The Great Climate Change Debate: William Happer v. David Karoly, Part B

By Andy May

In Part A of the Great Debate series (see here) we discussed Dr. David Karoly’s and Dr. William Happer’s arguments regarding how unusual the recent global warming is and how we know the recent observed increase in CO2 is due to human activities. In Part B we will examine their thoughts on questions three and four.

3. How do we know that the increase in CO2 and other greenhouse gases in the atmosphere have caused most of the recent global warming?

4. Climate models have been used to compute the amount of warming caused by human activities, how accurate are they?

For an introduction to the debate and links to the original documents see Part A.

3. How do we know that the increase in CO2 and other greenhouse gases in the atmosphere have caused most of the recent global warming?

Karoly’s first argument is an appeal to the “consensus.”

“Nevertheless, an overwhelming consensus of climate scientists agree that human-caused climate change is happening, and that global warming will continue throughout the current century, with many adverse impacts on human and natural systems.” From the Karoly statement.

Happer’s detailed response contains his view of “consensus science.”

“Truth has never been determined by “an overwhelming consensus,” and in fact, consensuses have often been completely wrong.” From Happer’s detailed response.

In Karoly’s statement, he goes straight into a discussion of how we know much of the increase in CO2 concentration in the atmosphere is from humans (see previous question in Part A, note Happer agrees the increase in CO2 is due to human activities) but provides no more evidence that CO2 and other greenhouse gases have caused most of the recent warming. For the calculation of the greenhouse gas contribution, he turns to climate models.

How computer models are used to separate natural warming from human-caused warming:

“… climate model simulations have been used to assess the relative importance of different forcing factors on the climate system and how well they explain the observed global warming. The simulations are driven by natural forcing factors, such as changes in solar radiation and volcanic aerosols, as well as human-caused changes in greenhouse gases and human activity-related climate forcing factors, including industrial aerosols and land use change.” From the Karoly statement.

Karoly refers to a whisker plot from the IPCC AR5 report (Figure 3) which shows the impact of human and natural “climate forcings” as computed by the climate models from 1951-2010.

Figure 3. The assumed temperature changes due to GHG (greenhouse gases), ANT (anthropogenic), OA (other anthropogenic), NAT (natural forces), and INT (internal climate variablity) from 1951 to 2010. Source Figure 10.5 from (IPCC 2013) page 884.


Karoly also provides the following illustration of the reasons we “know” humans are causing global warming (Figure 4).

Figure 4. Reasons that we know humans are causing [some] global warming. Source


Most of the reasons given are related to human CO2 emissions, which both Happer and Karoly agree are the main cause of the rising CO2 concentration in the atmosphere and oceans. The principal disagreement between them is how much warming is caused by CO2. The tropopause rises as the surface warms, this is not controversial. Karoly believes that since winter is warming more than summer and nights more than days, this excludes solar variability as a cause of the warming, perhaps this is so. But, none of the reasons given exclude internal variability (mainly ocean cycles).

The cooling upper atmosphere (stratosphere) could be due to more CO2, since CO2 radiates a lot of infrared radiation (IR) to space from the stratosphere. It could also be due to increased shielding of thermal radiation from below due to additional IR absorption in the troposphere. But, regardless of the cause, there is a noticeable correlation between the observed tropospheric warming and the stratospheric cooling in the atmosphere. For a discussion of the significance of the correlation, displays of the data and additional references see Munshi, 2018 (Munshi 2018). Thus, the essence of the debate is not if CO2 warms the lower atmosphere, the argument is about how much warming is due to CO2 and other greenhouse gases. More detail on Figure 4 and references can be seen at this link by John Cook.

Happer points out at the beginning of his statement that CO2 levels today are much lower than during almost any time in the history of life on Earth. Figure 5 shows the history of CO2 levels for the past 550 million years.

Figure 5. History of CO2 levels for the past 550 million years. Source: (Berner and Kothavala 2001).


