Airborne Fraction

Dave Andrews wonders:


For all your pretty graphs aren’t you missing something here?

The Mauna Loa, et al, figures show a roughly steady increase in atmospheric CO2 but there has been a massive increase in the burning of fossil fuels since 1990, especially, but not restricted to, India and China.

This huge increase is not being reflected by the Mauna Loa figures.

Each year we emit lots of CO2 into the atmosphere, but not all of it remains there. A substantial amount (about 45% net) is absorbed by the oceans, biosphere, and other sinks that a real expert could elaborate. But if emissions have grown as rapidly as Dave Andrews implies, why hasn’t the growth rate of CO2 grown in step?

The answer is, it has.

I found emissions data from the Energy Information Agency. Figures are given in Mt CO2 (million tonnes CO2) but we can convert that to “ppmv” (parts per million by volume in the atmosphere) by noting that 7800 Mt CO2 (7.8 Gt CO2) is about 1 ppmv. Of course we can get CO2 concentration from Mauna Loa. Then we can compute, for each year, the annual change in CO2 (which I estimated as the difference between the annual average and the previous year’s annual average). Then we can compare CO2 growth to emissions directly.

Since only about 55% of emissions remain airborne, I actually compared CO2 annual change to 55% of emissions:

Emissions have indeed grown, and if you want to call the growth “massive” that’s OK with me. But if you do, you also have to refer to the increase in annual CO2 growth rate as “massive.” They certainly are comparable.

We can also, for each year, compute the fraction of emissions which equals the annual increment, i.e., the “airborne fraction” for emissions that year. And here it is:

Linear regression fails to detect any significant trend; it’s obvious that the airborne fraction fluctuates a lot from year to year, but there doesn’t seem to be any trend.

So no, it’s not true that the “increase is not being reflected by the Mauna Loa figures.”

55 responses to “Airborne Fraction

  1. Before you get the “Mauna Loa is near a volcano” argument, is it worth also plotting, say, Cape Grim, Tasmania along side it?

  2. Tamino

    Usually I have to run to try and catch up with your analysis. For the first time in 5 years, I have already done similar work that Dave Andrews may want to look at.

    Here is thelink to my CO2 emission – air borne fraction analysis along with links to my R Script and CSV files so that Dave can check the CO2 data for himself.

  3. I have already done similar work that Dave Andrews may want to look at.

    He won’t. Stuff like this is good for lurkers and others, but not true believers in climate science fraud like Dave Andrews.

    I mean … just google the guy … he’s been around the block a few times.

  4. One interesting point is the, as yet, lack of significant trend in the airborne fraction. One might expect that the oceans and terrestrial biosphere would begin to lose their capacity to absorb the anthropogenic CO2 emissions with time, so that the fraction of CO2 emissions remaining in the atmosphere would begin to increase above 0.55. There does not appear to be evidence of that occurring.
    That seems to be a crumb of comfort, since otherwise atmospheric CO2 would be increasing even more rapidly, but I guess one’s judgement on such matters may be influenced by whether one is a human being or a marine organism whose CaCO3 shell is in danger of dissolving in an increasingly acidic ocean.

  5. You expect Dave to check the CO2 data for himself.

    Good one, Kelly.

  6. I wonder what Dave Andrews was getting at though: that the Mauna Loa, etc., data are not to be trusted because he thought (wrongly, as Tamino has shown) that it didn’t reflect the increase in actual emissions? If not that, then what?

  7. Emissions by deforestation were 15-25% of annual CO2 emissions in these years, with high interannual variability. Maybe it explaines the variability here.

  8. TrueSceptic: yes, I think the point was supposed to be that the emissions didn’t match the atmospheric concentration increase.

    I’d guess that comes from plotting them on graphs with different units, different scales, and different basepoints, where the emissions graph might show a huge jump, but the CO2 graph barely a blip. Tamino’s first graph above is the obvious rebuttal to that, but putting two curves on the same graph with the same units & baseline to allow a true comparison seems to be beyond many of the ‘sceptics’ out there.

  9. Damien: “is it worth also plotting, say, Cape Grim, Tasmania along side it?”

    ‘MLO is a volcano’ is a dead stick of an argument. As long as you keep withing a band of latitudes, monthly CO2 curves are very similar around the world. There is, of course, very noticeable variation from south to north.

    Here’s a good library, in a handy map-based search, of the full range of greenhouse gases from around the world.

  10. Heigh-ho. Another day, another denialist own goal.

    Bound to happen, especially to those whose entire analytic repertoire is Eyeball Mark 1.

  11. The issue of sink saturation is tremendously interesting. I suggest two papers. One by Canadell and colleagues from PNAS in 2007:

    The second by Le Quéré and colleagues in Global Biogeochemical Cycles from 2010:

    I’d love to hear about other good lit on the subject.

