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CO2 is not the only greenhouse gas, and greenhouse effects are not the only CO2 problem

Filed under: — gavin @ 7 July 2008 - (Español)

The title here should strike a familiar theme for most readers. Climate forcings do not just include CO2 (other greenhouse gases, aerosols, land use, the sun, the orbit and volcanoes all contribute), and the impact of human emissions often has non-climatic effects on biology and ecosystems.

First up last week was a call from Michael Prather and colleagues that the production of a previously neglected greenhouse gas (NF3) was increasing and could become a significant radiative forcing. This paper was basically an update of calculations done for the IPCC combined with new information about the production of this non-Kyoto gas.

Most of the media stories that picked this up focused on the use of this gas in a particular manufacturing process – flat screen TVs. Thus the headlines almost all read something like “Flat-screen TVs cause global warming”! (see here, here, here etc.). Unfortunately, very few of the headline writers read the small print.

NF3 is indeed a more powerful greenhouse gas than CO2 (as are methane, CFCs and SF6 etc.), but because it is much less prevalent, the net radiative forcing (as with other Kyoto gases) is much smaller. Unfortunately, no-one has any measures of the concentration of NF3 in the atmosphere. This is likely to be increasing, since production has stepped up rapidly in recent years, but the amount of gas that escapes to the air is unknown. Manufacturers claim that it is only a very small percentage – but historically such claims have not always been very reliable. However, it is almost certain that NF3 has not caused a significant amount of global warming (yet).

The one issue that many stories did get wrong was in the comparison with coal. Prather’s paper compared the effect of the entire global production of NF3 being released into the atmosphere with the CO2 impact of one coal-fired power station. Since that is the maximum estimate of the current effect, and only matches a single power-station, the subtlety of the comparison got a little lost on the way to “Flat screen TVs ‘worse than coal’” story….

Needless to say, no-one should be throwing away their flat screen TVs because of this (it’s not in the use of the TV that causes a problem), but manufacturers will likely need to step up monitoring of NF3 leakage or switch to an alternative process which some have already done.

The second story getting some attention, is the ocean acidification issue. As we’ve discussed previously, the increased take up in the oceans of human-released CO2 is rapidly increasing the acidity (lowering the pH) of the oceans, making it more difficult for many carbonate-producing organisms to produce calcite or aragonite. These organisms include corals, coccolithophores, foraminfera, shell fish etc.

Both of these issues are relevant to the ongoing climate change discussion and it’s good to see the media picking up (albeit imperfectly) on these ancillary discussions. But as with the “North Pole” lightning rod discussed last week, there always needs to be a hook before something gets wide press (the ‘tyranny of the news peg’ as ably described by Andy Revkin). In the first case, there was a link to a popular consumer item and in the second, there has been a concerted effort to get the ocean acidification issue higher up the agenda.

The fact of the matter is that most of what goes on in the sciences is completely (and usually correctly) well below the radar of the public at large. But when there are discoveries and issues that do have public policy ramifications, getting the public to pay attention often requires finding just these kinds of resonances. Now if there was only a way to make sure the story underneath was accurate….

232 Responses to “CO2 is not the only greenhouse gas, and greenhouse effects are not the only CO2 problem”

  1. 51
    Figen Mekik says:

    John Lang: Trilobites and ammonites did not live at the same time, except during the Late Paleozoic when the trilobites were few and very much on the decline before their total extinction 245 milion years ago. Also trilobite carapaces aren’t necesssarily made of carbonate. Ammonites became dominant in Mesozoic oceans after the trilobite extinction.

  2. 52
    David B. Benson says:

    Chris (45) — Yes. Thank you for the correction and the amplification.

  3. 53
    Doug Bostrom says:

    #49 Aaron:

    You can save the RC folks some time by rephrasing your question as what you already believe. I’m hazarding a guess that your point is “Well, the earth has experienced periods of non-equilibrium in the past, so what’s wrong if it isn’t in equilibrium now?”

    Once you’ve done that, somebody can pipe up with the answer, probably to the effect that avoidably putting the system out of equilibrium in a way that will cause it to restabilize at a sub-optimal point is undesirable. I’m not I’m expert, but that’s probably the general gist of your “answer”.

  4. 54
    John Mashey says:

    A lot of the press reports on NF3 were confused, in the sense that they focussed mostly on flat panel displays, and thought the mention of plasma had something to do with plasma displays…

    Plasma etching is a step in semiconductor manufacturing, and is different from the “plasma” in plasma displays.

    NF3 is one of several choices used with CVD (Chemical Vapor Deposition) processes in general, i.e., in products that include:

    – microprocessors, DRAM, etc
    – flat-panel displays
    – photovoltaic solar cells

    To be clear, it’s one of the substances used in the manufacture of the products, it’s not *part* of the products (and better be long gone before the product ships), and actually, flat-panels may well be the lesser of uses.

    As to why it’s used (it’s only one alternative), see Gas World, which says:

    “NF3 is used as a chamber cleaning gas in the manufacture of semiconductors, flat panel displays and other electronic devices. When compared with competing products, NF3 offers customers significant reductions in emissions, throughput increases of up to 30%, longer chamber life and faster clean rates.

    Nitrogen trifluoride is also used in the plasma and thermal cleaning of CVD reactors, while it is used as a source of fluorine radicals for plasma etching of polysilicon, silicon nitride, tungsten silicide and tungsten for example.

    Although semiconductors remain the principal driver for electronic specialty gases, increased interest in photovoltaics is adding to the push.

    Electronic gases are needed in thin-film deposition, such as chemical vapour deposition (CVD) or physical vapour deposition (PVD), technologies used to make a semiconductor or a photovoltaic cell.

    The three major gases used in semiconductors, liquid crystal displays (LCDs) and photovoltaics are nitrogen trifluoride (NF3), silane (SiH4) and ammonia.

