The Keystone Issue of Global Warming

It is silly to argue whether CO2 in the atmosphere can cause global warming: It clearly does.  The issue is not "if" but "how much".  The warming from man’s CO2 might be 8 degrees in a century, as Al Gore might argue, in which case man’s CO2 would be incredibly disruptive.  Or it might cause just a few tenths of a degree of warming, which might be unnoticeable within the noise of natural climate variation.

Interestingly, the key to understanding this issue of the amount of warming does not actually lie in greenhouse gas theory.  Most scientists, skeptics and alarmists alike, peg the warming directly from CO2 at between 0.3 and 1.0 degrees Celsius for a doubling in CO2 levels  (this notion of how much temperatures would increase for a doubling of CO2 levels is called climate sensitivity).  If this greenhouse gas warming was the only phenomenon at work, we would expect man-made warming over the next century even using the most dire assumptions to be less than 1C, or about the same amount we have seen (non-catastrophically) over the last century.  Warming forecasts of this magnitude would not in any way, shape, or form justify the draconian economic impacts of many current government carbon reduction proposals.

The key, as I have written before (and here), lies not in greenhouse gas theory itself but in the theory that the earth’s climate is dominated by positive feedback.  This theory hypothesizes that small changes in temperature from greenhouse gas increases would be multiplied 3,4,5 times or more by positive feedback effects, from changes in atmospheric water vapor to changing surface albedo.

Let me emphasize again:  The catastrophe results not from greenhouse gas theory, but from the theory of extreme climactic positive feedback.  In a large sense, all the debate in the media is about the wrong thing!  When was the last time you saw the words "positive feedback" in a media article about climate?

Christopher Monckton has an absolutely dead-on post at Roger Pielke’s blog about this feedback theory that I want to excerpt in depth.

This chart is a good place to start.  It shows the changes in the IPCC’s estimate for climate sensitivity to CO2 and how it has changed over the course of the reports.  More importantly, he splits the forecast between the amount due directly to Co2, and the amount due to the multiplicative effect of positive feedback.  The green bar is the direct contribution of Co2, and the pink is the feedback.


We can observe a couple of things.  First, the IPCC’s estimate of the amount of warming due to CO2 directly via the greenhouse gas effect has actually been going down over time.  (Note that there are those, like Richard Lindzen, who suggest these numbers are still three times too high given that we have not observed a difference in surface and lower troposphere warming that greenhouse gas theory seems to predict).

Second, you will see that the IPCC’s overall forecasts of climate sensitivity have been going up only because their estimates of positive feedback effects have gone way up.  The IPCC assumes that feedback effects multiply warming from CO2 by three.  And note that the IPCC’s forecasts of feedback effects trail those of folks like James Hansen and Al Gore. 

So how confident are we in these feedback effects?  Well, it turns out we are not even sure of the sign!  As Monckton writes:

The feedback factor f accounts for at least two-thirds of all radiative forcing in IPCC (2007); yet it is not expressly quantified, and no “Level Of Scientific Understanding” is assigned either to f or to the two variables b and κ upon which it is dependent….

Indeed, in IPCC (2007) the stated values for the feedbacks that account for more than two-thirds of humankind’s imagined effect on global temperatures are taken from a single paper. The value of the coefficient z in the CO2 forcing equation likewise depends on only one paper. The implicit value of the crucial parameter κ depends upon only two papers, one of which had been written by a lead author of the chapter in question, and neither of which provides any theoretical or empirical justification for the IPCC’s chosen value. The notion that the IPCC has drawn on thousands of published, peer-reviewed papers to support its central estimates for the variables from which climate sensitivity is calculated is not supported by the evidence.

Given the importance of feedback to their forecasts, the treatment in the latest IPCC report of feedback borders on the criminal.  I have read the relevant sections and it is nearly impossible to find any kind of discussion of these issues.  A cynical mind might describe the thousands of pages of the IPCC report as the magician grabbing your attention with his left hand to hide what is in his right hand.  And what is being hidden is that … there is nothing there!  Feedback is the pivotal point on which the whole discussion of drastic carbon abatement should turn and there is nothing there. 

