Atmospheric Temperature and Carbon Dioxide: Feedback or Equilibrium?

R. Taylor writes in to Tips and Notes to WUWT with this. Anthony: If you shift Vostok temperatures by reasonable time lags, and use reasonable parameters for an equilibrium between temperature and CO2, you get predicted values for CO2 that closely match CO2 measurements in Vostok. Really simple and conclusive, but I don’t think anyone has done it before.

I’m always interested in posting others research, so here it is. – Anthony


Atmospheric Temperature and Carbon Dioxide: Feedback or Equilibrium?
R. Taylor

For several years, the suggestion that there is positive feedback between atmospheric temperature (T) and carbon-dioxide concentration (CO2) has dominated the scientific literature, and has become a fundamental assumption of climate science. Alternatively, the relationship between T and CO2 might be one of equilibrium. We can test models of each type by comparison with the Vostok record, first published by Petit, et al. (1999). The Vostok record contains about 3,300 determinations of T and 280 determinations of CO2, spanning the last 420,000 years.

Figure 1 shows the Vostok record; for clarity, the dates and measurements of T have been averaged in groups of 10, and those after 0 BCE are not shown (cf. Figure 4).

RTaylorFig1

Figure 1: Temperature and Carbon Dioxide Inferred from the Vostok Ice-core.

T ranges through about 13 °C in the record, and CO2 ranges through about 120 ppm. There are peaks and valleys of various amplitudes and durations, and changes in T precede corresponding changes in CO2 (Mudelsee, 2001). The resolution of the record improves as measurements become more recent.

The first quantitative model comparable to the Vostok record with feedback between T and CO2 seems to be that of Hogg (2008). Hogg simulated insolation and other factors over a given interval of 500,000 years to predict values of T and CO2. Figure 2 is rescaled from Hogg’s figure 2a, so T and CO2 have approximately equal amplitude.

RTaylorFig2
Figure 2: Temperature and Carbon Dioxide from Hogg’s Feedback-Model.

Feedback systems typically have characteristic amplitude and period. For this model, 1.7 °C is the characteristic amplitude of T, and 100,000 years is about the characteristic period. Adjusting the parameters of the model will change its amplitude and period, but these will be characteristic for any given set of parameters: Other amplitudes and periods will be suppressed.

Since the model assumes that CO2 has a significant effect on T, changes in CO2 happen before corresponding changes in T through a substantial portion of its cycle, viz. the latter portion of the rises to the peaks (cf. Hogg) and through essentially all of the subsequent declines. As previously mentioned, however, the Vostok record shows that changes in CO2 happen after corresponding changes in T. This lag is shown most clearly by large-amplitude features in the more recent portion of the record: CO2 rises hundreds of years after T rises, and falls thousands of years after T falls.

The substantially inverted lag of this feedback model confirms what is self-evident in an equilibrium model: A lagging entity can have no significant effect on a leading entity. For example, CO2 at a given time cannot affect the level of T that existed hundreds-to-thousands of years earlier.

A model of equilibrium between T and CO2 can be based on balance between temperature dependent processes that (i) release CO2 into the atmosphere and (ii) absorb it into the surface of the earth. If the temperature dependency is simply linear, we can express our model as:

CO2(t+l) = mT(t) + b

where t is time, l is the length of time required for CO2 to regain equilibrium after a change in T, m is the number of units that CO2 changes for a unit change in T, and b is the constant offset between units of CO2 and units of T.

Using this equation, we can predict a value for CO2 at some time in the future from each value of T. If we give l a value of 50 years after a rise in temperature and 8000 years after a fall in temperature, m a value of 10 and b a value of 270, and average the times and predicted values of CO2 in groups of 10, we obtain the predicted values shown in figure 3. The figure also shows the measured values of CO2 for comparison.

RTaylorFig3
Figure 3: Carbon Dioxide, Measured and Predicted by Lagged Temperature.

The output of the equilibrium model is consistent with the lag, spectrum and amplitudes of the record. The correspondence between predicted and measured values of CO2 indicates that CO2 is in temperature-dependent time-lagged equilibrium, and that the temperature dependence of CO2 is essentially linear through the Vostok range.

Let us turn our attention to the last 11,000 years, during which humans have disturbed the equilibrium between T and CO2. The most recent CO2 determination from the ice-core has a date of about 340 BCE. We can add an early-industrial-era value of 290 ppm at 1800 CE and a value of 365 ppm at 2000 CE to provide figure 4. The scaling in the figure is consistent with the
equilibrium model that fits the overall Vostok record, where a change of 1 °C in T causes a change of 10 ppm in CO2.

RTaylorFig4
Figure 4: Temperature and Carbon Dioxide since 9,000 BCE.

