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Climate response estimates from Lewis & Curry

Guest commentary from Richard Millar (U. Oxford)

The recent Lewis and Curry study of climate sensitivity estimated from the transient surface temperature record is being lauded as something of a game-changer – but how much of a game-changer is it really?

The method at the heart of the new study is essentially identical to that used in the much discussed Otto et al. (2013) study. This method uses a simple equation of the energy balance of the climate and observations of global temperature change and estimated ocean heat uptake anomalies along with a time series of historical radiative forcing (code), in order to make inferences about the equilibrium climate sensitivity (ECS – the ultimate equilibrium warming resulting from doubling carbon dioxide concentrations) and its shorter-term counterpart the transient climate response (TCR – the warming at point of doubling after carbon dioxide concentrations are increased at 1% per year). [Ed. An overview of different methods to calculate sensitivity is available here. The L&C results are also discussed here].

Lewis and Curry use an updated radiative forcing estimate over that used in Otto et al along with slightly different assumptions over the periods used to define the observational anomalies. They use the latest IPCC numbers for radiative forcing and global temperature changes, but not the latest IPCC ocean heat content data. Their result is a 5 – 95% confidence interval on ECS of 1.1–4.1K and for TCR is 0.9-2.5K. These confidence intervals are very consistent with other constraints, from paleo or emergent observations and with the range of GCM estimates. For the TCR, arguably the more important measure of the climate response for policy makers as it is a better predictor of cumulative carbon budgets, the 5-95% confidence intervals are in fact almost identical to the AR5 likely range and similar to the CMIP5 general circulation model (GCM) estimated 5–95% range (shown below).

Figure 1: The 5-95% confidence ranges for transient climate response (TCR) taken from various studies as in Fig. TS.TFE6.2 of IPCC AR5 WG1. The green bordered bar at the top of figure is the estimated 5-95% range from the CMIP5 GCMs. blue bordered bar at the top of the figure is the 5-95% range from the Lewis and Curry (2014) study. The grey shading represents the AR5 consensus likely range for TCR.

There is a difference between the Lewis and Curry 17-83% confidence intervals and the IPCC likely ranges for TCR and ECS. However, for all quantities that are not directly observable, the IPCC typically interprets the 5-95% confidence intervals as likely ranges to account for the possibility that the model used to derive the confidence intervals could be missing something important (i.e. non-linearity that would not be captured by the simple models used in Otto et al and Lewis and Curry, which can particularly be a problem for ECS estimates using this method as the climate feedback parameter is assumed to be constant in time) [IPCC AR5 WG1 Ch10.8.2]. In this case, accounting for more complete surface temperature changes (Cowtan and Way, 2013), or the hemispheric imbalance associated with aerosol forcing (Shindell, 2014), or updates in the OHC changes, may all shift the Lewis and Curry distribution. [Ed. This expert judgement related to structural uncertainty was also applied to the attribution statements discussed here before].

The median estimate of the TCR from Lewis and Curry (1.3K) is towards the lower end of the IPCC likely range and lower than the CMIP5 median value of around 1.8K. A simple way to understand the importance of the exact TCR value for mitigation policy is via its impact on the cumulative carbon budget to avoid crossing a 2K threshold of global surface temperature warming. Using the Allen and Stocker relationship between TCR and TCRE (the transient climate response to cumulative emissions) we can scale the remaining carbon budget to reflect different values for the TCR. Taking the IPCC CO2-only carbon budget of 1000 GtC (based on the CMIP5 median TCR of 1.8K) to have a better than 2 in 3 chance of restricting CO2-induced warming to beneath 2K, means that emissions would have to fall on average at 2.4%/year from today onwards. If instead, we take the Lewis and Curry median estimate (1.3K), emissions would have to fall at 1.2%/year. If TCR is at the 5th percentile or 95th percentiles of the Lewis and Curry range, then emissions would need to fall at 0.6%/year and 7.1%/year respectively.

Non-CO2 emissions also contribute to peak warming. The RCP scenarios have a non-CO2 contribution to the 2K peak warming threshold of around 0.5K [IPCC AR5 WG1 – Summary for Policymakers]. Therefore, to limit total warming to 2K, the CO2-induced contribution to peak warming is restricted to around 1.5K. This restricts the remaining carbon budget further, meaning that emissions would have to fall at 4.5%/year assuming a TCR of 1.8K or 1.9%/year taking TCR to be equal to the Lewis & Curry median estimate of 1.3K (assuming no mitigation of non-CO2 emissions).

While of some scientific interest, the impact for real-world mitigation policy of the range of conceivable values for the TCR is small (see also this discussion in Sci. Am.). For targets like the 2 K guide-rail, a TCR on the lower end of the Lewis and Curry and IPCC ranges might just be the difference between a achievable rate of emissions reduction and an impossible one…


  1. N. Lewis, and J.A. Curry, "The implications for climate sensitivity of AR5 forcing and heat uptake estimates", Climate Dynamics, vol. 45, pp. 1009-1023, 2014.
  2. A. Otto, F.E.L. Otto, O. Boucher, J. Church, G. Hegerl, P.M. Forster, N.P. Gillett, J. Gregory, G.C. Johnson, R. Knutti, N. Lewis, U. Lohmann, J. Marotzke, G. Myhre, D. Shindell, B. Stevens, and M.R. Allen, "Energy budget constraints on climate response", Nature Geoscience, vol. 6, pp. 415-416, 2013.
  3. K. Cowtan, and R.G. Way, "Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends", Quarterly Journal of the Royal Meteorological Society, vol. 140, pp. 1935-1944, 2014.
  4. D.T. Shindell, "Inhomogeneous forcing and transient climate sensitivity", Nature Climate Change, vol. 4, pp. 274-277, 2014.
  5. P.J. Durack, P.J. Gleckler, F.W. Landerer, and K.E. Taylor, "Quantifying underestimates of long-term upper-ocean warming", Nature Climate Change, vol. 4, pp. 999-1005, 2014.
  6. M.R. Allen, and T.F. Stocker, "Impact of delay in reducing carbon dioxide emissions", Nature Climate Change, vol. 4, pp. 23-26, 2013.

236 Responses to “Climate response estimates from Lewis & Curry”

  1. 101

    #99–Doug, I’m not sure I accept your premise that ‘most climate scientists’ are espousing sensitivity values ‘one-half to two-thirds of the earlier best estimate,’ though I agree that if sensitivity were lower that that would qualify as good news.

    I’d read AR 5, which lowers sensitivity estimate a bit. Assuming that we are talking about ECS, a relevant passage from Chapter 12 says:

    ECS is likely in the range 1.5°C to 4.5°C with high confidence. The combined evidence increases the confidence in this final assessment compared to that based on the observed warming and paleoclimate only. ECS is positive, extremely unlikely less than 1°C (high confidence), and very unlikely greater than 6°C (medium confidence). The upper limit of the likely range is unchanged compared to AR4. The lower limit of the likely range of 1.5°C is less than the lower limit of 2°C in AR4.

    So the lower limit is three-quarters of the previous estimate, and the upper limit unchanged.

    But one of the unavoidable flaws in Assessment Reports is that the production time is long. So I searched Google Scholar for papers published this year on the topic and the first link I clicked had this to say:

    Equilibrium climate sensitivity measures the long-term response of surface temperature to changes in atmospheric CO2. The range of climate sensitivities in the Intergovernmental Panel on Climate Change Fifth Assessment Report is unchanged from that published almost 30 years earlier in the Charney Report.