Monckton goes further, to point out that hidden in the IPCC numbers lies an absurdity:

if the upper estimates of each of the climate-relevant feedbacks listed in IPCC (2007) are summed, an instability arises. The maxima are –

Water vapor 1.98, lapse rate -0.58, surface albedo 0.34, cloud albedo 1.07, CO2 0.57, total 3.38 W m-2 K-1.

The equation f = (1 – bκ)-1 becomes unstable as b → κ-1 = 3.2 W m-2 K-1. Yet, if each of the individual feedbacks imagined by the IPCC is increased to less than the IPCC’s maximum, an instability or “runaway greenhouse effect” is reached.

Yet it is reliably inferred from palaeoclimatological data that no “runaway greenhouse effect” has occurred in the half billion years since the Cambrian era, when atmospheric CO2 concentration peaked at almost 20 times today’s value

Positive feedback can be weird and unstable.  If there is enough of it, processes tend to run away (e.g. nuclear fission), which is what Monckton is arguing that some of the IPCC assumptions lead to.  Even when feedback is less positive, it still can cause processes to fluctuate wildly.  In fact, it is fairly unusual for long-term stable processes like climate to be dominated by positive feedback.  Most scientists, when then meet a new process, would probably assume negative feedback until proven otherwise.  This is a particular issue in climate, where folks like Michael Mann have gone out of their way to argue that the world temperature history over the last 1000 years before man began burning fossil fuels is incredibly stable and unchanging.  If so, how can this be consistent with strong positive feedback?

Anyway, there is a lot more numerical detail in Monckton’s post if you want to dig into the equations.

I would add one thing to his analysis:  If you look at the last 100 years of history, the change in temperature given the observed change in CO2 levels comes no where close to a climate sensitivity of 3 or more, even when you assign all historical warming to CO2 rather than other effects like the sun.  In fact, as I showed in this analysis, climate sensitivity appears to be 1.2 when one assigns all past warming to CO2, and something well less than that if one accepts the sun and other effects also play a role.  These historical analyses would point to feedback that is either zero or negative rather than positive, more in line with what one would expect from complex natural systems.

You can see a discussion of many of these topics in the video below:

20 thoughts on “The Keystone Issue of Global Warming”

  1. Even when feedback is less positive, it still can cause processes to fluctuate wildly – yes, like one moment it might be an ice age, and then in a geological blink of an eye it’s not an ice age any more. Then a short while later it’s back into an ice age. Clearly, no such wild fluctuations ever happen in the Earth’s climate system and therefore there’s no positive feedback!

  2. Regarding ice ages, I found an interesting note here that mentions the changes in insolation as a result of Milankovitch cycles on the Arctic circle. The graphs in Figs 1 and 2 show a variation on the order of 100 W/m^2. That’s very large, and easily explains the size of the ice ages without having to assume massive positive feedback.

    Since the temperature between glacials and interglacials varies about 10 K, you could calculate a rough sensitivity of 0.1 K/(W/m^2). It’s not comparing like with like, though, since the global average insolation is not the same as the Arctic circle insolation. Ice ages are reckoned to be caused by changes in the Earth’s tilt which change the distribution of heat rather than the total amount. Less pronounced seasons give colder poles leading to spreading of the ice sheet and increased albedo. However, it is quite clear that the effect is a massive perturbation.

    So let’s see, the original post makes a number of points:
    Most of the predicted effect is due to a theorised feedback;
    The evidence quantifying this feedback is poorly documented and remarkably weak;
    It’s rarely discussed in any depth in popular presnetations;
    The estimates have changed significantly in only a few years, with the effect of CO2 on its own going down;
    The estimates are very close to being unstable, even though past CO2 levels ten times higher have not led to a runaway effect.

    How many of these have been answered? None.

    Instead, we get the ice ages presented as evidence of wild instability and hence large positive feedback. Which does not logically follow, unless you assume that the change in input corresponding to that output was appropriately small. Which even a moderate amount of Googling suggests probably isn’t true, and which the inexplicable failure to mention, let alone provide evidence for, renders the argument fallacious.

    So do we have any actual reason to think that the feedback parameter is this large, and what is the observational evidence for it?

