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CO2 lags temperature - what does it mean?

What the science says...

Select a level... Basic Intermediate Advanced

CO2 didn't initiate warming from past ice ages but it did amplify the warming.  In fact, about 90% of the global warming followed the CO2 increase.

Climate Myth...

CO2 lags temperature

"An article in Science magazine illustrated that a rise in carbon dioxide did not precede a rise in temperatures, but actually lagged behind temperature rises by 200 to 1000 years.  A rise in carbon dioxide levels could not have caused a rise in temperature if it followed the temperature." (Joe Barton, US House of Representatives (Texas) 1985-2019) - Full Statement

Earth’s climate has varied widely over its history, from ice ages characterised by large ice sheets covering many land areas, to warm periods with no ice at the poles. Several factors have affected past climate change, including solar variability, volcanic activity and changes in the composition of the atmosphere. Data from Antarctic ice cores reveals an interesting story for the past 400,000 years. During this period, CO2 and temperatures are closely correlated, which means they rise and fall together. However, based on Antarctic ice core data, changes in CO2 follow changes in temperatures by about 600 to 1000 years, as illustrated in Figure 1 below. This has led some to conclude that CO2 simply cannot be responsible for current global warming.

Figure 1: Vostok ice core records for carbon dioxide concentration and temperature change.

This statement does not tell the whole story. The initial changes in temperature during this period are explained by changes in the Earth’s orbit around the sun, which affects the amount of seasonal sunlight reaching the Earth’s surface. In the case of warming, the lag between temperature and CO2 is explained as follows: as ocean temperatures rise, oceans release CO2 into the atmosphere. In turn, this release amplifies the warming trend, leading to yet more CO2 being released. In other words, increasing CO2 levels become both the cause and effect of further warming. This positive feedback is necessary to trigger the shifts between glacials and interglacials as the effect of orbital changes is too weak to cause such variation. Additional positive feedbacks which play an important role in this process include other greenhouse gases, and changes in ice sheet cover and vegetation patterns.

A 2012 study by Shakun et al. looked at temperature changes 20,000 years ago (the last glacial-interglacial transition) from around the world and added more detail to our understanding of the CO2-temperature change relationship.  They found that:

  • The Earth's orbital cycles triggered warming in the Arctic approximately 19,000 years ago, causing large amounts of ice to melt, flooding the oceans with fresh water. 
  • This influx of fresh water then disrupted ocean current circulation, in turn causing a seesawing of heat between the hemispheres.
  • The Southern Hemisphere and its oceans warmed first, starting about 18,000 years ago.  As the Southern Ocean warms, the solubility of CO2 in water falls.  This causes the oceans to give up more CO2, releasing it into the atmosphere.

While the orbital cycles triggered the initial warming, overall, more than 90% of the glacial-interglacial warming occurred after that atmospheric CO2 increase (Figure 2).

Shakun Fig 2a 

Figure 2: Average global temperature (blue), Antarctic temperature (red), and atmospheric CO2 concentration (yellow dots).  Source.

Last updated on 21 April 2021 by eckahle. View Archives

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Further reading

That CO2 lags and amplifies temperature was actually predicted in 1990 in a paper The ice-core record: climate sensitivity and future greenhouse warming by Claude Lorius (co-authored by James Hansen):

"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"

The paper also notes that orbital changes are one initial cause for ice ages. This was published over a decade before ice core records were accurate enough to confirm a CO2 lag (thanks to John Mashey for the tip).

Also, gotta love this quote from Deltoid in answer to the CO2 lag argument: See also my forthcoming paper: "Chickens do not lay eggs, because they have been observed to hatch from them".

Further viewing

Myth Deconstruction

Related resource: Myth Deconstruction as animated GIF

MD Lag

Please check the related blog post for background information about this graphics resource.