    That’s Urban et al, found here:;jsessionid=E0ABEB8CEB3FFC3E970822AD02ECC348.f02t01?deniedAccessCustomisedMessage=&userIsAuthenticated=false

    There is, however, Skeie et al, here:

    The posterior mean of the ECS is 1.8 °C, with 90% C.I. ranging from 0.9 to 3.2 °C, which is tighter than most previously published estimates.

    That’s reasonably close to two-thirds lower.

    Troy Masters weighs in (in Climate Dynamics) with a 1-sigma range of 1.5-2.9:

    That, too, is roughly along the lines you propose.

    There’s a methodological paper from Huber et al that’s worth noting. It doesn’t give an actual estimate, if I’m understanding it correctly, but it does have an illuminating summary comment:

    …the likely range for ECS has been rather robust in the past decades [Knutti and Hegerl, 2008]. Yet the quest for a tighter uncertainty range of equilibriumclimate sensitivity recently gained new momentum when studies used the updated observed surface and ocean warming together with energy budget equations [Otto et al., 2013] or reduced complexity climate models [Aldrin et al., 2012; Lewis, 2013] and found values near the lower end of the previously long-standing likely range to be more plausible. In contrast, the current generation of fully coupled climate models of the Coupled Model Intercomparison Project 5 (CMIP5) as well as recent estimates from the paleorecord show still a mean estimate of about 3.2°C (±1.3°C, 90% uncertainty) [Forster et al., 2013] and a range of 2.2–4.8°C [Rohling et al., 2012], respectively. The reason for the different modes for ECS (i.e., median) across different studies, methodologies, and models is still unclear.

    So perhaps what you are seeing as ‘most climate scientists’ is actually a particular subset of studies–the ones using “energy budget equations… or reduced complexity climate models.” It’s worth noting that both the Skeie and Masters studies use energy balance models.

    But what about TCR? There’s a paper from Drew Shindell that has this to say:

    Understanding climate sensitivity is critical to projecting climate change in response to a given forcing scenario. Recent analyses have suggested that transient climate sensitivity is at the low end of the present model range taking into account the reduced warming rates during the past 10–15 years during which forcing has increased markedly. In contrast, comparisons of modelled feedback processes with observations indicate that the most realistic models have higher sensitivities. Here I analyse results from recent climate modelling intercomparison projects to demonstrate that transient climate sensitivity to historical aerosols and ozone is substantially greater than the transient climate sensitivity to CO2.This enhanced sensitivity is primarily caused by more of the forcing being located at Northern Hemisphere middle to high latitudes where it triggers more rapid land responses and stronger feedbacks. I find that accounting for this enhancement largely reconciles the two sets of results, and I conclude that the lowest end of the range of transient climate response to CO2 in present models and assessments (less than 1.3 C) is very unlikely.

    That’s here:

    So, a similar split in TCR investigations. I’m afraid that it seems to me that you are over-interpreting some recent papers when you conclude that there is a dramatic lowering of sensitivity estimates overall.

    Too bad. It would be nice if we indeed had more time to address the crisis.

  2. 102

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  3. 103
    Chris Dudley says:

    Kevin (#97),

    Your claim to a hand wave is well put. 2014 being a record is non-informative regarding an “end-to-warming.” If there were a long term plateau in the offing, we’d still expect quite a few more record warm years. We’d expect even more for no long term plateau but that is not important for the occurrence in s single year.

    One place where there may be a little statistical leverage is answering the question “Aren’t we due for a dip rather than a pause if the underlying trend has changed?” But, a new record warm year is expected to occur in any scenario.

  4. 104
    Victor says:

    MARodger #100:
    Yes, I saw that sea level graph when you first posted the link. (And by the way, your first link takes us to the same CO2 graph as your second link.) The CO2 graph is interesting, yes. But it seems to me you are taking the “A” in AGW too literally. After all, we anthropods have been sending CO2 into the atmosphere since the origin of the species. We exhale it for one thing. Lots of it over a lifetime. And the more of us there are, the more exhalations take place. We’ve also been known to set forest fires. Not only for slash and burn agriculture but long before that, as an efficient (if wasteful) hunting technique. They don’t call it “Tierra del Fuego” for nothing. (And, of course, animals also exhale — and lots of fires are started by lightning.) Sure, anthropogenic atmospheric warming began long before the Industrial Revolution. Here’s another CO2 graph that breaks things down in a bit more detail:

    You’ll note that deforestation goes all the way back to 1750, and no doubt many thousands of years before that, as I’ve reminded you. So what? Yes, literally if it’s caused by humans it’s “anthropogenic.” But I thought the topic at hand was emissions produced by fossil fuels. And if you want to establish that fossil fuel emissions are causing sea level rise then you need to establish a correlation between sea level rise and CO2 produced by fossil fuel emissions, not “anthropogenic” sources in general. Since the map you’ve provided tells us nothing about such emissions, we can turn to the one I’ve provided, which does. According to that map, these emissions don’t really show up on the radar until after 1850.

    Yet, according to the graph you yourself provided earlier (now on my blog), we see a distinct rising trend in sea levels dating from before 1800. That one obviously wasn’t caused by the burning of fossil fuels. Nor is it likely the later rising trend dating from around 1860 was either, given the unlikelihood such emissions at such an early stage affected sea levels at all, and, if so, then so soon.

    So I’m sorry, despite the existence of some sort of correlation between AGW, taken literally, and sea level rise, I fail to see a similar correlation involving fossil fuel usage. And as far as temperatures are concerned, as indicated in the graph I’ve reproduced on my blog (, we see various uptrends and downtrends, while the rate of CO2 emissions remains steady. Again, no real correlation. Unless you want to take things 100 years at a time as you (jokingly I presume) suggest.

  5. 105
    MARodger says:

    Victor @104.
    I won’t dwell on the nonsense you present @104 other than point out a few of the incongruities.
    For instance @104 you tell me “Yes, I saw that sea level graph when you first posted the link.” Don’t you think that sits very awkwardly with your comments @79 & ‘@95? Those comments strongly suggest the link to “that sea level graph” @40 had entirely passed you by.
    Or the nonsense you raise @104 about human breath being a source of AGW. Perhaps you should get on to the IPCC and put them straight! Or the sudden distinction you now present that it is all about FF emissions of CO2 and nothing else matters. Perhaps you should get on to the IPCC and put them straight! Or your reversion back to your bobble-analyses. My my! Perhaps you should get on to the IPCC and put them straight!
    The graph you found, by-the-way, is rather out-of-date and simply adding Houghton to the already mentioned Boden et al. with a couple of linear trends drawn in to fill in the gaps.

    When I wrote @100 The short answer would be “Stick to century-long trends and ignore the detail if you wish to avoid playing the fool some more.”, I had assumed even you would have noted that this was concerning the Temperature-SLR relationship. I expected you would take on board that the GHG-Temperature relationship is not involved. My apologies. I was wrong because @104 you did manage to conflate these two distinct relationships. Well done you!
    And was I joking about century-long trends as you “presume”? No I was not.
    So let’s talk SLR but let’s forget your decadal bobbles. Let’s ignore my centenial wobbles. Let’s talk multi-millennial/mega-millennial mega-wobbles.