  3. Scientist, looking at every paleo-climactic record I could find on the Internet, it seems that historical temperatures are quite well bounded, with regular patterns of oscillation between high and low values. I was not aware that bounded oscillation was the hallmark of positive feedback, but perhaps you are more knowledgeable in this subject than myself. In differential equations, bounded and or damped oscillation is a basic result of negative feedback, see the classic predator/prey equation.

  4. Have any of you guys hear what the New Jersey Nets are doing to in the fight against global warming? Not only are there games now cabon-neutral, but they traded Jason Kidd to the Dallas Maveriks for the a “better enviroment” also. Julianne Waldron explained to the media that Kidd was giving off to much Carbon dioxcide. “Jason Kidd always hustles when he is on the basketball court, and we all admire that greatly. But all of that running up and down the court, pushing the team out on fastbreaks, expending extra energy just to make a few extra points and possibly win a game, caused all of the players to breathe a great deal more heavily and thereby expel extra amounts of carbon dioxide into the air, and we all know that is bad for the environment. We made the difficult decision to trade Kidd in order to save the planet.” Check out this article I found on it “Environmental Activism is the Key to the Current Success of the New Jersey Nets

  5. Stevo – it only takes a few minutes of googling to find something that looks like it supports your dogma, but it would only have taken a few minutes more to read it.

       The Milankovitch hypothesis as formulated here does not explain the large rapid deglaciations that occurred at the end of some of the ice age cycles

    You could calculate a climate sensitivity of 0.1, but you’d be way off the mark. If you google a bit more on the author of the paper you cite, Gerard Roe, you might find his paper with Marcia Baker on climate sensitivity. the uncertainty in the climate sensitivity in 2 x CO2 studies is a direct and general result of the fact that the sum of the underlying climate feedbacks is substantially positive

    joshv – if you look at the past five million years of climate, the pattern is of long term cooling, with oscillations superimposed. Further back, the situation is not as you describe. See this image. The predator-prey equation that you mention of course also includes positive feedback – more of either species = more breeding = more of that species.

  6. I didn’t make any claims about whose dogma it supported, only that it indicated a change of 100 W/m^2 in Arctic insolation, which I suggest is a large enough change in input to be able explain a large change in output. Yes, the match is not perfect, and there are evidently other effects in place, but a glance at figure 2 would suggest they’re not the dominant factor, and the correlation is strong. Whether this really is the explanation is, as far as I’m concerned, unknown. Correlation does not imply causation. But I see no reason to have to invoke strong positive feedback to explain the ‘wild swings’ of ice ages. Do you acknowledge that point?

    I haven’t read the other paper, but from what I can see from other reporting on it, all it says is that positive feedbacks would introduce uncertainty about sensitivity that could not be removed by better modelling. That positive feedback causes a form of instability that means there is no narrowly defined ‘sensitivity’, but that the actual temperature change that results will be largely random, always having some significant probability of huge positive swings. (Which is more or less what Coyote says above, I note.) I don’t see how that shows that there are large positive feedbacks. If they had actually determined the feedback so they could say it was strongly positive, then the sensitivity would no longer be uncertain.

    But perhaps you could expand on the evidence they offer, if that’s not the case?

  7. I find it very tiresome, to be honest, when someone looks at one paper and clearly hasn’t read the surrounding literature, and demands to be spoonfed evidence of things which have been known for decades. Well, if I must:

    It’s widely understood that changes in orbital configuration are strong drivers of climate change on very long timescales. The paper you found demonstrates that clearly. What’s interesting is that the magnitude of the changes caused is larger than can be explained by the orbital forcing alone. Also interesting is the pattern of a slow decline into an ice age, but very rapid return to non-ice age conditions. And the 100,000 year periodicity is related to the weakest orbital forcing, and yet it has the largest climate response. Basically, the climate response does not have the same shape as the forcing. See if your google skills will find you a way of explaining these observations without feedback processes, the sum of which is positive.

    So why haven’t you read Roe and Baker’s paper? Indifference? They don’t say what you think they say. They don’t say that positive feedbacks would introduce uncertainty, your nice paraphrase which implies some doubt about whether such feedback exist, but that (and I requote because perhaps you didn’t read it before): the uncertainty in the climate sensitivity in 2 x CO2 studies is a direct and general result of the fact that the sum of the underlying climate feedbacks is substantially positive. We know that the sum of the underlying climate feedbacks is substantially positive. You refuse to believe but then you haven’t read the literature.

