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Climate Hustle

Global warming theory isn't falsifiable

What the science says...

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Global warming theory isn't falsifiable


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Comments 51 to 83 out of 83:

  1. "Nero fiddled", and sure enough, I hear the sound of violins.

    Are the glaciers melting?

    It's taken 150 years to ignorantly get ourselves into this peril: it will take 150 years of directed response to reverse the trend:  isn't it time to move into "response" and let the late-adapters fogure it out?

  2. Re: John Hartz's call for volunteers to write up an OP, I'd be willing to give it a shot, if no one with better scientific qualifications (read: any qualifications at all) steps up.

  3. I'm game to at least review drafts of an OP.  I might be able to provide some raw material, too.  You can tell what my perspective is from reading my comments on this thread.

  4. As with Tom, ditto for me. My post @41 has one possible outline that could be considerably expanded.


    [DB] Multiple authors can be credited, for those wishing to help write the post.

  5. The public may rightfully use scientific tools such as falsifiability to analyse the legitimacy of climate science arguments that are presented in summarised, or superficial form, (websites such as this one, Wikipedia, media articles, government policy statements etc). This communication needs to be beyond reproach. I don’t feel that this required level of "trust" is presently met regarding falsifiability. Using a benchmark of unfalsifiable pseudoscience such as the statement "Ghost are real and only people who believe in ghosts can see them", I find the following problematic:

    - Whenever temperature records are adjusted or otherwise shown to be previously flawed, the data has logically been proven to be unreliable. However, as long the new data supports the hypothesis, the original failure/limitation of the scientific method is ignored.

    - The definitive scientific meaning of the statement “The anthropogenic global warming signal has definitely emerged” is "flexible" in terms of its communication to the public in relation to natural variability.

    - A reliance on a multitude of complex and easily adjustable models.

    - Contradictory statements about the significance of short term/decadal temperature trends and the reasons for them. (Eg. Late 20th century temperature record versus 21st century temperature record).

    - Noteworthy examples of a perceived reluctance by climate scientists to publicly share all data and methods.

    - Climate scientists who are subject to ad hominem attacks from colleagues only after they dissent from the consensus, not before.

  6. mbarrett @55, it is hard to disagree that the "...public may rightfully use scientific tools such as falsifiability to analyse the legitimacy of climate science arguments...".  You appear, however, to not know what is meant by that - and demonstrate it immediately by continuing your claim, specifying that that right extends to analyzing " the legitimacy of climate science arguments that are presented in summarised, or superficial form".

    Certainly the public has a right to check the accuracy and adequacy of summary presentations of science, but that is not a process of falsification.  Checking the accuracy of reports of science involves comparisons of the report to the original science, ie, the scientific papers and review articles on which the reports are based.  Further, while the public has the right to do that, only those of the public sufficiently scientifically literate to read and comprehend the original papers are able to do it.  Asserting the public's right to do something without asserting also the public's responsibility to make sure they are sufficiently able to do it is mere demagoguery.

    As noted, not only does the public have the right to fact check popular articles, they have the right to check the scientific adequacy of the original science - but again the responsibility to be sufficiently informed applies.  Based on hard experience, scientists consider it necessary to get the equivalent of a Bachelor of Science with Honours, and be well on the way to completing a PhD to reach that level of qualification.  While we need not expect the public to go to that extent, we should at least expect them to be approaching that level of expertise before they comment.  The sad fact, however, is that most comments by so-called "skeptics" here and across the net come from people who do not even understand the theory they purport to falsify.  Sadly, this cartoon fairly represents the current state of public debate on global warming:

    Finally, as we are talking about falsification, before publicly commenting on whether or not a theory is falsified, people should at least understand what is meant by "falsification".  At a minimum they should know the difference between universal and existential statements (with the former being falsifiable but not verifiable, and the later being verifiable and not falsifiable); between methodological and naive falsification; and also understand the Duhem-Quinne thesis, and its relevance to falsification.  Lacking that understanding, attempts at falsification reduce to crass cherry picking of straw man theories.

    Your list of problematic features suggests you do not have that level of understanding.  As the topic here (even with the absent OP) is falsification, and given your introduction, it appears that you consider "problematic" features as being those that indicate the underlying theory to be either falsified, or unfalsifiable - where the latter indicates it has no empirical content.  Yet you list features (purported ad hominen attacks, "perceived" reluctance to share data and methods, supposed reliance on models, etc, which have no bearing on whether or not a theory is falsifiable.  I get the distinct impression that you have merely used the topic here to introduce vague claims without justification in a topic where defence of those claims will be "off topic", so that you will not have to defend them.

