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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…

References

  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. http://dx.doi.org/10.1007/s00382-014-2342-y
  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. http://dx.doi.org/10.1038/ngeo1836
  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. http://dx.doi.org/10.1002/qj.2297
  4. D.T. Shindell, "Inhomogeneous forcing and transient climate sensitivity", Nature Climate Change, vol. 4, pp. 274-277, 2014. http://dx.doi.org/10.1038/nclimate2136
  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. http://dx.doi.org/10.1038/nclimate2389
  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. http://dx.doi.org/10.1038/nclimate2077

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

  1. 201
    Victor says:

    #198 Marcus

    It was pointed out that two of the graphs I presented, taking us back to 1880 and 1870, were misleading because they didn’t take us back far enough in time. I was presented with another graph taking us back to 1700, and in the light of that graph I was forced to admit that I’d been basing my thinking on incomplete data. Which I did. I inserted the new graph into my post and discussed it. You can see it here:
    http://1.bp.blogspot.com/-jYN7Dtgg2Ts/VEFYykTCglI/AAAAAAAAA5c/J-afgk_09vM/s1600/Sea%2BLevel%2Bvs%2Btemperature%2B1700-2000.jpg

    However, this didn’t resolve the problem, because even on this more complete representation of the data, the sea level rise (in blue) begins around 1795, preceding the temperature rise, which begins around 1810. It’s hard to believe either rise could have been precipitated by fossil fuel emissions at such early dates. According to another graph, from the Carbon Dioxide Information Analysis Center, global fossil fuel CO2 emissions weren’t much of a factor prior to 1850: http://cdiac.ornl.gov/trends/emis/graphics/global_ff_1751_2006.jpg

    I’m not sure why such comments regarding very obvious features of these graphs are getting everyone so worked up. They seem pretty straightforward to me. If I’m ignoring the evidence then by all means show me what it is I’m ignoring.

  2. 202
    MARodger says:

    I think I rather regret being, as Victor the Troll put it @183, the “someone [who] sent me[Victor] a link to the following paper” ie Shakun et al (2012). I sarcastically suggested @159 that this paper would be useful ‘light reading’ for him. Now he accuses the authors of “confirmation bias” which is a dreadful accusation to make. The only mitigating circumstance is that Victor the Troll is a total idiot and probably doesn’t appreciate what he is saying.
    Victor the Troll’s critique of the paper, such as he provides, is in truth vaccuous and wrong, and bear in mind he says @183 “I’m not going to attempt an analysis or critique of their model per se because I’m clearly not qualified to do that. For all I know it could be correct.” It is difficult to countenance that the paper presents findings based on any particular “model” in the narrow sense of the word, so the Troll is really just showing he is entirely out of his depth.
    Indeed, Victor the Troll likely failed to even attempt to read the paper, probably confining himself to a quick scan of the Abstract. And even in carrying out that simple task Victor failed to note that this short account does find time to state within framing the research “The role and relative importance of CO2 in producing these climate changes [ie ice age deglaciations] remains unclear.”
    The first paragraph of the paper (not far to read) explains further:-

    The ice-core record now extends back 800,000 yr and shows that local Antarctic temperature was strongly correlated with and seems to have slightly led changes in CO2 concentration. The implication of this relationship for understanding the role of CO2 in glacial cycles, however, remains unclear. For instance, proxy data have variously been interpreted to suggest that CO2 was the primary driver of the ice ages, a more modest feedback on warming or, perhaps, largely a consequence rather than cause of past climate change.

    And five lines into the second page we read

    “Thus, the small apparent lead of Antarctic temperature over CO2 in the ice-core records does not apply to global temperature,”

    followed by further broad discussion of this finding.
    Thus to write of Shakun et al (2012) regarding the lead of ∆T(Antarctic) preceeding ∆CO2 within ice cores that “they neglect to mention that it’s a problem at all” and “they simply ignore the problematic nature of the evidence” is obviously wrong and given the Troll concludes from this obvious error that the paper is the product of “confirmation bias”, it is also libellous. Sadly such a level of egregious comment, surely inapproporiate at RealClimate outside the borehole, has become par for the course for our Victor the Troll.