    Demand for electronic gases in the semiconductor and solar cell industries continues to outpace global GDP growth by more than two times. In traditional semiconductor segments such as microchips and flat panel displays, market researchers expect sales growth of around 8% per year between now and 2010 – and for the solar segment, the annual forecast lies at around 30%.

    Experts anticipate that from 2012, photovoltaic producers will spend more on gases than flat-screen manufacturers, and from 2017 they are even set to overtake the chip sector.

    Although only a handful of different gases are used in solar-cell manufacturing – in comparison with more than 20 for semiconductors – the volumes required are significantly greater.”

    SO, as usual, one must be careful with popular press. They whacked flat-screens, which are second to semiconductor chips, and will likely be third to PV cells.

    I haven’t seen the full Prather article, but:

    1) WE certainly do need to be measuring this.

    2)However, if there’s one place where chemicals are *very* carefully controlled, it’s a semiconductor fab, thank goodness. Equipment vendors (Applied Materials, etc) and fab operators certainly need to pay attention to keeping this under control or (maybe) finding alternatives, but it may be a potential problem reasonably kept under control. Again, fabs are at least used to working with witches’ brews of nasty chemicals.

  5. 55
    pat n says:

    Re #29

    What you said is probably true, but politics (and big money) does not explain why NWS
    deliberately kept climate change below the radar screen during the Clinton/Gore administration.

  6. 56
    Chuck Booth says:

    Re # 45 Chris
    “… this identical CO2-carbonic acid-bicarbonate-carbonate equilibrium maintains the homeostatic pH in our blood (pH 7.4)…a relic of our evolutionary deep oceanic past.”

    As you seem to be quite familiar with aqueous carbonate chemistry, I’m surprised you would end with a statement such as that. The CO2 buffering system in our blood doesn’t involve carbonate to any significant extent, as there is little carbonate at pH 7.4 (as you noted, the HCO3-/CO3= reaction has a pK around 10.3) . Second, the pH of 7.4 is maintained largely by amino acids, such as histidine (mostly in proteins and peptides), having a pK in that range; the pK for CO2/bicarbonate is a full pH unit lower (again, as you noted). Our blood chemistry is no doubt a carry over from our piscine ancestors, but most fish have a blood chemistry (i.e., concentrations of specific ions) very different from that of seawater. However, the CO2/bicarbonate buffer system is a fundamental property of aqueous systems, period – it is not restricted to seawater.

  7. 57
    Aaron says:

    On the subject of ocean acidification, how much CO2 gets dissolved in the oceans on a day to day basis? Also, the Henderson-Hasselbalch doesn’t really apply here because there are other organism that use CO2 for other physiological functions, namely photosynthesis. Even if it was, you would first need a rough estimate of the amount of base to CO2 as an acid to know the effect of the unused CO2. I’m also guessing that most of that base is in high concentrations in reefs and other places where life is most likely found. Since CO2 is just as likely to dissolve anywhere in the ocean, even a large amount of CO2 dissolved would have little impact since its concentration will be much diluted and many orders of magnitude smaller than the concentration of the base say in a crab’s shell or a coral reef. Diffusion is a powerful process.

  8. 58
    Aaron says:

    #53 Doug

    There are stable fluctuations from equilibrium and there are unstable ones. The question is whether or not the earth existed in a stable equilibrium before the industrial revolution. Also, how would one tell if an equilibrium is stable or not other than the usual stat mech definitions of compressibility and heat capacity? I know that there is an attractor the atmosphere, but can the atmosphere venture far from this point in phase space? If so, how far?

  9. 59
    Aaron says:

    #53 Doug

    The question does not have an answer as far as I know. I would not have asked it if I thought I had the answer. I know that some fluctuations in a grand canonical ensemble, like the earth, are stable, meaning that they will return back to the same equilibrium state after the fluctuation. That’s how one knows that as you increase the amount of energy you increase the temperature. It is a stability requirement of the ensemble. I just wanted to know if this picture is applicable to the earth system with a solar sunlight bath reservoir in equilibrium. Its really a statical thermodynamics question.

  10. 60
    Blair Dowden says:

    Re the response to #11: Gavin, I have been trying to get a better understanding of the lifetime of methane than the usually quoted ten years. But can you please explain your statement “For CH4, 12 years for the perturbative half-life (longer than the ~8 year residence time) is reasonable. How can half-life be longer than residence time?

    [Response: CH4 has what is called a feedback on it’s own lifetime. CH4 loss is controlled by the OH- concentration, but if you increase CH4, you use up OH-. The residence time is the total amount of CH4 divided by the loss rate (roughly 8 years), and if the loss rate was constant, then perturbations would decrease with an 8 year time-scale. But since the loss rate actually goes down if you increase CH4, that means that perturbations last a little longer than that (roughly 12 years). There’s more discussion (taken to extremes) in Schmidt and Shindell (2003). – gavin]

  11. 61
    Lowell says:

    The article says 4,000 tonnes of NF3 were produced last year and the CO2 equivalent of NF3 is 17,000 times that of CO2.

    While those numbers sound shocking, the CO2 equivalent of current NF3 production of 68 million tonnes should be compared to the CO2 production amounts of roughly 40 billion tonnes (ie, this is 1,000 times smaller than CO2 or a forcing of let’s say 0.0017 W/m2)

  12. 62
    Rod B says:

    Gavin, Chris C., thanks for the help.

  13. 63
    Thomas says:

    One of the comments claimed the warming effect of the NF3, was similar to that of a single coal plant. If I were to take that statement at face value then the impact of this chemical is pretty small, in fact probably very much less than any CO2 released by the production of the power used by those displays. If that is the case, then this chemical needs a small amount of monitoring just in case either its effect has been grossly underestimated, or its usage grows dramatically. It hardly seems like an issue of general concern.

