Mass Balance

I once again managed to get involved in a discussion on Judith Curry’s blog about the rise in atmospheric CO2. This time was slightly better than it has been in the past, as most seemed to at least agree that the rise was anthropogenic. The dispute seemed to be as to whether or not a particular line of evidence was conclusive or not. Let’s clarify something first, though. There are many lines of evidence indicating that the rise in atmospheric CO2 is anthropogenic; this is not really in dispute.

However, a particularly elegant way to illustrate that the rise is anthropogenic (which Dikran Marsupial used during the discussion on Climate Etc.) is to simply consider mass balance. If dC is the rise in atmospheric CO2, Ea is the anthropogenic emissions, En is the natural emissions, and Un is the natural uptake, then

dC = Ea + En - Un,

which we can rewrite as

dC - Ea = En - Un.

The rise in atmospheric CO2 is smaller than our emissions, so the left-hand side is negative. Therefore, the right hand side is negative, nature is net sink, and therefore cannot be the source.

However, some were arguing that this simple mass balance argument does not preclude the possibility that some component of nature could be a net source. Okay, but we can go a bit deeper and consider the different components of the system. We have the oceans (which both releases and absorbs CO2) we have the biosphere (which both releases and absorbs CO2) we have the lithosphere (which releases CO2 via volcanic activity and absorbs CO2 via the slow carbon cycle) and we have fossil fuels, which we burn to release CO2 (there is no relevant anthropogenic sink).

Well, the oceans are taking in more CO2 than they release, the biosphere is taking in more CO2 than it releases, and the lithosphere is – we think – roughly in balance, with volcanoes releasing as much CO2 as is being absorbed via the slow carbon cycle. What’s left? Us; the release of CO2 via the burning of fossil fuels. Therefore, the rise in atmospheric CO2 is anthropogenic.

However, I don’t think the above extension is really necessary. If a component of nature could be, or has been, a net source of atmospheric CO2 that would imply a couple of things. There should have been a time when atmospheric CO2 rose faster than our emissions, and – similarly – there should have been a time when atmospheric CO2 would have continued rising were we to stop all our emissions. I don’t think either of these is true. I think atmospheric CO2 has always risen more slowly than our emissions and, if we were to stop emitting, concentrations would drop, not rise. Hence, it seems that the basic mass balance argument is sufficient to show that nature cannot be a source. Even if one component of the natural system is a net source, that would simply imply that other parts are an even bigger sink, so that – overall – nature is a net sink.

There is, however, one possibility. What about, for example, the conditions today being such that nature would be a source were we never to have emitted CO2. Well, we do know that there is a relationship between temperature and atmospheric CO2. If the temperatures had risen in the absence of our emissions, we would expect atmospheric CO2 to rise by between 10 and 20 ppm. One might, therefore, argue that a small part of the rise in atmospheric CO2 is natural and due to the rise in temperature. However, this is a bit of a cheat, given that the rise in temperature is mostly a consequence of our emissions anyway. Also, given our emissions, the concurrent rise in temperature really acts to slightly reduce the uptake of anthropogenic CO2; nature is still a net sink.

This, however, does lead to an interesting issue. As we continue to warm, we expect the uptake by the natural sinks to decrease; the ocean uptake being constrained by Henry’s Law, and the biosphere being constrained by nutrient availability. However, we don’t expect either to ever become a net source of atmospheric CO2. It is, however, quite possible that other natural sources may start to operate, such as permafrost release. These would then be a net source of atmospheric CO2. However, they would be feedback responses to the warming that will be largely a consequence of our emissions (assuming we do continue to emit CO2), hence to suggest that this would mean that nature has somehow become a net source would seem rather disingenuous.

So, as far as I can tell, the mass balance argument pretty conclusively shows that nature cannot be a source and, hence, that the rise is almost certainly anthropogenic. Of course, there are plenty of other lines of evidence, so we certainly don’t need to simply rely on the mass balance argument, but I think the basic mass balance argument is still sufficient precludes nature being a source.

Advertisements
This entry was posted in Climate change, ClimateBall, Global warming, Judith Curry, Science and tagged , , , , , . Bookmark the permalink.

302 Responses to Mass Balance

  1. John Hartz says:

    Although I am by no means an expert on these matters, I believe you are, in balance, correct.

  2. RickA says:

    I agree that the rise in dC is anthro.

    It is my understanding that Ea is about 10gT and Un is about 6GT, leaving about 4gT for dC.

    Even if this is wrong – just use the numbers as an example.

    So we emit 10, natural sinks take up 6 and leave 4 behind in the atmosphere – so far so good.

    However, isn’t it true that Un used to be smaller – say 4gT.

    So the delta Un has increased.

    It is my understanding that this increase in sink uptake is caused by the increased pressure of dC – the higher the number the more CO2 pushed into the sinks.

    Where I am a little confused on attribution is whether the change in Un is anthro or not.

    It seems Anthro to me because but for the increased pressure created by our emissions – the natural sinks wouldn’t have increased due to the extra CO2 we put into the atmosphere.

    This issue doesn’t really matter when dC is going up – but what will happen when dC starts going down (if it ever does)?

    Eventually, Un will drop as the pressure drops.

    Will we call that negative delta Un anthro or nature?

    Nature is helping us now by taking quite a bit of our emissions out of the atmosphere.

    However, in a world in which our emissions decrease, year over year, nature will be hurting us, by taking less CO2 out of the atmosphere – and I am having a hard time wrapping my brain around whether this will be blamed on people or not.

    I am fine either way – it is just that we have to be consistent.

    Any thoughts?

  3. Also, as Prof. David Mackay points out in his book ‘Sustainable Energy – without the hot air”, the observed rise in CO2 concentration is nicely in line with what you’d expect from human emissions.

    Given that 127 part per million (ppm) of CO2 in the atmosphere equates to 1000 GtCO2, and also that roughly 2000 GtCO2 are estimated to have been emitted from the start of the industrial revolution to now, and assuming very roughly that 50% this figure has stayed in the atmosphere, then 1000 GtCO2 then equates to 127 ppm added to the atmosphere on top of the pre-industrial 280 ppm. Namely, 407 ppm (roughly) in total, so in the right ballpark (we were at 400 ppm in 2015). It is also worth looking up the specific chapter within the IPCC AR5 dealing with “Carbon and other Biogeochemical Cycles”.

    Another approach is to take Mackay’s average of 5 tCO2 per person per annum x 7 billion people = 30 Gt CO2 per annum x 127ppm/1000 x 50% ~= 2ppm per annum approx. The 5 tCO2 is based on a bottom up figure of consumption, energy usage, share of transport, etc. (between the extremes 20+ tCO2 in North America and 3 tCO2 in Asia) … [Aside: a recent Oxfam report shows that the disparity between rich and poor exists within each country so the most extreme household in US is responsible for 50tCO2 per annum]

    There are several other ways to get the number e.g. the National Grid data for UK on total electricity supply, etc. etc. then apply the percentage of FF sources then assume percentage of electricity in CO2 output.

    The all come out in the same area.

    For me, that clear link between our energy use / consumption/ industry/ travel, and our CO2 emissions is a transparent method for nailing the human link.

    But on the question of the balance, it is worth stressing that for 1000 years pre-industrial, the CO2 level in atmosphere was stable at 280 ppm, despite the large flows in the short-term carbon cycle. That reflects an exquisite balance. Our emissions have upset that balance. Our current 400ppm is incontrovertibly due to man-made emissions.

    So please excuse me if I am puzzled at why we would seek to engage on a balance question, to derive the sign of the man-made contribution, which is now rising above 2ppm per annum, with no indication yet of a declining.

  4. Eli Rabett says:

    You have to be very careful about using Henry’s law because inorganic carbon in the oceans is governed by equilibria with carbonate and hydrogen carbonate ions . Effing physicists.

  5. Eli,
    Yes, you’re quite right. I was over-simplifying. However, we don’t expect the oceans to become a net source.

    I actually wrote a code to do that whole process and was going to write a blog post about it, but I’ve forgotten how it works. Chemistry is difficult 🙂

  6. RickA,
    I don’t really know what you’re getting at. If dC - Ea is negative, nature is a sink.

    Richard,

    So please excuse me if I am puzzled at why we would seek to engage on a balance question, to derive the sign of the man-made contribution, which is now rising above 2ppm per annum, with no indication yet of a declining.

    This was mainly motivated by a length exchange on Climate Etc. That’s really all. You’re quite right that there are plenty of other arguments as to why the rise is anthropogenic.

  7. RickA says:

    Well I understand that nature is a sink.

    But the change in the amount that nature is a sink seems caused by our increased CO2 emissions.

    Lets turn it around.

    Say we suck 4gT out of the atmosphere (dC = 4) and only emit 2gT (Ea = 2) (4 – 2) = 2, which is positive.

    Will you then merely say well nature is a source?

    Do humans get no credit for pulling down dC – we give the credit to nature?

    That is what I am getting at.

    It is an attribution question – and it seems a bit fuzzy to me.

  8. RickA,
    If we start sucking out of the atmosphere, then we’d need to modify the equation because we have an anthropogenic sink. So, it would become

    dC = Ea - Ua + En - Un.

    Really, you would then have Ea = 2 and Ua = 4, so we would be a net sink.

  9. Eli,
    You had a post that linked to a site that did the whole ocean chemisty/Henry’s Law calculation, but I can’t seem to find it.

  10. RickA says:

    Yes – I agree the mass balance equation needs a term for Ua.

    But why cannot the increase in sink over and above Un, caused by our increased emissions be considered Ua presently?

    It seems to me that if humans get the blame for the increase in Ea and dC, they should get the credit for the Ua (which in my hypo I am giving 100% of the increase in Un over to Ua).

  11. RickA,

    But why cannot the increase in sink over and above Un, caused by our increased emissions be considered Ua presently?

    I don’t really understand what you mean. Are you suggesting that we take credit for the fact that the natural sinks take up some of our emissions? If so, I can’t see why.

  12. RickA says:

    ATTP:

    I don’t see it as nature taking up some of our emissions.

    I see it as us pushing some of our emissions into the natural sinks.

    But for our increased emissions of CO2, the natural sinks would not be taking up more CO2.

  13. Mike McClory says:

    There’s also supporting evidence from isotopic analysis of the carbon in the atmosphere. This demonstrates that the additional CO is primarily from fossil fuel consumption. SkS have a page showing the different lines of evidence (http://www.skepticalscience.com/co2-increase-is-natural-not-human-caused.htm).

    They use an approach similar to yours, but also mention the different responses of the CO2 curve and the temperature curve (if CO2 concentration was rapidly responsive to elevated temperature, then the CO2 curve should be more erratic). But burning fossil fuels reduces the concentration of C14 compared to C12 / C13.

    On top of that there is the decrease in O2 concentration indicating that the CO2 changes are related to fossil fuel consumption (http://scrippso2.ucsd.edu/)

  14. RickA,

    I see it as us pushing some of our emissions into the natural sinks.

    But for our increased emissions of CO2, the natural sinks would not be taking up more CO2.

    This is brilliant. I really don’t know how to respond to this.

    Mike,
    Yes, there is indeed other lines of evidence. The link in the first paragraph was to another Skeptical Science post showing the list of reasons why it is consistent with being anthropogenic, including the isotopes.

  15. Brandon Gates says:

    ATTP,

    This is brilliant. I really don’t know how to respond to this.

    I suggest taking a long, deep draught of something containing a rather high concentration of ethanol.

  16. Here’s the argument, as far as I can reconstruct it (DM can correct me if I’m wrong):

    (0) What governs the rise in atmospheric CO2 is the difference between emissions and uptake; while there is a large exchange flux that is constantly swapping CO2 from the atmosphere with CO2 from the oceans and terrestrial biota, the exchange is a straight swap and has no effect whatsoever on atmospheric CO2 levels.

    (1) Natural uptake is the difference between natural uptake and natural emissions that governs the natural effect on atmospheric CO2.

    (2) Anthropogenic uptake is essentially zero,

    (3) The annual rise in atmospheric CO2 has been smaller than the volume of anthropogenic emissions (fossil fuel and land use) every year for the last 50 years.

    (4) If the environment were a net carbon source, the annual rise in atmospheric CO2 would be greater than anthropogenic emissions, not less.

    (5) Mass conserves itself; objects are permanent; field theory (in which we find additivity) rocks.

    (6) As a whole, the natural environment is therefore a net carbon sink OPPOSING the rise in atmospheric concentrations, not causing it; this is true regardless of the behaviour of individual fluxes.

    (7) As a whole, the natural environment is not the cause of the observed rise in atmospheric concentrations.

    (8) Anyone who’d dispute (6) or (7) needs to explain (3).

    Anyone who wants to dispute the validity of DM’s argument needs to pick at least one number.

    ***

    This is my reconstruction of the 26 comments by DM on this thread:

    http://judithcurry.com/2011/08/04/carbon-cycle-questions

    I only added object permanence and field theory to hint at the fact that this argument could not be parsed by agents who are less than 8 years old.

    This isn’t DM’s argument alone – as he himself says, it was in WG1 and appeared in numerous papers on the carbon cycle.

    ***

    This comment is a second version of that comment:

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760546

  17. > But for our increased emissions of CO2, the natural sinks would not be taking up more CO2.

    Perhaps Mother Nature hired a doorman to reject aCO2 and push CO2 into her club, club that she named The Sink.

    But what if I told you CO2 created its own sink?

  18. Who’s arguing that nature is net source? Nature being net sink doesn’t say anything about the cause of the change (dC).

    dC = Ea + En – Un

    1) If one argues that all of the change is caused by Ea, then without any human emissions (Ea = 0), En = Un and dC = 0. So, nature being net sink is caused by human emissions, without them, obviously, dC = 0 and En – Un = 0.

    2) If one argues that all of the change is caused by nature (En – Un), then without human emissions (Ea = 0) dC is still the same as with them. Nature would be net source and dC would be the same with or without Ea.

  19. > Nature being net sink doesn’t say anything about the cause of the change (dC).

    Incorrect: it says it can’t be Nature.

    ***

    > without any human emissions (Ea = 0), En = Un and dC = 0

    This would imply two things: (a) Nature could never change the rate of CO2; (b) the CO2 rate would never change.

    ***

    > [N]ature being net sink is caused by human emissions

    I’d rather say it follows from the fact that dC changes.

    ***

    > If one argues that all of the change is caused by nature (En – Un) […]

    one might have a better chance arguing that the Moon is made of cheese, unless one’s concept of nature encompasses just about anything possible.

  20. Brandon Gates says:

    Willard,

    one might have a better chance arguing that the Moon is made of cheese, unless one’s concept of nature encompasses just about anything possible.

    Parse this: https://archive.is/U8qfk

    Gunga Din: So Winter Storm Judas is proof of CAGWarming/Cooling?

    me: No. It’s not inconsistent with global warming irrespective of cause.

    Phil R: It’s “not inconsistent” with the moon being made of bleu cheese. So, what’s your point? wetterdryerfreezinghotflooddroughtwinterstormhurricane-nohurricane is “not inconsistent with global warming.” THAT’s the problem. if the hypothesis includes everything and everything is “not inconsistent” with it, then the hypothesis, and your statement, is meaningless and irrelevant

  21. izen says:

    How much of the observed warming is caused by human emissions?

    Is it legitimate to claim that 200% of the atmospheric rise in CO2 is anthropogenic? As with the rise in temperature, ‘natural’ processes have negated some of the total impact of the anthro influence.

    Paleoclimate indicates that the carbon cycle without anthro-emissions has a much smaller and slower sink/source imbalance. CO2 rises and falls more slowly and much less over the last ~3million years.

    The large sink capacity of the carbon cycle when confronted by the fossil fuel emissions is a welcome elasticity of extra capacity. But that increased ability to sink emissions is a negative feedback caused by the rapid addition of CO2 to the atmosphere.

    While there is no argument from measurements that the carbon cycle is acting as a net sink for the rising atmospheric CO2 faction, the changed response of the ‘natural’ cycle could include a increase in natural emissions (permafrost, weathering), balanced by an increase in the activity of carbon sinks that is significantly larger than anthropogenic emissions, but invisible in the final balance because the increased turnover of the carbon cycle in response to the human CO2 emissions cancel.

    So human emissions could be causing 50% of the observed rise, having triggered an increase in emissions from natural processes twice as large as anthropogenic sources and an increase in sinks 250% greater than human emissions.
    😕

  22. > if the hypothesis includes everything and everything is “not inconsistent” with it […]

    That AGW is not inconsistent with opposite weather events only means that weather is not climate.

    Here would be 10 ways to falsify AGW:

    https://ourchangingclimate.wordpress.com/2014/02/17/is-climate-science-falsifiable/

    Here’s another example of a falsifiable claim:

    The ‘hiatus’ will continue at least another decade.

    http://judithcurry.com/2014/03/04/causes-and-implications-of-the-pause/

    Vintage 2014.

  23. Tom Curtis says:

    Imagine an alternate world in which the rapidly expanding world economy is driven by fossil fuels. Coincidently, at the the same time, pCO2 is rapidly rising in the atmosphere, with emission rates and rates of increase in atmospheric CO2 matching those in our world over the last 150 odd years. A certain Professor X runs the mass balance argument and concludes that the burning of fossil fuels is the cause of the rise in pCO2. Another professor, Professor Y, disagrees. Professor Y runs a series of experiments.

    First, he connects two air tight containers with a tap. In the first container he places a volume of distilled water and ordinary atmosphere, while in the second container he places various quantities of pure CO2. He releases the gas from the second container into the first, while maintaining constant temperature, measuring the pCO2 while he does so. He reports the pCO2 when it reaches equilibrium, determined as the point where it remains constant for a given period. He does this across a range of temperatures for the first container, and with distilled water, rain water, sea water and distilled water with salt added to a range of salinities.

    Across all these experiments, Professor Y finds that pCO2 after equilibrium is always the same for a given solvent and for a given temperature, regardless of the quantity of CO2 in the second container. Repeating the experiments but measuring also the pCO2 in the solvent finds the pCO2 in the solvent is a function of both temperature and the amount of CO2 in the second container, such that mass balance is satisfied. Professor Y concludes that, anthropogenic emissions of CO2 accounts for 0% of the increase in atmospheric CO2, but greater than 100% of the increase in pCO2 in the world’s oceans.

    Various teams rush to replicate Professor Y’s results, and are able to do so with ease.

    The above scenario represents a case where the mass balance argument fails. It is a logically possible world. It is also counterintuitive, but that is not a serious objection to a physical theory since quantum mechanics was accepted. It follows that the mass balance argument by itself cannot demonstrate that the rise in CO2 over the twentieth century is anthropogenic.

    Of course, the above world also represents a world in which Henry’s Law is false. We know the mass balance argument works in this world because we know Henry’s Law is true. As it happens, we also know it because the rise in atmospheric CO2 concentration relative to temperature when there has been no major net source or sink of CO2 has amounted to about 10% of the actual rise over this century. Of course, opponents of the mass balance argument and of the anthropogenic origin of the CO2 can look to other factors that effect pCO2 in the oceans, and hence in the atmosphere above it to provide some other out (salinity and pH, for example), but they will look in vain as the effects of these other factors are well quantified.

  24. Pierre-Normand Houle says:

    ATTP’s OP seems to me to be a fair summary of dikranmarsupial’s argument at Judith Curry’s blog. Willard’s summary, posted above, also seems accurate.

    Let me first make very clear that, in my opinion, the bulk of the evidence that favors a roughly 100% causal attribution to mankind for the recent (since 1750, say) rise in atmospheric CO2 concentration is rock solid.

    My main objection to dikranmarsupial’s interpretation of the mass balance argument is that it rules out the possibility (not just in the actual world, be in counterfactual scenarios) that the anthropogenic causal attribution for the recent rise could be any less than 100% so long as nature as a whole is a net sink.

    (Note: by “causal attribution”, I mean something like “share of the blame”. Those shares add up to 100%. This is unlike the CO2 emissions from the agents responsible for the increase since, as it has already been noted, our cumulative emissions have been roughly 200% of the atmospheric increase.)

    Suppose for instance that (counterfactually) there would have been a huge increase in volcanic emissions over the last few decades, such that the atmospheric CO2 concentration would have reached 410ppm rather than 400ppm in 2015. In that case it seems reasonable to say that the causal attribution would be a little less than 100% anthropogenic. Diklanmarsupial, however, has been very insistent that even in such a case the attribution would still be 100% anthopogenic. His reasoning is that the fact that nature as a whole (including the new massive volcanoes that are temporarily disrupting the slow carbon cycle) *still* is a net sink and so it *still* is merely opposing our emissions, only less strongly.

    This argument seems to me to conflate the claim that nature as a whole isn’t a net source (which is true, and follows from the mass balance argument) with the stronger claim that no part of nature can be ascribed any share of the causal responsibility for the observed increase (which is false, and doesn’t follow from the mass balance argument). That was the root of our disagreement.

  25. Tom,
    Thanks. I thought you might post a comment on this one 🙂

    Pierre,
    But even in your example of a large increase in volcanic activity, if concentrations are still rising more slowly than our emissions, then nature cannot be the source of the rise; if we were to stop emitting concentrations would drop. Of course, if we had never emitted anything and volcanic outgassing had suddenly increased, then it could lead to a rise, but only in the absence of any anthropogenic emissions.

    izen,

    So human emissions could be causing 50% of the observed rise, having triggered an increase in emissions from natural processes twice as large as anthropogenic sources and an increase in sinks 250% greater than human emissions.

    Indeed :-), but like the above, I think it would still be true that nature was not causing the rise at that time; halting anthropogenic emissions would cause concentrations to drop (well, unless the enhanced sink uptake depends on emissions, rather than concentrations. But that seems unlikely).

  26. dikranmarsupial says:

    RickA “Where I am a little confused on attribution is whether the change in Un is anthro or not.”

    Lets use the bank account analogy. Say I have a joint bank account with my wife (which attracts no interest or bank charges and is not accessible by anyone else). My wife decides she would like the balance to stay at £1000 (which is the opening balance). If I then deposit £1000 more a month than I withdraw, then the balance will start to rise. My wife doesn’t want this, so she starts to take out £500 more a month than she puts in. Now is that £500 withdrawn by me or my wife?

    The natural carbon cycle is opposing the anthropogenic rise in atmospheric CO2, saying that the increase in Un is anthropogenic is basically saying that we are adding (say) 5GtC to the atmosphere each year rather than the 10GtC that we actually emit, because we are responsible for the uptake of the other 5GtC. We are not responsible for this uptake, nature is (although it is a response to our cumulative emissions).

  27. Pierre-Normand Houle says:

    ATTP wrote: “But even in your example of a large increase in volcanic activity, if concentrations are still rising more slowly than our emissions, then nature cannot be the source of the rise”

    Is that supposed to contradict anything I said? I didn’t say nature would be “the source of the rise”. This is exactly the conflation that I warned against. I rather said that, under those circumstances, the anthopogenic causal attribution would be lower than 100%. It would be something like 97.5% anthropogenic and 2.5% volcanic (and hence 2.5% natural). The reason for this causal attribution simply is that, were it not for the sudden volcanic increase (and had the anthopogenic emmissions remained exactly the same), the total increase in atmospheric CO2 concentration (from 1975 to 2015) would have ended up being 2.5% smaller.

    It is very strange to reason on the basis of the mass balance argument that if nature as a whole isn’t a net source, then the causal attribution for any possible rise must be 100% anthropogenic, and any independent natural disruption of the carbon cycle ought to be causally attributed 0% of the increase.

  28. dikranmarsupial says:

    Tom, I’m not sure I understand your point, the first issue is the “He reports the pCO2 when it reaches equilibrium” – professor X is not measuring CO2 in an atmosphere that is in equilibrium but professor Y is.

    In the second example, the amount of atmosphere in the flasks that professor Y is measuring is double that in the first, so while the concentration may be the same, the mass of the reservoir (above the water) is higher (rather like there will be more co2 in the Earths atmosphere once the atmosphere has equilibriated with the oceans). Once we re-equilibriate, the Earths atmosphere will contain only slightly more CO2 than it did in pre-industrial times. Now most of the molecules in the atmosphere will have been emitted by the ocean at some point (due to the short residence time), but that increase in equilibrium atmospheric mass is still due to fossil fuel emissions.

  29. Is that supposed to contradict anything I said? I didn’t say nature would be “the source of the rise”. This is exactly the conflation that I warned against.

    Then it sounds like you’re arguing against something that isn’t being said.

    I rather said that, under those circumstances, the anthopogenic causal attribution would be lower than 100%. It would be something like 97.5% anthropogenic and 2.5% volcanic (and hence 2.5% natural).

    Except that if we stopped emitting, concentrations would drop. Hence even if your breakdown is correct, it only applies if we are also emitting. So, in a sense, nature can only be contributing to the rise if we are also emitting and, hence, I would argue that the rise is all anthropogenic.

    It is very strange to reason on the basis of the mass balance argument that if nature as a whole isn’t a net source, then the causal attribution for any possible rise must be 100% anthropogenic, and any independent natural disruption of the carbon cycle ought to be causally attributed 0% of the increase.

    That’s because under any realistic scenario, if we were to suddenly stop emitting, concentrations would drop. Therefore it seems reasonable to argue that the rise is entirely anthropogenic.

  30. Dikran,
    I think Tom is suggesting that there could be a world in which his experiment could be correct, rather than it being a valid experiment in this world.

  31. izen says:

    @-I think it would still be true that nature was not causing the rise at that time; halting anthropogenic emissions would cause concentrations to drop…

    If the question is causation then human emissions are responsible for 200% of the measured atmospheric rise. But if the carbon cycle turnover had been increased by 10%, with a slightly larger increase in sinks over sources, then human emissions would contribute only ~50% of the increase.

    Causation and contribution can have different values if +/- feedbacks are involved.

  32. dikranmarsupial says:

    Pierre-Normand, can you give an example of some everyday situation where X causes the amount of Y in Z to rise whilst taking more Y out of Z than it puts in (where you can substitute suitable nouns for X, Y and Z). The real problem he is the meaning of “cause the increase”, and definitions that would not be acceptable in everyday usage seem to be fine for some when applied to CO2 in the atmosphere. If you can show an everyday usage that supports your point, that would be useful in explaining your position. If you can’t do this, then perhaps that suggests the problem lies with your conception of causality (not such a straightforward concept as it might seem).

