Natural vs human generated CO2 – the Salby slides

Last year the climate scientist Murry Salby gave a rivetting presentation to the Sydney Institure to describe the natural processes that dominate the CO2 concentration in the atmosphere. A devastating blow to the climate alarmists if the thesis stands up. At the time the full list of slides could not be reproduced but they can all be seen in this presentation, hot off the press from the Institute.

Possibly the main points are (1) the dynamic relationship between the sources and sinks of CO2, with the big source (and sink) being the oceans, (2) the very small human contribution to atmospheric CO2, in the order of 4% and (3) the role of temperature that LEADS rather than following changes in atmospheric CO2.

RIP warming alarmism?

Daniel Hannan, the sensible member of the European Parliament on tour town under discussed the state of the war between the warmists and the sceptics. Faced with the suggestion that the realists have ”in effect won the Battle of Midway”  and now we are just “mopping up”  he was inclined to agree. In Europe they simply can’t afford to waste any more money. Maybe we can:)

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10 Responses to Natural vs human generated CO2 – the Salby slides

  1. AndrewL

    Given that the very small (4%) human contribution is bigger than the actual net increase I don’t see how his argument that the increase is due to natural emissions stands up. All he is pointing out is that the ability to absorb the increase in human emissions varies from year to year.

    He also has to answer what has driven temperature increase if CO2 doesn’t. If he is only pointing out that CO2 emissions and absorption changes with temperature, he is only pointing out a feedback.

    I don’t know which temperature proxy he used but it stopped before 2000 and was unreferenced. Why didn’t he show CO2 ice core proxies going back to the Medieval Warm Period? Surely the proxies should show a similar increase in CO2 at that period to today, if his thesis is correct.

  2. Biota

    He also has to answer what has driven temperature increase if CO2 doesn’t.

    Which warming was that Andrew? The warming that started well before any detectable anthropogenic CO2 contribution? Or the warming that has ceased for the last ten years while anthropogenic CO2 has been steadily increasing?

  3. AndrewL

    Biota, that would be the warming Salby said he didn’t want to get into the reason for with this audience.

    By climate cycles, you mean Milankovitch Cycles, Rafe?

  4. cohenite

    Given that the very small (4%) human contribution is bigger than the actual net increase I don’t see how his argument that the increase is due to natural emissions stands up.

    Whether humanity is responsible for all the increase in CO2 in the 20thC is one of the most vexed issues of the AGW debate; it is given a good thrashing here.

    Andrewl’s argument that because human CO2, ACO2, increase exceeds the increase in CO2 then ACO2 must be the cause of the increase in CO2 is flawed for a number of reasons.

    Firstly it ignores the fact that natural increases in CO2 have occurred in the past and did not rely on ACO2 because there was none.

    Secondly Knorr’s paper shows that the % of ACO2 in the atmosphere has stayed the same despite increases in ACO2 and CO2 so ACO2 cannot be responsible for the entire increase in CO2 levels.

    This can be demonstrated quite easily, the principle is a constant in an increasing total: say ACO2 is 20% of CO2 which is 100, so ACO2 is 20; when CO2 is 200 ACO2′s 20% will be 40 so other CO2 has contributed 60; at 300, ACO2 is 60, other is 140 and so on; natural CO2 must be contributing to the increase in total CO2.

  5. AndrewL

    The atmosphere and biosphere don’t care where the carbon comes from. As Salby points out the CO2 is homogenized in the atmosphere. A simple mass balance tells you that if you can reduce the amount of anthropogenic carbon dioxide entering the atmosphere you will either reduce the rate of carbon dioxide build up regardless of natural sources.

    It is entirely possible natural emissions are increasing as a feedback to increased temperature. It is only Salby’s denial of basic physics that the double bond of the carbon dioxide molecule absorbs and then re-radiates thermal energy that allows him to be sanguine about his research.

    Knorr’s paper is not definitive and there are other papers showing a small increase ( which in fact Knorr’s does when the influence of ENSO and volcanic activity, things Salby points to that affect the carbon cycle) in the anthropogenic carbon air fraction. Knorr’s conclusion is that further research is required to answer this question.

  6. cohenite

    The atmosphere and biosphere don’t care where the carbon comes from

    No, only alarmists do.

    A simple mass balance tells you that if you can reduce the amount of anthropogenic carbon dioxide entering the atmosphere you will either reduce the rate of carbon dioxide build up regardless of natural sources.

    This is a strawman; noone is denying ACO2 contributes to the total mass of CO2 in the atmosphere. What a fucking stupid thing to say! What sceptics are saying is that ACO2 does not cause ALL the increase in CO2; in fact the amount of increase ACO2 causes is small.

    This is shown by 2 official “mass balance” calculations. The first is by the IPCC, the second is by the US Department of Energy. The relevant part of the DOE report is page 22, Table 3.