T and CO2 appear to have been in equilibrium until about 3,000 BCE. Over the 5,000 years since then, CO2 has risen increasingly above its natural equilibrium. By 1,800 CE, CO2 had risen to a level comparable to the highest in the Vostok record. During this time, T declined at a rate of 0.1 °C per thousand years, indicating again that CO2 has no apparent effect on T. The trends of this 5,000-year interval of excess CO2 are consistent with the equilibrium model, in
which T is independent of CO2.

The last 5,000 years are trivial compared to the 420,000 years of the Vostok record; of even less significance are the last 1,200 years. However, climate science has put great emphasis on the features of this interval, even though they fit within the noise-envelope. The “medieval warm period” spanned 800 CE to 1,200 CE; Vostok shows it wasn’t really warm, but wasn’t really cold either. The “little ice age” followed (although average T was barely lower), and ended after the low of -1.84 °C around 1,770 CE. By the early 1800s, T was higher than it is at present, and it has fluctuated within levels typical of the last 11,000 years since then. It is remarkable that climate hysteria should be based on noise-level changes in T over the last 200 years, which is an eye-blink in the Vostok record. It seems to be the superstition of our time.

In summary, the Vostok record indicates that CO2 is in lagged equilibrium with T and that, for the range of T in Vostok, the dependency of CO2 on T is essentially linear. Unnaturally high CO2 for the last 5,000 years has had no apparent effect on T. This empirical evidence supports a conclusion that there cannot be any significant feedback between CO2 and T. Such feedback would cause predicted T and CO2 to show fundamental disagreement with the lag, spectrum and amplitudes evident in the Vostok record.

It is impossible to say how enduring the feedback fallacy will be. However, any such model proposed in the future can be regarded as qualitative if it does not specify lag, characteristic amplitude and period, and as speculative if it cannot be compared to the Vostok record. Accordingly, any such model can be ignored.

If we may depart for a moment from objectivity, any such model should be ignored if its proponents declare that it shows polar bears are in peril, and you can save them by painting your roof white and burning nuts and corn in your car.

References
Hogg, A.M., 2008, Glacial cycles and carbon dioxide: A conceptual model. Geophysical
Research Letters, 35, L01701 (5 pp.).

Mudelsee, M., 2001, The phase relations among atmospheric CO2 content, temperature and global ice volume over the past 420 ka. Quaternary Science Reviews, 20, 583-589. Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pépin, L., Ritz, C., Saltzman, E. and Stievenard, M., 1999, Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature, 399, 429-436. http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html provides on-line data.

Code with data:

Is available upon request.

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62 thoughts on “Atmospheric Temperature and Carbon Dioxide: Feedback or Equilibrium?

  1. I am wondering, is there a trend in the increase of retired scientists, Dr’s etc etc speaking out against AGW?

  2. I wondered whether ‘global temperature’ showed a lagged response to solar output intensity?

    Does anyone have any similar analyses about that??

  3. So the Vostok core says there was a stable dependence of CO2 on temperature till 3,000 years ago, then CO2 started climbing away.
    An alternative scenario is that CO2 is still stable and there is systematic error in the Vostok CO2 readings?
    The records show that the Roman warm period was very fertile and apparently not affected by the low CO2.

  4. Thanks for the great link, Johnny Honda (23:31)!

    Further evidence of retired scientists being usurped by the payola of Big Oil. Pensions just ain’t what they once were, I guess.

  5. I find Figure 4 chart very surprsing – if temperature didn’t cause the massive increase in CO2 which started around 2000 years ago, what did?

  6. Sandy (00:36:39) :

    An alternative scenario is that CO2 is still stable and there is systematic error in the Vostok CO2 readings?
    The records show that the Roman warm period was very fertile and apparently not affected by the low CO2.

    Did the Romans ever invade Antarctica? ;-)

    They used a lot of slave labour to build growing terraces on hillsides in the Balkans, with plenty imported back to the homeland as needed. Could the records be skewed by that?

  7. Fits my suggestion that if there is extra warming of the air from whatever cause then the air circulation systems shift latitudinally, the hydrological cycle speeds up and the rate of energy transfer from surface to space increases.

    The shift due to human CO2 would be completely imperceptible in the face of what happens naturally when the oceans alter their rate of energy emission.

  8. The correlation looks pretty robust to me. They can’t accuse you of picking cherries either.

  9. M. Simon (01:45:33) :

    Looking at Figure 2 it looks like we get extremely rapid temperature increases followed by a natural decay – very like radioactive decay… Hmm…

  10. I question the linear assumption. As far as I can tell from theory the relationship between CO2 and temperature should be logarithmic.

  11. John A (02:37:33)

    The effect of more CO2 in the air is indeed one of logarithmic decline.

    However the temperature of the Earth is in my view not significantly affected by the composition of the air but rather overwhelmingly by the sun/ocean interaction.

    The thing that puzzles me most about Figure 4 is the disconnect over the past 5000 years between the much increased CO2 quantity and the virtual absence of a significant temperature variation.