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Comments 226 to 250 out of 636:

  1. argument: It's not us Geophysical Research Letters Attribution of regional-scale temperature changes to anthropogenic and natural causes Science Penetration of Human-Induced Warming into the World's Oceans argument: Models are unreliable Nature Geoscience The equilibrium sensitivity of the Earth’s temperature to radiation changes
  2. The It's the Sun argument discussion provides links to 17 more peer-reviewed papers on this topic.
  3. #224: "Show me one peer-reviewed paper ... " How about Santer 2003: Our study shows that the increase in tropopause height over the second half of the 20th century was predominantly due to human activity, and provides independent support for claims of recent tropospheric warming. And Hegerl et al 2011: we find that external forcing contributes significantly (p<5%) to the reconstructed long-term variability of winter and spring temperatures and that it is responsible for a best guess of 75% of the observed winter warming since the late seventeenth century. This warming is largely attributable to greenhouse-gas forcing. A more appropriate thread for this fish-in-a-barrel is It's not us.
  4. "Show me one peer-reviewed paper that has ruled out unicorn farts as the cause of most of the recent warming in the thermometer record." They can't! It's a conspiracy!
  5. Alleagra, Wow, Spencer is doing a merry dance...and the goal posts keep shifting so much and so far that it is a wonder anyone can keep up...perhaps that is the point. How about this Spencer....you please show us a peer-reviewed paper (published in a reputable journal please)which demonstrates that most of the observed warming to date is from natural forcing. I do know of a paper off the top of my head which addresses his loaded question (sounds like a similar situation to Lindzen cherry-picking 1995 in the HadCRUT record), but I will have look. I suspect Spencer has scoured the literature and carefully formulated his question so as to try and claim a "gotcha". We'll see... Oh, already found one, Schwartz et al. (2010): ".....and cooling by natural temperature variation can account for only about 15%." And "The standard deviation of the difference in temperature over 150-yr intervals for the period (1000–1850) based on the synthesis reconstruction of Juckes et al. (2007) yields 0.2 K, which is 25% of the observed increase in GMST (Fig. 2). Somewhat smaller changes in GMST were found in simulations of the twentieth century with coupled ocean–atmosphere global climate models using estimated natural forcings only (as reported by Solomon et al. 2007, see their Fig. 9.5), which for 19 runs with 5 models yielded a temperature increase of 0.09 K (standard deviation is 0.19 K, maximum is 0.49 K)" Spencer might also want to try and explain what is causing the planet to be in a net positive energy imbalance (see Murphy et al. 2009). One cannot blame that on internal climate variability, nor can one blame it on solar. Also from Murphy et al. (2009): "After accounting for the measured terms, the residual forcing between 1970 and 2000 due to direct and indirect forcing by aerosols as well as semi-direct forcing from greenhouse gases and any unknown mechanism can be estimated as −1.1 ± 0.4 W m−2 (1σ). This is consistent with the Intergovernmental Panel on Climate Change's best estimates but rules out very large negative forcings from aerosol indirect effects." Then there is Foster et al. (2010), in which they state: "Trenberth et al. [2002] found a residual global mean surface temperature trend of 0.4°C over the period 1977–1998 after ENSO impacts alone are removed. More recently, Thompson et al. [2008] removed an estimate of global temperature variations associated with both ENSO and the so‐called cold ocean/warm land or “COWL” pattern of extratropical temperature variation, and found a residual global mean surface warming of 0.4°C over the 1950–2006 period. In all of these previous analyses, ENSO has been found to describe between 15 and 30% of the inter seasonal and longer‐term variability in surface and/or lower tropospheric temperature, but little of the global mean warming trend of the past half century." Where the residual refers to the anthropogenic component. Trenberth et al. (2002) found that: "For 1950–1998, ENSO linearly accounts for 0.06 C of global surface temperature increase." And there are more where those came from....what does Spencer think he is trying to pull here? These games being played by those in denial about AGW/ACC (and it seems now that Spencer is officially in denial about AGW) disgust me. Spencer is just providing fodder for the "skeptics", who will lap anything up it seems so long it fits their preconceived (and misguided)ideas.
  6. hey guys, i am an engineer so i am no expert in the field of climate science however i am deeply interested. i take quite a neutral position on whether CO2 is driving the climate, there still seems to be strong scientific debate over the issue despite being told that 'the science has been settled' by the majority of the media. I was just wondering have you guys seen the work of Dr. Ferenc Miscolzi? he has published quite a few papers. His conclusions are that there is a constantly maintained green house gas factor that cannot be changed with further emissions alone. He claims that there would be an equivalent amount of water vapour withdrawing from the atmosphere as the CO2 rises. I'm interested to hear standpoints on his work. Thanks