    Concerning SLR, consider this little gem.
    At the last glacial maximum, global temperature was about 6ºC lower than modern times. And sea level was 120m below modern times. Nothing contentious here. Note the ratio. 20m/ºC.
    And at the start of the Oligoccene about 33 million years ago, we see the onset of major polar glaciation at a time when sea level would have been not a long way from 80m higher than today and global temperature some 6ºC higher. Nothing so contentious here. Note the ratio. Something approaching 13m/ºC.
    Now, since pre-industrial times, the global temperature rise has been not far short of 1ºC. So Victor, given the ratios just calculated, where is our multi-metre SLR?

  6. 106
    patrick says:

    On the hiatus…

    “Excellent discussion by Carl Mears on RSS record and reasons for model/obs discrepancies”:

    –Gavin’s recent tweet.

  7. 107
    Victor says:

    #105 MARodger

    Obviously we’ll never agree on the cause-effect issue, but I’m wondering what your thoughts are on the policy issue. I’ve written some additional posts regarding policy that I invite you (or anyone else reading here) to consider. Specifically:


  8. 108
    MARodger says:

    Victor @107.
    You first appeared on this thread @36 proclaiming that you were not a denier because you were a “a card carrying lifelong Democrat, liberal to the gills.” Whatever you politics, it is evident from your comments since #36 that you are indeed in denial over AGW. How else is anyone to interpret your comments here? You are completely unable to give cogent reason for your repeated assertions that (directly or indirectly) AGW is a trivial non-problem.
    As an example of this (@107 you invite me to give my thoughts), concerning an EU agreement to reduce annual emissions by a further 0.5 GtCO2(e) over the next 15 years, adding to the EU programme of 1.5 GtCO2(e) cuts already in place, you consider that it “will do little to ameliorate global warming and sea level rise.” And even that statement is hedged by the caveat “assuming they (ie GW & SLR) are in fact caused by fossil fuel emissions.” Reasons given for making such a statement – none!!
    Once you fight your way outside the denialistic paradigm, there is no denying these views on AGW present pure denialism.

    Victor, this is a website that deals with climate science. Our hosts are climate scientists. It is not the place to mouth off with nonsensical opinon about AGW.
    And this thread has a specific subject. It is concerned with the “Climate response estimates from Lewis & Curry” . It has probably passed you by, but while you were pronouncing on the subjects of SLR/OHC, temperature and climate forcing/CO2, you were at least discussing the data used by Lewis & Curry and were thus arguably on topic. To attempt to start a chat about what you term “the policy issue” is well off-topic in this thread. And I would add that such chatter, even when supported evidentially, is not greatly appreciated on this website, and on occasion that has even been the express policy on the open thread.

  9. 109
    Victor says:

    Re 108, MARodger

    I don’t consider myself a denier because, judging from what I’ve read on so many sites such as this, those labeled “deniers” are assumed to be motivated by ideology rather than purely scientific concerns. As a liberal, my skepticism regarding AGW has nothing to do with my ideology, which is far to the left of center. In your eyes anyone who disagrees with your take on g.w. is, by definition, a denier. That’s your problem, not mine.

    Your consistently insulting responses smack more of 8th grade level bullying than serious reasoning. Your responses are also obviously defensive, which tells me that deep down you have doubts of your own, deeply repressed, but real. How could you not, given the many serious holes in the mainstream view?

    I have a lot of experience dealing with fellow academics, in both the sciences and humanities, though not in this particular realm, and have always had a healthy skepticism regarding their many certainties. I’ve read a great many studies where much has been made of neat looking correlations without much effort to critically analyze their meaning. But rarely have I seen so many efforts to explain away the LACK of correlation as in the current state of climate science.

    I invite you to read the following website,, a particularly illuminating discussion of Occam’s Razor by Francis Heylighen:

    “Though [Occam’s Razor] may seem rather trivial, it is essential for model building because of what is known as the “underdetermination of theories by data”. For a given set of observations or data, there is always an infinite number of possible models explaining those same data.”

    Whenever I read the many efforts to explain away the hiatus, and other anomalies related to the g.w. orthodoxy, I think of Heyhlighen’s brief but devastating formulation.

    As for the policy aspect, it’s related to this thread as much as all the other threads on this blog, because it concerns what we are to DO about AGW, assuming it’s real after all.

  10. 110
    Hank Roberts says:

    > Victor … fellow academics

    In what academic field do you claim expertise? Economics?
    When was the year of your most recent publication?

    On your linked blog you cite “Climate Depot” as a source — do you consider that a reliable source? Why? Have you any reason to consider it reliable?

    It doesn’t matter which direction you’re out from the scientific center, there are people far left, far right, and so far out they meet and overlap — who rely on sources like that one.

    As an academic, you should be able to talk to people in the physics, chemistry, and biology departments, and use their departmental libraries.

    What have you read? Who do you consider reliable?

  11. 111
    Ray Ladbury says:

    Victor, we have something in common: Neither of has any idea what you are talking about. The “Pause” is not being modeled. It is being explored. It is natural to assess multiple hypotheses during that phase of investigation.

    Your misunderstanding of scientific method is just as profound as your misunderstanding of the significance of the distinction between fossil carbon and that already in the system.

    Your political ideology doesn’t protect your from delusion. Alexander Cockburn was a denialist, and he was far to the left of you. Look at the evidence…all of it.

  12. 112
    SecularAnimist says:

    Victor wrote: “I don’t consider myself a denier because … those labeled “deniers” are assumed to be motivated by ideology rather than purely scientific concerns.”

    People are labeled “deniers” because they deny known facts and overwhelming evidence, and instead assert known falsehoods and conjectures that are at best unsupported, and at worst contradicted, by overwhelming evidence. Motivation is irrelevant.

    Your assertion about “the LACK of correlation as in the current state of climate science” is a good example of asserting a known falsehood.

    It’s a falsehood that you have repeated here multiple times, even after numerous commenters have demonstrated to you that it is false.

    And your continuing attempt to legitimize your so-called “skepticism” (which is really not skepticism at all) by claiming to be a “liberal” is still an ad hominem fallacy, no matter how many times you repeat it.

    Your political views are irrelevant. What is relevant is that you deny known facts and assert known falsehoods — and that you do so repeatedly even after you have been corrected, which suggests that your falsehoods are deliberate.

  13. 113
    Mal Adapted says:

    Victor, I visited your website, and I say MARodger is right to call you a denier. That is demonstrated by your “skepticism regarding the alleged causal relation between greenhouse gas emissions and global warming” which is is at odds with the overwhelming expert consensus, and your belief that Al Gore is responsible for the urgency of calls to curtail GHG emissions.

    Your self-identification as “a card carrying lifelong Democrat, liberal to the gills” obviously hasn’t protected you from the Dunning-Kruger effect. On complex scientific topics, a genuine skeptic, who hasn’t put the time in to become an expert himself, recognizes that there may be people who know more than he does. That you lack the scientific meta-literacy to identify those people doesn’t justify your cavalier dismissal of “the mainstream view”.

    As for MARodger’s “insulting” responses: his comments are well within the boundaries of legitimate scientific discourse. That you are so easily insulted is your problem, not his.

  14. 114
    MARodger says:

    Mal Adapted @113.
    Myself, I don’t think I would consider my “insulting” responses to be well within the boundaries of legitimate scientific discourse” except in that they reflect the egregious and unsubstantiated statements I was responding to. I was also laying it on a little thick because I felt it might get a normal person to knuckle down and start thinking outside that denialist bubble. So I would perhaps agree that my responses were “within the boundaries of legitimate scientific discourse” given the circumstances.

