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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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CO2 emissions change our atmosphere for centuries

What the science says...

Individual carbon dioxide molecules have a short life time of around 5 years in the atmosphere. However, when they leave the atmosphere, they're simply swapping places with carbon dioxide in the ocean. The final amount of extra CO2 that remains in the atmosphere stays there on a time scale of centuries.

Climate Myth...

CO2 has a short residence time

"[T]he overwhelming majority of peer-reviewed studies  [find] that CO2 in the atmosphere remained there a short time." (Lawrence Solomon)

The claim goes like this:

(A) Predictions for the Global Warming Potential (GWP) by the IPCC express the warming effect CO2 has over several time scales; 20, 100 and 500 years.
(B) But CO2 has only a 5 year life time in the atmosphere.
(C) Therefore CO2 cannot cause the long term warming predicted by the IPCC.

This claim is false. (A) is true. (B) is also true. But B is irrelevant and misleading so it does not follow that C is therefore true.

The claim hinges on what life time means. To understand this, we have to first understand what a box model is: In an environmental context, systems are often described by simplified box models. A simple example (from school days) of the water cycle would have just 3 boxes: clouds, rivers, and the ocean.

A representation of the carbon cycle (ignore the numbers for now) would look like this one from NASA.

In the IPCC 4th Assessment Report glossary, "lifetime" has several related meanings. The most relevant one is:

“Turnover time (T) (also called global atmospheric lifetime) is the ratio of the mass M of a reservoir (e.g., a gaseous compound in the atmosphere) and the total rate of removal S from the reservoir: T = M / S. For each removal process, separate turnover times can be defined. In soil carbon biology, this is referred to as Mean Residence Time.”

In other words, life time is the average time an individual particle spends in a given box. It is calculated as the size of box (reservoir) divided by the overall rate of flow into (or out of) a box. The IPCC Third Assessment Report 4.1.4 gives more details.

In the carbon cycle diagram above, there are two sets of numbers. The black numbers are the size, in gigatonnes of carbon (GtC), of the box. The purple numbers are the fluxes (or rate of flow) to and from a box in gigatonnes of carbon per year (Gt/y).

A little quick counting shows that about 200 Gt C leaves and enters the atmosphere each year. As a first approximation then, given the reservoir size of 750 Gt, we can work out that the residence time of a given molecule of CO2 is 750 Gt C / 200 Gt C y-1 = about 3-4 years. (However, careful counting up of the sources (supply) and sinks (removal) shows that there is a net imbalance; carbon in the atmosphere is increasing by about 3.3 Gt per year).

It is true that an individual molecule of CO2 has a short residence time in the atmosphere. However, in most cases when a molecule of CO2 leaves the atmosphere it is simply swapping places with one in the ocean. Thus, the warming potential of CO2 has very little to do with the residence time of CO2.

What really governs the warming potential is how long the extra CO2 remains in the atmosphere. CO2 is essentially chemically inert in the atmosphere and is only removed by biological uptake and by dissolving into the ocean. Biological uptake (with the exception of fossil fuel formation) is carbon neutral: Every tree that grows will eventually die and decompose, thereby releasing CO2. (Yes, there are maybe some gains to be made from reforestation but they are probably minor compared to fossil fuel releases).

Dissolution of CO2 into the oceans is fast but the problem is that the top of the ocean is “getting full” and the bottleneck is thus the transfer of carbon from surface waters to the deep ocean. This transfer largely occurs by the slow ocean basin circulation and turn over (*3). This turnover takes 500-1000ish years. Therefore a time scale for CO2 warming potential out as far as 500 years is entirely reasonable (See IPCC 4th Assessment Report Section 2.10).

Intermediate rebuttal written by Doug Mackie


Update July 2015:

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 5 July 2015 by skeptickev. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Update

Updated 'the skeptic argument' on 02/05/2012 to correct formatting errors

Comments

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Comments 51 to 94 out of 94:

  1. drrocket, the IPCC diagram that we both linked above is misleading and I should have said so instead of saying the red arrows are the "new" or ACO2. Going from the atmosphere to the ocean there 22.2 red down and 20 red up. And there is 70 black down, 70.6 black up. Those ratios cannot be different since the ocean is nonpreferential. Nor are those arrows equal ratios of the reservoirs, not that it matters. The simplest explanation of the red down and up arrows is that they wanted to show some amount of CO2 exchange but wanted the net exchange to equal 2.2 down or about 1/3 of the 6.4 from fossil fuels. Net red transfer cannot possibly differ from net black transfer, but they ignored that fact and made it different. Other than that correction, my closing remark above still stands. I didn't justify it, but other people in the thread did. It is not shilling for this site, but my own conclusion from a few facts. One fact is that the 6.4 GtC/yr released by fossil fuels and cement is an accurate estimate. The second fact is that the year to year increase in the atmosphere is about 1.9 ppm measured at numerous locations. The first fact means that the atmosphere should rise by about 3.6 ppm. The second fact means that the ocean and biosphere is absorbing some of that 3.6 so we only see 1.9 remain in the atmosphere on a yearly basis.
  2. "I would have no use for adjustment time under any circumstances because the climate system never reaches equilibrium. " The fact that the atmosphere is not now in equilibrium has no bearing on this debate. That is a red herring. The residence time also has almost no bearing on how quickly the CO2 added to the atmosphere will be absorbed by the biosphere. What matters are net exchanges between the atmosphere and the terrestrial and oceanic reservoirs and how those net exchanges have changed with increasing pCO2. These net exchanges are small relative to the atmospheric reservoir. You are misinterpreting the phrase 'anthropogenic fluxes' in the IPCC graph. The 'anthropogenic fluxes' are simply the difference between pre and post industrial fluxes. It does not refer to fates of carbon dioxide molecules specifically produced by natural or anthropogenic carbon emissions - although I can see where the confusion arises. Basically the fluxes into the ocean have increased due to the effects of increasing pCO2 on solution chemistry. On land net losses have increased due to forect conversion and inputs have increased slightly because of CO2 fertilization (yes, skeptics, it is accounted for). It's that simple. This usage of "anthropogenic fluxes" makes sense to scientists, because it is the only way to discuss the effect of humans on the carbon cycle. The idea that these processes don't discriminate between natural and anthropogenic carbon is a given to them, and it's ludicrous to suggest that the scientists are trying to pull the wool over your eyes on that front. The reason the confusion is arising is precisely because it wouldn't even enter their minds that someone would consider that possibility. They are naive that way (and I include myself in that judgement). Your outrage is misplaced.
  3. Previous post addressed to drrocket @ 49
  4. drrocket@50 I made no such assumption, the fact that the natural environment is a net sink, not an emitter is a conclusion, not a premise. The observed annual rise is less than anthropogenic emissions, therefore the natural environment must be a net sink. "I would have no use for adjustment time under any circumstances because the climate system never reaches equilibrium." This is a silly statement, the adjustment time describes the accumulation or dissapation of atmospheric CO2, not the residence time. This is true whether the system reaches equilibrium or not. The average time molecules stay in the atmosphere is irrelevant, becuase almost all of the flux out of the atmosphere is an exchange of carbon with the oceans/terrestrial bioshpehe, not an uptake. If carbon is only being exchanged between reservoirs, it has no effect on atmospheric CO2 levels, and hence is entirely irrelevant. As I said, like Essenhigh, you are confusing residence time with adjustment time. It is adjustment time that matters. "It's missing E_a altogether." As E_a is in my equation, I suspect you mean U_a. The reason for that is U_a, which represents uptake of carbon by anthropogenic means, is negligible compared to anthropogenic emissions. How much carbon sequestration are we doing at the moment? Very little. If you assume that U_a = 0.6E_a then you obviously don't understand the mass balance equation. U_a would be the amount of carbon taken out of the atmosphere each year by our activity rather than by natural mechanisms (i.e. essentially zilch). It is not the amount of anthropogenic CO2 taken up by the environment. "If you have any accountancy homework, just post it here, too, for lessons. " You still have not risen to the challenge, so I wouldn't be so cocky if I were you. The challenge was to provide values for E_a, E_n, U_n and dC, where the natural environment was a net source (i.e. E_n > u_n) but where the annual rise in CO2 was less than anthropogenic emissions (i.e. dC < E_a). You won't be able to do so, for the simple reason that it is mathematically impossible, and that is how we know for sure that the natural environment is a net sink. Go on, all you need to do is provide those four numbers, if you are right and the natural envionment is the cause of the aobserved rise, you ought to have no problem doing so.
  5. Eric (skeptic), 5/13/11, 11:35 AM I agree that AR4 Figure 7.3 is not altogether sterling. The partitioning of air-sea fluxes I take with a grain of salt, and I have not relied on it. I accept the 6.4 GtC/yr from fossil fuels at face value along with the totals of 92.2 GtC/yr into the ocean and 90.6 outgassed. IPCC puts the natural or background land-air flux 119.9 ± 1 GtC/yr, an imbalance of 0.83%. It puts the natural air-sea flux at 70.3 ± 0.3 GtC/yr, an imbalance of 0.43%. If we were to add another 20 GtC/yr shown in red, the air-sea flux would be 90.3 ± 0.3, an imbalance of 0.33%. IPCC puts the ACO2 flux at 28 GtC/yr up and 24.8 down, or 26.4 ± 1.6, an imbalance of 3.2%. If we deduct the questionable 20 GtC/yr, we have 6.4 ± 1.6, an imbalance of 12.5% for ACO2. In most references to these fluxes, the 20 GtC/yr is not included, yielding 8 up and 4.8 down, and the ratio is given in terms of full scale, 4.8/8 = 40% of ACO2 absorbed in the land-sea surface. IPCC shows the preference both in its mass balance results and in its equilibrium chemistry. No matter how you slice the baloney, IPCC claims the land-sea surface has a huge preference for nCO2 over ACO2, and in the last analysis, that's why we ought to curtail CO2 emissions. You write about what IPCC "wanted to show". What I take away from the chart is it wanted to show that the natural C cycle was in mass balance (it uses the term equilibrium) while the anthropogenic C cycle accumulates ACO2 in the atmosphere. You and I agree that the ocean is nonpreferential between these species. I extend that nonpreferential property from the fluxes to the relative rates of absorption. If the rate of absorption of ACO2 is only 50% of the rate of emission, that should be true of nCO2 also. IPCC's entire equilibrium chemistry justification for this preference is fatally flawed for two reasons. First, the stoichiometric equilibrium coefficients are not applicable. Secondly, IPCC applies its carbonate chemical analysis only to ACO2 and not nCO2.
  6. drrocket "No matter how you slice the baloney, IPCC claims the land-sea surface has a huge preference for nCO2 over ACO2, and in the last analysis, that's why we ought to curtail CO2 emissions" As I explained above in 52, you and Eric are misinterpreting the actual meaning of 'anthropogenic' fluxes used by the IPCC. 'Anthropogenic' (notice how they use quotation markes) fluxes simply refer to the change in rates that has occured because pCO2 in the atmosphere has increased and landuse changes have occured. When pCO2 increased over perindustrial, there was an increase in net CO2 flux into the ocean. That is a well established chemical and physiological response to changes in CO2 concentrations. Those changes would have occured if CO2 were released from methane hydrates, volcanoes or if it spontaneously arose out of thin air. The numbers would be the same. I repeat...There is nothing special about anthropogenic carbon. The IPCC graph does not imply in anyway that there is. "The partitioning of air-sea fluxes I take with a grain of salt, and I have not relied on it." It is interesting that you drop perhaps a number we can constrain well with current measurements (i.e., the flux into the ocean under current conditions) but accept instead a number that is only a projection to past conditions, albeit one based on good understanding of physical and chemistry. That is an arbitrary decision.
  7. Stephen, they are in fact not fluxes? IOW, the red arrows are differences between natural and present fluxes, but do not represent actual fluxes.

