A Few Things Ill Considered

A layman's take on the science of Global Warming featuring a guide on How to Talk to a Climate Sceptic.

Thursday, February 02, 2006

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CO2 Lags Not Leads

(Part of the How to Talk to a Climate Sceptic guide)

This article has moved to ScienceBlogs

It has also been updated and this page is still here only to preserve the original comment thread. Please visit A Few Things Ill Considered there. You may also like to view Painting With Water, Coby Beck's original fine art photography.



  • At March 14, 2006 5:34 AM, Anonymous Anonymous said…

    Thanks for all your efforts to "set the record straight" - a great idea and much needed. My own examination of the warming we see at present seems to indicate that the atmospheric CO2 rose first (beginning with the industrial revolution and the massive use of fossil fuels) and this has been followed by the rising global mean temperature. That is, the opposite sequence of events to what the ice core records indicate for interglacial periods of the past 650k years. If so, this would further the argument that humans have impacted the global climate. Am I wrong about this? C. W. Dingman

  • At March 14, 2006 2:37 PM, Blogger coby said…

    No, I don't think you are wrong that this is further indication of an anthropogenic "fingerprint". But I have even seen some try to suggest that CO2 is rising now as a response the MWP, similar to the time lag of the ice core records. This is pretty lame as the CO2 in the atmosphere is clearly unnatural and the response is an order of magnitude greater than what the MWP might cause if it were the same mechanism as in the glacial periods. That is to say that we have seen 100ppm CO2 rise for *maybe* one degree warming in the MWP whereas the ~100ppm CO2 response in the glacial periods was in response to a rise of 10oC.

  • At April 06, 2006 5:38 AM, Anonymous Anonymous said…

    If increased atmospheric CO2 causes increased global ground temperature, I would at least expect some incidents in the ice core records where a significant rise in CO2 was the initial cause of a significant temperature rise. Has that ever happened, or has there always been a 600-1000 year CO2 rise lag?

  • At April 06, 2006 8:11 AM, Blogger coby said…

    There needs to be a mechanism whereby atmospheric CO2 is increased. AFAIU during the glacial cycles the only mechanisms proposed for this are reactions to rising temperatures.

    There are however other examples in geological history of GHG driven warming, some better understood and more certain than others. Read about the PETM, or the formation of the deccan traps.

    Also the hypotheses surrounding Snowball Earth rely on GHG warming to eventually escape that condition. I do not know how much evidence there is for this so that may not be support for GHG driven warming rather it comes out of that theory.

  • At April 25, 2006 6:17 AM, Anonymous Anonymous said…

    It is very easy to realise, these 'ice cores' provide NO 'data' for the production of 'valid inference' in the manner attempted in support of the 'greenhouse concepts'.

    To reprise the numbers again:-
    The atmosphere is contained in a volume of ~51,472,901,235 cubic km's.
    The mass of the atmosphere is regarded as ~0.0000051 x10^24 kilograms.
    The mass is NOT distributed uniformly within the volume represented (with an assumed depth of the atmosphere being 100 km's.

    So, those few millilitres (or even grams) of 'gas' regarded from within the 'bubbles' is INFACT a statistically insignificant, and as such uncorrelated, population sample.

    As such there is nothing that can be VALIDLY claimed regarding the Atmosphere from regard to the contents of these bubbles. The issue is that it IS that any 'gas characteristics' found within these bubbles can only be validly considered to BE "some random or chaotic value". That is the reality the situation presents over 650,000 years ESPECIALLY.

    Gas within the snow will be squeezed laterally and vertically out of the snow as it settles upon a base that is already hard, having undergone the same processes. It is the loss of gases that allows the 'snow to settle' and the 'gas' will be in constant 'flow' vertically and laterally.

    Again it is methodology that is the issue, and again rather than use the validated procedures of SCIENCE, opinion is being produced to garner a veneer of 'correctness'.

    'Consensus' is NOT producing validated methodology in SCIENCE within the 'practices' of 'climate science'.

    Your's, Peter K. Anderson a.k.a. Hartlod(tm)
    From the PC of Peter K Anderson
    E-Mail: Hartlod@bigpond.com

  • At May 23, 2006 9:49 PM, Anonymous Anonymous said…

    I'm not sure what you are trying to accomplish with your argument, Peter, for or against Global Warming, but all you manage to do is make the question a moot point, at most... which is exactly what the answer already does....

    Also, why are there 'so many' apostrophies and capitalized WORDS?

    The atmosphere is very large. It is thick at the bottom and thin at the top. Hopefully everyone can agree on that. We also know where most of the CO2 goes... to the top. However, a lot of it sticks around here down on the ground too, you know. Its kinda where the CO2 comes from. So if there was less CO2 on ground level to get trapped in the ice a long time ago, then the CO2 in the air was also at lower levels. The few milliliters of 'gas' is not a 'statistical anomoly', its a random sample of the gas that was in the air at the time. Its not like the ice said "Hmm, I'm not going to take those CO2 molecules, they are nasty."

    I... dont even know where you are going with the description of how air is trapped in ice. Yeah, its pretty much correct, but it doesnt prove anything...

  • At May 24, 2006 9:37 AM, Blogger coby said…

    Hi urthen,

    It is actually not even a question of random samples or statistics. CO2 is well mixed throughout the atmosphere, as you get really high things do change but certainly in the troposphere you do not need to be concerned about sample sizes etc. CO2 will be anomalous near sources and terestrial sinks but this is not a concern in the middle of a huge ice sheet, unless there was an active volcanic vent nearby. One bubble of air will show the same mix of gases as any other from the same time period. This is confirmed by the measured agreement between all the different cores from around Antarctica and Greenland.

    I have explained this to Peter Hartlod before, but he has his own unique scienctific theories that are in sharp constrast to the rest of the world and empirical evidence. Oh well.

    I recently came across a link to the wikipedia article on ice cores, it is an excellent article!

  • At May 27, 2006 8:01 PM, Blogger Peter K. Anderson said…

    The issue is relatively easy to understand, and to brush past the inane and vapid criticisms however....

    There is nothing at all to validate that CO2 simply goes to the top of the atmosphere. There is no selective gravitational process that promotes CO2. The only molecule that is constrained outside of gravitational effects is H2O, limited by its condensation and ice points. So infact the comment is made that regarding the RELATIVE proportion of H2O and CO2 within the gravitational stratification of the atmosphere.

    You will notice also that O2 is produced solely at ground level. It is that O2 needs to be elevated against gravity, infact all molecules do. This elevation is produced by the addition of KINETIC ENERGY into the atmosphere at the base of the atmosphere. Here the production of Turbulence, by the processes of Conduction and Convection, introduce into the gas of the Atmosphere the energy, expressed as the kinetic velocity of the molecular unit, to allow motion in resistance of gravity.

    It is the median kinetic velocity that is measured as Temperature, but that kinetic energy being used to support the atmosphere against gravity is NOT available for measure as Temperature.

    However, it is that the few millilitres of gas in ice cores is NOT a sample whose 'behavior' can be correlated to a population, these 'samples' are STATISTICALLY insignificant as a 'population sample', it is NOT enough to simply say it is a 'random sample', perhaps these STATISTICAL processes and 'Experimental Design' analysis concepts should be what you need to read urther, rather than 'climate opinion' (said without trying to appear over critical).

    Again and also with the situation of how Gas is RELEASED within settling snow, there is NOT a controlled mix, so these 'random samples' mentioned are also NOT validly datable, as well as presenting a STATISTICALLY insignificant view of the POPULATION of molecules that is the Atmosphere to compound the Error situation.

    It is not at all STATISTICALLY significant that there IS any difference tween ice cores Coby, which is the point I make. It is not that any claim towards the 'Population' can be made from these 'samples' including any notice of 'anomalies'; it is that the ice core samples CANNOT actually STATISTICALLY show any 'Population correlation', so be indicative OF a 'Population behavior'.

    This is all well KNOWN (common knowledge) principles of (perhaps advanced) Statistical Analysis, you simply need to read SCIENCE rather than noticing 'climate opinion', and is not at all a ["unique scientific theory'"] of my own Coby.

