For a another view on the CO2 issue, please see also the guest post by Tom Vonk: CO2 heats the atmosphere…a counter view -Anthony
Guest Post by Ferdinand Engelbeen
There have been hundreds of reactions to the previous post by Willis Eschenbach as he is convinced that humans are the cause of the past 150 years increase of CO2 in the atmosphere. For the (C)AGW theory, that is one of the cornerstones. If that fails, the whole theory fails.
This may be the main reason that many skeptics don’t like the idea that humans are the cause of the increase and try to demolish the connection between human emissions and the measured increase in the atmosphere with all means, some more scientific than others.
After several years of discussion on different discussion lists, skeptic and warmist alike, I have made a comprehensive web page where all arguments are put together: indeed near the full increase of CO2 in the atmosphere is caused by the human emissions. Only a small part might have been added by the (ocean) warming since the LIA. That doesn’t mean that the increase has a tremendous effect on the warming of the earth’s surface, as that is a completely different discussion. But of course, if the CO2 increase was mainly/completely natural, the discussion of the “A” in AGW wouldn’t be necessary. But it isn’t natural, as the mass balance proves beyond doubt and all other observations agree with. And all alternative explanations fail one or more observations. In the next parts I will touch other items like the process characteristics, the 13C and 14C/12C ratio, etc. Finally, I will touch some misconceptions about decay time of extra CO2, ice cores, historical CO2 measurements and stomata data.
The mass balance:
As the laws of conservation of mass rules: no carbon can be destroyed or generated. As there are no processes in the atmosphere which convert CO2 to something else, the law also holds for CO2, as long as it stays in the atmosphere. This means that the mass balance should be obeyed for all situations. In this case, the increase/decrease of the CO2 level in the atmosphere after a year (which only shows the end result of all exchanges, including the seasonal exchanges) must be:
dCO2(atm) = CO2(in1 + in2 + in3 +…) + CO2(em) – CO2(out1 + out2 + out3 +…)
The difference in the atmosphere after a year is the sum of all inflows, no matter how large they are, or how they changed over the years, plus the human emissions, minus the sum of all outflows, no matter how large they are, wherever they take place. Some rough indication of the flows involved is here in Figure 1 from NASA:
From all those flows very few are known to any accuracy. What is known with reasonable accuracy are the emissions, which are based on inventories of fossil fuel use by the finance departments (taxes!) of different countries and the very accurate measurements of the increase of CO2 in the atmosphere on a lot of places on earth, including Mauna Loa.
Thus in the above CO2 mass balance, we can replace some of the items with the real amounts (CO2 amounts expressed in gigaton carbon):
4 GtC = CO2(in1 + in2 + in3 +…) + 8 GtC – CO2(out1 + out2 + out3 +…)
Or rearranged:
CO2(in1 + in2 + in3 +…) – CO2(out1 + out2 + out3 +…) = – 4 GtC
Without any knowledge of any natural flow in or out of the atmosphere or changes in such flows, we know that the sum of all natural outflows is 4 GtC larger than the sum of all natural inflows. In other words, the net increase of the atmospheric CO2 content caused by all natural CO2 ins and outs together is negative. There is no net natural contribution to the observed increase, nature as a whole acts as a sink for CO2. Of course, a lot of CO2 is exchanged over the seasons, but at the end of the year, that doesn’t add anything to the total CO2 mass in the atmosphere. That only adds to the exchange rate of individual molecules: some 20% per year of all CO2 in the atmosphere is refreshed by the seasonal exchanges between atmosphere and oceans/vegetation. That can be seen in the above scheme: about 210 GtC CO2 is exchanged, but not all of that reaches the bulk of the atmosphere. Best guess (based on 13C/12C and oxygen exchanges) is that some 60 GtC is exchanged back and forth over the seasons between the atmosphere and vegetation and some 90 GtC is exchanged between the atmosphere and the oceans. These flows are countercurrent: warmer oceans release more CO2 in summer, while vegetation has its largest uptake in summer. In the NH, vegetation wins (more land), in the SH there is hardly any seasonal influence (more ocean). There is more influence near ground than at altitude and there is a NH-SH lag (which points to a NH source). See figure 2:
The net result of all these exchanges is some 4 GtC sink rate of the natural flows, which is variable: the variability of the natural sink capacity is mostly related to (ocean) temperature changes, but that has little influence on the trend itself, as most of the variability averages out over the years. Only a more permanent temperature increase/decrease should show a more permanent change in CO2 level. The Vostok ice core record shows that a temperature change of about 1°C gives a change in CO2 level of about 8 ppmv over very long term. That indicates an about 8 ppmv increase for the warming since the LIA, less than 10% of the observed increase.
As one can see in Fig. 3 below, there is a variability of +/- 1 ppmv (2 GtC) around the trend over the past 50 years, while the trend itself is about 55% of the emissions, currently around 2 ppmv (4 GtC) per year (land use changes not included, as these are far more uncertain, in that case the trend is about 45% of the emissions + land use changes).
We could end the whole discussion here, as humans have added about twice the amount of CO2 to the atmosphere as the observed increase over the past 150 years, the difference is absorbed by the oceans and/or vegetation. That is sufficient proof for the human origin of the increase, but there is more that points to the human cause… as will be shown in the following parts.
Please note that the RULES FOR THE DISCUSSION OF ATTRIBUTION OF THE CO2 RISE still apply!
Paul Dennis says:
August 9, 2010 at 9:40 am
“Paul, I couldn’t disagree with you more. Any interpretation of the empirical data has to satisfy the observations.”
It is not sufficient that it satisfy the observations. It must not assume its conclusions.
Arthur Rörsch says:
August 10, 2010 at 3:08 am
“The full balance equation reads:
dFin + Fem – dFout = Fa
With figures:
12.89 + 7 – 16.39 =3.5
Thus the contribution of the assumed natural additional source dFin = 12.89 against de Fem= 7, is contributing to the flux into the atmosphere of 3.5.”
Dikran Marsupial says: 9 aug. 2.30
“Surely dFin is more than cancelled by dFout, and so the net contribution of the natural environment is still negative. dFin isn’t contributing to the rise if dFout is taking back even more.”