    drrocket, what I gave as an argument (I am mostly just paraphrasing Englebeen's argument) and what Dikran Marsupial and others said previously in no way depends on prefential absorption. The IPCC's misleading diagram does not form the basis for what I said or what Dikran said, we simply observe the total ACO2 estimate (from reliable estimates of power generation and fuel sources, transportation uses, cement making, etc); and the total atmospheric buildup from reliable measurements. The ACO2 is about double the atmospheric increase. There is no isotope ratio argument or any references to carbon fluxes other than those two.

    Response: [Dikran Marsupial] Indeed, I downloaded data on land use and FF emissions from the Carbon Dioxide Information and Analysis Center, and CO2 data from the MLO so I could verify the mass balance argument is correct (which it is). The story is similar if you use the other monitoring stations - even WUWT had a post a while back explaining that the MLO data were reliable, which puts into perspective how far out on a limb you have to be not to accept it!
  8. Eric...yes, the red lines are differences in fluxes pre and post industrial. Those differences represent the anthropogenic changes to the fluxes, not the fluxes of anthropogenic carbon. The thing we actually measure/estimate are the current fluxes/pools (the sum of red and black). The natural preindustrial levels are actually backcasts - some of which are well measured and other estimated based on reasonable constraints. Because CO2 was pretty steady during most of this interglacial, those preindustrial solutions are constrained to balance (inputs to atmosphere ~ outputs from atmosphere). That balancing assumption does not hold under current conditions because the system is out of equilibrium. The graph is an attempt to tease apart the effect of humans on the carbon cycle fluxes resulting from this shift to non-equilibrium conditions. There is no indication in that graph that aCo2 and nCO2 behave differently. To measure fluxes of anthropogenic carbon specifically, you would multiply the fluxes by the % of each source reservoir that is anthropogenic carbon. Don't be misled though. That ratio is not related to the red:black pool sizes, as those red numbers in the pools also simply reflect a difference in pool sizes pre and post industrial. If you did that you would find that there is net movement of aCO2 into the oceans simply because the fraction of the atmospheric C that is derived from human activities is larger for the atmosphere than for the ocean. That number is really only interesting to those looking at isotope tracers though. It's the changes in the pool sizes and fluxes that actually matter to the carbon cycle. Why? Precisely because nature does not care if its aCO2 or nCO2. I'll have to say, when I saw this graph before reading the background material, I too was puzzled by what it actually meant. It makes perfect sense from an academic viewpoint, though. Tracing aCO2 is actually less informative in many ways.
  9. drrocket@55 wrote: "If the rate of absorption of ACO2 is only 50% of the rate of emission, that should be true of nCO2 also. " This is incorrect, the IPCC do not say that the rate of absorption of ACO2 is only 50%. They say that the annual increase in atmospheric CO2 is about half anthropogenic emissions, but that doesn't mean that half the anthropogenic CO2 emitted each year is absorbed by the biosphere. In fact about 20% of the ACO2 in the atmosphere is shunted into the other reservoirs each year, and that rate of absorption is the same as it is for NCO2. That is because the residence time for both ACO2 and NCO2 is about five years. However, as has been pointed out to you, residence time is not what controls the rate of growth or decline of atmospheric concentrations, that is decided by the adjustment time. The residence time depends on the volume of the flux of CO2 out of the atmosphere (which is vast, hence the residence time is short). The rate of growth of atmospheric CO2 however also depends on the volume of the flux into the atmosphere. To be specific, the rate of increase is proportional to the difference between total emissions and total uptake. This difference is much smaller (about half anthropogenic emissions), hence the adjustment time is much longer. The thing you don't seem to understand is that the atmosphere exchanges vast quantities of CO2 with the oceans and terrestrial biosphere each year. However, this is an exchange, with natural emissions approximately balanced by natural uptake, so even though it make residence time very short, it has very little effect on atmospheric concentration. Our emissions have altered the balance by increasing the partial pressure of CO2 in the atmosphere, which increases uptake by the oceans (and it is plant food, so some extra goes into the terrestrial biosphere), and hence the natural environment has become a net carbon sink. That is why the observed rise is only about half anthropogenic emissions. Do the differential equations for a one-box model of the carbon cycle and you will find this is correct.
  10. DM and I differ in subtle ways in out terminology, but we are saying exactly the same thing. Just to be clear.. DMs "exchange" is what I would call equal and opposite gross fluxes between reservoirs. Gross fluxes are used to calculate residence time of a reservoir - for CO2 about 5 years. A residence time of 5 years implies that 1/5th or 20% of the atmospheric CO2 molecules passes into other reservoirs every year. That 20% is largely replaced by movement of CO2 into the atmosphere from other reservoirs. My "net exchange" is DMs "flux" -- i.e. net movement of material from one reservoir to another. This net movement between reservoirs is what matters for rate of change in the size of the atmospheric CO2 reservoir. The annual net movement of atmospheric CO2 into oceanic and terrestrial reservoirs are half the size of anthropogenic CO2 emissions. That's the atmospheric CO2 increases at only half the rate of anthorpgenic emissions. The bank account analogy is perfactly a propos here. If my income amounts to 20% of my balance per year and my costs amount to the same, I am not going to see an increase in my balance. If I get a new source of income that amounts to only 3% of my balance every year, but I only spend half of that new income, my balance will increase by 1.5% per year. If I lose that income and don't reduce my costs, my bank account will decline slowly as well. Its that simple. Come to think of it. My bank account looks too much like the C cycle for my liking.
    Response: [Dikran Marsupial] Yes, that is absolutely correct. The reason that the airborne fraction is approximately constant is because we are forcing an approximately first order dynamical system with an approximately exponential perturbation. The result is an approximately exponential increase in atmospheric CO2 with a time constant virtually the same as the perturbation, so if you divide input by output you get approximately a constant value. It is nothing to do with differential absorbtion rates, which as you correctly point out is about 20% for both natural and anthropogenic CO2.
  11. Stephen Baines, 5/13/11, 12:30 PM, You wrote, pointlessly, The fact that the atmosphere is not now in equilibrium has no bearing on this debate. That is a red herring. You quote me as if I had introduced something irrelevant. I agree, it IS a red hearing, which is exactly why I have no use for it, and why I responded to Dikran Marsupial's vacant charge that I confused residence time with adjustment time. Then you write, The residence time also has almost no bearing on how quickly the CO2 added to the atmosphere will be absorbed by the biosphere. IPCC provides the following formula: Turnover time (T) (also called global atmospheric lifetime) is the ratio of the mass M of a reservoir (e.g., a gaseous compound in the atmosphere) and the total rate of removal S from the reservoir: T = M / S. For each removal process, separate turnover times can be defined. In soil carbon biology, this is referred to as Mean Residence Time. AR4, Glossary, p. 948. (The remark about being Mean Residence Time in soil carbon biology is a litigator's half-truth, intended to give the impression that T is not the Mean Residence Time in all applicable fields.) You might recognize the formula as saying S = dM/dt and dM/dt = M/T. The solution is the exponential, so the reservoir mass, M = M_0*exp(-t/T). This is also the impulse response of the reservoir. So if you put in a slug, M, of ACO2 at t = 0, it will decay according to that formula. Now if you continuously input ACO2, the reservoir will accumulate ACO2 according to the convolution of the input function with the impulse response. The difference between the input function and the amount retained in the atmosphere is your amount that will be absorbed by the biosphere. The residence time, T, has everything to do with the amount absorbed by the biosphere. IPCC shows its estimate of the increase in ACO2 emissions in AR4, Figure 2.3, p. 138. Between 1981 and 2002, it increased at a best fit rate of 1.55%/yr. If we extrapolate that back to 1750, the start of the industrial era. the emissions were 0.15 GtC/yr in 1750, increasing to 10.98 GtC/yr in 2030, and the total emissions over that period is 705 GtC. The amount accumulated in the atmosphere asymptotically approaches 594 GtC (84.3% of the total) for a residence time of 350 years, 247 GtC (35.0%) for a residence time of 35 years, and 36.0 GtC (5.1%) for a residence time of 3.5 years. The last figure, which is the result from IPCC's formula and data, sans leaf water, but it doesn't put enough CO2 into the atmosphere. By never relying on the formula, IPCC gains a handle on ACO2 emissions. It can rationalize the residence time to put just enough CO2 in the atmosphere to match the bulge at MLO. Of course, IPCC doesn't actually rely on equations here. It just declares the bulge to be ACO2. This phony claim by IPCC gives its supporters fits. They stand on their heads to redefine terms or introduce new ones, and safe to say, never with citations. ACO2 does not accumulate in the atmosphere, and there isn't enough present to make AGW work. Pity. CO2 residence time is essential to systems science, and a misunderstood play thing for AGW climatologists. P.S. Re. your post on 5/14/11, 01:09 AM. You are correct enough that "there is nothing special about anthropogenic carbon." But that is my argument. Repeating it doesn't help your position. You need to bring that fact to the attention of IPCC and AGW believers. It is IPCC, not I, that treats nCO2 and ACO2 to substantially different physics. And I've given you all the proof.