Happer writes this about Figure 5:

“The important message of Fig. [5] is that CO2 concentrations have been much higher than present values over most of the history of life. Even though CO2 concentrations were measured in thousands of parts per million by volume (ppm) over most of the Phanerozoic, not the few hundred ppm of today, life flourished in the oceans and on the land. Average pH values in the ocean surface were as low as pH = 7.7, a bit lower than the pH = 8.1 today. But this was still far from acidic, pH < 7, because of the enormous natural alkalinity of seawater. The mean global temperature was sometimes higher and sometimes lower than today’s. But the temperature did not correlate very well with CO2 levels. For example, there were ice ages in the Ordovician, some 450 million years ago, when the CO2levels were several thousand ppm.” (Berner and Kothavala 2001) and (Quinton and MacLeod 2014) From Happer’s statement.

Tamblyn writes the following about the same graph and a separate, but similar one in his detailed response:

“Lest we wonder how the Ordovician ice age could have occurred … GEOCARB III (which Professor Happer also references) is a geochemical model, which estimates past CO2 levels from the chemistry of rocks. Its calculations are run over steps of 10 million years and averaged over 50 million years. It is not sensitive enough to detect shorter-term changes. Direct geological evidence shows that CO2 levels fell sharply during that period, in 1 to 2 million years or less — too small for GEOCARB III to capture. A higher-resolution geochemical model applied just to this period suggests a decline of CO2 levels from ~5000 to 3000 ppm. With differences in solar output, 3000 ppm then is equal to 500 ppm today. Climate models applied to late Ordovician conditions predict icehouse conditions at CO2 levels below about 2240 to 3920 ppm.

The explanation is that changes in the greenhouse effect over time, due to changes primarily in CO2 and methane levels, explain much of the observed climate history. They aren’t the only factors. Orbital cycles influence how much sunlight the Earth receives. The extent of snow and ice changes how reflective the Earth is. The position of the continents matters (land reflects more sunlight than the oceans), and continents shape the flow of ocean currents, influencing heat transport. For around 30 million years, Antarctica has been isolated and surrounded by a huge current, the Antarctic Circumpolar Current, promoting cooling. For many, hundreds of millions of years before, this wasn’t so.” Tamblyn detailed response.

So, 3000 ppm in the Ordovician ice age is equal to 500 ppm today, yet we are currently at 400 ppm? Tamblyn’s point about resolution is valid but does not prove his case and his numbers are inconsistent with his thesis. He lists many valid influences on climate but fails to make the case that CO2 is the dominant influence. The quoted passage appears to weaken Tamblyn’s case and strengthen Happer’s.

4. Climate models have been used to compute the amount of warming caused by human activities, how accurate are they?

Karoly explains that natural forces are separated from human influences on climate with more than 30 computer models that compare well to observations since 1860 and writes:

“The observed significant cooling for one to two years after major volcanic eruptions —Santa Maria (1903), Agung (1963), El Chicon (1982), and Pinatubo (1991) —is simulated very well. The observed global mean temperature variations throughout the whole period lie within the range of all the model simulations with combined forcings, indicating the models simulate well the chaotic interannual variability of global mean temperature. There is very good agreement between the observed long-term global warming since the late nineteenth century and the average global warming across all the model simulations for combined natural and anthropogenic forcing.” From the Karoly statement.

He shows the following illustrations (Figure 6) from IPCC AR5 (IPCC 2013):

Figure 6. (a) The ensemble mean of numerous CMIP3 and CMIP5 climate models are shown in blue and red and compared to observations shown in black. The range of modeled results is shown with yellow and gray shading. The minimum warming in (a) from the models can be almost a degree C lower than the maximum model value for any given date and the error increases with time. This display models both human-caused and natural warming. (b) Same as (a) but only natural warming is simulated. (c) Same as (a) but only greenhouse gas warming is simulated. (c) suggests that net forcing (except for greenhouse gases) is negative, since natural forcings are assumed to be zero by the IPCC, they claim the negative forcings are “other anthropogenic.” The temperature anomalies are computed relative to the mean from 1880-1919. Source IPCC AR5, figure 10.1 (IPCC 2013) page 879.