  14. 64
    pft says:

    The atmosphere holds 760 gigatons of CO2. Man emits about 6 gigatons of CO2. The total emissions from all sources are about 200 gigatons (I have seen numbers as low as 150 gigatons so clearly the level of understanding of the carbon cycle is poor), and each year there is a net uptake of about 3 gigatons. So 98.5% (98%) of all CO2 emissions are absorbed into the various sinks. How exactly is mans CO2 emissions due to energy consumption contributing to the 3 gigaton uptake. Shouldn’t our share be 3% (or 4%) of this, or 0.09 (0.12) gigatons? And how does CO2 stay in the atmosphere for 100 years or more when 30% (20%) of CO2 in the air is removed from the air each year. Seems the half life would be 3-5 years?.

    Not saying man is not affecting things, and not saying CO2 is not responsible for part of the warming, or that there is not any warming. Deforestation, urban island effects, agricultural practices and other pollutants certainly must contribute to whatever changes man is responsible for, and natural variation in climate may be a factor. But I want to stay focused on man made CO2 from fossil fuels and why it takes the heat for global warming.

    [Response: Because it has increased ~100ppm (37%) over pre-industrial levels – all of which is due to human emissions. Your calculations are wrong because you are neglecting that the ocean/land sources are almost in balance with the sinks, but that the real sink out of the land/atmosphere/upper ocean system is the flux into the deep ocean, which is much slower. Think of it like a bath tub that has a tap turned on and a small drain and has reached a stable level. In the bath there is someone sloshing the water from one side to the other. Now you come along and pour in some buckets of extra water – the average level will rise depending on how quickly the small drain responds, but it is doesn’t depend on the sloshing at all. – gavin]

  15. 65
    Chris says:

    Re #56:

    Chuck: yes, you’re right that the bicarbonate – carbonate pKa is too high for this equilibrium to make a significant contribution to pH buffering in blood. It’s almost exclusively the carbonic acid-bicarbonate equilibrium that is involved. I used the entire equilbrium (carbonic acid-bicarbonate-carbonate) since, if there’s any hydrated CO2, the full equilbrium is represented, distributed amongst the various species according to the pH (it’s just that there is a minimal contribution from dissociation of bicarbonate to carbonate at blood pH).

    The carbonic acid – bicarbonate equilibrium is an important pH system in blood ‘though, and especially so since the blood is continually coping with changes in CO2 concentration. So just in the same way that outgassing of CO2 from oceans results in a rise in ocean pH, so the “outgassing” of CO2 from blood (through the lungs) “pulls” protons from the blood onto bicarbonate and raises the pH (and if the pH becomes too alkaline, bicarbonate is removed by the kidneys).

    Interestingly, whereas the reversible hydration of dissolved CO2:

    CO2(aq) + H2O == HCO3- + H+

    is quite a rapid reaction (half life around 5 seconds) so that CO2 equilibrates between the air and ocean surface according to the temperature and atmospheric CO2 concentration (and ocean surface dissolved CO2 concentration -equilibration of which with the deeper ocean layers is limited by the physical mixing of surface and deeper layers presumably), this reaction is catalysed in blood by carbonic anhydrase resident in our red blood cells, each enzyme molecule of which can bind and hydrate 1 million CO2 molecules to bicarbonate every second.

    The other buffering components of blood pH are proteins as you say (especially haemoglobin which binds protons), and also inorganic phosphate which has a pKa (6.8) closer to blood pH…

  16. 66
    Alan says:

    The Great Barrier Reef has proved to be an effective ‘hook’ here in Australia. A google news search gives you an idea. The turn-around in the average aussie’s attitude to climate change in the last couple of years has been nothing less than stunning, it and Iraq were the major factors in the recent election.

  17. 67
    Eric says:


    As a geneticist I thought I should comment on adaptation in general to give a picture of what effect “strong” (whatever means strong) acidification could have.

    Biological organisms have been shaped by their environment, are still shaped nowadays and will still be shaped tomorrow.
    They are, in parallel, shaped by “random drifting” based on their ability to acquire changes (mutate).

    So we have two forces that are specific for each organisms and even (but to a lesser extend) to each individual of a given species:

    1) Speed of genetic changes (intrinsic, species specific & in more moderate way individual specific)
    2) Speed on environmental changes (extrinsic, global, regional,…)

    if genetic changes match environmental changes -> good you survive & proliferate
    if genetic changes fit less well with environmental changes -> well you survive less and you know what ? it’s a competition ! so you should change yourself or the environment otherwise you’ll disappear.

    So it is true that species and some individuals in these species may have kept or re-acquire a greater resistance to acidification allowing them to cope better with acidification changes.
    It should also be noted however that there is even more species and individual that did NOT maintain such resistance or even became very sensitive to acidification. For example all these organisms that were spared from acidic environment for long (evolutionarily speaking) periods of time.

    To simplify, the more brutal the change (evolution scale remember) the more species and individuals will be eliminated (strong selection), the slower the change the more species and individual will be maintained (weak selection).

    I think corals (a lot of coral species but not all) are a good example of organisms that are sensitive to acidification. Many coral species may disappear, very few may survive and even expand reducing diversity until they drift to recreate a certain diversity.
    But the stronger the acidification, the smaller the number of species that can survive and the smaller their possibilities to evolve (strong constraints limits possibilities).

    Hope I haven’t been too much off-topic…

  18. 68

    Aaron writes:

    From an expert’s point of view, was the earth in a thermal equilibrium with the incident flux of sunlight before the industrial revolution?

    Yes, and on short time scales, it is now. If it weren’t, Earth would heat up or cool down, as required, until balance is restored.

    We’re a bit out of balance now, and staying that way, because the amount of greenhouse gases in our atmosphere is steadily increasing. But to a first approximation you can model the Earth’s atmosphere very closely by assuming radiative equilibrium at top-of-atmosphere.