    The most bizzare claim you make is that the reliance on models is problematic with regard to falsification.  In fact, a theory is just a set of propositions closed under implication.  A model is a set of propositions closed under implication with particular initial and boundary conditions.  A model, therefore, takes a theory and shows the empirical implications of that theory under certain empirical conditions.  Models, are, therefore, the means of generating falsifiable content from a theory.  With the understanding that mathematically (and logically), a model is a set of equations plus initial and boundary values, models need not be computer models.  Further, no theory that is not presented as a model (ie, the equations plus conditions) has falsifiable content.

    If you truly understood science and falsification, you would, as I, not find the use of models in climate science as problematic.  Rather, you would find the almost complete lack of models from skeptics concerning.  It means that in scientific terms, they have no theory.  Just some words to act a rallying cries. (There are, of course, a few exceptions to this generalization.)

  7. Thank you for the interesting reply Tom. I am especially taken by your strong reaction to my comment about models:

    The most bizzare claim you make is that the reliance on models is problematic with regard to falsification.

    I had always assumed that proponents of falsifiability were specifically thinking of the drawbacks of "induction heavy" methods, such as models, especially when, as in the case of climate science, they will only be proven correct when we're all dead. It seems to me a climate science model is not sufficiently falsifiable for many years. I'd be interested to know what other posters think. 


    [JH] Plese note that the all-vounterr SkS author team is constructing a time travel machine a la H.G. Wells.

  8. mbarrett @57, I'm so sorry.  I had forgotten that Popper's falsificationsim demanded falsification within a certain time limit.  So good to learn that theories that the Sun will eventually become a red giant are unscientific because we will not be around to falsify them /sarc

    (As an aside, the climate models have not been falsified yet, and may not be falsified when we are long dead - but could have been falsified on their first production.  Your conflation of "has not been falsified" with "is falsifiable" is noted, however.  I draw your attention once more to the pointlessness of having a right to examine whether or not climate science is falsified, coupled with a complete lack of ability to deal with the issues involved. 

  9. I don't think its pointless. In fact, the lack of expertise of, well, everyone who is not an expert, is entirely the point, (remember the objective of this website). There are two ways falsifiability is valid in climate change science. One is the implicit falsifiability of a given theory or research paper, (obviously the rightful point of this page), the other is the value the scientific community attaches to falsifiability as a tool of the non expert to critique their scientific standards. Or to put it another way, falsification is impossible if one is hindered from falsifying. Popper's political opinions, it seems to me, explain the value he attached to falsifiability. If I may make one criticism of your comments, it's that perhaps don't make it clear that you understand a perfectly excellent scientific theory, such as AGW, is not necessarily a showroom example of falsifiability.

  10. mbarret models are not necessarily inductive, I could make a mathematical model of a double pendulum (a chaotic system) based on physical laws, or a statistical model of the body mass of dinosaurs.  There is a spectrum of model types and GCMs are closer to the double pendulum model than statistical ones.

    The length of time required to falsify a climate model is also no where near as long as you suggest.  A statistically significant cooling over a period of 30 years, during which CO2 had continued to rise and there was no change in otherf forcings which could explain the cooling would consitute a falsification of the models.  Such a test has already been performed and the models were not falsified, but they could have been, which is what makes the theory scientific form a Popperian perspective.

    "Or to put it another way, falsification is impossible if one is hindered from falsifying."

    This is nonsense on stilts.  Climatologists are in no way unusual in their view of falsificationism, and modellers are perfectly happy to talk about the failings of their models. 

    Besides, the models have been falsified, they predict that Arctic sea ice loss will be slower than that we have observed, so much so that it lies outside the spread of the models.   The skeptics don't seem to want to talk about that though ;o)

  11. Dikran Marsupial @60, the models have not been falsified by Arctic Sea Ice extent.  A climate model predicts a very large number of variables.  For any given variable, it may show values with a p value of 0.01 (for instance), but with 20 or more variables predicted, the probability of any one variable showing a p value that low is quite high.  With 20 variables it is 0.1821, which is well above the conventional 0.05 falsification standard.  Climate models, of course, have far more than 20 variables.

    Having said that, if we consider the sea ice modules of climate models in isolation, arguably they have been falsified.  Arguably because, according to Popper, whether or not a theory has been falsified is always a matter of convention.  (Indeed, given the Duhem-Quine thesis, that falsifications are matters of convention follows by necessity.)   As such they may need to be replaced with better modules, and the climate modelling community and particularly the sea ice extent community are very busy trying to assess to what extent the discrepancy is a statistical fluke, and to what extent their theory needs modification.

    Here, it is necessary to bear in mind Lakatos statement that all research programs "... grow in a permanent ocean of anomalies", that "All theories, in this sense, are born refuted and die refuted".  As a result of this, in his opinion, the important feature of science is not falsifiability, but the determination to eliminate anomalies only by growing the emperical content of the theory - something which is very evident in climate scientists and notably absent from their critics (who tend to ignore anomalies in their own, very stunted theories).