Thus, the evidence for the magnitude of the human impact on climate is entirely model-based and direct measurements of the impact have not been made. Critics also point out that the warming from 1910 to 1945 and 2000 to 2012 are poorly matched by the models. Karoly responds:

“Of course, a small number of scientists say that the climate models are tuned to simulate the recent observed warming but are unreliable for projecting future warming trends. Others say that they show too much global warming, because the observed warming from 1998 to 2010 was very small, while the simulated warming continued, if you consider the average across all the climate model simulations. As shown already when considering the observed global mean temperature variations, there is large natural variability in global mean temperature in the observations and the models. The observed departure in 2010 from the multi-model mean is no larger than in 1910 or in 1940 and is well within the envelope of all the model simulations.” From the Karoly statement.

Thus, the poor reproduction of 1910-1945 and 2000-2012 is acknowledged, but in Karoly’s opinion the mismatch is acceptable. The error from 1910 to 1945 ranges from -0.2° to +0.4°C, approximately equal to the warming from 1975 to 2010, but human emissions of CO2 were not considered (or modeled) to be significant before 1951. How interesting that both sides use the poor model match from 1910-1945 in their arguments, but with opposite intent.

Happer has the following to say about using climate models to “prove” global warming since 1951 is primarily due to human activity:

“I disagree. This statement is based on excessive faith in computer models. The wide availability of computers and powerful software to make color displays has been a serious problem, since it has blurred the lines between reality and virtual reality. These are not the same. In my Statement and Interview I tried to stick to real satellite pictures of visible and thermal radiation from the Earth, real measurements of ocean pH, real records of tornados, hurricanes, floods, droughts, etc. Essentially all of Dr. Karoly’s claims of warming from greenhouse gases come from computer models, with lurid, threatening reds to represent the supposedly harmful effects of the demon gas, CO2.” Happer’s detailed response.

What is coming next?

The answers the scientists give to these questions highlight a significant and key difference in interpretation. Karoly is comfortable with the results from the climate models and Happer is not. As a result, Karoly is comfortable with the model-based conclusion that CO2 and other greenhouse gases are responsible for most of recent warming. Happer is not convinced the models are accurate and provides his own calculations and observations that show far less warming from CO2. Part C of this series will discuss their thoughts on the accuracy of future temperature estimates. It examines questions five and six. These are:

  • How do we know global warming and more CO2 will have substantial adverse impacts on humans and the planet?
  • Should anything be done to combat global warming?

Equilibrium Climate Sensitivity (ECS) to a doubling of the CO2 concentration has not been measured and is poorly estimated, the IPCC range of possible values is 1.5 to 4.5 and it has stayed at this range since 1979. How much difference does this range make?

Works Cited

Berner, Robert, and Zavareth Kothavala. 2001. “Geocarb III: A Revised Model of Atmospheric CO2 over Phanerozoic Time.” American Journal of Science 301 (2): 182-204.

IPCC. 2013. In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, by T. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley. Cambridge: Cambridge University Press.

Munshi, Jamal. 2018. “Climate Change, Tropospheric Warming, and Stratospheric Cooling.” SSRN (SSRN).

Quinton, P., and K. MacLeod. 2014. “Oxygen isotopes from conodont apatite of the midcontinent US: Implications for Late Ordovician climate evolution.” Palaeogeography, Palaeoclimatology, Palaeoecology 404: 57-66.


78 thoughts on “The Great Climate Change Debate: William Happer v. David Karoly, Part B

  1. Having it both ways on the mismatch between the early 1900’s and late 1900’s-2010 warming fits one of the definitions of a fallacious argument It’s been over 40 years since I took the formal course in logic, but having a statement being both true and false in the same argument was a clear indication the logic was improper.

  2. “we will examine their thoughts on questions three and four.

    3. How do we know that the increase in CO2 and other greenhouse gases in the atmosphere have caused most of the recent global warming?”

    Here is where we get to the meat of the question. The answer to the attribution question is usually given in negative: We know is not any of the other know factors. Or it is derived from physical first principles using models that incorporate lots of unproven assumptions. The truth is that the CO2 hypothesis sinks in this question because they don’t have firm evidence that it is CO2. Models accuracy is a joke.