    Perhaps if polite questions where asked rather than 'tag team' ridicule and belittlement, or presentation of misplaced accliam for wikipedia 'articles'...

    Your's, Peter K. Anderson a.k.a. Hartlod(tm)
    From the PC of Peter K Anderson
    E-Mail: Hartlod@bigpond.com

  • At October 28, 2006 10:52 AM, Anonymous Anonymous said…

    As there have been no commentaries for a long time, I think this commentary by Arthur Rorsch applies (told in a debate on CO2):

    I attended today an informal meeting of geologists (and paleobiologists) of alumni of my old university in Delft, on the interpretation of current data on climate change.(ice cores, proxies) My feeling is that in this scientific circle the idea that CO2 concentrations would significantly contribute to change of the greenhouse effect, is a passed station. And it is replaced by the thesis, CO2 changes, follow temperature changes, not the reverse. But that is not the end op the story.

    Temperature is still only one indicator of climate change. In a state-phase diagram CO2 flux=f(T) the coincidence is only just above significant (R2=0.5). This coincidence is still higher than T=f(CO2 concentration) (R2=0.05), or CO2 flux=f(CO2 human emission) (R2=0.3). I think we still have to search for changes in other meteorological conditions to explain de remarkable rise 280-380.

    That is why I became interested in the General and global circulation of the air masses that carry CO2. William Kinnimonth. brought to my attention a paper by Tenbreth and Caron (2001) , which may be helpful to quantify CO2 circulation. (I still have to read it, I have no direct assess to the reference) But most probably it will not reveal the changes that have been taken place in the air circulation over the last decades.

    So far Leroux (and the thesis of Pommier) is my only source. (There are of course other studies on the North Atlantic oscillation, but most of it is computer simulation interpretation. That I am discussing critically with a project leader in our meteorological institute KNMI)

    I think, the major problem is still the interpretation of the change of 13C/12C ratio in the atmosphere. It’s decline indicates for sure that human emissions remain in the atmosphere. (And that is no wonder) I think it is an important tracer to learn more about CO2 circulation. But the interpretation of the data depends strongly on the circulation model one has in mind.

    Herewith I especially invite others to present interpretations of the 13C/12C ratio change. (I consider the after Stockholm discussion unsatisfactory).

    Kind regards,

    Arthur Rorsch,
    The Netherlands.

  • At October 28, 2006 11:15 AM, Blogger coby said…

    My feeling is that in this scientific circle the idea that CO2 concentrations would significantly contribute to change of the greenhouse effect, is a passed station. And it is replaced by the thesis, CO2 changes, follow temperature changes, not the reverse.

    As one of the main points of this post lays out, it is not an either/or proposition. There is no serious scientific challenge to the theory that elevating CO2 will enhance the Greenhouse Effect. It is in fact quite hard to imagein that this could not be so.

    I think, the major problem is still the interpretation of the change of 13C/12C ratio in the atmosphere. It’s decline indicates for sure that human emissions remain in the atmosphere. (And that is no wonder) I think it is an important tracer to learn more about CO2 circulation. But the interpretation of the data depends strongly on the circulation model one has in mind.

    Have a look here:
    and in particular follow the link near the bottom to the RealClimate discussion.

  • At October 31, 2006 11:58 AM, Anonymous Anonymous said…

    Can you or any of your contacts respond to this?

    The author challenges Gavin Schmidt by name and I believe you are in communication with him.

  • At November 07, 2006 9:34 AM, Anonymous Anonymous said…

    Here is another version of the temperature and CO2 plot you reference, though it does not include CH4 and the time axis is reversed:
    Note that the correlation is not so tight, and a definite lag is apparent. In most cases, temperature spikes, and after a lag, CO2 spikes. If CO2 is forcing temperature after the "initial warming", wouldn't another spike in temperature be expected in response to an increase in CO2? In most cases temperature changes without any apparent influence from the CO2 concentration. Note the spikes at about 340,000 bp. In this example temperature spikes and falls quickly, continuing to fall through the lagging CO2 spike. This is repeated over and over again, suggesting that CO2 is behaving most of the time in a feedback manner.
    Lacking additional evidence, wouldn't it be more logical to assume that whatever caused the initial temperature rise continued to sustain it, and CO2 reacts to temperature because of decreased solubility in ocean water with rising temperature?

  • At November 07, 2006 1:15 PM, Blogger coby said…

    Hi whit, thanks for the comment.

    I hae two responses, first is that there is still alot of controversy about the precise dating in these records. The age of the ice vs the age of the CO2 sample is not that well understood, at least so so well that the kind of detail you are examining should be too heavily relied on. The second is that we are not just dealing with arbitrary data devoid of physical processes. There is no theory of atmospheric chemistry whereby increasing CO2 in the amounts and ranges relevant here does not result in a positive forcing. So I would suggest that if something does indeed seem wrong about this record (though I don't agree with your reading of it) then it is probably more likely that the dating is not quite right and/or there are other factors involved about which we have no record.

    You might be interested in this post as well.

  • At November 11, 2006 2:50 PM, Anonymous Anonymous said…

    Well, nothing beats going to the original data. I obtained CO2 and temperature proxy data from links on this website http://www.daviesand.com/Choices/Precautionary_Planning/New_Data/index.html and did a little plotting of my own. http://webpages.charter.net/wtelle/Warming/Vostok.jpg These are data from the Vostok ice core, units not implied on the y-axis because the scales have been normalized to track changes.

    Not only does CO2 seem to lag temperature movements, but there are several events, which I call CO2 "shadows", where CO2 continues at high levels for extended periods while temperature falls to near epochal minima. The one preceding the Wisconsinan glacial lasted roughly 7000 years and the one preceding the Illinoian glacial lasted roughly 5000 years. I think their duration would override any potential "dating [that] is not quite right".

    Also on that topic, if the dating of these data is "not quite right" one would expect it to be random rather than systematic. If, in reality, both T and CO2 track together, we would see just as many CO2 leads as lags, and, if CO2 leads T, there would be more CO2 leads. That's just not the case; while a couple of minor cases may suggest CO2 leads, many major and quite obvious ones point to its lag.

    I quite agree with you that "there are other factors involved about which we have no record." That is exactly why these hopelessly complex computer models cannot work when all of the variables aren't even known. It appears to me that one or more of them are forcing temperature, which is in turn forcing CO2.

    Your assertion that "There is no theory of atmospheric chemistry whereby increasing CO2 in the amounts and ranges relevant here does not result in a positive forcing." is not entirely correct. A hypothesis proposes that there already is far more than enough C02 in the atmosphere for absorption to extinction, and adding more only causes extinction to occur when infrared radiation passes though a few less meters of atmosphere. I have not yet had time to research this hypothesis, more later.

    Best regards to all.

  • At November 11, 2006 8:12 PM, Blogger coby said…

    if the dating of these data is "not quite right" one would expect it to be random rather than systematic.

    Why? Random errors are random, systematic errors are systematic. In particular, there are alot of complications in determining the age of the air sample relative to the age of the ice it is in, due to precisely when the ice seals off and becomes non-porous. A mistake in this correction might result in all ages being ~400yrs to low for example. Or maybe the process is different in an amount that is a function of average temperature, etc

    If, in reality, both T and CO2 track together, we would see just as many CO2 leads as lags, and, if CO2 leads T, there would be more CO2 leads. That's just not the case; while a couple of minor cases may suggest CO2 leads, many major and quite obvious ones point to its lag.

    Who is arguing otherwise? In this record, temperature changes appear to lead CO2 changes. There is no known mechanism taking place over this period whereby CO2 rises in the atmosphere on its own, it does so in response to warming.

    I quite agree with you that "there are other factors involved about which we have no record." That is exactly why these hopelessly complex computer models cannot work when all of the variables aren't even known. It appears to me that one or more of them are forcing temperature, which is in turn forcing CO2.

    Why does it matter in the context of global warming policy if computer models can not definitively explain the distant past? The variables today are much better constrained and there is no great mystery, though many interesting details are still being hashed out.

  • At December 06, 2006 6:36 PM, Anonymous Anonymous said…

    You asked: Why does it matter in the context of global warming policy if computer models can not definitively explain the distant past? The variables today are much better constrained and there is no great mystery, though many interesting details are still being hashed out.