  12. Daniel J. Andrews

    He won’t. Stuff like this is good for lurkers and others, but not true believers in climate science fraud like Dave Andrews.

    I mean … just google the guy … he’s been around the block a few times.

    He’s been around long enough and often enough that on occasion my moniker has been mistaken for his and I receive a blast from some frustrated science fellow in response to an antiscience idiocy he’s posted earlier on some climate blog.

  13. Dave Andrews

    That data you link from the EIA only relates to 2005-2009. It doesn’t go back to pre 198o as you show on your graph.

    You should look at the massive growth in fossil fuel consumption since the late 1980s and ask why it is not showing up in the Mauna Loa figures.

    [Response: Gee, sorry I didn’t include the link to all the data. I leave it as an exercise for you to locate the rest of it. They are still estimates from EIA of total emissions. Will it be the very first time you’ve ever bothered to get actual data before making false claims?

    I guess you’re really hurt by the fact that it was so easy to show your claim is false. Your lame attempt to insist on the phrase “fossil fuel consumption” is nothing but an attempt to cloud the issue — CO2 growth is a direct result of emissions.

    You refuse to believe the truth even when it’s shown to you in simple terms. Some might consider it unkind of me not to delete this comment, in order to save you the embarrassment.]

  14. Dave Andrews, I think Tamino is having a little fun at your expense. I can’t blame him.

    Follow the link to the data. Look for a drop-down menu labeled “Start Year”. Change it from 2005 to 1980. Hit the update button.

    • Even with wamba’s coaching, it will be amusing to see if DA can navigate his way back to the 1980 data.

      And toggle to show it as aggregate world data.

  15. Horatio Algeranon

    “The CO2 Harebrain Fraction”
    — by Horatio Algeranon

    The harebrain fraction of CO2
    Is on the increase, this is true

    The partial pressure in the brain
    That makes a person go insane —

    Think the CO2 amassing
    Is simply due to oceans gassing

    Believe that upward trends are down
    And act just like a circus clown.

  16. Dave Andrews

    Ok, lets look at some real figures.

    For coal alone both the EIA and the World Coal Association broadly agree that consumption rose from 5.3 billion tons in 1990 to 6.8 billion tons in 2009
    This is a 22% increase.

    The Mauna Loa figures show that over the same period atmospheric CO2 concentration increased from 350ppm to 390ppm – a rise of less than 12%.

    Remember too that oil consumption and gas consumption has also grown over this period, the latter quite spectacularly recently. These activities also cause CO2 emissions on top of those from coal consumption.

    It is clear that the Mauna Loa figures do not reflect this growth.

    [Response: I could have saved you even more embarrassment by deleting this comment.

    Do you not get the fact that emissions are related to the *growth rate* of CO2, not to its absolute concentration? Comparing the 22% increase in coal consumption to the 12% increase in CO2 concentration is — there’s no polite way to tell the truth about this — idiotic.

    You should have taken Abe Lincoln’s advice: Better to remain silent and be thought a fool than to speak out and remove all doubt.

    P.S. The figures I used are just as “real” and your implication otherwise is mighty snide (as well as false).]

    • Good grief. I think even as a child of seven, when I received pocket money, I would have been able to appreciate that if Daddy increased my weekly allowance from 53 pennies (ok, cents for you guys) to 68 pennies over a period of 19 weeks, and I noticed the contents of my piggy bank had only increased by 12% in the same period, I would have been able to work out that i) the increase in weekly pocket money was 28%, not 22%, and ii) to expect a 22% (or 28%, take your pick) increase in my piggy bank as a result would have demonstrated such an abysmal lack of understanding that Daddy would have been quite justified in stopping my pocket money for the rest of the year.

      We really do seem to be witnessing an aberrant form of mental functioning whereby the settled determination to deny the reality of AGW admits a bizarre illogicality into those afflicted. Is this the way the world ends, with humans reduced to arrant stupidity? For goodness sake, Dave Andrews, go and take cold shower, or at least keep your nonsense to yourself.

    • Spectacular logic fail, as Tamino points out.

  17. Dave Andrews seems to be an alarmist who denies that any of the CO2 in the atmosphere has a natural source … he apparently believes that there was 0 ppm CO2, rather than about 280 ppm CO2, in the atmosphere until we started burning fossil fuels.

    Pity the poor plants … there was no plant food at all in the atmosphere!


  18. Dave Andrews

    Lies, lies and damned statistics

    • Ray Ladbury

      Any damn fool can lie with statistics. What takes skill is using them to bring out the truth. But then truth has never been an interest of yours.