    That would suggest human involvement producing virtually all the CO2 rise for the past 5000 years but that is not often suggested even by the IPCC which considers the human effect on CO2 to be a more recent phenomenon.

    Certainly the ocean energy content did rise during the 20th Century, perhaps there was even an overall rise throughout the 5000 years and that should have fed through to rising CO2 without our involvement. Then there is the question as to how well ocean energy content is linked to global air temperatures.

    If the hydrological cycle responds as effectively as I think it does then it may be that over a 5000 year term one could have rising ocean energy content but the air temperatures not fully reflecting that rise (if at all) due to the changes in the speed of the hydrological cycle.

    Thus one could get higher ocean energy content, higher CO2 in the air but relatively small and only temporary changes in global air temperatures.

    In addition I have often noted the discontinuity between relatively stable ice core CO2 levels and much more variable atmospheric CO2 levels.

    That discontinuity does need to be resolved. There may be something in the ice core analysis that does not give an accurate reflection of either or both of the levels of CO2 in the air or the variability of those levels.

  12. I don’t know why this is thought to be new. The IPCC Ar4 Sec 6.4.1 says

    The ice core record indicates that greenhouse gases co-varied with antarctic temperature over glacial-interglacial cycles, suggesting a close link between natural atmospheric greenhouse gas variations and temperature (Box 6.2). Variations in CO2 over the last 420 kyr broadly followed antarctic temperature, typically by several centuries to a millennium (Mudelsee, et al., 2002).

    followed by Fig 6.3, which has much the same information as the one here.

  13. Sandy (00:36:39) :

    So the Vostok core says there was a stable dependence of CO2 on temperature till 3,000 years ago, then CO2 started climbing away.
    An alternative scenario is that CO2 is still stable and there is systematic error in the Vostok CO2 readings?
    The records show that the Roman warm period was very fertile and apparently not affected by the low CO2.

    Google 19th century CO2 measurements. After reading some of that, tell me if you think Vostok is right.

  14. Climate can not heat without heating the oceans first. Air is not heating oceans; oceans get heated up by direct solar radiation (visible and UV), where back radiation of long-wave IR can maybe increase evaporation in the upper thin water layer, where IR gets absorbed. If sun is stronger or we get less clouds, ocean gets warmer and vice versa.
    Funny idea is, that main “greenhouse gas” – water (vapor) – has more cooling than heating effect – it is providing strong evaporation cooling of the surface and cloud shielding.

  15. Stephen Wilde (02:57:26)

    Looking at the data in ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/vostok/co2.txt it seems to me that at least 2000 years worth of CO2 is smoothed into each dated ice sample. The age of the ice is presumably dated with isotopes, counting annual layers in younger ice, looking for volcanic deposits, etc. So the age of the ice is fairly accurate.

    The age of the gas is based on a nonuniform diffusion of air through fresh snow and ice. From the data linked above this diffusion takes place for 1000’s of years. The bottom line is that any sudden natural variations in CO2 would be invisible in ice cores. That doesn’t mean that rapid natural variations in CO2 don’t exist, or do exist, but just that they won’t be visible in the ice core.

  16. Some plots taken straight from data no messing with timescales!
    Perhaps the dust is important?
    CO2 and temps seem to rise “simultaneously” at the end of an ice age.
    Note reverse time scales and the odd CO2 scaling to fit.

    0 to 40,000 years. GISP2 and EPICA temperatures plotted on this graph. Co2 steady rise is simultaneous with temperature @17500ybp
    note that only greenland gisp2 temperature shows a definite younger dryas – the antarctic EPICA data shows a flattening only.The EPICA CH4 data shows a misplaced drop around the younger dryas. Note the increased dust levels during the low temperature portion.

    40k to 100k years Note the dust levels are non zero during this period and high during the low temperature portion.

    100k to 200k years Co2 rises simulaneously with temperature @136kybp. Note the dust levels are high during the low temperature portion. CH4 termination of warm period

    Methane data is from:
    Loulergue, L., et al.. 2008.
    EPICA Dome C Ice Core 800KYr Methane Data.
    IGBP PAGES/World Data Center for Paleoclimatology
    Data Contribution Series # 2008-054.
    NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
    CO2 data is from
    0-22 kyr BP: Dome C (Monnin et al. 2001) measured at University of Bern
    22-393 kyr BP: Vostok (Petit et al. 1999; Pepin et al. 2001; Raynaud et al. 2005) measured at LGGE in Grenoble
    393-416 kyr BP: Dome C (Siegenthaler et al. 2005) measured at LGGE in Grenoble
    416-664 kyr BP: Dome C (Siegenthaler et al. 2005) measured at University of Bern
    664-800 kyr BP: Dome C (Luethi et al. (sub)) measured at University of Bern

    The age used is EDC3 and a comparison between dome fuji and vostok is here
    The EDC3 chronology for the EPICA Dome C ice core

    http://www.clim-past.net/3/485/2007/cp-3-485-2007.pdf

    Where did Fig 3 in the blog entry come from – its much too flat!