Some simple calculations. All the fluxes are the same gas
Total IN = 12.89+7 =19.89
Fraction Fem=7/19.89=0.35
OUT and Fa will have the same composition.
Thus the Fa consists for 35 % of the anthropogenic emission = 1.225 GtC/y
Fa consists for 65 % of the other source dFin = 2.275 GtC/y (That is not a negative contribution. It is a substantial one)”
No, that is faulty reasoning. Consider the example of a married couple with a joint bank account. The husband (representing anthropogenic influences) deposits 8 Euro and withdraws nothing; his wife (representing all natural influences) deposits 12 Euros, but withdraws 16 Euros. The couples bank balance (represnting atmopsheric CO2) has risen by 4 Euros (12 + 8 – 16 = 4).
Would it be sensible to conclude that the husband were responsible for 8/(12+8) = 0.4 of the rise and his wife 12/(12+8) = 0.6 of the rise? No of course not, common sense is enough to tell you that the husband was solely responsible fot the increase in the bank balance, as unlike his wife, his deposits exceeded his withdrawals.
Your argument essentially ignores dFout, which means that the environment is taking more CO2 out of the atmosphere than it puts in; hence its contribution is negative.
Paul Birch says:
August 10, 2010 at 5:28 am
Paul Dennis says:
August 9, 2010 at 9:40 am
“Paul, I couldn’t disagree with you more. Any interpretation of the empirical data has to satisfy the observations.”
It is not sufficient that it satisfy the observations. It must not assume its conclusions.
There is no assumption of the conclusions in the mass balance model. Given our knowledge of the anthropogenic input, and the total CO2 content of the atmosphere there are 3 possible solutions:
1) d[CO2] > F(anthr) > 0 in which case the increase is a result of both anthropogenic and environmental fluxes.
2) 0< d[CO2] < F(anthr) in which case the increase is a result of anthropogenic fluxes alone.
3) d[CO2] < 0 in which case the sinks are greater than the combined environmental and anthropogenic fluxes.
The empirical data is Case 2. There is no a priori assumption of conclusions. At least not any that Ferdinand, Dikran or I can see.
Paul Birch wrote:
“It is not sufficient that it satisfy the observations. It must not assume its conclusions.”
The argument does not assume its conclusions, the chain of reasoning is as follows:
(i) conservation of mass means that
dC = E_anthropogenic + E_natural – U_natural
(ii) this implies that
E_natural – U_natural = dC – E_anthropogenic
(iii) we observe (figure 3 – red and blue lines), we observe that E_anthropogenic is greater than dC
(iv) if dC is less than E_anthropogenic, then (dC – E_anthropogenic) is negative, since it is already established that (E_natural – U_natural) is equal to (dC – E_anthropogenic), then (E_natural – U_natural) must be negative
(v) is (E_natural – U_natural) is negative then E_natural must be less than U_natural (as both are strictly positive quantities)
(v) as E_natural is less than U_natural, the environment must necessarily be a net sink, taking in more CO2 than it emits
(vi) As the natural environment is a net sink, it is opposing the observed rise rather than contributing to it, and hence cannot be a cause of the rise.
(vii) as man is a net source of CO2 into the atmosphere, anthropogenic emissions are A cause
(viii) there are only two possible causes, man and the environment (unless you consider acts of God or aliens from the planet Zog).
(ix) as we have established that the environment is not a cause (v) man must be the ONLY cause
There you are, the argument spelled out (yet again). It is a linear chain of steps, so there is no circular reasoning as every step depends only on those comming before it. The conclusion is not assumed, it only appears in the last step.
trrll says:
August 9, 2010 at 9:57 pm
“I think the most relevant measure of causality is, “what would happen to atmospheric CO2 levels if human CO2 emissions were zero?” If an increase of similar magnitude were to occur in the absence of human contribution to the CO2 mass balance, then it would be reasonable to say that human emissions are not the cause of the increase, regardless of what the mass balance might be. A lot of commenters clearly wish to believe this to be the case, but aside from quite a bit of vague hand-waving about how complicated the sources and sinks are, nobody has actually tried to propose a scenario. ”
First, what we wish is simply for the question to be addressed through sound science not through mere assumptions and fallacious reasoning. We have no emotional attachment to any particular outcome. Personally, I think I’d prefer it if human emissions could increase the atmospheric CO2 levels over time, because I’d prefer a world with much higher CO2 levels (say ~3,000ppm). Unfortunately, I suspect that we can’t, that there’s a (shifting) equilibrium we can’t do more than temporarily nudge. This is a particular irritation to me as it means there’s a flaw (though fortunately not a fatal one) in my published scenario for terraforming Mars. The prejudicial desire to blame mankind for the increase seems all on the other side of the table (and I use the word “blame” instead of something more neutral because they do seem to treat it as a negative).
Second, we have provided umpteen scenarios. They get ignored or rejected because they deny the fallacious dogma that the mass balance proves that the butler did it. In its simplest form, one hypothesis is that atmospheric CO2 levels are in (rough) equilibrium with a (variable) level set within the other reservoirs (by conditions such as temperatures, pH, nutrient levels, circulation, etc.). If human emissions increase, the natural sources and sinks will adjust to compensate and maintain the equilibrium. Since the human emissions comprise only a small fraction of the total flows into and out of the atmosphere, this would not be difficult. Nor is it hard to see how the feedback mechanisms would operate; if the atmospheric concentration goes high, the oceans will outgas less and dissolve more (Henry’s Law); if the CO2 levels go high, vegetation will grow faster and sequester more CO2. And vice versa. The difficulty with such scenarios is that the total capacity of the first rapidly reacting reservoirs (the sea surface and annual biomass) is limited, and the interchange with the almost unlimited deeper reservoirs may not be fast enough to eliminate significant lags or overshoots. But that is a matter for careful measurement and analysis, which cannot be achieved while the question-begging mass balance fallacy and the assumption of human responsibility for the secular changes dominates the thinking of those attempting the analysis.
Arthur Rörsch says:
August 10, 2010 at 3:08 am
Some simple calculations. All the fluxes are the same gas
Total IN = 12.89+7 =19.89
Fraction Fem=7/19.89=0.35
OUT and Fa will have the same composition.
