The “Climate Sensitivity” folly

The Lewis & Curry paper of 2014, where they set out to estimate Earth’s climate sensitivity to “GHGs” apparently ‘based on observations’, neatly identifies the fundamental problem with the whole “climate sensitivity” issue:

It is not a scientific proposition. It starts out as a speculation, a mere conjecture, and ends with a circular argument based on that very conjecture.

The conjecture of course being:

“More CO2 in the atmosphere can, will and does cause a net warming of the global surface of the Earth.”

This is the basic premise behind the entire AGW industry. The one thing that HAS TO be correct in order for all the other claims made to even stand a chance of being taken seriously in a proper scientific context.

But has this basic premise ever, anywhere, by anyone, been verified empirically through consistent observations from the real Earth system?

Of course not! Not even remotely so!

It is still nothing but a loose conjecture …

And yet NO ONE seems to acknowledge even in the slightest how this might pose a problem. All you get if you bring it up are shrugs of indifference and/or tuts of disapproval. ‘Go away, we’re discussing real, important issues here!’

The irony …

It is all rather fascinating. EVERYONE appears to take for granted, without a single critical thought in their mind, that this fully unsubstantiated assertion is in fact rather a long-established Truth. Warmers and lukewarmers alike. It’s like a complete blind spot to all of them. It simply isn’t seen as an issue at all. People’s eyes glaze over whenever someone tries to call their attention to it. They simply don’t understand what you’re getting at. In their world, if theoretically it should be like that, then it is like that. To them, the Truth of inescapable net CO2 warming just is, like solid bedrock (you can feel it under your feet and so you know it’s real), a piece of self-evident fact that no one apparently sees any point in even addressing, much less testing, like “Do we question gravity?”.

The problem is, gravity’s effect on its surroundings is an empirically established fact, confirmed every day through billions upon billions of casual observations. The claimed warming effect of atmospheric CO2 on the mean surface temperature of the Earth, on the other hand, has NOT been empirically verified. At all. Not even once.

A claim that more CO2 in the atmosphere will and does make the global surface of the Earth warmer on average comes without ONE SINGLE SHRED OF ACTUAL EMPIRICAL EVIDENCE! *

And still people walk around taking it as gospel truth. In all sincerity equating its validity to gravity’s pull. Which, to be frank, utterly boggles my mind …!

Most people naturally don’t know that the basic premise of the AGW proposition comes without even a single piece of empirical evidence from the real Earth system. They simply assume it does. That there are tons of evidence out there. Because that’s what they’ve been told. By the people who should know this. The “experts”. And they’ve been told so for a long time, repeatedly, incessantly. Directly and indirectly. Never actually shown any such evidence, of course. (And they don’t ask for it either …) Only insistingly assured that it does exist. Somewhere. And piles of it.

* That CO2 is a gas that absorbs (and emits) radiation at certain wavelengths within the EM spectrum is an empirical fact. And no one claims otherwise. However, the notion that putting more of it into the atmosphere will therefore automatically (by physical necessity) induce a NET warming of the surface underneath, is NOT. It simply doesn’t follow. You cannot presuppose a direct connection here … You need to test it! Verify it empirically.

CO2 being able to absorb and emit radiation at ‘normal’ temperatures and pressures makes it a “radiatively active gas”, not per se a “greenhouse gas”, because the ‘greenhouse’ term naturally implies a net warming effect as a specific consequence of its radiative properties, which is something that isn’t empirically verified in the real Earth system. There are other mechanisms at work …

So how does Nic Lewis and Judith Curry arrive at their “observationally based climate sensitivity” figures?

By assuming that all ‘global warming’ between chosen segments along a temperature graph is caused by the rise in atmospheric CO2.

So what has actually been “observed” here?

Is the claimed global temperature rise (ΔT) from the last half of the 19th century to the beginning of the 21st an “observed” one?

No! It’s an altogether made up one. The makers of the global temperature records can claim it to be whatever they want it to be. And they do …

Is the claimed increase in ‘radiative forcing’ (ΔF) from the last half of the 19th century to the beginning of the 21st an “observed” one?

Of course not. It is a calculated one. A model result. Based on certain unverified assumptions. Like the “All Else Being Equal” meme.