  17. Excellent but blindingly obvious research and well overdue.

    One point that hasn’t been made properly clear. If there is a strong feedback from temperature to CO2, then there can NOT be a strong feedback from CO2 to temperature. Two strong feedbacks would result in a runaway system rapidly going to either a snowball earth or Venus like atmosphere. The Vostok data shows clear periodicity / bistability which indicates strong feedback in one direction only, from temp to CO2.

    With regard to the different lags for rising and falling temperatures. When the temperature is rising, the CO2 in the sea becomes supersaturated and is blown off rapidly.

    When temperature is falling the sea becomes less than saturated in CO2, but the CO2 is recharged by less strong mechanisms of partial pressure balance at the surface, recharge by CO2 containing rainwater etc, this takes time to work.

    Hence the buildup of CO2 in the atmosphere from 3000 BCE as humans started slashing and burning forests at the dawn of the age of agriculture.

    Eventually the excess CO2 will be reabsorbed by the sea and be removed from the Carbon cycle as either carbonate or fossil fuel deposition, but as the Vostok data and Taylor’s paper show that it will take up to 8000 years for this process to take place.

  18. Why didn’t the author care about telling us how he constructed the temperatures in Figure 4? It really has nothing to do with all the known temperature reconstructions: http://co2.cms.udel.edu/images/ClimCh_image003.jpg

    The only thing it clearly shows is that the present CO2 rise is not due to increased temperatures. The only other thing it shows is that (if the linear fit is correct) temperature at time “t” will depend on both the CO2 value and the rate of change of CO2 at time “t”. Indeed, as “l” is much smaller than “t” itself, on can Taylor-develop CO2(t+l) (using some rescaling)

    CO2(t+l) = CO2(t) + l [dCO2/dt]_t + O(l^2)

    so that

    T(t) = CO2(t+l)/m – (b/m)
    = CO2(t)/m – (b/m) + (l/m) dCO2/dt
    = CO2(t)/10 – 27 + 5 dCO2/dt

    looks like a PD controller, right? Where CO2 would be the offset. So the author actually predicts that a change in CO2 should affect temperatures.

  19. The question was:
    ————–
    M. Simon (01:45:33) :
    Any suggestion as to why the rising lag is shorter than the falling lag?
    ————–
    .
    Not all processes are linear in reverse.
    .
    It likely has much to do with the chemistry of the water itself and the ability to absorb CO2 above a certain temperature, i.e., for how long and how low did the temperature have to be before atmospheric CO2 was absorbed?
    .
    Additionally one must observe how the atmospheric carbon was both absorbed and released by other sources.
    .
    Aside from the simplistic, what ~other~ external processes were involved which we don’t know about?

  20. “An alternative scenario is that CO2 is still stable and there is systematic error in the Vostok CO2 readings?”

    I think that’s a very large part of it. There’s no way to prove the ice core readings are accurate.

  21. Rhys Jaggar (00:15:00) :

    Not exactly Temp vs SSN, which is like comparing 10 burning twigs to 10 burning trees.
    Temp vs Solar Phenomenon Area Measurements is much better aligned:

    http://www.robertb.darkhorizons.org/DeepSolarMin6.htm

    Try the bottom graph, where the ratio of white-light faculae to penumbra associates with general temperature rise/fall.
    If the ratio of WLF/Pen is lower than 1, the temp falls.
    If it’s greater than 1, it rises.
    From 1976 onwards, nobody measures WLF, and the existing data is suspect as it is simulated, but I can speculate that it is greater than 1:1.

    What is needed?
    1.) Access to the unpolluted Temp data
    2.) Access to the Greenwich image collection to calibrate
    3.) an effort to measure the WLF post 1976 from images.

    Remember that WLF are the visible portion of the CaII K-line images, which are impossible to correlate to the latter.

  22. “Hence the buildup of CO2 in the atmosphere from 3000 BCE as humans started slashing and burning forests at the dawn of the age of agriculture.”

    How many gigatonnes of CO2 were humans producing 4000 years ago?
    Good thing it had no net effect on CO2 because it was recent biomass eh?

  23. I’ve just noticed. On Figure 1, time goes forward in the positive direction (to the right on the x-axis). On figure 2, time goes backward in the positive direction. Is it me or is this confusing?

  24. Juraj V. (03:53:01) :

    Maybe we should call this the “Swamp Cooler” effect.
    Very thoughtful. Thank you.

  25. I really enjoyed this one. Interesting to see CO2 begin to rise with the advent of human civilization or that period of time we call history. Maybe that’s the more important correlation, civilization -> CO2. Mighty big spike at the end there. Clearly it’s time to put the CO2 causedAGW hypothesis away.