  19. I don’t know if any figures exist for it but here in Eastern Australia we’ve had a year of above average rain (la Nina) after years of drought that included widespread serious fires and these have to result in big regional swings in CO2 emissions and sequestration by vegetation; after years of natural sinks giving off CO2 we have a period when these are absorbing it via prolific plant growth. (Not permanent and I suspect not enough to wholly balance – I suspect an overall loss from vegetation in Australia from this ‘cycle’. If someone has links to relevant material I’d be pleased to take a look.) Similar variations undoubtedly occur around the world.

    As is SOP, graphs of CO2 levels are presented by deniers without wider context in order to strengthen the false argument that CO2 levels aren’t precisely following emissions, warming isn’t precisely following CO2 levels and therefore the link between CO2 and warming isn’t clear. Given broader context and understanding the argument collapses like the house of cards it is – or should with capable journalists working within media that put the importance of accuracy and truth above the agendas of their management.

  20. Shorter Dave Andrews:
    “It’s only a flesh wound!”

  21. @Dave Andrews:

    You’re right – the percent growth rates are wildly different!! You should make your quantitative argument a bit more rigorous, and submit it to WUWT. It should be published – of course – and Anthony loves this kind of argument. You would be doing him and the skeptic community a service.

  22. Dave Andrews


    I’m not the alarmist, you are. Strange how you accept there is a natural source of CO2 but won’t accept that there is a natural increase in temperature coming out of the LIA.

    Moreover Tamino’s argument about the rate of growth of CO2 and emissions is nonsensical given that the latter, as shown by consumption, has increased dramatically since 1990 but this does not show up in the Mauna Loa figures

    [Response: We were amused by your truly extraordinary lack of comprehension. Really, it’s dazzling.

    But now you’ve gone past amusing, to the point of pathetic; it’s so sad that it’s no longer funny. And since this blog isn’t about your kind of lunacy except as the occasional freak show … let us draw the curtain of charity over the rest of the scene.]

    • DA’s foolishness was amusing. . . but I do suppose that over-indulging would, as Heinlein said, “Get your soul all sticky.”

    • Rob Honeycutt

      Dave… Even coming out of the LIA you have to have a mechanism for the warming. You can’t just say, “Oh, look the trend is up since then so this is natural.” That’s just sticking you fingers in your ears and saying, “La la la la…”

      What is compelling is that there are so many natural mechanism that would be causing cooling today (Milankovitch cycles, etc [see Miller 2010]) and yet we are seeing such a profound warming trend.

  23. Dave Andrews:

    Lies, lies and damned statistics

    Hmm, plagiarism isn’t a convincing rebuttal …

  24. > a 22% increase….
    > a rise of less than 12%.
    Well, duh. That’s about right, biological processes and solubility in the ocean have been handling some–not all–of the fossil fuel carbon.
    Factor in ocean pH change yet?

    [Response: The real folly is comparing an increase in *emissions* to an increase in *total atmospheric CO2*. It’s nonsense.]

    • Yep. Those who, like DA, can’t distinguish principal from interest really should get a good financial advisor.

    • TrueSceptic


      I’ve read many excellent posts from you and I can’t believe that you appear not to understand the level of Dave Andrews’s incompetence.

      Firstly, he can’t even calculate a simple percentage. 6.8/5.3 = 1.283, i.e., an increase of 28.3%, not 22%. Somehow, he gets the other one right, though: 390/350 = 1.114, i.e., an increase of 11.4%, which is indeed “less than 12%”.

      He seems to think that the total CO2 ppm at any point should be proportional to the annual CO2 emissions. He’s not only trying to compare a total with an increase, he’s also ignoring the ~280 ppm “natural background” level. If we subtract that from each total, we get an increase of anthro CO2 from 70 to 110, an increase of 57.1% (110/70 = 1.571), a much greater increase than 28% (which is coal-only but was presumably chosen to be representative of all fossil fuel consumption), so his claim is destroyed even using his own “logic”.

      But that’s rubbish anyway because we are still confusing increases with totals. In 1990 the annual CO2 ppm increase was around 1.3. Extrapolate that to 2009 using just the coal figures and we get 1.3 * 6.8/5.3 = 1.7. If anything, the real annual increase was greater than that, so again DA’s claim is destroyed.

      Even ignoring DA’s lack of understanding, what was he getting at? That the CO2 figures are too low? In one sense they are, because only about 1/2 of “our” CO2 stays in the atmosphere, but he doesn’t even seem to be aware of that.

  25. t_p_hamilton

    Dave Andrews:

    Lies, lies and damned statistics


    Hmm, plagiarism isn’t a convincing rebuttal …

    Dave Andrews can’t even get plagiarism right.

  26. Why waste your time on this poor soul when there is cool science out there? Look back at my earlier post. Anything newer out there than Le Quéré et al.? Something that deals in an interesting way with the S Ocean? This, after all, is where you all can shine. Stop abusing the troll! T’aint droll.