  7. #231: "there still seems to be strong scientific debate over the issue" It's not really a debate; that would imply some sort of parity between the two sides. If you look around this site for any length of time (and you should), you will quickly realize that most denier positions fall flat on their face. "despite being told that 'the science has been settled' by the majority of the media" What media do you watch? Most of the media ignores climate change as a political hot potato -- and those who do talk about it feel compelled to pretend it needs a 'fair and balanced' presentation. "the work of Dr. Ferenc Miscolzi" Very convincingly shown to be false here. Before falling for a fringe theory, it would be best to read up on the basics here at SkS. Start with the newcomers guide, then read through the rebuttals to the common skeptic arguments.
  8. I have never heard of Dr. Ferenc Miscolzi and can't find any published work by an author of that name. Can you provide any citations? That claim is in direct contradiction to many different lines of empirical evidence. argument: CO2 effect is weak argument: Water vapor is the most powerful greenhouse gas
  9. @228 - The Santer paper is not good science. How in the world did Science actually publish such a weak, sloppy, illogical mess like that? I am not impressed. Is Santer kidding?
    A model-predicted fingerprint [human, I will assume he means] of tropopause height changes is statistically detectable in two different observational (“reanalysis”) datasets.
    It is a model, folks. Models are not empirical evidence. First of all, Santer is using tropopause height as a proxy for, not warming, but he takes it to an unwarranted next step, bypassing the warming itself and going straight to "humans did it." His statement should have been in two parts. First it should have said, "We show that tropopause height is a quantifiable proxy for a warming climate," and then he should have shown his evidence that it was humans that caused the tropopause height change. His logic is flawed. His CO2 = humans thinking is getting in the way of his logic.
    Increases in tropopause height over the last several decades have been identified in radiosonde data (2), in observationally-constrained numerical weather forecasts (reanalyses) (3), and in climate models forced by combined natural and anthropogenic effects (4).
    Wow. The only empirical evidence here is the first, radiosonde data, and it is only evidence that the tropopause has changed. Nothing in that fact points at humans. The 2nd one is weather forecasts, and forecasts are not empirical evidence. They are guesses. The 3rd is climate models, and models are not empirical evidence, either. So all he is left with is "Weather balloons say the tropopause changed height." That says nothing about humans. To Santer maybe it does, but it isn't scientific to take that quantum leap. Santer: In logic you can't leave steps out.
    Model experiments suggest that this increase cannot be explained by natural climate variability alone (4).
    Again, models are not empirical evidence. They are lines of code and can only give back what is programmed in. GIGO anyone? I am not slurring the modelers intentions, just that they need each physical process to be 100% proven out before they can rely on the output of that portion of the code. And they also need to not include even one code character of supposition or surmise or assumption.
    To date, no study has quantified the contributions of different anthropogenic and natural forcing mechanisms to tropopause height changes over the 20th century.
    THIS one is beautiful. Santer here is admitting that as of 2003 no one - I repeat, no one - had done what Dr. Spencer is asking in 2011. So, the first question should be, "Has anyone done it since then?" Of course, in this paper Santer is claiming that he and his cohorts have come to rescue climate science from that oversight. But has he?
    We estimate these contributions here, and demonstrate the usefulness of tropopause height as an integrated indicator of human-induced climate change.
    Sorry. Demonstrating based on estimates? Not science. I think he can do better than that. Really guys, this is not well done. On this site where you claim to be properly skeptical, you don't let that pass as science, do you? And this one in the Abstract caught my eye:
    Tropopause height changes simulated over 1900-1949 are smaller than in recent decades, and are driven largely by variations in volcanic aerosols and solar irradiance.
    I'll even pass on the "simulated" and get to the real goody: This is the same solar irradiance that has been shot down as a direct and naturalforcing for warming itself, but it is okay for Santer to drag it out and claim a causal link to tropopause height? For a proxy? Wow. That sure seems to be a double standard. But at the same time, let's see what Santer does with it... Okay, he only mentions it twice in the body of the text. The first is