  19. 69
    Willem Vanden Broek says:

    Somewhat off topic, but speaking of other greenhouse gasses, in this case ozone, Alastair Lewis was interviewed on the very pro-environmental National Public Radio show Living On Earth (see ) broadcast this weekend. It was very upbeat on global cooling from tropical ozone depletion due to bromine and iodine, probably from sea spray. The following exchange was particularly interesting to me:

    ELLERMAN: So I guess this is really gonna change our perspective on climate models and change the climate models?

    LEWIS: Well it certainly shows that we need to keep an open mind, that actually there are some things out there in remote places that are pretty important, that we actually haven’t discovered or accounted for yet, that it’s not a completely done deal in terms of the chemistry of the atmosphere, that there are still some discoveries to come. Understanding how the climate works is still subject to big uncertainties so there are big processes that perhaps we haven’t discovered, or processes that we don’t understand accurately and we need to go to these places to really try

    [Response: What you see is a journalist asking a seemingly important question and the scientist trying to get back to what they know about. There is no ‘global cooling’ from halogens above the ocean, since there is no reason to expect them to be changing. What this does is affect the background state for ozone in chemistry-climate models in some regions, which is likelyl to have little or no effect on changes in ozone due to increased emissions of precursors. It’s obviously better to get all these details in, but the whether this is ‘really gonna to change our perspective on climate models’ – the answer is no. – gavin]

  20. 70
    Paul says:

    O.K. I’m going to ask low-level question of the day.

    T. Boone Pickens this week announced plans to set up (on private property, minimal governmental approval needed) a network of windmills to generate power. The radio show I was listening to this morning, Brad & Britt on WZTK in Greensboro (not a national show, and usually rather balanced. One of them is conservative and one is liberal, both have shown a lot of leaning towards environmental conservatism), they said the plan was to try to string enough power generation together to power 50 million households.

    Will that amount of power generation reduce the production need enough for some of the other non-environmentally friendly power plants to stop producing so much polution? With the Majove desert solar projects, the current Hydro-electric and nuclear plants online and now the wind project, would that be enough to pull coal out of the equation? Or somewhat close?

    (As was proven on another thread, I’m somewhat new to the game, so asking those who know to see if there might be some hope…)


  21. 71
    Chris says:

    #57 Aaron

    Yes the Henderson Hasselbalch equation applies here. The H-H equation effectively defines the equilibrium distribution of the basic (proton acceptor) and acidic (proton donor) components (conjugate pair) of a titratable group (a buffer). So it can be used to calculate the ratio of carbonate/bicarbonate (or the absolute concentrations of these if the total buffer concentration is known, which I’m sure it is in the oceans – it’s around 27 mM in blood, of which nearly 26 mM is bicarbonate) in the oceans, in blood or in a bucket.

    It doesn’t really depend on other organisms [if a photosynthetic algae uses a bit of dissolved CO2 this will have a tiny effect on the CO2-carbonic acid-bicarbonate-equilibrium, but this will just “readjust” (Le Chatalier’s principle) and (assuming the local sea pH doesn’t change), the equilibrium ratios of conjugate acids and bases (e.g. carbonic acid/bicarbonate) won’t change].

    I’m not sure what you mean with:

    [“Even if it was, you would first need a rough estimate of the amount of base to CO2 as an acid to know the effect of the unused CO2. I’m also guessing that most of that base is in high concentrations in reefs and other places where life is most likely found.”]

    Notice that in the Henderson-Hasselbalch equation “base” means “basic component of the buffer”.

    So in the equilibrium:

    H2CO3 === HCO3- + H+ === CO3- – + H+

    Bicarbonate is the “base” when considering the carbonic acid – bicarbonate equilibrium and is the “acid” when considering the bicarbonate – carbonate equilibrium. So I wonder if you are using the term “base” in the same manner that I, and Mssrs Henderson and Hasselbalch, are! Obviously carbonate is the most basic component of the buffer. So if that’s what you are referring to, I see sort of what you are saying with respect to the reefs/coral etc. However this carbonate is essentially “fixed” (as aragonite or calcite)..the carbonate in equilibrium with bicarbonate in sea water is dissolved carbonate. That’s not to say that the “fixed” carbonate (in shells and skeletons of sea creatures) isn’t also in “equilibrium” with the dissolved carbonate, and of course one of the problems of ocean acidification is that the shift in the carbonate/bicarbonate equilibrium even further towards bicarbonate enhances the leaching of “fixed” carbonate back into solution…..

    …i.e. the shells of the poor sea creatures start to dissolve…

  22. 72
    Ray Ladbury says:

    When we speak of nonequilibrium thermodynamics, we are really talking about near-equilibrium thermodynamics. There really aren’t great methods for treating systems that are far from equilibrium. However, most systems do not spend a significant proportion of time far from equilibrium, and this includes Earth. The concept of local thermodynamic equilibrium applies except right at the top of the atmosphere. The boundary condition is tricky, but can be handled.

  23. 73
    Pete Best says:

    Re #72, apart from Life itself perhaps which is far from equilibrium.

  24. 74
    Alastair Brand says:

    Am I missing something here? At home, I have copies of publications going back to the early 1980’s, which refer to the problem of increased oceanic acidification due to enhanced levels of atmospheric CO2. So why are certain sectors of the media only beginning to take notice of a “new” issue now?

    This ought to be given more prominence; one of the main contentions in “The Great Global Warming Swindle.” last year, claimed that the oceans could be a net exporter of CO2 to the atmosphere, resulting from increased temperatures (entirely natural, of course) But if oceans are acidifying as a result of increased CO2 uptake, they logically cannot be a net exporter of CO2 back to the atmosphere.

    Yet most people I have spoken to, on both sides of the divide, appear not to have even heard of the issue of acidification.

