Consensus in Climate Change Science

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This is an excellent video put together by consensus in science expert John Cook. John is the author of the excellent must-read book Cranky Uncle vs. Climate Change: How to Understand and Respond to Climate Science Deniers.

I have always been interested in the concept of consensus, even before that word became centered in the pro vs. anti science debate. In Anthropology, we have huge problems with consensus. In at least one branch of Anthropology, consensus can never be achieved because all good work is defined as breaking consensus. The moment you get close to consensus, you’ve failed. (That’s socio-cultural anthropology, modern style). In another branch of Anthropology, we deal with questions that can’t really be answered at that level, but sort of can be. So there is never consensus in the sense that of the many possible explanations for a thing, there will always be a list of possible, and often very distinctly different, alternative explanations. But, over time, the list changes. One hopes for the list we have now being better than the list we had a decade ago, even if both lists are approximately the same length. (Example: Reasons for the origin of bipedality in the human lineage.)

There is a particular kind of consensus that to my knowledge my friend John Cook does not talk about (yet, he’s got most of this covered very well): Beer pitcher consensus. It goes like this. Suppose there is a range of thought on a particular narrowly defined scientific question. Since this is about climate, let’s do a climate one. The question might be: What is the best value for “climate sensitivity.” This is the number of degrees Celsius that the atmosphere at the Earth’s surface will go up with a doubling of atmospheric CO2 from pre-industrial values (say that was about 280ppm). (I’m oversimplifying the concept and the question slightly and I believe forgivably.) The answers range from a somewhat pedantic and absurd 2.0 to an alarming and probably alarmist 5.6 or so.

Now, get a bunch of experts on this question, say at a conference. Sit them down for a beer. After a couple of beers, tell them, “OK, folks, I’m giving each of you a piece of paper and a pencil. Write down a guess on the climate sensitivity value. Here’s the thing. Don’t show each other what you wrote down, only show it to me. And, if they are all the same value, I’ll buy pitchers of beer for the rest of your time at this conference, starting now.”

Had I simply asked this group of experts to tell me the climate sensitivity value, it would start a conversation that would go on for hours, and there would not be a single number. But if I do it as described here, they would all write down one number, and it would be 3.5 (I’m pretty sure).

That is the beer pitcher consensus.

Anyway, have a look at John Cook’s excellent video. It shows why most of the time you as a science oriented concerned lay citizen usually get this wrong, but in a harmless way. There is not a “97%” consensus. There is a full consensus; the number 97% is kinds of silly, and it is only part of the picture. The idea that global warming is happening and is human caused is, simply put, established scientific fact. There is no valid dissent. But, the number “97%” does have an important meaning and history in the debate. More to the point, not only is there a consensus on climate change and the human cause of it, but there is a consensus on the fact that there is a consensus!

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39 thoughts on “Consensus in Climate Change Science

  1. Great video, as always, by John Cook. The large scientific consensus is a thorn in the side of climate science deniers and they expend immense efforts to debunk it. They lost the scientific debate decades ago but, unfortuneately, they persist, driven by a warped obsession to a bankrupt political system and profit.

  2. Yes, very good, but the deniers won’t be swayed: they’ve done a good job smearing Cook, among others, so it will be very easy for them to give fake reasons to cast this as a desperate attempt.

    “They lost the scientific debate decades ago ”

    True, but to a believer having all the evidence against them won’t sway someone who believes they are right. It doesn’t even have to be in an area like this: we still get the occasional math crank who submits a “proof” that pi is rational, or that Cantor’s diagonal argument is flawed. If you’re a crank, and you believe in your pet topic, evidence against you isn’t evidence, it’s conspiracy (I’m not sure goal a conspiracy that says pi is irrational might serve, but…).

    So yes, the right has lost every scientific debate, and they recognized that long ago, which led to their decades long attack on science and “elites” who claim expertise in any discipline. The result is people like the two resident science deniers who couldn’t pass a college algebra class if they had to take one but both know the science and data analysis of climate science is wrong.

    Facts cannot overcome their intentional dismissal by folks dedicated to dishonesty, as the deniers are.

    1. dean says “The result is people like the two resident science deniers who couldn’t pass a college algebra class if they had to take one but both know the science and data analysis of climate science is wrong.”

      I would like to push back on this. My opinion on ECS (which is about 1.8C) is within the IPCC range of 1.5C to 4.5C. So how am I saying the science and data analysis of climate science is wrong? I am in the range of the scientific consensus. I don’t think my opinion of ECS is saying that the science of climate change is wrong. I am just saying I believe it will turn out to be at the low end of the range science suggests.

      So I do not consider myself a science denier. Perhaps if I advocated that the Earth had not warmed, that would be a fair attack. But I fully agree that the Earth has warmed and that some part of it is caused by humans. I just dispute how much of the warming has been caused by humans, and therefore believe ECS is on the low end of the consensus range. You might as well call all the authors and contributors of the five IPCC reports science deniers, because they set the range within which they believed ECS would fall (1.5C to 4.5C).