    Of course, it doesn't matter, if you've decided you believe in GW because it gives you an overarching reason to accomplish what your heart desires to begin with... i.e. reducing the human impact on the planet... If what you want is an excuse to control all of mankind and how we as a species continue to grow (or not) in the future... then it really doesn't matter if the model can relate to historical data or not... only that they can scare the crap out of you now...
    If on the other hand you really want to know the truth of what is really happening, trusting models at all should scare you...
    For all those out there pushing, pushing, pushing for policy change... You should be careful when you say that uncertainty doesn't justify not taking action. You should be careful what you ask for...
    What if all those "let's do it types" get ahead of you? (and they will...) No one ever maintains control of an issue through to the end, esp. in the minds of the masses or politicians...


    What if a politician decides to take action because whatever the consequences to the earth, he'll get elected next term because fixing the environment is really becoming popular? (and he or she really believes that this will work...;o)
    What happens if we become zealously proactive? What if "engineers" start trying to actively "cool" the globe? And don't say awe that can't happen... too many historical examples of that being proven wrong...

    We could spray reflecting debris in the upper atmosphere (like a volcano)... but how much does it take and what if something like a real volcanic event occurs...afterwards? Or God forbid, the crazy guy in Iran tries to bring back the 12th Imam by a mushroom cloud (his stated intension...)

    What happens if we leap in, but can't stop falling mid leap even if we find out we shouldn't have? You know that sick feeling you get when you've lept off the diving board and you know you aren't going to be able to avoid that painful belly flop? (maybe most of you are too cool to remember that sort of moment...but think of something equally bad like the time you accidentally set something on fire and it started getting out of control...) I think it will be worse than that...

    Seems like to me we need to be much, much, more certain before we go making policy all over the earth that could actually harm us... or maybe not quite so bad, but really not desirable, harm many developing countries and distract them from addressing real environmental land use and energy production problems that would actually help the environment and save human lives now, today... but keep an eye on the future... not suggesting head in the sand stuff... just let's stop the panic... if you have to panic it's probly too late... most people don't behave terribly rationally while panicing...

  • At December 22, 2006 6:00 PM, Anonymous Anonymous said…

    This blog entry is an excellent example of a post and comment thread gone horribly wrong - a failed lesson in "How to Talk to a Climate Sceptic".

    If anything, what this thread highlights is the degree to which there is uncertainty in the science around global warming. Of course this really shouldn't surprise any reasonable person. In a science as young and complex as climatatology such uncertainty is to be expected. In fact, any broad consensus in climatology at this early stage should be viewed with extreme suspicion. What counts is the quality of the science - provable (and falsifiable) theory backed up by hard data. Consensus is essentially irrelevant.

    Unfortunately, climate change has become a thoroughly politicized subject. With the likes of Al Gore running around in a near panic, pushing his awful Chicken Little film, honest scientific debate on the subject has become all but impossible.

    I agree wholeheartedly with the previous anonymous commenter.

  • At January 22, 2007 12:59 PM, Anonymous Anonymous said…

    My concern with the time lag is not the initiation of warming, but the onset of cooling while CO2 is still at a peak. Clearly some other factor is driving the initiation of the warming event (if not a large portion of the entire event), and also the initiation of the cooling event. If we can find what triggers the cooling irrespective of high CO2 levels, that could provide a solution to our current 'problem'.

    Perhaps I am completely ignorant, or blinded by common sense, but generally if a change in variable A (CO2 concentration) follows after variable B (temperature), the simplest explanation is that A may be causing B. Again, there may be a host of other interactive effects between the two, but I believe that the burden of proof is on those who would use this historic correlation to advocate B causes A.
    The data seems to very clearly show that past temperature increases are followed by CO2 increases (which makes logical sense from my rudimentary understanding of CO2 solubility in water). Further it seems clear that temperature decreases are followed predictably by CO2 decreases (again very logical).

    I do not dispute the fact that elevated levels of CO2 should cause elevated temperature, in a closed system.

    I do question why we are not looking to find the drivers that seem to have historically overpowered the greenhouse effect of CO2.

  • At January 22, 2007 1:57 PM, Blogger coby said…

    Hi Bob,

    Thanks for the intelligent comments. I will confess upfront that my understanding of the details is sketchy, but the best hypothesis is currently orbital forcing. This is for both the warming events and the cooling events (much slower, BTW). Don't forget that a stable though elevated CO2 level will not cause any trend, forcing stops when a new equilibrium is reached. Thus there is not really any sense in thinking of GH effect being "overwhelmed" by anything.

    You are absolutely right that this data strongly suggests that A (temp changes) causes B (CO2 changes). There is however, absolutely no evidence in that fact that B can not also cause A. The laws of physics (radiative properties of GH gases) tell us we should in fact *expect* that B causes A. The data is in fact also consistent with this expectation, because all the time CO2 is rising or falling significantly temperature is as well.

    So how much of the temperature swings are orbitally forced and how much GHG forced and how much ice sheet albedo forced? Unfortunately there is no other path to an answer for this than through a GCM. GCM experiments indicate that approx 1/2 of the warming and cooling is the result of rising and falling CO2 (and CH4 and NO2).

    Now into the sketchy areas, the initiation of the cooling events is indeed consistent with orbital cycles, but there are a lot of uncertainties in the details and among them are some controversies about the accuracy of dating, specifically the relative timing of changes in temp proxies and CO2. I don't believe the models are able to satisfactorily reproduce what the history seems to have been. They do well for the warming, but not the cooling.

    This is not necessarily all the fault of incomplete models, there are a lot of climate factors to try to reconstruct and data is not always well resolved and precise.

    In short, there is no demonstrable contradiction in these ice core records of today's understanding of the climate system and there is no theory out there anywhere (in the scientific world) where CO2 can go up and down by 100 ppm and not have a large impact on the climate.

  • At February 20, 2007 4:35 PM, Anonymous Anonymous said…

    The CO2 lags behind temperature by centuries in the glacial-interglacial cycles, so clearly CO2 does not cause temperatures to rise, temperatures cause CO2 to rise.


    Well either the CO2 lags behind temperature or it doesn't, I see no evidence provided by you that shows that CO2 does not lag behind temperature.

  • At March 02, 2007 3:57 AM, Anonymous Anonymous said…

    CO2 lagging is a red herring by the contrarians.
    CO2 during the ice ages is a natural response of temperature (soda bottle outgassing), that fact doesn't predict anything if you artificially add extra CO2 into the atmosphere.

  • At March 07, 2007 1:22 AM, Anonymous Anonymous said…

    Your answer (& real climate's answer) is not an answer and it certainly doesn't address the fact that temperatures also start going down 800 years before co2 levels go down.

    Not only is this hard to explain given the "evils" of co2, but it seems to further re-enforce the most obvious conclusion -- that co2 follows temps.

    If I started going to the gym and 6 months later I was fit... and then I kept going to the gym for 10 years and stayed fit, then what caused what? Then I stop going to the gym and 6 months later I'm fat & slow again. What is the most logical explaination for this?

    If somebody tried to say that being fit caused me to go to the gym and pointed to the 10-year correlation, I would be more than a little skeptical.

  • At March 08, 2007 7:05 PM, Blogger coby said…

    Hi John,

    Yes, the obvious conclusion about the glacial/interglacial cycles is that CO2 follows temperature. Now why do you chose to turn this into an immutable law, "CO2 can only follow temperature." The fact is that temperature effects CO2 by changing the soluability of carbonic acid in the oceans and CO2 effects temperature due to its radiative properties. There is no smoking gun of socialist propaganda here!

  • At March 13, 2007 6:46 PM, Blogger IanRae said…

    The issue here with C02 and T isn't which causes which. The issue most skeptics have is that the historical T and CO2 records are used (especially in Gore's film) as evidence, when in fact the historical data is counter-evidence.

    I am quite willing willing to believe that physics says rising CO2 will cause more absorption. But where is the historical proof of this? As people here point out, T falls in these 5000 year surges even with high C02.