  12. Stephen Baines, 5/14/11, 01:09 AM CO2 residence time How do you know that 'Anthropogenic' (notice how they use quotation marks) fluxes simply refer to the change in rates that has occurred because pCO2 in the atmosphere has increased and land use changes have occurred. Do you have a citation from IPCC or an IPCC reference? You seem to put a lot of stock in the fact that IPCC put anthropogenic in quotation marks for Figure 7.3. It also wrote "'natural' fluxes". What does that lead you to conclude? In another context, IPCC said, Collins et al. (2002) calculated indirect GWPs for 10 NMVOCs with a global three-dimensional Lagrangian chemistry-transport model. Impacts on tropospheric ozone, CH4 (through changes in OH) and CO2 have been considered, using either an ‘anthropogenic’ emission distribution or a ‘natural’ emission distribution depending on the main sources for each gas. AR4, ¶2.10.3.3 Non-methane Volatile Organic Compounds, p. 214. Here IPCC appears to employ quotation marks because the data are synthetic, drawn from calculated emission distributions. This is a likely reason for offsetting the same words in the caption to Figure 7.3. Between the TAR and AR4, IPCC uses the word anthropogenic 1,799 times (including indices, references, tables of contents), but only in these two instances is it offset quotation marks. Without using quotation marks, IPCC says, About 80% of anthropogenic CO2 emissions during the 1990s resulted from fossil fuel burning, with about 20% from land use change (primarily deforestation) (Table 7.1). Almost 45% of combined anthropogenic CO2 emissions (fossil fuel plus land use) have remained in the atmosphere. AR4, ¶7.3.1.2 Perturbations of the Natural Carbon Cycle from Human Activities, pp. 514-15. In case you might want to start relying on numbers, the first sentence supports the land use change of 1.6 GtC/yr out of a total ACO2 of 8 GtC/yr per Figure 7.3. Note that 45% of ACO2 has remained in the atmosphere. Why the restriction to ACO2? The chart has (8-4.6)/8 = 40% remaining in the atmosphere. Maybe the quotation marks account for the discrepancy. Meanwhile the chart has 0/191.2 = 0% of "'natural' flux" remaining in the atmosphere. You claim to the contrary, When pCO2 increased over preindustrial, there was an increase in net CO2 flux into the ocean. … There is nothing special about anthropogenic carbon. The IPCC graph does not imply in anyway that there is. Why didn't that increase in pCO2 affect both ACO2 and nCO2 since the dawn of the industrial era? Regardless of your rationale, that IPCC treats the flux of nCO2 quite differently than it does ACO2 is inescapable.
  13. FWIW, I practiced with "numbers" on the mac which I installed today. I took the MtC emissions for each year since 1751 from this table: http://cdiac.ornl.gov/ftp/ndp030/global.1751_2007.ems and used a starting amount of 597,000 MtC. I added the amount from the table at that link each year and subtracted the amount : (E3-597000)*EXP(-1*$I$2) where $I$2 is my lambda and E3 is that year's MtC. I picked a target year of 2008 and 818,000 MtC. I achieved the target with lambda of 4.25 which is a fairly steep decay. Finally, I'd like to convert that to a half life number (in years) but I'm not sure how.
  14. Dikran Marsupial, 5/14/11, 4:49 AM, CO2 residence You claim, In fact about 20% of the ACO2 in the atmosphere is shunted into the other reservoirs each year, and that rate of absorption is the same as it is for NCO2. Please supply a citation. You say, That is because the residence time for both ACO2 and NCO2 is about five years. However, as has been pointed out to you, residence time is not what controls the rate of growth or decline of atmospheric concentrations, that is decided by the adjustment time. (1) As pointed out to you on 5/13/11, 2:36 AM, the formula provides 1.51 years if leaf water is included, and 3.48 years otherwise. (2) The fact pointed out is false. (3) The actual definition of adjustment time has nothing directly to do atmospheric concentrations. I provided you the official IPCC definition of adjustment time on 5/13/11, 8:06 AM. You ignored it. It contradicts your unsupported claim. You say, The residence time depends on the volume of the flux of CO2 out of the atmosphere (which is vast, hence the residence time is short). The formula in the TAR and AR4 glossaries is T = M/S, where T is the Turnover Time, aka the Mean Residence Time. M is the volume in the equation, but it is the volume of the reservoir, not of the flux. S is the flux in the equation, but it is a rate not a volume. There is no volume of the flux. You say, The thing you don't seem to understand is that the atmosphere exchanges vast quantities of CO2 with the oceans and terrestrial biosphere each year. However, this is an exchange, with natural emissions approximately balanced by natural uptake, so even though it make residence time very short, it has very little effect on atmospheric concentration. I agree; I don't under gobbledygook. Natural emissions are exactly balanced by natural uptake, as modeled (incorrectly) by IPCC. (It's incorrect because natural emissions follow sea surface temperature, keeping the atmosphere perpetually out of balance as it responds to the long term waxing and waning of the Sun.) (1) The fact that it is in balance, i.e., that E_n = U_n does not make the residence time either short or long. (2) What does determine the residence time is [CO2_air]/(U_n + U_a). It is the ratio of the concentration in the reservoir to the uptake rate. (3) The residence time of each type of gas has a huge, proportional effect on its atmospheric concentration. See the details in my post of 5/14/11, 9:25 AM. On 5/13/11, 20:18 PM [sic], you correctly noted that I had in one place written E_a for U_a.
  15. Eric (skeptic), 5/14/11, 12:05 PM, CO2 residence Let r = S/M, the ratio of the uptake from the reservoir, S, in a period to the volume in the reservoir, M, at the start of the period. Mean Residence Time = M/S = 1/r in periods. Half-life = log(0.5)/log(1-r) in periods.
  16. drrocket - "Note that 45% of ACO2 has remained in the atmosphere." That is actually quite incorrect. An amount of CO2 equivalent to half the anthropogenic emissions has remained in the atmosphere. Not the individual molecules, but a sum total. This is because the natural sinks (as we don't act as a sink to any significant degree) have absorbed an excess amount of CO2 equivalent to 55% of our emissions. There is no difference to the sinks (especially in the ocean) between anthropogenic and natural CO2, aside from the slight plant preference for one isotope over another. Each CO2 molecule has about the same chance of being exchanged. It's just that the sinks don't match up to the sources, drrocket. By an amount equal to not quite half to what we emit.
  17. drocket, I don't understand why you can't get this. It's simple. You are confusing yourself. I also don't understand why [ - snip - ] have to debate every single niggling detail of climate science, as if climate scientists can't get the slightest thing right, and it's amazing that they even find their way to work every morning. I mean, debate climate sensitivity or cloud feedbacks or something. Debating this is beneath everyone here. Really, something like this should not be this hard. Go study some and stop wasting everybody's time with utter and complete nonsense. Hint #1: Study basic chemistry, diffusion, and rates of reaction, and then come back. Hint #2: Sometimes an ability to put things into numbers and equations translates into an inability to grasp the basic, underlying concepts.
  18. KR, 5/14/11, 14:50 PM [sic], CO2 residence In the quotation you attribute to me, you dropped the source, falsely making the quotation appear to be my words. Or, did you not realize that you were criticizing a quotation from IPCC? Then in your last ¶, you reinforce the misimpression. You should have written, It's just that the sinks don't match up to the sources, drrocket IPCC. Otherwise, we are in substantial agreement – so far.
    Response: [Dikran Marsupial] You appear to have misread KRs post, AFAICS he was not attributing anything to you, but directing the statement to you.
  19. drrocket@64 You have a bad case of Dunning-Kruger, there are aspects of the carbon cycle you are ingorant of, and your ego is getting in the way of you correcting this failing (calling an argument you don't understand 'gobbledygook' is a classic example of D-K in action). "Natural emissions are exactly balanced by natural uptake, as modeled (incorrectly) by IPCC." No, the models of the carbon cycle used by the IPCC do not have natural emissions exactly balanced by natural updake. If they did, the airborne fraction for their model would be 100% instead of 45%. "It's incorrect because natural emissions follow sea surface temperature, keeping the atmosphere perpetually out of balance as it responds to the long term waxing and waning of the Sun" One of the things you appear to be ignorant of is that the ocean uptake is also governed by the difference in partial pressure of CO2 between the atmosphere and the surface waters. This means that if atmospheric CO2 rises, the oceanic uptake increases. The increase in uptake due to increasing atmospheric CO2 exceeds the increase in emissions due to the modest rise in temperature, which is why the oceans are a net sink. This is carbon cycle 101 stuff. "(1) The fact that it is in balance, i.e., that E_n = U_n does not make the residence time either short or long. " It is not a fact that E_n = U_n, and I did not say it makes the residence time short or long. The residence time does not depend on E_n only on U_n. It is the adjustment time that depends on the difference between E_n and U_n. "(2) What does determine the residence time is [CO2_air]/(U_n + U_a). It is the ratio of the concentration in the reservoir to the uptake rate. " Yes, you know that, I know that and the IPCC knows that. However, where the you (and Essenhigh) differ from the IPCC and I is that we know that residence time is irrelevant to the discussion of the increase in atmospheric CO2, and it is tha adjustment time that matters. " The residence time of each type of gas has a huge, proportional effect on its atmospheric concentration." No, it doesn't as the residence time is dominated by an exchange of carbon between the atmosphere and oceans/biosphere that has no effect whatsoever on the atmospheric concentration. Right, if you are still reading at this point, here is a variation on the challenge. Explain how the natural environment can be a net source of CO2 into the atmosphere while the observed annual rise in atmospheric CO2 is less that anthropogenic emissions. If you can't answer that question, your position is untenable.