Thus the Fa consists for 35 % of the anthropogenic emission = 1.225 GtC/y
Fa consists for 65 % of the other source dFin = 2.275 GtC/y (That is not a negative contribution. It is a substantial one)
Arthur, you are making the same essential error as many before you: the human emissions are only a tiny fraction of all inflows (about 8/150 GtC), but that doesn’t tell us anything about what the cause of the increase is. As Dikran already said: the sum of the outflows (153.5 GtC) exceeds the sum of all non-human inflows, thus the 150 GtC natural inflow is completely irrelevant for the increase of CO2 mass in the atmosphere, but it is relevant for the residence time, as this replaces (part) of the atmospheric CO2 with CO2 from other reservoirs.
Dikran, Ferdinand,
I’m afraid I’m going to have to leave this forum for about twenty hours shortly [sighs of relief all round …], so if I don’t manage to cover all the points before I go, I will come back at a later time.
I’ll try and address your points in order:
Dikran, August 10, 2010 at 3:24 am:
“I demonstrated that your redictio ad absurdum regarding the unknown volcanic island is incorrect” With respect, you didn’t.
“(ii) The observed rise is less than (or equal to) human emissions …” Yes. That is the scenario for both the island volcano and planet Zog.
The issue of whether or not we are dealing with a closed system (I think that is the first time you have mentioned it – I may be wrong) is a red herring – it doesn’t effect this particular argument.
“you need to make some assumptions” – but you have repeatedly said that the only assumption of the mass balance equation was that of the conservation of mass (later modified to include the assumption that humans are not significant extractors of CO2 from the environment). Now, when challenged another assumption arises – but it still does not answer the point.
Dikran August 10, 2010 at 4:52 am
“there is no other plausible source of the rise” But there you concede the point I am making. The island volcano and the planet Zog scenarios were deliberately absurd – ie not plausible. BUT in order to conclude that they could NOT be occurring you have to appeal to your wider environmental knowledge and conclude (correctly) that the scenarios are not plausible. It is NOT the mass balance equation that leads you to that conclusion because there is nothing inconsistent with the mass balance equation in the those absurd scenarios.
To emphasise this point, let me outline it again, just using the island volcano for brevity:
Here is your mass balance equation:
4 GtC = CO2(in1 + in2 + in3 +…) + 8 GtC – CO2(out1 + out2 + out3 +…)
and here it is again with the island volcano (IsV) , (which, remember, is producing 10X as much CO2 as humans, ie 80 GtC per year) and a few brackets for clarity, added:
4 GtC = {CO2(in1 + in2 + in3 +…) + 8 GtC + (IsV 80 GtC)} – {CO2(out1 + out2 + out3 +…) + (IsV 80 GtC)}
The mass balance equation accepts that situation with equanimity: there is NOTHING there that violates it or which, from the application of the equation and the law of conservation of mass (or indeed consideration of a closed system), would lead us to decide that the island volcano was an impossibility. In fact, its form is precisely what we would get if we accurately knew the fluxes for any other part of the carbon cycle, say, for example NH vegetation, and decided to quantify its place in the mass balance equation.
We decide that the island volcano is absurd, not from the mass balance equation, but from our knowledge of volcanoes, of CO2 sinks etc . That is the crucial point.
Your insistence that the mass balance equation, as you present it, ON ITS OWN shows that human emissions are the cause of the rise in atmospheric CO2 is WRONG. On it own, the mass balance equation shows that human emissions are more than able to account for the rise, but in order to show that they are actually the cause we have to use our knowledge of the wider environment, and its history, to make reasonable deductions. It is those latter, not the mass balance equation, that leads us to the conclusion that indeed human emissions are the cause of the rise in atmospheric CO2 (and that the island volcano scenario is completely implausible).
Ferdinand. Sorry, I seem to have missed you out of the fray – it was not intentional, but I’m afraid I have to go.
Sorry, the second mass balance equation would have been better written:
4 GtC = {CO2(in1 + in2 + in3 +…) + 8 GtC + (IsV 80 GtC)} – {CO2(out1 + out2 + out3 +…) + (out 80 GtC)}
where I should have explained that the “out 80 GtC” represents a sink of 80Gts CO2 somewhere in the environment that exactly balances the input from the volcano.
I have a business proposition for Arthur Rörsch, lets open a joint savings account; if you promise only to make deposits and no withdrawals, then I will promise to make a larger contribution to the increase in the balance than you do (according to your formula), and you get to keep all of the money in the account when it is closed. Can’t say fairer than that can I?
Of course I am only joking there, but once Arthur realises why I will make much more money out of that proposition than he will, perhaps he will spot the flaw in his logic.
For those who don’t want to know the answer, look away now:
Say Arthur invests 100 Euros per month and makes no withdrawals, as agreed. I then deposit 200 Euros per month, but then withdraw 275 Euros. The total of deposits into the account is 100+200 = 300 Euros per month, so according to Arthurs argument, his contrubution to the rise in the balance is 100/(100+200) = 1/3 and mine is 200/(100+200) = 2/3. So as agreed I am making a greater contribution to the rise in the balance than he is.
Is this a good scheme for Arthur to sign up to? NO! He gets to keep all of the increase, which accumulates at 25 Euro per month, but I am earning 75 Euros a month from the scheme 275 – 200 – 75. Works for me!!!! ;o)
So where is the error? Simple, Arthurs way of working out who is making the biggest contribution fails to consider the fact that I am making withdrawals from the account as well as deposits, and those withdrawals exceed the deposits. This is just like the natural environment which takes in more CO2 than it emits, but Arthurs formula takes no account of that, which is where the flaw in his reasonong lies. Here is a better estimate
Arthurs conthribution to the rise is (Arthurs deposits – Arthurs withdrawals)/(observed rise) = (100 – 0)/25 = 4. In other words, Arthurs contribution is 400% of the rise.
My contribution to the rise us (Dikran’s deposits – Dikrans withdrawals)/(observed rise) = (200 – 75)/25 = -3. In other words, I am responsible for -300% of the rise.
400% – 300% = 100% so we even have conservaion of Euros (provided aliens from the planet Zog haven’t been hacking in and messing around with the account).