    The natural external forcings considered are changes in solar irradiance (S) and volcanic aerosols (V)
    where he assigns a variable name to it. Okay... No real science there. . . Then the last mention of solar irradiance is:
    Solar irradiance changes over the 20th century warm both the troposphere and the stratosphere with offsetting effects on tropopause height.
    First here, let's point out that this is the only meaty (?) use of solar irradiance in the entire paper. But this is puzzling. Without any sourcing, he states it as fact, leaving everyone else (I guess) to stipulate that it is an uncontested fact. But, wow. He is giving solar irradiance a power that isn't referenced and a power that isn't allowed to anyone who tries to use it as a direct forcing on climate warming directly, who want to use it as a "natural forcing." They can't use it directly, but he can use it as a forcing - for a proxy - with no demonstrated evidence that it is even really true. Do I have that right? He can't do that. VERY poor logic, sloppy concepting of the paper - what can I say? Terrible... And in conclusion, nowhere in it does Santer develop an answer to Dr. Spencer's challenge. Models and simulations and estimates - none of them are empirical evidence that does what Santer claims it does. Solar irradiance - if he wants to use that for proxies, he has to "show his work," and prove why it is valid to use it. And then allow everyone else to use it. Seriously, if I were a grading it as a paper, I'd flunk the dude.
  10. Feet2thefire is plainly in complete ignorance of the logical place of models in science. A model is a set of mathematical formula that encapsulate a combination of known physical laws and some proposed theory. For any models other than the simplest, they need to be run on computers because of the number of calculations involved. For even moderately complex climate models they need to be run on super computers. But that does not change their logical basis. Because a model is a set of mathematical formulas encapsulating a theory, the output of a model run is just the prediction of that theory for a given set of initial conditions. (In chaotic systems, its a little more complex than that, but that's basically it.) So, and obviously, model outputs are not evidence. But that does not mean they are irrelevant. When Santer says, "Model experiments suggest that this increase cannot be explained by natural climate variability alone.", that means that no theory using natural variability alone as inputs predicts the observed increase in tropopause height. Just to make this quite clear. Models (and hence theories) including anthropogenic influences predict the increase in tropopause height. But no model (and hence theory) not including anthropogenic influences predicts the increase in tropopause height. This fact is not, of course, evidence. It is, however, proof that the increase in tropopause height is evidence of anthropogenic influence. Feet2thefire's slovenly argument is simply a demand that emperical observations (even if only with radiosonde) be not counted as evidence against theories that don't predict it; and not be counted as evidence for theories that do. It is a de facto demand that science be evidence free. I have not gone through all of Feet2thefire's endlessly turgid and repetitive spammed responce. I did note in passing a few blatant errors. Reanalysis is not, for example, weather forcasting. But what struck me most was the obtuse nitpicking. Obtuse because the nitpicks is clearly based on a total failure to understand what is said. They reveal Feet2thefire to be a scientific illiterate. Just one example. He picks fault with Santer for saying, "To date, no study has quantified the contributions of different anthropogenic and natural forcing mechanisms to tropopause height changes over the 20th century." (My emphasis) According to him, this is an admission by Santer that as of 2003, nobody had answered Spencer's challenge. But for his responce to make any sense, tropopause height would need to be the only possible signal of anthropogenic climate change.
  11. I keep having a ground hog day.
  12. Bibliovermis - Miskolczi is a crank. You can see a quick summary of what he postulates here
  13. #237 scaddenp at 06:31 AM on 4 February, 2011 Bibliovermis - Miskolczi is a crank. You can see a quick summary of what he postulates here Some may want to check what Dr. Miskolczi (and others) actually say about a possible upper bound on atmospheric IR optical depth due to IR absorber (a.k.a. "greenhouse") gases in a planetary atmosphere with practically infinite potential supply of IR opacity instead of accepting at face value the rather hasty debunking provided by RC Wiki (a supplement to the RealClimate.org community blog). Energy & Environment, vol. 21, num. 4, 2010 ISSN 0958-305X Special issue - Paradigms in Climate Research Guest Editor: Arthur Rörsch Dr. Miskolczi's paper is on page 243, but one may be interested in other papers in the same issue as well.
  14. Berényi Péter #237 Hasty debunking? What part of the hasty debunking do you disagree with? You do realize that the "RealClimate.org community blog" is a community of practicing climatologists don't you? As for E&E, it is my understanding that it is not a peer review journal and has a rather dubious reputation of publishing less than scholarly science?