  25. 75
    Ron R. says:

    As for other factors contributing to AGW, let’s not forget all that carbon released by all the fires (800 currently in California alone) caused by the extra heat and drought caused by AGW. A vicious cycle that will probably snowball. And drought will unfortunately probably mean less regrowth of carbon-eating trees and more initially of dryland chaparral communities and giving way finally to desert conditions.

  26. 76
    Aaron says:

    #71 Chris

    But if the Henderson-Hasselbalch equation is applicable after accounting for the amount CO2 has been used to photosynthesize sugars, and concentration of base, from the definition in the equation (either single or bicarbonate), is much, much higher than the trace amount of CO2 that are dispersed throughout the ocean, based on an analysis that would like the Langmuir adsorption isotherm, how can these traces amounts of the acid (CO2) contribute enough to dissolve crabs’ shells which have a much higher concentration of the base? We are taking a small number and dividing it by a bigger number and then taking a log. That sounds like a very small number to me. Also, if there is more CO2 for more algae to make more sugar and then more algae, that puts more carbon to turn into carbonate by crabs and the like. So carbonate may not be truly fixed, but there are definitely competing processes. The question is, once these other factors are accounted for, production of new carbonate from more microorganisms and consumption of CO2 by said microorganisms, what does this do to the relative concentrations of both bases and CO2 at the point of activity?

    #72 Ray

    If the common practice is to treat the earth as a thermal system in equilibrium with a sunlight bath, what is a rough estimate for the absolute magnitude for the largest stable fluctuation in the internal energy of the earth? I would guess that this might be related to the square root of number of particles in the atmosphere as would be the case for a grand canonical ensemble, but I don’t if that is allowable with the different physical phases found in the atmosphere (i.e. gas, clouds and crystals).

  27. 77
    Joseph says:

    We’re a bit out of balance now, and staying that way, because the amount of greenhouse gases in our atmosphere is steadily increasing.

    Out of curiosity, how do we know that we’re not completely out of balance right now? In other words, what if temperature is rapidly increasing primarily because we’re not in equilibrium, regardless of whether green house gases continue to accumulate in the atmosphere? Can this scenario be discounted? If not, is there a reliable way to know when equilibrium should be expected to be reached?

  28. 78

    I thought this was interesting new analysis on methane in the ocean

    It came out on July 4th, seems to be in the positive feedback progression.

    From Article:

    Although the implications for global climate change are still being studied, the warming and further stratification of the ocean seem likely to affect marine methane production. “This is a newly recognized pathway of methane formation that needs to be incorporated into our thinking of global climate,”

  29. 79
    Aaron says:

    #77 Joseph

    Using Kirchoff’s Law one can tell whether or not a graybody like the earth is near or far from equilibrium. This is done by related the amount of incident radiation from the sun is absorbed and how much the earth thereafter emits. If the ratio of these two factors stays relatively constant, which it has for the earth, then one can assume that the earth is pretty close to equilibrium. This is how greenhouse gases play a role in this drama. More CO2, CH4, H2O and other gases there are, the bigger the absorption and an increase in T. But so far, this has been a hard thing to measure so I would say that it is up in the air at best.

    Also, it is very hard to push a system as big as the atmosphere far away from equilibrium. I would even say that the amount of CO2 we put into the atmosphere would not even make the internal energy of the atmosphere fluctuate enough to not have it come back to equilibrium some other way, but this is just a hunch. I mean , if we pushed the atmosphere so far from equilibrium, how have the last three very large volcanic events have not done the same in the other direction?

    [Response: This is extremely confused. Kirchoff’s law says no such thing, the greenhouse effect is not a hard thing to measure and is not ‘up in the air’ in any sense except literally. Volcanoes do have large negative impacts on the TOA radiative balance but they don’t occur frequently enough to have cancelled out the increasing effect of GHGs (see here). – gavin]

  30. 80
    Jim Eager says:

    Re pft @ 64: “The atmosphere holds 760 gigatons of CO2. Man emits about 6 gigatons of CO2.”

    Out of date figures, human emissions are currently over 8Gt per year.

    “The total emissions from all sources are about 200 gigatons…and each year there is a net uptake of about 3 gigatons”

    That’s 3Gt of human generated CO2 (measuring just the C, again should be ~4Gt currently). As Gavin pointed out in his response, total natural emissions and uptakes by natural carbon sinks are roughly in balance, plus the sinks are also taking up roughly half of human emissions. Hence the rest of human emissions, ~4Gt, account for all of the annual increase of 2+ppm/yr.

  31. 81
    Chuck Booth says:

    # 76 Aaron

    Chris was correct about the H-H equation – in its standard form, it relates pH, dissolved CO2 gas concentration, and bicarbonate concentration. If one of those values changes (e.g, bicarbonate is taken up by photosynthetic algae, or excreted by the kidney), the other two will change in a predictable way (once equilibrium is re-established, and assuming there is no change in temperature or salt content, which could alter the pK a bit).

    Chris: The point I was actually trying to make (# 56), but didn’t make very well, was that the CO2-bicarbonate buffering system is an unavoidable consequence of life based on an aqueous environment in the cells and other body fluid compartments. The homeostatic mechanisms that keep our blood pH at 7.4 (and keep fish blood pH at 7.7-8.0, depending on the temperature) are, in large part, those that evolved to regulate the components of that buffer system, i.e., elimination of CO2 by ventilation of gills and/or lungs) and uptake or excretion of bicarbonate and H+ via ion transporters in gills and/or kidneys. Your statement seemed to suggest that it was the chemical buffering system that maintained homeostasis, whereas I would argue that the buffer system merely responds to changes resulting from physiological processes subject to feedback control; homeostasis is (usually) the result. In short, I was merely nitpicking a bit for the sake of clarity and accuracy. You obviously understand the physiology quite well.

  32. 82
    Ray Ladbury says:

    Joseph, I’m not sure what you are asking? The climate is not behaving like a system far from equilibrium, but rather like an equilibrium system perturbed from that equilibrium by a forcing.