    The question of fingerprints is a red herring. Many are evidence that there is warming, or that CO2 is increasing. Not a single one is evidence that CO2 is doing it. That winter is warming more than summer and nights more than days does not discard solar variability. It points towards water vapor response (changes in air humidity) that could very well depend on solar variability affecting the oceans.

    The question of the Ordovician Ice Age is falsely responded. Although the faint young Sun paradox requires changes in GHGs it cannot be responded solely in terms of GHGs. The idea that the Sun’s increase in output was exactly matched by the decrease in GHGs to maintain thermal homeostasis over the Eons is preposterous. A firm contender to compensate solar changes is changes in albedo due to clouds. To say that 3000 ppm in the Ordovician is equal to 500 ppm now is unsupported. To say that 500 ppm (equivalent) is likely to promote freezing in the Ordovician and melting now is contradictory. I guess they don’t keep track of their lies.

  3. I have zero confidence in either the models written by climate alarmists (after all models are just hypotheses turned into code) or in the so-called climate “scientists”.

    The very fact that they use words like “consensus” and “denier” is a clear indication of a belief system, not a science.

    CO2 comes from many sources—most are natural, and its concentration increases as CO2 is released from reservoirs, which release CO2 when it’s warmer.

  4. Figure 3 is pure mythology and utterly depressing infantile fictitious nonsense.

    “Natural forces” is separated bizarrely from “internal variability” and both are essentially written off as zero. Climate ONLY changes by anthropogenic forcing.

    We sometimes half-jokingly accuse warmists of believing that the normal state of climate is stasis, not really believing that qualified and professional scientists, even biased by left wing politics, can achieve such a comprehensive failure to understand the natural world and complex-chaotic systems. And that they would have zero curiosity to learn about such systems.

    But, astonishingly, this actually appears to be the case. They really have persuaded themselves that all climate change is “deus ex machina” anthropogenic, “unnatural” and bad. That without humans climate would be static.

    What can one say? What basis can exist for rational debate? Except to point out that two important bars are missing from figure 3 (forcings of climate change). One is Thor’s hammer. The other is Storm from the Xmen. Both of these no doubt also dwarf natural variability.

  5. With differences in solar output, 3000 ppm then [the Ordovician] is equal to 500 ppm today.

    During the Ordovician, solar luminosity was about 95% of the current 1361 W/m^2. The forcing of 3000 Ordovician ppm can be estimated by taking 0.95 of the 5.35 Myhre coefficient. So, 3000 ppm produced 17.7 W/m^2 of forcing in the Ordovician, and produces 18.6 W/m^2 today.

    Likewise, 500 ppm today produces 14.4 W/m^2 of forcing and in the Ordovician produced 13.7 W/m^2.

    In the Ordovician 681.2 ppm of CO2 would have produced the same forcing as 500 ppm today.

  6. If engineers used ensembles of computer models in structural design the way they are used in climate studies, bridges would fall and buildings would collapse. Most engineering models are based on first principles and detailed knowledge of materials properties based on extensive empirical data. But they are also thoroughly tested and validated. I have, on occasion, been able to run several independently developed models on the same design and found agreement to be within +/- 1% on key results. If even one was off from the others by more than a couple percent, I would want to investigate further.

    I have also seen attempts to create computer models for some complex systems which try to use existing data, correlations, assumptions and fudge factors (usually called something like ‘correction factors’) to try and avoid the cost of building and testing prototypes. But no competent engineer would use such models without solid evidence of validation through thorough physical testing. In many cases, even well developed and accepted models are only relied on to develop a prototype which it then physically tested and instrumented so that measured performance can be compared to model predictions. Deviations between test data and model predictions must be investigated and explained before a project moves forward.

    When I see the “spaghetti plots” of the CMIP5 ensemble runs and the mean being claimed to have predictive skill it tells me the modelers are incompetent fools.

    Andy May – By the way, I’m enjoying you posts, Thanks.

      • glad to see the acknowledgement that even skillful models can sometimes get it wrong keith. highlights just how far off the mark the climate version of what constitutes a model is.

      • Keith Sketchley,
        It would appear that corporate politics and economics overrode the recommendations of engineers. Therein lies a cautionary tale about letting politics and ideology get involved with engineering and science.