    2. So I do not consider myself a science denier.

      But you are and we all know it so perhaps we could just end the charade. It got boring several years ago.

      As Lionel points out, you are outside the consensus and have been for some time now.

      The beer pitcher consensus is >3K.

      Yet you deny that as well.

      So you are a denier and dishonest with it.

      Why not have the courage to own your political bullshit? I’m not saying we’d respect you for it but at least you’d be being honest for a change.

    3. BBD:

      I deny that I am outside the consensus. I simply do not agree with you. We will have to agree to disagree.

    4. > couldn’t pass a college algebra class if they had to take one but both know the science and data analysis of climate science is wrong.

      Before you tried the same thing and said I was wrong about some basic stats regarding bell curves, then when called on it, you pretended you were saying something else.

      You were also unable to recognize upside down data usage even when shown the code and a detailed explanation.

      My conclusion is you are mathematically incompetent but claim this is the case for others.
      Alternative is that you are competent but lie for partisan reasons and accuse others of being wrong.

  3. RickA keeps digging as the science has marched on.

    My opinion on ECS (which is about 1.8C) is within the IPCC range of 1.5C to 4.5C.

    Which estimate has now been revised in the scientific community:

    …bringing together evidence from observed warming, Earth’s distant past and climate models, as well as advances in our scientific understanding of the climate, our findings suggest that the range of ECS is likely to be between 2.6C and 4.1C.

    Guest post: Why low-end ‘climate sensitivity’ can now be ruled out

    Further discussion, on the paper behind the above cited Carbon Brief post is here:

    Note the discussion differentiating between the use of Effective Climate Sensitivity, the focus of this paper, and Equilibrium Climate Sensitivity (cue acronym confusion).

    Climate Sensitivity: A new assessment

    Note external links shown as emphasised in this quote:

    There is a new review paper on climate sensitivity published today (Sherwood et al., 2020 (preprint) that is the most thorough and coherent picture of what we can infer about the sensitivity of climate to increasing CO2. The paper is exhaustive (and exhausting – coming in at 166 preprint pages!) and concludes that equilibrium climate sensitivity is likely between 2.3 and 4.5 K, and very likely to be between 2.0 and 5.7 K.

    For those looking for some context on climate sensitivity – what it is, how can we constrain it from observations, and what observations are available, browse our previous discussions on the topic: On Sensitivity, Sensitive but Unclassified Part 1 + Part 2, A bit more sensitive, and Reflections on Ringberg among others. In this post, I’ll focus on what is new about this review.

    1. We will see if this paper holds up. I wonder if Nic Lewis will take a look at it and how many errors he will find? It sure doesn’t square up with the observationally constrained studies of ECS. So put me down as skeptical that this paper’s higher estimate will hold up.

      Oh well – time will tell whether ECS is 3C, greater than 3C, less than 3C or even less than 2C.

    2. Oh well – time will tell whether ECS is 3C, greater than 3C, less than 3C or even less than 2C.

      Time has told. Palaeoclimate behaviour is essentially incompatible with an ECS below ~2.5K and ‘works’ best with a value around or perhaps just above 3K.

      That’s why NL’s got such a flea up his arse about palaeoclimate sensitivity estimates 🙂

  4. RickA, your dispute of the anthropogenic contribution to the recent warming is null and void because it is highly contaminated by your right wing, anti-environmental, nature-is-expendable perspective. I should also add that your grade-school science education also heavily weighs against your meaningless opinion. The human contribution to the recent warming is 100% or close to it. The vast majority of statured scientists agree, and the empirical evidence virtually proves it. Get over it. Since you are also unwilling or more likely unable to counter a thing I have repeatedly said about Trump and the Republican Party’s concerted effort to destroy the environment for the benefit of short-term corporate profit, your presence in any discussion is something of a farce. Any ‘lurkers’ that you refer to reading this need to know that you stink at debating – essentially because you are always wrong.

    What is worse is that it has now been shown that humans have added more CO2 to the atmosphere since 1990 – the year of the first IPCC meeting – than in all of human history before then. This is solely down to a vile and persistent political and propaganda campaign waged by the fossil fuel lobby to distort the science and manipulate public opinion. Given that the oceanic uptake of heat leaves something like a 3 decade lag on surface temperatures, it is likely that we are committed to anthropogenic warming for another 3 decades or longer no matter what actions we take now. There is not a hope in hell of keeping temperatures under 2 degrees C. Given the ongoing procrastination, we are locked into 3 degrees or more. The outlook is dire whichever way one looks at it.

    1. The additional CO2 since 1990 is more due to opposition to nuclear power than anything else (in my opinion). People cannot oppose both global warming and nuclear power – since the solution to global warming is nuclear power. People who oppose nuclear power don’t really take global warming seriously, in my opinion.