    For what it is worth, Lakatos was a student of Popper's, and considered by Popper to better understand Popper's theory of falsification than any person other then himself - until that is, Lakatos showed signs of independent thought.

  12. mbarrett @59:

    "I don't think its pointless. In fact, the lack of expertise of, well, everyone who is not an expert, is entirely the point, (remember the objective of this website)."

    You should learn, and remember Werner Heisenberg's definition of an expert:

    "An expert is someone who knows some of the worst mistakes that can be made in his subject, and how to avoid them."

    There are two corrollaries:

    1)  Mistakes made by experts tend to be interesting, in the sense that you have to learn something new (expand the emperical content of the theory) to refute them; and (more relevant to this discussion)

    2)  Non-experts do not know all the basic mistakes in a theory, and will tend to repeat them.

    Arrogant non-experts repeat them ad nauseum.

    You can see the efforts of (often arrogant) non-experts trying to "falsify" climate science by repeating basic mistakes, often mistakes refuted decades, and in some cases centuries ago, in most of the comment threads on SkS.  An informative introduction to the arrogance of non-experts can be found by reading the comments in the 2nd Law of Thermodynamics thread.

    In any event, there is a clear disparity between experts and non-experts.  The criticisms of non-experts will almost inevitably be uninteresting - mere repetitions of mistakes that have been refuted beforehand.  Because they are not experts, they do not know any better.  In order to effectively criticize the theory you have to be able to distinguish between the interesting criticisms (those which are not mere repetitions of past mistakes), and the uninteresting repetition of basic mistakes - and to do that you need to be familiar enough with the literature to know of those past occurences of the basic mistakes and the papers that responded to those past mistakes, and refuted them.

    In contrast, when responding to basic mistakes, you do not need to know what was wrong with all basic mistakes, but only that to which you are responding.  Likewise, to understand the basic concepts of the theory, you do not need to be expert.  You should, however, recognize that understanding the basic concepts (which takes a few hours study) does not provide the platform for criticizing the theory that comes from many years of intensive study as found in experts.

    As an anology, I understand the basic principles of carburetion.  That does not mean I am able to effectively criticize the design of any modern carburettor or fuel injection system.  I would be a fool to think my limited knowledge gave me that ability.  But that in know way means I am unable to show the errors by bigger fools who think carburettors would be improved by placing an impermiable membrain across the barrel, or by removing the jets.  Sadly, most inexpert criticisms of climate science show little more sophistication or cogency than those the analogy (I again refer you to the 2nd law of thermodynamics thread if you don't believe me).

    For some strange reason, most people are willing to respect expert knowledge in nearly all topics.  But they seem to think that expert knowledge ceases to exist if the topic is relevant to public policy.  They seem to think that just because the refutation of their particular objection was not included in a basic presentation of climate science (or just as often, included but simply not understood by them), that therefore the refutation does not exist and that they have refuted with a few moments of uninformed thought the work of thousands of experts.  They are deluding themselves, and you do them no favour by pretending otherwise.

    This does not mean that they should not attempt to refute climate science.  In fact I encourage them to do so.  But to do so they must put in the effort to become genuinely expert.


    [JH] How about transforming this very informative comment into a SkS article?

  13. mbarrett:

    Your claim that Climate Science is falsifiable only after we are dead is false on its face.  In 1896 Arrhenius predicted that the climate sensitivity was 4.5C/doubling of CO2.  That number (calculated with a pencil) is still within the IPCC accepted range (although it is at the high end of the accepted range).  His calculation has been validated by observations since then.  Skeptics ignore the history of climate science when they say the science is not falsifiable.

    Likewise, in 1989 James Hansen and denier Richard Lindzen testified before congress.  Hansen asserted that the warming signal could be observed while Lindzen testified that it was not warming.  The observations currently are "unequivical" that Hansen was correct and Lindzen's position has been falsified.   Lindzen has proposed many skeptical theories over the past 40 years.  All have been decisively falsified.  He will be remembered as an abject failure and a hinderance to determination of the facts about Climate Science.

    Numerous other examples exist where Climate Science has correctly predicted changes in advance.  The recent National Academy of Science and American Association for the Advancement of Science Reports contain myriad examples of effects predicted decades to centuries ago that are now measured.  Skeptical claims that changes will be small have been decisively falsified.  

    The question before us now, that scientists are currently debating, is will the changes be catastrophic or just really bad?  How long will you live?  If the drought currently occuring in Texas and Caifornia turns out to be the first major (USA) agricultural hit from AGW we will know if 5-10 years.  I expect to live about 30 years.  That is enough to see big changes from BAU.

    Your claim of "It seems to me a climate science model is not sufficiently falsifiable for many years." is only true if you ignore all the evicence that has already been collected.  Of course if your standard is that anything learned before today doesn't count, it will be longer before AGW is proven again.