    What perplexed me however was that I wasn’t sure why (as is stated @109) my responses should be considered “obviously defensive” or how it could be true that “deep down” I have “deeply repressed … doubts.” But then it occurred to me that within the black and white world which a denialist inhabits, if I do have doubts, which is thus tantamount to being truly wrong, that means … now I must be sure to put this correctly … there’s a lot of nuanced and complex logic in this … if I am wrong that means Victor must be right!!
    Now that understanding sort of colours the situation rather a lot. Very conforting to know.

  15. 115

    SA said:

    People are labeled “deniers” because they deny known facts and overwhelming evidence, and instead assert known falsehoods and conjectures that are at best unsupported, and at worst contradicted, by overwhelming evidence. Motivation is irrelevant.

    Exactly. In the current case, insisting on the paramount importance of an invalid measure of correlation (invalid because it ignores the issue of statistical significance), in a single metric of warming (by ignoring everything except the TLT record), over a single time of record (ignoring whether that timespan is suitably chosen), and ignoring pretty much everything that dynamic analysis has to offer, in the face of repeated, well-sourced, and corroborated commentary on the analytic inadvisability of doing these things, is pretty much textbook denial.

    Quite disappointing, really.

  16. 116
    Hank Roberts says:

    Victor, you make much of the REMSS TLT chart from Morano’s Climate Depot.

    But you omit what REMSS says about that data.
    You can look this stuff up for yourself.
    That’s what’s missing from your blog: skepticism about the sources you rely on. You’re reblogging ideas from political PR sites’ interpretations.

    Here’s what you’ll find if you search on the REMSS data:

    The recent slowing in the rise of global temperatures …
    Sep 22, 2014 – Does this slow-down in the warming mean that the idea of anthropogenic global warming is no longer valid? The short answer is ‘no’.

  17. 117
    Victor says:

    So. A barrage of ad hominem attacks. On a science blog. Interesting.

    Stick to the science, folks, and we’ll get along fine. While MARodgers has been insulting, he’s also raised genuine scientific issues, to which I’ve been willing to respond. I’m usually willing to take the insults in stride, but this is too much. Let’s get back to the science, please.

    As far as my credentials are concerned, I’m a social scientist, with a strong interest in anthropology, semiotics and theory of the arts. I’ve published several papers in peer reviewed journals of semiotics, anthropology and the arts of painting, film and music. A recent book, soon to be re-issued in an Italian translation, deals with the pre-history of human culture from the perspective of population genetics. So no, I’m neither a climate scientist nor a physicist. But I am a student of the philosophy of science and I do think I know something about scientific method.

    As for my use of Climate Depot “as a source” — well, I didn’t really use it as a source. All I did was reproduce a graph posted on that site. The graph wasn’t produced by anyone at Climate Depot, it’s an RSS graph, clearly labeled as such. More defensiveness, I’m afraid.

    As for “the science,” my initial post was prompted by a NASA report authored by climate scientists, a report that called into question one of the most commonly seen theories regarding global warming, the notion that most of the “missing” warmth is stored in the deep ocean. This report also noted that upper ocean warming has not been sufficient to account for the hiatus.

    Neither I nor the NASA scientists are the only ones pointing to the hiatus as a problem. A great many climate scientists see it that way as well. See, for example the following, by Jeff Tollefson:

    If I “deny known facts” then so do a great many climate scientists who’ve become skeptics in recent years. This is not by any means a debate between amateurs and “real scientists” — it’s a debate also being waged among the scientists themselves. My angle on this concerns the scientific principles behind the debate, not the science itself. Which is why I pointed to the Heylighen post on Occam’s Razor. If you want to talk scientific principles, let’s discuss that.

    NONE of the evidence I’ve presented comes originally from me. Everything comes from the scientific literature. All I’ve done is offer some interpretation, based on my understanding of fundamental scientific principles.

    As far as Al Gore is concerned, my problem is not with his take on the science, which was, and is, perfectly understandable, but with his take on what is to be done in response — which I regard as a pipe-dream, yes. And a dangerous one. Public policy is NOT climate science, and climate scientists have no special expertise when it comes to social science, economics, politics and human nature. Yet a great many have taken it upon themselves to instruct the rest of us on how we should lead our lives in the coming years, i.e., that we should be willing to impoverish ourselves on the basis of unsubstantiated claims of imminent doom. Sorry but I’m not buying it.

  18. 118
    Victor says:

    #116 Hank Roberts

    Thanks for the link to the Mears article “explaining” the hiatus. Here’s a quote:

    “The truth is that there are lots of causes besides errors in the fundamental model physics that could lead to the model/observation discrepancy. I summarize a number of these possible causes below. Without convincing evidence of model physics flaws (and I haven’t seen any), I would say that the possible causes described below need to be investigated and ruled out before we can pin the blame on fundamental modelling errors.”

    I certainly agree that other causes need to be investigated. However, to once again quote Heylighen:

    “Though [Occam’s Razor] may seem rather trivial, it is essential for model building because of what is known as the “underdetermination of theories by data”. For a given set of observations or data, there is always an infinite number of possible models explaining those same data.”

    A good example is the Ptolemaic theory of the universe, where anomalies in the various orbits were accounted for by those famous epicycles.

  19. 119
    SecularAnimist says:

    MARodger wrote: “I wasn’t sure why (as is stated @109) my responses should be considered ‘obviously defensive’ …”

    Crowing that one’s opponent is “on the defensive” is an ancient troll gambit that was old when USENET was young.

    It is typically used when the opponent has just demolished the troll’s arguments, and the troll is stalling for time to come up with a response that will allow him to “save face”.

  20. 120
    MARodger says:

    Victor @117.
    Where is this “science blog” you refer to with the “barrage of ad hominem attacks”?
    I ask because I do not see any such attacks here.

    Your repeated reference to Ockham’s razor is suggesting an eagerly held view that AGW can be interpreted in more than one way. How so? If you don’t explain, it will be left to others.

    My own interpretation (and treading carefully so as not to pick up Ockham’s broom by mistake) is to use Ockham for a ruling, not on “an infinite number of possible models” which would be rather time-consuming, but on the two competing models being discussed here.

    Model 1 – The science presented by IPCC AR5 (which includes Box 9.2 ‘Climate Models and the Hiatus in Global Mean Surface Warming of the Past 15 Years’) is exactly what it says it is on the cover. It presents a proper evidence-based account of the then-current human knowledge of AGW which shows mankind to be certainly in the do-do and very likely deep in the do-do. However, this is a finding that is rejected by many but this rejection is always for non-scientific and unfounded reasons.
    Model 2 – There are “many serious holes in the mainstream view” with “a great many climate scientists who’ve become skeptics in recent years” yet who have failed to prevent a whitewash within IPCC AR5 which should have informed the world that there is actually a great deal of doubt that mankind is in any sort of do-do whatever. Not only that, these “great many climate scientists” have entirely failed to communicate their ‘sketpical’ presence either scientifically or within the media and their very existence along with those “many serious holes in the mainstream view” remain entirely obscure except to the occasional great intellect, like Victor@117, whose “understanding of fundamental scientific principles” allows him to see the true situation and thus probably also see what it is (a grand conspiracy perhaps?) keeping the truth from being exposed.

    I would suggest it is not difficult to pronounce Model 1 as the survivor with Model 2 left bleeding out on the floor.

  21. 121
    Mal Adapted says:


    So. A barrage of ad hominem attacks. On a science blog. Interesting.