  33. dikranmarsupial says:

    ATTP, I don’t see how it is valid in the imaginary world either, but I expect Tom can explain and I’ll do my best to follow.

  34. Pierre-Normand Houle says:

    Dikranmarsupial, your bank analogy is misleading because you wife is a metaphor for nature and the analogy hides the fact that nature has separable causal components. Suppose you daughter Sue hands £10 to your wife for her to deposit in the account on her behalf. Were it not for that, your wife’s deposit would have been £10 pounds smaller. Since you don’t know that, on the basis of the ‘account balance argument’ you are still concluding that your wife is a net financial drag (which is correct) and also inferring that you are 100% responsible for the bank account increase (which is incorrect). That’s because Sue still is causally responsible for part of the increase (namely £10). You aren’t thus yourself responsible for all of it. Sue shares a small part of the credit with you.

    This argument is further elaborated here:

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760367

  35. Pierre-Normand Houle says:

    dikranmarsupial asked: Pierre-Normand, can you give an example of some everyday situation where X causes the amount of Y in Z to rise whilst taking more Y out of Z than it puts in.

    No, it is impossible. But it would be a fallacy to infer from the fact that X is taking more Y out of Z than it puts in that, therefore, no constitutive part of X can’t contribute to cause the amount in Z to rise.

    Counterexample in an everyday situation: “Sue”. (See my response to your bank analogy).

  36. dikranmarsupial says:

    Pierre-Normand in the analogy my wife represents the natural carbon cycle, so if you are going to add “sue” then Sue must either be extra-terresrial or supernatural, as after you exclude anthropogenic influences (me) and natural influences (my wife), that is pretty much all that is left. So which is it?

    If you want to represent the different components of the natural carbon cycle, you could do that by accounting for my wifes spending and earning in different categories (e.g. salary, dividends from shares, spending on food, mortgage payments and hats). If she had an increase in salary (representing volcanoes) but still spent more than she saved, she would still be opposing the rise in the balance and I would still be the cause of the increase in the balance.

    As to the challenge being impossible, yes, that is the point!! It shows that you are using a definition of causality that would not be acceptable in any other setting, so you need to justify why it is acceptable when applied to CO2 in the atmosphere.

  37. Pierre-Normand Houle says:

    PNH: “I rather said that, under those circumstances, the anthopogenic causal attribution would be lower than 100%. It would be something like 97.5% anthropogenic and 2.5% volcanic (and hence 2.5% natural).”

    ATTP: “Except that if we stopped emitting, concentrations would drop. Hence even if your breakdown is correct, it only applies if we are also emitting. So, in a sense, nature can only be contributing to the rise if we are also emitting and, hence, I would argue that the rise is all anthropogenic.”

    The truth of this counterfactual conditional statement supports the claim that we are responsible for the fact that the atmospheric CO2 concentration is now rising rather than dropping. That’s because, in that scenario, humans contribute much more than volcanoes to the increase. But that doesn’t really speak the issue of the quantification of the shares of the responsibility for the accumulated CO2 amount owed to various contributors.

    To see the defect in your reasoning consider that India could make the exact same argument, pointing out that if it (India) were to stop completely all its emissions, the atmospheric CO2 concentration would still be rising, whereas if the rest of the world would stop, then the atmospheric concentration would begin to fall. Hence they could claim that the rise is 100% rest-of-the-wold-o-genic and 0% Indo-genic.

  38. dikranmarsupial says:

    Pierre-Normand “Counterexample in an everyday situation: “Sue”. (See my response to your bank analogy).”

    Nope. X = Sue; Y = money; Z = Bank account, this fails because Sue is putting more money into the bank account than she is putting in, not less, so it isn’t a counterexample.

  39. Pierre-Normand Houle says:

    dikranmarsupial wrote: “Pierre-Normand in the analogy my wife represents the natural carbon cycle, so if you are going to add “sue” then Sue must either be extra-terresrial or supernatural”

    No. Sue represents a component of nature (Your wife makes a deposit on her behalf). She is an independent component of the carbon cycle — a massive super-volcano, say. We also suppose that Sue isn’t just a regular component of the ordinarily balanced slow carbon cycle (which might be balanced over the relevant time frame of attribution) but rather a temporary source of imbalance. It has a temporary disrupting effect on atmospheric CO2 concentration just in the same sense that humans have such an effect.

  40. dikranmarsupial says:

    Pierre-Normand, Sue is not a component part of something, she is a separate entity, as I keep saying you can’t treat a component part separately, without considering the fact that that makes the other part an even bigger sink – it is a zero-sum game you are playing.

    Try answering my revised analogy, where my wifes different sources of income and expenditure represent different sources and sinks in the natural carbon cycle. If my wifes salary increases, but she still spends more than she saves, is she a cause of the increase in the balance, yes or no?

  41. Pierre-Normand Houle says:

    dikranmarsupial: “Nope. X = Sue; Y = money; Z = Bank account, this fails because Sue is putting more money into the bank account than she is putting in, not less, so it isn’t a counterexample.”

    You are misconstruing my response. I acknowledged explicitly that it is impossible to meet your challenge. But I pointed out that what it purports to show, while true, doesn’t entail that no *part* of X can causally contribute to the increase of Y in Z. Now you are just refusing to countenance my counterexample to such an invalid entailment.

    Suppose this would occur in real life. After you close the account and bring the cash home, are you going to deny Sue her fair share (however small) just because it was deposited in the account by the same person (your wife = nature) who made much larger withdrawals (on behalf of the oceans)? This is all your argument boils down to. You are denying that a super-volcano could be causally responsible for a small percentage of atmospheric CO2 increase (visible as a discernible bump in the Mauna Loa record, say) just because the volcano is part of nature and nature as a whole is a net sink.

  42. dikranmarsupial says:

    Pierre-Normand, O.K., I see your point, but then again you have missed mine. It isn’t a matter of logic, it is a matter of the meaning of “cause”. If you are using a definition of “cause the rise” that appears to be unique to the carbon cycle, then that suggests that there is a problem with your position and you are refusing to acknowledge that.

    So, please could you address the question I asked. If my wife had an increase in salary (representing increased volcanic activity) but still spent more than she saved, would she be causing the balance to rise, or be opposing the increase in the balance?

  43. Pierre-Normand Houle says:

    dikranmarupial: “Try answering my revised analogy, where my wifes different sources of income and expenditure represent different sources and sinks in the natural carbon cycle. If my wifes salary increases, but she still spends more than she saves, is she a cause of the increase in the balance, yes or no?”

    No she isn’t. Why is it difficult for you to conceive of the possibility that nature — or the carbon cycles’ reservoirs and processes — as a whole can have causally separable components such that some one of those components (e.g. a super-volcano) can have a real quantifiable effect while the whole (including the oceans) have an opposite and larger effect? This is like arguing that Memphis couldn’t possibly contribute to increasing the U.S. crime rate if Tennessee is lowering it.

  44. whereas if the rest of the world would stop, then the atmospheric concentration would begin to fall.

    Why? This isn’t obvious, and is essentially the crucial point. Of course, we could choose a country with such small emissions that it would be true, but that would be rather pedantic.

  45. I see your point, but then again you have missed mine.

    I do think this is part of the issue, in that we’re talking past each other. It seems clear that the fact that it is rising is entirely anthropogenic (i.e., there is no realistic scenario under which we could halt all emissions and it would continue to rise). The rate of rise, however, does depend on the natural sources and sinks, so they are contributing to how fast it is rising. I would argue that that still means that the rise is entirely anthropogenic, but it’s clear that the precise rise does depend on the natural contributions. However, that would imply that any attempt at attribution is simply saying something like “it is x% higher/lower than it would be if this natural thing had not happened”.

  46. dikranmarsupial says:

    Pierre-Normand “No she isn’t”

    Exactly, in this case a component source of the natural carbon cycle (e.g. volcanic activity, represented by my wife’s salary) has increased, but we agree that nature (my wife) is not a cause of the rise in CO2 (the bank balance).

  47. Pierre-Normand Houle says:

    dikranmarsupial,

    My use of the concept of a causal contribution is straightforward. You are the one arguing that the mass balance argument all by itself is sufficient to prove that a rise in atmospheric CO2 concentration is 100% anthropogenic. This is a causal attribution statement. “Anthopogenic” means “caused by mankind”. Suppose China is responsible for 10% of the cumulative emissions (I am making this figure up). Would you not say that China is causally responsible for some similar share of the atmospheric increase? China’s contribution is causal just because had China not released any emissions, then the atmospheric increase would be (very roughly(*)) proportionately lower. This is how I am using the words “cause” and “causally”. However, I am reserving it for real “events”, as is done in ordinary usage. Hence normal components (sources and sinks) of the normal carbon cycle don’t count as causes if they are operating at normal rates and there is no unusual natural disruption of the cycle’s steady state.

    (*) Percentages of causal attribution for an effect can be defined in various ways when the causes aren’t additive, as is the case for the causal contributions of various non-condensible GHGs in the atmosphere. Adding a gas to the lot doesn’t have the same effect that it would have in isolaton).

  48. dikranmarsupial says:

    ATTP indeed, but I would say that “opposing the increase less” is not the same as “causing the increase”. The natural carbon cycle has opposed the rise more in some years than in others, but it has always been acting to counteract the rise over the course of the Mauna Loa record.

    Now I have never said that some component parts of the natural carbon cycle act in a way that tends to increase the level of atmospheric CO2, however that does not mean that nature is a cause of the rise, at least according to normal usage of “cause” (as demonstrated by the X, Y, Z) challenge.

    Now if you want to look at individual sources and sinks, rather than an anthropogenic/natural attribution, then the way to do it is to look at the percentage of the rise caused by each source and each sink. So anthropogenic sources is 200%, oceans are -50%, terrestrial biota -50% volcanos are 0.4% (or whatever), such that everything adds up to 100%.

    So you could say that volcanoes are responsible for 0.4% of the rise, provided you were then happy to say that mankind was responsible for 200% and nature in general a bit over 100%. It is still incorrect to say the rise is natural, as the natural contribution is negative.

  49. dikranmarsupial says:

    Pierre-Normand “My use of the concept of a causal contribution is straightforward. ”

    Yes, but it appears to be unique to discussion of the carbon cycle, as your inability to provide a counter example to the X,Y,Z example shows.

  50. So you could say that volcanoes are responsible for 0.4% of the rise, provided you were then happy to say that mankind was responsible for 200% and nature in general a bit over –100%. It is still incorrect to say the rise is natural, as the natural contribution is negative.

    Yes, this seems to be a key point. If you want to conclude that some parts of nature have contributed to the rise, then you have to also allow for other components to contribute more than 100% (either positive or negative).

  51. Pierre-Normand Houle says:

    DM wrote: Exactly, in this case a component source of the natural carbon cycle (e.g. volcanic activity, represented by my wife’s salary) has increased, but we agree that nature (my wife) is not a cause of the rise in CO2 (the bank balance).

    Sure. What we are disagreed about is the detailed attribution of (part of) the total effect from your wife’s withdrawals from the bank account. If your wife represents nature, then you must allow that she has components. You could say that 100% of your wife’s effect is to lower the account balance. But then, your wife’s effect minus Sue’s effect (= the ocean’s response) may be having 105% of your wife’s total effect, while Sue (super-volcano) has -5% of this effect.

    In the causal attribution for the atmospheric CO2 increase, for policy analysis purpose, we are looking at the shares of the several contributors (e.g. countries, industry sectors, personal footprints, or whatever useful division) to the disruption. We are not attributing any responsibility share to the sink response (oceans and biosphere). Hence, your wife’s own withdrawals, apart from Sue’s contribution, would drop out from the equation for purpose of percentage attributions of the total effect. But this isn’t mandatory. Being fussy, we could calculate that your wife is causally responsible for minus 500% of the final account balance, say, and the separable causal attributions proportioned to the net deposits (from yourself, Sue, and whoever else contributed positively) would then add up 600% rather than 100% of the final account balance. But they would be relatively proportioned just the same (i.e. all multiplied by 6, in this case).

  52. dikranmarsupial says:

    Indeed, the point is that the fact that volcanoes contribute 0.4% of the rise doesn’t mean that the rise is natural, because that would be ignoring the -100% that is the influence of the rest of the natural carbon cycle.

    I suspect that if we were doing meaningfull amounts of CCS then everybody would make sure that was taken fully into account in assessing whether the rise was anthropogenic! ;o)

  53. dikranmarsupial says:

    Pierre-Normand wrote “Sure”

    O.K., so you agree then that the mass balance argument is sufficient to establish that the rise is anthropogenic and not natural, although the natural carbon cycle does include sources that tend to increase the level of atmospheric CO2 as well as sinks that tend to oppose it?

  54. dikranmarsupial says:

    BTW, as I pointed out “Sue” is unnecesarily obfuscating things as “sue” and “my wife” are separate entities in the analogy, but they are component parts of a single entity in the reality the analogy is intended to reflect (i.e. the natural carbon cycle), which I think is causing a lot of the confusion. There is no need for this, it is much clearer to use the different streams of income and expenditure to represent these different components in a more accurate and coherent manner. Please drop “Sue” from further analogies, she really isn’t helping.

  55. dikranmarsupial says:

    ATTP wrote “Yes, this seems to be a key point. If you want to conclude that some parts of nature have contributed to the rise, then you have to also allow for other components to contribute more than 100% (either positive or negative).”

    And make sure to mention that while some parts of parts of nature have made a small contribution to the rise, the other parts have made a much larger negative contribution opposing the rise. Looking at only the sources and ignoring the sinks is a classic source of climate myths, e.g. “anthropogenic emissions are only a small fraction of natural emissions” completely true, but also completely misleading!

  56. Pierre-Normand Houle says:

    ATTP wrote: “Why? This isn’t obvious, and is essentially the crucial point. Of course, we could choose a country with such small emissions that it would be true, but that would be rather pedantic.”

    The airborne fraction is currently close to 50%. This means that our emissions are about twice the rate of atmospheric increase. This means that the rate of absorption by natural sinks is about equal to the rate of atmospheric increase. Since the rate of absorption is governed by atmospheric CO2 concentration, and this would not immediately change if we would suddenly stop all emissions, it follows that, initially at least, the atmospheric CO2 concentration would begin to drop. If we would cut emissions by half, it would stabilize (more of less). So, I merely assumed that India’s share of emissions is much less than half the total anthropogenic emissions.

    In any case, you didn’t address my point. Why is it that a super-volcano can’t be causally credited with a positive share of the increase, however small while a small country that produces similar emissions would be so credited? You argument for disqualifying the volcano was because if all of the other sources (total anthopogenic, in this case) were to stop, then the atmospheric concentration wouldn’t rise anymore. But this argument would disqualify most countries on Earth from being attributed any positive share of the causal contribution to the increase, if it were sensible.

  57. Pierre-Normand Houle says:

    dikranmarsupial wrote: “BTW, as I pointed out “Sue” is unnecesarily obfuscating things as “sue” and “my wife” are separate entities in the analogy, but they are component parts of a single entity in the reality the analogy is intended to reflect (i.e. the natural carbon cycle), which I think is causing a lot of the confusion.”

    If you don’t like me making references to separable components (Sue) of the total carbon cycle (your wife), and hence would rather not talk about Sue at all, then I indeed can’t make my argument. Sue merely represents a natural disruptive event in the carbon cycle (a big volcano), just like she represents a disruptive event in your wife’s banking habits (the whole carbon-cycle minus human emissions). You think this is obfuscation but it is just an attempt to call your attention on a blind spot where you seem unable dissociate causal attributions to nature as a whole (including passive sinks that respond indiscriminately to human and natural events/forcings) from causal attributions to specific natural events. My so-called “obfuscation” just is my resolving of your conflation.

    You yourself introduces the Smith/Jones examples (at Judith Curry’s), where you said the purpose of using families was precisely in order to address my insistence that the carbon cycle separable causal components. There also, you failed to see that for the whole Jones family to have a negative causal contribution doesn’t preclude one sigle Jones family member from having a real positive causal contribution. So you can refer to my comment on this example of yours.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760367

  58. Since the rate of absorption is governed by atmospheric CO2 concentration, and this would not immediately change if we would suddenly stop all emissions, it follows that, initially at least, the atmospheric CO2 concentration would begin to drop.

    I’m not convinced that this is correct. You can play around with the Geocarb model. Set the transition CO2 spike to about 340GtC, that will set the initial concentrations at about 400ppm. Then on the right hand side, you can vary the simulation degassing rate. To get concentrations to start dropping, you need the degassing rate to be about 10% of our current emissions.

    In any case, you didn’t address my point. Why is it that a super-volcano can’t be causally credited with a positive share of the increase, however small while a small country that produces similar emissions would be so credited?

    I think I have really. I’m with Dikran here. If you want to start attributing some to small parts of the system, then you also need to allow for other contributions to be greater than 100%. If that’s what you’re arguing for, then we probably agree. I think we’re essentially talking past each other now, to be quite honest.

  59. dikranmarsupial says:

    Pierre-Normand “If you don’t like me making references to separable components (Sue) of the total carbon cycle (your wife), and hence would rather not talk about Sue at all, then I indeed can’t make my argument”

    Of course you can, you can use the different streams of income and expenditure of my wife to represent the different sources and sinks comprising the natural carbon cycle, just as I did. However, as we have seen, that leads to you agreeing that the rise in atmospheric CO2 (bank balance) is not caused by nature (my wife) even though some natural sources increase their emissions (my wife’s rise in salary).

  60. dikranmarsupial says:

    Pierre-Nomarnd wrote ” There also, you failed to see that for the whole Jones family to have a negative causal contribution doesn’t preclude one sigle Jones family member from having a real positive causal contribution.”

    You obviously did not read my initial statement of the analogy properly as the fact that an individual member of the Jones family was a contributor was explicitly stated.

    Consider a bank account shared between two families, the Smiths and the Jones. If the Smiths notice that their net transactions results in £100 per month more being put into the account than is taken out, but the balance rises at only $50 per month then they know that the Jones take $50 more out of the account than they put in. It doesn’t matter that Pa Jones puts in $1000 more in per month than he takes out, the Jones are not causing the balance to rise, the Smiths are. Attributing the rise in CO2 to anthropogenic and natural causes is like attributing the rise in the balance to the Smiths and the Jones’. If Pa Jones is a big net contributor, then that means some other member of the Jones family must be big net spender. Likewise volcanoes may be a net carbon source, but that just means that other elements of the carbon cycle are bigger net sinks, and the anthropogenic/natural attribution needs to consider all natural sinks and net sources.

  61. Pierre-Normand Houle says:

    dikranmarsupial: “And make sure to mention that while some parts of parts of nature have made a small contribution to the rise, the other parts have made a much larger negative contribution opposing the rise. Looking at only the sources and ignoring the sinks is a classic source of climate myths.”

    You often make this charge, that I am ignoring some contributions from nature. But you never point out any relevant contribution that I ignored in any of the specific examples that we discussed. What you rather do is to lump any natural event that I mention together with the rest of nature (including the passive sinks), point out that this is a net sink, which I acknowledge, and claim that I ignored it, which I didn’t. And you then infer that nature doesn’t have any effect in the specific example. This is begging all the questions. You can’t show that something doesn’t have an effect just because, combined with other things, the effects is reversed. That would only be valid if the other cancelling (or overwhelming) effects were active responses to the alleged effect such that the initial disruptive event doesn’t lead to an outcome that is different than the normal outcome (in the absence of the disruption).

    Likewise for the super-volcano. Sure, the natural sinks actively oppose its effect. But had the volcano not occurred, the atmospheric concentration would have been lower. This is enough to credit the volcano with the difference.

  62. Likewise for the super-volcano. Sure, the natural sinks actively oppose its effect. But had the volcano not occurred, the atmospheric concentration would have been lower. This is enough to credit the volcano with the difference.

    Yes, this is true. You therefore want to argue that this change is attributable to the volcano. I guess that is indeed true. However, the other way to look at this is that the volcano has reduced the net uptake by the natural sinks, increasing the airborne fraction. Okay, a volcano might be a truly independent natural release of CO2. Permafrost release, on the other hand, would not. We can probably spend all day arguing about this. As far as I can see, we largely agree about the process, we’re simply disagreeing about some fine details.

  63. Pierre-Normand Houle says:

    ATTP: “I’m with Dikran here. If you want to start attributing some to small parts of the system, then you also need to allow for other contributions to be greater than 100%.”

    Even if true, this ought only to trouble Judith Curry. Aren’t we possibly responsible for more than 100% of the observed warming? If there would have occurred natural events that increased the effectiveness of the natural CO2 sinks in the last couple centuries, this would mean that, were it not for our emissions, then the atmospheric CO2 concentration would have dropped. If we were to discover that this indeed had been the case, then the anthropogenic causal attribution to the observed increase would be larger than 100%. Where is the problem? And likewise, if there had occurred natural events that reduced the effectiveness of the natural sinks… you see what I mean.

    For instance, as you note in the OP, if the recent warming hasn’t been anthropogenic, then nature would have caused some of the increase without our help. That is not the case, but the fact that the warming (and consequent reduction in effectiveness of the oceanic CO2 sink) is anthropogenic can hardly be inferred from the mass balance argument alone.

  64. “As far as I can see, we largely agree about the process, we’re simply disagreeing about some fine details.”

    ATTP, it’s not some fine details. You started this by saying “that a particularly elegant way to illustrate that the rise is anthropogenic is to simply consider mass balance”. The mas balance doesn’t say anything about the causes of the rise. It’s a non sequitur fallacy – the causality of the change does not follow from the mass balance.

  65. dikranmarsupial says:

    ATTP indeed, nature opposing the rise less does not mean that it is a cause of the rise. It is largely the use of language that is the issue here.

  66. The mas balance doesn’t say anything about the causes of the rise. It’s a non sequitur fallacy – the causality of the change does not follow from the mass balance.

    I think it essentially does. The anthropogenic contribution is the only contribution for which the net emissions exceeds the rise in atmospheric CO2. That some other part might have some small net positive contribution does not change this. Furthermore, there isn’t – as far as we know – some other part that has some net positive contribution.

  67. dikranmarsupial says:

    “Likewise for the super-volcano. Sure, the natural sinks actively oppose its effect. But had the volcano not occurred, the atmospheric concentration would have been lower. This is enough to credit the volcano with the difference.”

    The volcano yes, nature no. I have been consistently making this distinction throughout (e.g. “Pa Jones” verses “the Jones” as a family). The fact that there are natural sources/contributors to the rise does not imply that the rise in CO2 is natural. This is because whether the rise is natural, anthropogenic or a bit of both depends on whether nature is a net contributor, as demonstrated by the X/Y/Z challenge.

  68. Pierre-Normand Houle says:

    dikranmarsupial: “You obviously did not read my initial statement of the analogy properly as the fact that an individual member of the Jones family was a contributor was explicitly stated.”

    I just said “*causal* contributor”. Your argument precisely is designed to disqualify her (Sue Jones) from being a *causal* contributor, in spite of her being a contributor [i]simpliciter[/i] (e.g. an ordinary CO2 source part of the normal carbon cycle). And your only reason for disqualifying her as a causal contributor to the account balance increase (and hence for attributing 100% of the credit to the Smith family) is that the Jones family as a whole made net withdrawals. You interpret this as analogous to natural sinks overwhelming the contribution of a super-volcano. Hence, in this analogy, the other members of the Jones family are analogous to the natural CO2 sinks (oceans + biosphere). But the only sensible reason for disqualifying Sue Jones as a causal contributor, and not similarly disqualify other individual members of the Smith family, would be if the other Jones’s (the sinks) were responding dynamically and selectively to Sue’s contributions in such a way that her actively increasing her contributions wouldn’t change anything to the bank balance. But then the analogy would be flawed since oceans don’t respond selectively to volcanic CO2 in such a way that the occurrence or non-occurrence of a super-volcano would not make any difference to atmospheric CO2 concentrations.

  69. dikranmarsupial says:

    Pierre-Normand. Rubbish, Pa Jones is a “causal contributor” in my original analogy just the same as “sue” is in yours. There is no difference at all between “Pa Jones” in my analogy and “Sue Jones” in yours. The difference lies in that in my analogy “Pa Jones” is a component part of “The Jones”, where as in yours “Sue” is not a component part of “my wife”, but a separate entity, which leads to the unnecessary confusion that I have pointed out.

  70. dikranmarsupial says:

    I agree with ATTP, that we are talking past eachother, but I think that is at least in part due to you not reading the original analogy properly and seeing that the Jones’ does have components that (causally) contribute to the rise, even though it is not correct to say that the rise is caused by the Jones family.

  71. Pierre-Normand Houle says:

    ATTP: “I’m not convinced that this is correct. You can play around with the Geocarb model. Set the transition CO2 spike to about 340GtC, that will set the initial concentrations at about 400ppm. Then on the right hand side, you can vary the simulation degassing rate. To get concentrations to start dropping, you need the degassing rate to be about 10% of our current emissions.”

    OK, thanks for that. This is a side issue but interesting in its own right. But it puzzles me. That would seem to imply, if true, that were we to immediately cease our emissions, the natural sink rate would rapidly drop to 20% the current rate. This can’t be a result from a change in (well mixed) atmospheric partial CO2 pressure, since this would not initially change much. Would it have something to do with the change in flux at the ocean surface? I guess that must be what I overlooked. The net flux would drop from being equal to our emission rate to being close to zero.

  72. Pierre-Normand Houle says:

    “The net flux would drop from being equal to our emission rate to being close to zero.”
    …10% rather.

  73. dikranmarsupial says:

    Lets try this: The Smiths and the Jones’ have a savings account. The Smiths pay in £1000 per week and take out nothing. Pa Jones saves £1000 per month and takes out nothing (causally contributing to the rise in the balance) however Ma Jones and their children between them save nothing and take out £1500 per month. Therefore the balance rises by £500 per month, and after a year the final balance is £6,000.

    Now how much of the rise in the balance (in £) was caused by the Jones family?

  74. Pierre,
    I think it’s a rather tricky issue and I’m not sure I quite have it either. There’s also this which suggests that if we were to essentially half our emissions instantly and then more slowy reduce them to zero (over many decades) it would fix atmospheric CO2. I think that also suggests that simpy halving our emissions is insufficient. I think one way to consider this as some kind of exponential decay of a series of pulses, one for each year. Our emissions from a long time ago have almost all decayed. More recent ones have decayed less. etc.