  20. drrocket, let's try going through this line by line. Forgetting for a moment about the mechanisms by whcih it takes place, would you agree that there is conservation of matter in the carbon cycle? i.e. dC = E_a + E_n - U_n i.e. the annual rise in atmospheric CO2 is the difference between total emissions (anthropogenic and natural) and total uptake (assuming for simplicity that anthropogenic uptake is effectively zero - we are not achieving significant carbon sequestration at the current time). I would hope you do agree with this, as it is basically just saying that any CO2 (from any source) that is not taken up by the oceans/terrestrial biosphere remains in the atmosphere, which seems completely uncontraversial as far as I can see!
  21. drrocket, I'm not sure I determine the total uptake from my simple spreadsheet. I have the net flows for each year and that would give a Mean Residence Time of 1/(3400/814000) or 255 years. The 814000 is the reservoir for 2007 and 3400 is the net loss from the reservoir in 2007 based on my hypothetical exponential decay with lambda of 4.25 But I was able to fill the spreadsheet with more rows and turn off the ACO2 starting in 2008. At that point the "extra" CO2 in the reservoir decays from 814000 to 708000 in 58 years. However, this is likely a high estimate because my lambda is constant in my spreadsheet from 1750 to present and in reality lambda increases as the reservoir increases. Englebeen thinks the half life is about 40 years. I posted my spreadsheet on my (brand new) online iwork account if anyone wants to look at it. It should be publicly accessible here: http://public.iwork.com/document/?a=p1415598010&d=CO2growth.numbers
    Response: [Dikran Marsupial] For the calculation of the residence time, it is the mass of the reservoir divided by the total flux out of the reservoir, rather than the net flux. You should get an answer of about four years. The use of the net flux gives you something more like the adjustment time, although that can't be calculated meaningfully without doing a differential equation or two.
  22. Thanks, I knew that 255 years was wildly high, so I knew my flux was way too low. I have no way of calculating total flux in my very simple approach since I am only using total ACO2 and total atmospheric reservoir and a hypothetical exponential decay of the ACO2 (total minus preindustrial CO2).
  23. Dikran Marsupial, 5/15/11, 02:09 AM, CO2 residence 1. On the post above, 23:19 PM, you inserted this: Response: [Dikran Marsupial] You appear to have misread KRs post, AFAICS he was not attributing anything to you, but directing the statement to you. Not at all. KR (1) addressed me, followed by (2) "colon", then (3) an exact quotation, but (4) omitted the source. To confirm that this was KR's misattribution, I pointed out that his final instruction was directed to me instead of the source. Of course, the source of this misinformation was the IPCC. 2. You wrote incorrectly, No, the models of the carbon cycle used by the IPCC do not have natural emissions exactly balanced by natural uptake. If they did, the airborne fraction for their model would be 100% instead of 45%. 2.1 The models used by IPCC in AR4 Figure 7.3 have the natural flux between air and the surface exactly balanced. You may not like it, but its true. If you want to argue that IPCC is inconsistent, I would agree, but that is a different matter. This fact of natural balance is reinforced by the IPCC text, AR4 ¶7.3.1.2, cited for you, and which you also ignore. That passage says that the flux is out of balance expressly with respect to ACO2, implying that the natural is in balance, confirmed by the figure. 2.2 You got the airborne fraction wrong, too, and twice. Here's what airborne fraction means: The relationship between increases in atmospheric CO2 mixing ratios and emissions has been tracked using a scaling factor known as the apparent ‘airborne fraction’, defined as the ratio of the annual increase in atmospheric CO2 to the CO2 emissions from annual fossil fuel and cement manufacture combined (Keeling et al., 1995). AR4, ¶2.3.1 Atmospheric Carbon Dioxide, p. 139. 2.2.1 Airborne fraction has nothing to do with the natural flux. 2.2.2 If the airborne fraction were similarly defined for nCO2, then it would be 0%, not 100%. 3. You repeat a minor IPCC error when you write, One of the things you appear to be ignorant of is that the ocean uptake is also governed by the difference in partial pressure of CO2 between the atmosphere and the surface waters. 3.1 The uptake of a gas in liquid is determined by the partial pressure of the gas above liquid. William Henry, 1803. IPCC does not bother to use Henry's Law because it is incompatible with its claim that the surface readily absorbs nCO2 but buffers against ACO2. This is also confirmed by IPCC's attempt to rehabilitate the failed Revelle Buffer Factor. 3.2 A dissolved gas has no partial pressure. Sometimes investigators will deem it to exist, but in doing so they mean the partial pressure of the gas that would exist above the liquid at equilibrium. The beautiful Takahashi diagram (ON WHY CO2 IS KNOWN NOT TO ACCUMULATE IN THE ATMOSPHERE, etc., Figure 1A, AR4 Figure 7.8, p. 523, modified) is based on the fictional partial pressure of dissolved CO2. This may account for the fact that the Takahashi cells have to be recalibrated to make his results consistent with the fluxes in AR4 Figure 7.3. 4. You write incorrectly, The increase in uptake due to increasing atmospheric CO2 exceeds the increase in emissions due to the modest rise in temperature, which is why the oceans are a net sink. This is carbon cycle 101 stuff. This little gem of ambiguity as to what is due to the modest rise in temperature is (a) preposterous on the one hand or (b) woefully uninformed on the other. (a) Your writing could mean that the increase in emissions is due to temperature. But that's just too silly. (Isn't it?) (b) Water does not increase its CO2 uptake with increasing temperature. CO2 uptake increases with decreasing temperature. Where exactly did you take carbon cycle 101? I want to be sure and steer people away from that institute. 5. Even after being instructed that you are using the term adjustment time you continue with the practice, and with no references. You are using it incorrectly with respect to the IPCC definition. See my posts above, 5/13/11, 8:06 AM; 5/14/11, 12:48 PM. 6. You insist wrongly that It is not a fact that E_n =U_n … . E_n = 190.2 GtC/yr. U_n = 190.2. AR4, Figure 7.3, p. 515. Thus, don't you see, E_n = U_n, according to IPCC. You don't like it. I don't like it. But it's undeniably the IPCC model. 7. You misleadingly write with respect to the Mean Residence Time = M/S that IPCC knows that. Of course IPCC knows that. It's right out of its Third and Fourth Glossaries. The problem is that in the main body of those Reports, IPCC (a) never uses its own formula and (b) uses far different values for residence time, including declaring that it can't be defined, and then defining it with a different, physically impossible formula. You claim that residence time has not effect on the accumulation of CO2 in the atmosphere. All the while, IPCC goes to great and clumsy lengths to increase the residence time in order for ACO2 to accumulate in the atmosphere, so to cause AGW. If IPCC was a physician, it would practice touching up x-rays. 8. You insist incorrectly that However, where the you (and Essenhigh) differ from the IPCC and I is that we know that residence time is irrelevant to the discussion of the increase in atmospheric CO2, and it is tha [sic] adjustment time that matters. 8.1 Adjustment time is the time that the climate requires to come to equilibrium. It is of no use in determining the amount of CO2 accumulation. 8.2 I spelled out in detail the effects of various residence times on the accumulation of CO2. 5/14/11, 9:25 AM. You have completely ignored it to make a naked counter claim. I buy you books and buy you books and all you do is eat the covers. 9. You state incorrectly, [T]he residence time is dominated by an exchange of carbon between the atmosphere and oceans/biosphere that has no effect whatsoever on the atmospheric concentration. 9.1 You repeat your lack of appreciation for residence time. See 8.2, above. 9.2 The residence time is not dominated by anything. It is determined by the mass in the reservoir, M, divided by the rate of loss from that reservoir, S. It is not affected by replenishment, i.e., emissions. In that regard, perhaps I confused you by writing that S = dM/dt without explicitly saying that any part added to M is held constant. Only the loss function, S, not the emissions, has anything to do with residence time. 10. You challenged this: Explain how the natural environment can be a net source of CO2 into the atmosphere while the observed annual rise in atmospheric CO2 is less [than] anthropogenic emissions. If you can't answer that question, your position is untenable. 10.1 The natural environment is a net, lagging source of CO2 while the climate is warming, and a net lagging sink for CO2 when it is cooling. Statistically, the climate is always in one state or the other. This is known from the Vostok record. It is the background for ACO2 additions. 10.2 The observed annual rise in atmospheric CO2 is apparently valid for MLO, although that record as published is reconstituted and quite dubious in any detail. Moreover, that record is (1) regional, (2) located in the intense plume of the massive oceanic outgassing, and (3) subject to slow modulation as the plume wanders. 10.3 Current annual emissions into the atmosphere are those due to contemporary global warming, multiplied roughly by, say, 1.03 to 1.05 to account for the added ACO2 emissions. 10.4 The accumulation of CO2 in the atmosphere is (1) the ramp in emissions per 10.3 convolved with (2) the impulse function represented by the CO2 residence time. The ratio of the integral of the ramp, equivalent to MRT = ∞, and that for an MRT = 3.5 years is 5.1%. See my post above, 5/14/11, 9:25 AM. 10.5 According to this model, and combining 10.3 and 10.4, the global CO2 concentration in the atmosphere is accumulating 5.1% of the total outgassed due to warming plus ACO2. The contribution of ACO2 is 5.1% of a figure between 3% and 5%, or 0.2 to 0.3% of the total emissions during warming. While this is well buried in the noise of atmospheric measurements and global estimations, the model explains why the observed annual rise in atmospheric CO2 is less than anthropogenic emissions. 10.6 What is quite untenable is AGW. Of course, getting the CO2 and surface temperature right does not solve all the climate matters. It just settles that AGW is a failed conjecture.