    Ad hominem would apply if we rejected your scientific arguments not on their merits but on the basis of your personal characteristics. But we’ve already evaluated your principle scientific arguments on their merits, and rejected them because they’re deficient. If you continue to make them after it’s been explained to you why they’re incorrect, we are bound to assume it’s for non-scientific reasons. From the evidence we’ve seen, you appear to be influenced by one or more cognitive biases. What you are calling ad hominem attacks are intended to elucidate those biases. Our conclusions about them may or may not be correct, but they’re not about the merits of your scientific arguments so they’re not argumenta ad hominem.

    Really, Victor, all you have to do is acknowledge to yourself that you’re over your head here. The aggregate expertise among RC participants is enormous. If you treat it as a resource for learning about climate science, you might improve your own understanding.

  22. 122
    Victor says:

    #120 MARodger

    When invoking Occam’s razor I wasn’t referring to the two models you’ve presented, but to the many different attempts to account for the hiatus, and other anomalies. As Heylighen notes, there is an infinite number of theories that could account for any given set of facts. So it’s not enough to come up with a theory that accounts for the anomalies, one has to demonstrate that one’s theory does not violate Occam’s razor, which was designed to pare down the number of possible explanations until we arrive at the most “parsimonious.” I.e., the most likely.

    Lets take Occam at his word: “Pluralitas non est ponenda sine neccesitate” i.e., “plurality should not be posited without necessity.”

    In other words, a plurality of causes should not be posited unless one has demonstrated the necessity of doing so. In terms of our present debate, any theory offered to account for the anomalies (such as the hiatus) must not only offer reasons that might possibly account for them, but demonstrate the necessity for offering only those reasons and no others.

    The various explanations I’ve seen offer reasons, yes, but say nothing to help us understand why these reasons and these reasons only are necessary to fully explain the anomalies. I get the impression mainstream climate scientists seem to think: the more explanations the better. But since, as we’ve learned, there are an infinite number of possible explanations, the “more the merrier” principle won’t work.

    As I see it, the only explanation I’ve seen so far that satisfies Occam’s razor is falsification, which requires no “pluralitas” at all.

  23. 123
    Victor says:


    “But we’ve already evaluated your principle scientific arguments on their merits, and rejected them because they’re deficient. If you continue to make them after it’s been explained to you why they’re incorrect, we are bound to assume it’s for non-scientific reasons.”

    You could say the same to anyone who disagrees with you. I could say the same about you. What you are actually saying is “I’m right and anyone who can’t see that is unqualified to express an opinion.” Why waste time with pronouncements of that sort?

    While I certainly respect the technical expertise of climate scientists in matters pertaining to climate science per se, that doesn’t mean I have to accept their interpretation of the evidence they’ve uncovered. I would never presume to challenge the validity of that evidence, because I lack that expertise. Climate science is about digging into the evidence and attempting to come up with facts and that requires a solid grounding in the science. As does producing models to help us understand the facts. But the interpretation of that evidence and those facts and those models is another story entirely.

    A case in point is the meaning of the aporia of quantum physics. For a long time, physicists rejected the necessity of an interpretation expressly because, as they saw it, an interpretation didn’t concern them — it was metaphysics, not science. In the case of climate science, however, policy issues are at stake, so one can’t simply withdraw into “the science,” one has to interpret one’s results, to understand their meaning and offer advice on what is to be done. And at this point, “the science” is no longer enough. The responsibility of the scientists is to present their facts and models as clearly as possible so those in a position to properly interpret them may best do so.

    And of course, scientists certainly have the right to interpret their own results as well. But they have no right to insist that they are the only ones qualified to do so.

  24. 124
    MARodger says:

    Victor @122.
    I don’t think you’ve got the hang of this science thing yet. Quantum mechanics is infernally complex and mind-numbingly counter-intuitive. It is the antithesis of “simple.” Yet it has no difficulty being considered as a sound piece of scientific understanding. That is because it fits the evidence. So where is Ockham’s razor in all this?
    Good old Wikithing says:-

    “In science, Occam’s Razor is used as a heuristic (discovery tool) to guide scientists in the development of theoretical models rather than as an arbiter between published models. In the scientific method, Occam’s Razor is not considered an irrefutable principle of logic or a scientific result; the preference for simplicity in the scientific method is based on the falsifiability criterion. For each accepted explanation of a phenomenon, there is always an infinite number of possible and more complex alternatives, because one can always burden failing explanations with ad hoc hypothesis to prevent them from being falsified; therefore, simpler theories are preferable to more complex ones because they are better testable and falsifiable.”

    But I always enjoy a good laugh. You say “The only explanation I’ve seen so far that satisfies Occam’s razor (w.r.t the ‘hiatus’) is falsification.” I have no idea what it is you are seeing as being falsified. I fail to grasp how a falsification process would be brought about within such a process. And I didn’t realise that Ockham’s razor could be “satisfied” by single explanations/theories/models. Indeed, I don’t even see how it can even be invoked in such ciscumstances.
    So do explain.

  25. 125

    OK, I just lost (to the vagaries of my browser) a lengthy and very carefully formatted comment on Victor’s #117 and the following responses from MA Rodger and Mal. Clearly, fate doesn’t want me to pontificate at length. (Cheers from the bleachers.)

    However, to summarize:

    1) Disagreement doesn’t a denialist make, IMO. Persistence in untenable lines of argumentation following adequate rebuttal, however, does.

    2) The Tollefson piece Victor links nicely describes the sort of “problem” that invites research. I’d agree that the hiatus is a ‘problem’ in the the sense of the term that a ‘research question’ is a ‘problem.’ (A trivial conclusion on my part, since there is rather a lot of research being devoted to it right now.) But a research problem does not necessarily a fundamental challenge to a well-estalished paradigm make. Tollefson spends most of the article describing research efforts to understand the hiatus which are being carried out under the established paradigm. Clearly, those scientists don’t feel that they are beating a dead horse.

    3) The assertion that some apparently are insisting “…that we should be willing to impoverish ourselves on the basis of unsubstantiated claims of imminent doom..” is one of the purer examples of straw man argument that I’ve seen lately. Just who is supposedly saying this?

    (Even the ‘simple life’ folks claim that life could be better if we recalibrated our values to put them in line with a lower-emissions lifestyle–and they are not a huge subgroup in this debate. Of course there are a few of the sort of doomers who insist things are hopeless, but not quite extinction-level hopeless. That would imply a severely impoverished future. But those folks aren’t advocating, they are warning–albeit, according to them, pointlessly warning.)

    It’s especially bizarre to link this supposed cadre of ‘impoverishers’ with Al Gore, who is nothing if not a techno-optimist–one who has always asserted that we have the technical and policy tools to do what we need to do, and that if only we summon the political will, everything will be quite rosy. (Perhaps the linkage was unintentional; Victor does use the term ‘pipe dream’ in connection with Mr. Gore. But the paragraph as written is, frankly, not very coherent.)

    One can certainly find strong counterexamples to Victor’s expressed view:

    Today, the data is clearer than ever and the New Climate Economy report, endorsed by a roll-call of the world’s major institutions including the World Bank, the OECD and the IMF, spells it out. If we want economic growth, we can have it – while reducing greenhouse gas emissions and building a new economy that brings a better quality of life for all, and most of all to those living in developing countries where the great majority of future population growth will be.

  26. 126
    Radge Havers says:


    “…the more explanations the better…”

    What are you talking about? The climate system has a lot of subtley moving parts. The less you understand how they fit together then more likely you are to make erroneous assumptions about, not only the system, but your ability to evaluate it (Dunning-Kruger) properly — leading to confused thinking like, for instance, misidentifying causality as in the fallacy of the single cause ( ) and fumbling with Occam’s razor.