  14. Tom, there is a distinction between the models being falsified (which they are by the sea ice extent, where the observations are far enough from the models to be falsified at a sufficently low alpha for us to be confident that they do get sea ice extent wrong) and the theory underpinning the models.  mbarret was talking about the falsification of the models.  It isn't a big deal that the models are falsified as GEP Box's famous quote tells us that all models are wrong (but some are useful).  If we gather enough data all models can be shown to be wrong, however that doesn't mean the underlying theory is wrong, just that some particular refinement or detail is missing from the model.

    However, my point remains, even without the models, the scenario I mentioned would falsify the theory within a reasonable timeframe, so mbarret is still wrong!

  15. Dikran Marsupial @64, here is the latest model/observation comparison from Real Climate for September SIE:


    Looking closely we see one or possibly two values below two StDevs of the multi model mean.  We see a further six (seven counting 2013 more than one but less than two StDev from the multi model mean.  Given 34 observations (35 including 2013), that yields a p-value well above 0.05 even though the p-value for one (possibly two) observations by itself is less than 0.05.  If the observations were randomly clustered, therefore, the models would not yet have been falsified.  That is because, as you well know, the probabiliy of a particular event occuring increases with the number of trials.

    Of course, the events are not randomly clustered.  They show a distinct trend, and an analysis of trends may show that with regard to trends the observations have a p value less than 0.05 relative to distribution of the models.  Unfortunately, I don't know that as I have not seen that analysis.  If it is, by convention the sea ice modules for C-MIP3 might be considered falsified.  Of course, as you know, the standard that data with a p value less than 0.05 falsifies a model is a fairly arbitrary convention.

    My point, however, is that the potential falsification of the sea ice models does not equate to a falsification of O-A General Circulation Models of which they are components.  For the GCMs, the sea ice modules are just one component.  Because the models have statistical output, a p value less than 0.05 for one module does not mean a p value less than 0.05 for the total output of the GCM - and it is only the latter that would falsify the GCM (even under the standard convention).  That is because even if the models were entirely correct, over a number of predicted observations, some would be expected to have p values less than 0.05 just by chance.

    As an aside, at Real Climate, Gavin wrote:

    "Sea ice changes this year were again very dramatic, with the Arctic September minimum destroying the previous records in all the data products. Updating the Stroeve et al. (2007)(pdf) analysis (courtesy of Marika Holland) using the NSIDC data we can see that the Arctic continues to melt faster than any of the AR4/CMIP3 models predicted. This is no longer so true for the CMIP5 models, but those comparisons will need to wait for another day (Stroeve et al, 2012)."

    (My emphasis)

    Consulting Fig 9.24 in AR5 WG1 Ch9, we see that the models are not falsified with regard to Sept sea ice extent (which is not the same as saying they perform well).  Apparently, however, they now have a problem with Arctic winter sea ice extent.

  16. We can falsify the claim that our CO2 emissions will double the concentration of CO2 in the atmosphere in the next one hundred years using the fact that cosmic rays create roughly 8 kg of carbon-14 every years. See here:

  17. Kevan. Here is a comment I tried unsuccessfully to post on your blog



    I am new to your blog and I have just read through your series on the Carbon Cycle. Unfortunately your analysis misses some key issues and is quite wrong.

    What you argue reflects the understanding of the oceans role in CO2 balance that stood during the 1st half of the 20th century. Even as late as the beginning of the 50's this was still the official view of the American Meteorological Society. However advances in oceanography and the understanding of ocean chemistry in the next few years overturned this. Your analysis does not reflect that.

    Firstly, Oceanography understands ocean circulation quite well. The top 100 meters of so is very well and rapidly mixed through wave and wind actions. Below this the ocean is highly vertically stratified. Importantly this highly stratified ocean only allows extremely slow diffusion of any chemical, including dissolved CO2 for example, vertically. This has been confirmed by chemical tracer studies for example. By diffusion alone, major changes between the surface and the abyss would take millenia. However major vertical ocean currents in some regions mix the ocean more rapidly than this, but still on timescales of many centuries. It is said that a water molecule sinking to the sea floor in the North Atlantic wont return there for 1000 years. These two processes define a characteristic timescale for propagating changes from the surface to the depths. Changes on timescales of decades only impact the upper ocean.

    So your simple model of 'a reservoir' is unphysical. The proportion of the ocean engaged with the surface is dependent on the timescale of the event. The 'size' of your reservoir is a time dependent value.

    Secondly, most of your discussion portays the carbon in the ocean as all CO2. In one post you do mention it as being carbonate, but don't follow through with that concept.