  24. drrocket wrote: "2.1 The models used by IPCC in AR4 Figure 7.3 have the natural flux between air and the surface exactly balanced. You may not like it, but its true." your first substantive point is demonstrably incorrect, here is figure 7.3 (click the image to go to the source): The natural uptake components are: 0.2 weathering (black arrow) 120 GPP (black arrow) 2.6 land sink (red arrow signifying a post-industrial change) 70 flux into surface ocean (black arrow) 22.2 red arrow representing post-industrial change in uptake by surface ocean total natural uptake 215 GtC per year The natural emissions are comprised of 119.6 respiration (black arrow) 70.6 flux from the surface ocean (black arrow) 20 post industrial change in emissions from surface ocean (red arrow) total natural emissions 210.2 GtC per year. Clearly the "natural flux between air and the surface" are not "exactly balanced" according to the IPCC as you claim. In fact the diagram asserts the natural environment to be a net carbon sink, with uptake exceeding emissions by 4.8 GtC per year. "You may not like it, but its true." Now lets compare that with anthropogenic emissions (labelled "fossil fuels" 6.4 GtC/year and "land use change" 1.6 GtC/year), a total of 8 GtC/year. This exceeds the natural net sink, which is why atmospheric CO2 is increasing. So given your first substantive point (rather than mere pedantic quibbling over English usage) was utterly wrong, there seems little point in discussing the gish gallop further unless you are able to admit you were wrong on that very first point.
  25. drrocket, you say "10.1 The natural environment is a net, lagging source of CO2 while the climate is warming, and a net lagging sink for CO2 when it is cooling. Statistically, the climate is always in one state or the other. This is known from the Vostok record. It is the background for ACO2 additions." The Vostok record http://en.wikipedia.org/wiki/File:Co2-temperature-plot.svg shows about a 100 ppm change in CO2 for a 10 C change in temperature. Our current temperature rise from the LIA (which I personally consider to be mostly natural) is less than 1C That corresponds to a 10 ppm increase in CO2. The other 90 ppm increase is man made. IOW, without manmade CO2 we would have seen a 10 ppm rise. With manmade CO2 we have seen over a 100 ppm rise.
  26. Dikran Marsupial, 5/15/11, 02:32 AM, CO2 residence 1. Even IPCC, which capitalizes on the sequestration conjecture, would not set U_a = 0. With its full sequestration bottleneck in effect, IPCC makes U_a = 0.55 E_a. 2. Sequestration does not operate by the biological pumps being connected to the atmosphere as IPCC shows in its carbon pumps. AR4 Figure 7.10, The biological pumps of sequestration must draw from ionized CO2, not molecular CO2 in the air. Nor can pumps operate as IPCC expresses in its equation for the Bern Carbon cycle. AR4, Table 2.14, p. 213. See these reproduced and discussed discussed here as Figure 10 and Equation 30. The equation is a model in which each of the pumps has its own, independent reservoir. The solubility pump (IPCC calls the "solution pump") has access 18.6% of the atmosphere, the organic carbon pump has access to a separate 33.8% of the atmosphere, and the CaCO3 counter pump has access to 25.9% of the atmosphere, leaving 21.7% of atmosphere not connected to any pump. The ocean is not well-represented by that configuration. The solubility pump has access to 100% of the atmosphere, a volume of the dissolved CO2 greater than that at equilibrium remains in molecular form, or nearly so, to satisfy Henry's Law and to be ionized to feed the two biological pumps. Established physics cannot be relied on or ignored by replacing physical terms with new definitions peculiar to climatology. That requires special treatment for novel validation. Equilibrium cannot replace steady state to extend the validity of the Second Law of Thermodynamics. Replacing thermodynamic equilibrium with dynamic equilibrium invalidates equilibrium chemistry. Replacing residence time with a unique adjustment time invalidates the principles of math and physics that govern even a simple leaking pail.
  27. Eric (skeptic), 5/15/11, 21:10 PM, CO2 residence Where I said twice in 10.1 that the natural environment was a lagging source, I should have said, of course, that is a leading source. Sorry. The Vostok record, being from ice cores, is a heavily low-pass filtered version of what we measure with modern CO2 instrumentation, and it has a prolonged sample interval. The integration time in an ice core reportedly is as large as a millennium or two, compared to at most one minute in the manual mode for modern measurements. The sample time for Vostok is about 1,300 years compared to a minute or less for modern instrumentation. The confidence level for the Vostok record to detect an event like the half century surge at MLO is not the usual 90% or 95%; it is about 3%. Alternatively. if Vostok were to have included an MLO-like surge, it's standard deviation would have been attenuated by the square root of, say, 1000 years divided by 1 minute (5.26*10^8), or 23,000. The Vostok record is not directly comparable to, say, the MLO record. If you want to compare Vostok and MLO either in CO2 increase or the rate of CO2 per ºC, you want first to filter the MLO record with a low pass filter with a time constant between 30 and 2000 years. What do you get then?
  28. drrocket wrote: "1. Even IPCC, which capitalizes on the sequestration conjecture, would not set U_a = 0. With its full sequestration bottleneck in effect, IPCC makes U_a = 0.55 E_a." No, U_a does not represent the uptake of anthropogenically generated CO2 by the environment, it represents the removal of CO2 from the atmosphere due to human activities, i.e. it represents artificial carbon sequestration. The IPCC clearly would not say that we annually sequester (e.g. via carbon capture schemes) 55% of the carbon we emit. We annually sequester a fraction of a percent of out emissions, such a small amount that it isn't currently worth discussing. Note that I have already pointed out your misunderstanding in this post. The fact that you are continuing in the misunderstanding suggests you are not reading the responses to your arguments with sufficient diligence. To be clear, anything with a _n subscript represents fluxes into or out of the atmosphere as part of the natural carbon cycle, anything with a _a subscript represents anthropogenic emissions (fossil fuel use and land use changes) or artificial sequestration of carbon (e.g. burying carbon in mines or pumping it into aquifers etc, which is to all intents and purposes effectively zero). Your second point is irrelevant as it is due to your misunderstanding of what U_a represents. The oceanic solubility pump and organic carbon pumps are described by U_n, not U_a.
  29. Dikran Marsupial, 5/15/11, 21:08 PM, CO2 residence IPCC uses Figure 7.3 to convey to its target audience, the Policymakers, how it models climate. IPCC (1) computes the response of the climate to the natural cycles in balance, (2) computes separately the response to anthropogenic unbalanced forcings, and (3) adds the two. Aside: This additive treatment, coupled with IPCC's admission that climate as modeled is non-linear, violates a principle of system science: additive applies only to linear systems. The erroneous addition leads to nonsense. Regardless, had IPCC's strange model only resulted in a non-trivial prediction subsequently validated, it would have been scientifically acceptable. It didn't, and it isn't. IPCC uses its own version of system science, not even aware of this traditional and highly relevant system modeling specialty. James Hansen introduced climate feedback explicitly from system science (Bode) in 1984. By the time it got into IPCC Reports and models, it bore no resemblance to its definition in science or its use by Hansen. Once a signal internal to a system that alters the system inputs, IPCC turned it into correlation between system parameters, and, at other times, a computer parameter calculated at run time. Natural fluxes used in IPCC's model, IPCC shows in black in the figure, and anthropogenic fluxes in red. You may not change those assignments and have any claim to being rational or honest. You have arbitrarily and intentionally juggled the data, changing IPCC's message just so you could say I was incorrect. To be specific, in your list you have erroneously added four black items to two red ones. Previously, you demonstrated a willingness to replace residence time with a phony adjustment time. You have also denied the physics of the leaking pail. I suspect that you would be among those who change balance to equilibrium, and thermodynamic equilibrium to dynamic equilibrium, balance or steady state. Or change feedback signals into correlations. When an AGW supporter uses a word, it means just what he chooses it to mean, nothing more, nothing less. All this is not my pedantism; it is your equivocation. It may be consistent with IPCC Reports, its climatologists, and other AGW believers, but that's the kind of support you want to avoid. Equivocation is not just inconsistent with science, it is intolerable. Science is an exacting discipline; AGW climatology is not. Equivocation is illogical and irrational. It violates my candidate for the first axiom of science: its domain is in the rational. If you just do the basic accounting honestly, putting numbers in their proper columns, you will validate my posts on the subject.