    Aaron, I’m not sure that your question is a reasonable way to look at a dynamical system with components that interact on very different timescales. That’s sort of the problem Schwartz had with his overly simplified depiction of climate. But basically, the answer to your questions is that different scales of fluctuations will happen with different probability distributions on different timescales. That’s the noise. The thing is that none of the noise has a monotonically increasing character, so the longer the timescale, the more–on average–we expect to see trends due to CO2.

  33. 83
    Tom Dayton says:

    Re #69, the NPR interview of Lewis:

    When I heard the interviewer ask that loaded question during the broadcast, I started yelling warnings at Lewis as I yell at characters in bad horror movies who are about to open the closet from which blood is dripping.

    Lewis’s response was perfectly adequate for a listener who knows what Lewis knows. Unfortunately, he didn’t preface his response with a sufficiently simple and strong answer for listeners who are less in the know, or listeners who know incorrect things.

    I certainly don’t blame Lewis. He was thinking on his feet, his answer was excellent for some audience members, and he seemed to be giving the interviewer the benefit of the doubt. Unfortunately, nowadays I think all interviewees on any topic that might remotely have a connection to climate change should prepare for interviews by preparing one short, strong, unequivocal, clear sentence about the relation of their topic to climate change. They should write that sentence on a note card that they keep in front of them during the entire interview, so they can read that sentence on a moment’s notice.

  34. 84
    Mike says:

    I apologise in advance for what I know is a bit off topic – even though it is very much connected with AGW. I am sitting here on an English summer day suffering the dismal drizzle dripping form a grey gloomy sky all brought on by a deep and slow moving mid-latitude cyclone (depression)that has hovered over Britain for near 48 hours. A seemingly endless succession of such depressions have sluiced their way across NW Europe this year – and indeed even the western Mediterranean has not been unassailed by damp and dripping depressions. I am recently back from Tuscany and Rome in not so Sunny Italy where one period the deluge was continuous in a Scottish Highlands sort of way for 36 hours. The dreary summers afflicting Ireland, Britain, France, Scandinavia and Benelux as well as Spain, Portugal and Italy are causing increased scepticism about the reality of global warming.

    There is I believe, research that suggests that the higher temperatures associated with increased levels of greenhouse gases may be reflected in an increase in the intensity (though not the frequency) of tropical cyclones – hurricanes and typhoons etc. Presumably, deeper cyclones with higher winds and heavier rain would ultimately result from the warmer air of the present having a higher maximum possible absolute humidity than the cooler air of before AGW i.e. the warm air has a higher “capacity” for water vapour, than does cool air. When warm air rises and cools adiabatically, the water vapour condenses our, releasing latent heat, encouraging continued rising, cooling, and condensation under conditions of instability when adiabatic lapse rates are higher than the environmental lapse rate. In short, warmer air may provide more energy to the cyclone to result in higher windspeeds, lower barometric readings at the centre of the cyclones, and heavier precipitation.

    Could such processes also be operating in mid-latitude depressions that develope over the west Atlantic and move north west to Europe? Is there any evidence that mid-latitude depressions/cyclones are more intense (and perhaps more frequent) than say 50 or 100 years ago? Does anybody know of any research that has looked into
    1. Possible increases in pressure gradients within depressions
    2. Increased mean windspeeds.
    3. Increased intensity of precipitation.
    4. Increased frequency of depressions.
    5 Increased complexity of frontal systems and occlusions.

    My thought is that global warming may actually increase uptake of water vapour from the oceans and in certain geographical areas – West Europe for example – result in increased cloud and storm, and possibly localised cooling relative to the rest of the globe.

  35. 85
    llewelly says:

    Joeseph, #77:

    Out of curiosity, how do we know that we’re not completely out of balance right now? In other words, what if temperature is rapidly increasing primarily because we’re not in equilibrium, regardless of whether green house gases continue to accumulate in the atmosphere? Can this scenario be discounted? If not, is there a reliable way to know when equilibrium should be expected to be reached?

    As this RC article explains, our planet is indeed out of radiative balance, and the temperature increase is due to not being in equilibrium. This is primary evidence for global warming – and this imbalance is entirely due to human-emitted greenhouse gasses. And indeed, substantial warming remains ‘in the pipeline’, and if GHG levels froze right now, we would still experience about 0.6 C further warming.

  36. 86
    Aaron says:

    Gavin, you’re right. The ratio is described does not have to equal a constant for there to be thermal equilibrium, it has to equal one. In the IR region, this is the case. Now for Kirchoff’s law to really make sense this has to hold true for all the parts of the em spectrum and I don’t know if this has been tested. If you know of data on the absorption and emission of radiation by the earth in regions like x-ray and gamma, please let me know. I would like to look at them. If you would like more information on Kirchoff’s law please see

    As for volcanoes, I was not suggesting that they could somehow offset the contributions of greenhouse gases by people. I was claiming that these large scale volcanic effects provide very large fluctuations to the internal energy of the atmosphere, modeled as a grand canonical ensemble. Despite these fluctuations the atmosphere is able to bounce back and return to the basically the same equilibrium position in a rather short period of time, much less than geological time. It would be interesting to see what the maximum absolute fluctuations in the internal energy would still allow the atmosphere to return to the same equilibrium state with the incident radiation from the sun and whether or not adding so much CO2 or other gas would provide this much of a fluctuation on what type of a time scale.

  37. 87
    Mark says:


    Leaf dies and rots. CO2 released.

    Leaf grows. CO2 sequestered.

    Unless we have fewer plants year on year (by, say, cutting them down…) this is a balance. That there are a quadrillion tons of leaves means nothing. They all grow back.


    We extract the oil and burn it. CO2 released.

    We ????

    Ah. We don’t have a natural sink for this.

