless of the history of meaning of a word, an expected meaning of a term should not be relied upon.

    The full definition of consensus in the 1988 edition of "The New Lexicon - Webster's Encyclopdic Dictionary of the English Language" is:

    "concord (of opinion, evidence, authority, testimony, etc.) [L. = agreement].

    And concord is defined as "a state of agreement or harmony ll a treatment or agreement ll (mus.) a chord harmonious to iteslf, not needing others to resolve it ll (gram.) agreement between the forms of words, e.g. (for number) 'this house, these houses' [F. concorde]"

    By that definition the interpretions of the term to mean unanimous agreement are not currently 'an error of interpretation'. Believing or claiming it to be an error of interpretation is an error.

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  11. "what are the main reasons someone would deny climate change?"  Some of the people I mix with and who dont seem to mind assuming everyone shares their view seem to have a suite of beliefs that seem to tie together - homosexuality is a lifestyle choice, the university (name any one) is a hot-bed of Moaist and Trotskyites, New Scientist is a left-wing magazine and you dont believe all that rot about global warming do you? - Oh, and I hand our how to vote cards for (guess who).  This gives me the creeps as to what the hell is going on in one of our major political parties.

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  12. OPOF @10, dictionaries only, or should only, report on actual usage.  In this case, an example of actual usage is found in the wikipedia article to which I previously linked.  In particular, that article has a section heading "near-unanimous consensus".  If "consensus" means "unanimous agreement", then "near-unanimous consensus" is a contradiction in terms.  It should strike you as odd or as nonsensical as, for example, a dark light, or a spherical cube.  As it does not, or at least it does not strike me that way, current usage does not make unanimity a necessary feature of consensus.  Ergo, treating it as such is indeed an error, whether in 1860 or 2015.

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  13. villabolo @4, one of the current lawsuits has been filed against the Dutch government (as documented at The Guardian), while others I am aware of have been filed against individual politicians in the United States.

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  14. IMO, lawsuits against politicians or 'anybody' based on their 'beliefs' (or lack of action based on someone else's beliefs) is a very slippery slope.

    I'm for more education and interaction with people that aren't yet convinced of the seriousness of AGW. Lawsuits against polticians or whole countries/governments, will be seen more as radical publicity stunts by your average Joe and may not have the intended results on the public mind. After all, it is the people who will drive the politicians to drive change on this issue, IMO.

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    @14 jenna.  It doesn't look as though that lawsuit against the Dutch government has anything to do with "beliefs" it's focused on lack of action that 'We The Dutch People" believes needs to be taken.  

    (no I'm not Dutch, just a figure of speach)


    "Dutch government facing legal action over failure to reduce carbon emissions.  Landmark case brought by 886 Dutch citizens aims for more robust policy to cut emissions within targets set by IPCC to help avoid critical 2C rise in global temperatures.

    The first public hearings will take place in the Hague on Tuesday in the first case in the world to use existing human rights and tort law to hold a government responsible for failing to reduce carbon emissions fast enough. ...

    They will ask the judiciary to declare that the Dutch government must implement policies to reduce its emissions by between 25% and 40% below 1990 levels by 2020. This was the target for developed nations – established by the Intergovernmental Panel on Climate Change (IPCC) – as necessary to create a 50% chance of avoiding a dangerous 2C rise in global temperatures."

    Unfortunately the legal system moves slower than our cryosphere is melting.

    The Dutch government is facing the threat of legal action if it fails to take swift action on climate change.

    The move, which is thought to be the first time that European human rights legislation has been used to take a government to court over climate change failures, is intended to put the spotlight on what campaigners say is a lack of action and force them to prioritise cuts in greenhouse gas emissions.

    Urgenda, the pressure group behind the move, sent a letter to ministers calling on them to announce new initiatives on cutting emissions. Without that, the group said it would proceed to the courts.

    The government of the Netherlands has not yet responded.

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  16. PS

    The lawsuit has been brought by the sustainability foundation Urgenda with 886 Dutch citizens acting as co-plaintiffs including teachers, entrepreneurs, artists and children legally represented by their elders.

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  17. SkepticalinCanada @ 13,

    you wouldn't have a list of such US lawsuits would you?

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  18. Tom Curtis@12,

    I will try to clarify my recommendation.

    Do not presume an interpretation of a word like consensus when its interpretation is key to the message you are trying to convey. Try to explain what you mean whenever you use it.

    An additional recommendation is: Do try to tell people what they should have understood if you did not explain the intended meaning. Simply agree that there are multiple possible interpretations, but you meant what you clarify the intended meaning to be.

    The pursuit of things like convenience, expediency and brevity can lead to disasterous unintended and unnecessary consequences.

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  19. @17  Sorry, I do not have a list, but a search for something like "lawsuits against us politicians climate change" will bring up a few, including an insurance company class action suit against Chicago area municipal governments. I assume that, as the list grows, someone somewhere will keep track for us, especially as the list of successful lawsuits grows. 

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  20. OPOF @18, I certainly have no argument with your recommendations.

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  21. An interesting list of denialist tactics is on

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  22. An intriguing case study in denialism is climate scientist Cynthia Nevison complaining about global warming deniers, but vigorously promoting anti-vaccine crankerism and even being a leader in that "field."  Respectful Insolence has details.  I truly am intrigued by her case, from a psychological standpoint; John Cook, do you have any thoughts on how she maintains those two contradictory positions? 

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  23. "Scientific consensus" has a distinct meaning in science. It is not a debate, it is solely dependent upon the quantity and quality of evidence published in high level peer-reviewed journals. As I've written before, it is not a debate, it is not an argument. It is only one thing, it is collective agreement by the scientific experts on a particular scientific issue. It is absolutely based on evidence, and evidence alone. 

    Like "scientific theory", "scientific consensus" has been polluted by the the more common, and less scientific, definitions of these words. In science, a theory is essentially a fact, and a fact that can be predictive. The scientific consensus is not based on a debate amongst 10 scientists in a room. It is not some form of democratic voting. It is just a weighing of the quality and quantity of evidence.

    Scientific consensus is what eventually forms a scientific theory, which is predictive in power. Anthropogenic climate change has already achieved a consensus. 

    The scientific consensus is solid about anthropogenic climate change. If someone wants to refute that, they need to bring real scientific data in the volume and quality that supports the consensus, not logical fallacies or conspiracy theories.

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