    The carbon content of the oceans, excluding biomass, is referred to as Dissolved Inorganic Carbon (DIC). It exists in an equilibrium between 4 states. Dissolved CO2 (CO2aqueous), Carbonic Acid (H2CO3), Bicarbonate ions (HCO3-) and Carbonate ions (CO3--). The balance between these four forms depends on the reaction kinematics of the respective reactions that convert between these forms.

    CO2aqueous + H20 H2CO3 HCO3- + H- CO3— + 2H-

    This link is a Bjerrum plot, showing the proportions of each form present depending on the ph of the water. CO2 & H2CO3 are grouped together. Note the vertical scale is logarithmic. [LINK]

    Notice that most carbon is as Bicarbonate, with 10% Carbonate. CO2/H2CO3 is around than 0.5%. And note also the dependency of these concentration proportions on pH - this is the origin of the problem of Ocean Acidification.

    This is actually more complex than this since ocean pH isn't just governed by the reactions above but other factors such as Boric acid concentrations. The detailed chemistry of this was first worked out in the 50's by Roger Revelle.

    These chemical relations and the kinematics governing them constitute another partitioning of the 'reservoir' - different chemical reservoirs. Carbon as bicarbonate for example is only available to potentially be exchanged with the atmosphere as CO2 when the kinematics allow the reverse reactions to dominate.

    So your hypothetical single reservoir needs to be considered as multiple separate sub-reservoirs separated spatially and temporally, and chemically. Only the surface/CO2 reservoir is engaged in gas exchange with the atmosphere

    Your broader analysis may come to reasonable answers when applied to long enough timescales (multiple centuries) but still can be limited by the chemical constraints. So the long recovery times for a major CO2 increase presented in the scientific literature are based on these factors. Short term surface mixing processes, multi-centenial scale deep ocean mixing timescales and chemical reponses.

    For instance, the truely long term response that recovers CO2 levels is chemical. After ocean mixing has done the maximum possible, there is still a remaining, slow chemical response that achieve the final draw down, on multi-millenial timescales.

    There is one final class of reactions that can occur in the ocean.

    CO3— + Ca++ CaCO3.

    Carbonate reacts with calcium ions and other minerals ions in the oceans to be deposited as things like Calcium Carbonate - Limestone. This is the final equilibration. The Carbon is deposited on the sea floor as rock.

    The response to a major increase in atmospheric CO2 does give a very long timescale for recovery - centuries.


    [RH] Shortened link.

  18. Here is the comment I posted on Kevan's earlier blog post (where it seemed more relevant), which concludes:

    "But the doubling of the carbon-14 concentration by bomb tests amounts to a gigantic experiment upon the atmosphere, and this experiment turns out to be profoundly revealing when it comes to estimating the effect of human CO2 emissions upon the climate."

    Unfortunately carbon-14 from bomb tests tells you almost nothing about the effect of human CO2 emissions upon the climate. This is because the decay of bomb carbon-14 can only tell you about the residence time of carbon in the atmosphere (the average time a particular molecule of CO2 remains in the atmosphere before being transferred to another reservoir) but not the adjustment time (the time taken for atmospheric CO2 to respond to changes in the sources and sinks - essentially the characteristic timescale of the decay of atmospheric CO2 should we cease all anthropogenic emissions today). The residence time for CO2 is not equal to the adjustment time because of the vast exchange fluxes that constantly exchange CO2 between reservoirs, but this is a straight swap, so it doesn't change atmospheric concentrations. 14C has a short residence time, but mostly because it is just being exchanged with 12C and 13C from the oceans and terrestrial biota. This is a somewhat counterintuitive idea that is often misunderstood, which is why I wrote a paper about it,

    Gavin C. Cawley, On the atmospheric residence time of anthropogenically sourced carbon dioxide, Energy & Fuels, volume 25, number 11, pages 5503–5513, September 2011.

    which you can find here:

    preprint here:

    I wrote a blog article about it for SkS, which you can find here:

    The residence time is not controversial, and estimates range from about 4 years to about 20. The adjustment time is much longer 50-200 years for the initial phase, but the decay has a long tail.

  19. Dear Glenn,

    Thank you for your answer. I'm not sure why my site refused your comment, but I apologise for the inconvenience that must have caused you. I will check the comment settings.

    Which of the following facts to you dispute?

    (1) Carbon-14 is produced in the upper atmosphere at roughly 8 kg/yr.

    (2) 1 in 8000 carbon-14 atoms decays every year. Therefore, for equilibrium, there must be roughly 64,000 kg of carbon-14 on Earth.

    (3) There are only 800 kg of carbon-14 in the atmosphere. (800x10^12 kg of carbon in the atmosphere, 1 ppt is carbon-14)

    (4) Somewhere on Earth, other than the atmosphere, there is 63,200 kg of carbon-14.

    (5) Every year, 8 kg of carbon-14 migrate from the atmosphere to wherever the rest of it is.