    So even 1 ton of CO2 burned needs to be taken up by something else. And you need to PROVE this single ton is taken up because the default is “nothing”. you must prove your assertion to a skeptical crowd.

    When we note that it is trillions of tons of oil, we have problems.

  38. 88
    Joseph says:

    Volcanoes do have large negative impacts on the TOA radiative balance but they don’t occur frequently enough to have cancelled out the increasing effect of GHGs (see here)

    If I understand that graph correctly, there’s a clear trend in net forcing, which means we’re not in equilibrium, and getting further away from equilibrium.

    How do we know that, even if GHGs stay at current levels indefinitely, equilibrium will be reached, say, at a 2 or 3 degree anomaly vs. an 8 degree anomaly? In other words, can an assurance be offered that the current level of disequilibrium is not much more catastrophic than normally thought?

    Historically, it seems that an increase of 100 ppmv CO2 has quite a major impact on temperature (although I’m not sure to what extent that’s due to feedbacks).

  39. 89
    Jimbo says:

    Regarding the CO2 absorption or release question (posts 16, 39, 45, 46): the oceans absorb CO2 (check the NOAA numbers). Increasing atmospheric CO2 concentrations increase the air-sea flux, which has its most significant impact on the shallow surface waters. This causes increasing acidification in these waters due to the slow rate of deepwater formation, which would transfer the water with increased surface CO2 to the deep abyssal waters. Plus, the major impact is in the Pacific where carbonate saturation depths are shallow, but the significant transfer of water with increased TCO2 (and the associated carbonate system changes) is going to occur in the North Atlantic and the Southern Ocean.

    Slowing down the rate of atmospheric CO2 increase would thus slow down the rate of the increase of the air-sea CO2 flux. Reversing the increasing atmospheric CO2 trend (we can dream) would also reduce the air-sea CO2 flux, but I’m qualitatively sure that even if it goes down to pre-industrial levels, the air-sea flux of CO2 would still be into the oceans. But it would be closer to balance with deepwater formation rates, so there would much less acidification of surface waters.

  40. 90
    Chris says:

    #76 Aaron

    That’s very confused – you’re mixing up all sorts of unrelated concepts.

    The Henderson-Hasselbalch equation simply defines the ratio of the acidic and basic components of a buffer according to the pH and pKa. Nothing more, nothing less. It defines the position of a physical equilibrium. It’s got nothing to do with what animals do with CO2, sugars and so on. We’re talking about how dissolved CO2 in the ocean that is hydrated to carbonic acid further partitions between its monobasic (bicarbonate) and dibasic (carbonate) forms, and how this affects the ocean acidity.

    Carbonate-fixing animals in the sea fix various forms of carbonate (CO3- -) usually as CaCO3 (calcium carbonate, which in various forms like calcite and aragonite is the dominant component of shells/coral). The concentration of carbonate in sea water is small (around 230 umol kg-1 or 230 micromoles per kilogram of sea water), because the dissociation of bicarbonate to carbonate is not favoured in sea water (the equilibrium at the pH of sea water is almost 1000-fold in the direction of bicarbonate; see my post #45). As the pH drops further, due to increasing atmospheric CO2 concentrations, the equilbrium shifts even further away from carbonate towards bicarbonate. During the last 420,000 years through several glacial/interglacial cycles, it’s unlikely that the carbonate concentration dropped below 250 umol kg-1, so already the acidification of sea water resulting from our massive CO2 emissions has resulted in a very significant drop in the sea water carbonate concentration.

    This follows directly from the straightforward physical equilibrium described in my posts #45 and #71. As CO2 dissolves and is hydrated in sea water, the carbonic acid releases protons acidifying the water and shifting the bicarbonate – carbonate equilibrium further in the direction of bicarbonate. The carbonate concentration drops.

    It’s really as simple as that.

    How problematic is this phenomenon? Potentially very problematic. The sea water carbonate concentration that was in the range around 310-250 umol kg-1 during the last 420,000 years (calculated from CO2 concentrations from the Vostock ice core), has been reduced to 230 umol kg-1. Experimental studies have shown that carbonate accretion (“fixing”) on coral reefs drops to zero or becomes negative (aragonite leaching back into the water as dissolved carbonate) when the carbonate concentration drops to around 200 umol kg-1. That’s expected to occur at an atmospheric CO2 concentration of 480 ppm.

    These things can be calculated since they are simple physical equilibria. The effects on coral reef growth can be directly observed in field studies and experiments.

    A useful acount of the effects of atmospheric CO2 emissions on ocean pH and coral reefs was published recently:

    O. Hoegh-Guldberg et al (2007) “Coral reefs under rapid climate change and ocean acidification” Science 318, 1737-1742

  41. 91
    Rod B says:

    re Paul (70), actually Pickens’ North Texas 200,000 acre wind power project will (hopefully) by 2014 generate 4000MWatts, which is estimated to handle 1,300,000 average homes — about the same as two large nuclear power plants. … at a cost of about $12B (which also includes some transmission lines and a separate water delivery pipeline). This is a bit bigger than the 2700MW wind farm in West Texas and way larger than the 300MW the State is planning for the Gulf of Mexico, but is said to be the largest (planned) in the world to date.

    It’s curiously interesting since, as you probably know, T. Boone made his $billions over the last 50 years from oil and natural gas. It will be interesting to see if 1) he can pull it off (2 installed every 3 days over six years+ for the turbines alone in an area with virtually no infrastructure), and then 2) make any money off it (requires the continuing federal operating (tax) subsidy, e.g.)

  42. 92
    Guenter Hess says:

    @Thermodynamic equilibrium and earth

    Maybe somebody can enlighten me,
    I learned that for a macroscopic body in thermodynamic equilibrium all extensive parameters like pressure, volume, temperature, composition and number of molecules are independent of time.
    I learned also that thermodynamic equilibrium requires detailed balance on a microscopic scale. This means per example for two black bodies in thermodynamic equilibrium that the incoming intensity is balanced with the outgoing intensity in every wavelength interval across the spectrum.
    I also learned that the earth is an open system far away from thermodynamic equilibrium, but of course in a stationary state or close to it with radiative balance.