  26. Sandy (06:28:52) :
    Early agriculture were mainly slash-and-burn, which is highly ineffecient. Big tracts of land in the middle east and in China were quickly deforested. In Denmark the major part of the transition from hunter-gatherers took only hundred years from 3900 BC.

  27. I am gratified by the responses. I think I should respond to a few:

    Rhys Jaggar (00:15:00) :

    I wondered whether ‘global temperature’ showed a lagged response to solar output intensity?

    Does anyone have any similar analyses about that??
    ————————————————–
    The original Vostok paper by Petit, et al. contains estimates of insolation.

    Tenuc (01:35:24) :

    I find Figure 4 chart very surprsing – if temperature didn’t cause the massive increase in CO2 which started around 2000 years ago, what did?
    __________________________________________________________
    Some approximate dates of the start of human activities that affected CO2
    6000 BC – agricultural revolution, with deforestation and exposure of soil
    3000 BC – bronze age, with smelting of copper and tin
    1000 BC – iron age, with smelting of iron oxides, best done with coal
    300 BC – roasting of carbonates for cement

    M. Simon (01:45:33) :

    Any suggestion as to why the rising lag is shorter than the falling lag?
    __________________________________________________________
    Some quick processes that put CO2 into the atmosphere are bacterial decomposition of organic material in soil, and thawing of frozen material. A slow process of absorption of CO2 by the surface is the formation of carbonaceous sediments, such as clathrate and coal.

    John A (02:37:33) :

    I question the linear assumption. As far as I can tell from theory the relationship between CO2 and temperature should be logarithmic.
    ______________________________________________________
    With data from complicated situations, one strategy is to look for the simplest possible relationship that fits, and then thinking about why. It tends to foster more discovery than looking for data that fit a given theory.

    Nick Stokes (03:31:08) :

    I don’t know why this is thought to be new. The IPCC Ar4 Sec 6.4.1 says

    The ice core record indicates that greenhouse gases co-varied with antarctic temperature over glacial-interglacial cycles, suggesting a close link between natural atmospheric greenhouse gas variations and temperature (Box 6.2). Variations in CO2 over the last 420 kyr broadly followed antarctic temperature, typically by several centuries to a millennium (Mudelsee, et al., 2002).

    followed by Fig 6.3, which has much the same information as the one here.
    _____________________________________________________
    The data are 10 years old, and Mudelsee’s analysis of lag is 8 years old. However, the IPCC did not conclude that temperature is independent of CO2.

    bill (04:12:39) :

    Some plots taken straight from data no messing with timescales!
    Perhaps the dust is important?
    CO2 and temps seem to rise “simultaneously” at the end of an ice age.
    Note reverse time scales and the odd CO2 scaling to fit.
    ______________________________________________________
    I like (i) seeing time progress from left to right and (ii) plotting things on similar scales when I am trying to see what kind of relationship they might have. I acknowledge that Petit, et al., Mudelsee and others plot with time progressing from right to left, etc., but maybe this is why they seemed to miss something simple but important.

    Pofarmer (06:05:42) :

    “An alternative scenario is that CO2 is still stable and there is systematic error in the Vostok CO2 readings?”

    I think that’s a very large part of it. There’s no way to prove the ice core readings are accurate.
    ____________________________________________________
    I’d be happy to use a more comprehensive data set with better resolution, but I don’t know of any.

    Jimmy Haigh (06:29:00) :

    I’ve just noticed. On Figure 1, time goes forward in the positive direction (to the right on the x-axis). On figure 2, time goes backward in the positive direction. Is it me or is this confusing?
    _____________________________________________
    On figure 2, time progresses from left to right. The model runs for a 500,000 year interval in that is meant to be like the Vostok interval, but there is no correspondence between dates.

  28. Well you can find the same information in climate guru Al Gore’s book on pages 66/67 Temperature changes precede CO2 changes; even Al thinks it does; and just as the lamb drinking downstream is not the source of the muddy water the wolf is wallowing in upstream; so too the CO2 is not the cause of the previous temperature change. QED

    Talk about obfuscation The paper says that fig 2 is rescaled from Hogg’s fig2a; fair enough; so why didn’t this author also rescale the temperature scale to match the fig 1 time scale (as to origin). And in fig 4, why does the author pick 3000 years ago as the point of departure for the CO2 wander, rather than the much more obvious 2000 years ago.

    And thank you very much but I’m quite happy with BC and AD; or even the more logical BP; so spare me the Before Christian Era (BCE) and Christian Era (CE) silliness.

    Don’t tell me; they have some other dumb politically correct time scale.

    Hey since the paper is in English; and not Arabic or Korean; why not use BC and AD that all English speaking peoples understand, or simply BP if you want to make today the time origin.