    • One of the most senior climate modellers in Australia has a 1st class honours degree in mechanical engineering. My recollection is that he scored distinctions in all but one or 2 exams.
      Definitely no fool and far too sharp to be taken lightly in an argument. He has been modelling all his working life. He believes strongly in what he is doing. I disagree with the flawed cause and effect logic that his colleagues, like Karoly above, apply mainly on the grounds that an effect may have several causes but a cause, in isolation, will always result in the same effect.

      • 4 eyes, I’ve known a lot of very smart and very skilled modelers in my time. But, at the end of the day all you have is a model. If it isn’t validated for purpose, it is only an expensive toy.

        • Yep. Models are great heuristic tools… but only if you learn from the results. For 30 years, the climate models have consistently demonstrated that: 1) the modelers have underestimated non-GHG forcing and/or 2) overestimated GHG forcing… But they never adjust either. They just re-initialize the models and say “that after 1998, the observations are likely to be in the lower part of the model distribution, indicating that there is a small discrepancy between the model predictions and the satelllite observations.”

          In the oil & gas industry (and most other real world applications of science), their “small discrepancy” would be a total failure.

      • If two models of the same thing using the same inputs produce widely different results, either one or both are wrong. Claiming the average of the two is right is ridiculous.

  7. 3. How do we know that the increase in CO2 and other greenhouse gases in the atmosphere have caused most of the recent global warming?

    Karoly’s first argument is an appeal to the “consensus.”

    My response:

    Karoly should know that “consensus is NOT science” – a scoundrel or a fool would make such an argument.

    Learn the Scientific Method, for heaven’s sake Mr. K, before you speak again!

    4. Climate models have been used to compute the amount of warming caused by human activities, how accurate are they?

    “Karoly explains that natural forces are separated from human influences on climate with more than 30 computer models that compare well to observations since 1860 and writes:…”

    My response:

    The climate models produce nonsense too – they consistently run hot, have to be “tuned” (e.g. with false aerosol data) to even hindcast the past, and are clearly worthless as a predictive tool for the future.

    Karoly’s response is more nonsense prattling by a scoundrel or a fool.

    In summary:

    No wonder Karoly bailed out of the debate. His friends must have pulled him aside and said: “Get out when you can – you are embarrassing yourself – and us – with your total bullsh!t!”

  8. “Climate models applied to late Ordovician conditions predict icehouse conditions at CO2 levels below about 2240 to 3920 ppm.”

    OK. So its all to do with the SUN according to Climate models.
    Not much to do with CO2 after all!
    Isn’t that what we have been saying all of this time?

  9. I read somewhere that atmospheric water vapour or moisture content has increased abiut 0.7% or so over the same period as anthropogenic CO2 emissions. Given our farming irrigation practices and food production for population growth, surely changes in the GHG with grestest effect, H2O, needs to be plotted.

  10. So has this cleared the matter up?
    Well in as much as it has shown that definitive proof for either side is not very apparent.
    No one can show that CO2 has unduly warmed the atmosphere in the last 60 years or so, and no one can show that the recent climate is acting naturally, or not.
    What it has shown is that the consensus on each side are adamant that they are correct.
    On the AGW side though they have taken a step further in engaging in politics to ensure that their values and views hold sway within the communications to both governments and societies. And yet there is a large body of scientists, meteorologists, and lay people who are not convinced. In wondering why, maybe these AGW types should tone down the alarmism, and show why 1 to 3°C warming would be such a big problem — historically it never was much of one.
    Those advocating that the warming is all, or mostly, natural have the harder job of showing consistently, how the warming seen so far is entirely (or mostly) natural. On their side is the vast weight of historical records, archeology, etc., that can be reanalyzed to show how natural processes have functioned before.

    Neither side has shown that the increase in CO2 over the recent decades did, or didn’t, occurred mostly through natural agency. Also neither side can truly say, with evidence from validated and verified methods, what the future will (with a high probably) hold. The computer models thus far have proved themselves dire at making predictions. (IMO they require all code and methods used to be thoroughly audited by qualified outside ‘climate disinterested’ parties.) The consensus on both sides of the debate is world has warmed at a rate of about 1°C in a century; IMO that’s not alarming or unusual, and seems all very natural.