  75. Pierre-Normand Houle says:

    dikranmarsupial: “I agree with ATTP, that we are talking past eachother, but I think that is at least in part due to you not reading the original analogy properly and seeing that the Jones’ does have components that (causally) contribute to the rise, even though it is not correct to say that the rise is caused by the Jones family.”

    This has been my whole point since the very beginning of the conversation at Judith Curry’s place. I have been hammering the point that one can’t infer from the fact that nature as a whole isn’t a net contributor to the rise (the legitimate conclusion of the mass balance argument) that, therefore, no separable natural component is a causal contributor to the rise. Hence the total cause of the rise can be apportioned between the anthropogenic components and the (very likely smaller) natural components. The mass balance argument, in itself, doesn’t show that there are no natural components to the cause of the increase. When supplemented with other pieces of evidence, such as analysis of the specific carbon cycle components, or the very strong correlation between atmospheric concentration and cumulative anthropogenic emissions, then it becomes conclusive.

    In the Smith/Jones case, the bank balance increase has a discernible Sue-genic component, and isn’t therefore 100% Smith-o-genic.

  76. dikranmarsupial says:

    “This has been my whole point since the very beginning of the conversation at Judith Curry’s place.”

    In that case, perhaps you should ask yourself why you didn’t stop hammering when I gave the Smith/Jones analogy, where that was made explicit?

    “In the Smith/Jones case, the bank balance increase has a discernible Sue-genic component, and isn’t therefore 100% Smith-o-genic.”

    O.K. I am interested the in your answer to my most recent post.

  77. dikranmarsupial says:

    ““In the Smith/Jones case, the bank balance increase has a discernible Sue-genic component, and isn’t therefore 100% Smith-o-genic.”

    Are you arguing that it is more than 100% smith-o-genic or less?

  78. Pierre-Normand Houle says:

    diklanmarsupial, the point of the difference between “causal contribution” (disruptive sources) and mere non-causal contribution (regular sources) is that causal attribution is aimed at explaining why the atmospheric CO2 concentration, which has been stable around 280-300ppm for millennia, suddenly began increasing. There was a balance between sinks and sources and this balance has been broken. Something counts as a cause if it contributes to explain some fraction of the rise in atmospheric CO2. The normal (regular) sources and sinks don’t explain this because they are in dynamic equilibrium. What is sought is the source of the rupture of this equilibrium. Therefore, something (or some event) is credited as a cause if its new action (or abnormal occurrence) makes a positive contribution to the increase.

    The analogy would be better if the Jones’s and Smiths had been making regular withdrawals and deposits for a long time while the account balance remained stable, and then the account balance began increasing. We can then look at the ‘sinks’ and ‘sources’ that actively changed (the Smiths and Sue,merely sources in this case), and those that passively responded (All of the Jones except Sue). If we can investigate and discover the underlying dynamics, then we can begin to make causal attributions. The individual elements will be credited as independent causal contributors for the increase if they autonomously (that is not as mere feedbacks) changed their behaviors, and the outcome would have been different if they hadn’t.

    It is on the basis of this understanding that we can establish that Sue, and the Smiths, rather than the Smiths alone, share among them the credit for the rise.

  79. Pierre-Normand Houle says:

    dikranmarsupial “Are you arguing that it is more than 100% smith-o-genic or less?”

    Less. Lets add up the total net deposits from each of the Smith family members (the emissions from the different Earth nations, say), and the total net deposits from Sue (the total CO2 releases from the super-volcano) and divide each by the total to ascribe shares of the causal attribution for the bank balance increase. The anthropogenic attribution then just is the sum for the attributions for all of the Smiths. Sue’s attribution is the natural attribution. All of those sum up to 100%. This causal attribution makes sense if the different contributors are acting independently, which, in the case of Sue (the volcano) we can safely assume.

  80. Pierre-Normand Houle says:

    dikranmarsupial: “In that case, perhaps you should ask yourself why you didn’t stop hammering when I gave the Smith/Jones analogy, where that was made explicit?”

    Because my response to that post was held in moderation for two days, and I always had this argument of yours in mind. If my points don’t get across, I keep hammering, and so are you doing. Nothing wrong with that, provided civility and patience remain valued. At least, over here, this isn’t off topic.

  81. dikranmarsupial says:

    So where do the natural sinks fit into this analysis (i.e. the other Jones family members)?

    You Say “Sue’s attribution is the natural attribution”, but the net deposits for Sue represent “the total CO2 releases from the super-volcano) which is not the totality of the natural influence. This is the “ignoring the sinks”. It is not clear why you say “net deposits”, volcanoes are pure sources of CO2 into the atmosphere.

    Note “Sue” doesn’t actually appear in the smith-v-jones bank analogy, perhaps you meant Pa Jones?

    In the analogy the Smith’s net contribution to the rise is greater than the amount of the rise, and yet you claim that the Smiths are responsible for less than 100% of the rise. That doesn’t sound right to me.

  82. dikranmarsupial says:

    Pierre-Normand I think part of the problem here is that there are too many (variations) of analogies here. I susggest we go back to the simplest that captures the most basic elements of the problem and work with that (without modification) until we agree what it means and then go onto the next step. I propose we start with my earlier question:

    The Smiths and the Jones’ have a savings account. The Smiths pay in £1000 per week and take out nothing. Pa Jones saves £1000 per month and takes out nothing (causally contributing to the rise in the balance) however Ma Jones and their children between them save nothing and take out £1500 per month. Therefore the balance rises by £500 per month, and after a year the final balance is £6,000.

    Now how much of the rise in the balance (in £) was caused by the Jones family?

  83. Pierre-Normand Houle says:

    PNH: “All of those sum up to 100%. This causal attribution makes sense if the different contributors are acting independently, which, in the case of Sue (the volcano) we can safely assume.”

    Let me add that if, as a result of this method of attribution, Canada and Japan both get attributions of 10%, say, that doesn’t mean that if one of then hadn’t emitted anything the rise in atmospheric concentration would have been 10% smaller. It only means that they contributed equally. Also, this method doesn’t guarantee either that if China gets an attribution of 20%, say, then the separable impact (comparison with the case with zero Chinese emissions) of China would be twice the separable impact from Canada. In spite of those difficulties, the attribution roughly represent the various causal contributions of the various causal agents since they are approximately proportional to their respective impacts.

    (“Specific impact of an agent” =def the difference made to the final atmospheric CO2 concentration produced by the actual emissions from all the causal agents compared with a counterfactual scenario with zero emissions from this agent).

  84. Maybe I’m missing something here, but isn’t the argument becoming something like this.

    Bank account increases at $500 per month.

    Every month:

    Person A: $1000 in, $0 out

    Person B: $500 in, $800 out

    Person C: $500 in, $800 out

    Person D: $200 in, $100 out

    Dikran and I would say that the rise is entirely due to person A since their contribution exceeds the rise. Pierre would say it’s mostly A but partly D, because D’s contribution is net positive.

    It’s clear that D’s contribution contributes to the rate of increase, but without A it would not be increasing. (hopefully I haven’t blundered somewhere here).

  85. dikranmarsupial says:

    ATTP I think it is important to mention that B, C and D are integral of a consortium. I A, B, C and D were independent entities, then I would be O.K. with the idea that the rise is partly due to A and to a lesser extent to D, but without the consortium part, it no longer maps onto the anthropogenic-v-natural attribution question.

  86. dikranmarsupial says:

    If they were treated as separate individuals, it would be fine to say that A was responsible for 200% of the rise, B -60%, C -60% and D +20% (summing hopefully to 100%). If you were to divide up the money fairly at the end you would give the lions share to A and some to D and none to B or C.

    If it is A and the cartel, then clearly it is A is responsible for 200% and the cartel -100%. If you were to divide the balance up at the end fairly, it would all go to A and none to the cartel. This is because even though D contributed to the rise, the cartel did not cause the rise, it opposed it.

  87. I haven’t read everything in the thread since yesterday, as I have a (man’s) flu and will take a timeout today. I read Tom’s comment, Edim’s and I think I can refute the claim that it would be impossible to see causality Pierre-Normand’s way.

    ***

    Tom, I’m not sure I understand how your thought experiment refutes the argument laid down with numbering system above, which only rewords everything Dikran said in a previous thread at Judy’s:

    https://andthentheresphysics.wordpress.com/2016/01/26/mass-balance/#comment-71562

    At worst Dikran would need to add Henry’s Law to (5), but I think your counterexample runs contrary to (0).

    ***

    Edim, the kind of causality that follows from the mass balance argument is what Lackoff calls systemic causation:

    http://judithcurry.com/2012/11/05/systemic-thinking-on-causation/

    While it would be indeed possible to imagine a scenario where some parts of the nature may have contributed to the rise, the balance argument tells us where to find the main culprit. It’s the same as in Clue: you have two rooms, and while some evidence points to the Nature room, you know that the principal suspect is in the Men’s room.

    ***

    There’s a very simple way to see Pierre-Normand’s argument. You got two portfolio with stocks in them. Your portfolio A is in the red, while the portfolio B is profitable. It’s quite possible that there are some stocks in A with a sizeable profit, just like it’s quite possible to find stock in B that you should have sold way before they drop below the buying price.

    The last possibility doesn’t correspond to what we know, because of (2) above, i.e. anthropogenic uptake is essentially zero. A human sink is not impossible, however. I believe it’s the Gnome Underpants plan that Senior’s dogwhistling.

    In any case, it’s quite clear where the main source of profits comes from: portfolio B. Without B, we’d be either in the red or underperforming.

    ***

    Have fun for the remaining of this exchange.

    W

  88. Dikran,

    I think it is important to mention that B, C and D are integral of a consortium.

    Agreed. I missed that bit of the analogy.

  89. RickA says:

    ATTP:

    I was thinking about this issue more last night.

    You had said earlier in our exchange “Are you suggesting that we take credit for the fact that the natural sinks take up some of our emissions? ”

    The nature/anthropogenic attribution is all a matter of perspective and it can be looked at both ways.

    You had looked at it one way and I showed you that it is possible to turn it around and look at it from another perspective which is perfectly valid (in my opinion).

    If you follow this reasoning (your perspective) – one could say that the warming of the Earth is a natural response of the atmosphere and the ocean to some of our emissions. So the warming since 1950 would be natural.

    Or you could say that the sea level rise is a natural response of the glaciers melting and the ocean thermally expanding in response to some of our emissions. So the sea level rise would be natural.

    But of course, the consensus blames 100% of the warming since 1950 on humans and the increased rise in sea level on humans. We get the blame.

    I think there is a cognitive bias at work here.

    I have read that humans feel remembered pain 10 times more intensely than they feel remembered pleasure.

    This makes humans risk averse – which is an evolutionary response to the fact that bad things can kill, while good things can be taken or not (usually without harm).

    So humans tend to pay more attention to BAD things than GOOD things.

    Warming is BAD.

    Rising sea level is BAD.

    So we pay attention to those.

    Increased natural sink uptake is GOOD, so it is minimized or ignored.

    That is why we are giving all the credit for the increase in Un to NATURE, rather than providing a term for Ua and giving some of the credit to humans.

    To give some more examples – earthquakes induced by fracking.

    We could call these earthquakes a natural response to the water we put down fracking wells.

    But I think we blame this on humans (so they are considered anthro).

    That is because these earthquakes are BAD.

    Warming is BAD – but we have also seen our crops produce a 40% higher yield per acre. This is GOOD. It is because of the CO2 fertilization effect and also because plants use water more efficiently at higher CO2 levels – so the same water goes further. This good effect is ignored or minimized.

    We should be looking at the NET effects of human actions.

    In order to do that we have to measure the BAD and the GOOD, and then net them.

    In my opinion, we are not paying enough attention to the GOOD things, probably because of our cognitive bias – and our netting is therefore a little faulty.

    We do need a term for Ua in the the mass balance exercise.

    I think humans should get the credit for the increased natural uptake of natural sinks, because it is caused by our increased emissions.

    Thoughts?

  90. Pierre-Normand Houle says:

    dikranmarupial wrote: “The Smiths and the Jones’ have a savings account. The Smiths pay in £1000 per week(sic) [month] and take out nothing. Pa Jones saves £1000 per month and takes out nothing (causally contributing to the rise in the balance) however Ma Jones and their children between them save nothing and take out £1500 per month. Therefore the balance rises by £500 per month, and after a year the final balance is £6,000.

    Now how much of the rise in the balance (in £) was caused by the Jones family?”

    The question is ambiguous and invites an equivocation. But the equivocation can easily be avoided through explaining the additional assumptions required to motivate the two possible (and equally reasonable) answers.

    For simplicity, let us treat Ma Jones and her children as a single entity.

    The effect to be ascribed to various causal agent is the final account balance of £6,000

    In one year, Ma’s impact on the account balance is (-)£18,000
    Pa’s impact is £12,000
    The Smiths’s impact is £12,000
    The total impact is £6,000

    So, the causal attributions to the different agents are (‘total impacts’ / ‘specific impact’)

    Ma: (-)300%
    Pa: 200%
    Smiths: 200%
    Total: 100%

    Ma + Pa: (-)100%

    Now, since the question asks for the causal attribution to the Jones family as a whole, the answer is (-)100%. This question allows one to compare the total causal contribution of the two families through lumping together their elements, *assuming* they are all genuine causal elements.

    But maybe they are not all causal elements. Maybe Ma Jones is a feedback *effect* to the variations in account balance (rather than to the total balance, so it isn’t perfectly analogous with the ocean sink response). She is a passive sink who dynamically adjust her withdrawals to make them always 75% of the external monthly impacts on the account balance. Only because she is personalized as a human being are we forgetting that her “actions” could be analogous to natural effects in a dynamical system.

    In that case, Ma Jones doesn’t have any independent effects at all. She is a cog in the machine, as it were; she is merely responding passively to external causes.

    So, under those assumption, the causal attribution runs thus:

    Ma (ocean+biosphere): 0%
    Pa (volcano): 50%
    Smiths (mankind): 50%
    Ma + Pa (nature): 50%

    Notice that both possible analyses work with the same definition of a partial causal attribution, as the particular impact from an agent divided by the impacts from all agents (and disqualifying from independent agency mere dynamical responses).

  91. Pierre-Normand Houle says:

    PNH: “So, the causal attributions to the different agents are (‘total impacts’ / ‘specific impact’)(sic)”
    Should read: “specific/total”, of course.

  92. Rick,
    I’m not sure I really get what you’re getting at. One could argue that there is only nature and that all that we do is simply natural. The problem with that is that we are conscious and are able to understand the consequences of our actions. Hence, we are capable of making decisions as to what we should do in future and whether or not a particular pathway carries the risk of outcomes that would be worth avoiding (or, how much we should spend so as to minimise these outcomes).

    In order to do that we have to measure the BAD and the GOOD, and then net them.

    I have a problem with this that I tried to explain here. Few agreed with me 🙂 I do think that there is a difference between GOOD things that in intended (the GOOD outcome of getting energy to use) and GOOD things that might happen, but aren’t intended.

    Consider the following. Let’s say we have two possible future pathways, one in which we continue to generate energy via fossil fuels, one where we don’t. In both pathways the energy we generated is an intended GOOD outcome. In the fossil fuel pathway, we also have the risk of severe negative outcomes and the possibility of some unintended positive outcomes. In the non-fossil fuel pathway, we have the possibility that generating energy via non-fossil fuel systems is expensive and that it hampers economic growth, but we avoid the possibly bad outcomes associated with fossil fuel use. We also do not encounter the unintended but possible good outcomes. Should the latter count? Well, they weren’t intended (we don’t burn fossil fuels so as to generate possible good outcomes from climate change) and if we follow a different pathway, we will never really know if they would have actually happened. We will, however, know that we’ve avoided the bad outcomes. So, it’s not clear to me that the possible (but uncertain and unintended) good outcomes really play a role in the decision making. Others, however, seem to disagree 🙂

  93. paulski0 says:

    I’ll try another way of explaining Pierre-Normand’s point, though he may argue this has already been said:

    Firstly, there are natural carbon sinks which are entirely independent from natural carbon sources. As we see with the 50% airborne fraction figure, we can expect those independent natural sinks to take up increasing amounts of carbon from increasing emissions/concentrations regardless of natural or anthropogenic source.

    Think about a scenario in which a natural source – let’s call it unicorn farts – was, unbeknownst to us, coincidentally emitting increasing amounts of CO2 exactly in-line with anthropogenic emissions. Let’s assume actual airborne fraction is constant so the current rate of atmospheric increase is about 4ppm. Since anthropogenic emissions total equivalent 4ppm the mass balance argument would say the overall natural contribution must be net zero and airborne fraction is 100%. This would be arguably correct, but misleading/not useful since the rate of atmospheric increase is double what it would be without the contribution from unicorn farts.

  94. izen says:

    Senario 1. pre-industrial/paleoclimate, stable carbon cycle.

    Human CO2 emissions/sources ~ 0
    Human CO2 sinks ~ 0
    Natural sources +200Gt
    Natural sinks -200GT

    Atmospheric CO2 level static.

    Senario 2. Human emissions from burning fossil fuel +carbon cycle feedbacks increasing turnover and sinks.

    Human CO2 emissions/sources +10GT
    Human CO2 sinks ~ 0
    Natural sources +220Gt
    Natural sinks -225GT

    Atmospheric CO2 levels increasing by 5Gt.

  95. dikranmarsupial says:

    Pierre-Normand “Now, since the question asks for the causal attribution to the Jones family as a whole, the answer is (-)100%.”

    Right, would you say that the Jones family (as a whole) is causing the rise or opposing the rise?

    BTW brief and direct answers are more likely to produce progress, much of what you wrote is not relevant to the question that was actually asked and hence is likely to derail the discussion and make it difficult to reach agreement on the first point.

  96. RickA says:

    izen:

    Yes – in your scenario 2 – why is not human CO2 sinks considered 5GT.

    But for our 10GT of emissions, the natural sinks would not have expanded by 5GT.

    If the natural sink expansion is not our “fault”, than why is the warming and sea level rise our “fault”.

    It just seems to me that we have to be consistent – and by not including a Ua term in the mass balance equation, I don’t think we are being consistent.

  97. dikranmarsupial says:

    Pierre-Normand wrote:

    “In that case, Ma Jones doesn’t have any independent effects at all. She is a cog in the machine, as it were; she is merely responding passively to external causes.

    So, under those assumption, the causal attribution runs thus:

    Ma (ocean+biosphere): 0%
    Pa (volcano): 50%
    Smiths (mankind): 50%
    Ma + Pa (nature): 50%”

    O.K., I’ll allow you to divert the discussion. So lets say that Ma is just a cog in the machine and is adjusting here transactions in response to the rising balance. Does that mean that at the end of the year, when the account is closed, it would be fair to split the balance 50-50 between the Smiths and the Jones?

  98. dikranmarsupial says:

    RickA Ua represents uptake of co2 from the atmosphere via artificial processes. This is essentially zero, we are not currently doing any meaningfull amounts of sequestration.

  99. The increase in uptake of CO2 by nature is indeed our “fault”, but I don’t think that that then allows us to regard this as some kind of anthropogenic sink. As Dikran suggest, an anthropogenic sink would be us actively removing CO2, not relying on nature to do it for us.

  100. Pierre-Normand Houle says:

    ATTP & Dikran,

    The way I am using the general concept of causal attribution is the same way the IPCC is using it for the attribution of the recent rise in surface temperature. Though the topic is different, the underlying concept of a cause (e.g. a variation in Solar forcing) and a causal agent (e.g. the Sun) are the same.

    The way you two are using it to justify a 100% causal attribution to mankind, in the case of the atmospheric CO2 concentration increase over some recent period, is to consider the counterfactual conditional question: Would a rise still have occurred if we hadn’t contributed to it? If the answer is no, then you conclude that nature’s contributed nothing to the increase and the anthropogenic component is 100% since it is overwhelming the opposing natural tendency. For you, it’s an all or nothing affair, so long as nature’s total contribution has been to oppose our intervention, then we are 100% responsible for the increase, and nature merely is “actively opposing” our action (as Dikranmarsupial puts it).

    Consider the case of the attribution for the surface temperature rise. The IPCC looks at all the different forcings, both anthropogenic and natural, and isolates their separate impacts (e.g. with ensemble modeling, averaging out natural variability). The model results also are compared with the surface temperature record. This provides a hint at natural variability’s actual contribution to the rise. More complex analyses are also done; if we are to trust Kosaka and Xie, for instance, the natural component (natural forcings + ENSO variability) to recent surface warming (since 1950?) is negative. We conclude that the anthropogenic attribution is larger than 100% and Judith’s head explodes.

    But this conclusion appears inconsistent with your understanding of causal attributions. It is sufficient, on your view, to know that if we were to remove our causal contribution to the temperature increase (which is the creation of the enhanced greenhouse effect), which is proven to overwhelm nature’s propensity to cool the Earth surface (the Planck response), the Earth would begin to cool. That is, if we would restore the atmospheric CO2 concentration to anything near 310ppm (which we can do in models) the Earth would cool down rapidly. From this, you would conclude that the anthropogenic attribution since 1950 must be 100%. That would be equally true, on your view, even if Kosaka and Xie had found out that nature’s net contribution had been positive from 1950 until now.

    By contrast, on my view of causal attribution, the relevant question to ask, regarding the anthropogenic attribution to either temperature of CO2 concentration, is the following question: What is nature’s causal contribution over and above our own causal contribution. In the case of temperature, this is a question about the separable impact of natural forcing changes and internal natural variability, We need something like Kosala and Xie’s analysis to answer the question. And the result can either be more than 100%, or less and 100%, in spite of the fact that under your own peculiar interpretation of “causal contribution” the impact of nature has only been to resist our warming influence (the Planck response). We also need this sophistication in order to do meaningful CO2 attributions, though the evidence is rather straightforward and incontrovertible that our contribution is very close to 100%. That’s because natural causal candidates are easily ruled out on independent grounds. But it could be a little less or a little more, irrespective of the mass balance argument and of the fact that we are overwhelming “nature”. In counterfactual scenarios, it could be much less or much more than 100%.

  101. Pierre,

    The way I am using the general concept of causal attribution is the same way the IPCC is using it for the attribution of the recent rise in surface temperature. Though the topic is different, the underlying concept of a cause (e.g. a variation in Solar forcing) and a causal agent (e.g. the Sun) are the same.

    Except, in this context, given the information we have, nature, in total, is a net sink. So, yes, we agree that the role of nature is to mediate the rate at which it rises, but that it is rising is entirely anthropogenic.

    If you want to then compare that to the IPCC attribution statement, it would be comparable if natural influences could only produce cooling.

  102. RickA says:

    ATTP:

    I understand your point of view.

    I just think we are being inconsistent.

    If we get the blame – we should also get the credit (for things we cause).

    Again – turn it around.

    Say we have two years of much greater than average volcanism and we experience .5C of cooling over that period.

    Do we get credit for that?

    I would normally say no – because we didn’t cause it.

    But if we don’t get credit for stuff we cause and it goes into Natures’s column – than why wouldn’t we get credit for the cooling caused by nature (when things reverse – if they reverse)?

    We should be consistent and get the blame for what we cause,(BAD) as well as the credit for what we cause (GOOD).

    Otherwise – it is a heads we lose, tails we lose proposition.

  103. dikranmarsupial says:

    Pierre-Normand I don’t think that argument is valid. IIUC in attributing the warming to anthropogenic and natural forcings, the feedback mechanisms are applied to the natural forcings as well as the anthropogenic ones in just the same way.

    A direct answer to my question would be appreciated.

  104. If we get the blame – we should also get the credit (for things we cause).

    We should be consistent and get the blame for what we cause,(BAD) as well as the credit for what we cause (GOOD).

    I don’t think causing ocean acidification is something about which we should be proud.

    However, again, this isn’t really about good or bad. It’s about whether or not the rise is anthropogenic.

  105. Pierre-Normand Houle says:

    “Right, would you say that the Jones family (as a whole) is causing the rise or opposing the rise?”

    Yes it is opposing the rise. For the umpteenth time, yes, yes, yes, the Jones family is opposing the rise. The issue between us is what can be validly deduced from this commonly agreed upon premise. Of course you chose to ignored my argument *again*.

  106. dikranmarsupial says:

    Right so the Jones family are causing 50% of the rise (according to your causal attribution method) but they are opposing the rise?

    (note I am not ignoring your argument, nor have I been, I am just trying to point out that it is at best “counterintuitive).

  107. Pierre-Normand Houle says:

    dikranmarsupial: “O.K., I’ll allow you to divert the discussion. So lets say that Ma is just a cog in the machine and is adjusting here transactions in response to the rising balance. Does that mean that at the end of the year, when the account is closed, it would be fair to split the balance 50-50 between the Smiths and the Jones?”

    Yes, of course. Both Pa Jones and the Smith family contributed equally. And Ma Jones doesn’t care. She’s just a natural sink who happen to live in Pa’s premise. He’s not responsible for her any more than a super-volcano can be blamed for the existence of the oceans.

  108. dikranmarsupial says:

    “Yes, of course. Both Pa Jones and the Smith family contributed equally. ”

    Sorry, that is ridiculous. The Smiths have deposited £12,000 and withdrawn nothing, and the Jones have deposited £12,000 and withdrawn £18,000, and you think it would be fair for the Jones’ to be given £3,000 more? That would leave the Smiths with £6,000 pounds and the Jones with £24,000 at the end of the year. In what sense is that fair?

    “She’s just a natural sink who happen to live in Pa’s premise. He’s not responsible for her any more than a super-volcano can be blamed for the existence of the oceans.”

    Note the shift here from the Jones’ to just looking at Pa. As I said you keep ignoring the sinks (in this case Ma).

  109. dikranmarsupial says:

    Sorry the £3000 should be £6000 and the £24,000 should be £18,000 – long day!

  110. Pierre-Normand Houle says:

    dikranmarsupial: “Right so the Jones family are causing 50% of the rise (according to your causal attribution method) but they are opposing the rise?”