    [Response: I noticed your comment — with links well worth following — and I appreciate it.

    But don’t blame me for the troll. I didn’t invite him here. As for the abuse, he invited that on himself. In my opinion, I was more merciful than he deserved.]

  27. Check out my web page on Alexander Cockburn:

    Where I explain Dave’s type of fallacy in depth. Cockburn, too, seems to think the airborne level of CO2 is directly proportional to human emissions, to the point where he thinks it would fall if our emissions decreased. Not go up more slowly, you understand, but actually fall.

  28. Well put. At what point do we consider this an airborne toxic event? I enjoy using the World Bank per capita emission data base for nations to compare graphically provided by Google I notice that this term that I have used in class has now been taken up by a band

  29. indeed. but others are piling on – the horse needs no more beating!


    “Photosynthesis by phytoplankton in sunlit surface waters transforms inorganic carbon and nutrients into organic matter, a portion of which is subsequently transported vertically through the water column by the process known as the biological carbon pump (BCP). The BCP sustains the steep vertical gradient in total dissolved carbon, thereby contributing to net carbon sequestration. Any changes in the vertical transportation of the organic matter as a result of future climate variations will directly affect surface ocean carbon dioxide (CO 2) concentrations, and subsequently influence oceanic uptake of atmospheric CO 2 and climate. Here we present results of experiments designed to investigate the potential effects of ocean acidification and warming on the BCP. ….. The elevated CO 2 and temperature treatments disproportionately enhanced the ratio of dissolved organic carbon (DOC) production to particulate organic carbon (POC) production, whereas the total organic carbon (TOC) production remained relatively constant under all conditions tested. A greater partitioning of organic carbon into the DOC pool indicated a shift in the organic carbon flow from the particulate to dissolved forms, which may affect the major pathways involved in organic carbon export and sequestration under future ocean conditions.”

  31. Yeah. That’s a neat paper. The dual impact on the biological carbon pump and the changes in Revelle factors are interesting to compare. As buffer factors decrease, with CO2 dissolution, local variations in seawater pH and dissolved inorganic C are going to play a larger role in what happens to the rate of the ocean sink. Seasonal and inter-annual variability will increase even as the efficacy of the sink decreases globally. Add changes to the biological carbon pump (e.g., above) and the ocean sink seems like something we shouldn’t treat as a static factor.

  32. I’m a bit confused on the airborne fraction. According to Global Carbon Budget ( ) “Natural land and ocean CO2 sinks removed 57% of all CO2 emitted from human activities during the 1958-2009, each sink in roughly equal proportion. During this period, the size of the natural sinks has grown almost at the same pace as the growth in emissions, although year-to-year variability is large.”
    That would mean ~45% remains arborne not ~55%. What am I missing?

  33. The 55/45 split often gets reversed.
    It’s my understanding that the ~55% is what is absorbed while the ~45% constitutes the airborne fraction.

    [Response: I don’t think so. Using data since 1980, the mean airborne fraction comes out to be 57%.

    Perhaps the confusion arises because airborne fraction has increased over time, but the increase is not noticeable since 1980 but is noticeable since 1958. Certainly the annual increment in CO2 has increased (considerably!) over that time.]

  34. Here is the data used by Global Carbon Budget.

  35. I’ll take your word for it, Tamino, since if anyone would know how to calculate it it’s you, but I see the two reversed all the time in reputable sources and it sure would be nice if it were used consistently.

    [Response: It appears I was mistaken. The previous comment points to carbon-budget data, which indicates that my estimate is higher because it omits CO2 emission from land-use changes. According to that data, ignoring land-use change the airborne fraction is about 56%, but when land-use change is accounted for it’s only 44%. Also, I don’t see any trend in the airborne fraction since 1959.]

  36. Alexander Harvey

    Your graphs seem to be out by 2 years e.g. the (1998-1997) difference is plotted above 1999.5


  37. Quick question for any experts out there – if the atmosphere is pushing out due to increased temps, then can we convert MTons of emission to ppmv accurately? Put another way, did 7800 Mt CO2 = 1 ppmv in 1900 *and* 1990, or should that “equivalence” also decrease as temps increase?

    [Response: Thermal expansion of the atmosphere has no effect on the *number* of molecules.]

    • A nitpick would be that the atmosphere isn’t “pushing out,” either. The troposphere may be warming but the stratosphere is cooling. Thermosphere, too, IIRC, and–going out on a shaky limb here–I also seem to recall that that’s a function mostly of solar activity.

      Corrections welcome. . .

  38. Tamino: “According to that data, ignoring land-use change the airborne fraction is about 56%, but when land-use change is accounted for it’s only 44%.”

    Ah, so this distinction could explain the reversed ratios in reputable sources then.