Paul Birch says:
August 10, 2010 at 5:23 am
“That is the fundamental difference in our opinions:
The temperature would have increased the CO2 level in absence of human emissions. But it didn’t, because there were human emissions which were much larger than the observed increase (except for the period 1850-1900). “!
This is ridiculous. You have previously accepted (as your “definitive answer”) that “the increase in CO2 is man made” means “the increase would not have occurred if man had not emitted this CO2″. You can’t have it both ways.
You are taking the two sentences out of context, as I have explained in detail:
The current increase is certainly 100% man-made for the past 50 years. It is quite certainly man-made for the period 1900-1960 and it is uncertain for the period 1850-1900.
Without any human emissions, the temperature variations would have given the “normal” CO2 variations of about 8 ppmv/C on long term as seen in 800,000 years of ice cores. That may have influenced the 1850-1900 period, but probably not beyond that (1900-1960) and certainly not after 1960.
Other influences like volcanic eruptions are mostly short-term and hardly show up in the CO2 trend of the past 50 years, neither in high resolution ice cores (8 years) over the past 150 years, the period relevant for human emissions.
We are not doing anything of the sort. We are making no assumptions at all. We are saying we do not know; the mass balance, being only a single equation, cannot tell us to which of innumerable possibilities the cause of the increase should be ascribed. It might be the human emissions (in whole or in part). It might not. Feedbacks among the various subsyatems of the carbon cycle could, in principle, do practically anything.
The mass balance can’t tell us anything about what happens and happened within the natural world (with or without feedbacks), but it can tell us if the increase was solely man-made or a mix of human emissions and natural contribution or solely natural (if there was a decrease in the atmosphere).
In this scenario, the drain is a wide one, so this effect can be neglected. Yes, there will be a small residual variation from this cause, but the main cause of the rise in the drain is simply the rise in the lake. And as I have showed through other examples, even this residual term is not necessarily positive; where there are oscillatory flows (say, because the effluent, or the rain, comes in spurts) it can even be negative.
If the drain is a wide one (but still not superconductive), even a tiny fraction of a mm in/decrease can tell us what is the cause: As long as the increase in the drain is less than calculated from the factory’s effluent (and the resistance in the pipe), the lake level is down and the increase is from the effluent. If the level in the drain is negative, that shows that the level in the lake is even more down. If the level in the drain is more than calculated from the effluent, then the increase is from the lake + the effluent. In all cases, the mass balance gives us the right answer about the cause of the increase (or decrease) and we can even deduce the level in the lake from the height in the drain and the effluent flow…
This would generally be the case. Which is what we have been saying all along: “both natural and anthro sources and sinks [could] influence the CO2 level in the atmosphere”. Ascribing changes purely to the human component is completely fallacious. Note, by the way, that from the graphs you yourself posted above, it is quite apparent that the system can and does react strongly and rapidly – even over periods much less than a year, and in quantities considerably greater than annual human emissions, so it is entirely possible that the relevant lags are short and net human influence negligibly small.
Indeed both natural and human fluxes influence the CO2 level in the atmosphere, did we say something else? But again, we know (more or less accurate) the emissions, we know quite accurate the change of CO2 in the atmosphere. Thus we know more or less accurate the net effect of the natural carbon cycle (including all its variability). The net effect of the carbon cycle is negative over the past at least 50 years. May we then conclude that the contribution of the natural carbon cycle to the increase in the atmosphere at least over the past 50 years is (below) zero, or not?
Slioch says:
““I demonstrated that your redictio ad absurdum regarding the unknown volcanic island is incorrect” With respect, you didn’t.”
Sorry, I came here for an argument, that is just contradiction (Monty Python shibboleth – but see below for details)
““(ii) The observed rise is less than (or equal to) human emissions …” Yes. That is the scenario for both the island volcano and planet Zog.
The issue of whether or not we are dealing with a closed system (I think that is the first time you have mentioned it – I may be wrong) is a red herring – it doesn’t effect this particular argument.”
As I pointed out, an assumption of conservation of mass implies a closed system. It is meaningless to talk of conservation of mass in an open system as mass can leave or enter the system, so there is no reason for it to be conserved
““you need to make some assumptions” – but you have repeatedly said that the only assumption of the mass balance equation was that of the conservation of mass (later modified to include the assumption that humans are not significant extractors of CO2 from the environment). Now, when challenged another assumption arises – but it still does not answer the point.”
I was merely pointing out that no scientific theory can stand against the possibility of interference from unknown aliens from the planet Zog, or miracles or act of God etc. I said you need assumptions as well as observations to draw conclusions, and that is universally true (Hume killed pure empiricism stone dead). Nowhere did I introduce a new assumption, the only assuption needed to draw conclusions here is conservation of mass, nothing else (it just so happens that conservation of mass implies a closed system, which in turn excludes the intervention of aliens from the planet Zog).
“”there is no other plausible source of the rise” But there you concede the point I am making. The island volcano and the planet Zog scenarios were deliberately absurd – ie not plausible. BUT in order to conclude that they could NOT be occurring you have to appeal to your wider environmental knowledge and conclude (correctly) that the scenarios are not plausible. It is NOT the mass balance equation that leads you to that conclusion because there is nothing inconsistent with the mass balance equation in the those absurd scenarios.”
No, the aliens from Zog are inconsistent with the mass balance as conservation of mass requires a closed system.
If the volcano example is consistent with the mass balance argument then either:
(i) the emissions from the volcano are large enough that the environment becomes a net sink. In that case, as I have said, the mass balance argument confirms this as the observed rise is greater than the observed rise. But that is not what we observed.
(ii) Some other change in the natural environment ocurrs that takes in the excess CO2 from the volcano. In that case the natural environment is still a net sink and hence is opposing the rise in CO2.
This is demonstrated by your second post
“4 GtC = {CO2(in1 + in2 + in3 +…) + 8 GtC + (IsV 80 GtC)} – {CO2(out1 + out2 + out3 +…) + (out 80 GtC)}
where I should have explained that the “out 80 GtC” represents a sink of 80Gts CO2 somewhere in the environment that exactly balances the input from the volcano”
where you added an 80 Gtc uptake flux to cancel out the volcano. This means the natural environment as a whole is still a net sink, so how can the environment as a whole be a cause of the rise.