  27. 127


    Good Lord, man! No, not all research is even aimed at solving the entirety of a given issue, so there is no obligation for every paper to, in your words, “demonstrate the necessity for offering only those reasons and no others.” Papers can legitimately suggest possible explanations for further investigation, present partial results, propose methods for investigation, or offer up the larger context (‘review articles’) without any need to address Occam.

    I get the impression mainstream climate scientists seem to think: the more explanations the better.

    Then your impression is sorely mistaken. If you really read the Tollefson piece you linked earlier, you should know that there is rather a lot of activity aimed precisely at elucidating which particular cause or causes is responsible for the hiatus, and to which degree. (Yes, *mainstream* research.)

  28. 128
    Steve Fish says:

    Re- Comment by Victor — 31 Oct 2014 @ 9:04 AM, ~#122

    Victor, there are not a bunch of theories to explain the, so called, hiatus. Scientists are testing hypotheses in order to work out why the relatively minor deviation of one metric of global warming (surface temperature) differs from model predictions. It will take a fair amount of research to work this problem out and it could turn out that there will be several, not mutually exclusive, factors. This is how models continue to improve.

    The fact that you don’t appear to understand this normal scientific research process, and that you don’t know the difference between hypothesis testing and theory, and that you don’t understand how inappropriate your application of Ockham’s razor is in this context, all suggest that you are not qualified to be interpreting science for others on your website. My criticism here is not an ad hominem fallacy.


  29. 129
    Hank Roberts says:

    As for my use of Climate Depot “as a source” — well, I didn’t … More defensiveness, I’m afraid.

    Victor, this is really boring. You say you’re an academic. Are you retired? Can you get to a science department library, biology or physics? If you go there, ask the reference librarian how to find good information, and read that, you’ll change your tune.

    If you are doing your research on the Internet, are you using Scholar? If not, you’ll be fooled by sites like Morano’s spin site, or the CO2Science spin site.

    They are very good at what they do.

    Yes, posting that chart from Morano is using it as a source for your claims, you’re relying on that as it’s been spun by Morano.

    The information available to you from RSS that accurately describes what the chart does and doesn’t tell us is there. Rely on that.

    Look, this isn’t just your problem. The methane emergency team does something very similar, showing charts of methane at 20,000′ elevation and claiming they’re showing methane coming from specific sites on the ground — even though the satellites are, in fact, being used to detect methane _at_ ground level.

    If you take a scientist’s work, spin it to make a political point, and put it out there, you’re deceiving people. Whether from right, left, or so far out to where they overlap on their tactics, it’s fooling people.

    You’ve found Morano’s spin site and fallen for his tricks, and you think you’re quoting science about the information.

    Please, look at the first link under Science Links — at the bottom of the right hand sidebar — that’s
    The Discovery of Global Warming – A History

    Don’t trust some guy on the Internet to give you a good link, type it into a search box.

    Read some history. Don’t be fooled again.

  30. 130
    Hank Roberts says:

    Victor, read the link re Ockham’s Broom.

    To elaborate that point briefly – While Ockham’s razor clearly has an established important and honourable place in the philosophy and practice of science, there is, despite its somewhat pejorative connotations, an honourable place for the broom as well. Biology, as many have pointed out, is untidy and accidental, and it is arguably unlikely that all the facts can be accounted for early in the investigation of any given biological phenomenon. … Clearly, though, it takes some special sophistication, or intuition, to judge what to ignore.

  31. 131
    Danny Thomas says:

    I perceive a scale, and look forward to others commentary.

    The “community” surrounding the topic of CC includes all types. Scientific to social to political.

    My perceived scale is CAGW to AGW to {GW GC(global cooling)} (a scale within a scale). Does anyone else see something similar and is there a “middle ground” that can lead to conversation and discussion without acrimony? I’m posing this question on others sites and am quite interested in others perceptions.

  32. 132
    Ray Ladbury says:

    Oh dear, Victor. You are so lost. Let’s think for a moment. We have a physical phenomenon–the recent “pause” in surface warming. We have several physical phenomena–e.g. ocean heat uptake, and so on that may be possible explanations. Care to tell me how investigating any of these potential contributors would violate “Occam’s Razor?” All Occam’s razor says is that if two theories perform equally well, we should take the simpler–in fact, for statistical models we can be more precise and use AIC or BIC to tell us which theory to take.

    Victor, please. You are playing the clown.

  33. 133

    My perceived scale is CAGW to AGW to {GW GC(global cooling)} (a scale within a scale). Does anyone else see something similar and is there a “middle ground” that can lead to conversation and discussion without acrimony?

    Danny, I perceive that one can construct such a ‘scale’ or spectrum. (After all, you did.) I’m not sure it’s that helpful a model, though. It would tend to suggest that there is some sort of symmetry and equivalency along the gamut that I don’t think is really there, either quantitatively (meaning, in terms of what proportion of the population share some particular view) or qualitatively (meaning, how well justified that view is in reality.)

    And I don’t like the formulation ‘CAGW’ much, for a couple of reasons. (For anyone who doesn’t already know–probably not too many on this site–that usually means “Catastrophic Anthropogenic Global Warming.”)

    First, it’s mostly used by denialists, who apparently think that it makes the mainstream sound less plausible. And second, “catastrophic” is itself, in this context, catastrophically under-defined. No one really has a clue what it means. For instance, my rough estimate is that climate change has to date killed in excess of a hundred thousand people, and cost in excess of a hundred thousand dollars damage. Is that ‘catastrophic’, as intended by the folks who use the tag CAGW?

    As to the issue of acrimony, I don’t think that there is any way of avoiding it. Some pairs of conversationalists may find common ground on the issue, but in the big picture this issue is acrimonious because important things are at stake, and so what people end up believing really matters. (Actually, that’s the thing the most polarized debaters of climate change share: the belief that the result of the debate is extremely important.) When power, money, and survival are at stake, people will fight.

  34. 134
    Victor says:

    First of all I want to thank all of you responding to my posts. I wanted a debate and I got one, so fine. I didn’t expect those hanging out here to respond positively to my negative take on global warming, so I’m willing to take the insults in stride. And yes, I have been learning from this exchange, so thanks again.

    I can’t respond to every single objection, but I’d like to focus some more on the Occam’s razor issue. Sure, global warming is a complex phenomenon. So is sea level rise. I recognize that. And if we want to fully understand it then we have to embrace complexity for sure. And yes, it is perfectly legitimate to consider and test all sorts of possibilities.

    However, that has nothing to do with the issue I raised. What we are discussing is not an abstract scientific question regarding the cause of global warming and sea rise, but an issue that has the world’s attention because what the world decides to do about it will have far reaching implications for literally everyone on the planet. And the focus of the issue is not the determination of all the different factors that can contribute to g.w. but the role of one particular factor: fossil fuel emissions.

    So what’s been on my mind in this entire discussion is: how do we determine that role? And at the heart of the debate is the question: does f.f.e. (fossil fuel emission) contribute significantly to g.w. and/or s.l.r. or not? And in order to determine this, one must leave aside all other factors for the moment and ask oneself two questions: 1. is there a correlation between f.f.e. and g.w. and/or s.l.r. or not?; and 2. given evidence of such a correlation, does the correlation reflect a causal relationship? Whether or not the sun is a factor or volcanoes are a factor or el nino or la nina are factors is beside the point. The issue at hand is the role of f.f.e.