Here are the equations used to estimate Earth’s “climate sensitivity” to the rise in “GHGs”, based on “observations” that aren’t really:

  • TCR (“transient climate response”) = F2 x CO2 (ΔT/ΔF)
  • ECS (“equilibrium climate sensitivity”) = F2 x CO2 (ΔT/ΔF – ΔQ)

where ΔQ represents the change in ocean heat uptake as the total ‘forcing’ changes, basically that part of the energy imbalance allegedly created by the ‘forcing’ which doesn’t show up immediately as an increase in surface temperature, but which is rather stored as ‘ocean heat’ (OHC); one is almost tempted to call it the “missing heat” or the “warming in the pipeline” factor.

Is the change in this variable, then, something that’s been “observed” since the latter half of the 19th century?

What do you think …?

Nope. It’s models once again.

Well, anyway. Let’s just try it.

According to Lewis & Curry, the standard central estimate of F2 x CO2 (the increase in ‘radiative forcing’ from a doubling of atmospheric CO2 concentration) is +3.71 W/m2.

So, what they came up with was the following: Using “HadCRUt4” as their global temperature guide, they found a rise in the mean level of global surface temperatures (ΔT) from their chosen “base period” (1859-1882) to their chosen “final period” (1995-2011) of 0.71 Kelvin. During this same stretch of time (of around 135 years), they then speculated (‘estimated’) a global mean increase in ‘radiative forcing’ (ΔF) from the rise in “GHG” concentration in the atmosphere amounting to 1.98 W/m2, and a simultaneous increase in the heat uptake rate of the global ocean (ΔQ) equal to 0.36 W/m2.

Entering these figures into the simple equations above will then provide us with “observationally constrained estimations” of TCR and ECS, like this:

TCR = 3.71 * (0.71 / 1.98) = 1.33K

ECS = 3.71 * (0.71 / 1.98 – 0.36) = 1.63K

Lewis & Curry’s ‘best estimate’ TCR exactly matches my +1.33K, while their ‘best estimate’ ECS somehow ends up as +1.64K.

Close enough, though …

So it’s really that simple. You take two segments of the global temperature anomaly curve. You note how much the temperature has apparently gone up in between them. You assume this rise is ALL due to a concurrent rise in “GHGs” in the atmosphere. You then use a radiative transfer model to compute, based on an ‘all-else-being-equal’ approach, the increase in ‘radiative forcing’ from this increase in “GHGs”. Finally you estimate how much more heat the global ocean has managed to swallow per unit time during the assumed increase in ‘forcing’, basically by putting your finger in the air. And voilà!

As you can see, it’s nothing but assumptions all the way down. No real empirical evidence from the actual Earth system to support any of it.

And yet – in this postmodern day and age – it passes peer review and is thus called “Science!” …

Go figure.

The Lewis & Curry 2014 results and implications were discussed (by the two authors themselves) here and here upon the paper’s original publication.

17 comments on “The “Climate Sensitivity” folly

  1. okulaer says:

    If you’re interested, you can follow a recent exchange between NASA GISS (and Columbia Univ.) “scientist/modeller” Dr. Jan P. Perlwitz and myself (“Kristian”), going perhaps (?) a bit more in depth on this very issue, starting here:

    • markstoval says:

      I read all that exchange today. All I can say is — unbelievable. The “good doctor” does not seem to know what science is, what the scientific method is, what logical argumentation is, what the null hypothesis is, or when he has totally lost a debate.

      One does wonder how these clowns get PhDs in the first place.

      Thanks for the pointer to that exchange. I’ll have to read more over at Spencer’s place in the future. 🙂

  2. markstoval says:


    This post may be one of the best I have read on this topic. You have simplified it done to the very obvious fact that it is all speculation and models. There is no proof of any NET warming due to CO2 at all.

    You write: “A claim that more CO2 in the atmosphere will and does make the global surface of the Earth warmer on average comes without ONE SINGLE SHRED OF ACTUAL EMPIRICAL EVIDENCE! ” That is a point that I wish we could hammer into the lukewarmer’s head. But even the lukewarmers claim that CO2 warms the surface and there must be TONS of empirical evidence out there to show that. (but they never give me any)

    I think that this post is a great starting point to show a few science teachers I know. Perhaps it will help them see the light. Thanks for the post

    ~ Mark

  3. markstoval says:


    I mentioned this post and that exchange with Dr. Perlwitz over at wuwt. I got back this reply to my comment:

    January 11, 2016 at 5:02 pm

    I have read most of the link you suggested, the discussion between Kristian and Perlwitz. Absolutely astonishing that Perlwitz could not or would not give something in the way of an answer. He is a real twit and sounds very childish. And this is someone from NASA, GISS and Columbia? He is very obviously, completely
    without any sort of answer to the questions posed to him and given the credentials he supposedly has, should be more than happy to share his scientific knowledge concerning the subject of the discussion. After all, he, I assume, is paid by our taxes… So why play babyish word games like he does? The answer is obvious…He doesn’t know. He can’t explain how C02 would cause global warming because he has no idea.