Remember the argument is: is the rise caused by man, or by the natural environment (which includes all volcanos, including undersea volcanos and unknown Pacific island volcanos) or is it both. If the natural environment is a net sink, it isn’t a cause.
Generally, when you have a steady state, and one of the inputs increases, a new steady state is established at a higher level. The accounting of mass balance is consistent with this. Outflows have increased to absorb some of the increased inflow due to human CO2 emissions, with the system in transition toward a new steady state at a higher level. One could, of course, imagine a system with strong, highly nonlinear, negative feedbacks such that outflows increase to absorb almost all of human emissions, and the steady-state level of atmospheric CO2 increases hardly at all. I think that it would be difficult to come up with natural mechanisms that would provide such a high degree of nonlinear negative feedback, but that question seems to be moot, because such a system would be recognizable by a mass balance of zero, which is not what the data shows.
trrll says:
August 10, 2010 at 8:22 am
Paul says: “If human emissions increase, the natural sources and sinks will adjust to compensate and maintain the equilibrium. Since the human emissions comprise only a small fraction of the total flows into and out of the atmosphere, this would not be difficult. Nor is it hard to see how the feedback mechanisms would operate; if the atmospheric concentration goes high, the oceans will outgas less and dissolve more (Henry’s Law); if the CO2 levels go high, vegetation will grow faster and sequester more CO2. And vice versa.”
trll says: “Generally, when you have a steady state, and one of the inputs increases, a new steady state is established at a higher level.”
Only if the feedback is weak. If the steady state is close to the equilibrium the effect of the inputs can be negligible.
“One could, of course, imagine a system with strong, highly nonlinear, negative feedbacks such that outflows increase to absorb almost all of human emissions, and the steady-state level of atmospheric CO2 increases hardly at all.”
It doesn’t require nonlinear feedback for this to happen (though that cannot be excluded). The absorption of CO2 through solution in water or through photosynthesis are more than powerful enough for this. This is clear from the graphs above. What is unclear is whether similar mechanisms extend to the other reservoirs.
” such a system would be recognizable by a mass balance of zero,”
No, it wouldn’t, not if the equilibrium position is varying exogenously! Which it almost certainly is, from changes in temperatures, pH, chemical composition, circulation, etc..
Ferdinand Engelbeen says:
August 10, 2010 at 8:01 am
“You are taking the two sentences out of context, as I have explained in detail:
The current increase is certainly 100% man-made for the past 50 years. It is quite certainly man-made for the period 1900-1960 and it is uncertain for the period 1850-1900.”
You are the one illegitimately shifting your meaning to suit your context. You are still trying to have things both ways. “The increase in CO2 is man made” means “the increase would not have occurred if man had not emitted this CO2″, over any period, in whole or in part. If the rise in temperature since 1900 would have caused any rise in CO2 over that period, then the increase is not 100% man made, because at least some of it would have happened anyway.
“If the drain is a wide one (but still not superconductive), even a tiny fraction of a mm in/decrease can tell us what is the cause: As long as the increase in the drain is less than calculated from the factory’s effluent (and the resistance in the pipe), the lake level is down and the increase is from the effluent.”
This is sheer lunacy. I’ve told you why the level in the drain is increasing. It’s because the level of the lake is increasing, due to higher rainfall. To within close limits, the two levels are the same, because water finds its own level! The increase in the volume of water in the drain is less than the volume of the factory’s effluent because the effluent doesn’t stay in the drain. It drains out to the lake. I can even make it that the factory’s effluent doesn’t raise the level of either the drain or the lake even microscopically, eg if the factory gets its water by capturing rain that would otherwise have entered the lake via the drain, or by drawing off lake water, etc..
Of course, one could easily imagine another scenario in which the factory output was too much for the drain, and then the effluent could indeed be the main cause of the rise in the drain. But my scenario is entirely feasible too. The crucial point is that it is not possible to distinguish between those scenarios simply by measuring the level in the drain and the volume of effluent. Not unless we can carry out a controlled experiment increasing and decreasing the volume of effluent while holding the level of the lake constant (which, in the case of CO2, we can’t).
Paul Birch says
“No, it wouldn’t, not if the equilibrium position is varying exogenously! Which it almost certainly is, from changes in temperatures, pH, chemical composition, circulation, etc.”
So your hypothesis is that there would have been a feedback to increase outflow sufficiently to remove all of the CO2 added to the atmosphere by humans, except that for some reason the equilibrium point is coincidentally shifting up in parallel with human CO2 release? And that if humans had not added CO2 to the atmosphere, then natural inflows would have increased or outflows would have decreased to create a net +4GtC/y mass balance?
I’m a bit unclear as to what you mean by the equilibrium point shifting exogenously, however, since the equilibrium (I’m presuming you mean steady-state) point is not normally imposed exogenously, but rather determined by the inflows and outflows, which are taken into account by the mass balance.
Paul Birch says:
August 10, 2010 at 8:46 am
trll says: “Generally, when you have a steady state, and one of the inputs increases, a new steady state is established at a higher level.”
Only if the feedback is weak. If the steady state is close to the equilibrium the effect of the inputs can be negligible.
What you are saying here is that the human emissions are readily absorbed, but that the equilibrium shifts upward. Theoretically, that is possible, in reality very unlikely. That doesn’t change the fact that the mass balance still would show that the rise is human-only, as there is less increase than the emissions.
It doesn’t require nonlinear feedback for this to happen (though that cannot be excluded). The absorption of CO2 through solution in water or through photosynthesis are more than powerful enough for this. This is clear from the graphs above. What is unclear is whether similar mechanisms extend to the other reservoirs.
Again, you are confusing between the height of the fluxes, both from photosynthesis and absorption/release of the oceans as result of the seasonal temperature changes and the net result of these reversing (and opposite) fluxes at the end of the year: The fluxes are huge, but the opposite effect shows a very moderate amplitude: 4 ppmv/C, half the human emissions.