    No. They are collectively opposing the rise, because “they” (rather misleadingly) include the passive natural sinks. It is a separable causal agent — Pa Jones — who is attributed part of the causal attribution. When you speak of “nature” as a whole, you include the sink responses. When I myself speaks of the “natural causal contributions”, I am singling out the natural causal *agents*, just as the IPCC does for the natural part of the attribution of surface temperature increase. The IPCC attribution only includes the natural forcings. It doesn’t include the Planck response as a negative causal contributor just because the Planck response also is “natural”.

    “(note I am not ignoring your argument, nor have I been, I am just trying to point out that it is at best “counterintuitive).””

    Fair enough.

  111. dikranmarsupial says:

    sorry my arithmetic has failed for the day. The Smiths ends up with £3000 and Joneses with £21,000, in a fair settlement according to Pierre-Normands “causal attribution” scheme.

  112. dikranmarsupial says:

    Pierre, this is getting tiresome. The mass balance argument relates to the collective behaviour of the natural carbon cycle, yet you keep picking out individual components.

    You have said that the Jones family are opposing the rise. You have also said that the Jones family “Ma + Pa (nature): 50%” are causing 50% of the increase. Those are both statements you have made. The fact they are contradictory suggests there is a problem with your causal attribution scheme.

  113. Pierre-Normand Houle says:

    dikranmarsupial wrote: “Note the shift here from the Jones’ to just looking at Pa. As I said you keep ignoring the sinks (in this case Ma).”

    I am not ignoring the natural sinks. I am resisting your intimations to lump together the passive natural sinks with the natural causal agents. Just because I am not conflating agents and passive sinks (and feedbacks), or forcings and responses, doesn’t mean that I am ignoring them. I am rather arguing that they are not proper subjects of independent causal attribution.

  114. dikranmarsupial says:

    “I am resisting your intimations to lump together the passive natural sinks with the natural causal agents.”

    They should be lumped together. Note that if you do lump them together then there is no contradiction. The natural environment is opposing the rise. Man is causing 200% of the rise, nature is causing -100%. Applied to the Smith-Jones analogy, according to my scheme the fair solution would be for the Smiths to keep all of the remaining balance (indeed the Jones should pay some back). No contradiction. Unlike your scheme. Mostly in science, we tend to favour methods that don’t lead to contradictions, rather than those that do.

  115. > Think about a scenario in which a natural source – let’s call it unicorn farts – was, unbeknownst to us, coincidentally emitting increasing amounts of CO2 exactly in-line with anthropogenic emissions.

    Accountants usually don’t balance secret accounts they ignore.

    In other words, cf.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760349

    ***

    > The issue between us is what can be validly deduced from this commonly agreed upon premise.

    And I’ve shown many times that your own argument is invalid.

    ***

    > Of course you chose to ignored my argument *again*.

    False. This has been covered a while ago:

    I’m going to tell you a little secret: you’re exploiting the composition fallacy. It fails, because the fact that the whole of the natural carbon cycle is net negative doesn’t imply the same for all the processes within it. DM has never made that inference, and it’s all yours.

    In accounting, what you’re trying to sell can get you in jail. Ma wouldn’t be proud: she never wanted her sons to be accountants.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760422

    Your tone toward me changed around that time, Pierre-Normand. I hope we both know why.

    Please let me rest.

  116. Pierre,
    Since you brought up the IPCC attribution statement, consider the following. Imagine temperatures rose every year, but that the rate varied because of natural variability, and the rate never exceeded the maximum possible anthropogenic contribution. Now, there may be some natural contributions that could cause warming, and others that cause cooling, but – overall – the natural contribution is always to be a net cooling effect. Would you regard the warming as all anthropogenic, or only partly anthropogenic?

  117. Eli Rabett says:

    Perhaps too late, but if you posit that there are significant natural causes of the rise of CO2 concentration you have to say what they are, and in the case of all that have been run up the flag pole there are additional effects. For example volcanoes do not emit pure CO2 but also significant sulfur dioxide, particulates etc. That has obvious consequences.

  118. Pierre-Normand Houle says:

    dikranmarsupial: “You have said that the Jones family are opposing the rise. You have also said that the Jones family “Ma + Pa (nature): 50%” are causing 50% of the increase. Those are both statements you have made. The fact they are contradictory suggests there is a problem with your causal attribution scheme.”

    If you had read my post a little more carefully, you would have seem that those two contradictory conclusions are drawn in two separate sections (as I had announced that I would do) on the basis of two different assumptions regarding the underlying dynamical structure of the system. In the first analysis, Ma was considered to be an independent causal agent, and under the second analysis she was postulated to be a passive response to all the other genuine causal agents (“forcings”) — everyone else in both families — within the whole dynamical system.

  119. Joshua says:

    Anders –

    Dikran and I would say that the rise is entirely due to person A since their contribution exceeds the rise. Pierre would say it’s mostly A but partly D, because D’s contribution is net positive.

    Really, is that accurate? That semantic point of contention is what you eggheads have been arguing about over these many comments over two blogs?

  120. Pierre-Normand Houle says:

    Some bunny wrote: “Perhaps too late, but if you posit that there are significant natural causes of the rise of CO2 concentration you have to say what they are, and in the case of all that have been run up the flag pole there are additional effects. For example volcanoes do not emit pure CO2 but also significant sulfur dioxide, particulates etc. That has obvious consequences.”

    This is common ground among all the participants to this discussion, Eli. What is at issue in this thread is the conclusions that can be drawn solely on the basis of the mass balance argument, even in counterfactual scenarios where there would be a super-volcano erupting and plenty of evidence that it is a significant source. Read my first post for a characterization of the disputed issue.

    https://andthentheresphysics.wordpress.com/2016/01/26/mass-balance/#comment-71578

  121. dikranmarsupial says:

    “If you had read my post a little more carefully, you would have seem that those two contradictory conclusions are drawn in two separate sections”

    Yes, that is the point, your causal attribution scheme (the second section) is inconsistent with common sense (the first section) which says that the Jones are opposing the rise as they are taking more money out than they are putting in.

    The scheme ATTP and I favour leads to no such inconsistency. We can look at the individual attributions without there being an inconsistency with common sense. Smiths contribute 200%, Pa Jones 200%, Ma Jones -300% total 100%. The Jones are still opposing the rise as their joint contribution is -100%.

    So which scheme is better, the one with the inconsistencies, or the one without?

  122. Pierre-Normand Houle says:

    ATTP wrote: “Since you brought up the IPCC attribution statement, consider the following. Imagine temperatures rose every year, but that the rate varied because of natural variability, and the rate never exceeded the maximum possible anthropogenic contribution. Now, there may be some natural contributions that could cause warming, and others that cause cooling, but – overall – the natural contribution is always to be a net cooling effect. Would you regard the warming as all anthropogenic, or only partly anthropogenic?”

    This was already covered in my comment on Kosaka and Xie (I guess you know the paper). The causal attribution would be larger than 100% anthropogenic (together with a negative natural contribution) at any time where the actual temperature would have been lower than the model ensemble.

  123. Pierre-Normand Houle says:

    “Yes, that is the point, your causal attribution scheme (the second section) is inconsistent with common sense (the first section) which says that the Jones are opposing the rise as they are taking more money out than they are putting in.”

    Yes, common sense balks at representing intentional behaviors of flesh and blood human being’s as metaphorical surrogates for dynamical system feedback responses. So what? That still doesn’t make it scientifically sound to conflate forcings and responses in causal analysis and effect attribution.

    Nevertheless, common folks would also find counter-intuitive your claim that the rise in atmospheric CO2 concentration would be 100% anthropogenic even in the case where a super-volcano would have had the impact to raise it 10% higher than it would have been as the mere result of our own impact.

  124. Really, is that accurate? That semantic point of contention is what you eggheads have been arguing about over these many comments over two blogs?

    Yes, I think it actually is 😉

  125. The Very Reverend Jebediah Hypotenuse says:

    The mass-balance argument is only one of many that disclose the main source of increased atmospheric CO2 as anthropogenic. Even if the mass-balance accounting is ignored, there is no good reason to doubt that humans are the overwhelming source.

    Other paths to the same conclusion:
    – isotope ratio of C13 / C14
    – and of O16 / O18
    – decline in atmospheric oxygen concentration
    – partial pressure of CO2 in ocean is increasing
    – etc.

    http://www.skepticalscience.com/anthrocarbon-brief.html

    http://www.skepticalscience.com/print.php?r=384

    Consilience of evidence rulz.

    Unless you want to say “Wow.” and just ignore all that…

  126. > That semantic point of contention is what you eggheads have been arguing about over these many comments over two blogs?

    I concur:

    I believe this point of contention is mostly semantic, for it implies various conceptions of causality, attribution, and perhaps accounting.

    ***

    Once you agree that nature’s a net sink, you can’t dispute that it makes sense to say that the rise in CO2 is anthropogenic, or that humans are responsible for it. The problem is the word “cause”:

    What does “people are causing this” mean? Does it mean people are responsible for all of the warming, most of the warming, some of the warming? “At least the majority of it” captures the consensus opinion, I believe. The possibility of the anthropogenic forcing being superimposed on a natural background cooling is not, as far as I know, excluded. Though it complicates the clarity of public communication, “more than all of it” is actually a possibility.

    http://initforthegold.blogspot.com/2015/01/more-than-all.html

    The semantic problems caused by causation goes back to Hume at the very least. Add to this percentages and even Judy can feign misunderstanding.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760775

  127. dikranmarsupial says:

    “Yes, common sense balks at representing intentional behaviors of flesh and blood human being’s as metaphorical surrogates for dynamical system feedback responses. ”

    methods for attribution ought to make common sense, and it is a bad idea to use a counterintuitive scheme just for CO2 that doesn’t agree with common sense in other applications. Note the scheme I provided agrees with common sense both when looking at the carbon cycle and when talking about bank accounts. Which is why mine is more sensible.

    “Nevertheless, common folks would also find counter-intuitive your claim that the rise in atmospheric CO2 concentration would be 100% anthropogenic even in the case where a super-volcano would have had the impact to raise it 10% higher than it would have been as the mere result of our own impact.”

    No, yet again, when you want to look at the individual sources and sinks, anthropogenic sources are responsible for 200% of the rise, not 100%. It is not the same question.

  128. > This was already covered in my comment on Kosaka and Xie (I guess you know the paper).

    Here:

    http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12534.html

    A comment:

    Like I said, my mind is blown.

    http://judithcurry.com/2013/08/28/pause-tied-to-equatorial-pacific-surface-cooling/

    Xie’s reaction confirms the “blown” bit.

  129. dikranmarsupial says:

    “Nevertheless, common folks would also find counter-intuitive your claim that the rise in atmospheric CO2 concentration would be 100% anthropogenic even in the case where a super-volcano would have had the impact to raise it 10% higher than it would have been as the mere result of our own impact.”

    As I keep pointing out, in that scenario the the levels are higher because the natural environment had opposed the rise less, not because it had caused part of the rise, the two things are not the same.

  130. Eli Rabett says:

    Even a super volcano leaves small traces. Sorry this whole thing is along the lines of if pigs were horses cows would fly.

  131. Pierre-Normand Houle says:

    dikranmarsupial: “So which scheme is better, the one with the inconsistencies, or the one without?”

    There is no inconsistency in my two analyses, because they are the analyses of two different systems. If your turn some part of a system that was formerly an independent agent (e.g. a forcing such as an active super-carbon-sequestering plant) into a mere feedback response (e.g. a passive carbon sink), then it is no longer the same physical system.

    Your causal attribution is consistent with the first system where Ma is a causal agent. But is is inconsistent with the second system where Ma is a feedback response — i.e. an effects rather than a cause. Unfortunately for your argument, it is the second system that is the proper analogy to the mankind/volcano/ocean scenario.

  132. dikranmarsupial says:

    “There is no inconsistency in my two analyses, because they are the analyses of two different systems. ”

    No, they aren’t they are both analyses of (analogies for) the carbon cycle.

  133. guthrie says:

    The foregoing posts indicate why it doesn’t matter what analogy or method you use, there are always people who disagree with it.

  134. Pierre-Normand Houle says:

    Eli: “Even a super volcano leaves small traces. Sorry this whole thing is along the lines of if pigs were horses cows would fly.”

    Of course it leaves traces. Mt Pinatubo left a trace. The question is whether the mass balance argument *alone* justifies the conclusion that the CO2 rise is 100% anthropogenic and positively rules out that it could be, say, 99.999% anthropogenic and 0.001% natural (owing to Mt Pinatubo). Some people here, not PNH to be sure, say that the mass balance argument rules that out. They say that, by definition, if the rate of anthropogenic emissions have been larger than the net rate of uptake by the whole of “nature” (including Mt Pinatubo), then this means that the CO2 rise was 100% anthropogenic.

  135. snarkrates says:

    Actually, mass balance can be taken quite a bit further. We know that whatever the source of the carbon coming into the system, it is enriched in C-12 compared to C-13 and C-14, because the C-12/C-13 ratio is increasing. This makes the situation more similar to Pa Jones daughter coming home suddenly flush with cash–but the cash is all in $2 bills. Pa Jones could perhaps be forgiven for wondering whether his daughter’s wealth might not have something to do with the strip club that just opened up down the block.

  136. Pierre-Normand Houle says:

    dikranmarsupial: “No, they aren’t they are both analyses of (analogies for) the carbon cycle.”

    Sure. But they describe models that have different causal structures. Else they would not yield different causal attributions. I have justified the adequacy of the second model for representing the causal structure of the mankind/super-volcano/ocean scenario. You have yet to justify the adequacy of the first model as a representation of the causal structure of this simple scenario, and/or provide a reason for disqualifying the second model in that same regard.

  137. dikranmarsupial says:

    “Sure. But they describe models that have different causal structures.”

    a model of the carbon cycle is not the carbon cycle.

    “I have justified the adequacy of the second model ”

    no you haven’t as I have pointed out, it leads to inconsistencies, unlike the “model” that allows negative contributions and contributions greater than 100%

    “You have yet to justify the adequacy of the first model as a representation of the causal structure of this simple scenario”

    This is because you are using “causal” in a non-standard manner. Feedback mechanisms are causal, there is a physical law underpinning them.

  138. Pierre-Normand Houle says:

    snarkrates: “Actually, mass balance can be taken quite a bit further. We know that whatever the source of the carbon coming into the system, it is enriched in C-12 compared to C-13 and C-14, because the C-12/C-13 ratio is increasing. This makes the situation more similar to Pa Jones daughter coming home suddenly flush with cash–but the cash is all in $2 bills. Pa Jones could perhaps be forgiven for wondering whether his daughter’s wealth might not have something to do with the strip club that just opened up down the block.”

    Indeed. However, in the simple banking analogy we already know what the “sources” and “sinks” are. We just don’t know what transactions are “forced” and what transactions are “feedbacks” responses. That isn’t specified in dikranmarsupial’s statement of the analogy.

  139. LurkerDan says:

    (Long time lurker)

    Let me start by saying I fully support the mainstream science of AGW and believe that the increase is atmospheric CO2 is approx 100% anthropogenic.

    But I have to defend Pierre here.

    You’re arguing cross purposes because you haven’t formalised the meaning of attribution.

    The mass balance argument works if you hold constant the mass in non atmospheric sinks and remove the anthro contribution. Total emissions are greater than atmospheric increase implying greater than 100% attribution (and net negative natural contribution). Fair enough and true for that definition of attribution.

    The alternative definition (that I find more natural) is to attribute to each source the difference between the current atmospheric mass, to that expected in the (counterfactual) scenario in which the source is absent.

    My guess by this definition would be ~100% anthro because I would expect equilibrium prior to human emissions and no net change in their absence. But I wouldn’t rule out a small natural contribution in either direction. Mass balance cant nail a 100% attribution by this definition.

    A bit like thermodynamics you need to say what you hold constant when you change something or you get different answers…

  140. The alternative definition (that I find more natural) is to attribute to each source the difference between the current atmospheric mass, to that expected in the (counterfactual) scenario in which the source is absent.

    Potentially, yes, and in the case of volcanoes that might be reasonable given that we have no reason to expect that volcanic activity should respond in some way to our emissions. However, what do you do if the source is permafrost release? If it were to occur it would be a net source of GHGs, but it would almost certainly be a response to warming and hence is really a carbon cycle feedback.

    To go back a step, though, if you do simply divide it up into “natural” and “anthropogenic” then one would simply conclude that it’s anthropogenic. Similarly, if we divide our warming into “natural” and “anthropogenic” we would presumably conclude that all the warming over some period was anthropogenic if the net natural influence was cooling, even if some aspect (the Sun, for example) would have produced a warming influence.

  141. Pierre-Normand Houle says:

    dikranmarsupial wrote: “a model of the carbon cycle is not the carbon cycle.”

    If it doesn’t include a rudimentary specification of the laws governing its evolution as a response to the input forcing scenarios, and doesn’t even identify the forced variables, then it is an incomplete model. It couldn’t possibly be run on a computer. And it furnished no basis for any sort of causal attribution regarding the real system allegedly modeled.

    “no you haven’t as I have pointed out, it leads to inconsistencies, unlike the “model” that allows negative contributions and contributions greater than 100%”

    They are two different models that would evolve differently under varying forcing scenarios. For two different models to yield different causal attributions is expected. That’s not an inconsistency.

    “This is because you are using “causal” in a non-standard manner. Feedback mechanisms are causal, there is a physical law underpinning them.”

    It is however standard in causal *attributions* not to credit the feedbacks with any share of the effect. That’s because the feedbacks are causally downstream from the forcings. We don’t say that the 20th century warming was 70% CO2 forcing, 10% solar forcing and 20% water vapor feedback, for instance. We leave water vapor out of the attribution because it isn’t an independent causal factor.

  142. Pierre-Normand Houle says:

    LurkerDan wrote: “Let me start by saying I fully support the mainstream science of AGW and believe that the increase is atmospheric CO2 is approx 100% anthropogenic.”

    Thanks for the unlurking, Dan 😉

  143. dikranmarsupial says:

    “You’re arguing cross purposes because you haven’t formalised the meaning of attribution. ”

    Agreed, which is partly why I try an make a distinction between the natural environment as a whole and the contribution of individual sources and sinks. I’m not sure it is clear the degree to which some natural sources/sinks act as feedback or forcings, which is also a problem. The problem I have is that Pierre’s definition too easily blurs the distinction between the natural carbon cycle as a whole, and the effect of its individual components (i.e. forgetting the sinks – just because the net sink is a feedback doesn’t mean it isn’t relevant to the attribution).

    “The alternative definition (that I find more natural) is to attribute to each source the difference between the current atmospheric mass, to that expected in the (counterfactual) scenario in which the source is absent.”

    In the case of volcanoes, in their absence, the carbon subducted into the mantle would never come back (mid ocean ridges are essentially linear volcanoes). It is not clear to me how far that would cause CO2 levels to fall, but it may well be a lot (which would overstate their contribution)!

    Is there any evidence that volcanic activity would have raised CO2 levels at all in the absence of anthropogenic emissions?

  144. dikranmarsupial says:

    ATTP wrote “To go back a step, though, if you do simply divide it up into “natural” and “anthropogenic” then one would simply conclude that it’s anthropogenic. Similarly, if we divide our warming into “natural” and “anthropogenic” we would presumably conclude that all the warming over some period was anthropogenic if the net natural influence was cooling, even if some aspect (the Sun, for example) would have produced a warming influence.”

    yes, that sounds sensible to me.

    Pierre wrote “Thanks for the unlurking, Dan ;-)” indeed, it was a good contribution!

  145. dikranmarsupial says:

    …of course without volcanoes, there wouldn’t be any subduction…

  146. Pierre-Normand Houle says:

    dikranmarsupial: “The problem I have is that Pierre’s definition too easily blurs the distinction between the natural carbon cycle as a whole, and the effect of its individual components (i.e. forgetting the sinks – just because the net sink is a feedback doesn’t mean it isn’t relevant to the attribution).”

    If the sinks respond differentially to the independent sources then, for sure, that complicates the attribution analysis. This is akin to the treatment in Marvel et al. (2015), where the varying efficacies of the different forcings are considered. That would also complicate the detailed attribution since not all the forcings trigger all the feebacks in the exact proportion of their individual magnitudes. Science would be so much simpler if we would all use your trademark method of causal attribution. We would simply notice that “nature” is actively opposing our attempts to drive the climate system out of whack and conclude that any significant effect that nevertheless occurs (e.g. large warming, large CO2 increase, etc.) is therefore 100% anthropogenic, and be done with it. The IPCC report would be much slimmer too.

  147. dikranmarsupial says:

    Pierre-Normand that wasn’t the distinction I was making (although I suspect it may well be true). Even if the feedback applies equally to anthropogenic and natural emissions, that doesn’t mean it is not relevant to the attribution.

    Defining the forcing relative to the pre-industrial period would help a bit. While volcanoes do produce their CO2 independent of the atmospheric circulation, the equilibrium atmospheric concentration is in part set by the background level of volcanic activity, so there would need to be a trend in volcanic activity for there to be any forcing. Would it not be better to view individual eruptions as stochastic noise (carbon-cycle weather)?

    “Science would be so much simpler if we would all use your trademark method of causal attribution. ”

    I am rather more concerned with public discussion of science here. Scientists have a tendency to use language in very specific ways that are misunderstood by the general public (“statistically significant” is an excellent example from my own field ;o). I’d say that “my” method of attribution is just the every day common sense interpretation.

    ” and conclude that any significant effect that nevertheless occurs (e.g. large warming, large CO2 increase, etc.) is therefore 100% anthropogenic, and be done with it.”

    No, that would be a mistake. 100% of the rise in CO2 does not imply that 100% of the warming is anthropogenic, and I don’t think anyone would claim that it does.

  148. Pierre-Normand Houle says:

    I must also note, Dikranmarsupial, that my method commits me to take the sinks into account and make a detailed analysis of them whereas you yourself are committed to ignoring them. That’s because if there is an independent natural cause for some sink being removed or acquiring a reduced capacity, or an increased capacity, then that would count for me as a natural cause of CO2 increase/decrease and figure in the attribution breakdown. But you would ignore variations in those sink capacities just as you must ignore any abnormal variation in natural sources because of your mass balance argument telling you that the atmospheric change is 100% anthropogenic anyway. How can you possibly claim not to ignore the sinks while making causal attributions? The only mention that you make of them is in order to justify your conclusion that “nature” as a whole is a net sink — isn’t contributing anything to the atmospheric CO2 concentration rise — and that therefore the natural contribution is invariably 0% regardless of the detailed behavior of the sinks.

  149. dikranmarsupial says:

    How about this as a compromise. We could say that the carbon cycle has a forced component (external perturbation) and an unforced component (which describes the response to the perturbation and stochastic noise). I would have no problem with the idea that the forcing is 99% anthropogenic and 1% natural (due to an increase in volcanic emissions over pre-industrial levels).

    This gets around a few problems, firstly it means that there is no inconsistency with the statement that the natural carbon cycle is opposing the rise in atmospheric CO2 (which it is). Secondly it gets around the difficulty to do with the definition of “causal” (the feedback mechanisms are causal), but Pierre-Normand appears to be using causal to mean something that isn’t a feedback. Lastly it makes it clear that the attribution only refers to the perturbation of the carbon cycle, not its overall behavior.

    The forcing would be defined relative to pre-industrial conditions.

  150. dikranmarsupial says:

    “I must also note, Dikranmarsupial, that my method commits me to take the sinks into account and make a detailed analysis of them whereas you yourself are committed to ignoring them. ”

    Nonsense, there is an explict term for sinks in the mass balance analysis, so they can hardly be ignored.

  151. Pierre-Normand Houle says:

    “No, that would be a mistake. 100% of the rise in CO2 does not imply that 100% of the warming is anthropogenic, and I don’t think anyone would claim that it does.”

    I don’t understand what you are trying to say here. The antecedent clause isn’t a complete proposition. You may have skipped a few words. You have long been arguing on the basis of the mass balance argument that so long as our emissions are larger than the rate of atmospheric CO2 accumulation, the resulting accumulation is 100% anthropogenic.

  152. dikranmarsupial says:

    my point is that just because 100% of the accumulation of CO2 is anthropogenic, that doesn’t imply that 100% of the warming is anthropogenic, and nobody would make that claim (except on the www, where there is always someone who will make any claim ;o).

  153. Yes, it’s not all CO2 🙂

  154. Pierre-Normand Houle says:

    “Nonsense, there is an explict term for sinks in the mass balance analysis, so they can hardly be ignored.”

    Yes, and your mass balance “analysis” reduces to the asking of the simple question “Is nature as a whole a net sink?”, and when the response is “yes” (and it always has been “yes” during the last couple hundred years) then the “analysis” of the individual sinks, for purpose of causal attributions, is over. Man 100%, Nature 0%.

  155. Pierre-Normand Houle says:

    Dikranmarsupial: “my point is that just because 100% of the accumulation of CO2 is anthropogenic, that doesn’t imply that 100% of the warming is anthropogenic, and nobody would make that claim (except on the www, where there is always someone who will make any claim ;o).”

    Apologies. I hadn’t registered you word “warming”. Time for me to rest. Good night/day.

  156. dikranmarsupial says:

    “Yes, and your mass balance “analysis” reduces to the asking of the simple question “Is nature as a whole a net sink?”

    which is impossible to do if you ignore the sinks, which is what you claimed I was “commited to”. I’m sorry, but I have had about enough of this.

    “(and it always has been “yes” during the last couple hundred years)”

    actually I rather doubt that is true, It has been true for the last fifty years, but there have been several in that time that came pretty close, so I suspect if you go back further, it would only be true in a long term average sense.

  157. Pierre-Normand Houle says:

    dikranmarsupial: “How about this as a compromise. We could say that the carbon cycle has a forced component (external perturbation) and an unforced component (which describes the response to the perturbation and stochastic noise). I would have no problem with the idea that the forcing is 99% anthropogenic and 1% natural (due to an increase in volcanic emissions over pre-industrial levels)”

    This is a compromise that I might be willing to make, considering that it is precisely my starting position 😉

  158. dikranmarsupial says:

    Fine, we agree then that the increase in atmospheric CO2 is anthropogenic and that the natural carbon cycle has opposed the rise (which is what I claimed the mass balance analysis establishes) but that not all of the carbon cycle forcing is necessarily anthropogenic (although the vast majority is, but this is not established by the mass balance analysis)?