  • At March 13, 2007 7:00 PM, Blogger coby said…

    Hi IanRae,

    This lengthy record is indeed excellent evidence of a strong connection between CO2 and temperature. Regardless of the intricate details it is very strongly suggestive that GHGs are critical elements in determinng the global climate. The possibility that T moved first (this is likely, but it is not an easy thing to be sure of) is not corroborating evidence for what is happening today but it is not contradictory either. You are correct that it is not an example of a CO2 triggered warming but there are such in geological history, the PETM event for example as well as the deccan traps and possiblehythe Great Dying.

  • At March 14, 2007 10:26 AM, Blogger Luboš Motl said…

    Your comment that they rise "mostly together" is simply stupid.

    If you were an inquisitor, it would be enough for you to hide 10% of the evidence, and people would be unable to determine whether the temperature is the driver and the gases consequence, or the other way around.

    But the scientists who don't make censorship of the available data can look at these critical regions, determine the gap, and be sure that the temperature leads and the gases lag, which is why the influence of temperatures on CO2 concentration is stronger than the opposite influence.


  • At March 14, 2007 12:01 PM, Blogger coby said…

    whether the temperature is the driver and the gases consequence, or the other way around.

    That is what is called a false dichotomy, the realm of possibilities is not restricted to this mutually exclusive choice.

    CO2 rise is both caused by and a cause of temperature rise. Temperature rise is both caused by and a cause of CO2 rise.

    So simple, even a Lubos Motl can understand.

  • At March 14, 2007 1:40 PM, Anonymous Anonymous said…

    Post hoc ergo propter hoc...

    Suppose you were an insurance claims investigator and that you have arrived at a huge meat warehouse filled with tons of rotting sides of beef.

    A claim has been filed that there was an interruption to the the electric service that powered the locker's freezer. A temperature chart has memorialized the event and you as the owner are secure that your claim will be covered.

    Not so fast, says the claims investigator!

    He believes that the cause of the rise in temperature was merely the rotting of tons of bad sides of beef you stored within it. As they rotted they released chemical energy in the form of heat and C02 thus overwheming the locker's feezer; you point to the temperature chart as evidence - claim denied.

    Further the locker was sealed and current samples of C02 within the airtight freezer confirm the claims investigator's rotting beef theory as the most plausible cause of the temperature rise. It's not tempurature rise = rotting beef = C02, but instead it's rotting beef = more C02 = higher tempurature. ie global warming theory

    Appeal for the claim denied!

  • At March 17, 2007 4:16 PM, Anonymous Anonymous said…

    Looks like the "deniers" have won this argument to me. Does an example of CO2 leading temperature exist? I haven't seen anyone argue that point. At best, it seems possible to argue that it could, but based on the historical record it seems equally possible that the earth could cool against rising CO2 levels.

  • At March 17, 2007 4:27 PM, Anonymous Anonymous said…

    Also, those that argue the certainty of anthropogenic global warming are clearly capable of being "skeptics," if not outright "deniers," of the evidence that suggests that CO2 levels trail temperature changes. I say, good on them for casting doubt on the strength of the evidence for this correlation. But why are they so unwilling to grant the benefit of the doubt to those on the other side of the debate?

    There was once a "consensus" that the earth was flat, but consensus did not make it so.

  • At March 21, 2007 2:51 PM, Blogger coby said…

    Does an example of CO2 leading temperature exist?.

    Google the PETM or Paleocene-Eocene Therml Maximum. There is also substatntial evidence pointing to CO2 driven warming (wth dire consequenes) as the cause of The Great Dying.

  • At March 22, 2007 9:15 AM, Anonymous Anonymous said…

    The before or after nitpicking makes no sense to me as I look at the ice core graphs. The dance these two lines are doing together tells me they are related, directly, to one another.

    If you must argue over b4 and after what about the fact that the top concentration has been 280ppm for eons and it is now roughly 380ppm. That's a 36% increase in roughly 150 years. If temperature rise precedes GHG increase, where is the 36% increase in temperature more than 150 years ago? If the lag is longer tell us where the temperature increase is located on the time line.

    What's seems important to me is that the atmospheric ecosystem is so delicate it is controlled, temperature wise, by a substance that makes up only one four hundreth of one percent of the total.

    If you look at the graphs of the ice cores you can see a levelling off of the increase starting 11,000BP and then resuming the increase 13,000BP. Does that correlate to the ice age generally believed to have occurred at that time?

  • At March 23, 2007 2:12 AM, Blogger Zebadey said…

    Just one thought, before I post I will state my position I am an environmentalist who takes the contravertial position that the levels of C02 are an effect not a cause of Global temperature increases. Also raising the point that global temperature modeling programs that do not take into account the effect of our big old energy source in the sky are fundementaly floored. We should be cutting back on use of fossil fuels due to the resource dwindling not because people are running round saying the sky is falling down, because as soon as it doesn't people will go straight back to their bad old ways and run the wells dry.

  • At March 24, 2007 5:27 PM, Anonymous Anonymous said…

    Here, here!
    Plenty of good reasons to cut back on fossil fuels. But CO2 levels warming the earth are not it and we will eventually accept that fact. CO2 is an extremely minor greenhouse gas. Man-created CO2 is miniscule. And then to top it off, greenhouse gasses don't cause global warming in the first place. I really don't know what else these peoople need to face the truth.
    But back to the main point we should be finding alternatives for other much more important reasons which seem to me to have been forgotten amidst the false hype of man-made global warming. It's very sad.

  • At March 26, 2007 8:18 AM, Anonymous Anonymous said…

    Would someone please explain to me the physical process in which CO2, methane, or other gases aside from water vapor contribute to global warming. Do these gases reflect/refract IR or UV radiation? Are they ionized? Are their states changed? If these gases are indeed the problem and not a symptom, then how do they reflect/refract IR radiation back to the earth?


  • At March 26, 2007 9:34 PM, Blogger coby said…

    Hi Jack,

    CO2 and methane and all the other GHG's work the same way as H2O, so I am not sure why you specified "aside from water vapour". Basically what happens is that these gases are transparent to shortwave light, which is the majority of incoming solar radiation, a thus allow it to pass through to the earth's surface which is thereby warmed. As the earth warms up it begins to emit infra red radiation. GHG's are those that block this outgoing longwave radiation. At certain wavelengths a radiatively active gas will absorb photons and then reemit them in a random directions. This way roughly half of the absorbed radiation is sent back to the earth's surface causing more warming. Eventually the surface reaches a point where it emits enough IR that the half making it out into space balance the total amount of incoming SW and LW radiation.

  • At March 27, 2007 2:05 PM, Anonymous Anonymous said…

    Regarding the Paleocene-Eocene Thermal Maximum, there is plenty more evidence that suggests this was caused by a giant methane release, not CO2. And methane is about 20X more effective at being a greenhouse gas than CO2....

  • At March 27, 2007 7:00 PM, Blogger coby said…

    Yes, molecule by molecule CH4 is 20x stronger than CO2 as a greenhouse gas. It is also in much smaller concentrations, measured in ppb not ppm. But it also has a very much shorter lifetime, breaking down into CO2 in a decade or two.

    Regardless, the point is warming by ghg's. Why are you ok with the idea that CH4 (in ppb) can drive a warming but not CO2 (in ppm)? The ice core records show CH4 and CO2 tracking very closely.

    Are you saying that CH4 can drive warmings despite the fact that it follows temperature in the ice cores, but CO2 can not because it follows temperatures in the ice cores?

    Eventually you will have to stop squirming and accept clear evidence.

  • At March 27, 2007 10:10 PM, Anonymous Anonymous said…

    Is it possible that since the earth is constantly spinning that the earth has become a sort of centerfuge and that the CO2 and methane are flung outward towards the ionisphere and have to saturate the lower atmosphere before showing up in the ice cores? This would explain rising temps closely followed by CO2 levels going up.


  • At March 28, 2007 10:13 AM, Anonymous Anonymous said…


    You pointed to the PETM as being an example of CO2 induced warming.

    Your post:

    "Does an example of CO2 leading temperature exist?.