The net absorption of the upper oceans is around 0.8 GtC/year, the net absorption of the deep oceans is around 2 GtC/year and the net absorption by vegetation is around 1.2 GtC/year. That is because the ocean surface is limited by chemical equilibria, the deep oceans has limited exchanges with the atmosphere and vegetation growth indeed increases with more CO2, but doesn’t double for a doubling of CO2.
The other reservoirs even are (much) slower in absorption/release.
But these items will come for discussion some day, if we can end this one…
” such a system would be recognizable by a mass balance of zero,”
No, it wouldn’t, not if the equilibrium position is varying exogenously! Which it almost certainly is, from changes in temperatures, pH, chemical composition, circulation, etc..
Even if the equilibrium position shifted (as is the case for the upper ocean layer), any such change must fit all the observed criteria, including the mass balance. And as long as the measured increase in the atmosphere is less than the emissions, all changes in the natural carbon cycle, whatever the cause, still don’t result in a net contribution.
Paul Birch says:
August 10, 2010 at 6:21 am
The prejudicial desire to blame mankind for the increase seems all on the other side of the table (and I use the word “blame” instead of something more neutral because they do seem to treat it as a negative).
Please no reference to motives here (see the rules…). I would even like more effect from more CO2 in the atmosphere on the average temperature where I live… But that doesn’t mean that we shouldn’t weight the evidence pro and con where humans are responsible for and where not.
trrllsaid: “I’m a bit unclear as to what you mean by the equilibrium point shifting exogenously,”
I suspect by exogenously he means that the change in equilibrium point was the response of the carbon cycle to a change of external forcing (such as a change in solar forcing) that is not part of the natural carbon cycle. However, the fact that the observed environmental flux is negative and atmospheric CO2 is still rising is a good indication that the current levels are above the current equilibrium point. I would agree that the current equilibrium point would be different from the pre-industrial equilibrium point as anthropogenic emissions mean that there is more carbon going round the carbon cycle now then there was then, so it is reasonable to assume the excess will be shared between the major reservoirs, including the atmosphere, and so the equilibrium point would be higher. That would be an example of an exogenous change as anthropogenic emissions are not part of the natural carbon cycle, so the change is a response to an external peturbation.
Dikran Marsupial writes “the fact that the observed environmental flux is negative and atmospheric CO2 is still rising is a good indication that the current levels are above the current equilibrium point”
You are right. This eliminates the hypothesis that the rise is due to the system moving toward a new, higher steady-state. The negative flux indicates that whether or not the steady-state point is rising, CO2 has already overshot that level. That being the case, there does not seem to be any way in which the current increase could occur in the absence of human input, which satisfies any reasonable criterion for causality.
“That would be an example of an exogenous change as anthropogenic emissions are not part of the natural carbon cycle, so the change is a response to an external peturbation.”
Certainly, human emissions will push the system toward a higher steady-state. I was thinking that by exogenous, he also meant separate from the anthropogenic contribution, since (I think) he was arguing that atmospheric CO2 would still be increasing to a similar extent if human CO2 emissions were absent.
Paul Birch says:
August 10, 2010 at 9:22 am
You are the one illegitimately shifting your meaning to suit your context. You are still trying to have things both ways. “The increase in CO2 is man made” means “the increase would not have occurred if man had not emitted this CO2″, over any period, in whole or in part. If the rise in temperature since 1900 would have caused any rise in CO2 over that period, then the increase is not 100% man made, because at least some of it would have happened anyway.
Paul, you are becoming irritant. It is quite easy to try to score points by going into details which are quite different from what you try to make of them.
The rise in temperature since 1900 would have given a small rise in CO2 if there were no emissions.
But as the mass balance (reasonably certain for 1900-1960 and very certain for 1960-current) shows that for the full period 1900-current there was less increase in the atmosphere than emitted by humans, there is no net contribution to the increase from the change in temperature or any other natural change in equilibrium: pH, chemical composition, photosynthesis, or any other natural change resulting in a change of inflows and/or outflows. Simply because the natural outflows over the full period were larger than the natural inflows. In all these years, nature was a net sink for CO2, despite the increase in temperature.
“If the drain is a wide one (but still not superconductive), even a tiny fraction of a mm in/decrease can tell us what is the cause: As long as the increase in the drain is less than calculated from the factory’s effluent (and the resistance in the pipe), the lake level is down and the increase is from the effluent.”
This is sheer lunacy. I’ve told you why the level in the drain is increasing. It’s because the level of the lake is increasing, due to higher rainfall. To within close limits, the two levels are the same, because water finds its own level! The increase in the volume of water in the drain is less than the volume of the factory’s effluent because the effluent doesn’t stay in the drain. It drains out to the lake. I can even make it that the factory’s effluent doesn’t raise the level of either the drain or the lake even microscopically, eg if the factory gets its water by capturing rain that would otherwise have entered the lake via the drain, or by drawing off lake water, etc..
Paul, I did only show that one can know what happened in the lake, if one knows the amount of effluent and the resistance in the drainpipe to calculate that the lake was filling up or its level was falling, without knowing anything else about the height or variability of the lake’s further inflows or outflows, including rain or drought. Simple math, a little more complicated than the simple mass balance for knowing the influence from the carbon cycle on the increase of CO2 in the atmosphere: a net sink.
Of course, one could easily imagine another scenario in which the factory output was too much for the drain, and then the effluent could indeed be the main cause of the rise in the drain. But my scenario is entirely feasible too. The crucial point is that it is not possible to distinguish between those scenarios simply by measuring the level in the drain and the volume of effluent. Not unless we can carry out a controlled experiment increasing and decreasing the volume of effluent while holding the level of the lake constant (which, in the case of CO2, we can’t).
If you make a clear (mechanical) separation between the effluent and the rest (thus no rain in the drain), it is quite easy to calculate the height of the lake.
If you make a clear (mathematical) separation between the human emissions (and sinks) at one side and the natural emissions and sinks at the other side it is even a much simpler calculation to know if the increase in the atmosphere is partly man-made or fully man-made. Or that nature is absorbing everything, man-made or not, when there is a decrease of CO2 in the atmosphere.