  159. Pierre-Normand Houle says:

    Dikranmarsupial wrote: “which is impossible to do if you ignore the sinks,”

    No. You need not look at, nor study or analyse, any real physical sink whatsoever. You just look a the Mauna Loa curve, and estimate the cumulative anthropogenic emissions. That’s all. If our emissions are consistently larger than the rate of atmospheric CO2 accumulation, then you can deduce logically that nature as a whole (minus the atmosphere) is a net sink. This is the mass balance argument.

  160. Pierre-Normand Houle says:

    dikranmarsupial: “Fine, we agree then that the increase in atmospheric CO2 is anthropogenic and that the natural carbon cycle has opposed the rise (which is what I claimed the mass balance analysis establishes) but that not all of the carbon cycle forcing is necessarily anthropogenic (although the vast majority is, but this is not established by the mass balance analysis)?”

    That’s a deal. , and goodnight… for real this time.

  161. dikranmarsupial says:

    “No. You need not look at, nor study or analyse, any real physical sink whatsoever. ”

    That isn’t ignoring them. Ignoring them means not considering them at all in the analysis.

    The mass balance equation is not a model of the carbon cycle, it is a statement of a constraint that must apply to the carbon cycle that allows us to estimate the net natural flux. It is possible to make useful inferences based on observations and constraints without a full model. You do know that the terrestrial sink is often estimated as the residual from the mass balance equation?

  162. Pierre-Normand Houle says:

    I meant: “That’s a deal. ‘Handshake’, and goodnight… for real this time.”
    (WordPress had erased the ‘handshake’ because of surrounding bracket tags.)

  163. izen says:

    And the prize for one of the longest rallies I have seen in blog tennis goes to Dickran and P-Houle.

    It isn’t just semantics. The underlying problem is inconsistent concepts of causation. There is some utility in our enthusiasm for pruning complex, branched and looped causal networks into a simple, single, mono-directional causal link.

  164. > You’re arguing cross purposes because you haven’t formalised the meaning of attribution.

    No need. There’s this:

    without the consortium part, it no longer maps onto the anthropogenic-v-natural attribution question.

    And this:

    much of what you wrote is not relevant to the question that was actually asked and hence is likely to derail the discussion and make it difficult to reach agreement on the first point.

    There would not be any cross-purpose without gems like this one:

    This is begging all the questions. You can’t show that something doesn’t have an effect just because, combined with other things, the effects is reversed.

    Dikran is not begging Pierre-Normand’s question for the simple reason that he never purports to answer it, and is not required to do so to attribute minimal causation to an overall box. In fact, it’s the other way around: it is only by begging a full-blown attribution of everything that Pierre-Normand’s question makes sense. This may be the reason why he started by appealing to ignorance before switching to his composition fallacy.

    Worse, it could easily be possible to decompose furthermore the concept of sources, say by asking why we shouldn’t split an entity E with its sinks and its sources, or many sinks and many sources. A sorites might ensue, which is what Bartemis did with his Daemon. The most natural endpoint of Pierre-Normand’s quest is to attribute causality to all the sources (i.e. what cause more CO2) and all the sinks (i.e. what cause less CO2). Causation then becomes equivalent to being a source and a sink.

    Skepticism doesn’t win by dissolving all questions with overpowering requirements for knowledge claims. Neither should contrarians.

    ***

    Pierre-Normand keeps inserting his own question into Dikran’s mind. This has to stop. I think it’s safe to say that Dikran knows that he can’t attribute anything to what he doesn’t know. That’s not what he does.

    Basic boxology, guys. Dikran looks from the outside, while Pierre-Normand looks from the inside of the box. To use a more formal analogy, take a look at this:

    The explanation:

    These two machines have exactly the same behaviors. Moreover, A simulates B and B simulates A (we leave this as an exercise for the reader to verify). Nonetheless, these two machines are not bisimilar. To see this, suppose that in that in first round, B moves first, and moves from state e to state f. Then A can match this move by moving to state b. But now, suppose that in round 2, A moves first and moves to state d. In this case, B cannot match this move.

    Source: http://ptolemy.eecs.berkeley.edu/eecs20/week4/bisimulation.html

    Bisimulation is just a name for a very strong equivalence, and might be overkill for a whole planet with complex sinks and sources.

    ***

    > It isn’t just semantics. The underlying problem is inconsistent concepts of causation.

    I’m not sure they’re inconsistent, but even if they were, the problem would be exactly that: semantics. Conceptual analysis is a form of semantics.

    The best way to settle this would to inspect the question as an empirical matter. Ask people around and see how both frameworks fare. It would still be semantics, however.

  165. Brandon Gates says:

    Willard,

    That AGW is not inconsistent with opposite weather events only means that weather is not climate.

    Something which only applies under certain circumstances:

    https://archive.is/zxFMB

    —————

    2015 Global Temp, Or How Some Scientists Deliberately Mistook Weather For Climate

    Anthony Watts / January 23, 2016

    Here would be 10 ways to falsify AGW:

    Suddenly I remember you and I have discussed this before, thank you for the reminder. One very salient point:

    As a matter of fact, the ‘AGW-hypothesis’ is not a hypothesis in the Popperian sense. The human impact on climate is a theory, supported by many hypotheses, each of them tested according to widely accepted scientific standards. Just as Popper and his successors in the philosophy of science would have wanted.

    Which I allude to in: [Winter Storm Judas] is not inconsistent with global warming irrespective of cause. Some Denizens are only renowned for paying attention to detail and nuance when it suits their purposes.

    8. A source of heat in the climate system that we do not know yet
    9. A fundamental flaw in the scientific understanding of radiation physics or thermodynamics
    10. CO2 molecules appear to behave differently in the wild, than they do in a laboratory

    8 and 9 are particularly strong IMO. 10 is one which has been used against me (by way of assertion sans substantive evidence, “you cannot assume CO2 behaves the same way in the actual system as it does in the lab”), and is why Hans Custers included it.

    #7 is apropos blizzards in a warming climate due to any cause: 7. Evidence of a substantial fall of relative humidity with rising temperature.

    … though I think it’s cleaner to use specific humidity directly for this argument as it tends to confirm rise/fall in absolute temps due to any cause.

    I have some problems with the lead item: 1. A drop in global temperatures for some period of time to the level of 50 years ago or longer, without a clear cause

    Victor Venema makes a similar argument in his post referenced by Custers: If there would be an unexplained temperature drop of one degree and it would stay there for a decade, the theory is completely dead. If the same thing happens to the ocean heat content, the theory is dead within a year.

    So I pretty much agree that those scenarios would severely challenge the radiative theory of AGW, but it’s difficult to imagine such a dramatic reversal occurring AND be inexplicable. I’ll further note that some Denizens are already arguing that “climate has changed in the past” and implying that nobody knows why. As written, I think these statements in isolation set an urealistically high bar of falsification, if not verging on being non-falsifiable.

    Much better I think to say that an explained reversal of such magnitude would kill AGW theory — which is what item 8 argues — especially in conjunction with item 9, and by extension this item: 5. Warming of the stratosphere

    I think a good challenge for Denizens is: build a model with CMIP5-level output parameters which better explains paleo and modern observations without invoking atmospheric radiative fluxes or mathematically contrived pseudo-perodic oscillators and you’ll have my full and undivided attention.

    Here’s another example of a falsifiable claim: “The ‘hiatus’ will continue at least another decade.”

    Highly sensitive to temperature anomaly index of record. Here’s another one: http://www1.ncdc.noaa.gov/pub/data/cmb/bams-sotc/climate-assessment-2008-lo-rez.pdf

    “Near-zero and even negative trends are common for intervals of a decade or less in the simulations, due to the model’s internal climate variability. The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.”

    Vintage 2008.

  166. Tom Curtis says:

    Dikran, the experiments are set an a logically possible world, not in this one. The thought experiment involving Professors X and Y shows that there exists logically consistent worlds in which the premises of the Mass Balance argument are true, and the conclusion false. Ergo the Mass Balance argument is not a deductively valid inference. Nor is it an inductively valid inference in abstract, absent quantification of the range of possible worlds in which Henry’s Law (or relevantly equivalent) applies.

    The Mass Balance argument is inductively valid in this world when coupled with the observations supporting Henry’s Law. Indeed, I would go further and say it is the strongest of the various lines of evidence I point to in Climate Change Cluedo. Nor would I urge these objections against your published paper, as you are entitled to assume well established and well known physical laws are true in peer reviewed literature.

    Primarily my intent in pointing out this objection to the argument is that when you face a denier who simply rejects the Mass Balance argument, you can point out that there are falsified conditions that would allow the premises to not follow from their conclusions, which then confronts them with the fact that they are implicitly denying a well confirmed (by laboratory experiment) empirical law; and rhetorically pushes them to specify the conditions that they think actually exist that make the mass balance argument unreliable. (I also have a small interest in showing the mass balance argument does not escape the Duhem-Quine thesis.)

    Finally, regarding equilibrium – in the laboratory flasks are small relative to the size of oceans. Therefore the time to equilibrium will be shorter even than the time to atmosphere/surface ocean equilibrium (which is on the order of a year). Ergo the case of equilibrium values with laboratory flasks is the relevant case for comparison with the short term response to injecting CO2 into the atmosphere. I am not sure that is particularly relevant, however, as the time to full ocean equilibrium (of the order of 300 years) will still leave a substantial excess CO2 content in the atmosphere as a result of anthropogenic emissions. Ergo the mass balance argument would be as valid three hundred years after the cessation of net anthropogenic emissions just as much as it is now.

    As a point of clarification, in the thought experiment, Professor X does no experiments with flasks. Rather he quantifies anthropogenic emissions, determines the mass in GtC per ppm of CO2 in the atmosphere, takes the equivalent of the Keeling Curve and does the maths. He then applies the mass balance argument with the intuitively obvious result. Professor Y’s experiments show the intuitively obvious result to be false because, in this imaginary world, across a broad range of temperatures, pCO2 above liquid water is a direct function of the temperature of the water regardless of additional emissions of CO2 (across a broad range of emission levels).

  167. Pierre-Normand Houle says:

    Willard wrote: “The most natural endpoint of Pierre-Normand’s quest is to attribute causality to all the sources (i.e. what cause more CO2) and all the sinks (i.e. what cause less CO2). Causation then becomes equivalent to being a source and a sink.”

    That was a charge that dikranmarsupial had also made against my view very early on. But I am, and always have been, only considering anthropogenic or natural events (evenhandedly) that can be singled out as independent sources of variation in, or disruption of, a long term stable carbon cycle evolution (i.e.. a steady state). (Search for the word “disruption” in this thread or the previous one at Judith Curry’s blog). This is analogous, and just as sensible as, the concept of a forcing *change* as an independent cause of climate change, and it is, likewise, time-scale relative. (Compare what counts as forcing or feedback in climate change episodes over different time-scales).

    In our new agreed compromise position, dikranmarsupial has granted me this causal interpretation of the ‘forced’ components (either natural or anthropogenic) of the carbon cycle evolution. (The internal stochastic sources of change are more difficult to tease out, but can be estimated with the use of models, as in the example of Kosaka and Xie discussed earlier (to isolate the effect of ENSO) or simply looking at residuals from the long term trend clearly itself assignable to known forcings (natural+anthropogenic.)

    Nothing commits me to credit all the stable sources and sinks in the system as causal contributors in the attributions of a long term *change*. A super-volcano that produces a discernible bump in the Mauna Loa record counts. Ordinary volcanoes, and the natural sequestering processes that are balancing their contributions out, don’t count in the attribution of the *change* in atmospheric CO2 concentration that occurs in a time scale of mere centuries or decades.

  168. Pierre-Normand Houle says:

    dikranmarsupial wrote: “The mass balance equation is not a model of the carbon cycle, it is a statement of a constraint that must apply to the carbon cycle that allows us to estimate the net natural flux. It is possible to make useful inferences based on observations and constraints without a full model.”

    That also correspond to my starting position. So you can feel free to incorporate it to our joint “compromise” statement 😉

  169. Pierre-Normand Houle says:

    dikranmarsupial: “Fine, we agree then that the increase in atmospheric CO2 is anthropogenic and that the natural carbon cycle has opposed the rise (which is what I claimed the mass balance analysis establishes) but that not all of the carbon cycle forcing is necessarily anthropogenic (although the vast majority is, but this is not established by the mass balance analysis)?”

    That’s exactly right. The first statement is slightly ambiguous though. It wouldn’t be pedantic to explain why. It is right in the sense that, were it not for the dominant anthropogenic component, there would not have been a positive increase at all. It doesn’t entail, though, that the residual natural ‘forcing’ component has been negative.

    This had seemed counterintuitive to some. If we are entirely responsible for the *fact* that atmospheric CO2 concentrations is going up, and “nature” is actively opposing this rise, can the natural forcing component nevertheless also be positive? Yes it can. It is just the sum total of the natural positive forcing components *and* the passive sink response that is proven by the mass balance argument to be negative, in this case.

  170. Michael Hauber says:

    I believe we are clearly to blame for the co2 increase, but I think the mass balance argument is false. Imagine a world different to our own, where Solar activity increases temperature instantaneously, and then stays constant at the new higher level, and mankind also instantaneously emits a pulse of Co2 which is very small relative to the combined capacity of the ocean and atmosphere. In this world the final equilibrium level of Co2 in the atmosphere will be dominated by the equilibrium set by the temperature, which is controlled by the solar activity. There will also be a slightly higher amount of Co2 in the atmosphere due to the addition of extra Co2 to the combined ocean + atmosphere. If the pulse is large enough to put the atmospheric concentration above this final equilibrium then Co2 will flow out of the atmosphere into the natural ‘sink’ being the ocean, but the dominant source of increase of atmospheric Co2 will be the increase in temperature driven by the ‘natural’ increase in solar activity.

    An analogy would be a narrow tank of water with surface area 1 square meter connected by pipe to a much larger body of water with surface area 1000 square meters. If 1 meter of water is added to the small tank the same time that 1 centimeter of water is added to the larger body water will flow out of the small tank into the larger tank. However the final increase in height if water is added to both tanks is ten times as much as the increase in height that would result if water was added only to the small tank.

  171. Michael,
    But we’re not talking about a scenario where we simply emit a pulse. You’re right that if we emit a pulse and something else causes temperatures to rise, we could settle at a new equilibrium which would be dominated by the rise in temperature. What we’re considering is a scenario in which atmospheric CO2 rises year on year and we emit CO2 year on year, and in which the rise is smaller than our emissions.

  172. dikranmarsupial says:

    Pierre-Normand wrote “That’s exactly right. The first statement is slightly ambiguous though. It wouldn’t be pedantic to explain why. It is right in the sense that, were it not for the dominant anthropogenic component, there would not have been a positive increase at all. It doesn’t entail, though, that the residual natural ‘forcing’ component has been negative.”

    Yes, this is why the inconsistency in your causal attribution scheme goes away when it is used to describe the forcing rather than the increase in atmospheric CO2, the two are different concepts. Personally I think the forcing is a rather esoteric concept that isn’t terribly relevant to policymakers in this case, but more of scientific interest.

    I still don’t get Tom’s argument, one prof. is looking at the system in action, the other is looking at a system at equilibrium. The second prof therefore hasn’t seen how the system opposed the rise in CO2 above the water because he only looks at it after it has equilibriated. However, I have run out of enthusiasm for this discussion for the moment, but Tom’s comments are food for thought (as usual).

  173. Michael Hauber says:

    ATTP, one counter-example disproves a theory, no matter how like or unlike the counter-example is to the current real world. The question then is can the theory be modified to dissallow the counter-example but still apply to the real world?

  174. ATTP,
    The mass-balance argument isn’t really a theory. It’s really just an observation. The observation is that nature is a net sink and anthropogenic emissions are a net source. Creating an alternative that isn’t the same as the current situation, does not really disprove it. As I think Tom is pointing out, one could construct a world where it would not necessarily indicate that anthropogenic emissions were the source, but in any world with the same laws of nature as our own, it does.

  175. Pierre-Normand Houle says:

    Dikranmarupial: “Yes, this is why the inconsistency in your causal attribution scheme goes away when it is used to describe the forcing rather than the increase in atmospheric CO2, the two are different concepts. Personally I think the forcing is a rather esoteric concept that isn’t terribly relevant to policymakers in this case, but more of scientific interest.”

    On the contrary, since all the forcings have separable impacts, and the sink response (negative feedback) tends to dampen those impacts indiscriminately (i.e. in direct proportion to them), it is highly misleading to interpret the natural sinks as only mitigating the natural forcings just because they are both “natural”.

    This ought to be obvious when you consider the attributions of 20th century surface warming. The feedbacks that amplify both the natural and anthropogenic forcings also constitute a natural response to the forcings. If you are going to credit the natural feedback amplification of the forcings entirely to nature, then you are going to conclude that the anthropogenic attribution of 20th century warming only is the direct response to the CO2 forcing with no feedback. This is the impact that we would have had alone if ECS had been something like 1.2°C/CO2 doubling. The rest of the warming, which includes the direct impact of the natural forcings, and the total feedback amplification (indirect impacts) of both the natural and anthropogenic forcings, you would credit them all to nature. But this would be absurd for the purpose of attributions. It is no less absurd in the case of the carbon cycle.

    Imagine if ECS were 6°C/CO2 and the forcing 100% anthropogenic (one doubling of CO2 say). At equilibrium you would say that the attribution for the 6°C warming is 20% anthropogenic and 80% natural.

  176. The feedbacks that amplify both the natural and anthropogenic forcings also constitute a natural response to the forcings. If you are going to credit the natural feedback amplification of the forcings entirely to nature, then you are going to conclude that the anthropogenic attribution of 20th century warming only is the direct response to the CO2 forcing with no feedback.

    Hold on, I think this is mixing things up. In the context of the carbon cycle, a feedback would be something like permafrost release, or the change in ocean/biosphere uptake as temperatures rise. So, if you want to be consistent, the feedback response in the carbon cycle would be the difference between the natural uptake rate if we had not warmed, and what it is given that we’ve warmed. I don’t think you can regard the entire natural uptake rate as a feedback.

  177. Pierre-Normand Houle says:

    ATTP: “Hold on, I think this is mixing things up. In the context of the carbon cycle, a feedback would be something like permafrost release, or the change in ocean/biosphere uptake as temperatures rise. So, if you want to be consistent, the feedback response in the carbon cycle would be the difference between the natural uptake rate if we had not warmed, and what it is given that we’ve warmed. I don’t think you can regard the entire natural uptake rate as a feedback.”

    For the analogy to work better we would merely have to consider steady states in both cases. When CO2 is added to the atmosphere, surface temperature rises until radiative balance is restored and a steady state (in all the energy fluxes at all levels) is achieved. So, we could look at step increase in the rate of anthropogenic emissions (or volcanic emissions) to a higher rate and wait until a new steady state is achieved. A difference remains that when steady state is achieved, in this case, the sinks (negative feedbacks) would be filling up at constant rate, but they don’t have an infinite capacity.

    Dikranmarsupial attribution scheme makes him credit the increase in the rate of the natural sink uptake with mitigating *only* the causal attribution the natural sources (causes) of the increase in atmospheric CO2 concentrations as if only the natural causes were thus dampened and not also the human emissions.

    Hence, in a scenario where atmospheric CO2 concentration would have been stable for centuries, and then, humans and some super-volcano would each have dumped 10 GtCO2 into the atmosphere, and the resulting increase in atmospheric CO2 mass would have been 9.999Gt (because the sinks removed 10.001Gt), dikranmarsupial would say that the increase is 100% anthropogenic (just because “nature” as a whole “merely resisted” the anthropogenic increase).

    Does that seem like a reasonable causal attribution of the increase to you?

    I would rather say that mankind and the volcano each are causally responsible for 50% of the increase, and the increase has ended up being equal to only half the combined emissions just because of the sink response to both of them. There is no need to ascribe any percentage of the causal attribution to the sink response since it is an effect, not a cause of the atmospheric CO2 increase. But even if one would insist with accounting causally with the efficacy of the passive sink, one must do so separately from the efficacy of the agents. What is absurd is to sum up the natural agents and sinks as one single natural “cause” and therefore conclude that humans caused all the CO2 increase, in this scenario, in spite of the fact that the super-volcano and humans contributed the same amount of CO2 at the exact same rate.

  178. Pierre,
    But I think your scenario is not physically plausible in the sense that if volcanoes suddenly started emitting 10GtC per year more than is being subducted into the lithosphere, atmospheric concentrations would rise even in the absence of anthropogenic emissions. So, if we added anthropogenic emissions on top of that, the rise would be faster than anthropogenic emissions and we would clearly conclude that it’s not all anthropogenic.

  179. Pierre-Normand Houle says:

    ATTP wrote: “But I think your scenario is not physically plausible in the sense that if volcanoes suddenly started emitting 10GtC per year… ”

    You misread me. I said 10GtCO2 total. Both the super-volcano, and humans, release 10GtCO2. So the combined emissions are 20Gt. This could occur over a time span of several decades, if you like. You could also assume the the rates of emissions proceed in lockstep. We also are assuming that at the point where cumulative emissions have reached 20Gt, the atmospheric accumulation is a hair over 10Gt. The sinks are soaked up the rest, at whatever rate. What is your causal attribution for the 10.001Gt of atmospheric CO2 increase at that time?

    I am saying: 50% mankind and 50% nature.

    DM is committed to say: 100% anthropogenic
    (On the basis of the mass balance argument and his peculiar conception of causal attribution.)

    ATTP: ?

  180. I don’t know why your comment hit moderation. Two things: I think we all agree that how the natural sinks behave determines the rate at which atmospheric concentration rises. As far as your analogy goes, I think it depends on whether or not the enhanced volcanic outgassing could have caused a rise in the absence of anthropogenic emissions. Otherwise, all it is doing is changing the rate at which it is rising, not actually producing a rise of its own.

    However, this does feel a little as though it’s getting a bit pedantic, since I don’t think we disagree about what’s actually happening; we simply disagree about how to describe it. That’s just words 🙂

  181. dikranmarsupial says:

    “it is highly misleading to interpret the natural sinks as only mitigating the natural forcings just because they are both “natural”.”

    not that anybody is actually making that argument.

  182. dikranmarsupial says:

    “DM is committed to say: 100% anthropogenic”

    sorry that is just insulting, I am not committed to anything, I have a logical argument, the conclusion of which is that it is 100% anthropogenic.

  183. Pierre-Normand Houle says:

    ATTP: “As far as your analogy goes, I think it depends on whether or not the enhanced volcanic outgassing could have caused a rise in the absence of anthropogenic emissions. ”

    Of course if would have caused a rise. If the progressive injection of 20Gt has increased the atmospheric CO2 mass by 10Gt, then it is safe to assume that a progressive injection at half the rate (up to a 10Gt total injection) would have increased the atmospheric mass at least half as much. The sinks don’t care whether the CO2 is volcanic or anthropogenic. They respond to the atmospheric partial pressure of the well-mixed CO2.

    The relevant point is that the effect from humans emitting alone would have been the same as the effect from the super-volcano emitting alone. And in both cases, the increase would have been much smaller. But DM would insist that the cause of the atmospheric increase is 0% natural.

  184. The relevant point is that the effect from humans emitting alone would have been the same as the effect from the super-volcano emitting alone. And in both cases, the increase would have been much smaller. But DM would insist that the cause of the atmospheric increase is 0% natural.

    But then I’ll repeat that if both anthropogenic emissions and volcanic emissions would independently have caused a rise, then I do not think it is possible for the combined effect to produce a rise that is smaller than the anthropogenic emissions. In such a case, I think we’d all agree that the rise is a combination of anthropogenic and natural emissions.

  185. dikranmarsupial says:

    Tom, I completely agree that the mass balance analysis is subject to Duhem–Quine, just as any other theory regarding the real world. The auxiliary assumptions include the carbon cycle obeying the conservation of matter, which isn’t even entirely true (small amounts of 14C are created in the upper atmosphere by the action of cosmic rays), and the observations/estimates of the growth rate and anthropogenic emissions have plenty of auxiliary assumptions as well. However all theories and “laws” regarding the real world are subject to irreducible (if practically negligible) uncertainty, so it is to an extent taken as read that there we can’t establish anything with complete certainty outside maths (and sometimes not even then).

  186. dikranmarsupial says:

    ATTP wrote “In such a case, I think we’d all agree that the rise is a combination of anthropogenic and natural emissions.”

    Indeed, earlier in the discussion we discussed the attribution method that said the rise was 200% anthropgenic, 0.4% (or whatever) volcanic and about -100% natural overall. This correctly shows that volcanic activity does contribute to the rise, but shows that overall the natural contribution opposes the rise.

  187. dikranmarsupial says:

    “The relevant point is that the effect from humans emitting alone would have been the same as the effect from the super-volcano emitting alone. And in both cases, the increase would have been much smaller. But DM would insist that the cause of the atmospheric increase is 0% natural.”

    No, in that case the super-volcano would emit enough (i.e. as much as we would have) that the natural environment would no longer be a net sink, so I certainly wouldn’t say that.

  188. No, in that case the super-volcano would emit enough (i.e. as much as we would have) that the natural environment would no longer be a net sink

    Exactly.

  189. Pierre-Normand Houle says:

    dikranmarsupial wrote: “sorry that is just insulting, I am not committed to anything, I have a logical argument, the conclusion of which is that it is 100% anthropogenic.”

    Sorry, but no disrespect was intended in the least bit. It’s precisely *rational* commitment to the logical implications of your argument that I was ascribing to you. What I said was shorthand for “DM has an argument that has the consequence that … and hence he is rationally committed to endorse this conclusion unless he would acknowledge the argument’s validity or renounce one of the premises. This is better than simply saying “he believes that…” on your behalf.

    This is really a routine use of the word commitment (to mean “rational commitment”) in my academic circles, and has no nefarious psychological implications whatsoever. It’s meant to keep track of the dialectical situation.

  190. dikranmarsupial says:

    It is very poor short hand as it fails to mention the assumptions on which that committment is based, which implies there are none. Had you said “based on the mass balance analysis, DM would be committed to 100%” that wouldn’t have been insulting, merely incorrect (see above).

    However, it seems you have failed to keep track of the dialectical situation as your misrepresentations (see above) of my position suggest.

  191. Pierre-Normand Houle says:

    ATTP: “But then I’ll repeat that if both anthropogenic emissions and volcanic emissions would independently have caused a rise, then I do not think it is possible for the combined effect to produce a rise that is smaller than the anthropogenic emissions.”