    If they had actually determined the feedback so they could say it was strongly positive, then the sensitivity would no longer be uncertain – no. It’s a consequence of simple mathematics that a small uncertainty in the magnitude of the feedbacks converts into a large uncertainty in the temperature response.

  8. Thank you. Expand, if you will, on “the magnitude of the changes caused is larger than can be explained by the orbital forcing alone”. We have a 100 W/m^2 variation in forcing, which is about 25 times larger than proposed for 2xCO2. Can you show me some sort of “forcing versus temperature” graph that shows the temperature change a 100 W/m^2 and a 4 W/m^2 change in forcing would cause? How much temperature change can 100 W/m^2 explain, and by how much larger were the actual changes?

    Regarding the other features you mention – since positive feedback simply amplifies the response by 1/(1-f), positive feedback can’t explain changes in the shape of the response or weaker inputs causing stronger outputs either. What you need for that is something like time-dependent non-linearity, differential effects of heat distribution, hysteresis, and maybe resonant interactions with long time-period reservoirs of heat. There are many ways it could happen, and I see no obvious way in this remote era to decide between them. But all of that is getting off topic. The only question I’m interested in at the moment is whether the general magnitude is explainable, and the only element of the paper I consider relevant to that is the magnitude of the forcing.

    So why haven’t I read the Roe and Baker paper? Because I’d have to pay for it, and I don’t consider the price worth it. (Especially if I can persuade you to tell me what’s in it for free. :-)) I’ve read other abstracts and reports on it, and so far as I can tell, all they’ve done is to show that models using high positive feedbacks are inherently unstable, giving a spread of outputs looking similar to the uncertainties reported. That wouldn’t prove the feedbacks were strongly positive.

    Yes, I read the bit you quoted. But what I can’t tell from the quote is whether they are assuming the “fact” based on other sources (or dogma), or whether they are claiming their own research actually shows this. Since the IPCC is still classifying some of the feedbacks as having a low LOSU, and the models still use a wide range of values, my guess is that it’s an assumption, but I was willing to give the benefit of the doubt and ask you what evidence they use to justify the assertion, in case they had some. All you have done is to repeat the assertion.

    Your last paragraph I agree with.

  9. The price of having an informed opinion is not worth it? So you stick to your uninformed opinion. It’s a real shame you are not able to read the most important literature on the subject, and are reduced to hoping that random people on blogs might explain it to you. If you could read the papers you’d find the answers you seek, and you’d swiftly be disabused of your rather stupid suggestion that Roe and Baker might be assuming feedbacks exist because of ‘dogma’ rather than because there is ample evidence that they exist which is well documented in the literature.

    But perhaps even if you had access to the papers, you wouldn’t be reading them in the right way. It doesn’t look like you’ve read the IPCC reports, which are freely available and which would answer a lot of your questions. You certainly haven’t read the Roe paper properly, and you wonder about the difference between the 100 W/m² referred to therein, and the 4 W/m² from doubling CO2. Can I suggest you carefully read the caption on Figure 1 in the Roe paper, to find out exactly what the 100 W/m² figure is.

  10. “It’s a real shame…” Isn’t it though? Although the authors and journals don’t seem to express any obvious shame or embarrassment about it. Although I’ll pick you up on one point – I wasn’t really hoping you would explain it, I was offering you the opportunity to back up your assertions.

    However, if you don’t want to, or aren’t able to, I don’t have a problem with that.

    (And yes, I know what the 100 W/m^2 is – as I explained in the second paragraph of my first post. So?)

  11. So if you know what the 100 W/m² is, why did you think you could derive a climate sensitivity from it?

  12. Why do you think you can’t?

    The sensitivity is simply the ratio between the relevant input and the output. If ice ages are caused by heat distribution changes rather than changes in the total, then trying to figure out whether the cause is sufficient by looking at the global average is clearly the wrong thing to do. Little wonder you find you can’t explain ice ages, if you’re looking at the wrong variable.