  3. 203

    #196, Victor–Your ignorance of the literature is betraying you in this comment. There was no reason for Shakun et al to be surprised that CO2 rise lagged temperature, because that had been known (more or less) since 2001, and suspected for ten years before that:

    Second, the idea that there might be a lag of CO2 concentrations behind temperature change (during glacial-interglacial climate changes) is hardly new to the climate science community. Indeed, Claude Lorius, Jim Hansen and others essentially predicted this finding fully 17 years ago, in a landmark paper that addressed the cause of temperature change observed in Antarctic ice core records, well before the data showed that CO2 might lag temperature. In that paper (Lorius et al., 1990), they say that:

    …changes in the CO2 and CH4 content have played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing…

    See more at: http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/?wpmp_tp=1#sthash.AsDOLbn7.dpuf

    (Note that the RC post in question is from 2007, five years before Shakun et al.)

  4. 204
    Danny Thomas says:

    #189 Kevin
    #193 Radge
    #197 MARodger

    Thank you for your responses. I will read, and will move over to the open thread. I was sent a link to this thread so I assumed it was the “door”. My apologies to all.

    Danny

  5. 205
    Victor says:

    #203 Kevin, thanks for the link to that RealClimate post by Eric. In this case, the author clearly acknowledges the problem, though he sees it more as a problem of perception rather than a challenge presented by the evidence. I appreciate his frankness, and the relatively non-technical nature of his explanation, but as the explanation continues, it becomes clear that a very heavy load of complexity is being grafted onto what is usually presented as a very simple claim: CO2 emissions produce global warming.

    Now forgive me if I return at this point to Occam: “Entities should not be multiplied unnecessarily.” This does NOT imply that the simplest explanation is to be preferred, but that the simplest explanation found to be necessary, i.e., fully consistent with the evidence, should be preferred.

    Eric writes at one point: “While we don’t know precisely why the CO2 changes occur on long timescales, . . . we do know that explaining the magnitude of global temperature change requires including CO2.” In my opinion, this statement is the key point of the whole argument, because it makes a claim bearing on necessity. In other words, all the added complexity can be defended if its necessity can be established, i.e., if it can be demonstrated that the evidence makes no sense otherwise. It’s not clear to me that it HAS been established, but if it in fact has, then it satisfies the requirement of Occam’s razor. One of several reasons why I find this particular explanation far more satisfying than most I’ve seen.

    The graph Eric presents is similar to the one we’ve already seen. I’m assuming this is a representation of the data referred to in the Shakun paper (please correct me if I’m wrong). If it is, then once again I’m puzzled, since I see no evidence of feedback, but simply a recurring cycle. Also, if CO2 and temperature alternately took the lead, then the alternation should be reflected in the data, but that isn’t evident from the graph.

    While I very much appreciate Eric’s explanation, I’m still left with doubts because of the inordinate amount of complexity necessary to establish CO2 as a driving force in warming when so much of the raw date implies otherwise. It’s not difficult to understand how deniers could see this complexity as a fudge.

  6. 206
    marcus says:

    #201 Victor, you do not have the impression that it needs a little reading and learning the science befor eyeballing such graphs and drawing bold conclusions about correlations, do you?
    There is simply no not the slightest feature here to be interpretet as that sea level rise preceeded global warming (for your CO2 graph keep in mind, that the radiative forcing goes roughly with log(pCO2), by the way).
    You are expressing confusion about some minor dip around 1710 instead, stipulate some peak in sea level having the exact shape (what is utterly naive, except for the irony that such a peak is there with some delay), and still chose to stick to the “cart before horse” nonsense, because what shalt not be true can’t be true.
    You seem to be more willing to exhaust what you actually *want* to vbeleoive, than to dig into the subject and grow with it, and be sceptical to your own reasoning. Not much fun, in my opinion