    The discussion between Perlwitz and Kristian should be published far and wide and even sent to some of our reps in Congress and the Senate. I am appalled.

    Thanks again for the link.


    I tend to agree with “D”. I think that perhaps you should do a post on that exchange between you and the good doctor. Let your words and his words tell the story. Such a post would be a good one to link to when discussing what is so very wrong with the ‘consensus’ of the CO2 cult.

    Disclaimer: I have posted one measly time in the last 6 months or so, so I fully understand that you might not have time for such an endeavor. I know better than most that time is a limited resource. But if you do find the time, I think it would be a great post.

    PS: Do you comment over at Spencer’s place often?

    • okulaer says:

      Hi, Mark.

      I did think about just that, posting the exchange, but in the end I decided against it, rather preferring the link. I don’t think much would come of it even if I did do a separate post on it; such people are not interested in proper interaction on these issues anyway, they simply don’t care. Their (political) message is way too important to them. To them we’re only a nuisance they are sometimes forced to deal with, and when they do, they spend all their time and effort at finding ways to dismiss offhand rather than actually address our arguments. Because they don’t understand them and they don’t want to understand (you know, the whole thing about not letting facts get in the way of a good narrative). Only yesterday I read a comment (by a commenter named “Ted”) on one of Goddard’s threads summarising quite succinctly the mindset of these people (it could very well have been about Perlwitz, although it wasn’t):
      “The only real problem he has is the blind arrogance that a man shows when he’s trying to convince himself that he’s right. I, too, had hoped I could talk him through that, at least enough for him to help me understand how he arrived at his beliefs. In a way, he did. He convinced me that his beliefs are the product of psychology, rather than climatology. I think he’s tried looking at the evidence, and he couldn’t understand it. He knows he’s intelligent, because he agrees with the experts. So the research must be beyond the comprehension of anyone but those same experts who wrote the papers. Because we disagree with those experts, we must be far less intelligent than Martin, and therefore utterly incapable of understanding ANYTHING on the level he does. Hence the baseless confidence, and unshakable arrogance. He knows we can’t possibly be right, because we’re not intelligent enough to agree with the experts. And he knows the experts are right, because he’s not intelligent enough to understand them. And he probably doesn’t even see the problem with that circle of logic.”

  4. jinghis says:

    I think this statement by Jan was correct, “Radiative forcing by a climate driver is defined for the top of the atmosphere (TOA), or at the tropopause, not at the surface.”

    That means that surface temps are meaningless and basing TOA radiation rates on surface temperatures is “puzzling”.

    They must think we are stupid. . .

  5. I notice that you have not one physical equation for radiative transfer in this post. Consider what happens when a photon enters the atmosphere.

    You can find them in any thermodynamics textbook or straight from wikipaedia:

    The equation of radiative transfer simply says that as a beam of radiation travels, it loses energy to absorption, gains energy by emission, and redistributes energy by scattering. The differential form of the equation for radiative transfer is:
    \frac{1}{c}\frac{\partial}{\partial t}I_\nu + \hat{\Omega} \cdot \nabla I_\nu + (k_{\nu, s}+k_{\nu, a}) I_\nu = j_\nu + \frac{1}{4\pi}k_{\nu, s} \int_\Omega I_\nu d\Omega
    where j_\nu is the emission coefficient, k_{\nu, s} is the scattering opacity, and k_{\nu, a} is the absorption opacity.

    Now – to disprove the effect of GHGs you need to show this is wrong.

    And of course your whole premise that it has never been empirically observed is also wrong. It has been demostrated many times in laboratories around the world – even by middle school students. I notice you put weasel words like ‘Earth system’ into your claim though, because you thought this was a cheap way of semantically winning the point, but you fail there also: First Direct Observation of Carbon Dioxide’s Increasing Greenhouse Effect at the Earth’s Surface

    Now, scientists have known about the GHG effect for over 200 years. The temperature of the planet would be much, much colder otherwise. They figured this out long before calculators or computers or computer models. Those that deny the GHG effect are simply wrong. Ignorant, stupid, insane or just plain evil. Those are the four possible reasons why they’re wrong. Which of these slippers are you wearing?