    (6) Whatever atmospheric carbon-14 does, it does in the company of one trillion atmospheric carbon-12 atoms, because carbon-14 and carbon-12 are chemically identical.

    (6) The concentration of carbon-14 in the deep ocean is 80% of the concentration in the atmosphere. The concentration in the Earth's biomass is 99% of the concentration in the deep ocean.

    If you accept the above observations, I suggest you ask yourself how can 8 kg of carbon-14 move out of the atmosphere every year? 

    As to your suggestion that multiple reservoirs change the picture in a significant way: you are incorrect. Two- and three-reservoir systems are easiy to simulate in an Excel spreadsheet, so if you disagree, please prove me wrong. Or you can consult the Arnold et al. paper linked to below for their proof that the complexity of the reservoir makes not difference to the fundamental behavior of the combination.

    Where does the 8 kg of carbon-14 go? By what chemical process does it get to wherever it goes? Please answer these specific questions.

    Yours, Kevan


    Link updated[GT]

  20. Also, I would greatly appreciate someone checking observations (1) through (7) above. For example, I had to multiply 2.0 carbon-14 atoms per second per centimeter squared by a bunch of numbers to get 7.5 kg/yr for the entire Earth, which I am rounding to 8 kg/yr. What if I'm off by a factor of ten? I have checked and checked, by I could be making the same mistake over and over again. Yours, Kevan

  21. kevanhasemi @69, using the figures provided by this wikipedia article, I calculate the range of the Mass of C14 atoms created annually and globaly to be 6.14-7.04 (median 6.59) Kgs.  However, C14 has an atomic mass of 14, compared to the atomic mass of 12 for atmospheric Carbon on average.  To calculate the rate of transfer of carbon atoms generally from those of C14, you would need to do it on a per particle basis, or apply an adjustment to bring the weighted C14 mass in line to that of C12.  By my calculation, that reduces the C14 weighted mass to 5.65 Kg.  Therefore, at equilibrium, and ignoring radioactive decay, 5.65 Petagrams of Carbon leave the atmosphere, which tells us nothing about the net flux.

    That amount compares to the combined gross flux of 203.3 PgC/annum shown in the IPCC AR5 carbon cycle illustration, or a net flux (excluding that from fossil fuels and volcanoes), of 4.9 PgC/annum:


    That is close enough to the expected figure that there is no evident problem for the figures shown.  The discrepancy can be more than made up for by dillution of atmospheric C14 abundance by the exchange with the ocean, and by volcanic outgassing.

  22. Dear Tom, Thank you very much. For some reason I was worried about that calculation. Looking at the diagram: of order 40,000 Pg carbon interacting with the atmosphere, I agree that's close enough. I think I assumed that the carbon-14 concentration was parts per trillion atomic, not parts per trillion by mass. I will have to check, but if it's by mass, then thank you for pointing out the correction. Yours, Kevan

  23. Dear Tom,

    I missed this earlier. You say "Therefore, at equilibrium, and ignoring radioactive decay, 5.65 Petagrams of Carbon leave the atmosphere, which tells us nothing about the net flux." You are forgetting that a like amount of carbon replaces the 5.65 Pg at equilibrium, and it also contains carbon-14. You need a net transport of 5.65 Pg of carbon-14 out of the atmosphere every year. What is the concentration of carbon-14 in the place that this 5.65 Pg is going to? Suppose it's 0.96 ppt, then the transport is 25 * 5.65 Pg/yr = 140 Pg/yr.

    Yours, Kevan

  24. Corection: "net transport of 5.65 kg of carbon-14", not Pg.

  25. kevanhashemi @73, considering the preindustrial condition in which there is close to equilibrium between CO2 fluxes into and out of the atmosphere, and assuming the relative ratio of C14 in the respective pools as specified by you @69, then a gross flux 28.25 petagrams of carbon per annum (PgC/yr) into the ocean from the atmosphere would carry 32.95 Kgs of C14 with it.  At the same time, a gross flux of 28.25 PgC/yr from ocean to atmosphere would carry 26.36 Kgs of C14 with it.  The net flux would be 6.59 Kgs of C14 from atmosphere to ocean, with zero net flux in CO2.

    This back of the envelope calculation ignores that C14 has a slight bias in its flow from atmosphere to ocean over its flow from ocean to atmosphere (due to its slower mean velocity at a given temperature due to its greater mass), radioactive decay and any net flux in C14 from the atmosphere/biosphere exchange.  It also ignores the fact that, in the prindustrial state, there is a slight bias of outgassing to dissolving of CO2 from the ocean (about 2%), which is compensated by (mostly) soil carbon eroded into the ocean.

    The key point, however, is that the gross flux is approx. 35% of the true value as shown by the IPCC AR5 diagram.  Therefore, the back of the envelope calculation gives us no reason to think the fluxes shown by the IPCC AR5 diagram are underestimates.