    Haven’t quite figured out what this paper adds; to me it was always self evident (if you believe the ice core methodology) that the CO2 doesn’t cause the Temp changes.

    At least with this paper, I expect the graphs are drawn more accurately than are the artist’s renditions in Fat Albert’s silly book.

  29. Nogw (08:09:31) :

    Can´t believe green house effect doesn´t exist at all! Wow!
    __________________________________________________
    There seems to be no clear evidence of it for CO2, but the analysis doesn’t cover water vapor, CH4, etc.

  30. Thank you R Taylor for your interesting work.

    I spent time looking at the issues of CO2 possibly amplifying temperature, from evidence of ice core records, and came to the conclusion that the science was a clear “NO” but AGW folk still regularly point to RealClimate “information” that leads back to a paper which supposedly suggests CO” amplifying temperature change, but when I looked, it clearly does not. The essentials of all this I encapsulated in the relevant sections of my Primer (click my name).

    Frank Lansner wrote a very interesting piece on this, here at WUWT a while back.

    George White has done work I regard as excellent, CO2 Forcing: Fact or Fiction – it’s well worth a read and deserves space here some time IMO.

    Personally, from my studies of Jaworowski and Segalstad, both ice core experts, I feel strongly that the measurements of CO2 in ice core are not foolproof, and that CO2 leaks out progressively, either during the 80 or so years of firnification or during scientific extraction of the ice core that is under increasing pressure at increasing depth and contains clathrates. But Ferdinand Engelbeen always challenges me at this point, and I have not mastered enough understanding nor contacted Tom Segalstad to answer the issue. Of course, showing the carbon dioxide hockey stick to be based on bad science / bad technology of ice core measurements would be a HUGE nail in the AGW coffin.

  31. Flanagan (05:01:29) :

    Why didn’t the author care about telling us how he constructed the temperatures in Figure 4? It really has nothing to do with all the known temperature reconstructions: http://co2.cms.udel.edu/images/ClimCh_image003.jpg

    The only thing it clearly shows is that the present CO2 rise is not due to increased temperatures. The only other thing it shows is that (if the linear fit is correct) temperature at time “t” will depend on both the CO2 value and the rate of change of CO2 at time “t”. Indeed, as “l” is much smaller than “t” itself, on can Taylor-develop CO2(t+l) (using some rescaling)

    CO2(t+l) = CO2(t) + l [dCO2/dt]_t + O(l^2)

    so that

    T(t) = CO2(t+l)/m – (b/m)
    = CO2(t)/m – (b/m) + (l/m) dCO2/dt
    = CO2(t)/10 – 27 + 5 dCO2/dt

    looks like a PD controller, right? Where CO2 would be the offset. So the author actually predicts that a change in CO2 should affect temperatures.
    ———————————————–
    The temperatures are directly from the online Vostok data (http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html). I did not average them in groups of 10, because the time-scale is detailed enough for clarity.

    I don’t think your additions to the model will make it fit any better, so I would avoid them as superfluous.

  32. Taylor,

    I would love to see a similiar analysis for the Northern Hemisphere. Maybe GISP2? Not enough cycles probably, but it would interesting to see the CO2, dust levels and temperatures for the Northern Hemisphere!

    Somethings fishy there, if you process the CO2 file for GISP2. The levels are too high when the temperature is low, the temperature swings are larger in the northern hemisphere. And, for some strange reason, there is no CO2 data in the file that correlates to the interglacial period, where one would assume we would sure want to know the levels for comparison to present atmospheric measurements.

    Ever process the data? Correct depth to age, would be interesting to discuss…

    Ed

  33. Dear r taylor,

    what I meant to say is that your “linear” fitting is actually the equation of a proportional-differential feedback – which answers your question (feedback or equilibrium?)

  34. I’m not sure what you are showing here. Yeah, we know that the temperature change leads the CO2 change, but the question is to what extent that amplifies the warming/cooling from whatever started the change.

  35. Among other things Taylors excellent graphs demonstrate a point I tried to make in a previous post.

    The whole greenhouse gas concept is based on the idea that changes in greenhouse gas concentrations alter the radiation balance.

    The variable that betrays a radiation imbalance is not temperature but the rate of change of temperature. If there is a positive imbalance (more being received than radiated into space) the temperature will rise until the balance is restored. If there is a negative imbalance the temperature will fall to compensate.

    It does not take a mathematical genius to see that the rate of change in temperature is highly correlated with the level of CO2. Unfortunately. not only is it delayed, but the correlation is negative. Every period of rapid warming has occured when CO2 has been low and every period of rapid cooling has occured when CO2 has been high.

    Either CO2 is an irrelevant dependent variable or it is contributing to cooling. It is obviously not acting like the AGW models suggest.

    It is very clear that something very powerful is able to lift the world out of its normal frozen state. These brief periods of extreme warmth only last for about 20,000 years at the most. Our current warm period undoubtedly allowed the rise of modern civilisation about 10,000 years ago. How long have we got before it starts to cool again?