    What I find strange however is there’s a distinct possibility that the climate may cool, maybe a lot, maybe not. IMO it is a very real possibility, and no more far fetched than saying the planet will soon overheat as the AGW consensus claim. A solar minimum causing cooling of say 5 years or so, would put many additional stresses on local and global systems, are we prepared for these additional stresses?
    The world governments are slowly (and in some cases halfheartedly) but at great cost taking action just in case CO2 causes the world to overheat. However the solar minimum is now becoming a reality, and by historical evidence the weather should become more unpredictable, more extreme, where are the precautionary actions for the real possibility this planet may start cooling very soon?
    How quick would the younger generations identify the current batch of opportunists, lobbyist, NGOs, and politicians of this generation as the fools that lead so many to ruin or worse.

    • tomOmason I would disagree with you on one of your conclusions. I quote you: “Those advocating that the warming is all, or mostly, natural have the harder job of showing consistently, how the warming seen so far is entirely (or mostly) natural.”

      Proving that the warming is natural does not have to be done at all from a policy point of view. Natural causes is the null hypothesis and will continue to hum along entirely by nature as it always has with or without proof from man. No proof is necessary for natural causes, we already know they happen. The null hypothesis says the warming is entirely natural like it always has been unless proven to be otherwise.

      Here is what we know: CO2 appears to have some greenhouse effect in the lab and its reasonable to accept that man in increasing the CO2 content in the atmosphere. There is plenty of proof that CO2 is vital to life on this planet. We are carbon based units.

      Within the environment, CO2 does not appear to have a robust provable link to actual atmospheric warming and no link whatsoever to catastrophic warming requiring mandatory populations reductions through energy starvation.
      The smoking gun proof of anthropogenic global warming requiring drastic action is entirely on the side of the CAGW hypothesis and CAGW proponents have failed to even show a weak significant link, let alone, a strong significant link of CO2 to CAGW. They won’t even release their data.
      In my opinion, we have now wasted 30+ years on CAGW and expended very little on understanding the natural causes of climate change. As such we do not have a clue how to prepare to mitigate climate change from natural causes. We are as blind now as we were 30 years ago. We have gained nothing a great human expense.

      • “The null hypothesis says the warming is entirely natural like it always has been unless proven to be otherwise.”

        People should keep this in mind. Skeptics don’t have to prove that the warming is entirely natural. Skeptics should assume it is entirely natural until proven otherwise.

        Alarmists are the ones who need to provide proof that CO2 is causing unnatural changes in the Earth’s atmosphere. No proof has been provided to date so therefore we must assume that the climate is changing naturally as it always has and CO2 has little or nothing to do with it, until proven otherwise.

      • “Here is what we know: CO2 appears to have some greenhouse effect in the lab…”

        Therein lies the problem. The lab isn’t able to simulate the myriad feedbacks associated with the CO2 absorption, such as evaporation of water (increasing WV absorption of CO2), production of clouds (increasing albedo), and stimulation of photosynthetic organisms (and sequestration of CO2). Put more simply, the lab results are evidence being used ‘out of context.’ The lab results are only part of the big picture.

        • I would be most interested in those laboratory experiments that show some greenhouse effect. Someone please provide links to these. Looking for actual temperature change–“greenhouse effect”– and not simply absorption and emission of infrared. Thanks in advance.

      • Thank-you for the reply.
        You have some good points there.
        Also worth considering is how nature has controlled the chemistry of this planet’s atmosphere for billions of years but according to the cAGW advocates it does not control it now, apparently humans do — how weird is that?