    As it happens, the C14 concentration in the surface ocean is approx 95% of that in the atmosphere, not 80%.  Plugging in that value would result in an overestimate from the back of the envelope calculation, but not so large as to call the IPCC figures into question.  If you do want to call them into question you need to take account of the differential flux of C14 due to its increased mass, the influx of low C14 organic matter from soils, the fact that the C14 concentration of the surface ocean varies by location and therefore it matters crucially where the exchanges occur, and all the various complications that were taken into account in the scientific papers on which the AR5 depended in determining its fluxes.

  26. This is an interesting topic that has recently been published on in the Public Understanding of Science journal by David Mercer. His analysis documents how Popper is invoked by those on both sides of the issue, and his analysis seems to be very illustrative of many of the arguments appearing in this thread. If you had not seen it, here's the link:


    [PS] Link fixed. Please learn how to do this yourself with the link tool in the comments editor.

  27. Tom Dayton said: "You are incorrect that falsifiability is "the very definition of science." That is something you would know if you had gotten past introductory science classes in college. (It is sad that such fundamentals of science are inadequately taught at the introductory course level."

    I resent your comment. First of all, it is an ad hominem (and hence should have been deleted), because it clearly implies that PanicBusiness never got past an introductor science class n college. Also, it implies that PanicBusiness was never taught the fundamentals of science.

    Your argument is also fallacious because it asserts that PanicBusiness' statement is wrong without explaining why. Rather, you simply assert that his statement is false, then go on to conclude that he hadn't gotten past introductory science in college. Whether PanicBusiness even has a high school diploma or not is irrelevant. What is relevant are his reasons for claiming that falsifiability is "the very definition of science."

    I assure you that I got well past introductory science course, so I must say that I am offended by your implication because by extension I believe you are also suggesting that I never got past introductory science classes in university or that I do not understand the fundamentals of science. I believe that your ad hominem extends to me because I basically agree that falsifiability is an excellent criteria for differentiating between science and non-science.

    The wordpress article you linked to does not really explain why you are so disdainful of PanicBusiness' idea that falsifiability is "the very definition of science." I disagree that it is "the very definition of science" but your response is just a dismissive ad hominem that doesn't explain or clarify.

    I am also a little disappointed by the "Response" (in green) found within PanicBusiness' comment. I think the idea of falsifiability being crucial for differentiating between science and non-science is well enough know that a source should not be required and it would have been more appropriate to clarify or explain that Karl Popper wasn't suggesting that falsifiability is "the very definition of science itself."

    I am disappointed that Tom's post wasn't deleted because I think it is clearly an ad hominem, but I suspect that it was allowed to stand because PanicBusiness seems to be arguing that the theory of anthropomorphic global warming (AGW) is not scientific.  This appears to me to be a bias in the application of the rules.

    I think PanicBusiness is wrong to say that the AGW theory is unfalsifiable because it clearly makes predictions which are falsifiable.

    In addition, alternative explanations for global warming often make predictions which are simply false, so the AGW theory stands as the best explanation.

    The AGW theory of global warming is falsifiable, hence it meets that very crucial criteria of a scientific hypothesis or theory.  The AGW theory is also the best explanation for global warming.


    [PS] Moderation complaints are always offtopic. Moderating is an onerous task for which we dont always get it right but a lengthy post complaining about comments made more than 2 years ago does not contribute much to the discussion. Your main points are fine.

  28. Synthetic Organic, your post sounds very reasonable, and prompted me to go back and read the thread. In the broad context of the whole thread, there was ample evidence that PanicBusiness had a foolish notion of what science was, how it should proceed, and whether AGW should count as science. The suggestion that he had not got past introductory science classes was, perhaps, ad hominem, but if he did get past those classes he clearly failed to develop a mature understanding of the nature of science.

    Among his comments from 2014 was this: "I personally find it very likely that in the coming five years there will be no significant warming or there will even be significant cooling. If that happens I want the CAGW community to not come up with additional excuses, and hand-waving like it was totally expected."

    In hindsight, he looks especially foolish given the string of record global temperature records that have occurred since he made his prediction. (It's comically ironic, really, that his own worldview was so rapidly falsified.)

    Besides, he was a sock puppet, so all of his posts were tainted with dishonesty. Those who engaged with him probably picked up on that dishonesty, recognised him as a troll, and reacted accordingly.

    I agree it would have been better if the ad hominem elements had been left out. On the other hand, I think the SkS regulars are remarkably patient with folks like PanicBusness. It is not surprising that an ad hominem flavour crept into the thread, given that the regular SkS commentors were dealing with a dishonest fool pedalling a tired denialist meme.