    Google the PETM or Paleocene-Eocene Therml Maximum. There is also substatntial evidence pointing to CO2 driven warming (wth dire consequenes) as the cause of The Great Dying. "

    When in fact ample evidence supports that this event was caused by a massive METHANE release from the oceans. Evidence also suggests the earths temperature changed extremely rapidly following this release (on the order of a decade) well within the timeframe Methane breaks down to CO2.

    Yes, it is true that currently Methane makes up very little of the earth's atmosphere. Right now in 2007. Was that the case immediately after that huge release?

    Saying the PETM was cause by CO2 is at BEST a misleading statement, and quite possibly 100% innacurate.

  • At March 28, 2007 11:17 AM, Anonymous Anonymous said…

    And methane is NOT currently measured in ppB. It is currently about 1.8 ppM.

    "The methane concentration in the air is presently some 1.8 parts per million (ppm) and is growing at a rate of 1% per year. Although this concentration is far less than that of CO2, methane is 30 times as potent a greenhouse gas and so may now be responsible for 15–20% of the predicted global warming."


    So, put ALOT of a gas in the atmosphere that is 20-30X more effective than CO2 at trapping heat and....there you go. PETM.

  • At March 30, 2007 8:20 PM, Anonymous Anonymous said…

    I Am Not Climate Scientist, nor do I play one on TV. But I am a man with a very high IQ and an flair for analytical reasoning, and I can smell a logical fallacy from a distance of thousands of miles. Your attempt to dismiss the "CO2 Lags" argument stinks to high heaven.

    In any system where a leading cause is followed by a trailing effect, both will move together after an initial lag. The fact that they're moving together does not, in the slightest way, give you leave to pretend the initial cause is no longer the driving force -- but that's precisely what every article linked to this explanation has done. It's just, plain, wishful thinking.

    The most striking characteristic is the frank admission by nearly everybody that we do not know what the initial cause really is. But you folks want so very badly to prove that CO2 is the culprit that you don't even direct your inquisitory power at what the cause might be; you simply pretend it doesn't matter after CO2 appears on the scene, and talk about a feedback loop -- in a system where you don't even know what the driving force is!

    It's pretty obvious that you're letting a desired outcome influence your scientific judgment. What you should be saying is "It looks as though the CO2 is an effect (because that's true, it really does), but we really won't know until we understand the initial cause." Once you actually know what the primary cause is and how it interacts with CO2, THEN, and only then, will you have a basis for saying whether CO2 plays a significant role in the warming or not.

  • At March 30, 2007 11:10 PM, Anonymous Anonymous said…

    ^^^That, is a great post.^^^^

  • At April 01, 2007 4:31 PM, Blogger coby said…

    [addressing multiple comments at once here]

    Hi rich,

    One minor nitpick: you meant 4 one hundreths, not 1 four hundreth!

    Re ice age 11000bp, you may mean the Younger Dryas event? That was a N hemishere phenomenon with interesting features unrelated to ghg changes.

    Hi Zebady,

    before I post I will state my position [...] that the levels of C02 are an effect not a cause of Global temperature increases

    Science is a matter of empirical reality, not personal opinion. Your position has no basis in empirical reality.

    There is no global temperature modeling program used by serious researchers that does not take into account the effect the sun, in fact it is a pretty bizarre idea.

    Anonymous and the PETM:

    You have no source for your claim that the PETM developed over one decade. The proxies available can not resolve to less than many thousands of years.

    I take it you have conceded the broader point that the ice core records do not rule out the possibility of ghg driven climate change?


    Try feeding that high IQ of yours a bit more information. All your reasoning requires the assumption that we have a system with only two variable factors with uni-directional inter-dependence and all we know about it is that which is contained in the ice core records. The picture is much more complex and the available data varied and rich coming from a wide variety of sources including modern day lab experiments and very high tech observations of the system today.

    Go read the IPCC TAR (link in the side bar -- "Scientific Basis")

    Thanks all for the comments!

  • At April 13, 2007 7:23 PM, Anonymous Anonymous said…

    It is truly telling when no one can give an adequate explanation of the CO2 lag. But even more telling is the fact that many man-made global warming theorists "conveniently" use various tactics to hide the obivous. In Gore's movie, he gives ample space between the C02 and Temperature trend line when graphing so as to hide the lagging effect. Others will reverse the timeline or use large fat lines to minimize the seperation. However, most will simply not provide an icecore graph when explaining the theory.

  • At April 15, 2007 3:07 AM, Blogger coby said…

    Hi charles d,

    You should not be suspicious that it is extremely difficult to reconstruct climate changes that occured long before anyone was around to measure and observe the multitude of parameters involved in a complex, dynamic system.

    That said, what do you find inadequate about the current hypothesis that CO2 rose in response to warming because its soluability in water (oceans) is lower at higher temperatures? The timeframes of overturning oceans and the lag are intriguingly similar.

  • At April 29, 2007 12:20 PM, Anonymous Anonymous said…

    CO2 is an indicator of overall biological activity and is the EFFECT of global temperature change NOT THE CAUSE. The biological respiratory cycle depends on and drives CO2. When the physical solar and orbital cycles of the earth and sun cause the earth's temperature to rise(THIS IS THE CAUSE) the entire biological activity level of the earth begins to increase. But it lags the temperature due to the massive inertial volume and complexity of the biosphere (all air, land and water). Forest biomass takes hundreds of years to peak. How long it takes for a tree to mature? Fossil fuels represent massive amounts of biological mass that was trapped suddenly millions of years ago by cataclysmic events. Releasing it will actually enhance biological respiration and stabilize temperature. The CO2 will increase the rate of growth of plants which will actually keep temperature down. CO2 as a greenhouse gas is a very minor player and exists in the atmosphere in extremely very small quantities compared to water vapor for example which is the main greenhouse gas. For a very stark proof of this compare the pre sunrise temperature in the desert that had a 90F peak temperature in the afternoon and a 10F dew point to let's say Miami with a 73F dewpoint. You would be lucky if Miami will drop to Oh maybe 80F while the desert will drop to perhaps 40F or even less. That's the greenhouse effect. I find it amazing that when Al Gore graphed the ice core data for temperature then plotted the CO2 on a separate chart below it and never bothered to line up the time scale to show the lags of hundreds of years. Come on Al you little liar!

  • At May 01, 2007 4:29 AM, Anonymous Anonymous said…


    I agree that the lag is likley caused by the oceans storing and releasing CO2 but where is the causal effect? How can you claim that something else causes the temperature to rise and then something else causes it to go down but then blame CO2 for everything in between? If that were the case then why haven't temperatures gone through the roof with the recent sharp increase in CO2 levels? Do you have any other examples of this type of feedback system in nature? It just doesn't add up to me. It seems that man-made global warming theorists have put all their eggs in one basket and will defend the idea to the death, despite gaping holes in their theory and all evidence to the contrary. I think it is you who are the "flat earthers".

    What do you say about the fact that Mars, as well as other planets, have been going through a warming period very similar to ours? How can you explain this?

  • At May 03, 2007 11:05 PM, Blogger coby said…

    Hi Charles D,

    I don't attribute everything in between to CO2. In total, CO2 and CH4 contributed about half of the overall forcing from glacial to interglacial. Things very well may "go through the roof" with today`s CO2 spike, but the system is large an has a lot of thermal (and other kinds of) inertia. Carbon cycle feedbacks could take many centuries to really come into play for example. It does not seem all that complicated to me, much less far-fetched grasing at straws.

    As for Mars, there is an article on that here, but a more comprehensive look at the rest of the solar system can be found via this recent article:

    I dont thnk there is much justification for aying any warming on Mars is very similar to ours. How on earth do you know that?

  • At May 21, 2007 4:40 PM, Anonymous Anonymous said…

    Wow, the logic on this website is so flawed and week that I just don’t believe your clearly biased arguments.

    I was hoping for an argument one way or the other that stood up – but the poverty of your argument makes me inclined to think your premise is also wrong. I don’t know that because I don’t have the evidence one way or the other, but your website at least makes me know what you is saying is ill founded nonsense.

    Your premise might be right, I don’t know, but your logic is just biased twoddle, that I am inclined to think someone who spouts such twoddle has nothing of value to say. I guess I will have to look elsewhere for some real information one way or the other on this subject.