    I’ve examined many graphs purporting to demonstrate a correlation, but I just don’t see it. Even according to the graph supplied by MA Rodger I don’t see it. From a certain point (roughly 1850), we see a steady rise in f.f.e., but when we look at warming we see several ups and downs, including at least one very dramatic downswing, from ca. 1940 to 1950 and of course the hiatus from ca. 1998 to present. What is more, we see a rise in ocean levels beginning long before the advent of the sort of heavy industry that produces high concentrations of f.f.e., which raises serious doubts regarding f.f.e. as a cause. And by the way, I’m talking specifically about f.f.e. NOT AGW in general.

    Now I understand what is being said here regarding the need to take additional factors into account, and sure, those factors must be taken into consideration. But here is the point where Occam’s razor comes into play. And I must insist this is more than simply a handy heuristic device to help us in our judgements. It is absolutely vital, as Heylighen explains. Also, it’s NOT just the question of what is the simplest explanation that fits the facts, it’s the problem posed by the “underdetermination of theories by evidence.”

    In order to establish a causal relation between f.f.e. and g.w., you have to at the very least establish a clear correlation between those two. NOT between and among all the different factors, but JUST THOSE TWO. And if there are anomalies, you need to do more than simply point to certain factors that might explain the discrepancy. Because there is a difference between explaining something and explaining it away. Ptolemy offered his epicycles, but never offered any reason why those epicycles were necessary. Kepler and Newton demonstrated that they weren’t and got rid of them. So if you want to say that, for example, ocean cooling or ocean warming account for the anomalies, you have to explain what makes that a necessary part of your argument. In other words, what makes it the simplest and thus most likely of all other possibilities? Otherwise, it becomes just another one of those infinite number of possible, but not convincing, theories cited by Heylighen.

    Now of course it’s a good idea to examine all possibilities and continue the research along many lines. But that’s not what we’re talking about here. Because as far as mainstream climate science is concerned, and to quote our beloved President: “the science is settled.” In other words what we are not hearing is that it looks as though f.f.e. is the cause of g.w. and s.l.r. but we can’t be sure because the science is just too complex. What we are hearing is that we know for sure what’s what and we need to do something about it NOW. So if you want to argue for complexity and how difficult it is to determine all the various causes, then you have no right to insist you know for sure what the truth really is, nor have you the right to lobby for dramatically curtailing fossil fuel consumption on that basis — especially given the serious hardships such a decision would entail.

  35. 135

    #134–OK. Victor, when considering correlation–and especially if you are going to ‘eyeball it’, which is a method of, shall we say, uneven reliability–it’s appropriate to consider the issue of time scale. As we discussed in connection with Santer et al, that’s very important. Over short time frames, the ‘other factors’ can have considerable influence over temperature trends. But CO2 (or CO2e) wins out over longer time frames in part because it tends to be more ‘inertial’–that is, it’s characteristic time scales of variability tend to be much longer.

    One of the clearest illustrations is the record in the Antarctic ice cores. Have a look at this graph and tell me what you think Occam’s has to say about it:

  36. 136
    MARodger says:

    I must be going blind. There’s lots of words @132 but can anybody point out to me the application of Ockham’s razor contained within that comment? Such application is apparently “absolutely vital” which means there are definitely lives at stake here, although I’m a little hazy about what lives. But it’s definitely a matter of life-or-death, apparently, so where is it?

  37. 137
    Radge Havers says:


    It kinda looks like you jumped into the deep end of the pool and started splashing everybody without bothering to familiarize yourself with even the basics of swimming. May be why people seem to be annoyed with you.

    The complexity of the natural systems and the science that explores them means that learning takes a lot of time and effort. Don’t confuse your lack of understanding with what others understand.

    CO2 and Warming
    “The effect of adding man-made CO2 is predicted in the theory of greenhouse gases. This theory was first proposed by Swedish scientist Svante Arrhenius in 1896, based on earlier work by Fourier and Tyndall. Many scientist have refined the theory in the last century. Nearly all have reached the same conclusion: if we increase the amount of greenhouse gases in the atmosphere, the Earth will warm up.”

    Humans and warming
    “Additional confirmation that rising CO2 levels are due to human activity comes from examining the ratio of carbon isotopes (eg ? carbon atoms with differing numbers of neutrons) found in the atmosphere. Carbon 12 has 6 neutrons, carbon 13 has 7 neutrons. Plants have a lower C13/C12 ratio than in the atmosphere. If rising atmospheric CO2 comes from fossil fuels, the C13/C12 should be falling. Indeed this is what is occurring (Ghosh 2003). The C13/C12 ratio correlates with the trend in global emissions.”

    Settled enough
    “That human CO2 is causing global warming is known with high certainty & confirmed by observations.”

  38. 138
    Radge Havers says:

    Sorry, that last link I posted should be:

  39. 139
    Mal Adapted says:

    Victor keeps digging himself a deeper hole. He’s convinced his amateur judgement on the complex topic of anthropogenc climate change is as good as the consensus of working, publishing climate scientists. His justification is:

    “I’m neither a climate scientist nor a physicist. But I am a student of the philosophy of science and I do think I know something about scientific method.”

    Victor is the paradigmatic victim of the Dunning-Kruger effect! The Wikipedia summary of the original paper by D&K is admirably concise:

    Dunning and Kruger proposed that, for a given skill, incompetent people will:

    fail to recognize their own lack of skill;
    fail to recognize genuine skill in others;
    fail to recognize the extremity of their inadequacy;

    How shall I count the ways? Victor thinks an acquaintance with “the” philosophy of science, and knowing “something” about scientific method gives him the skill to interpret the evidence he’s chosen to examine any way he chooses; he acknowledges he’s neither a climate scientist or a physicist, nevertheless he has no use for the hard-won consensus of actual experts; and when his errors of fact and logic are painstakingly explained to him, he doesn’t ask himself “Is it possible I’m not as good at this as I think I am?”, he complains about ad hominem attacks.

    (I was bemused by his response to my previous comment: “What you are actually saying is ‘I’m right and anyone who can’t see that is unqualified to express an opinion'”, as if I were claiming to be an expert myself. That’s something I’ve never claimed. I’m just literate enough in the natural sciences to recognize genuine skill when I see it, and meta-literate enough in the philosophy, culture and practice of Science to defer to the National Academy of Sciences, if not to the lopsided consensus of working climate scientists, when I’m out of my depth. Above all, I’m aware how easy it is to fool myself!)

    So why do we (well, I) keep responding to him? I suppose it’s because of Messrs. Kruger and Dunning’s additional proposition:

    …for a given skill, incompetent people will:

    recognize and acknowledge their own previous lack of skill, if they are exposed to training for that skill.

    I’m afraid I’ve lost hope of that by now, and I’m done with him.

  40. 140
    MartinJB says:

    Victor (134 – 31 Oct 2014 at 10:34 PM), I’ll give this one last try.

    This statement of yours is absolutely not true. The fact that you keep repeating it suggests a complete lack of understanding on your part about how science and quantitative analysis works: “In order to establish a causal relation between f.f.e. and g.w., you have to at the very least establish a clear correlation between those two. NOT between and among all the different factors, but JUST THOSE TWO.”

    Let me lay out the basic argument why this is wrong.