    I specifically said it wasn’t comparable, and the only conclusion I drew was that it was “a massive perturbation”. Since the poles get about half their heat from the tropics, I expect you would be able to argue for a factor of two difference between global and local sensitivities – if those terms have any meaning – I’ll leave that to you. But I’d still be interested to see an accounting of why a 100 W/m^2 change at the boundary of the ice sheet wouldn’t be sufficient to make it grow.

    Since you’ve read and understood all the “ample evidence documented in the literature”, this should be a simple matter for you to summarise.

  13. Read up on the definition of climate sensitivity and you’ll find your answer.

    Your understanding will always be limited if you refuse to read the literature. And if you don’t even bother to try to learn for yourself it will be limited further. Why do you think your views are worth having when they are merely based on your own interpretation of other people’s interpretation of the science?

  14. Oh, yes. The definition of sensitivity. I do indeed find my answer.

    I’ve read a fair amount of the literature. But I’m not going to pay money to read one particular paper that I’m almost certain will tell me nothing I don’t already know. I’m pretty sure that if the paper contained anything as important as solid evidence that the feedback was large and positive, that the zealots would have made sure to get the information out there. We are supposed to believe they think this is a planetary emergency, that they are desperate for us to take urgent action, but they won’t let anyone see the evidence without paying?! No, if this was real the peer-reviewed original might be in a pay journal, but there would be lots of other explanations of the science out there as part of the persuasive effort. Instead, all you get are people telling you there’s masses of evidence, and we should be persuaded by it, but none of them can actually show you any. They tell you it’s in the IPCC report, except the IPCC report just asserts it and refers you to a paper, which refers you to another paper, which doesn’t seem to mention it. Or makes errors which, if you point them out, you get told that’s an old paper they’ve “moved on” from and there are plenty of other lines of evidence. You spend your entire time chasing through the labyrinth looking for “the evidence” while they’re busy changing the political world.

    I thought when you first posted the quote and I couldn’t get to the paper that you probably hadn’t read it either. Every time I ask what’s in it, and every time you fail to tell me, but simply repeat the assertions or tell me I should ‘go read the literature’, I become more and more sure of that. You’ve taken a quote without context and drawn grand conclusions on your interpretation of it, and now you can’t back it up.

    I find it interesting that you’re now saying that nobody who hasn’t read all the literature can have views worth having on the topic. Does that include Al Gore, politicians, environmentalist NGOs, the media, and virtually all of the other busybodies now telling us how to run our lives? You seem quite happy that they should make decisions based on defective understanding. What you’re effectively saying is that people either have to devote impossible amounts of their own time and money becoming initiated and accepted, or they have to trust the United Nations funded intergovernmental ‘scientific’ Authorities without question. This is, quite simply, Authoritarianism. Nullius in Verba, I say. The Emperor has no clothes.

    Why should I believe your interpretation of the science? Why should I think your views are worth having? You have been swift in the past to present us with other scientific snippets and explanations when it suited your case, why is it that after five separate requests for the evidence for there being large positive feedback, that you still can’t present it? What sort of evidence are your views based on?

  15. What an attitude! You won’t read the paper but you’ll just guess at its contents. You guessed wrongly, Stevo, and as a result you’re suffering from many basic misconceptions. I’ve explained what’s in the paper already, but clearly you’re too fucking stupid to listen – or you’re just trolling. If you don’t think I’ve explained it, well, you’ll have to just buy access to the bloody thing, won’t you. It’s really quite straightforward. You seem very aggrieved that journals don’t give away their content for free to anyone and everyone – why should they? You demand to be spoonfed evidence of feedbacks when despite all the evidence there is (some of which I’ve already told you), you refuse to accept it, and just stick your fingers in your ears and shout ‘LA LA LA I CAN’T HEAR YOU NO FEEDBACKS LA LA LA’.

    Oh, and how you miss the point. Don’t believe my interpretation of the science. Don’t believe anyone’s interpretation of it. Read the science yourself, you fool, and interpret it yourself, if you’re capable of understanding it. If you’re not, then refrain from having an opinion. There is no reason why climate science should be simple enough for morons to understand. If it would take impossible amounts of time and money for you to get to grips with the science, shouldn’t that tell you that the science is beyond you and you’d be better off leaving it to people for whom this is not the case?