  • At May 22, 2007 1:29 PM, Blogger coby said…

    someone who spouts such twoddle has nothing of value to say

    How..um..... ironic.

  • At May 29, 2007 4:52 PM, Anonymous Anonymous said…

    Hmmmm...I think maybe people need to do a bit more reading and less of dismissing arguments without properly understanding them!!

    To anonymous who said this:

    What happens if we become zealously proactive? What if "engineers" start trying to actively "cool" the globe? And don't say awe that can't happen... too many historical examples of that being proven wrong...

    This could be a problem; but the earlier we act the less extreme the measures need be. To be honest I think this is less of a problem than people simply ignoring/denying Anthromorphic climate change because they don't like and they don't understand the arguments about it!

  • At May 30, 2007 9:18 AM, Blogger ALLAN AMES said…

    Anonymous had a point about plants.
    I have crosscorrelated the Vostok data, both non- and paramtetrically. Declining O18 leads rising CO2 by 3000 (+/-) years, significance off the chart. Whatever is going on has nothing obvious to do with CO2 driven warming. To have the charts and program, convince me.


  • At June 04, 2007 5:38 AM, Anonymous Anonymous said…

    Excellent opinions.
    My position, THC variation didit. Temp/CH4/CO2 rising/falling are the effects. What drives the THC? Maybe solar cycles.
    It is nonsense to use ice cores as evidence of CO2 levels as Antartica has its own climate and other data implies serious doubt to the veracity of measurements. Without it and Mann made GW with the hokey stick, and with evidence of far higher CO2 levels in recent centuries, expect the greenies to lose their case against the Canadian govt. Expect Canada to sue the UN for deception.
    AGW is a political scam joy ridden by bent profiteers like carbon traders and movie makers. Griffin needs to demote or sack Hansen now or be dragged down by the scandal.
    Nature finds its own balances such as increased phyto plankton, increased sea surface, the carbon absorbing treeline limit moving to higher latitudes bringing more CO2 absorbing trees into the game, increased rainfall etc. Oh, and according to the ice core data, at a certain level CO2 reaches saturation and becomes a negative or neutral feedback evidenced by falling temperature /rising CO2. CO2 drives cooling. CO2 is not the problem. Temperature might possibly be a problem, except for handwaving, toy models and lies there is no evidence of anything except weather..
    We have temp driving CO2 perhaps, definitely not the reverse. But AGWers claim the reverse. We have El Nino events definitely leading temp but AGWers are now intimating the reverse, well it worked once...
    Off to the beach to enjoy the fine weather and before the 'AGW causes cooling' deception kicks in.
    Kyoto - $1bn buys 0.00001 deg C in 50 years if the weather does as Hansen tells it to. Well it can't fail to, his chart says it's going to get very hot- or a little warmer - or cooler due to AGW. Got to take your hat off to the mann selling that boatload of it.
    Creationists back the AGW hypothesis. Says it all.
    Check out http://www.climateaudit.org/ for the latest on 50% or more Hansen data stations may be useless, and motls.blogspot.com for real scientists' blogs.
    There's lies, damn lies and AGW.
    Rant mode - off. :)
    Lets hope we all find the truth soon. soon.

  • At June 04, 2007 12:37 PM, Blogger Mark said…

    "...we may well see additional natural CO2 come out of the woodwork as whatever process that took place repeatedly over the last 650K yrs begins to play out again. The likely candidates are outgassing from warming ocean waters..."

    Actually, more CO2 is being desolved into the ocean due the the sharply raised levels. It was basically at equalibrium, and now more has to go into to ocean to restore it. This is causing the ocean to become more acidic.

  • At June 04, 2007 12:44 PM, Blogger Mark said…

    "You can also go here ( http://www.realclimate.org/index.php?p=13 ) for a discussion by climate scientists of exactly this question but with greater technical detail and full references to the scientific literature."

    I'm suprized you though that post was adequate. On the face of it, for the layman, temperature rises causing CO2 to come out of the ocean, with no feedback effect, seems like a perfectly reasonable explanation. They don't explain at all why the data shows a feedback effect, or what the mechanism is that stops the positive feedback from being a runaway process (a frequent question by skeptics).

    I though realclimate did a terrible job of explaining this and addressing skeptics questions.

  • At June 18, 2007 8:44 AM, Anonymous Anonymous said…

    Ice ages have come and gone - without any human produced CO2. Have fun on your bike ride, but AGW is a bunch of political BS.

  • At June 23, 2007 8:59 PM, Anonymous Anonymous said…

    April 29th 2007 Comment by anonymous. Your comment is intriguing about the wild runs of temperatures where there is no water vapor. But I have read that the warming over deserts, paerticularly high deserts, is larger than it is elsehwere. Since there is very littloe water vapor, the argument is that CO2 (and other gases like CH4 and O3, etc) are causing the warming. Please comment. cjtoomay@cs.com

  • At June 23, 2007 9:00 PM, Anonymous Anonymous said…

    April 29th 2007 Comment by anonymous. Your comment is intriguing about the wild runs of temperatures where there is no water vapor. But I have read that the warming over deserts, paerticularly high deserts, is larger than it is elsehwere. Since there is very littloe water vapor, the argument is that CO2 (and other gases like CH4 and O3, etc) are causing the warming. Please comment. cjtoomay@cs.com

  • At July 16, 2007 12:18 AM, Anonymous Anonymous said…

    In "Climate change and trace gases" (May 2007), Dr. Hansen admits that temperature leads CO2 increases. In one case, CO2 increased 5,000 years after the temperature increased. To "fix" this problem, he proposes faking the data (changing the timeline) to support his theory.

    In the same article, Hansen strongly disagrees with the IPCC because they are not radical enough.

    My impression reading this is that Dr. Hansen realizes that since this data proves his theory wrong and he is actually willing to "modify the data" to try and keep AGW alive.

  • At July 16, 2007 8:52 AM, Blogger coby said…

    Hi Robert,

    As your characterization of what Hansen says in this article is completely wrong, yur resulting impression of what he does or wants to do is ridiculous.

    As this post clearlystates, the fact that the initiation of CO2 changes likely followed the initiation of temperature changes is not a "problem" that needs "fixing". It fits well with both theory and modeling experiments.

    Thanks for the comment.

  • At July 16, 2007 10:48 AM, Anonymous Anonymous said…

    Actually, he said that if CO2 actually changed more than 200 years after the temperature increase, then the oceans would have gotten way too hot. To quote

    "Proof is obtained by considering the contrary: ice sheet forcing approximately 3W/m^2 and a 5 kyr timing gap between forcing and response, as appears to be the case at Termination IV (figure 2c), is 15,000 W yr/m^2, enough to warm the upper kilometre of the ocean by approximately 160 C" (pdf page 7)

    This is his justification for modifying the data - not my "characterization" of what he said.

    The other way to interpret his statement is that "increasing CO2 does not increase temperature". So, either he has to modify the data to fit the theory, or he has to change the theory. If this was said by anyone except Hansen, we could just blow this off .....

  • At July 16, 2007 11:47 AM, Blogger coby said…

    Hi Robert,

    Try to remember that these data are not simple to derive, nor are they uniform, error free or 100% certain. What Dr Hansen is pointing out in this particular passage is that a very anomalous portion of the record does not make sense. That is, everywhere else in the record as best as we can tell, GHG changes begin to occur approxiamately 600-800 years after the temperature begins to change. At termination IV (330Kyr BP) the data analysis indicates that there was a 5000Kyr lag, almost 10 times as long as the others. He has presented what you quote above to show that there must be an error in the analysis at this point. You have further misconstrued the point by saying "more than 200 years" when in fact the passage is about a 5000 year anomaly and a lage of 600-800 years is presented and accepted everywhere else.

    So what he has said, is "look at this large inconsistencey here. If it were real, then the oceans should have boiled from ice sheet albedo feedbacks alone. As they clearly did not, there must therefore be an error in this data".

    You have taken this entirely reasonable and standard scientific way of thinking and claimed that Dr Hansen "proposes faking the data ... to support his theory". I believe I was quite kind to you to say you were merely wrong in your characterization.