  30. DrRocket wrote: "Natural fluxes used in IPCC's model, IPCC shows in black in the figure, and anthropogenic fluxes in red. You may not change those assignments and have any claim to being rational or honest." You obviously didn't read the caption, the black arrows represent the "pre-industrial ‘natural’ fluxes in black". In the section below the figure, it says "In Figure 7.3 the natural or unperturbed exchanges (estimated to be those prior to 1750) among oceans, atmosphere and land are shown by the black arrows." The red arrows show the anthropogenically induced post-industrial changes in those natural fluxes. These changes are partly due to increased temperature and partly due to increased atmospheric CO2. For example consider the red arrow labelled "land sink" - it represents the increase in GPP due to the additional "plant food" (CO2) in the atmosphere. Of course prior to 1750 the natural fluxes were in close balance, at that time atmospheric CO2 was essentially constant and anthropogenic emissions were negligible. That doesn't mean natural fluxes are exactly balanced now - nobody is claiming they are. The direct anthropogenic fluxes are the two labelled "fossil fuel" and "land use change". The other red arrows represent feedback responses of the natural carbon cycle to the anthropogenic emissions. That is why they are described as "anthropogenic", note the use of quotes in "and ‘anthropogenic’ fluxes in red".
  31. drrocket - I quoted what I saw, which appeared to be your words; my mistake. Rereading your post you were re-stating an earlier IPCC statement. However, what I was responding to was your apparent misunderstandings on CO2 sources/sinks and the mass balance issues. Preindustrially CO2 exchanges were in rough balance between sources and sinks. We've added ~29GT/year to the sources, and we're observing an atmospheric increase equal to ~13-14GT/year. Natural carbon sinks, primarily the ocean, are absorbing more than half of the excess, but we're still seeing rising atmospheric CO2. Without our CO2 contribution, given the observed rates, atmospheric levels would be declining at ~2ppm/year. Hence we are responsible for the rise in CO2. I'm also under the distinct impression that you are overemphasizing residence times for individual molecules of CO2 versus adjustment times for total concentrations - our primary concern is the adjustment time, which is hundreds of years at a minimum. Finally, you've made a great deal of the isotopic differences in carbon. Those isotopic differences make it possible to determine attribution of the CO2 present (source determination), but don't affect carbon sinks. Nobody claims (as you stated) that "Natural CO2 is far more soluble than anthropogenic CO2" - that's a complete strawman. You've made a number of strawman arguments, much discussion of detail while overlooking the big picture, all for what to me is a rather unclear claim that our CO2 emissions are not significant. I would disagree.
  32. Dikran Marsupial, 5/16/11, 2:28 AM, CO2 residence You took what IPCC wrote out of context to misconstrue it. Here's the full paragraph, with your extraction underscored: In Figure 7.3 the natural or unperturbed exchanges (estimated to be those prior to 1750) among oceans, atmosphere and land are shown by the black arrows. The gross natural fluxes between the terrestrial biosphere and the atmosphere and between the oceans and the atmosphere are (circa 1995) about 120 and 90 GtC yr^–1, respectively. Just under 1 GtC yr^–1 of carbon is transported from the land to the oceans via rivers either dissolved or as suspended particles (e.g., Richey, 2004). While these fluxes vary from year to year, they are approximately in balance when averaged over longer time periods. Additional small natural fluxes that are important on longer geological time scales include conversion of labile organic matter from terrestrial plants into inert organic carbon in soils, rock weathering and sediment accumulation (‘reverse weathering’), and release from volcanic activity. The net fluxes in the 10 kyr prior to 1750, when averaged over decades or longer, are assumed to have been less than about 0.1 GtC yr^–1. For more background on the carbon cycle, see Prentice et al. (2001), Field and Raupach (2004) and Sarmiento and Gruber (2006). Bold added, AR4, ¶7.2.1.1 The Natural Carbon Cycle, p. 514. 1. The natural flux estimates are updated as of 1995. 2. The 120 GtC/yr, above, equals GPP on Figure 7.3, but the gross natural flux of 90 GtC/yr is awkwardly not confirmed there. IPCC seems to have arbitrarily and pointlessly converted ± 20 GtC/yr of natural air-sea flux into ACO2. If you wanted to change the red-black assignment, I would have no objection to you converting this ± 20 GtC back from red to black. That would be harmless and would not change the natural balance, nor for that matter, the absolute anthropogenic imbalance. Best of all, that conversion would support the 90 GtC/yr figure from ¶7.2.1.1. 3. You might misread "these fluxes" in the fourth sentence, but, being plural, it is a reference to the gross natural fluxes in the second sentence plus (reasonably and without loss of generality) the Richey flux. This assignment follows since the Richey flux immediately preceding in the third sentence is not only inconsequential, but singular and not plural, confirmed in Figure 7.3 at 0.8 GtC/yr. 4. The gross natural fluxes are approximately in balance when averaged over longer time periods than year to year. 5. Because natural fluxes are approximately in balance over periods of longer than one year, IPCC justifiably modeled them as in balance going back to 1750, the nominal start of the industrial era. 6. Therefore the natural fluxes in Figure 7.3 are as of 1750, revised in 1995, and are still valid "as of end 1994" (caption, Figure 7.3). The natural fluxes are not, as you suggest, just preindustrial values, but fluxes for all seasons. 7. IPCC used color to distinguish between natural and anthropogenic CO2 and CO2 fluxes, and not, as you imagine, to distinguish between 1750 and modern CO2. Figure 7.3 is not an illustration of carbon cycle change during the industrial era. It is a diagram to teach Policymakers how IPCC models climate.
  33. drrocket wrote: "2. The 120 GtC/yr, above, equals GPP on Figure 7.3, but the gross natural flux of 90 GtC/yr is awkwardly not confirmed there." No, actually the figure does confirm the 90GtC/yr figure, add the 70GtC/yr pre-industrial flux into the surface oceans and the 22 GtC/yr post-industrial change, you get something "about 90 GtC/yr" "IPCC seems to have arbitrarily and pointlessly converted ± 20 GtC/yr of natural air-sea flux into ACO2." Yes, it would indeed be arbitrary and pointless. For most people that would be an indication that perhaps that is not what the IPCC has done and that perhaps they had misinterpreted something somewhere. As it happens it is not what they have done. "7. IPCC used color to distinguish between natural and anthropogenic CO2 and CO2 fluxes, and not, as you imagine, to distinguish between 1750 and modern CO2" My interpretation is consistent with the caption of the figure that explicitly states the black arrows represent the pre-industrial natural fluxes. "The global carbon cycle for the 1990s, showing the main annual fluxes in GtC yr–1: pre-industrial ‘natural’ fluxes in black" Your interpretation is inconsistent with the figure caption. That suggests to me that your interpretation is incorrect. My interpretation also gives figures for the 1995 fluxes that are consistent with those given in the papers referenced by the IPCC. Your doesn't. Again that suggests my interpretation is correct and yours is incorrect. However, it is clearly pointless discussing this any further, as you appear to know better than the IPCC and more than virtually all of the skeptic climatologists, of whom only Segalstad appears to believe the rise in CO2 is not anthropogenic. That should tell you something.
  34. O.K. Drrocket, lets try and make some progress and try again to go through this step by step. Conservation of mass suggests that any carbon emitted into the atmosphere that isn't taken up by the environment will stay in the atmosphere and cause atmospheric concentrations to increase. More specifically dC = E_a + E_n - U_a - U_n where: dC is the annual change in atmospheric CO2 in GtC/yr E_a is anthropogenic CO2 emissions, from land use changes and fossil fuel use U_a is anthropogenic uptake. This is not the amount of anthropogenic CO2 removed from the atmosphere each year. It is the amount of CO2 (from whatever source) removed from the atmosphere as a result of human activity. This means things like carbon capture and storage. Please pay particular attention to that point as you have already misinterpreted it twice. U_a is effectively 0GtC/yr. Our efforts at carbon capture and storage so far have been negligible compared with our emissions. E_n is natural emissions from the carbon cycle, in other words respiration, volcanic emissions, emissions from the surface ocean. U_n is natural uptake as part of the natural carbon cycle, in other words CO2 removed from the atmosphere as a results of chemical weathering, gross primary production, and absorption by the surface ocean (organic pump + solubility pump). Now please, no long rambling list of points, just give a direct answer do you agree with the carbon mass balance equation I have given in this post?
  35. Dikran Marsupial, 5/16/11, 6:13 AM, CO2 residence No one but you, now, said "about 90 GtC/yr", and about 90 does not mean 90. What you can support off Figure 7.3 is 92.2. That's the sum of 70 nCO2 plus an arbitrary 20 deduced to be ACO2 formerly nCO2, plus a critically important 2.2 ACO2. You can't just round off these numbers because that scraps a critical 27.5% of the total ACO2 flux. My fluxes are fully consistent with IPCC's fluxes. I do not rely on competing data sets, competing means of data reduction, or competing climate models, except to fill an IPCC void. I rely on nothing to contradict IPCC but the following: ( -Long rambling list of points snipped- ) ( -Long rambling discourse on ethics snipped- ). ( -Allegations of impropriety snipped- ). ( -Inflammatory snipped- ).
    Response:

    [DB] Please follow Dikran's lead; a better compliance with the Comments Policy is also requested.  Gish Gallop's normally get deleted en toto.

  36. Dikran Marsupial, 5/16/11, 6:23 AM, CO2 residence OK. Good approach. Answer: No. I disagree with your definition and evaluation of U_a. U_a are those particular molecules of ACO2, whether from fossil fuel combustion or land use, that end up in the surface reservoirs per year. I agree that man's sequestration of CO2 is negligible, limited, for example, to the manufacture of dry ice and tankage of CO2. So we don't have to worry about the apportionment of that sequestered CO2 between ACO2 and nCO2. But U_a must include the processes implied in Figure 7.3, i.e., the land-sink and dissolution in the surface waters. It wouldn't matter that U_a is inferred, and not directly measurable. That's true of all thermodynamic macroparameters, and we still deal with Global Average Surface Temperature and Global Average Albedos. Your move.
  37. drrocket - The appropriate term for your last post with a large list of items is a Gish Gallop; a long list of untruths, misconceptions, and errors. I will not attempt to answer each of these, but I will note that if you look at the Most Used Skeptic Arguments list on the upper left, you will find that most of these items have been addressed in the appropriate threads.
  38. drrocket - Why are you referring to particular molecules of anthropogenic CO2 in that equation, when Dikran specifically defined it as the total CO2 of whatever origin sequestered by mankind? If you insist on such a term, you will be required to add an additional term for natural origin CO2 also sequestered, or the equation will not contain all the sums. And Dikran has already done that by using a single term.
  39. drrocket... "Your move." So are you implying that this is just a chess game to you and not a rational discussion of the data and its meaning? Perhaps that is why you never seem to address the nub of the question. I still don't see how you intend to explain the persistent post industrial increase in CO2 with a natural net source given that... 1. The increase in atmospheric CO2 is less than predicted if all CO2 released by human activities remained in the atmosphere. 2. The change in stable isotopic composition of that CO2 indicates a source that is plant matter in origin. 3. The reduction in atmospheric O2 and the acidification of the ocean indicates that the ocean can't be the source and is instead a sink. 4. The change in terrestrial pools hasn't been nearly large enough to explain the increase in atmospheric CO2 5. The changes to terrestrial pools that have occured are due to human activities anyway.
  40. drrocket wrote: "Answer: No. I disagree with your definition and evaluation of U_a ... U_a are those particular molecules of ACO2, whether from fossil fuel combustion or land use, that end up in the surface reservoirs per year." Sorry drrocket, you are just being absurd now. I set out the mass balance equation and defined exactly what the terms mean. The question is, do you agree with the mass balance equation with the terms having the meanings I defined. If you do not, your position is absurd as it means that you don't agree that the annual increase in CO2 is the difference between total emissions (E_a + E_n) and total uptake (U_a + U_n which is approximately just U_n as U_a is essentially zero). Which is blindingly obvious to anyone capable of balancing a bank account. I suspect your attempt to change the meanings of the terms is just an attempt to avoid properly engaging in a line of discussion that will rapidly prove you wrong. It happens a lot in discussions with "skeptics". So, give a direct answer the question as posed and prove that you are not just trying to evade a line of discussion that will prove you wrong.
  41. drrocket (#77) you said "...you want first to filter the MLO record with a low pass filter with a time constant between 30 and 2000 years. What do you get then?" My concluding sentence in #75 would still stand (any excess over 10 ppm is man-made since the ice core change is about 10 ppm per degree C).
  42. I noticed this thread was referenced in the new "CO2 rising faster than PETM" thread. I wrote a spreadsheet that I just made publicly accessible (forgot to do that above). I used the published figures for CO2 added the atmosphere 1750-2008. Then I assumed an expoential decay. Nature absorbs about 1/2 of our added amount each year and since that is a consistent result year after year, an exponential decay back to preindustrial is a reasonable assumption. Based on the rise to 2008, the lambda is 4.25 (I also assume lambda is constant when it seems likely to rise with CO2 concentration). The half life of CO2 (time to return 1/2 way back to preindustrial) is 48 years. An argument that the "lifetime" of CO2 is 500 years or more is ill-defined and somewhat spurious. Yes, it would take that long to get all the way back to preindustrial, but getting half way back in 50 years is more meaningful. The document link is here: http://public.iwork.com/document/?a=p1415598010&d=CO2growth.numbers
  43. Eric (skeptic) The constant airborne fraction (45%) is essentially due to the fact that anthropogenic emissions are rising approximately exponentially. This result is easily reproduced by a one-box model of the carbon cycle (I am working on an article on this topic). That means if anthropogenic emissions are cut then the airborne fraction will be no longer constant. IIRC a simple one-box model of the carbon cycle gives an adjustment of about 74 years once you take that into account. There is nothing spurious about the 500+ year time scale. The carbon cycle can only be approximated very roughly by simple models such as yours. There are other reasonably well understood physical reasons (e.g. slow transfer of carbon between the surface and deep ocean) that make the simple model give unrealistically low estimates. If you want to look more deeply into these issues, I can recommend David Archer's primer on the carbon cycle, reviewed here However, your calculation is still much more accurate that Essenhigh's, as you obviously understand the difference between residence time and adjustment time. Also, CO2 levels falling about halfway back to pre-indiustrial levels in about 50 years is pretty much the mainstream view (posted by Daniel earlier in the thread)
  44. Thanks for the feedback. Yes, I understand impulse response times from engineering, but in engineering one does not generally black box the system being studied and just measure current and voltage. However the CO2 system should be treatable as a passive system to a point (extreme warming may turn it into an active system)
  45. Eric (skeptic) An engineer (I started out as an electronic engineer myself) ought to approve of the kind of models used in carbon cycle modelling (lots of differential equations). They are really "white box" models rather than "black box". They are called box models only because each carbon reservoir is modelled as a box with fluxes between boxes defined by the known physics. The "one box" I mentioned earlier is the simplest, with just one box representing the atmosphere, but to get a more realistic estimate of the adjustment time you need to model the other reservoirs (and their feedbacks) in detail (which leads to the long tail on the adjustment). Fascinating subject.