See what Paul Dennis wrote on August 10, 2010 at 6:04 am
trrll says:
August 10, 2010 at 11:35 am
Paul Birch says: “No, it wouldn’t, not if the equilibrium position is varying exogenously! Which it almost certainly is, from changes in temperatures, pH, chemical composition, circulation, etc.”
“So your hypothesis is that there would have been a feedback to increase outflow sufficiently to remove all of the CO2 added to the atmosphere by humans, except that for some reason the equilibrium point is coincidentally shifting up in parallel with human CO2 release? And that if humans had not added CO2 to the atmosphere, then natural inflows would have increased or outflows would have decreased to create a net +4GtC/y mass balance?”
That is one possible hypothesis out of many (it’s not all or nothing). The increase in CO2 levels in the atmosphere is not that well correlated with the rate of human emissions – they are both broad brush trends over the century, but with CO2 levels continuing to rise even during recessions – so the coincidence would not be great. They correlate a little better with sea surface temperatures, though that could be coincidence too. Note that the mass balance doesn’t have to be spot on every year – there’s a lot of variation in those graphs – just more or less right over the longer run.
Again, I’m not saying that there may not be evidence that, validly interpreted without prejudice or logical fallacies, might falsify this or other hypotheses; but we have to get rid of the fallacies and unwarranted assumption first before we could properly consider them.
“I’m a bit unclear as to what you mean by the equilibrium point shifting exogenously, however, since the equilibrium (I’m presuming you mean steady-state) point is not normally imposed exogenously, but rather determined by the inflows and outflows, which are taken into account by the mass balance.”
No, I don’t mean merely a steady state, as a resultant of inflows and outflows. I mean an equilibrium point, maintaining itself by modifying the inflows and outflows, like the concentration of salt in a saturated solution. By exogenous, I mean that at least some of the parameters controlling the position of the equilibrium are external to the carbon cycle as such – things like sea temperatures and circulation patterns. By shifting, I mean that the equilibrium point is not fixed; when the temperatures and circulation patterns change, it changes. When the temperature goes up, it goes up, and so forth.
Paul Birch says:
August 10, 2010 at 9:22 am
“The increase in CO2 is man made” means “the increase would not have occurred if man had not emitted this CO2″, “over any period, in whole or in part. If the rise in temperature since 1900 would have caused any rise in CO2 over that period, then the increase is not 100% man made, because at least some of it would have happened anyway.”
It is possible that the rise in temperature since 1900 was the result of anthropogenic GHG radiative forcing, in which case the temperature rise would not have happened if not for anthropogenic CO2. That means you cannot assert that a rise CO2 due to temperature change would have happened anyway as you don’t know that the temperature rise would have happened without the anthropogenic emissions. Note I said it was possible, not that it did, just pointing out that there was a hidden assumption in the argument.
I also disagree with your definition of causal, mine is based on what actually did happen, not what might have happened. The mass balance argument tells you what actually DID happen, which is that for the last fifty years the natural environment has taken in more CO2 than it emitted and therefore has not contributed anything at all to the rise – nothing.
I would hesitate to go as far as to say this means the rise wouldn’t have happened if not for anthropogenic emissions as it is impossible to say with complete certainty what would have happened – and neither can you. There may be some mechanism in climate physics for which there is no evidence in paleoclimate data that could account for it, or aliens from the planet Zob might have caused the rise had we not done so, or there may have been an eruption of several mega-volcanos (Deccan traps style). However, there is little reason to suppose that the rise would have happened, even the assumption that the rise in temperature would have caused the rise is only an assumption, you don’t KNOW it would have happened.
Paul Birch writes “That is one possible hypothesis out of many (it’s not all or nothing). “
Now I’m curious. For atmospheric CO2 to have increased to a similar extent in the absence of human CO2 emissions, I see no options other than an increase in other inflows, a decrease in outflows, or some combination of the two. What are a few of the “many” other hypotheses that would produce this result?
“No, I don’t mean merely a steady state, as a resultant of inflows and outflows. I mean an equilibrium point, maintaining itself by modifying the inflows and outflows, like the concentration of salt in a saturated solution.”
By definition, for a system to be at equilibrium, there can be no irreversible reactions or energy inputs. But burning fossil fuel to liberate CO2 is irreversible, and there are also natural processes that are thermodynamically irreversible (volcanic eruptions, for example), so it seems like the best you can have is a steady state.
Dikran Marsupial:
August 10, 2010 at 8:08 am
Back to the fray.
Firstly: “I came here for an argument, that is just contradiction”
Well, actually, my bald rejection was in response to your bald assertion, so I think we are about quits on that score.
But to return to the matter of substance. Can the mass balance equation on its own determine whether human emissions are responsible for the rise in atmospheric CO2, as you maintain, or does it require additional information from the wider environment, as I maintain?
In other words, is the correct conclusion from your above article, “humans have added about twice the amount of CO2 to the atmosphere as the observed increase over the past 150 years, … . That is sufficient PROOF [my emphasis] for the human origin of the increase … ” as you and Ferdinand maintain?
Or is the correct conclusion that, “humans have added about twice the amount of CO2 to the atmosphere as the observed increase over the past 150 years, which means that the human emissions are more than able to explain the increase in atmospheric CO2”, as I maintain?
This may seem a trivial hair-splitting point to some (not yourself I think), but it is not. We both agree (I assume) that it is important for people to accept the human causality behind the recent rise in atmospheric CO2. It is therefore important to present an argument that does not contain a logical flaw. I believe your mass balance argument does contain such a flaw.
Here is, I believe, proof of that logical flaw:
We start with the same bits of information as previously:
8Gts/year human emissions of CO2 to the atmosphere
4Gts/year net gain in atmospheric CO2
80Gts/year emission of CO2 from a volcano “somewhere in the Pacific”.
Dikran doesn’t know about the volcano, he uses the mass balance equation thus:
4 GtC = CO2(in1 + in2 + in3 +…) + 8 GtC[HE] – CO2(out1 + out2 + out3 +…)
(I’ve added a [HE] (Human Emissions) label for clarity)
which is certainly valid, and he concludes from it that all factors other than human emissions are acting together as a net sink, which also valid. Therefore, according to Dikran/Ferdinand that is sufficient proof for the human origin of the increase.