      But we will see what ECS turns out to be. We should be in a much better position to determine that once we hit 560 ppm of CO2 in the atmosphere. So I am looking forward to that point in history and all the science which I assume will be done measuring the global temperature in that year, and therefore the instantaneous temperature difference between when we were at 280 ppm and the doubling point of 560 ppm and what that will allow us to estimate ECS to be.

    2. The additional CO2 since 1990 is more due to opposition to nuclear power than anything else (in my opinion).

      LOL. Got any energy economics cites for that?

      Thought not.

      Stop bullshitting.

    3. BBD:

      The more energy generated with nuclear, the less that needs to be generated with fossil fuels. Surely you don’t dispute this piece of common sense? If the world switched over to generating 80% of the energy with nuclear and 20% with renewable, we would avoid quite a bit of CO2 emissions – don’t you agree?

    4. Count me in with skeptics on the claim that lack of nuclear power is responsible for high CO2 emissions. I don’t think the numbers add up in any realistic nuke construction plan, even with full support.
      The increase in energy demand was too high. The largest increase in emitters China and India also had robust expansion of nuclear power in that time.

    5. The more energy generated with nuclear, the less that needs to be generated with fossil fuels. Surely you don’t dispute this piece of common sense?

      Not at all.

      If the world switched over to generating 80% of the energy with nuclear and 20% with renewable, we would avoid quite a bit of CO2 emissions – don’t you agree?

      Non sequitur. The 80% figure is unachievable in the necessary timescale. I can’t be bothered to quote the WNA at you yet again since you go into denial whenever shown evidence that invalidates your fantasies, but fantasies they are.

      And denialism it is.

  5. “The additional CO2 since 1990 is more due to opposition to nuclear power than anything else (in my opinion)”

    Typical covering up a patently unsupportable claim with the bullshit “opinion” stuff. The honest ending to that would be

    “The additional CO2 since 1990 is more due to opposition to nuclear power than anything else ( in the opinion I just pulled out of my ass since I have no evidence to contradict the science)

    “People cannot oppose both global warming and nuclear power – since the solution to global warming is nuclear power.”

    Amazing how you can post so many unsupportable assertions and still expect to be taken seriously. It’s no wonder you had to leave your (alleged) career as an engineer.

  6. MikeN says ‘count me in with skeptics [he means deniers]…’

    Given your complete lack of any relevant scientific knowledge, your opinion, as usual, is worthless. This has nothing to do with opposition to nuclear power. It has everything to do with immensely wealthy, powerful fossil fuel industries investing billions to distort science, push anti-environmental propaganda, and control government policy by co-opting politicians by effectively ‘buying’ them. This is part of the reason the US is a plutocracy.

    1. Actually, when mikeN said

      Count me in with skeptics on the claim that lack of nuclear power is responsible for high CO2 emissions

      I think his direct reference was that he doubted lack of nuclear power was responsible for the high CO2 values, nothing other than that in this one case.

    2. There’s no disputing it. You two are deniers. JeffH said so.

      Okay, that will be the last time I bother to speak up for you.

  7. This nuclear nonsense is a complete cop-out by right wing climate science deniers like RickA as a means of blaming progressives and environmentalists for our failure to deal with greenhouse gas emissions. These scoundrels will resort to any wretched tactics to avoid apportioning blame where it belongs: to the fossil fuel industries and the think tanks and PR firms they paid handsomely to distort the science and mislead public opinion. The powerful, immensely wealthy fossil fuel multinationals have had decades to develop technologies towards renewable energy, but they refused to act because short-term profit maximization was their sole agenda.

    I will be fair to MikeN and admit that I misread his post. After his stupid ‘carbon dioxide is not pollution’ post and many others I am conditioned to believe he will say something that is wrong. I stand corrected.

    1. I have admitted when I was wrong. I am surprised you don’t remember. Or maybe not – I am not wrong very often.

      I am off to the cabin for Labor Day, so have a great weekend everybody.

  8. “You should try it sometime.”

    I expect to see my great-niece’s pot belly pig flying itself to my house for treats and a back rub, then flying home, before I see rickA demonstrate anything resembling integrity.

  9. I have admitted when I was wrong. I am surprised you don’t remember. Or maybe not – I am not wrong very often.

    The pig flying comment is safe — more lies from the disgraced engineer.

  10. Words fail me too BBD as arch denier and clown-shoe ignoramus Abbott is appointed as UK trade envoy. Ability and knowledge not required for a UK Johnson government post—the boss cannot be shown up by his appointees, the fact that he shows himself up every time he opens his mouth is neither here nor there.

    Most recently, he railed against Covid “health dictatorships”, saying it was “a bad time for people that would rather not be dictated to by officials, however well meaning”.

    Source

    1. Oh god, Bojo’s actually done it.

      I had hoped he’d see the torches and pitchforks massing outside the window and do one of his by-now well polished U-turns.

      Fuck.

      This is just unreal.

    1. I thought the quote about COVID was from Boris and wasn’t sure which was ‘it’.
      I didn’t realize it was Tony Abbott. Weird you would have an Australian advising you.

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