    • okulaer says:

      Those that deny the GHG effect are simply wrong. Ignorant, stupid, insane or just plain evil. Those are the four possible reasons why they’re wrong. Which of these slippers are you wearing?

      What is this!?

  6. okulaer asks: “What is this?”

    It’s an ad hoc ‘theory of wrongness’ — why do people propose/believe wrong answers? If we ignore trivial categories (e.g., misremembering a fact) then there are rally only four candidate answers. It can be ignorance. It can be stupidity. It can be Insanity. Or it can be through sheer malice (i.e., lying).

    As I’ve written elsewhere:

    I consider the run-of-the-mill commenter at WUWT to just be ignorant. No, great sin in that – we’re all ignorant on different subjects. Of course more than a few simply can’t understand the basics even when they’re spoon-fed the answers. You can’t fix stupid.

    And of course there are the requisite number of conspiracy theorists – global warming is just a big fraud promoted by a cabal of well-paid climate scientists. Yes, and the moon landing was staged on a Hollywood backlot.

    Now, if your local denier/pseudosceptic doesn’t fall into one of the above categories we have but one left: just plain evil. Evil knows. They know the snake oil they’re peddling and do it with eyes wide open.”

    Now, you have written that the GHG effect is not real. It is real. It’s a fact. Therefor you’re just wrong. Now the real questioning begins – why are you wrong? Which one of the 4 categories do you fall into? It could be you’re ignorant of the basic physics. It could be that despite being spoon-fed the correct physical equations you simply aren’t capable of understanding them and working through the math yourself. It could be that despite the ability to work through the equations and arrive at the same answers as everyone else you *still* refuse to accept reality. Or it could be that you know the correct answer, but prefer to spread the wrong answer.

    It’s really pretty simple. So I’ll ask again: Which of the four slippers are you wearing?

  7. If you’re not wrong, then show where the radiative transfer equations are incorrect. The radiative transfer equations require that the theory of GHGs be true; just as the theory of gravity requires that objects fall at a prescribed rate of acceleration.

    This should be very simple to do – i.e., the actual paper to show the equations incorrect shouldn’t require more than two or three pages. Your new theory will overturn all of planetary physics, since the same equations apply to all atmospheres. A Nobel prize will shortly follow as 200 plus years of science gets overturned.

    The alternative is that you are insane — i.e., you believe you are right in some extreme case of the Dunning-Kruger effect while all the physicists in the world who have studied the subject are wrong.

    Since I do not believe you will every write said paper and that a Nobel Prize is not in your future, I must then vote for insane.

    • okulaer says:

      If you’re not wrong, then show where the radiative transfer equations are incorrect.

      They’re not incorrect. No one on this blog ever claimed they’re incorrect.

      The radiative transfer equations require that the theory of GHGs be true (…)

      Er, no.

  8. Kevin O'Neill says:

    Once again, I suggest you read a textbook or just go start with Wiki — Radiative Forcing.

    “For a greenhouse gas, such as carbon dioxide, radiative transfer codes that examine each spectral line for atmospheric conditions can be used to calculate the change ΔF as a function of changing concentration. These calculations can often be simplified into an algebraic formulation that is specific to that gas.

    For instance, the simplified first-order approximation expression for carbon dioxide is: ……

    I’ll await your paper telling us why these radiative transfer codes are incorrect. LOL

  9. okulaer – if neither radiative transfer models nor radiative forcing equations are wrong, then GHGs directly cause warming. Radiative transfer leads directly to radiative forcing.

    It’s a simple exercise to determine what the temperature of the earth *should* be without GHGs. It’s also a simple exercise to compare that calculation to reality. Reality is much warmer. It is not coincidence that the difference is the sum of the forcing effects of GHGs.

    Your notion that this effect has never been observed empirically is also wrong – as I also pointed out. We have measurements that show the spectral emissions of the planet and they completely agree with theory. Eli Rabett has explained this numerous times over the years.

    We also have the surface observations that I cited above.

    Those that do not believe in the GHG effect are either ignorant, stupid, insane, or just plain evil.

    • okulaer says:

      okulaer – if neither radiative transfer models nor radiative forcing equations are wrong, then GHGs directly cause warming.

      Nope. Not in the earth system.

      And with that, I think this mightily productive discussion has reached its natural end …

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