    1 – we know with remarkable certainty that CO2 is a greenhouse gas (established physics known for well over 100 years) and that burning fossil fuels increase the amount of CO2 in the atmosphere. Thus we have an incredibly solid causal relationship between fossil fuel use and increased heat content in the Earth system.
    2 – we know, again with a very high degree of certainty, that there are a lot of other factors that have an impact on both the heat in the system and the surface temperatures we’re most concerned with. These include but are not limited to solar cycles of various length, atmospheric aerosols that can reduce insolation, albedo and distribution of heat between the atmosphere in the ocean.
    3 – as a result of 2, over different time scales (and especially SHORT time scales) those other factors can swamp the impact of 1.

    Thus, it is absolutely not reasonable to always see (especially eyeballing graphs, as you seem to do) a “clear correlation” between “JUST THOSE TWO” factors (ffe and surface temperatures) as you insist. To say otherwise is utter nonsense. To “simplify” the question by excluding the other factors obfuscates the issue. It does not clarify it.

    What is perfectly reasonable is to use times of divergence from the underlying relationship to explore the impact of those other factors. I’d say that’s a big part of how science advances. If the way scientists explore those divergences deviates from some idealized expectation you have of how that should be done… well, maybe you need to explore your own preconceptions.

    Finally, while the “hiatus” is interesting, it is not unexpected. First, it is well within the range of the results produced by the simulations. Second, it has often been noted that periods without increased surface temperatures should be expected as a result of the noise (i.e. the other factors in the system). I believe Trenberth suggested one could have 30 years with little to no surface temp warming. See also Skeptical Science’s excellent “up the down escalator” graph.

  41. 141
    Ray Ladbury says:

    Victor, your arguments amount to nothing more than an argument from personal incredulity. This is a logical fallacy, and given the level of skill you’ve shown here and on your blog, I would strongly recommend reading the works of Dunning and Kruger before tackling the works of actual climate scientists.

    Did it ever occur to you that maybe people who have done this for a living for 30 years might have a slightly better understanding of the subject than you do? And when over 97% of them are in agreement, shouldn’t that tell you something?

  42. 142
    Meow says:

    @31 Oct 2014 at 10:31 AM:

    OK, I just lost (to the vagaries of my browser) a lengthy and very carefully formatted comment…

    Try using a text editor to edit comments, then copy them into the comment box.

  43. 143
    SecularAnimist says:

    Victor wrote: “In other words what we are not hearing is that it looks as though f.f.e. is the cause of g.w. and s.l.r. but we can’t be sure because the science is just too complex.”

    You are not hearing that from the scientific community, for the simple reason that it is not true.

    You are hearing it from the denialist websites that you have been citing for all of your spurious claims, because they exist to deceive you.

    Victor wrote: “What we are hearing is that we know for sure what’s what and we need to do something about it NOW.”

    Yes, you are hearing that — indeed you have been hearing that for decades — from thousands of climate scientists from all over the world, from every national scientific academy of every nation on Earth, and from every international scientific organization in the world that has anything to do with climatology.

    You are not, of course, hearing it from the denialist websites you have been citing, because they exist to perpetuate business-as-usual consumption of fossil fuels for as long as possible.

  44. 144
    Danny Thomas says:


    Thanks for your response. I’m bringing up the thought process of a “scale” with no disrespect intended on the CAGW label. As I’m new here and first time poster. I’m seeking an education. Unfortunately I’m not a scientist, but so much of the conversation is political my perception is that cutting through is a challenge. The thought of the scale is to get an understanding of where the ends are as well as the middle. I can’t help but disagree that this doesn’t have to be a fight, but should be a data, evidence, fact based conversation. But that’s so very hard to find.

    I’m on several sites, Judith Curry, Watt, here as I’m kinda the outlier of the Pew survey as I seek differing views.

    I found this to be an interesting thought process:”

    Not my words, but from above:
    “I give you this:

    Put a conservative in a room with a poll and ask him whether he supports cleaner air. Why of course he does! More efficient energy use? Sure! More solar energy? Yes, please! People like cleaner, more, and better, generally speaking.

    Now imagine that conservative in his living room, watching Fox or listening to talk radio. Is he hearing about cleaner air? No, he’s hearing about job-killing regulations, which he hates. Is he hearing about efficiency savings? No, he’s hearing about Big Government coming to take his lightbulbs, and he hates that. Is he hearing about the recent flourishing of solar power? No, he’s hearing about Solyndra, about government boondoggles and giveaways. He hates those.”

    I have a CAGW buddy who’s views I’m not comfortable with. The CAGW term originated in my vocabulary from him. Since I’m not one to just accept what I hear I have to research for myself. This is what leads me here and the other sites.

    Looking forward to the education.

  45. 145
    Hank Roberts says:

    For Victor:

    That’s news; it is not the last word.

    There is no last word, except hindsight.

    That’s the definition of climate sensitivity: the change after a single event, once everything has settled down. Estimates are made; that’s the best we can do in advance.

    > debate
    No, you didn’t get a debate. You used debate tactics in a conversation about science. It’s kind of like, what’s the idiom I want here, hmmmm ….

  46. 146
    Steve Fish says:

    Re- Comment by Danny Thomas — 1 Nov 2014 @ 2:25 PM, ~#144

    Hi. One of the standard recommendations here is to read Spencer Weart’s “Discovery of Global Warming.” I did this almost 10 years ago when I first started visiting here. It is free. At the top of the main page under “Start here” (left side) scroll down to “Informed, but in need of more detail” to find a hyperlinked text. The historical view is fascinating.


  47. 147
    Radge Havers says:


    The realty of global warming is a scientific issue not a political one. From that perspective, there is one reality that rules: Mother Nature’s. Views of it are either closer to reality or farther away from it. Splitting the difference between views only puts you farther away than the best available model. So the applicable spectrum here is between accurate and inaccurate.

    What to do about it is at least in part a political issue, however. In terms of policy applications, you may have to split the difference. But that only works if significant stakeholders are sharp enough to recognize the problem in the first place (i.e., are not wearing stupifying ideological blinders).

  48. 148
    Hank Roberts says:

    For Danny Thomas:
    Bridging the Chasm between Two Cultures

    It is not merely, as many surmise, a conflict between fact-based viewpoints and faith-based viewpoints. Nor is it simply a conflict between rationality and credulity. No, it’s a full-on clash of cultures that makes real communication improbable at best.

  49. 149
    Danny Thomas says:


    Thanks! I’ll go look for that.

  50. 150
    Victor says:

    My oh my. Where to begin? OK, first things first: climate scientists genuinely concerned about the future of the planet can’t just talk among themselves, preaching endlessly to the choir. They need to be able to communicate with non-scientists, since the vast majority of those who make policy all over the world are not climate scientists.

    However, they are, for the most part, not stupid. Regardless of how many of you agree regarding “the science,” if you can’t formulate your arguments in a manner that makes sense to non-climatologists your recommended policies will not be adopted. And by the way, you shouldn’t be fooled by all the lip service you’ve been getting lately from the media. There’s little likelihood the extreme measures being urged by so many climatologists will be adopted. Not that you haven’t scared the bejeezus out of everyone, but because most people are not going to vote themselves into poverty over an issue they don’t understand.

    They won’t challenge you, as I have. But they won’t go along with your advice either.

    And by the way, as far as Mssrs. Dunnnig and Kruger are concerned, a great many scientists, not only ideologues, share views similar to mine and are raising similar questions. Some are at “denier” sites, many are not. Unless, of course, anyone who challenges the orthodoxy is by definition a “denier.”