    I only wish AGW was real because it might have been our only hope!

  36. Pofarmer (06:05:42) :

    “An alternative scenario is that CO2 is still stable and there is systematic error in the Vostok CO2 readings?”

    I think that’s a very large part of it. There’s no way to prove the ice core readings are accurate.
    ____________________________________________________
    I’d be happy to use a more comprehensive data set with better resolution, but I don’t know of any.

    I’m not criticising your work. I conclusions drawn on the ice core data are suspect. I’ve looked fairly hard for “proofs” for the numbers in the ice core data, and have yet to come across any.

  37. I’d like to add my thanks to Johnny Honda for his excellent link: click

    We routinely hear of retired scientists abandoning the alarmist CO2=AGW conjecture and accepting the fact that natural climate variability completely explains the current climate.

    But show us any retired climatologist, meteorologist, etc., who was a skeptic until recently — but who now believes in the alarmists’ CO2=AGW conjecture.

    As soon as these folks can speak freely, without jeopardizing their employment or their next pay raise, they become outspoken about their skepticism.

  38. M. Simon (01:45:33) :

    “Any suggestion as to why the rising lag is shorter than the falling lag?”

    I would suggest that out-gassing occurs throughout the volume of heated water (oceans), while re-absorption on cooling occurs at the surface.

  39. Cyclical outgassing of CO2 may be a necessary part of the cycle of flora and fauna rise and fall that we see in so many species. Why is it that humans are always thinking that meddling with mother nature, when it does not go their way, is a GOOD thing??????

  40. cal (14:06:27) :

    Among other things Taylors excellent graphs demonstrate a point I tried to make in a previous post.

    The whole greenhouse gas concept is based on the idea that changes in greenhouse gas concentrations alter the radiation balance.

    The variable that betrays a radiation imbalance is not temperature but the rate of change of temperature. If there is a positive imbalance (more being received than radiated into space) the temperature will rise until the balance is restored. If there is a negative imbalance the temperature will fall to compensate.

    It does not take a mathematical genius to see that the rate of change in temperature is highly correlated with the level of CO2. Unfortunately. not only is it delayed, but the correlation is negative. Every period of rapid warming has occured when CO2 has been low and every period of rapid cooling has occured when CO2 has been high.

    Either CO2 is an irrelevant dependent variable or it is contributing to cooling. It is obviously not acting like the AGW models suggest.

    It is very clear that something very powerful is able to lift the world out of its normal frozen state. These brief periods of extreme warmth only last for about 20,000 years at the most. Our current warm period undoubtedly allowed the rise of modern civilisation about 10,000 years ago. How long have we got before it starts to cool again?

    I only wish AGW was real because it might have been our only hope!
    ________________________________________
    Interesting observation about rate of change. Regarding CO2 and cooling, we do know that CO2 is essential to photosynthesis, which is endothermic and ultimately responsible for the huge amount of energy stored in carbonaceous sediments. However, we also know that it has radiative properties. In any event, the net effect of all we know and don’t know seems to be equilibrium with temperature.

    I wouldn’t despair about the next ice age. The apparent stability of temperature over the last 11,000 years seems to be unprecedented and, while arrogance is so human, we might have had something to do with it. In our fascination with AGW we have identified some gases with powerful radiative effects that do not seem to be in self-balancing systems. If we are faced with encroaching continental ice-sheets and hard winters into the tropics, I expect we will geoengineer with gases or in some other way.

  41. “The most recent CO2 determination from the ice-core has a date of about 340 BCE. We can add an early-industrial-era value of 290 ppm at 1800 CE ”

    So the line you drew from 340 BCE to 1800 CE was determined by what? It could have been much flatter and then turned up suddenly as in a logarithmic display. Then there is no need to find out why CO2 was so high 5000 years ago, but why it may have accelerated around 1800 CE, which conveniently matches with the industrial revolution.

  42. Get it published, excellent stuff. I think many here have long been aware that outgassing of Co2 is a natural process following a rise in T and this supports that position.

    I understand the Vostock ice core came from the Antarctic, I would imagine this part of the globe would not show the MWP or LIA due to the large ocean cover in the southern hemisphere and the antarctics self sustaining climate.

    I would excercise care though when comparing modern Mauna Loa values with Vostock values, as they cannot be compared. One value is from a cold environment where levels are low due to absorbtion and the other is in an area where the sea would be outgassing Co2 due to warmer SST.

    Hence they cannot be compared (though they often are to suggest current Co2 levels are unsual). However, excellent work!