    In respect of an individual ACO2 molecule the residency time can be calculated simply thus: the ACO2 contribution [in Figure 7.3]is 8Gt out of 218.2 Gt CO2 flux or 3.67%; DOE stats give an even lower figure of 2.91% of the emitted CO2 from the surface; DOE shows that about 98.5% of total emitted CO2 is reabsorbed so the proportion of ACO2 after one year is 3.67/100 x 1.5/100 = 0.000552 so that one ACO2 has a 1 in 1811.594203 chance of still being there after one year; the chance after 2 years is 1 in 120772.9469. Effectively one ACO2 molecule will be gone in 2 years.

    Before you answer that the atmosphere does not selectively reabsorb ACO2 molecules but ALL CO2 molecules and therefore my calculations are wrong consider what Alan McIntyre writes:

    atmospheric change [of CO2] = human emissions [ACO2] + natural sources – natural sinks

    That gives:

    atmospheric change – human emissions = natural sources – natural sinks

    Changing that into an algebraic equation where A = increase, B= natural sources, C= human sources, we get

    A = B + C -(1)
    and C > A -(2)

    Then rearranging (1) and substituting (2) we get:

    A – B > A which rearranges to B < 0. -(3)

    Now, let's call A the increase in atmospheric CO2, B is the net amount
    added from natural sources and C is the man-made component. We don't
    know what B is, but we know the values for A and C fairly accurately,
    and we know that C is greater than A – in fact about twice as large.

    Then equation (3) tells us that B < 0, meaning that natural sources
    are
    negative – in other words a net sink. "

    For the period prior to human existence, which is 99.9+% of earth's
    history, C= 0, so if A < B, the amount of CO2 has been decreasing
    lately, highly unlikely with a supposedly warming climate.

    A less simplistic equation would be A = B+C – P(B+C) where P is a fraction removed from the atmosphere/ocean system over the course of a year, due to fish excreting calcium carbonates, shellfish dieing and not having their shells recycled immediately into the biosphere, etc.

    http://www.sciencedaily.com/releases/2009/01/090115164607.htm

    For a numerical example, let B = 100, C= 5, and P = 99/100.

    Then A = 100 + 5 – (99/100)*(105) = 105- 103,95= 1.05.
    Since human activity produces 5, your equation erroneously assumes that without humans there would be a carbon sink since 5-1.05 = 3.95.

    Remove human CO2 from the equation and you get
    A = 100 + 0 – (99/100)*(100) = 100 – 99, or an increase of 1 rather than 1.05

    That is, ACO2 contributes about 5% of the CO2 increase; pretty close to the 3.97 of the CO2 flux which the IPCC, figure 7.3 shows.

  7. AndrewL

    This is a strawman; noone is denying ACO2 contributes to the total mass of CO2 in the atmosphere. What a fucking stupid thing to say! What sceptics are saying is that ACO2 does not cause ALL the increase in CO2; in fact the amount of increase ACO2 causes is small.

    You might want to check Murray Salby’s talk, Cohenite.

    the role of temperature that LEADS rather than following changes in atmospheric CO2.

    Salby’s point is that temperature is driving the CO2 increase, not human emissions. He claims short and long term atmospheric carbon dioxide increase is independent of human emissions. The flaw in his argument is that while his model may hold for the present conditions, when hindcast for ice ages with 4-5 degree drops in temperature he would require a negative CO2 level.

    Conservation of mass says that what we dig up and emit, or what is emitted from clearing land must end up either in the ocean, air or land in the short term. What papers like Knorr’s show is that 40-55% of our emissions end up in the air, nature’s carbon sinks have increased to absorb greater emissions. I am surprised that would come to the conclusion that we are responsible for only 5% of increase if you have cited Knorr. It simply disproves your assertion, your error is assuming that natural sinks are constant. They are driven by concentration, and hence absorb more with greater concentration, moderating the increase in CO2 in the atmosphere.

    If this isn’t the case you have to resort to Salby’s model to explain why CO2 increase has coincided with human emissions. If you do that it is hard to explain why all life doesn’t die out in ice ages.

  8. Hi Andrew,
    Salby doesn’t have a “model”. All he discusses is observational data. The bottom line is that CO2 increases do not coincide with human emissions. At times human emissions are going down while CO2 levels are still increasing, and vice versa. What the CO2 levels do correlate with much better are large El Nino’s.

    And no it does not follow that you would have a “negative” CO2 level during an ice age. Cold temps increase absorption by water so the ocean absorbs more Co2, and hence there is less in the atmosphere. Of course there are other factors like reduced vegetation during an ice age (so both less decay and less absorption by plants as well). During an ice age Co2 levels decay down to a background level.

    Personally I think Salby’s work is the death knell of the entire AGW theory.

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