  43. 93

    #77 Joseph

    Slightly out of balance is subjective and relative.

    Maybe the best way to say it is to generalize. We were fairly in balance prior to the industrial revolution. The climate forcing was following the natural cycle and in a slight cooling trend.

    Then we added industrial based GHG’s which added forcing to the system. Now the ocean has to absorb the extra forcing to get a new warmer equilibrium. So getting back into equilibrium is not as favorable as it may sound.

    I’d rather attain equilibrium at a lower lever than where this is headed. But as Steven Colbert from the Colbert report has mentioned in response to Michael Griffins (NASA Director) statement about “who is to say the climate we have is the ideal climate…”, Colbert responding, “who are we to say that pacific islanders prefer their islands above water”

    We really don’t have a handle on the compounding of positive feedbacks, but there is some paleo precedence for an anomaly in the direction of 8 degrees. There is reason to lean toward the upward scenario, in my opinion, given variables, given BAU, given, what we know, et cetera, et cetera…

    Yes we are pushing further away from equilibrium at this point.

  44. 94
    Jim Eager says:

    Re Aaron @86: “Despite these fluctuations the atmosphere is able to bounce back and return to the basically the same equilibrium position in a rather short period of time”

    That’s because both volcanic ash and sulfuric acid aerosols don’t stay in the atmosphere very long, hence the forcing does not last very long.

  45. 95
    David B. Benson says:

    Paul (70) — Your question probably more properly ought to be asked on

    which is run by energy expert Joe Romm.

  46. 96
    Chris says:

    re #81 Chuck,

    Your nits are well picked….! In my understanding the carbonic acid-bicarbonate equilibrium does contribute to the maintenance of blood pH (as a very weak buffer 1 pH unit away from its pKa – it buffers somewhat against acidification which takes the pH back towards the pKa). However your depiction of a more “passive” role for the carbonic acid-bicarbonate equilibrium around which the physiology of pH homeostasis and O2 uptake/CO2 excretion evolved, is a beter way of considering the broader picture.

  47. 97
    Aaron says:

    #94 Jim

    The point I was trying to make with volcanoes, especially the big ones, is that when they erupt, they provide a very large, short impulse fluctuation to the earth’s atmosphere. Despite these very large fluctuations (Tambora created temperature differences of up to 20 degrees at some latitudes and even caused famine all the way across the world!) the atmosphere was still able to find an equilibrium that looked similar to that of before the eruption not long there after. I’m really just asking if there is some kind of estimate for how much the earth’s atmosphere can take it terms of a fluctuation. I know it can take large volcanic eruptions. If you integrate over enough time, does CO2 input from people push the atmosphere passed this fluctuation limit? I don’t know, but it seems like a pretty straight forward question from a pure physics standpoint. As far as I know, there is no reason to believe that this is an overly simplified point of view.

    #82 Ray

    Can you please give me some more information on Schwarz? I would be interested into seeing more of this person’s work.

  48. 98
    Steve Bloom says:

    Re #84: Mike, you make this statement —

    “The dreary summers afflicting Ireland, Britain, France, Scandinavia and Benelux as well as Spain, Portugal and Italy are causing increased scepticism about the reality of global warming.”

    — and then ask if anyone has any statistics about these “dreary summers”? A climate shift along the lines of what you describe would be rather big news, I think. You can use the internet to look at the numbers and see if there’s anything to this. It shouldn’t take you long.

    Also, increased scepticism on whose part? Do you have some sort of survey data to back up this claim?

    Weather/climate and public opinion are two areas where sceptcism should first be applied to seat-of-the-pants personal assessments. Try that, please.

  49. 99
    Ray Ladbury says:

    Aaron, you can read about Schwartz here:

    Schwartz is not a bad scientist, but this shows what can happen when somebody with an incomplete understanding of the science wades too deep.

    I am curious about your contention that you are weighing “both sides” of the argument. Where are you getting the denialist side–because it sure ain’t in the peer-reviewed literature. The profession of publishing significant insights into climate while denying that humans are playing a significant role is absolutely moribund. So where is this “other side” you keep talking about.

  50. 100
    Tom Dayton says:

    Re #97, Aaron asked whether there is “some kind of estimate for how much the earth’s atmosphere can take in terms of a fluctuation.”

    Aaron, I infer you think the atmosphere has some sort of general-purpose equilibrator. It does not have mechanisms that per se strive for equilibrium of all the Earth’s characteristics. (The Gaia metaphor must not be taken too literally.)

    It does have some specific mechanisms that counteract some specific changes. But those mechanisms do not pay attention to whether they are exacerbating other changes.

    Jim’s example (#94) was that volcanic ash and sulfuric acid aerosols cool the Earth by reflecting incoming solar radiation. Those substances quickly precipitate out, thereby counteracting the specific effect of cooling from those specific substances.

    But suppose the Earth was already cooling, and so much so that it was heading into an ice age. The precipitation of the volcanic sputum then would exacerbate the global, net cooling trend from all influences.

    So that precipitation is not inherently a global equilibrator. It just does its own thing, sometimes with the global effect of counteracting net global trends (equilibrating), and sometimes amplifying those trends (disequilibrating).

    So the answer to your question of whether there is “some kind of estimate for how much the earth’s atmosphere can take in terms of a fluctuation” [my emphasis on “a”], is that there is no single answer, because the answer differs depending on the specific causes, directions, and sizes of the fluctuations.

    Back on point of Jim’s reply: Fluctuations due to volcanic eruptions peter out quicker than fluctuations due to, say, chronically increasing CO2 levels in the atmosphere.