    Sorry, no evil conspiracy here, cooking the science to support UN world domination, just the scientific method at work.

  • At July 17, 2007 10:51 PM, Blogger Thorpe said…

    Hi Coby,

    Many thanks for this excellent site. It is hard to get thoughtful discussion on these issues.

    I am particularly interested in your exchanges with Whit and Bob (although I suspect I haven't had time to read all the comments). The issue of "turning the corners" from warming to cooling and back again is the one that most bothers me. If CO2 causes most of the warming after a small intial forcing from orbital change then I would expect that more warming would cause more CO2 which would feed back to even more warming and so on.

    To turn the corner the suggestion would seem to be that a small forced cooling from orbital change would then lead to more widespread cooling which in turn absorbs CO2? At this stage the warming effects of atmospheric CO2 would presumably no longer operate because the remaining CO2 does not seem to interfere with the cooling.

    There is a hypothesis for the mechanism of CO2 warming. Do you know if there is a hypothesis for how the cooling happens in the presence of a lot of CO2?

    I think that this argument is quite important. I assume that there is a reasonable hypothesis for how CO2 accomodates cooling which is supported by observational evidence at least. I am interested to know what it is.

    It seems to me that any thesis that explains CO2 in warming but cannot accomodate CO2 in cooling can only be described as speculative (I'm not saying it must be wrong, but it would certainly be incomplete).

    Advocating policies involving widespread social and ecomonic change on the basis of an incomplete hypothesis does not seem wise to me.

    As a postscript, I have really enjoyed everyone's comments on this blog, but I have difficulty with people who post anonymously; especially when there are two of them talking to each other! If you make public comments you place your reputation at risk. If the comments are respectful, moderate and thoughtful then the risk is negligible; even if the comments are wrong. The alternative is to always be right. But if you're always right, why would you want to be anonymous?

  • At July 24, 2007 7:20 PM, Blogger coby said…

    Hi Thorpe, sorry for such a tardy reply.

    AFAIUI, the cooling mechanism is just the reverse of the warming. As soar forcing in the NH decreases, the ice begins to expand which creates a positive feedback due to ice's high albedo. This causes the oceans to begin cooling and thus drawing CO2 out of the atmosphere. This removes a portion of CO2's warming influence which is another feedback.

    GHG's in the atmosphere keep the earth about 33oC warmer than it would be otherwise, so the 5o up and down of the ice ages is not the whole ball of wax by any means.

    Thanks for the comment!

  • At August 16, 2007 11:59 AM, Blogger Unknown said…

    As a latecomer to the depths of these excellent discussions there are perhaps assumptions you've all got behind you, so please forgive what may be an obvious question.

    It's clear that there isn't much dispute about which comes first in the proxy records but what part does differential concentrations at altitude play in this debate?

    In other words, is there a lag between the time CO2 appears at altitudes where it has an effect and the time CO2 appears in the proxy records at the surface where it can be measured? If so, does anybody know how long that lag might be?

  • At August 16, 2007 8:07 PM, Blogger coby said…

    Hi Jeff,

    CO2 is considered a well mixed gas in the troposphere. That is to say that concentration varies very little with altitude, longitude and latitude on timescales less than a decade. There is about a 4 year lag time between levels in the NH where the bulk of CO2 is produced and levels in the SH. This is to fast to matter for climate change which happens on the scale of decades. Any shorter time scales and chaotic natural flucuations outweigh and climatic trends.

    In the proxy records (ie the ice cores) the rise in CO2 is ~50x slower than what we see today, so any lag between source and atmosphere will have even less effect.

    However, the nature of the GHE does change as one gains altitude which is why the absorbtion bands in CO2's radiative wavelengths are not saturated in the sense that additional CO2 has no additional GHE as a naive understanding might indicate. (See RealClimate, here and here.

    HTH, thanks for the comment!

  • At January 12, 2008 7:52 AM, Blogger wow said…

    Hi Coby, You wrote (6 April 2008):
    "There needs to be a mechanism whereby atmospheric CO2 is increased. AFAIU during the glacial cycles the only mechanisms proposed for this are reactions to rising temperatures."
    Sigman & Boyle (Nature, 407, pp 859-869, 2000) discuss some other mechanisms. I don't buy their thesis, just thought you should know.

  • At February 03, 2008 12:28 PM, Anonymous Anonymous said…

    A very interesting post with good points on both sides.
    Much of the ice core data is the product of modeling, necessary because co2 wanders about, even reacting with the atmosphere from 50+ meters down.
    Co2 apparantly has the ability to stop forcing at arbitrary densities.
    Co2 was temperature led by 1 month in recent decades.
    Temperature leveled post 1998, that indicates water vapor stopped increasing or reached saturation or we ran out of IR.
    Methane volume stabilized, whether that was due to anthropogenic or natural causes is guesswork. It could have reached a balance in oxidization equaling increase, a saturation point.
    Solar insolation decreased for whatever reasons, aerosols, sunspots etc.
    El Nino declined into La Nina phase as the ocean cooled over the last few years.
    Tilt and orbital position are best replicated in MIS11, apparently, water levels were higher by ~20mtrs. Maybe the planet was smaller.
    So anyone with 2 braincells can cobble up a prime mover and substantiate it with cherries.
    Hansen's prime mover has proved the inaccuracy of his modeling. Adjust lambda to Hansen values and co2 forcing would have us degrees warmer. His charts need adjusting for naturally demonstrated values, ie insignificant to zero forcing for the nominated co2. Retaining his fanciful lambda values puts all the temperature spaghetti-strand guesstimates way off. Accepting what the rest of the world understands lambda to be leaves a vacancy for a forcing agent extraordinaire. Or several very ordinary actors in harmony, not forgetting conduction and convection. And the weather, never trust it, it's 50%+ unpredictable in the short term, 100% unpredictable with known ability in the long term. As Hansen continues to demonstrate.
    The pessimists appear to be on the retreat in the co2 did it front, it is rarely mentioned, GHGs or anthropogenic whatever usually cop for the blame. A new twist is anthropogenic water vapor. Get it while its still hot (air).
    Global warming stopped. Co2 is obviously not forcing. Why does the carbon credit con continue? Why is kyoto conu2 continuing?
    Why am I paying carbon tax? In case co2 makes seas more acidic?
    Wolf? What wolf?

  • At March 05, 2008 4:29 PM, Blogger barry said…

    It is not logically inconsistent to posit that CO2 increase in the atmosphere comes after temperature rises, and to then posit that CO2 can cause further warming. The two posits are NOT mutually exclusive per se. Both can be true. There are examples of this type of feedback throughout the world in the atmosphere, in the mechanical world, and in the human body.

    In lab experiments stretching back decades, it has been amply demonstrated that increasing CO2 in a sealed volume impedes infrared radiation passing through that volume. This is the empirical basis for the the theory of anthropological global warming.

    From this empirical evidence, it is theorized that infrared radiation welling up from the surface will be impeded by an increase in CO2. If more radiant energy is trapped in the atmosphere, the atmosphere will heat up.

    In order to debunk AGW theory, it is necessary to demonstrate that what happens in the laboratory will not happen in the atmosphere. This has not been done.

    Ice core evidence strongly suggests that previous CO2 increases in the atmosphere have lagged temperature increases (by about 800 years).

    Interglacial temperature increases typically last 5000 years. Therefore, the first 800 years of warming is not caused by CO2 increase. This is roughly 1/6 of the total warming period. Warming still occurs for the next 4200 years, 5/6 of the warming period.

    Based on the empirical evidence of the laboratory experiments, it is quite possible that the increasing CO2 in the atmosphere during interglacial periods could have amplified the warming already occurring.

    The most likely cause of climate shifts from glacial (ice age) to interglacial periods is orbital variation, is corroborated by a very strong correlation between large global temperature changes/atmospheric CO2 fluctuation and phases of Milankovitch cycles. The fit is excellent.

    We are currently going through a Milankovitch period which takes us further away from the sun. We emerged from the last ice age about 10 000 years ago, and the global temperature trend has been downward for the last 8000 years. The next ice age brought on by orbital variation is projected to occur in about 50 000 years. We should be in a period of cooling.