  15. #238: "the rather hasty debunking" Even Spencer shoots FM down. I have spent many hours examining it and thinking about it, ... I disagree with his explanation of why the atmosphere’s total greenhouse effect should remain the same, particularly his use of Kirchoff’s Law of Radiation. Doesn't sound hasty.
  16. The guest editorial speaks to the credibility of the journal in general.
    The voices of well known scientists opposed to this dominant paradigm (e.g. Lindzen, Spencer, Singer, Christy McIntyre, Pielke, Khandakar), and backed by their own research, have been less clearly heard. ... Doubts about the mainstream "CO2-paradigm" arise because there is so little evidence from direct observations to support the framework that has been constructed from computer model studies/experiments. ... However, so far, we can see no sign that the protagonists of the IPCC line on expected Dangerous Anthropogenic Global Warming (AGW) are willing to consider any alternative to the CO2 paradigm.
    Dr. Sonja Boehmer-Christiansen, Editor, Energy & Environment
    I myself have argued the cause of climate 'realism' - I am a geomorphologist by academic training before switching to environmental international relations - but do so on more the basis of political rather than science-based arguments. As far as the science of climate change is concerned, I would describe myself as agnostic.
    Over a hundred years of empirical research by thousands of independent scientists merits the term "AGW hypothesis", while a single work that is contradicted by observational records merits "Miskolczi theory"? This is a prime example of a political rather than science-based argument. It's amusing that Miskolczi's work, a model based on simulated effects, is being pushed by those who decry the vast bulk of climatological research as invalid for being nothing more than models & simulated effects.
  17. Bibliovermis @241, Very interesting (and revealing )post. Regarding this from E&E: "The voices of well known scientists opposed to this dominant paradigm (e.g. Lindzen, Spencer, Singer, Christy McIntyre, Pielke, Khandakar)". McIntyre is not a scientist. And Singer is, well, a scientist for hire it seems, and seems to have some intriguing ideas on climate science. Khandakar is not a prominent climate scientist and of late his reputation has fallen into disrepute in the scientific community. Lindzen's iris hypothesis remains that, a hypothesis. The "skeptics" do love to hammer away at the models, forgetting that Pielke, Lindzen, Spencer etc. all use models in their research. Not to mention that one doesn't require a model to estimate climate sensitivity for a doubling of CO2. And look at all those pejorative words "paradigm", "protagonist", "dominant"....
  18. Albatross... " Lindzen's iris hypothesis remains that, a hypothesis. " One could easily qualify that and say that Lindzen's is a hypothesis in tatters.
  19. #239 RickG at 10:17 AM on 4 February, 2011 You do realize that the "RealClimate.org community blog" is a community of practicing climatologists don't you? I do realize it is a community of climate policy makers who try to do some science in their spare time, as they are posting there regularly in office hours. Check the timestamps. As for E&E, it is my understanding that it is not a peer review journal It is. However, neither the Nick Stokes rebuttal at RC Wiki from Jun 2008 nor Rebuttal of Miskolczi’s alternative greenhouse theory by Van Dorland & Forster are peer reviewed publications for sure. Therefore citing them here somewhat goes against the rules at this site.
  20. 244 Berényi Péter: I do realize it is a community of climate policy makers who try to do some science in their spare time, as they are posting there regularly in office hours. Check the timestamps. So, Gavin Schmidt, Michael Man, Caspar Ammann, Rasmus Benestad, Ray Bradley, Stefan Rahmstorf, Eric Steig, David Archer, Ray Pierrehumbert, Thibault de Garidel, Jim Bouldin and many others are just climate policy makers. Well, I'm glad we cleared up that bit of information. As for E&E it is not listed by ISI as being a peer review journal and Scopus lists Energy & Environment as a trade journal. Again, what do you specifically disagree with in the "hasty debunking"?
  21. BP - Nonetheless the assertions by Nick Stokes are easily checked in a text book. The lack of peer-reviewed rebuttal may have something to do with those who do atmospheric science having better things to do. Get back to me when there is peer-reviewed research (other than E&E) that builds on his paper with empirical results. The "peer-review" of E&E allows it to fulfill the function of tobacco science journals. It would be career damaging to publish there and you would be mad to publish a real scientific result there. Pseudo-skeptics strenuously argue that this should not be true, but that is the reality, like or not.
  22. Berenyi Peter @244, I'm just wondering how much peer review you need to recognize that a well known physical law is completely misstated? Better yet, what type of peer review can't even recognize the misstatement of a well known physical law?
  23. Berényi Péter at 12:04 PM on 4 February, 2011