    Cheers

  7. 207
    MARodger says:

    marcus @198.
    Do ignore Victor the Troll @201 when he says “If I’m ignoring the evidence then by all means show me what it is I’m ignoring.” Showing him simply allows him to ignore it some more. He should know already what he is ignoring. He has been shown enough times.
    Since his comment @104 Victor the Troll has pursued what he feels is a clever way of presenting his case by declaring that it is all about CO2 emissions from fossil fuels and nothing else. (Before #104 he contradicts such a view on numerous occasions.) So if there is any data showing a change in global temperature or SLR that does not waggle in unison to FF CO2 emissions (and it would be surprising if there wasn’t), then in Victor’s limited understanding AGW is thus disproved. That is the depth of argument Victor allows himself.
    Interestingly, the deficiencies in such an argument was part-enumerated just up-thread @197. As of 2011, CO2 represented but 53% of the positive AGW forcings (according to IPCC AR5 Table AII.2). Added to that, the figure would fall to 35% if just FF CO2 emissions were considered.

  8. 208
    Radge Havers says:

    Shorter Victor:
    “If it’s too complicated for me to put together, then it’s too complicated to be real. I have declared it so.”

    I would suggest at this point that since Victor is dodging the bore hole, his OT and loquacious laziness should be addressed on the Unforced Variations thread if not ignored altogether. MARodger is probably correct, BTW, insofar as he’s stopped talking to Victor directly and is instead discussing those issues with more serious commenters.

  9. 209
    Ray Ladbury says:

    So, is “Victor” a bot? Certainly, it hasn’t passed the Turing test. I’ve seen no evidence of a positive slope in its learning curve.

  10. 210
    Victor says:

    #206 Marcus

    “You are expressing confusion about some minor dip around 1710 instead, stipulate some peak in sea level having the exact shape (what is utterly naive, except for the irony that such a peak is there with some delay), and still chose to stick to the “cart before horse” nonsense, because what shalt not be true can’t be true.”

    The above is not a sentence in the English language. I have no idea what you’re trying to get across.

    Be that as it may, I’m getting really tired of people reminding me I need to read more and learn more about the science. That’s what I’ve been doing. And I’ve been reporting on what I’ve read and how I understand it. But no matter how much I read in this literature that will not make me a climate scientist, obviously, so please don’t act as though you expect me to become one.

    If climate scientists want to change the way we do things in this world they need to be able to communicate with non-scientists, not brow beat them into submission.

  11. 211
    Steve Fish says:

    Come on guys; lighten up a little on Victor. Whether he doesn’t have the mental horsepower to understand a little complexity or is just exercising a trolling hobby, I can say, without reservation, that he is an excellent, and I mean a very top ranking bad example.

    Steve

  12. 212
    Hank Roberts says:

    Shorter:
    blah blah blah blah Victor blah blah blah blah

    Give him what he wants, maybe he’ll go away. He’s not here to read.

  13. 213
    Meow says:

    Just a two quick questions to all here who claim they’ve “falsified AGW”.

    1. Please concisely state the theory that you think you’ve falsified.

    2. Please tell us why earth’s global average surface temperature is ~288 K instead of ~255 K., given the solar flux at earth’s orbit of ~1366 W/m^2 and earth’s albedo of ~0.3. Cite only established physical principles.

  14. 214
    Ray Ladbury says:

    Victor, Given your fetish for simplicity, I am surprised that you haven’t mentioned Foster and Rahmstorf 2011. After all, models (at least useful ones) don’t get a whole lot simpler than the one used there. What say you to a paper that shows that if you correct or ENSO, volcanism and insolation, you get the same warming trend for all the major temperature indices for over 30 years. We know all of these variables are acting and are important–that seems to be a pretty damned strong argument that anthropogenic warming is needed to explain the data over the past several decades.

  15. 215
    Meow says:

    I’d like to ask two quick questions of all claiming to have “falsified AGW”.

    1. Please concisely state the theory that you assert you’ve falsified.

    2. Please tell us why earth’s global average surface temperature is ~288 K instead of ~255 K, given the solar flux at earth’s orbit of ~1366 W/m^2 and earth’s albedo of ~0.3. Cite only established physical principles.