  11. Here is a side story on computer models and why I take them with a grain of salt (or sometimes a block of salt). Prior to retirement, I was on a team of experts that visited and reviewed environmental remediation programs at military bases, primarily Air Force Bases, with the purpose of providing useful independent feedback to the bases that could be used to improve remediation effectiveness, reduce costs, among other objectives. At Edwards AFB, the chlorinated solvent groundwater plume under the main flight line extended towards Rogers Dry Lake (formerly Muroc Dry Lake). Modeling had been conducted to assess plume migration and it predicted the plume would migrate off site on the order of 100 plus years. The CA Water Board was already addressing the potential migration issue based on modeling projections. Our team reviewed the data and plume migration was not apparent from the leading edge groundwater data but the model was predicting plume migration. We made a series of recommendations including that the model be calibrated based on a certain data set and then validated. The results of our plume evaluation were summarized in a paper I presented in Monterey, CA in May 2010 with 5 coauthors. At the time, I was not following the AGW “climate science” but once I started, it was very easy to see the parallels. It’s all about climate scientists using unvalidated models and regulators acting on model projections which didn’t match the empirical data. I wouldn’t be surprised if others have similar stories.

  12. There is a paradox about perihelion and aphelion which shows that insolation per se has a surprisingly weak effect on global temperatures, one that is dwarfed by changes in atmospheric albedo, water vapour and clouds.

    From Wikipedia:
    Earth is about 147.1 million kilometers (91.4 million miles) from the Sun at perihelion around January 3, in contrast to about 152.1 million kilometers (94.5 million miles) at aphelion around July 4 — a difference of about 5.0 million kilometers (3.1 million miles). (These dates change over time due to precession and other orbital factors, which follow cyclical patterns known as Milankovitch cycles. For a table of these dates for various years, see Apsis.)

    Because of the increased distance at aphelion, only 93.55% of the solar radiation from the Sun falls on a given area of land as does at perihelion.

    The paradox is that at perihelion on 3 Jan, the earth receives 6.45% more insulation than at aphelion on 4 July. Out of an average insolation of 1367 W/m2, this means a difference of 88.17 W/m2. And yet perihelion is in NH winter, not summer. The cause of summer-winter temperature difference is clearly not insolation, but is the angle of irradiance through the atmosphere which is mediated by albedo, scattering, water vapour and clouds. All of these atmospheric factors – with water vapour chief among them – utterly overwhelm insolation, consigning it to practical insignificance.

    The end Ordovician ice age occurred with atmospheric CO2 of ~ 3000 ppm. This would appear to invalidate the claim that CO2 dominates global temperature. The CAGW counter-argument to this is the fig leaf of the “dim sun”. Our sun’s insolation of earth was 5% less back then than now, and this “huge” difference in insolation was exactly compensated by higher CO2 greenhouse effect. (This compensation is so exact and fortuitous as to practically comprise a design argument and an intelligent, benevolent creator!)

    But there’s a problem. 5% of insolation amount last to 68.35W/m2, which is less than the difference in insolation of 88.17 W/m2 caused every year, between January and July, by eccentricity and the perihelion-aphelion difference in earth-sun distance.

    Insolation by itself would make earth – both NH and SH, warm in January and cold in July. But it does not because atmospheric processing of insolation by albedo is so dominant over insolation per se as to render insolation insignificant in the NH summer-winter difference. And this atmospheric albedo is in turn dominated by water vapour and clouds.

    In summary, consideration of perihelion-aphelion shows that atmospheric water vapour and clouds are crushingly dominant – probably by at least 2 orders of magnitude – over insolation per se, as a driver and controller of earth temperature.

    Note also the equally total insignificance of CO2 in the reversal of this 88 W/m2 insolation difference between summer and winter and the effective reversal of the NH seasons. Does CO2 concentration swing annually by about 3000 ppm to compensate for perihelion-aphelion? No.

    If it is so “easy” for atmospheric albedo dominated by water vapour and cloud, to reverse the perihelion-aphelion difference in insolation in the NH, in terms of NH summer-winter temperature, then it is clear that it is impossible for insolation per se to account for the “dim sun” paradox of the Ordovician ice age. Why invoke CO2 to compensate a difference in 68 W/m2 between the Ordovician and now, when a bigger insolation difference of 88W/m2 is compensated, every single year, by water dominated atmospheric albedo. When CO2 is irrelevant in this compensation for perihelion-aphelion?

    All of this shows how the processing of insolation by the atmosphere that results in actual earth surface temperatures, is overwhelmingly dominated by atmospheric water vapour and cloud. CO2 is demonstrably irrelevant.