    It’s not impossible at all. What you are saying has the implication that if the combined cumulative emissions are 20gT, then it is impossible that the oceans will have removed more than 10gT whatever the time frame of the emissions. But if it is possible, then, at that point in time, the mass balance argument will apply and DM will be rationally ‘committed’ (there is no better term really) to say that the natural contribution is 0% at that point.

  192. Pierre-Normand Houle says:

    Gt, not gT, of course.

  193. dikranmarsupial says:

    ” DM will be rationally ‘committed’ (there is no better term really)”

    O.K., so you are intentionally trying to wind me up. Sorry, that is just trolling.

  194. Pierre,
    Except, I think your example requires that nature is NOT initially in balance. So, again, I think that if nature is initially in balance and something natural (volcanoes) starts to release more CO2 than before, then nature becomes a net source, not a net sink.

  195. Maybe we should assume that this discussion has run its course. Two blogs, many days, there’s probably not much more than can be said. We don’t have to end up agreeing.

  196. dikranmarsupial says:

    ATTP indeed, I’m done, I did my best to reach an agreement with Pierre (note compromise terminology that Pierre briefly agreed to above), pity it was apparently a waste of my time.

  197. Pierre-Normand Houle says:

    DM wrote: “Indeed, earlier in the discussion we discussed the attribution method that said the rise was 200% anthropgenic, 0.4% (or whatever) volcanic and about -100% natural overall. This correctly shows that volcanic activity does contribute to the rise, but shows that overall the natural contribution opposes the rise.”

    What it shows is that the oceans (and other sinks) oppose the rise whatever the causes of the rise are. It opposes the effect from the human emissions just as much as it opposes the effect from the super-volcanic emissions. And it opposes then in exact proportion of their relative magnitudes. The the relative causal attribution to the sources of the rise (the abnormal emissions) ought not to be skewed by the fact that the oceans are “natural”. The sink response isn’t a negative “contribution” to the rise since it is entirely dependent on them. This is why it is similar to a feedback. It is not a causal contribution, but rather a natural *effect* that dampens *all* the real causes, natural and anthropogenic, without affecting their relative contributions.

  198. Pierre-Normand Houle says:

    ATTP “Except, I think your example requires that nature is NOT initially in balance. So, again, I think that if nature is initially in balance and something natural (volcanoes) starts to release more CO2 than before, then nature becomes a net source, not a net sink.”

    Yes, it’s true that in the beginning, when the airborne faction is still very large, the accumulation will be larger than the rate of human emissions alone. But at some time t1, the rate of ocean uptake will become larger than the the rate of human emissions alone. This will remain true until t2 when the cumulative emissions will have reached 20Gt and the total atmospheric increase will have reached 10Gt. So, considering the period from t1 to t2 when the volcanic and anthropogenic rates of emissions were equal, dikranmarsupial would still say that the causal attribution for the atmospheric increase was 0% natural during that period. Does that not strike you as something strange to infer from the mass balance argument alone?

  199. Pierre,

    Yes, it’s true that in the beginning, when the airborne faction is still very large, the accumulation will be larger than the rate of human emissions alone. But at some time t1, the rate of ocean uptake will become larger than the the rate of human emissions alone.

    Yes, this may be true. But that’s why I put the following in the post.

    There should have been a time when atmospheric CO2 rose faster than our emissions, and – similarly – there should have been a time when atmospheric CO2 would have continued rising were we to stop all our emissions. I don’t think either of these is true.

  200. Pierre-Normand Houle says:

    DM wrote: “O.K., so you are intentionally trying to wind me up. Sorry, that is just trolling.”

    Even after I’ve clarified my use and added the qualifier “rationally”? Is it really insulting that I would suggest to ATTP that you could be expected to endorse (be committed to) the logical consequences of your own argument, as you indeed did? I first used the word in a effort to be especially polite and not put words in you mouth. I wonder if ATTP discerned any pejorative connotation into it.

  201. I’m not sure we need to continue in this way. As I said above, I think this discussion has really run its course and is now heading into a territory that is best left alone.

  202. Pierre-Normand Houle says:

    ATTP: “There should have been a time when atmospheric CO2 rose faster than our emissions, and – similarly – there should have been a time when atmospheric CO2 would have continued rising were we to stop all our emissions. I don’t think either of these is true.”

    Yes. “Were we to stop” is a counterfactual conditional proposition. It’s not considered in the mass balance argument, which is a weakness. The mass balance argument, as applied by DM, would be applicable for the entire period between t1 and t2. Over that whole period, “nature” was “actively opposing” human emissions and hence the natural attribution of the increase is 0% natural according to this argument. It doesn’t test for the hypothetical effect of selective source removals, as it should for purpose of causal attribution.

    Tom Curtis had made an interesting mention of the Quine-Duhem thesis and its relevance to this problem. We are so used to relying on the tacit theories that inform our understanding of the carbon cycle, that we have some trouble countenancing the real (very weak) implications of the mass balance argument unaided by this tacit understanding (since it deals only with ‘raw data’ — net flux magnitudes) . When I propose thought experiments in order to show the insufficiency of the argument, you always are making assumptions that go ‘beyond the data’, as you indeed should, and are generally entitled to do, when studying real physical systems.

  203. When I propose thought experiments in order to show the insufficiency of the argument, you always are making assumptions that go ‘beyond the data’, as you indeed should, and are generally entitled to do, when studying real physical systems.

    Maybe I just assume some things are obvious.

    Yes. “Were we to stop” is a counterfactual conditional proposition.

    Why? If the mass balance argument indicates that nature is (and has been ever since we started emitting) a net sink, then that indicates concentrations would drop were we to stop emitting. I think this is an implicit result of the mass balance argument.

  204. > Nothing commits me to credit all the stable sources and sinks in the system as causal contributors in the attributions of a long term *change*.

    I have no idea why you suddenly speak of “stable” sources nor why you’d emphasize “change,” Pierre-Normand. What I know is that saying something like “50% mankind and 50% nature” commits you to omit all the sinks, which is far from being an accounting innovation.

    How you could pretend to a more refined concept of causation when it leads you to omit all the sinks is beyond me.

    As for the “credit all the stable sources,” it follows directly from your argument against Dikran’s. If you can appeal to a super-volcano to disrupt Dikran’s accounting, someone else can use counterfactuals to disrupt yours. Appeals to ignorance falter by reciprocation.

    Since we’re into Quinean territory, it can get even worse, as we could in principle appeal to the parts of a super-volcano, or we could switch to an event-based ontology where any of accounting entries get dissolved into an infinite chain of small sources and sinks. Think about it: what makes you think that a volcano causes anything?

    Hypothetical sources and sinks are infinite.

    ***

    > The thought experiment involving Professors X and Y shows that there exists logically consistent worlds in which the premises of the Mass Balance argument are true, and the conclusion false.

    Presenting a thought experiment that does not address the premises as stated above is of little help. Even if it did address the argument as stated by Dikran, the thought experiment could be parried by making one of the implicit premises Dikran assumed explicit.

    The possibility to patch one’s argument is what the Duhem-Quine thesis is all about for theories. The mass balance argument is more of an accounting model, but it does imply some theorical tidbits. If the only problem is Henry’s Law, add it to (5), right next to mass conservation. Again, I think (0) already parries everything:

    (0) What governs the rise in atmospheric CO2 is the difference between emissions and uptake; while there is a large exchange flux that is constantly swapping CO2 from the atmosphere with CO2 from the oceans and terrestrial biota, the exchange is a straight swap and has no effect whatsoever on atmospheric CO2 levels.

    https://andthentheresphysics.wordpress.com/2016/01/26/mass-balance/#comment-71562

  205. Pierre-Normand Houle says:

    ATTP: “Why? If the mass balance argument indicates that nature is (and has been ever since we started emitting) a net sink, then that indicates concentrations would drop were we to stop emitting. I think this is an implicit result of the mass balance argument.”

    Yes, of course. It is indeed an auxiliary assumption, based on generalization from past observations, that makes the argument scientifically valid. At Tom Curtis pointed out at SkS, when properly applied, this ‘mass balance argument’ becomes an inductive argument. It makes use of supplementary (albeit reasonable and scientifically justified) assumptions about the underlying causal structure of the carbon cycle. This is also what justifies expectations about what would occur in counterfactual scenarios. All this goes beyond what can be deduced (a deductive argument) based only on the premise that the rate of anthropogenic emissions is lager than the rate of increase in atmospheric CO2 concentration.

  206. > When I propose thought experiments in order to show the insufficiency of the argument […]

    What you call your thought experiments showed nothing of the sort, Pierre-Normand.

    “What if there was a super-volcano” is not a thought experiment: it’s an appeal to ignorance. Gerrymandering natural sources to try to put some of them on the positive side of the ledger is not a thought experiment: it amounted to the composition fallacy. Pushing for your own attribution question which implies that we can’t answer whether the raise in CO2 comes from natural variability or from anthropogenic outputs is not an argument: it’s a red herring.

    Ignoring these facts won’t make them go away, and trying to cling to Tom’s argument won’t help you.

  207. > It is indeed an auxiliary assumption […]

    AT was talking about an implicit result, Pierre-Normand. Consequences of the argument’s conclusion if you will.

    Assumptions are on the other side of the inference.

  208. Pierre-Normand Houle says:

    Willard,

    I earlier gave you credit for your excellent summary of Dikran’s argument, and he didn’t demur. However I can not endorse your paraphrases of my own argument. You are probably not reading me as carefully as you are capable of.

  209. Pierre-Normand Houle says:

    Willard wrote: “AT was talking about an implicit result, Pierre-Normand. Consequences of the argument’s conclusion if you will.”

    I assumed that he misspoke. Implicit assumptions are unspoken or non-explicit assumption. It makes sense to say that an argument relies on implicit assumptions. To say that an argument has a tacit result would mean that what one concludes from this argument is unspoken or non-explicit. I am unsure what that would mean, or why ATTP would have meant it that way. In any case, it seems like you are only picking nits.

  210. Pierre-Normand Houle says:

    Willard wrote: “AT was talking about an implicit result, Pierre-Normand. Consequences of the argument’s conclusion if you will.”

    To be fair, rather than writing “It is indeed an auxiliary assumption…”, I ought to have written “It is indeed a result from the argument that relies on further implicit assumption…” and that may have correctly captured his meaning. But it’s still quite a nit to pick.

  211. > when properly applied, this ‘mass balance argument’ becomes an inductive argument.

    Induction has three main uses: statistical reasoning, structural generalization, and case exhaustion. None of them are relevant to the mass balance argument

    Having to make some assumptions in your argument explicit may look inductive. However, it is not induction, or even abduction, but a deduction that pertains to informal logic. (We don’t say that Sherlock Holmes is making inductions to solve his investigations.) In our case, induction and abduction are related to how far you’re willing to go using the mass balance argument.

    As an argument regarding the balance question, it’s more deductive than anything. It’s an equational argument: it rests on an algebraic structure and is the result of an algebraic operator. If your accountant tells you that he uses inductive methods to manage your assets, fire him. (If your broker tells you that he uses deductive methods, fire him too.)

    As an argument regarding the attribution question, it’s abductive. The argument only tells us in which box to look first to find a main contributor. The more we try to find out how our CO2 overstock becomes warming, the less we can trust the mass balance argument.

  212. > I assumed that he misspoke.

    Here’s what AT said:

    If the mass balance argument indicates that nature is (and has been ever since we started emitting) a net sink, then that indicates concentrations would drop were we to stop emitting.

    In what way the “then” part should be included in the premises of the mass balance argument?

    ***

    > it’s still quite a nit to pick.

    Considering that you’re using the very same nit to bypass everything I said earlier, I’m not sure who’s exploiting that nit, Pierre-Normand.

  213. > I can not endorse your paraphrases of my own argument.

    Beware your wishes, Pierre-Normand.

    Making me work for you may be costly.

  214. Pierre-Normand Houle says:

    Willard wrote: “Induction has three main uses: stats, structural generalization, and case exhaustion. None of them are relevant to the mass balance argument”

    It’s inductive because it relies on assumptions that relate to our expectation about the way physical systems habitually behave, or would be expected to behave in counterfactual scenarios. Pretty much all scientific arguments are inductive except some inferences found in theory textbooks. Hume may not have been right to say that regularly conjoined occurrences in nature can’t be known to be causal (a skeptical position about causation), but he was right that the existence of causal relationships can’t be logically deduced on the basis of the observation of sequences of isolated events and the registering of mere correlations among them, however reliable.

  215. Pierre-Normand Houle says:

    Willard wrote: “Here’s what AT said:”

    He’s a big guy, so if he feels that I have failed to catch his drift, and the point has any relevance, I assume he will set me straight himself.

  216. > It’s inductive because it relies on assumptions that relate to our expectation about the way physical systems habitually behave, or would be expected to behave in counterfactual scenarios.

    Another semantical argument, this time with the buzzword of the moment: “assumption.” I can live with that.

    If you add all the relevant expectations regarding your system in the premises of your argument, it becomes deductive. Dikran did so by assuming that mass conserves. If you have other assumptions that would close the inference, add them and stop that one-upmanship about validity.

    ***

    > Pretty much all scientific arguments are inductive except some inferences found in theory textbooks.

    This is an accounting argument. Best of luck finding an inductive inference in an accounting textbook.

    ***

    > Hume may not have been right to say that regularly conjoined occurrences in nature can’t be known to be causal (a skeptical position about causation), but he was right that the existence of causal relationships can’t be logically deduced on the basis of the observation of sequences of isolated events and the registering of mere correlations among them, however reliable.

    The first part is untrue (hint: habit), and the second part has little to do with the mass balance argument, which is not about causal attribution, but causal detection.

    The mass balance argument simply tells us in which box to look to find the main source of the CO2 increase. It’s a simple stock problem. We’re not trying to find what exactly caused the increase, we’re trying to find where it comes from. That this kind of argument can’t be immuned to a counterfactual sleights of hand doesn’t imply it’s inductive: deductions outside formal systems closed under deduction aren’t immune either.

    Why we’re into induction claptraps for such a trivial problem is beyond me.

  217. dikranmarsupial says:

    “but he was right that the existence of causal relationships can’t be logically deduced on the basis of the observation of sequences of isolated events and the registering of mere correlations among them, however reliable.”

    That is inductive (observations -> rule), not deductive (working from axioms [premises] to derive new rules) reasonong. I agree with Willard that the first part:

    “Hume may not have been right to say that regularly conjoined occurrences in nature can’t be known to be causal (a skeptical position about causation),”

    is untrue, Hume was right to say that. We can gain additional confidence from empirical knowledge by its consistency with expectations from theory, but that doesn’t mean Hume was wrong about not being able to gain certain knowledge from any amount of empirical observation.

    I suspect that P.-N. has “deduction” and “induction” the wrong way round as deductive reasoning can involve assumptions about our expectations, they are called “premises”.

    However, this is much more Willard’s area than mine (my research being in humble inductive learning algorithms ;o)

  218. > He’s a big guy […]

    Is that a “routine” move in your “academic circles” when comes the time to read an explicit if-then clause, Pierre-Normand? AT washed his hands over this exchange at least twice already, so I’m not sure why you’d try to bring him back. I, on the other hand, am willing to follow through your concerns. While audits never end, if we go to the showdown now, we won’t have to replay the scene next time the mass balance argument comes up.

    Instead of deflecting toward AT, perhaps you should tell why we need to add a clause regarding the concentrations drop after we to stop emitting in the premises of the mass balance argument.

    I hereby declare my willingness to formulate your own arguments. If you could tell me if you’d prefer me to start with the appeal to ignorance or the composition fallacy, that’d be nice. Perhaps you’d like me to go backwards and start with your bogus concept of causation?

  219. > that doesn’t mean Hume was wrong about not being able to gain certain knowledge from any amount of empirical observation.

    Right, Dikran:

    Suppose a person, though endowed with the strongest faculties of reason and reflection, to be brought on a sudden into this world; he would, indeed, immediately observe a continual succession of objects, and one event following another; but he would not be able to discover anything farther. He would not, at first, by any reasoning, be able to reach the idea of cause and effect; since the particular powers, by which all natural operations are performed, never appear to the senses; nor is it reasonable to conclude, merely because one event, in one instance, precedes another, that therefore the one is the cause, the other the effect. Their conjunction may be arbitrary and casual. There may be no reason to infer the existence of one from the appearance of the other. And in a word, such a person, without more experience, could never employ his conjecture or reasoning concerning any matter of fact, or be assured of anything beyond what was immediately present to his memory and senses.

    Suppose, again, that he has acquired more experience, and has lived so long in the world as to have observed familiar objects or events to be constantly conjoined together; what is the consequence of this experience? He immediately infers the existence of one object from the appearance of the other. Yet he has not, by all his experience, acquired any idea or knowledge of the secret power by which the one object produces the other; nor is it by any process of reasoning, he is engaged to draw this inference. But still he finds himself determined to draw it: and though he should be convinced that his understanding has no part in the operation, he would nevertheless continue in the same course of thinking. There is some other principle which determines him to form such a conclusion.

    This principle is Custom or Habit. For wherever the repetition of any particular act or operation produces a propensity to renew the same act or operation, without being impelled by any reasoning or process of the understanding, we always say, that this propensity is the effect of Custom. By employing that word, we pretend not to have given the ultimate reason of such a propensity. We only point out a principle of human nature, which is universally acknowledged, and which is well known by its effects. Perhaps we can push our enquiries no farther, or pretend to give the cause of this cause; but must rest contented with it as the ultimate principle, which we can assign, of all our conclusions from experience. It is sufficient satisfaction, that we can go so far, without repining at the narrowness of our faculties because they will carry us no farther. And it is certain we here advance a very intelligible proposition at least, if not a true one, when we assert that, after the constant conjunction of two objects–heat and flame, for instance, weight and solidity– we are determined by custom alone to expect the one from the appearance of the other. This hypothesis seems even the only one which explains the difficulty, why we draw, from a thousand instances, an inference which we are not able to draw from one instance, that is, in no respect, different from them. Reason is incapable of any such variation. The conclusions which it draws from considering one circle are the same which it would form upon surveying all the circles in the universe. But no man, having seen only one body move after being impelled by another, could infer that every other body will move after a like impulse. All inferences from experience, therefore, are effects of custom, not of reasoning.

    http://www.18th.eserver.org/hume-enquiry.html

    My point was that we could say that Hume was skeptical about the “rational” nature of empirical knowledge. He did not dispute that we profit from empirical knowledge, only that it wasn’t based on any kind of deduction. By “reasoning,” Hume wasn’t talking about induction. He only used “induced,” and only four times in the text.

    The algorithms you study seem to have proved him wrong, at least insofar as machines are the extension of human nature. In any case, both the concepts of induction and deduction evolved since Hume’s times. Since then, Aristotle’s more natural conception of logic has been rediscovered. One does not simply call inductive any reasoning that does not pertain to sequents calculii.

    Formalizing is seldom useful if we can’t agree informally.

  220. Pierre-Normand Houle says:

    dikranmarsupial, you are objecting to my not endorsing Hume’s causal skepticism, with which you are seemingly broadly agreeing. But I think Willard was rather objecting to my characterization of Hume as a causal skeptic. He may be agreeing with Norman Kemp Smith who is one of the few scholars who argued that Hume was really a causal realist. I am myself uncommitted on this rather difficult exegetical question, because I haven’t delved into it at all. I had simply relied on the ‘consensus’ for the attribution to Hume.

    I’ll respond to the rest of your comment, and your seemingly good points, about inductive reasoning later on, provided only the comment section is still is open when I come back.

  221. dikranmarsupial says:

    “My point was that we could say is that Hume was skeptical about the “rational” nature of empirical knowledge. He did not dispute that we profit from empirical knowledge, only that it wasn’t based on any kind of deduction. ”

    I’ll have to think about that. My view (probably wrong-headed or outdated) was that we benefit from induction because it only needs to make skillful predictions, rather than being a source of reliable/certain knowledge, and that Hume was pointing out that induction cannot give us the sort of certainty that we can get from deduction.

    “One does not simply call inductive any reasoning that does not pertain to sequents calculii.”

    for some reason that made me think of Sean Bean as Boromir ;o)

    “Formalizing is seldom useful if we can’t agree informally.”

    indeed!

  222. > I think Willard was rather objecting to my characterization of Hume as a causal skeptic.

    I was objecting to the attribution to Hume that “regularly conjoined occurrences in nature can’t be known to be causal.” This would presume that knowledge can’t be custom-made. Reading the Enquiry suffices to show that he believed in causal knowledge. For instance, he speaks of the our knowledge of men’s “motives and inclinations” (where causation matters more than we may think) and of our “knowledge of cause.”

    His main point was to show that causation wasn’t the mere result of some reasoning processes. This served to undercut the whole rationalist (and perhaps also mechanistic) projects of his time. Popper should arguably be blamed for having transformed this into an enigma about induction. Perhaps it’s because of the D-N model apologists. (There’s a feedback loop here which would make Pierre-Normand refrain from speaking about causation; more on that later.) In any case, Hume has become the father figure of anti-inductivism.

    Online, I try to minimize the extent of my philosophical commitments. My ClimateBall ™ experience makes me see that reading is hard, so I try to focus on reading properly. Most of my points follow from what seems to me basic reading comprehension.

  223. stevenreincarnated says:

    You guys are thinking about this entirely too hard. Make the equation Ea – natural gas and En + natural gas. If you can prove something you know contributed didn’t by using your equation then it stands to reason you made a mistake. It is a shame this has gone on so long because DM makes some very good arguments about many things but this just isn’t one of them.

  224. steve,
    You’re going to have to explain that more, the equation is

    dC - Ea = En - Un.

    Left-hand side negative, right-hand side negative, nature a net sink. Simple. What is your natural gas?

  225. stevenreincarnated says:

    dC – (Ea – NG) = (En + NG) – Un

    So by using the mass balance equation and now combining NG (natural gas) in with natural sources you have proven it doesn’t contribute.

  226. So by using the mass balance equation and now combining NG (natural gas) in with natural sources you have proven it doesn’t contribute.

    What is natural gas? Ea is anthropogenic emissions, En is natural emissions, Un is natural uptake (there is no anthropogenic uptake). You seem to have simply added something new.

  227. stevenreincarnated says:

    Emissions from the anthropogenic combustion of natural gas. Sorry I guess I should have been more clear. I won’t be engaging here anymore though, so any further questions here will go unanswered.

  228. Emissions from the anthropogenic combustion of natural gas. Sorry I guess I should have been more clear.

    Well, then you haven’t put all the anthropogenic emissions on the LHS. You’ve put all anthropogenic emissions minus natural gas emissions on the LHS, and put natural emissions plus natural gas emissions on the RHS. How does that refute the argument that nature is a net sink? A crucial point of the mass balance argument is putting all the natural sources and sinks on one side of the equation.

    I won’t be engaging here anymore though, so any further questions here will go unanswered.

    Suit yourself.

  229. > dC – (Ea – NG) = (En + NG) – Un

    stevenreincarnated just redefined En and Ea by adding a subpart of each En and Ea as dummy variables.

    Not unlike double accounting.

    ***

    > If you can prove something you know contributed didn’t by using your equation then it stands to reason you made a mistake.

    If you freely introduce dummy variables that redefine the terms of an equation, it stands to reason that you’ve not refuted the original equation.

  230. TrueSceptic says:

    I’m quite puzzled by all this. Can someone explain why the following is wrong?

    ATTP writes

    dC – Ea = En – Un.
    The rise in atmospheric CO2 is smaller than our emissions, so the left-hand side is negative. Therefore, the right hand side is negative, nature is net sink, and therefore cannot be the source.

    I really don’t understand why we need to make things even this complicated. Surely all we need is
    Ea > dC
    (In fact, it’s very roughly Ea = 2*dC)
    For dC not to comprise some (roughly ½) of Ea, our CO2 emissions would need to be removed from the atmosphere by some unknown process as soon as they are produced (to avoid mixing) and at the same time an amount equivalent to roughly ½ of Ea would need to be emitted from natural sources. That is not impossible but surely so improbable it seems ludicrous.

    This must be too simple because we’ve have over 160 comments on the topic. What am I missing?

  231. > This must be too simple because we’ve have over 160 comments on the topic. What am I missing?

    ClimateBall ™.

  232. dikranmarsupial says:

    TrueSceptic, the thing the mass balance equation adds to this is it makes the assumption of conservation of mass explicit (i.e. it is an accounting exercise). FWIW the first IPCC WG1 report (somewhere about page 8 IIRC) just points out that the fact that the growth rate is less than anthropogenic emissions means that the rise isn’t a natural phenomenon. They didn’t bother with an equation (as it is a statement of the *%£# obvious) so you are essentially paraphrasing them.

  233. verytallguy says:

     What am I missing?

    Nothing.  They’re just enjoying a good argument. 

  234. > They’re just enjoying a good argument.

    That’s nothing compared to Bartemis’ daemon:

    The incredibly stupid so-called “mass-balance” argument rears its ugly head again.

    NS dynamically responds to atmospheric concentration. It is thereby a function of both NE and AE, NS = NS(NE,AE).

    We can observe that NE – NS(NE,AE) is less than zero, but that does not imply that nature on its own is a net sink. To establish that, you would have to demonstrate that NE – NS(NE,0) is less than zero.

    If you remove the human forcing, NS declines back to the level NS(NE,0) due to natural forcing alone. That means NS(NE,0) is less than NS(NE,AE). And, that means that just because NE – NS(NE,AE) is less than zero, it does not preclude NE – NS(NE,0) being greater than zero.

    This so-called “mass-balance” argument is the province of naive simpletons who have no experience with dynamic systems analysis.

    http://judithcurry.com/2015/05/06/quantifying-the-anthropogenic-contribution-to-atmospheric-co2/#comment-700621

    Pierre-Normand might allude to something like this with his three dots earlier.

    160 comments is a very conservative number, since Bartemis has 150 comments all by himself on that thread.

    And that’s just one recent thread at Judy’s.

  235. TrueSceptic says:

    Thanks for the responses. I can only say, KISS.

    I’m sure it said 166 responses last time I checked; I see it’s up to 236 now.

  236. TrueSceptic says:

    Oh, I’m talking about responses here, not at Judy’s. I rarely go there.