    "I do realize it is a community of climate policy makers who try to do some science in their spare time, as they are posting there regularly in office hours. Check the timestamps."
    Oh dear Peter, your prejudices are showing! The RealClimate "community" are extraordinarily productive scientists. We could look at the first two on RickG's list just above, for example, and find that Gavin Schmidt has published since 2005 more than 40 papers (in real science journals) which have been cumulatively cited well over 1000 times, and that Michael Mann has published over 40 papers since 2005 that have been cited around 800 times.... these are truly impressive records of scientific productivity during the period they (and others) have been running RealClimate.org. I wonder whether you misunderstand the nature of science in the modern world. Every grant application we write, for example, must include descriptions on how our research results will be disseminated, and the enhancement of public understanding is a fundamental element of the scientists role. Schmidt and Mann and the "community" at RealClimate illustrate how a straightforward and honest application to obtaining and disseminating knowledge go hand in hand. And while their "timestamps" indicate that they may fulfill some of their public understand roles during office hours (and why not?) you can be sure that like most scientists that work in the public sphere, they will be doing science outside of office hours too! Peter, do we really want our scientists to be "office drones"? Of course not...we want them to be insightful and productuve and their work to be useful and influential....rather like the "community" at RealClimate
  24. #241: "because there is so little evidence from direct observations to support the framework" Oh, that's rich. There's so little evidence. Any doubts about the total lack of credibility of the editors of E and E?
  25. Dr. Roy Spencer's rebuttal is also linked at the RC Wiki page. It is a bit funny, because he starts by misquoting Dr. Miskolczi. “for..two regions (or bodies) A and B, the rate of flow of radiation emitted by A and absorbed by B is equal to the rate of flow the other way, regardless of other forms of (energy) transport that may be occurring.” From a logical point of view it looks like a proposition, does not it? However, if the full context is included, it is clearly a definition (of the term "radiative exchange equilibrium"). “It will be convenient here to define the term radiative exchange equilibrium between two specified regions of space (or bodies) as meaning that for the two regions (or bodies) A and B, the rate of flow of radiation emitted by A and absorbed by B is equal to the rate of flow the other way, regardless of other forms of transport that may be occurring.” Now, in logic there is a difference between propositions and definitions. One does not even have to be a climate scientist to see it. Propositions can have a truth value assigned to them, while for a definition it simply does not make sense. Shortly afterwards he admits he does not understand a couple of the claims he [Dr. Miskolczi] makes. The actual situation looks worse than that. He does not even seem to be able to tell claims and definitions apart. But let us elaborate on the concept "radiative exchange equilibrium" (defined above) some more, just to see how much sense it makes. If regions both A and B have uniform, well defined temperatures, radiative exchange equilibrium simply means thermal equilibrium, that is, their temperature is the same (TA = TB). It is not particularly interesting, but neither is it the case for the climate system. Although below about 50 km mean free path of air molecules is short compared to their coupling strength to EM radiation background (plenty of collisions occur between absorption/emission events), that is, local temperature is pretty well defined everywhere, temperature distribution is usually far from being uniform. One can still define average temperature for regions like that, even if it does not make much sense to compute averages of intensive quantities. However, it looks like a standard practice in climate science and at least for the time being let's go with it. Now, for subsystems A and B not in thermal equilibrium themselves it is perfectly possible for them to have the same average temperatures while maintaining a steady nonzero net radiative heat flow between them. It is also possible of course for the two subsystems to have different average temperatures while being in radiative exchange equilibrium (in the sense defined above by Dr. Miskolczi). One can not emphasize enough how sharp is the difference between equilibrium and steady states. Unfortunately they are quite often mixed up in climate discussions (even in some peer reviewed pieces). I do not know what the actual net radiative heat fluxes are inside the climate system, much less their global averages, but I do see Dr. Spencer attacks a straw man he himself created. It would be his personal problem, were his misguided analysis not linked by RC Wiki with no comment whatsoever. This fact alone shows the blog community there is more interested in appearance of debunking than in thorough understanding and well formed argumentation.

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