    CO2, then, would be falling at this time if natural variation was dominant. But it is absolutely uncontroversial that CO2 in the atmosphere is rising (see post on CO2 accumulation).

    We are therefore experiencing a probably unprecedented rise in CO2 before temperature rise, and this rise is clearly coming from human industry. That is also uncontroversial.

    Therefore, while past periods of temp/CO2 rise may tell us something about feedback (orbital variation cannot account for the total temperature rise during interlgacials), they do not tell us what happens if the CO2 increase precedes temperature increases.

    For that we need to go back to the lab experiment, the empirical basis of global 'greenhouse' theory, and pit that empirical evidence against the hugely complex real-world environment. To date, while various effects and feedbacks constrain the certainty placed on recent and projected climate change (EG, albedo change, the response of water vapour, various future emissions scenarios etc), it is virtually certain that CO2 increases from human industry have reversed and will continue to reverse the downward trend in global temperatures that should be expected in the current phase of the Milankovitch cycle.

    If there is a natural mechanism that explains the current upward trend of global temperature, it has not been discovered (solar cycle is also at a low ebb for the last 50 years, for example). The CO2 increase from industry fits the bill. Nothing else does. The mainstream view of climate change is robust - that is, it is validated by a statistically significant number of scientific tests.

    On this topic critics must explain;

    1) Why CO2 cannot have acted as a feedback in past interglacials.

    2) Why increasing CO2 in the atmosphere would not lead to warming.

    3) What the natural mechanism is that is causing the current warming.

    The hypothesis for past CO2 lag was put forward 18 years ago. In the following years, analysis of ice cores appear to have corroborated this posit. The science is still uncertain, but there is much less doubt that CO2 lags.

    The IPCC first made mention of the lag of CO2 in its 2001 report, and again in the 2007 report as the science became more solid on this. CO2 lag in no way scuttles AGW thery, but adds to the understanding of how the climate has varied in the past, and what might be anticipated of a rise in CO2 in the current era.

    I realize I have more or less restated the principles in the top post, and repeated some of the argument that has followed. I've done so because there appears to have been a lot of dissonance and misunderstanding in the ensuing debate, and I wanted to try and straighten it out.


  • At March 18, 2008 5:01 PM, Anonymous Anonymous said…

    I'm a normal person, not a scientist. In Al Gore's movie he claimed that CO2 is both causes increase in temperature and is caused by increases in temperature. I want to hear the opposing viewpoint but everytime I hear it they leave out that part.

    So it seems that if naturally CO2 lags but is it possibly that when humans enter the mix that our CO2 production is leading the warming?

    Every reference to his movie points out that CO2 lagged 400-800 years ago but they never address what's happening now. It ironically seems that both sides are conveniently avoiding a head on collision to find the truth.

    One thing is for sure, the debate is not over.

  • At March 21, 2008 6:24 AM, Blogger Clothcap said…

    Barry, sir.
    The onus is on the proponents to
    1) Demonstrate how CO2 acted as a feedback in past interglacials.
    2) Why increasing CO2 in the atmosphere would lead to more than insignificant warming.
    3) What the natural mechanism is that drives warming.
    None of which has been done by much more than hand waving whilst you are asking skeptics to do the science.
    Co2 crosses temp going down as it goes up. Co2 crosses temp going up as it goes down. Co2 leads temp. Co2 trails temp. Co2 and temp also wander around completely disassociated. Check the ice core data.
    There is a finite amount of IR. Co2 and h2o compete for it. There is sufficient co2 in the air to capture the available radiation 3 times over. Doesn't that in itself suggest something?

  • At May 24, 2008 9:49 AM, Anonymous Anonymous said…

    Hi Clothcap, haven't visited the site for a while. Hope you return to read my reply to you.

    Barry, sir.
    The onus is on the proponents to

    1) Demonstrate how CO2 acted as a feedback in past interglacials.

    This has been attempted, and is part and parcel of the theory of climate change.

    The simplest method is to calculate how much heating effect solar influence has when the Earth's orbit moves the planet closer to the sun during interglacial, and compare that with proxy records of how much the temperature changed during that time - during the interglacial. If the temperature change is greater than can be accounted for by Earth's nearing the sun during the Milankovitch cycle, then something else must be contributing to the warming.

    Although it is difficult to place temperature and CO2 records together from proxies so far back in time, the best estimate is that CO2 contributed 1/3 of the total warming - more if you include other greenhouse gases. Orbital wobble (proximity to sun) cannot account for the total warming (or glacial period cooling).


    2) Why increasing CO2 in the atmosphere would lead to more than insignificant warming.

    This is a little vague. What is 'insignificant'?

    Radiation budgets are a central component of global warming theory, and have been addressed for over a century. However, it was not until the 1950s that scientists got a good grasp on the complexity of the atmosphere, discovering, thanks to measurements taken for other purposes by the US air force, that the atmosphere is many-layered. Since then, satellite reading of temperatures and the occlusion of numerous infrared bands, ground based, aircraft and balloon measurements of same, and an ever-increasing data base of the optical properties of CO2 (and other gases, like water vapour), have helped refine radiation calculations towards determining the atmospheric heat budget. There are, literally, thousands of studies on it, and the results are very robust. I've seen numerous skeptical articles (not peer-reviewed, though - there doesn't seem to be any) that attempt to demonstrate a less significant warming from CO2 increases in the atmosphere, but they are all flawed by fundamental errors, and very few, if any, are done by people with expertise in the subject.

    3) What the natural mechanism is that drives warming.

    This is strange. There are natural processes that drive global climate warming, like Milankovitch cycles, and these are accounted for in (for example) the IPCC reports, as well as numerous studies. There is no one natural mechanism.

    Climate scientists have not (successfully) found a natural mechanism driving the current global warming (of the past 150 years). AGW skeptics regularly attempt to do so, but none have succeeded as yet. The last attempt I read on was clouds, by Roy Spencer. It was an appropriate hypothesis that rests in a knowledge gap (freely admitted by climate scientists - again in the IPCC), but Spencer seemed unable to pinpoint how long-term cloud changes can be decoupled from temperature changes (he hypothesised that ocean/atmospheric processes, like ENSO and PDO, can cause long-term changes in cloud dynamics - but didn't show how that happens). Furthermore, his calculations seem to be irretrievably flawed.

    At the same time, I consider Spencer's work to be appropriate hypothesising on a topic that has substantial uncertainty in climate science.

    Spencer's hypothesis;


    realclimate response;


    I think these two articles in tandem make good reading.

    None of which has been done by much more than hand waving whilst you are asking skeptics to do the science.

    I suggest that you are unaware of the volume of work done on all three above matters. I would recommend that you acquaint yourself with the latest IPCC report. The pdf files at this link


    can be searched on these topics. You will find that the mainstream view of the matters above is based on substantially more than 'hand waving'.

    To be honest, I've come across only one AGW skeptic in my travels that has actually read at least a part of the IPCC report(s). Most make claims about the mainstream view without having read up on it. In the interests of frankness, have you read much of the IPCC report?

    I couldn't quite understand the rest of your post, so I'm not able to comment.

    Greetings from Sydney, Australia.


  • At July 09, 2008 10:53 PM, Anonymous Anonymous said…

    That's just not science. Science is not about consensus it's about data gathering and analyzing it. Not to be sent to IPCC to be modified and then presented.

  • At July 10, 2008 5:02 AM, Anonymous Anonymous said…

    How exactly are you proving your point when you admit (emphasis mine)...

    "yes, the temperature moved FIRST"

    and you make hidden conciliatory statements like...

    "for the MAJORITY of that time"

    and then you freely admit...

    "CO2 did not trigger the warmings"

    and then you rely on the lamest of hollow arguments...

    "according to climate THEORY and model EXPERIMENTS"

    and then you stumble back to close with complete opinion and conjecture...

    "we may well" and "The likely candidates"

    Anyone with a brain will read your post and laugh - it's pathetic and you've actually done nothing but strengthen the skeptics argument.

  • At July 11, 2008 10:56 PM, Anonymous Anonymous said…

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