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Volcanic vs. Anthropogenic CO2

Filed under: — group @ 4 August 2011

Guest Commentary by Terry Gerlach*

TV screen images of erupting and exploding volcanoes spewing forth emissions are typically spectacular, awesome, and vividly suggestive of huge additions of gas to the atmosphere. By comparison, the smokestack and exhaust pipe venting of anthropogenic emissions is comparatively unexciting, unimpressive, and commonplace. Consequently, it easy to get traction with the general public for claims that volcanic CO2 emissions are far greater than those of human activities, or that the CO2 released in some recent or ongoing eruption exceeds anthropogenic releases in all of human history, or that the threat of a future super-eruption makes concerns about our carbon footprint laughable. The evidence from volcanology, however, does not support these claims.

Volcanic plume ** V Fossil fuel plumes**

My article “Volcanic Versus Anthropogenic Carbon Dioxide” appeared in the June 14 issue of the American Geophysical Union’s publication Eos and addresses the widespread mis-perception in the media, the blogosphere, and much of the climate skeptic literature that volcanic CO2 emissions greatly exceed anthropogenic CO2 emissions. I wrote the article to provide a comprehensive overview of the topic using only published peer-reviewed data with a minimum of technical jargon for a broad spectrum of Earth science researchers and educators, students, policy makers, the media, and the general public. AGU has made the article public; anyone can download a copy. There is also an Eos online supplement, although I have a better formatted pdf version that is available upon request.

The bottom line? Annual anthropogenic CO2 emissions exceed annual volcanic CO2 by two orders of magnitude, and probably exceed the CO2 output of one or more super-eruptions***. Thus there is no scientific basis for using volcanic CO2 emissions as an excuse for failing to manage humanity’s carbon footprint.

*Terry Gerlach is retired from the U.S. Geological Survey where he was a volcanic gas geochemist.The views expressed are his own.
** Yes we are aware that CO2 is colorless and that the plumes in the figures are mostly steam. – Eds.
***Super-eruptions are extremely rare, with recurrence intervals of 100,000–200,000 years; none have occurred historically, the most recent examples being Indonesia’s Toba volcano, which erupted 74,000 years ago, and the United States’ Yellowstone caldera, which erupted 2 million years ago.

115 Responses to “Volcanic vs. Anthropogenic CO2”

  1. 51
    DP says:

    I am confused here. I here that volcanos cool the planet due to sending dust in to the upper atmosphere, and a really big eruption could send us in to something like a nuclear winter. Now they are warming agents. Which is it?

  2. 52
    Titus says:

    Not a Wikipedia fan, however, this looks an interesting limk to my previous comment:

  3. 53
    Clippo (UK) says:

    re:- #50, Jim eager

    I apologise for being late to the party but I didn’t see EFS_juniors reference to Salby before I posted. As for the wrong thread, Que?, – this is about CO2 emissions & recent rises is it not?
    (and my opening words, “Hiding a smirk” meant that I consider Salby’s opinions a load of rubbish).

  4. 54
    Clippo (UK) says:

    Re Jim Eager

    Further apologies, I have now just discovered this was discussed in Unforced Variations – I simply don’t have time to read every post in every thread.

  5. 55
    Lynn Vincentnathan says:

    My answer to the CO2 from volcanoes (as a non scientist, who can’t answer with authority on the “science” the denialists bring up) is:

    “Then we have to REALLY reduce our GHG emissions a lot more, because you never know when a reall big volcano is going to emit CO2, and we just can’t have our human emissions added on to that, or it would be very bad for us. We can’t stop those volcanos (or the sun from shining, or the cosmic rays, etc), but be can and really must reduce our own GHG emissions, and even more so now that you’ve brought up these other contributions to global warming that are beyond our control.”

    And as for #49 and “warming causes CO2 [and CH4] emissions from nature” — similar answer:

    “Now that’s really scary, that warming releases GHGs, which, of course, does not disprove that GHG cause warming (which is well known), so in that case we REALLY have to reduce our GHGs way down, more than what everyone’s saying, because we just can have a situation in which the little warming we cause then causes release of GHGs from nature, causing more warming, causing more release, causing …. total doom. We just can’t have that!”

    P.S. I’ve read that volcanoes (near massive coal formations), the Siberian traps, probably played a role in triggering the end-Permian great warming 251 mya that killed off more than 90% of life on earth…but I think over a much longer period than our human spewing of GHGs into the atmosphere. Also, that the great warming caused hydrogen sulfide formation and release, nearly wiping out what little life remained. And I think recently I read that the warming of ? 200 mya led to vast methane release which killed off a lot of life.

    What are we doing playing with matches in a dynamite storeroom?

  6. 56
    wili says:

    Thanks Slioch and Terry for the clarifications.

    Anyone have an accurate, sourced figures for CO2 equivalent anthropogenic annual emissions–that is a figure for all GHGs humans are directly responsible for emitting?

  7. 57
    Hank Roberts says:

    > Titus
    > Not a Wikipedia fan …

    You need to specify the day you refer to, as edit-war-prone climate-related articles change a lot.

    Peiser’s long been calling attention to catastrophes as possibilities affecting climate; arguments occur about the details of events.

  8. 58
    Hank Roberts says:

    PS for Titus, down at the very bottom of that Wikipedia page, it points to:

    “retrievals fortatv” says the ReCaptcha oracle.