  237. verytallguy says:

    Willard,

    A rather prescient thread in which Judith convinced me she was absolutely beyond reasonable argument.

    Your pronouncements appear completely devoid of any rational thought or scientific process, but rather to support anything, however implausible, which provides any room to criticise the IPPC.

    Still seems current. 

    Also re arguments, and Mann

    I enjoy a good barney as much as the next man but I think we’ve enough on here without needing to go off topic to Mike.

    I expect Judith will post something suitably derogatory about him here soon and everyone will pile on, just like old times.

    Compare and contrast to actual content of her blog in the past week. 

    I think I shall change my moniker to nostradamus.

  238. Willard says:

    > It’s not even a particularly good argument.

    Agreed. Nevertheless, it shines as a test for algebraic reasoning.

    ***

    While I’m reading Judy’s thread, here’s a little something that shows how good ol’ skepticism may lead:

    Correct me if I’m wrong, but I believe that your argument is so strong that it undermines any kind of multi-causal analysis whatsoever. All you need is two variables and some plausible argument according to which these two variables may depend upon one another.

    We could even go further and use the argument to destroy any kind of analysis whatsoever. Pick a variable V. Consider the possibility that V may depend upon something beyond your epistemic boundaries. Put that something into non-V and your argument obtains: we have no idea if V is really V, and not non-V, say because it coheres dynamically with everything else that may exist.

    The alternative, of course, is to presume that identity works somewhat faithfully for humans, especially for our case scientists who do attribution studies. These scientists need to assume that the variables they identify could be designed in another way than they do. It just so happens that what they do just works.

    http://judithcurry.com/2015/05/06/quantifying-the-anthropogenic-contribution-to-atmospheric-co2/#comment-701277

    Since this hasn’t been cited here yet:

    If

    Δ – is the change in atmospheric CO2, over any period of a year or greater
    He – is the emission of CO2 due to humans burning fossil fuel,
    Ne – is the natural emissions of CO2 from all sources. Here, Eli is using the word nature to stand for everything except CO2 generated by burning fossil fuels.
    Na – is the total natural absorption of CO2,

    We can simply write

    Δ = He + Ne - Na

    This is an accounting identity. Rearrange the equation by subtracting He from both sides of the equation

    Δ - He = Ne - Na

    We know that emissions from humans burning fossil fuel He are greater that the change in atmospheric CO2 by about a factor of 2, so He > Δ and (Δ – He) is negative.

    0 > Δ - He = Ne - Na

    This means that Ne – Na must be negative, so the natural emissions must be less than the natural absorption or, Ne < Na, and nature is not the source of the observed increase in CO2 since the amount of CO2 emitted into the atmosphere by everything except burning fossil fuels is less than the amount of CO2 absorbed from the atmosphere by both physical and biological processes.

    See how easy it is. It is only necessary to know two things.

    First that the change in CO2 atmospheric concentration, Δ, is positive. That comes from the Mauna Loa observations, ice cores, you name it. Second that emissions due to burning of fossil fuel would increase the amount of CO2 in the atmosphere more than the observed increase (Δ-He < 0).

    That is known both from the source term, the amounts of fossil fuels mined (coal and tar sands), pumped (oil and gas) and a sink term, the amounts burned to generate electricity, run cars and trucks, etc. I f anything the measures of He are underestimates.

    http://rabett.blogspot.com/2015/05/2-3-0-or-why-natural-sources-and-sinks.html

  239. Willard says:

    Because, algebra, and because we miss a GRRROWTH interlude on this thread:

    > If I have an equation a – b = c – d and I know that a – b is negative, then I know for a fact that c – d is negative as well, even if I don’t know either of their actual values. This is just basic algebra.

    Indeed, which means the system is commutative, associative, distributive, identity follows equivalence, with inverses, etc. That you choose a distributive system shows you’re a socialist, BTW. Commutativity hints at communism, and associativity clearly shows you’re for unions. Don’t you see how the mass balance is just a way to kill the poor?

    Compare with Bartemis’ model. It’s dynamic. How can anyone be against dynamics? It’s life, it’s beauty, it’s love, it’s justice. More than that: it’s Grrrowth. Grrrowth is the only constant in the universe, and it’s a dynamic one.

    Thank you.

    http://judithcurry.com/2015/05/06/quantifying-the-anthropogenic-contribution-to-atmospheric-co2/#comment-702483

  240. Willard says:

    Guess who’s back:

    Pierre-Normand Houle | January 25, 2016 at 9:55 am |

    “The almost perfect correlation between the rate of atmospheric increase and our cumulative emissions and the lack of an explanation why nature would have contrived to cause the recent increase absent our emissions, is sufficient to justify the ascription of responsibility to our emissions.”

    It is far less than “perfect”. A much better relationship exists between temperature anomaly and the rate of change of CO2.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-761028

  241. Pierre-Normand Houle says:
  242. Michael Hauber says:

    Just to add some numbers to an example, and to eliminate the Co2 pulse.
    Assume:
    – percentage of Co2 in ocean at equilibrium is given by 90% + 1% per 0.1 degree of warming
    – solar warming of 0.1 degree per year
    – Initial Co2 of 10 tonnes in the air, and 90 tonnes in the ocean
    – man emits 2 tonnes/year
    – co2 exchange between air and ocean is fast enough to maintain equilibrium at all times.

    Then Co2 in the air will increase by 1.22 tonnes/year in this situation, and Co2 in the ocean will increase by 0.78 tonnes/ year. Man is adding 2 tonnes/year and there is a net flow of Co2 from atmosphere to ocean. However if man emits nothing then Co2 in air will increase by 1 tonne per year, so the natural factor dominates in this hypothetical examples

  243. Pierre-Normand Houle says:

    Michael Hauber’s new thought experiment is excellent. It indeed clearly illustrates that the *simple* mass balance argument is insufficient for purpose of causal attribution. Of course, he and I clearly agree that, when properly supplemented with evidence that we posses, in addition to the premise and conclusion of the mass balance argument, the argument that the recent atmospheric CO2 increase is very nearly 100% anthropogenic is conclusive. But we need to know more than just the fact that “nature” is removing more CO2 from the atmosphere than we are adding to it (the only premise of the mass balance argument) in order to validly infer this conclusion. We also need to know more about the behavior and/or history of the different sources and sinks (which we fortunately do).

    Michael Hauber beat me to the punch, but I’ll nevertheless provide a similar argument based on dikranmarsupial’s Smith/Jones analogy. This may prove more intuitive to people used to think about $’s rather than about CO2 flux variations.

    The original analogy, and XYZ-challenge, were posted by dikranmarsupial here:

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760276

    In this analogy, the Smith family deposits $100 every week in a business bank account shared with the Jones family. Ma and Pa Jones each make deposits or withdrawals of unknown amounts every week. The account balance increases regularly by $50 every weak. The ‘simple account balance argument’ enables us to conclude that the Jones family, as a whole, is removing $50 every week. The *invalid* inference, though, is that the Smith family is causally responsible for 100% (or more) of the increase of the bank balance. To see why, consider two simple scenarios regarding the separate contributions from Ma and Pa Jones.

    Scenario 1: Pa Jones isn’t depositing anything. At the end of the week, Ma Jones is always withdrawing 50% of whatever net amount everyone else has deposited during that week. This explains why the account balance is rising at a rate that is 50% of the weekly deposits ($100) of the Smith family. In that case, the Smith family is causally responsible for 100% of the $50 weekly rise. If they were to stop making deposits, the bank balance would immediately stop increasing.

    Scenario 2a: Pa Jones is depositing $900 every week. In this new scenario (2a and 2b), Ma Jones is always withdrawing 95% of whatever net amount everyone else has deposited during that week. Since the net weekly deposits (before her intervention) now are 1000$ , she is withdrawing $950. This explains why the account balance is increasing by $50 every week. In this case, dikranmarsupial would say that the Smith family still is causally responsible for 100% of the increase. I am rather saying that the Smith family is causally responsible for only 10% of the increase. Is this merely a disagreement over semantics? What would happen is the Smith family were to suddenly stop making their $100 weekly deposits?

    Scenario 2b: This is the continuation of scenario-2a. The Smith family suddenly stops making any deposits. The Jones family continues doing the same as they were doing… That is: Pa Jones still deposits $900 every week and Ma Jones still withdraws 95% from the total deposits. She therefore withdraws $855 per week. The account balance now rises by $45 every week.

    This, I would suggest, supports my claim that the Smiths (‘mankind’) were causally responsible for 10% of the weekly increase in scenario-2a. Not only were they contributing 10% of the total deposits, but as soon as they stopped contributing, the rate of increase of the account balance was reduced by 10%.

    This also would seem to answers dikranmarsupials XYZ challenge. It shows that, in scenario-2a, the Jones family (‘nature’) can be causally responsible for 90% of the rise in the bank account (‘atmospheric CO2’) even though they are removing more (because of Ma, ‘the oceans’) than they causally contribute (Pa, ‘the super-volcano’).

    I suspect that dikranmarsupial might resist this conclusion as regard the causal attribution to ‘nature’. He might thus dispute that I have adequately answered his XYZ challenge. But there are two conclusions that I think he must acknowledge:

    [1) The ‘simple account balance argument’, as used by the [Smith] family (who aren’t knowing the details of the Jones’ separate ‘source’ and ‘sink’ contributions),] applies just in the same way in scenarios 1 and 2a. It doesn’t enable one to infer what would happen if the Smith family were to stop contributing.

    2) It is not true that, because the Smith’s deposits are larger than the rate of the account balance increase, and because the Jones family is actively opposing the effect from their deposits on the account balance rise, that if the Smiths were to stop contributing, the account balance would begin to drop or, at least, stop rising.

  244. Brandon Gates says:

    It is far less than “perfect”. A much better relationship exists between temperature anomaly and the rate of change of CO2.

    Auuughhh, it stings! Why Dr. Curry, why? Inside of 2 years, farting unicorns will also explain the Stadium Wave. Takers?

  245. Willard says:

    > It indeed clearly illustrates that the *simple* mass balance argument is insufficient for purpose of causal attribution.

    This red herring conflates Pierre-Normand’s question and Dikran’s, yet again.

    ***

    > But we need to know more than just the fact that “nature” is removing more CO2 from the atmosphere than we are adding to it (the only premise of the mass balance argument) in order to validly infer this conclusion.

    An argument that has only one premise is at best circular. The formulation above has at least six. We can add more if needed.

    ***

    > The *invalid* inference, though, is that the Smith family is causally responsible for 100% (or more) of the increase of the bank balance.

    That’s not what Dikran says:

    [T]he mass balance argument establishes that the natural environment is a net carbon sink. For me this i[s] sufficient to conclude that the natural environment as a whole is opposing the rise rather than causing it. Nowhere here have I said anything different, as I have only been considering the natural carbon cycle as a whole, because has I have repeatedly pointed out, cherry picking a natural source is a zero-sum game. The part of the rise due to the cherry picked source is exactly cancelled by a corresponding increase in the net sink formed by the remainder of the natural carbon cycle. So at the end of the day, it is only the net natural response that is relevant.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760324

    That’s the second time now that I’m quoting this to Pierre-Normand.

    So yet again Pierre-Normand transforms the mass balance argument as an attribution question, and yet again misrepresents Dikran’s position. In response to this strawman, Dikran observed (January 26, 2016 at 3:27 am) that Pierre-Normand simply rediscovers that “nature includes sources as well as sinks,” a fact which we already know and that the balance argument already takes into account.

    Here’s another interesting corrolary:

    Now the mass balance analysis also shows that the net natural sink has been growing over time, so if some natural source (say Ev) has been strengthening with time, it means that some other natural source has been weakening (or sinks strengthening) by an even greater amount. Again picking out volcanoes tells you nothing.

    He also observed that “the carbon cycle does not respond to increases in individual sources and sinks, it essentially responds to the atmospheric concentration.” Perhaps adding that in the premises of the mass balance argument would parry the composition fallacy that follows in Pierre-Normand’s conclusions.

    ***

    > I am rather saying that the Smith family is causally responsible for only 10% of the increase. Is this merely a disagreement over semantics? What would happen is the Smith family were to suddenly stop making their $100 weekly deposits?

    The argument is not only semantics, but mostly. It’s also RHETORICS ™. In this case, there are at least two tricks. The first is to transform Dikran’s question (to which the 10% does not provide a response) by omitting the debits of the accounts. The second is to conflate the notion of credit and profit.

    The balance argument only tells us where to find the profit. To claim that the Smith family is causally responsible for 10% of the profits stretches the notion of [financial] responsibility of the Jones family beyond credulity.

    ***

    There’s seldom the need to end a thought experiment with a rhetorical question, more so when Dikran already answered:

    Yes, because the natural environment is still a net sink.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760450

  246. Oale says:

    I just wanted to have the last word on whatever that was about. 😛

  247. Pierre-Normand Houle says:

    Willard,

    I am making two claims about the simple mass balance argument.

    The main premise used by advocates of this argument is that atmospheric CO2 concentration is (and had been for a while) rising at a significantly lower rate than our emissions. This is sufficient to establish that nature as a whole is a net sink and that it is actively opposing our emissions. I agree with this.

    My two further claims about the simple argument are that, on the basis of this premise:

    1) It doesn’t establish that the rise is 100% anthropogenic.

    2) It doesn’t establish (under realistic scenarios) that if we were to stop entirely our emissions overnight the atmospheric CO2 concentration would begin to drop rather than merely continue to rise at a lower rate.

    You are suggesting that those two claims are directed at straw men opponents, and that dikranmarsupial never denied them. This tends to suggest that you yourself are agreeing with them. Aren’t you?

  248. Dear Pierre-Normand,

    It’s been what? More than three days that you vaguely paid attention to what I said. And now you’re asking me to work for you? Again?

    Besides, how come neither your (1) nor your (2) refers to causation or responsibility? What’s up with this “the rise is 100% anthropogenic”? Don’t you see the equivocation with the word “rise” in (1)? Don’t you see how you transform a stock problem into a flow problem with your (2)? Do you realize at least that when you do transform stocks into flows you need to accept that attribution can go beyond 100% quite easily?

    Why don’t you take the argument numbered above and work with it instead of trying to portray it as a single premised argument, or now as an argument with a major? Do you really think repeating over and over again the same thought experiments will clarify anything if you can’t even keep up with an argument that purports to be explicit? Why don’t you acknowledge the many times Dikran answered these? What’s up with repeating over and over again that the balance argument is invalid when the many rebuttals have been met by crickets?

    Do you understand how annoying it is to argue by questions?

    Why don’t you scratch your own itch and find your quote yourself?

    At the very least, do you agree that a credit ain’t always a profit?

    ***

    As promised earlier, here’s your appeal to ignorance:

    Some *part* of nature (if not volcanoes, then maybe something else) can cause (part) of the increase, just as much as we can. In order to rule out volcanoes, or any other part of nature, you have to go beyond the ‘mass balance argument’.

    Once you accept that kind of possibility, no balance argument can ever follow. Accounting can’t be immuned from a “something else” it hasn’t taken into account. Appealing to ignorance can dissolve any knowledge claim whatsoever.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760366

    Don’t you realize that I could take your argument and destroy any balance argument whatsoever, and in fact any kind of argument based on mere observations of behaviors?

    Once you give a skeptic a white box that remains black to you [1], I can almost guarantee that you’ll lose. I’m not sure yet about the winning strategy, but a good first move seems to be to redefine the box elements. Just like you did.

    [1]: https://rjlipton.wordpress.com/2014/02/08/black-versus-white-boxes/

  249. Pierre-Normand Houle says:

    Willard,

    I asked you two simple questions and you chose not to commit yourself. That’s because you believe they involve some sort of confusion, or my misunderstanding dikranmarsupial’s position. Fair enough.

    I indeed acknowledged in my recent post that “I suspect that dikranmarsupial might resist this conclusion [e.g. dispute my meaning of “X% natural”, where X > 0] as regard the causal attribution to ‘nature’. He might thus dispute that I have adequately answered his XYZ challenge.”

    That’s because, indeed, my understanding of the meaning of “100% anthropogenic” (and, correspondingly, of “0% natural”) differs from his since he and I have diverging intuitions regarding conceivable policy relevant causal attributions of changes in atmospheric CO2 concentration.

    Which is also why I asked you the second question about the implications of the simple mass balance argument on the expected consequences of a sudden interruption of our emissions. Would the atmospheric concentration necessarily drop, if we had formerly been emitting at more than 100% of the rate of the rise, or could the atmospheric concentration possibly continue to increase, only at a somewhat reduced rate? Both dikranmarsupial and ATTP seem to have thought that if we are emitting at a significantly higher rate than rate of uptake by nature, then it would drop in any realistic scenario (e.g. with the same laws of nature, no E.T. interventions, etc.) My thought experiment, as well as Michael Hauber’s, demonstrate that this intuition is wrong. It doesn’t follow from the simple mass balance argument at all. And this has relevant implications for the understanding of causal attributions.

  250. My thought experiment, as well as Michael Hauber’s, demonstrate that this intuition is wrong. It doesn’t follow from the simple mass balance argument at all.

    I think the word “simple” is important here. Any mass balance argument that also assumes some knowledge of the actual system does work. Also, Michael’s thought experiment seemed to be the wrong way around (did he means 90% – 1% per 0.1 degree of warming?). It’s clear that in his example there would be a period when it would rise in the absence of our emissions and, if we continued indefinitely, a period in which the rise would exceed our emissions.

  251. dikranmarsupial says:

    Pierre-Normand “I indeed acknowledged in my recent post that “I suspect that dikranmarsupial might resist this conclusion ”

    Do me a favour, leave my name out of the discussion of the mass balance argument and just discuss the argument on its own terms, especially if you are going to mention me in a way that implies that I am being obstinate (again!). As Willard pointed out, you have been consistently misrepresenting my position, which suggests you are in no position to assume you know my response to particular questions. I

  252. Pierre-Normand Houle says:

    dikranmarsupial, my post was an analysis of the argument on its own terms followed by queries about your possibly agreeing or disputing my conclusions. I merely acknowledged that the first conclusion that I drew (regarding causal attributions) might not seem successfully argued to you owing to our diverging intuitions about the point and meaning of causal attributions. I fail to see how any of that constitutes some misrepresentation. Did I ascribe any view to you that isn’t yours? Maybe, unwittingly, in the past. Where in that post in particular? I think it’s a bit unfortunate that Willard drove by and poisoned the well.

  253. dikranmarsupial says:

    Pierre-Normand read Willard comment, and read it carefully and you will see how you are misrepresenting my position. It is ironic that you criticise Willard as he can see the distinction that you continually miss. It is a pity that you ultimately chose to reject the compromise I suggested that resolves the contradiction in your argument (the natural environment is opposing the rise, even though it contains elements that contribute to it).

    “Did I ascribe any view to you that isn’t yours? Maybe, unwittingly, in the past. ”

    No, you did so today a couple of times, e.g. here, but I stopped trying to discuss this with you after it became clear that you were not listening, and I have no duty to actively correct your misrepresentations, and it is unreasonable for you to expect me to do so.

  254. Pierre-Normand Houle says:

    ATTP “I think the word “simple” is important here. Any mass balance argument that also assumes some knowledge of the actual system does work.”

    That very much has been my position from the beginning. Also had put this caveat again in my post: “Of course, he and I clearly agree that, when properly supplemented with evidence that we posses[s], in addition to the premise and conclusion of the mass balance argument, the argument that the recent atmospheric CO2 increase is very nearly 100% anthropogenic is conclusive.”

    *Simple* means that we only know that our emissions are significantly larger than natures rate of uptake. What can be inferred from that, under plausible scenarios?

    Does is not surprise you that atmospheric concentration could continue to rise at a 10% lower rate after we discontinue our emissions, despite the fact that nature was already removing 50% our emissions, and this in a realistic scenario and in a world with physical laws just like our own? This seems to be unlike many of the thought experiments proposed so far.

    I hadn’t seen Michael Hauber’s mistake. I had only noticed the similarity with my own. I am going to look more closely at his thought experiment.

  255. Pierre-Normand Houle says:

    dikranmarupial, It would greatly help me correctly interpret your position if you would tell me if, yes or no, you agree with the last conclusions that I drew from my thought experiment. In fact, you don’t even have to bother with the thought experiment at all. The conclusion is that:

    The mass balance argument doesn’t rule out that atmospheric concentration could continue to rise at a 10% lower rate after we discontinue our emissions, despite the fact that nature was already removing 50% our emissions, and this in a realistic scenario and in a world with physical laws just like our own.

  256. dikranmarsupial says:

    Pierre-Normand, sorry, as I pointed out I have stopped trying to discuss this with you because you are clearly not listening, so there is no point in me continuing to answer your questions. Please do continue to discuss this if you want, but please leave me out of it, and stop attributing views to me that I do not hold.

  257. Pierre-Normand Houle says:

    dikranmarsupial,

    Well, I was going to post an apology because I was feeling rather guilty for ascribing to both ATTP and yourself (even with the cautious qualifier “seem to have thought”) the view that CO2 concentration would necessarily drop after we cease all our emissions at a time when nature is a net sink “actively opposing” them. ATTP had expressed this view a few times in this thread, in the context of exchanges where you had seemed to be agreeing while arguing against my position, and discounting my examples because of this. And it had seemed to me that this intuition was also driving some of your arguments on the previous thread. But I couldn’t find an unambiguous supporting quote. Then I remembered having read your SkS post on the mass balance when this discussion began. So I looked back. If this is a misrepresentation, as you now allege, then that means you must have changed your mind. Of course, you are entitled to change your mind.

    “You say I that I believe all sources and sinks are accounted for. That is not correct, and the mass balance argument does not depend on knowledge of the sources and sinks, I have said that repeatedly, so you ought to know that by now. The mass balance argument is a means of inferring the difference between total natural emissions and total natural sources. That is all you need to know to be sure that nature is a net sink and hence CO2 levels would be falling if not for our emissions.” — Dikran Marsupial

    https://www.skepticalscience.com/argument.php?p=1&t=97&&a=125

  258. dikranmarsupial says:

    Pierre-Normand I am dissapointed that you chose not to honour my request to be left out of your continuing participation in this thread. I want to continue reading it, as other contributors may make interesting comments, e.g. Tom’s comments are always well worth reading, but I don’t want to continue discussing this with someone that isn’t listening (the fact that you ignored my request is further evidence of this).

    However to indulge you, The mass balance argument establishes that “nature is a net sink”, the corollary that “CO2 levels would be falling if not for our emissions” is also based on a further assumption that there was no radical change in the behaviour of the natural carbon cycle. That assumption was indeed unstated, however I would have thought the “all things being otherwise equal” was fairly obvious. However whether the rise was (note past tense) was natural or anthropogenic depends not on what nature might have done, or what it may do in the future, but what it actually did do. The mass balance analsysis shows that the natural environment did oppose the rise. I haven’t changed my mind, it is just that you are reading more into my earlier comment than is actually there.

  259. I do think we should drop people who ask to be left out. I’m not a fan of the rather standard blogosphere technique of insisting others answer their question.

    To clarify the position with respect to CO2 levels dropping. If we were to halt all emissions, they would indeed start dropping. That’s because the system does not (unlike Michael’s analogy) equilibrate instantly. I’m not, however, quite sure why this has come up, though.

  260. Pierre-Normand Houle says:

    To whom it may concern,

    It has been suggested that the mass balance argument has the consequence that, if nature is currently a net sink, then, if we were to completely stop our emissions, the atmospheric concentration would begin to drop. The reason for this seems to be that nature has been opposing the rise and would be expected to continue to remove atmospheric CO2 after we stop our emissions. And this would only be inferred, however, on the assumption that there was no radical change in the behavior of the carbon cycle during the period of attribution.

    This suggestion seems problematic. That’s because if the mass balance argument is supposed to have any relevance to *attribution* (i.e. to determining whether the rise is anthropogenic, natural, or a little bit of both), then, it ought not to have built into it the assumption that there *wasn’t* any natural contribution to the rise. So, the phrase “radical change in the behavior of the carbon cycle” can’t possibly refer to just any conceivable natural cause of the CO2 rise. But what would be a conceivable natural cause of (part of) the rise that *wasn’t* a “radical change in the behavior of the carbon cycle”, just in the way our own emissions have been during the period of attribution?

    If, however, what is meant to be excluded just is a radical change coincidentally occurring at the time when we would stop our emissions, then this exception clause would be perfectly reasonable. But then, the simple counterexample that I offered in my thought experiment would stand, since no radical change in the behavior of the carbon cycle occurs at the time when the anthropogenic emissions (i.e. The Smiths’ deposits) stop. Yet, in that case, the atmospheric CO2 (i.e. the bank balance) keeps rising at a slightly reduced rate.

  261. Pierre,
    Except now we’re talking about scenarios that we largely know are non-physical. If the system equilibrates instantly after each emission pulse, then it would be possible for concentrations to continue rising if we were to halt all emissions. However, this is not true in reality (or, at least, we think it’s not true) and the reason it would drop if we were to completely halt all our emissions is that the decay – or adjustment – time for each emission pulse is ~ 100 years.

    You might argue that we can’t know this from the mass balance argument alone. However, I’m not sure that’s true. If you consider Gavin Cawley’s paper, you can get the residence and adjustment times from the fluxes, and so I think that a basic mass balance calculation can tell you if the concentration would drop, or not, were we to completely halt all our emissions.

  262. To add to the above, I think the basic way to explain the constant airborne fraction is that our emissions are rising exponentially and the decay time for each pulse is also exponential (see Nick Stokes’s post). If this were not the case (if the equilibrating were instant) then I don’t think you would get a constant airborne fraction. Hence, I don’t think you need to know details about the system to infer things from a basic mass balance calculation alone.

  263. dikranmarsupial says:

    P.-N. obviously I should not have indulged your poor behaviour as I did in my last comment. Discussing that answer to your question “no radical change in the behavior of the carbon cycle” is not leaving me out of the discussion, and saying “To whom it may concern,” doesn’t change that (and frankly comes across as just a taunt). Even then you misrepresent, yet again, what was actually said.

  264. Pierre-Normand Houle says:

    ATTP: “To clarify the position with respect to CO2 levels dropping. If we were to halt all emissions, they would indeed start dropping. That’s because the system does not (unlike Michael’s analogy) equilibrate instantly. I’m not, however, quite sure why this has come up, though.”