  46. michael, yes my spreadsheet is completely academic since I stopped CO2 in 2008 (I only had CO2 data through 2007) and we are current increasing worldwide, not stopping. Yes, I will take your suggestion and redo it with a somewhat plausible scenario and a BAU for comparison. The back of envelope calculation that supports my estimate is this: the environment is said to absorb 1/2 of our new CO2 each year. But it does not and can not possibly do that. Instead it absorbs about 2% of our total remaining excess over preindustrial (818,000-597,000). Even that is very oversimplified. If it were linear it would be removed in 100 years, or half in 50 years. It clearly is not for the reasons you point out. I would add that warming since the end of the LIA would have increased CO2 by 5-10 ppm had man done nothing at all. But I think an exponential decay to preindustrial is a reasonable estimate until we have more evidence for permafrost melting, etc (those are extremely slow processes).
  47. Eric (skeptic) @96, what the environment does is restore equilibrium between the partial pressure of CO2 in the atmosphere and the partial pressure of CO2 in the upper layer of the ocean. That is a rapid process, sufficiently rapid that even temperature fluctuations of 0.2 degrees C globally averaged can significantly affect the rate of absorption. That would not be the case if the surface and atmosphere where far from equilibrium. Consequently, the idea that the environment absorbs ~50% of annual emissions is much closer to the truth than that it absorbs 2% of the difference between current and pre-industrial CO2 levels. I can make the same point from a different direction. The fact is that ~50% of CO2 emissions have been absorbed annually since the industrial revolution. The rate of absorption is a function of the level of disequilibrium. Given that the rate of absorption has scaled with annual emissions rather than with cumulative emissions since 1850, it follows that the level of disequilibrium correlates with annual emissions rather than cumulative emissions. From that it follows that equilibrium is reached in a time scale close to one year. In the long term, CO2 levels will reduce despite this, because partial pressures of CO2 in the deep ocean and surface will equalize, gradually drawing down atmospheric CO2 to between 25% and 30% above peak values. After that the CO2 is only drawn down by geological processes, ie, over thousands of years. So, to conclude, your spreadsheet is based on a clearly false assumption. Again I refer you to Archer 2008. Or perhaps you will be content with Archer's rule of thumb (now considered optimistic), that CO2 will reduce to 25% increase over pre-industrial levels over a century, and that the remainder is there forever on human time scales. (I refer you to the charts posted by Dikran Marsupial @23.)
  48. Thanks Tom for explaining the rapid equilibrium with the upper ocean layer. If we posed the hypothetical question, what if mankind doubled or halved his contribution from one year to the next, would the upper layer of the ocean still absorb roughly 50%? Fortunately we can answer that question since nature performs this experiment every year. In the NH fall, the biosphere injects about 7 Pg net C into the atmosphere from (I added the NH amounts in table 3 in Randerson et al.: Trends in Seasonal Cycle of Atmospheric CO2 in Global Biogeochemical Cycles, vol. 11, no. 4, pages 535-560, December 1997). These estimates come from measurements of CO2 released and absorbed by various forest types times their area so are mainly empirical data. The comparable empirical data are the 750 Pg C in the atmosphere, the 390 ppm total and the 7 ppm annual cycle (peak to peak or 3.5 trough to peak). That works out to 6.75 Pg of fluctuation versus 7 Pg from the biosphere (net). There are some caveats, the oceans in the SH have a somewhat complementary cycle when they warm in the NH winter and consequently absorb less CO2 a bit after the the NH biosphere is releasing its annually stored CO2. Irregardless, it is clear that comparing the 6.75 to the 7 means that the top layer ocean in general (although mostly NH) absorbs very little of the CO2 released by the biosphere annually. That means that top layer ocean also does not absorb 50% of man's annual output or anything close to that. A much better numerical match is the 2% of man's total excess as I stated above. Another caveat is that the CO2 annual release doesn't mix worldwide in the atmosphere that quickly, but neither does the fossil CO2 in your scenario (it is also mostly NH). Briefly looking at Archer 2008, he and I agree when he states "Of the 9 Gton C/year carbon release from fossil fuels and deforestation from the year 2000 to 2006, 5 Gton C/year is taken up naturally, half by the ocean and half into the terrestrial biosphere (Canadell et al. 2007). One might conclude from these numbers that the uptake time for CO2 must be only a few years, but this would be a misconception. The rate of natural CO2 uptake in any given year is not determined by the CO2 emissions in that particular year, but rather by the excess of CO2 in the atmosphere that has accumulated over the past century. " Other than that, we aren't talking about the same processes since I am referring to the response of the top layer ocean with reasonable turnover to the deep ocean (I have explained on other threads why the deep ocean turnover is so high, it is the reason that the observed warming lags the theoretical warming). His paper discusses an active ocean and other active GHG production made active by AGW. My spreadsheet assumes (and matches the reality to the current day) that the system is passive.
  49. Eric@98 I do not think the conclusion in the third paragraph of your post is supportable. Just because the oceans do not rapidly take up half of the seasonal variation (which is mainly due to changes in the terrestrial biosphere) does not mean that the ocean is not absorbing half of anthropogenic emissions on an annual to decadal scale. The pre-industrial approximate equilibrium means that fluxes between the terrestrial biosphere and oceans must be in approximate balance (otherwise one or the other would be depleted). So it is very unlikely that the surface oceans were mopping up half of the excess forming the seasonal cycle, unless it were giving it back again in the oposite phase of the cycle. If you look at the annual ratio of the increase in atmospheric CO2 to anthropogenic emissions for that year, you will find it is very noisy and only averages out to about 45% over the course of a number of years. Weather noise is so great that you can't get a reasonable estimate of where the carbon goes on a year-to-year time-scale, without the use of physical models.
  50. Dikran, when you say "So it is very unlikely that the surface oceans were mopping up half of the excess forming the seasonal cycle, unless it were giving it back again in the oposite phase of the cycle." I assume you mean preindustrial? Then I am in violent agreement. Why would it be any different from today, except for the year over year increase from fossil fuels? The total fluxes are much larger than the net fluxes from seasonal vegetation (I routinely read 100 Pg of C). However, where I think we differ, is that there is no evidence that the oceans are mopping up any more than a very small portion (a few percent) of the seasonal excess. I noticed the weather noise in the papers and that does argue the opposite of my conclusion, that the top layer ocean is very actively sequestering and releasing CO2 essentially based on ENSO. The problem is that worldwide averages such as average SSTs are quite useless in this situation since the sequestration and release of CO2 from that top layer is very nonlinear. So like you say, we can't do it without a model and that model has to be girdded with some detail.

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