    ..

  16. 216

    #205–“If it is, then once again I’m puzzled, since I see no evidence of feedback, but simply a recurring cycle. Also, if CO2 and temperature alternately took the lead, then the alternation should be reflected in the data, but that isn’t evident from the graph.”

    – See more at: http://www.realclimate.org/index.php/archives/2014/10/climate-response-estimates-from-lewis-curry/comment-page-5/#comment-617118

    Of course it isn’t. A graph that covers hundreds of thousands of years isn’t going to resolve 800 years.

  17. 217

    “…inordinate amount of complexity necessary to establish CO2 as a driving force in warming…”

    – See more at: http://www.realclimate.org/index.php/archives/2014/10/climate-response-estimates-from-lewis-curry/comment-page-5/#comment-617148

    Allow me to simplify for you: no other candidate explanation for the warming seen in recent decades–and the search for such *in general* (not, obviously in “recent decades”) has been on for nearly 200 years now–has survived the scientific winnowing that has been going on in earnest for nearly as long.

    The explanation we have may be complicated, but there is not, at present, a simpler one that actually works, though there are number of failed candidates: it ain’t the sun; it ain’t cosmic rays; and from energetic considerations(despite dogged efforts by penny-wise/pound-foolish types) it ain’t (I am pretty certain) going to be natural variability–not even if it gets cute names like ‘stadium waves.’

    At present, this is the closest shave Occam is going to get. And the ‘present’ has been going on for a while now, so to speak.

  18. 218
    marcus says:

    #207 MARodger

    Appeared to me like a genuine skeptic at first sight, but on second… well, enough time wasted.
    Put that to a test with this “cart before horse” assertion: seeing the material he has been provided with that had to go off his blog, there is not the slightest excuse, and would not be the slightest problem for a *real* skeptical person.
    For me, first hand this sounded interesting: could it be that sea level rise really predates industrial CO2 rise, what do we know about it, are there sources and how reliable are they?
    The skeptoc starts looking up things, reads, compares and understands. The pseudoskeptic keeps babbling on

    Cheers

  19. 219
    Hank Roberts says:

    > communicate with non-scientists, not brow beat them into submission.

    This requires a brow high enough to …. oh, wait, I’m taking the bait.

    Nevermind.

  20. 220
    Phil Scadden says:

    #215 Meow – I really like that. I will use it.

  21. 221
    Victor says:

    #214 Ray Ladbury

    Yes, I read the Rahmstorff and Foster paper a week or so ago after a referral from someone commenting on my blog. I’m glad you brought that up because it’s a perfect example of why I feel so confident challenging climate scientists over this issue.

    From R and F’s conclusions (http://iopscience.iop.org/1748-9326/6/4/044022/pdf/1748-9326_6_4_044022.pdf):

    “The resultant adjusted data show clearly, both visually and when subjected to statistical analysis, that the rate of global warming due to other factors (most likely these are exclusively anthropogenic) has been remarkably steady during the 32 years from 1979 through 2010.”

    In evaluating models of this sort it’s important to keep in mind the formula I keep quoting: “the underdetermination of theories by data.” As Heylighen explains, “For a given set of observations or data, there is always an infinite number of possible models explaining those same data.”

    To get around this problem it’s not enough to construct a model that fits the data. It should be, first of all, the simplest model that fits the data.

    But their model is far from simple, as it requires the addition (or rather subtraction) of three different elements to the original dataset. Moreover the model fits the data retroactively, which makes it even more questionable.

    Models of this sort are all too easily constructed. What I imagine they did was to start with ENSO, test it, realize it wasn’t enough. So back to the drawing board, trying out this that and other, tweaking the data from time to time (or as they put it “adjusting” it), until they find another likely candidate: volcanic aerosols. So add that to the mix. Well, that’s not good enough either so let’s try some more. Lo and behold solar activity does it. Now they have a graph that looks “just right.”