    It has come up just because I provided a simple counterexample that refutes it. (I typed a few paragraphs right now and deleted them because my argument was too abstract and liable to confuse). You really ought to refer to my Smith/Jones thought experiment that is readily interpreted into a simple and realistic humans/super-volcano/oceans scenario. I stripped it to the bare-bones and it expresses to the core of my issue regarding the mass balance argument and causal attribution. (And thanks for fixing the post).

    It’s just four short paragraphs beginning with: “In this analogy, the Smith family…”

    https://andthentheresphysics.wordpress.com/2016/01/26/mass-balance/#comment-71873

  265. Pierre,
    Yes, but – again – I think your example is one in which the system equilibrates instantly. I don’t have time to work through this in detail right now, but I think a simple extension of the mass balance calculation (as done, for example, in Gavin Cawley’s paper) would indicate that – in the case of the real carbon cycle – it does not equilibrate instantly and, in fact, has an adjustment time of ~ 100 years. Hence (unless I’m mistaken) I think one can rule out instant equilibration using basic mass balance.

    So it might be true for your analogy, but I don’t think we need to add more complexity to the basic mass balance calculation to show that it wouldn’t be true for the case of the carbon cycle.

  266. Nathan Ditum says:

    Tom Curtis’ example above of why the mass-balance fails as it ignores Henry’s law seems correct to me and is explained in more detail on this blog that I found while researching the so-called Revelle Factor: http://chipstero7.blogspot.co.uk The post also explains issues with the ice-core, the isotopic measurements, the Revelle Factor, inter alia.

  267. Nathan,
    Well, those of us who were making the mass balance argument were assuming that Henry’s Law was given. So, one can certainly construct a fake world in which it fails, but not a real one.

    Technically, I guess one can argue that if one also includes knowledge of Henry’s Law then it’s no longer simply a mass-balance argument. That may be true, but it’s possible that given all the mass balance info (i.e., all the fluxes over time) that one can rule out a natural component anyway (as in Gavin Cawley’s paper) but I need to think about this a little more.

  268. Nathan,
    I’ll have to look at your Revelle factor post in more detail, but I think it’s wrong. The Revelle factor is not (I think) required to show that the adjustment time for a pulse of CO2 is quite long (~ 100 years) – see Gavin Cawley’s paper above. The Revelle factor – as I understand it – limits how much of a pulse of excess CO2 can ultimately be absorbed by the oceans, not the timescale over which the adjustment happens. That post is confusing the residence time for a single molecule, with the adjustment time for a pulse of CO2. They’re not the same.

  269. dikranmarsupial says:

    Nathan, I haven’t had time to read the document properly, but I think there may be issues to do with the adjustment time residence time confusion. The residence time between the surface ocean and the deep ocean is a bit misleading as it only tells you about the rate of exchange between the surface ocean and the deep ocean, but the rate at which carbon is transferred from the surface ocean to the deep ocean is much slower as it depends on the net flux between the surface and deep ocean, rather than on the magnitude of the flux from the surface to the deep ocean.

    Essentially residence times tell you almost nothing about the rates of increase and decrease in the masses of the reservoirs comprising the carbon cycle because it mostly represents the rates of exchanges (i.e. swapping CO2, which doesn’t change the mass of the reservoirs involved), wheres the adjustment times describe the rates at which the masses of the reservoirs change (as they are governed by the net flux, which is a transfer rather than an exchange of carbon).

  270. dikranmarsupial says:

    Nathan, your description of the mass balance analysis is incorrect, [the blog states] “This would be how much CO2 is assumed we are contributing to the CO2 greenhouse annually and the argument would be correct if we knew precisely how much CO2 all the sources and sinks were emitting/absorbing but it seems unlikely that we possess this precise level of knowledge”

    The mass balance argument does not require any knowledge of natural emissions or uptake, as clearly stated by the paper you cite:

    “It should be noted that a common objection to arguments relating to the anthropogenic effect on the carbon cycle is based on the fact that the best available estimates of the individual fluxes, shown in Figure 1 [i.e. natural source and sink fluxes], are highly uncertain, such that the error bars on Fi and Fe are typically larger than the volume of anthropogenic emissions. However, this objection does not apply to the mass balance arguments, as the net environmental flux, Fi − Fe, is not calculated from uncertain estimates of Fi and Fe, but from the difference between dC/dt
    [atmospheric growth rate] and Fa [anthropogenic emissions], both of which are known with far greater certainty”

  271. > I asked you two simple questions and you chose not to commit yourself. That’s because you believe they involve some sort of confusion […]

    Thank you for reading my mind.

    Why don’t you scratch your own itch and find your quote yourself?

    At the very least, do you agree that a credit ain’t always a profit?

  272. I think that article even has the wrong definition for the Revelle factor. It says

    The Revelle Factor sets a fixed equilibrium partitioning ratio for CO2 in the atmosphere and surface-ocean of 10:1. This means that if we increased CO2 by 10ppmv the surface-ocean would absorb 1ppmv (or 10%) upon equilibrium.

    The Revelle factor

    is the ratio of instantaneous change in Carbon Dioxide (CO2) to the change in total dissolved inorganic carbon (DIC)

    I’ll probably get this wrong, but Eli can come along and tell me off if I do 🙂

    The relevant point is that the Revelle factor is about 10, which is essentially saying that

    \dfrac{\Delta CO_2}{CO_2} = 10 \dfrac{\Delta DIC}{DIC},

    where CO2 here is the aqueous CO2 in the surface ocean, and DIC is the total dissolved inorganic carbon. The atmospheric CO2 is essentially linearly dependent on the aqueous CO2 in the surface ocean (there’s a temperature dependence that we can ignore for now).

    For reasons I can’t fully explain (mainly because I did this months ago and have forgotten some of it) our emissions have increased DIC from around 2000 micro-mol/kg, to around 2050 micro-mol/kg. That means that 10 \Delta DIC/DIC is about 0.25. Therefore \Delta CO_2/CO_2 = 0.25 and the stable CO2 concentration will have increased by 25%. If we consider the pre-industrial levels were 280ppm, if we stopped emitting, it would drop, but would not drop below 280 + 0.25 x 280 = 340ppm – or, rather, dropping below 340ppm would take a long time because it would be done through the slow carbon cycle.

    Okay, I haven’t worked this out before, so I hope it right. But I think that this is one reason why we essentially expect about 20%, or more, of our emissions to remain in the atmosphere for a very long. Anyone who understands this better than me is welcome to correct me if I’ve blundered in some way. I have been meaning to do this for a while, so you can regard this as an attempt to start 🙂

  273. > I’m not a fan of the rather standard blogosphere technique of insisting others answer their question.

    If these otters insist in playing Socrates, I don’t see why not:

    Source: http://discourseontheotter.tumblr.com/post/126939860670/alex-juhasz

  274. Nathan Ditum says:

    “The mass balance argument does not require any knowledge of natural emissions or uptake, as clearly stated by the paper you cite”

    Yes it does. Because the equation they are applying to determine the size of the (human) contribution to the atmosphere’s content of greenhouse gases disregards Henry’s law and also disregards the fact that there are many sources and sinks. This apparently simple matter is surprisingly complicated in fact. It entails estimating not only the total natural emissions of greenhouse gases but also the total natural absorption of the same gases and the rates at which they are being absorbed by the earth’s various sinks, plus consideration of their respective residence-times in the atmosphere, land and oceans too. None of these things are known with very much certainty at the present time and therefore it is not yet possible to do the calculations that could settle the question of how big a contribution to the atmospheric greenhouse global humanity is making or has made in the past. It is possible that anthropogenic CO2 emissions are absorbed locally (as suggested by Tom Quirk) while natural emissions are originating elsewhere.

    There is also Henry’s law to consider as Tom Curtis points out above, which further complicates the matter. For example, say we had a can of soda-pop with an average temperature of 15C and added 100 grams of CO2 into the headspace above the water. The CO2 would rapidly equilibrate with the water until 98 grams has been dissolved in water and 2 grams resided in the headspace in accordance with the 1:50 partitioning ratio at that temperature. Now imagine at the same time we increased the water-temperature by 5C and thereupon shifted the partitioning ratio to 1:40. Instead of 0.98 grams being dissolved into the water 97.5 grams would be dissolved, leaving 2.5 grams in the headspace. At the same time, some CO2 would be outgassed from the water due to the temperature-change, let’s assume 10 grams. The end result is that the water has simultaneously absorbed 97.5% (almost all) of the CO2 we added while increasing the CO2 in the headspace due to the temperature-change. This is one of only many reasons as to why the mass-balance argument (as it is being applied) is invalid.

    “I think that article even has the wrong definition for the Revelle factor”

    The article does not “define” the Revelle Factor that way. It simply says that for every 10 ppm of CO2 we add to the atmosphere around 1 ppm will be absorbed by the surface ocean upon equilibrium. (Of course the oceans are absorbing more than 10% because CO2 is diffusing to the deep ocean which essentially frees-up space). As Revelle himself says: “A 10% increase of the CO2 content of the atmosphere need merely be balanced by an increase of only 1% of the total CO2 content in seawater in order to reach a new equilibrium”. The Revelle Factor increases as the concentration of CO2 in the surface ocean increases in accordance with the Siegenthaler equation in the article. And the Revelle Factor we are told apparently arises because of the way CO2 is partitioned between CO32 and HCO3 in the surface ocean.

    “That post is confusing the residence time for a single molecule, with the adjustment time for a pulse of CO2. They’re not the same”

    No. The post is not doing anything of the sort. The post is not using residence time to argue against the idea of a long adjustment time. The post is using Henry’s law, the growth-rates from Salby, and Tom Quirk’s analysis to argue against the long adjustment time.

  275. Nathan Ditum says:

    Of course that should read: Instead of 98 grams being dissolved into the water 97.5 grams would be dissolved, leaving 2.5 grams in the headspace.

  276. verytallguy says:

    Nathan

    it is not yet possible to do the calculations that could settle the question of how big a contribution to the atmospheric greenhouse global humanity is making or has made in the past.  

    Yes, it really is.  It’s all of it.  By inspection.

  277. dikranmarsupial says:

    Sorry Nathan, conservation of mass requires that

    dC = Ea + En – Un

    where dC is the change in atmospheric CO2, Ea is total anthropogenic emissions, En is total natural emissions (from all sources, known or unknown) and Un is total natural uptake (by all natural sinks, whatever the mechanism). Rearranging

    En – Un = dC – Ea

    We know both of the things on the right with good certainty, so we know the thing on the left with at least equal certainty. So we know that the natural environment is a net sink, without needing to know the numerical value of En or Un, or the physical processes giving rise to them.

  278. Nathan,
    I didn’t realise that the article was written by you.

    This alone shows that it is nonsense,

    This following post puts forward the argument that the assumed increase in atmospheric CO2 of 120ppmv since 1850 is not the result of human CO2 emissions.

    As much as I’d love to spend a great deal of my time engaging in a discussion with someone who appears to think that the increase in atmospheric CO2 is not the result of human emissions, it is Friday afternoon, I’d like a nice relaxing weekend, and it’s never turned out well before. Feel free to continue promoting and believing this, but ideally not here.

    the growth-rates from Salby

    Well, there’s one of your problems straight away.

  279. Nathan Ditum says:

    “As much as I’d love to spend a great deal of my time engaging in a discussion with someone who appears to think that the increase in atmospheric CO2 is not the result of human emissions, it is Friday afternoon, I’d like a nice relaxing weekend, and it’s never turned out well before. Feel free to continue promoting and believing this, but ideally not here”

    That’s fine. Your forum your rules.

  280. dikranmarsupial says:

    Prof. Salby’s mathematical error explained here, Humlum’s in the peer reviewed comments following his in the journal.

  281. Marco says:

    Nathan
    “A 10% increase of the CO2 content of the atmosphere need merely be balanced by an increase of only 1% of the total CO2 content in seawater in order to reach a new equilibrium”

    and

    “for every 10 ppm of CO2 we add to the atmosphere around 1 ppm will be absorbed by the surface ocean upon equilibrium”

    are not equivalent.

  282. Marco says:

    “the growth-rates from Salby” – if I read it correctly, you actually looked at the acceleration of the growth rate, but claimed a 300% increase in growth rate.

  283. Nathan,
    Apologies if my response sounded rude, but suggesting that the rise in atmospheric CO2 is not anthropogenic is just bizarre. If you follow some of the links at the begining of this post, you’ll see that there are many lines of evidence indicating that it is anthropogenic.

  284. Marco,
    Not that I want to expand this discussion too far, I think Nathan’s error is the assumption that the Revelle factor only applies to the surface ocean, which I believe is incorrect.

    If I understand it correctly, doubling atmospheric CO2 would increase DIC by about 10%. Total DIC is something like 30000 GtC, so the increase would be about 3000 GtC. Doubling atmospheric CO2 would mean increasing atmospheric CO2 by 590GtC. So, the total increase is 3590 GtC, of which 590/3590 ~ 17% is in the atmosphere. This – I think – is why we expect about 20% (or more if we were to emit even more) of what we emit to remain in the atmosphere for a very long time (thousands of years).

  285. Phil says:

    Nathan,

    Your soda-pop analogy does not correspond to the real world, where the partial pressure of CO2 in the atmosphere is continually increasing due to anthropogenic emissions. As ppCO2 increases, more CO2 is absorbed in the ocean. This essentially sets up a counter flow to that suggested by Henry’s law. The relative magnitude of the two phenomena determines whether the oceans act at net sink or source.
    If your analogy applied to the real world, then oceans would be becoming less acidic (as CO2 degasses) – observations show the oceans becoming more acidic.

  286. > Because the equation they are applying to determine the size of the (human) contribution to the atmosphere’s content of greenhouse gases disregards Henry’s law and also disregards the fact that there are many sources and sinks.

    The first part is either implied by (0) above or can be added to (5) without any inconvenience for the argument. The last part is false.

    ***

    > It [this apparently simple matter] entails estimating not only the total natural emissions of greenhouse gases but also the total natural absorption of the same gases and the rates at which they are being absorbed by the earth’s various sinks, plus consideration of their respective residence-times in the atmosphere, land and oceans too.

    That long sentence is incomplete, as it lacks an (indirect) object. The presumed object is a red herring: to repeat for the nth time, the mass balance argument does not seek to replace a full-blown attribution study. There’s no need for such study to establish that nature’s a net sink, which means the CO2 profit comes from the human box.

    ***

    The idea that we need to look into the specific properties of each elements of the two boxes is the second trick PNH tried a few days ago at Judy’s:

    I’m going to tell you a little secret: you’re exploiting the composition fallacy. It fails, because the fact that the whole of the natural carbon cycle is net negative doesn’t imply the same for all the processes within it. DM has never made that inference, and it’s all yours.

    In accounting, what you’re trying to sell can get you in jail. Ma wouldn’t be proud: she never wanted her sons to be accountants.

    http://judithcurry.com/2016/01/24/undersea-volcanoes-may-be-impacting-long-term-climate-change/#comment-760422

    I repeat this quote to fulfill the second part of my promise made earlier. The Ma in question was Ma Dalton, because PNH used Joe in his analogy:

    https://en.wikipedia.org/wiki/Ma_Dalton_(Lucky_Luke)

    If the properties of each sources and sinks were relevant for the mass balance equation, then one of the premises of the argument would need to fall. One does not simply refute an accounting problem by refusing to play by double ledger accounting rules.

    The third part involves doing some more accounting.

  287. dikranmarsupial says:

    bit too verbose perhaps for Mr Bean.

  288. Pierre-Normand Houle says:

    Willard wrote: “… to repeat for the nth time, the mass balance argument does not seek to replace a full-blown attribution study. There’s no need for such study to establish that nature’s a net sink, which means the CO2 profit comes from the human box.”

    Agreed with the first sentence, not the second.

    The simple mass balance argument, by itself, only establishes that, over any given time period, (1) all the sources of profit taken together — e.g. the ‘human volcano’, as R. Gates used to call it, plus any other natural contributor to the rise there might be — are larger than nature’s gross sink (i.e. the oceans’ and biosphere’s reactive increase in uptake), and *also* that (2) the human contribution alone is larger than the (atmospheric) profit. It fails, however, to entail that no part of nature also could be a source of profit, or even, possibly, a larger source of profit than us. The fact that the reactive sink response increased fast enough to cancel *more* than our own separate contribution to the increase is consistent with it also canceling more that some equally large natural contribution to the increase(*).

    So, the conclusion of the simple mass balance argument ought only the be that our contribution to the CO2 profit is of a larger magnitude than the profit. It doesn’t establish our contribution as “the” place where the profit comes from. Establishing more than that does require “full-blown attribution” — that is, going beyond the simple mass balance argument(**). That’s my only point.

    (*) I count as natural “contribution to the increase” only variations, or disruptions, of the carbon cycle that would partially account for the rise after some period of stability. The ‘human volcano’ (i.e. anthropogenic emissions) is such a disruption of the carbon cycle, as would be, for instance a super-volcano.

    (**) One only has to look at the very high correlation between cumulative anthropogenic emissions and the increase in atmospheric CO2, for instance, and/or discount other potential sources on the basis of oxygen depletion rates, carbon isotopes, etc. This is all part of attribution (fingerprinting).

  289. oale says:

    Attempting to get the last word again… I betcha -5 € you guys haven’t even started to talk about the compensation we’d need to pay for the early farmers descendants for their work against an ice age back in -4004 AD (the start of anthropocene). I’d say, they’ve pretty excellently kept the sea levels stable too, thus increasing the value of the coastal properties, so it would be owners of these who should be the primary compensators.

  290. snarkrates says:

    Pierre-Normand Houle, Why rule out supernatural explanations? I mean GODDIDIT works so well for the creationists. It can explain anything–literally.
    Here’s a clue, Punkin. If you are saying that anthropogenic emissions are not the culprit, you have to posit another specific cause as the explanation. Testable hypotheses. That’s how science works.

  291. Pierre-Normand Houle says:

    snarkrates: wrote: “If you are saying that anthropogenic emissions are not the culprit,…”

    I am not saying that at all. I am convinced that the CO2 increase in the atmosphere is very nearly 100% anthropogenic. I’ve said it many times in this thread. I’ve just argued that the ‘simple mass balance argument’ isn’t sufficient on its own to infer this. But the argument advanced by ATTP in the OP *is* sufficient. Read my first post in this thread where I staked my position.

    https://andthentheresphysics.wordpress.com/2016/01/26/mass-balance/#comment-71578

  292. oale says:

    Ah, still it goes on. Here’s the thing. I’m not remotely interested on what you say. The mass balance equation can be split massively just like all equations. The mankind is a net emitter. The nature has still been a net sink if we check this thing yearly. That may change in the future. That change may be large. Or will be large if it is large. I admit this probably isn’t the last word on this subject, but it tries to be. Still I’m not going to read what was discussed in this thread in the last 250 comments because I just want the last word. Hopefully ATTP keeps this thread open, though it’s not been intersting after someone added the potentially applicable term in the equation in the beginning of this thread. This could indeed be in use, if the mankind in some point of foreseeable future, and we cannot predict human behavior that well, at least yet, becomes a net sink, which is pretty difficult as we breathe. And possibly continue to breathe if there are enough plants using sunlight. There’s no use in responding, I won’t read it.

  293. Pierre-Normand Houle says:

    ATTP wrote: “Yes, but – again – I think your example is one in which the system equilibrates instantly. I don’t have time to work through this in detail right now, but I think a simple extension of the mass balance calculation (as done, for example, in Gavin Cawley’s paper) would indicate that – in the case of the real carbon cycle – it does not equilibrate instantly and, in fact, has an adjustment time of ~ 100 years. Hence (unless I’m mistaken) I think one can rule out instant equilibration using basic mass balance.

    So it might be true for your analogy, but I don’t think we need to add more complexity to the basic mass balance calculation to show that it wouldn’t be true for the case of the carbon cycle.”

    Yes, that’s a good point. In my analogy the system equilibrates instantly because Ma Jones ( = the oceans’ sink response) adjusts her contribution to the size of the total independent deposits (= the combined emissions of mankind and the super-volcano) rather than to the current bank balance. So, this introduces a disanalogy with the mankind/super-volcano/ocean scenario that my model purports to represent. But this is quite easily fixed. Ma Jones only has to make the size of her withdrawals proportional to the current bank account balance, and her full adjustment to any change in deposit rates will occur progressively. Further modifications would be required to model subsequent adjustments of the airborne fraction, but I don’t think this wouldn’t undermine the point of the analogy.

    It’s true that, in the case where the sink response adjustment is progressive, when the Smith family (=mankind) immediately discontinues its deposits, the bank balance will immediately begin to drop. That was your main point, I think. That’s because, indeed, the ‘bank-borne fraction’ (= airborne fraction) of their deposits is twice the previous rate of increase of the bank balance. (This is the gist of the simple mass balance argument). But this consideration falls far short from demonstrating that the Smith family was causally responsible for the increase. That’s because if Pa Jones (= the super-volcano) were to interrupt his deposits, the effect on the bank balance would also be to cause it initially to drop, and, what is more, would cause it to drop 9 times faster.

    Remember also that I am not suggesting that a scenario like that has any likelihood of being actual in our world, or couldn’t very easily be discounted. I am only arguing that it isn’t discounted merely on the basis of the consideration that nature is a net sink. In the counterfactual scenario that I proposed, the super-volcano causally contributes 9 times more to the rise than mankind does, and yet “nature” ([i]including[/i] the super-volcano contribution) still is a net sink.

  294. Pierre-Normand Houle says:

    In my previous message, still caught in moderation, I wrote:
    “That’s because, indeed, the ‘bank-borne fraction’ (= airborne fraction) of their deposits is twice the previous rate of increase of the bank balance.”
    I meant to say:
    “That’s because, indeed, the ‘bank-borne fraction’ (= airborne fraction) of their deposits is half the size of their deposits.”

  295. Pierre-Normand Houle says:

    Another error, though not very consequential: PNH: “That’s because if Pa Jones (= the super-volcano) were to interrupt his deposits, the effect on the bank balance would also be to cause it initially to drop, and, what is more, would cause it [initially] to drop [17] times faster.”

  296. oale says:

    Apparently, there are people who like to talk to plants. I’m told, it helps the plants grow. By this line of thought, we might construct a hypothesis, that endless chatter on radiowaves might generate a field which helps plants grow better. I though have not seen any evidence of this kind of radiofield induced promotion of growth. Further, we might pray for a god growth. This is supposed to be heard by God and if God’s willing, he may transmit our wishes to the plants. This is all pretty interesting and might make for a case of human induced growth of plants, but still, I think the people talking to plants aren’t telling them to photosynthetize, but rather encouraging them to keep well and such. And of course we can’t command God to do our bid, we may just ask. Of course there are many gods, so how can we know if say f.e. praying to Shiva would be the correct course of action to raise some beetroots? This all may matter in our mass balance calculations, but I’d rather stick to the science, see the article, it’s pretty simple.

  297. snarkrates says:

    Pierre-Normand Houle,
    What I am saying is that in the context of science, mass balance + the lack of any other credible putative cause for the increase is sufficient.

  298. Pierre-Normand Houle says:

    snarkrates said : “What I am saying is that in the context of science, mass balance + the lack of any other credible putative cause for the increase is sufficient.”

    For sure. I never said that it was insufficient *when* there aren’t any credible alternatives. There indeed aren’t any credible alternative to human emissions as a cause for the recent increase (over the last 150 years or so). But *if* there has been some such alternative (e.g. if the past history had been a little different and there had been a significant natural source causally contributing to the increase), the ‘simple mass balance argument’ could easily have been falsified.

    I think people tend to confuse current arguments that relie only *in part* on mass balance considerations — such as arguments that also rely on the very strong correlation between our cumulative emissions and atmospheric CO2, and/or on isotope fingerprinting of source, etc. — with a quite specific deductive argument that is, on its own, invalid. This is what I have attempted to explain, and demonstrate, in this thread. There only seems to have been two or three people who got it. I never for a second questioned the current state of the science regarding the carbon cycle and the unique rôle of our emissions in causing the recent increase. This has never been about questioning established science, but rather about improving understanding.

  299. Nathan Ditum says:

    “If I understand it correctly, doubling atmospheric CO2 would increase DIC by about 10%. Total DIC is something like 40000 GtC, so the increase would be about 4000 GtC. Doubling atmospheric CO2 would mean increasing atmospheric CO2 by 560GtC. So, the total increase is 3590 GtC, of which 590/3590 ~ 17% is in the atmosphere. This – I think – is why we expect about 20% (or more if we were to emit even more) of what we emit to remain in the atmosphere for a very long time (thousands of years).”

    What you’re saying here is certainly interesting and I this what I initially assumed too. I thought that the Revelle Factor applied to the whole oceans. However take note there is no time-variable in the Revelle Factor formula (ΔPCO2ml/PCO2ml)/(ΔDIC/DIC) and the total amount of CO2 water can absorb based on that formula remains eternally constant over time until the relative concentrations of DIC change. Hence if the deep-ocean had the same DIC ratio as the surface-ocean the total amount of anthropogenic CO2 the whole ocean would absorb at equilibrium would only be 10%. The sources I have seen (such as from Sabine) imply that the Revelle Factor is only applicable to the surface-ocean. As Wikipedia says “The Revelle factor (Buffer factor) is the ratio of instantaneous change in CO2 to the change in total dissolved inorganic carbon (DIC), and is a measure of the resistance to atmospheric CO2 being absorbed by the ocean surface layer. The buffer factor is used to examine the distribution of CO2 between the atmosphere and the ocean, and measures the amount of CO2 that can be dissolved in the mixed surface layer”. If I saw something definitive that the Revelle Factor applied to the whole oceans I would change by blog-post. The reason, as I understand, is that it applies to the surface-ocean only because the DIC ratio in the surface-ocean (which is affected by biota) is not the same as in the deep-oceans.

  300. Nathan,
    I’m trying to work this out myself, but as I understand it, this buffering applies everywhere where the CO2 will be in the form of dissolved inorganic carbon. So, as you transfer CO2 deeper into the oceans, the same basic process applies. Until the CO2 is removed via the slow carbon cycle, I think Revelle factor limits how much of our CO2 can be absorbed by the oceans. The current position is that something like 20% of our emissions will remain in the atmosphere for millenia. You should read some of David Archer’s papers.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s