    • In December-January, the continents in the Northern hemisphere are covered with highly reflective snow/ice in the higher latitudes. This is main reason why the Earth’s mean temperature is lower in December-January even though it is at perihelion (closest to the Sun).

      • Roger Taguchi

        In December-January, the continents in the Northern hemisphere are covered with highly reflective snow/ice in the higher latitudes. This is main reason why the Earth’s mean temperature is lower in December-January even though it is at perihelion (closest to the Sun).

        A very broad statement.
        For a true hemispherical earth of area 514 Mkm^2

        Show it is true by area calculations of total land area (each hemisphere, which we will assume is constant),
        area of maximum and minimum snowfall or ice on land in each quarter (22 Dec, 22 March, 22 June, 22 Sept),
        area of sea ice in each hemisphere on those same dates.
        TOA solar radiation on each of the same 4x dates.

        Your answer may require us to go into some calc’s for penetration of the TOA radiation to the flat surface of each 10 degree latitude band, but let’s get the easy numbers out of the way first.

    • Roger, RACook
      For snow and ice to be causing NH winter by albedo – while I don’t dismiss this – would it not seem a tad circular?

      Snow causes cold, cold causes snow.
      Is there time every autumn for such a positive feedback to build up?
      So every winter is a mini ice age?
      I can’t see it somehow.
      It must be something more directly related to the angle of solar incidence.
      The same reason why it’s colder at the poles (and would still be colder at the poles in the absence of any obliquity.)

      • You’re right, of course, that the summer/winter difference at any given latitude is mainly due to the tilt of the Earth rather than the distance to the Sun. However, the Earth’s mean temperature is lowest at perihelion, which is in early January. This is winter in the NH, but it is summer in the SH. The winter in the SH does not have the same extent of reflective snow/ice on the continents because most of the land masses are in the NH. Therefore the argument is not circular, but direct cause-and-effect.

  13. One can be very sure that David Karoly and the person he refers to John Cook (of the falsely name blog Skepticalscience) have no qualifications or even understanding of the subjects necessary to assess climate or climate changes eg heat transfer, fluid dynamics, reaction kinetic, evaporation & condensation (cloud formation), instrumentation etc. Karoly had to withdraw a paper because he did not understand statistics. He knows nothing of dimensional analysis or even basic engineering mathematics. He knows nothing about gain and feedback. He has no knowledge of geology and past evidence of changes on the earth.

    • Karoly co-authored the southern hemisphere hockey stick, Gergis was the lead author. I have little faith in the man.

  14. The danger of “models” is best shown here :
    Did a gamma-ray burst initiate the late Ordovician mass extinction?
    Imagine scrutinizing CO2 and being blindsided by such a GRB? Worse than the now-extinct large reptiles after the KT.
    Still, what replaced those doomed life-forms, basically us warm-blooded advanced masters of fire, should not willfully repeat the theater.

  15. From Karoly (Figure 4) cartoon: Less oxygen in the air. What? So plant life is down and not producing oxygen as we are seeing a greening of the earth?

  16. It’s not about the climate, it’s about control. A small Asteroid impact , or large solar flare (ie Carrington intensity) would help refocus the worlds attention in the proper direction.

  17. From Karoly;“… climate model simulations have been used to assess the relative importance of different forcing factors on the……” According the a very learn it person, J. Scott Armstrong, who did a study about climate models using the Principle Of Forecasting said that the creators of “climate models” break so many of the rules (72) they can not be use to make any forecast or prediction about future warming. Forecasting Guru Announces: “no scientific basis for forecasting climate”
    Anthony Watts / January 28, 2009. Game over Mr Karoly.

  18. If perihelion and insolation were the driving factors, you would expect a disaster in the SH, where orbital tilt reinforces insolation/perihelion factors. However, luckily for the planet, the much higher percentage of water surface area tends to moderate any effect.

    Couldn’t have designed things better for relative stability if I tried…

  19. Winter warming more than summer and nights more than days is from more water vapour in the lower troposphere.
    Cooling upper atmosphere (stratosphere) is from less water vapour up there.

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