  29. Synthetic Organic @77, it is impossible that falsifiability be "the very definition of science" given that as a criterion, it was not invented till the 1930s in Austria by Karl Popper.  A great deal of what is still considered some of the best science peceded that invention, including the discovery of relativity (special and general) and of quantum mechanics.  That science was carried out by people who had never heard of falsifiability, let alone imagined that "it was the very definition" of the activity they devoted their lives to.

    The key point here is that Popper was just one philosopher of science, who proposed what he considered to be a non-falsifiable methodology of science.  That is, by his own words, his theory of the method of science was not scientific.

    More importantly, his proposed methodology was not agreed to by all, or even most, philosophers of science, and was shown to be methodologically inadequate, and false as a description of the actual methodology of science by his student Imre Lakatos.   That was also shown by Thomas Kuhn, and arguably (although his thesis is far too strong) by Paul Feyerabend.

    There is a lot of confusion on this point, both because many scientists are indifferent philosophers of science (although a rare few are very astute), and because Naive Falsificationism (which Popper also rejected) is often seized upon by pseudoscientists as a criteria to (incorrectly) reject genuine science, and also by disciplines of disputable scientific merit (economics, psychology) in attempts to show that they really are scientific.

  30. That's a great succinct review Tom!

    Applying the strict Popperian criteria of falsifiability in a blanket sense to complex topics like climate change is a common trick of all science skeptics. It's also common trick used by those challenging evolution, who claim that every uncertainty or gap concerning the mechanisms which give rise to new species, adaptation or novel traits should be taken as disproof of decades of research supporting central role of evolution in biology.  

    The other trick is to claim that consensus formed through years of testing and rejecting alternative hypotheses results in an unfalsifiable hypothesis, as if the previous testing never occurred. It's an effective attack (on purely rhetorical grounds) when targeting those unfamiliar with the history of disciplines in question. It plays well in the atmosphere of cultural division that we now see. 

  31. stephen baines @80, thankyou.  I must reject the accolade, however, in that I have not kept up with the last 20 years of philosopy of science, so it is not really a review.  Philosophy Now has this summary of the more recent developments in philosophy of science:

    "The first of these questions is the one with which the likes of Popper and Kuhn wrestled in the past (see previous page), but the debates have moved on. As David Papineau, of King’s College London, remarks, “Nobody works with Popper’s assumptions any more.” These days, the debate is between instrumentalists (not of the musical variety) and realists. Instrumentalists argue that scientific theories do not tell us what the world is really like but they do allow us to make predictions about the world. Scientific theories are instruments for making predictions about the world. Their opponents, who are called realists, believe that scientific theories in fact describe the world and that the ability of a theory to make accurate predictions is an indication that it is successfully describing the world.

    Bas van Fraassen takes the position that what scientists are trying to do is to describe the way the world really is, not merely to make mathematically accurate predictions. However, he agrees with the instrumentalists that one can never know the truth of such claims and can only judge theories on how good they are at making predictions. He calls this position ‘constructive empiricism’."


  32. I have read the comments of this section and I would have to agree with SyntheticOrganic. Moderators should uphold policies to whom it may apply, whether or not they have doubt on AGW being scientific or not. TomDayton has committed an ad hominem attack on PanicBusiness and I have yet to see the moderators so something about it. Be it as it may that it has been years since those comments are made, it is disappointing to see that you don't see this as something that needs action.

    I am here on the count that I am currently writing a paper specifically on falsifiability and would like to read about discussions in the comments to have a broader take on the picture. And yet it seems that you actively stifle those, although given that Panic Business may have been mistaken in saying that falsification is the ultimate definition of science, who are of a different position than what you and the majority's position. For a site called you don't seem to have a very friendly attitude towards those would be skeptics, even if they may possibly be mistaken.

    I expect this comment to be either deleted after it has been read or given that green box with the comment in saying that my comment is of topic. This is again I think is also problematic. How else are we, the commenters, suppose to give our opinions on how you handle comments if you classify those such comments as off topic?

    Again do what you will with this comment, I only hope that I have at least made a point.


    [PS] Moderation complaints are always offtopic. If you dont like our policy, please go somewhere else. What the moderators here do have is a very low tolerance of sloganeering of the type PanicBusiness was indulging in. Discussions around science and evidence are always welcome as are questions from people interested in learning more or improving understanding. It is does not pretend to be a site for general discussion - other places do that better - and certainly does not intend to provide an echo chamber for unsubstantiated sloganeering from pseudo-skeptics who have not the slightest interest in learning anything. This is a site for true skeptics (like scientists), not pseudo-skeptics who are "skeptical" about anything that challenges their a priori beliefs and unskeptical about utter nonsense that think supports it.

  33. @Celestial Teapot

    In addition to the mod's response to you, the unlamented PanicBusiness was one of many fake-accounts run by the same individual in an attempt to spam this venue.  Those who have genuine interest in expanding their understanding of the science in question would have no need to resort to such subterfuge.


    But then, you already knew that.

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