    I don’t doubt they know what they’re doing from a technical and mathematical standpoint, and I’m sure they feel confident they’ve found the right mix of inputs to demonstrate that such inputs most likely explain the hiatus. And maybe those inputs do in fact explain it. However: a model that “predicts” only retroactively doesn’t really cut it.

    My suggestion: let’s wait another two or three years and then see how their model looks. Fair enough?

    One more thought out of season: the period when everyone got really concerned about global warming, and began insisting we act NOW to fix it, was the period between 1979 and 1998. That’s the period of the hockey stick, right? When it looked like global warming was soaring out of control due to that sharp rise in CO2 emissions. That was a period of only 19 years. And we are now fast approaching 19 years in which we no longer see anything like that earlier strong correlation. So why is it that the latter stretch is due to normal climatic variation but the earlier one can’t also be?

    In other words, why is it that the latter stretch but not the earlier one is what needs to be explained?

  22. 222
    Hank Roberts says:

    > My suggestion: let’s wait another two or three years and then
    > see how their model looks. Fair enough?

    Innumerate.

    Statistics 101 isn’t required for a liberal arts degree.
    Pity, that.

  23. 223
    MARodger says:

    So @196 we have had Victor the Troll accusing Shakun et al (2012) of “confirmation bias”. Then @205 we have him mis-reading a post by one of our hosts. That is, the Troll ignores the statement “…the direct radiative effects of CO2 on climate have been known for more than 100 years,” on which Eric Steig sets his argument.
    It should be clear to all (except one) that Victor the Troll is not reading these papers that people kindly (or otherwise) point him at. Instead he is mining them for cherry-picked phrases that suit his own purpose.
    And now @221 the Troll is accusing another one of our hosts of curve-fitting. (Is it possible he swaps the author list around on purpose?) Given the vast number of inflection points within ENSO, volcanic (See for instance, two clicks down here) & solar forcings over the 1979-2010 period, it is an accusation of curve-fitting is eye-popping stupidity. Perhaps it is more forgivable to point out that the wait of “another two or three years” has occurred since 2010, it now being AD2014. And (here and here is the latest version to hand) “their model looks” exactly as it did up to 2010.

    When we see the village idiot approaching, many will act to avoid getting embroiled in his lunacies. Life is too short. RealClimate is meant to be a place for scientific discussion and is surely not the place for Victor the Troll (who is actually too stupid to be a troll without help). The post @221 outwardly poses two answerable questions but Victor the Troll will fail entirely to engage with any answers he is offered. He is in denial having convinced himself that CO2 is not an agent of climate forcing. The borehole would be more appropriate for such a one.

  24. 224
    MARodger says:

    Victor the Troll @221. Go on! Prove me wrong. For once engage with what other people are saying here.
    It is not as you suggest “fair enough.” The curve-fitting accusation is fatuous give the wobbles of ENSO and volcanic eruption are visibly evident in the global temperature record and so also is the solar impact when subject ot statistical analysis. And with the data since 2010 continuing to show the same result, your ‘wait & see’ has already been & gone.
    As for your suggestion that since 1998 global warming has not been “soaring out of control,” why then is it that the rise in global average temperature continued to accelerate 1998-2007, as demonstrated here (usually 2 clicks to ‘download your attachment’) by the red trace?

  25. 225
    Ray Ladbury says:

    Victor,

    Got it. [edit – try to restrain yourself]

    So, let me get this straight: Any phenomenon that requires 3 or more parameters to understand must be bogus? So, I presume you’ll be writing a post rejecting geometry next, since you need 3 dimensions to understand that. And thermodynamics–ferchrissake, you need temperature, volume and pressure to investigate gasses. Forget that.

    So, Victor, since 3 influences is too much, how many is the right number? Shall we ignore solar radiation? How about volcanic aerosols? El Nino?

    Victor, there are some phenomena out there that are inherently complicated. They require consideration of many, many variables for understanding. Complexity doesn’t scare real scientists. They know how to deal with it. You, on the other hand, are a joke. And what is even sadder, you’re the only one who doesn’t get the joke.