    Listen, I was ill recently. I went to the doctor and explained my symptoms. He gave me some medicine. It would have taken me impossible amounts of time and money to research my condition myself. All the medical journals require subscriptions and medical text books are ridiculously expensive. Even if I had researched it all myself, I could easily have come to the wrong answer through my lack of specific training. So, I trusted the doctor. This was a wise decision, the remedy was appropriate, and I am in good health now. You seem to be of the opinion that lack of training in science doesn’t matter at all, that you could understand all the science, if only those bastard journals would give everything away for free. Do you not see that your position is slightly ridiculous?

  16. Oh dear! I seem to have struck a raw nerve!

    Let’s see. The F-word. Stupid. Bloody. Moron. Bloody. The language of a responsible and respectable “scientist”. Who appears upset that he’s been caught out making stuff up.

    I’m not at all aggrieved that journals keep their contents private – but until the evidence is published somewhere I can see it, I’m not going to accept it. If I told you that I had a marvellous proof that AGW was false, and you could see it for only $500, would you pay up? Or would you simply accept that whatever I said was true, if I was a suitably august authority? Like I said, it’s not the fact that the journal article is pay-per-view, it’s the fact that the information isn’t promulgated elsewhere. It’s the fact that the only place you can apparently find it is by playing the endless game of hunt-the-reference among the journals.

    All you have to do is to provide a short summary of the observational evidence and the chain of reasoning by which it is determined that feedbacks have to be large and positive, and that there are no inconvenient unquantified negative feedbacks like clouds cancelling them all out. I know that there is no such proof. Prove me wrong if you can.

    Nobody can keep up with everything published in a field, even professionals. They rely on their social networks to hear about the important stuff, about what is worth paying attention to. I’ve read plenty of papers, and I most definitely have been trained in science, but you think not having read this one paper renders me entirely unqualified to comment? Certainly, there’s no sign that you’ve read it either, which would seem to render you unqualified too, wouldn’t it?

    Your doctor example is very good, though. It explains the difference between being rational, and following the scientific method. When an immediate action is forced and insufficient information is available, then it is rational to use fallacious reasoning like appeals to authority and correlation implying causation to come to a decision, but it is not scientific. Fallacies are so commonly believed because they do often increase the odds of making the right decision, but they’re still fallacies. It is not unreasonable for a politician to listen to the experts. But they do so as a politician, not a scientist. The scientific method is founded on rejecting these fallacies, and only accepting experimental evidence. Nullius in Verba. On Nobody’s Word.

    Science was founded in the rejection of the authority of the Church and Aristotle and the other classics. Prior to that, they believed that the path to knowledge was to listen to the experts and take their word for it. Scholarship was about how much you had memorised, how many books you had read, whose student you had been. And then people like Galileo, Descartes, Bacon, and Newton came up with a new approach. Appeal to Authority was recognised as the fallacy it is, and rejected. It is still in use elsewhere, but not in science. It is, as much as anything is, the very opposite of science.

    To follow your medical analogy – it is not the patient who is making an appeal to authority, but someone claiming to be a doctor. “I’m prescribing leeches for your condition… How do they work? That’s explained in Galen, you know… Yes, I know it’s in Latin… No, I won’t translate, and no I don’t know the precise explanation – but it’s Galen. If it wasn’t true, you wouldn’t have had thousands of doctors all across Europe following it for the past five hundred years, would you now?”

    You claim to be a scientist, and then have the outrageous medieval effrontery to try to justify the Appeal to Authority to me?! Ha!

  17. until the evidence is published somewhere I can see it, I’m not going to accept it – you can see it if you want. $10 is not a lot of money to pay to avoid being ignorant. If you don’t have access to journals like Science, then I strongly suspect that your claim to have read plenty of papers is bullshit.

    It’s your choice not to read this particular paper (and all the others). It’s also your choice to vent forth with an opinion, despite your wilful ignorance. It’s my choice to be rude to people who think they have a valid opinion on a scientific subject when they admit they don’t read the literature.

    You want to know about all the evidence for feedbacks? It’s all in the literature. You can find it if you want to. But I know you don’t want to.

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