  43. Justin Sane (20:53:59) :

    “The most recent CO2 determination from the ice-core has a date of about 340 BCE. We can add an early-industrial-era value of 290 ppm at 1800 CE ”

    So the line you drew from 340 BCE to 1800 CE was determined by what? It could have been much flatter and then turned up suddenly as in a logarithmic display. Then there is no need to find out why CO2 was so high 5000 years ago, but why it may have accelerated around 1800 CE, which conveniently matches with the industrial revolution.
    ______________________________________________
    The equilibrium model indicates that about 8000 years are required for CO2 to decline in response to a drop in temperature. There might have been a trivial decline in temperature between 340 BC and 1800 AD, so there is no reason to think that temperature caused a significant decline in CO2 during that interval. Between those dates, however, the Romans paved and cemented their way through much of Europe and the middle-East, the Silk Road was established to China, where the Hans were building a very long wall, Islam spread from Spain to Indonesia, Russia emerged as an organized state, the Incas, Mayas and Aztecs built empires, global trade commenced and intensive agriculture spread to the Americas. All of these things might have shaken a little more CO2 loose from the soil.

  44. stumpy (22:49:55) :

    Get it published, excellent stuff. I think many here have long been aware that outgassing of Co2 is a natural process following a rise in T and this supports that position.

    I understand the Vostock ice core came from the Antarctic, I would imagine this part of the globe would not show the MWP or LIA due to the large ocean cover in the southern hemisphere and the antarctics self sustaining climate.

    I would excercise care though when comparing modern Mauna Loa values with Vostock values, as they cannot be compared. One value is from a cold environment where levels are low due to absorbtion and the other is in an area where the sea would be outgassing Co2 due to warmer SST.

    Hence they cannot be compared (though they often are to suggest current Co2 levels are unsual). However, excellent work!
    —————————————-
    Thanks. Modern CO2 measurements in Antarctica (http://cdiac.ornl.gov/trends/co2/csiro/csiro-spo.html) do seem comparable to those at Mauna Loa.

  45. Comparing ice cores with instrument measurements makes no sense. If you smooth the instrument measurements with a 1000+ year running average, then it could begin to make sense. Why, in the ftp link I posted above, is the CO2 in 4050 year old ice only 1700 years old???

  46. Eric (skeptic) (08:13:46) :

    Comparing ice cores with instrument measurements makes no sense. If you smooth the instrument measurements with a 1000+ year running average, then it could begin to make sense. Why, in the ftp link I posted above, is the CO2 in 4050 year old ice only 1700 years old???
    _________________________________________________________
    We seem to be looking at different data sets. From the Vostok home page, http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html, If you go to the CO2 page http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_co2.html, your data set seems to be the second one listed, referenced to 1987. I used the first data set, referenced to 1999, that seems to be more extensive. All the temperature data I used is from the isotope/temperature page, http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_isotope.html.

  47. My guess would be that the level of CO2 trapped in ice in Antarctica is a
    measure of the level of CO2 dissolved in the ice at several thousand feet that eventually falls as snow. Since the partial pressure is lower at this altitude I would expect the disolved gases to be less. It may well be that this correlates with CO2 measurements made on the surface but I doubt they are the same. Does anyone know it how this works in practice?

  48. BCE is before common era and CE is common era. I assume to render the current dating system non christian.

  49. The original papers cited on the Vostok on-line pages give some description regarding technique. I have taken the numbers as they are, as I have great respect for the science that went into their derivation. It seems some of the conclusions in the papers were flawed by viewing the numbers through the lens of faulty assumptions.

  50. Kent Gatewood (10:05:41) :

    BCE is before common era and CE is common era. I assume to render the current dating system non christian.
    ————————————
    Yes. While the terms might sound stilted to those accustomed to BC and AD, I think BCE and CE are specified in most style guides for scientific discussion.

  51. “”” Kent Gatewood (10:05:41) :

    BCE is before common era and CE is common era. I assume to render the current dating system non christian. “””

    Total political BS; what is “common” about the CE; and just when is To on the CE time scale ?

    BP serves the purpose of establishing a time, and a time that is independent of when mohammad fell into a well or whatever.

    The Chinese get along just fine without using our calendar or raising a stink about it. This CE/BCE silliness is just a creation of the loony left who want to eliminate human beings and their foibles from the account of history.

  52. R Taylor (08:54:02)
    Thanks for the link. Yes the 1999 data set is newer, but it leaves out some important information, namely that the CO2 in ice is 1000’s of years younger than the ice. That fact is critical to understanding that the CO2 readings are smoothed by a unknown multi-1000 year distribution. If there is another explanation for the dating difference other than smoothing by gas diffusion through snow and less dense ice I would like to hear about it.

    With the smoothing hypothesis there is no way to know if spikes with a duration of a few hundred years or less (like the current spike) can occur naturally by simply looking at the ice core readings.

  53. No, but I just had a look again at the Mauna Loa CO2 record around the time of the Gulf War. The “Fires of Kuwait” might have added a few ppm during the first half of 1991, but whatever might be there is small compared to the seasonal variation.

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