  26. 226

    #221–

    In other words, why is it that the latter stretch but not the earlier one is what needs to be explained?

    – See more at: http://www.realclimate.org/index.php/archives/2014/10/climate-response-estimates-from-lewis-curry/comment-page-5/#comment-617252

    Because that is the one that ‘skeptics’ insist ‘falsifies’ GW. If you look at modeling studies, actual researchers typically have considered the long term, say the whole 20th century, when assessing model skill.

  27. 227
    Meow says:

    A few questions to those who claim that “the hiatus” has “falsified AGW”:

    1. Why do you choose 1998 as the year from which the temperature trend to the present should be measured?
    2. What happens to the trend if you choose 1997, 1996, 1995… or 1999, 2000, 2001… instead?
    3. What does the answer to (2) tell you about the choice of 1998 as the beginning of the measurement period?
    4. What happened in 1998?
    5. Why is the answer to (4) relevant to the selection of that year as the beginning of the measurement period?

  28. 228
    Victor says:

    [edit – leave it out]

    Your refusal to accept clear explanations of very basic principles, such as “the under-determination of theories by data,” as though they could easily be ignored, only reinforces my skepticism of the “science” you claim to represent. But that’s not the only principle you conveniently ignore. And this really shocks me. You have no problem accepting a model based on evidence culled from the past yet refuse to acknowledge any need to test it based on evidence emerging from the present and future. It’s not difficult to cherry pick (yes, that’s the word for it, sorry) retroactively to come up with a graph that “fits” — it’s far more difficult to come up with a theory that can be tested, and pass the tests. You see no need for testing, which is truly scandalous.

    #223 MARodger

    “Perhaps it is more forgivable to point out that the wait of “another two or three years” has occurred since 2010, it now being AD2014. And (here and here is the latest version to hand) “their model looks” exactly as it did up to 2010.”

    Laughable. Take another look at your second graph: http://www.realclimate.org/images/adj5.jpg

    The trend peaks at 2010 — and sharply descends from there. No one knows whether it’s going to continue descending or rebound upward. Yes, on the surface it LOOKS like a confirmation because at the moment the descent fits the pattern, but who knows how it will continue. Clearly it’s too soon to adequately test the model. We will just have to wait and see.

    #225 Ray Ladbury

    “So, let me get this straight: Any phenomenon that requires 3 or more parameters to understand must be bogus?”

    Is that really your take on Occam’s razor? My oh my! You can have a thousand parameters so long as you can establish the necessity of each and every one in accounting for the evidence. Ptolemy could get his epicycles to fit the evidence but he was never able to explain why his approach was superior to that of anyone else who came up with a different scheme that also fit. It was only until Newton came along that the real solution was found, and it was convincing not only because it was simpler but because he could invoke the insights of Copernicus and Kepler, as well as the principle of universal gravitation, to demonstrate its necessity. It was also more predictive, because it didn’t require a continual adjustment of the parameters as time went on, which Ptolemy and his followers needed to do. And which climate scientists are doing today.

    #227 Meow

    I’m not the one who came up with 1998, that’s a year I see all over the place in the literature as the presumed starting point for the hiatus. If you’d rather pick some other year, be my guest. The overall picture won’t change.

  29. 229

    #227–Just so.

    Questions are often better pedagogically than answers. Hopefully some will take those questions and seek out answers for themselves.

    Hint for answering #2: a convenient tool for calculating this is found at woodfortrees.

    For example:

    http://www.woodfortrees.org/plot/rss/from:1999.1/plot/rss/from:1999.1/trend

  30. 230

    Victor–

    I’m not the one who came up with 1998, that’s a year I see all over the place in the literature as the presumed starting point for the hiatus. If you’d rather pick some other year, be my guest. The overall picture won’t change.

    Actually, it will change, and quite drastically. That’s part of what makes it a cherry-pick–it is ‘not robust.’