Narkid, on the other hand (being a contrary kind of guy), doesn’t know about human emissions, but he does know about the volcano. So he write this mass balance equation:
4 GtC = CO2(in1 + in2 + in3 +…) + 80 GtC[Vol] – CO2(out1 + out2 + out3 +…)
which is certainly valid, and he concludes from it that all factors other than the volcano are acting together as a net sink, which is also valid. Therefore, according to Narkid that is sufficient proof for the volcanic origin of the increase.
So, Dikran “proves” that human emissions are uniquely responsible for the increase.
and Narkid “proves” that the volcano is uniquely responsible for the increase.
Both “proofs” are equally valid (or invalid). But it is impossible for one event to be caused by two causes: it is impossible to claim that the rise in atmospheric CO2 is uniquely caused by human emissions and also to claim that it is uniquely caused by the volcano.
The only possibility therefore is that neither Dikran’s nor Narkid’s proofs are valid. The mass balance equation does not prove that human emissions are the cause of the rise in atmospheric CO2. The most that can be said from the mass balance equation alone is that human emissions are more than able to explain the rise in atmospheric CO2.
In order to identify human emissions as responsible for the rise in atmospheric CO2 we need additional information from the environment – for example, that no other possible source of CO2 could be responsible (eg. that the volcano does not exist). Such information is not included in the mass balance equation and it alone therefore cannot provide such proof.
Ferdinand Engelbeen says:
August 10, 2010 at 7:07 am
“Arthur, you are making the same essential error as many before you: the human emissions are only a tiny fraction of all inflows (about 8/150 GtC), but that doesn’t tell us anything about what the cause of the increase is. As Dikran already said: the sum of the outflows (153.5 GtC) exceeds the sum of all non-human inflows, thus the 150 GtC natural inflow is completely irrelevant for the increase of CO2 mass in the atmosphere, but it is relevant for the residence time, as this replaces (part) of the atmospheric CO2 with CO2 from other reservoirs.”
I admit that my former calculation
“Thus the Fa consists for 35 % of the anthropogenic emission = 1.225 GtC/y
Fa consists for 65 % of the other source dFin = 2.275 GtC/y (That is not a negative contribution. It is a substantial one)”
is wrong. I hope to do better soon by falling back on former calculations which indicated that theoretically the anthropogenic component must be (even) much less. (6 %). And that figure (even) does not match with observations in the ocean mixing layer (2%).
So I agree with you in principle that this kind of calculations do not prove any cause. But I still think neither the ‘balance’ considerations. (I will elaborate later, trying to follow again your way of reasoning.). But the fact remains that a tiny fraction of extra inflow (8/150) seems to disturb the system in such a way, that (also) non anthropogenic CO2 is accumulating strongly. That makes many people think by intuition that the extra inflow can not be the only cause of accumulation and do search for other causes of the unbalance, with many different in and outflows in the system and reservoirs that store the CO2 above the deep sea. In this respect I have a question. Does anybody has a figure for the increased ‘greening’ of the planet? I remember that Ahlbeck once showed that this increase coincides with the raise of CO2 in the atmosphere and temperature rise over the last decades, even with the annual fluctuations. According to the scheme in your original post, the green + soil reservoir is pretty large compared to that of the atmosphere and the ocean mixing layer.
trrll says:
August 10, 2010 at 10:01 pm
Paul Birch writes “That is one possible hypothesis out of many (it’s not all or nothing).”
trrll says: “Now I’m curious. For atmospheric CO2 to have increased to a similar extent in the absence of human CO2 emissions, I see no options other than an increase in other inflows, a decrease in outflows, or some combination of the two. What are a few of the “many” other hypotheses that would produce this result?”
Sorry, I meant that one possible hypothesis is the hypothesis that CO2 levels would have increased by the same amount with human emissions. Other possible hypotheses are that the CO2 levels would have increased or decreased in various different ways. The null hypothesis is that they wouldn’t have changed at all. Many intermediate outcomes are possible – that’s why I said it’s not all or nothing – but all of them are consistent with the mass balance.
… Though as a matter of fact, I could also invent weird hypotheses that didn’t rely upon changes in the sources and sinks of CO2 – such as an increase in the mass of the atmosphere (reducing CO2 concentrations for a given mass of CO2). This could occur with or without an increase in atmospheric pressure. An increase in the surface area of the Earth would allow a greater atmospheric mass for the same atmospheric pressure. So would a decrease in Earth’s gravity, or a combination of the two. Then again, which sources and sinks? Maybe there are others we haven’t included, like the about to be discovered interdimensional gateways to parallel Earths. What do you mean, you’ve never heard of them? My point here is that (on top of the basic logical error) there are numerous hidden assumptions in the mass-balance argument. They all need to be confirmed (or disconfirmed) through hard independent evidence, with analytic methods that do not assume their conclusions.
Paul says: “No, I don’t mean merely a steady state, as a resultant of inflows and outflows. I mean an equilibrium point, maintaining itself by modifying the inflows and outflows, like the concentration of salt in a saturated solution.”
trll says: “By definition, for a system to be at equilibrium, there can be no irreversible reactions or energy inputs. But burning fossil fuel to liberate CO2 is irreversible, and there are also natural processes that are thermodynamically irreversible (volcanic eruptions, for example), so it seems like the best you can have is a steady state.”
I don’t mean that there has to be a complete thermodynamic equilibrium encompassing the entire system. You can add trickle in hot brine and cold water to a solution and watch the salt precipitate out, but the concentration of salt in the bulk of the solution depends only on its temperature, not the rate at which salt is moving through the system.
The level of water in your cistern is an equilibrium level. If you open a tap, draining some water out of the cistern, the ballcock opens letting more water in. Except momentarily, for very high rates of flow, such as when you flush your toilet, the water level does not depend upon the rate at which you use the water, or the rate at which the mains can supply water. It depends only on the ballcock’s position and buoyancy. Over time, though, as deposits build up on the ball, the level can shift “exogenously”.
The level of water in your leaking bucket, by contrast, is no equilibrium but only a rate-determined steady state. It depends on how big the leak is and how fast you run the tap to fill it.
The real carbon cycle probably has both equilibria and rate-limiting steps.