    Take Meow’s questions seriously–you are brushing them off, which is not what a skeptic is supposed to do. Try running trend analyses from those years and see for yourself what happens. I’ve pointed you to a site that not only makes it easy, it makes it almost fun.

  31. 231
    Radge Havers says:

    dftt

    I suspect that this is either a familiar troll who is known to go by various aliases (and sock-puppets) or is a reasonable facsimile thereof.

    The method of constructing strawmen out of slight misreadings and pseudo-logic can and will be used perpetually. It is juvenile mockery designed to make you run around in frustrated circles. Don’t waste your time.

  32. 232
    Steve Fish says:

    Come on everybody. I realize that Victor has a certain amusement value, but if we continue to respond to his unscientific nonsense we just become his pretty playpen toys. It is time to give up.

    Steve

  33. 233
    Hank Roberts says:

    Yeah, I’d guess that Victor has been here before under some other name,
    channeling the same stuff — Morano, CO2Science, and so on.

  34. 234
    Victor says:

    Glad to learn I’ve amused some of you. You guys have amused me no end. But it will stop being amusing when the victims of the insane policies you advocate catch on to the nature of the game you’re playing. You distract from all the really compelling issues of the day, such as the economic crisis, the takeover of democracy by the oligarchs, the mass unemployment and underemployment, the exploitation of the working class, the debilitating inequality, the possibilities of nuclear war and/or nuclear meltdown, to focus on a threat that will either never materialize at all, or, in the unlikely event it does, be all but unavoidable — according to your own calculations.

    There’s no point in wasting my time “trolling” this blog anymore. You people are impervious to logic. It’s been fun, I’ll say that. I love kids, even when they’re being nasty. So. How’s about a big hug before I go????

  35. 235
    Meow says:

    A few more questions for those claiming to be “skeptics”:

    1. You go to Vegas to play a common game with a ball and spinning wheel that cannot directly be mentioned here. You play the simplest strategy, betting each spin on whether a single number will come up. You always bet $5. On your first spin, your number comes up and you win $180, but you lose the next 40 spins.

    a. Your friend Andrew says that the house is cheating and offers to call the g*mbl*ng regulator. Do you take his offer? Why or why not?
    b. Your friend Betty says Andrew is full of it because 40 spins is far too few to decide. Do you agree? Why or why not?

    2. Your friend Toby, who lives in the hills, says he’s invented a fantastic automotive mileage enhancer, and he urges you to invest in it, promising stellar returns. You’re skeptical, and ask for a demo. So you drive to his house, and he fills up his car at a nearby station, then drives it to your house, fills it up again, and calculates the mileage. Voila! 70 mpg! And from a land-yacht of a 1974 Impala, too.

    a. Do you invest in his invention? Why or why not?

  36. 236

    #234, Victor–

    But it will stop being amusing when the victims of the insane policies you advocate catch on to the nature of the game you’re playing. You distract from all the really compelling issues of the day…

    This bluster would be much more impressive had you ever actually responded to my repeated requests to justify your ‘economic alarmism.’ But, unless I’m missing something, you have offered not one word of evidence to support your extreme statements–and that’s rather in contradistinction to what I have offered, which includes several very substantial reports on the issue.

    You also say that other commenters here are ‘immune to logic.’ You, however, seem to be immune to evidence.

    If you are really done with your click-bait trolling (which I by no means take for granted), I for one will cry no tears.

  37. 237
    MARodger says:

    Kevin McKinney @236.
    I think you will find that both the ‘immunity to logic and also the ‘‘immunity to evidence’ was overwhelmingly collected within statements which had just the one origin in the above thread. Interestingly, in a thesis addressing of that subject so often mentioned by the dear departed, “The Underdetermination of Theories by Data,” the author Newton-Smith develops two responses (modified forms) to the “realist’s dilemmma.” These responses Newton-Smith names as the Ignorant and the Arrogant Responses, noting that “the two modified forms of realism while quite different have much in common.” Having experienced the argumentation presented down this thread by our dear departed, I feel Newton-Smith was spot on with his naming of these responses but also I wonder if the two of them can be entirely “quite different” after all.