  9. 59
    Jim Harrison says:

    The language probably works for the readers of a publication like EOS, but if you get a chance to make the same points in a publication for the general public, I’d advise against talking about “orders of magnitude.” Most people don’t really know what an order of magnitude actually means, any more than they get exponential notation.

    The terminology that throws people is not always obvious. Experienced journalists always talk about the eighteen hundreds instead of the 19th Century, for example, but it took me a while to realize why.

  10. 60
    Hank Roberts says:

    For wili, who asks for help, wondering if anyone knows

    First result of the search:

    AR4 SYR Synthesis Report – 2.1 Emissions of long-lived GHGs
    (a) Global annual emissions of anthropogenic GHGs from 1970 to 2004. … Carbon dioxide-equivalent (CO2-eq) emissions and concentrations …

  11. 61
    Farmer says:

    “climate skeptic literature” — there are skeptics of climate?!

  12. 62
    Slioch says:

    #37 Terry Gerlach

    Thanks for those comments on the BGS article.
    I had rather taken it that the 0.3 GtCO2/year does include the submarine contribution, and is a rough summation of the contributions given in Fig.2, rather than the reference to 300 Mt/year on page 1, but, like you, I don’t find it at all clear.

    [Fig. 2 gives 66-97 Mt CO2/year for mid-ocean ridges, 80-132 Mt CO2/year for hotspots and 66-135 Mt CO2/year for subduction related volcanism, but the text mentions that Morner and Etiope (2002) consider that hydrothermal alteration of the newly erupted lavas at mid-ocean ridges absorbs as much CO2 as the eruptions emit, so that the net atmospheric emissions of CO2 from that source are close to zero.]

    However, at the level of general take-home message the BGS article does agree that volcanoes are emitting to the atmosphere less than 1% of the CO2 that humans are producing, and that is the main message that needs to be got across.

  13. 63
    John Mayer says:

    A simple question, but one I’ve not found the answer to in my searches: has the North Pole itself been ice-free yet? I know an endurance swimmer swam very near the ice pole in 2007, but has the pole itself yet been free of ice. I ask because of the symbolism attached to the north pole.

  14. 64
    Meow says:

    @55: See . Also:

    The EIA says coal-burning added 13,394 MT CO2 (= 3,653 MT C) in 2009.

    And the CDIAC estimates coal-burning added 3,392 MT C in 2009.

    The EIA says oil-burning added 10,888 MT CO2 (= 2,969 MT C) in 2009.

    And the CDIAC estimates liquid-fuel burning (mostly oil?) added 3,019 MT C in 2009.

    The EIA says natural gas-burning added 6,032 MT CO2 (= 1,645 MT C) in 2009.

    And the CDIAC estimates natural-gas burning added 1,553 MT C in 2009.

    By EIA figures, we added ~8,267 MT C in 2009 solely from burning fossil fuels. And by CIADC estimates, it’s 7,964 MT. CIADC also estimates cement manufacture at 381 MT and gas flaring at 54 MT. Neither figure includes emissions from land-use changes or feedbacks.

    You could SWAG land-use change and feedback figures, then cross-check the results with CO2’s airborne fraction, but since that number seems to vary a great deal year-to-year, I’m not sure what it would mean.

    CAPTCHA: suspi rainee

  15. 65
    Dominik Lenné says:

    That’s all well and good – we humans are much better in CO2ing our air than good old volcanoes are. But the other side is at least as interesting: their emission of light-reflecting matter like sulfur and ashes and so forth.
    I would be interested in whether these balance volcanic CO2 more or less.

  16. 66
    Slioch says:

    #63 Domimik Lenne

    Balance? No. see fig.a under “Effective Forcings Employed in Current Climate Simulations” here:
    The “stratospheric aerosols”, grey line, are the volcanic aerosols of which you speak. They are short-lived and intense, increased CO2 is slow, relentless and long-lasting.

  17. 67
    Hank Roberts says:

    > Dominik Lenné
    asks whether
    > [volcanic] sulfur and ashes … balance volcanic CO2

    Briefly, for a year or two; see paleo records from before humans came along.

    A large volcanic eruption can produce a year or several years of cooling.
    Sulfate and ash fall out of the atmosphere over a few years’ time.

    Any pulse of CO2 persists in the atmosphere far longer.

  18. 68
    Pete Dunkelberg says:

    Dominik Lenné @ 63, the occasional major eruption has a distinct cooling effect (look up :the year without a summer) but this is part of the normal background noise, superimposed on the trend but a trend is still a trend.

    note the graphs (scroll down to see them all)

  19. 69
    Pete Dunkelberg says:

    Those gray down-spikes are due to volcanoes.

  20. 70
    One Anonymous Bloke says:

    Dominic Lenne #63 The aerosol cooling effect you describe lasts for 1-3 years or so, and reduces temperature considerably more than the volcanic CO2 raises it.

  21. 71


    Nicely done, Lynn, and much to the point, really.

  22. 72
    Pete Helseth says:

    On the topic in #63 – #68, please also see Solomon et al.:

    “Several independent data sets show that stratospheric aerosols increased in abundance since 2000. Near-global satellite aerosol data imply a negative radiative forcing due to stratospheric aerosol changes over this period of about –0.1 W/m2, reducing the recent global warming that would otherwise have occurred. Observations from earlier periods are limited but suggest an additional negative radiative forcing of about –0.1 W/m2 from 1960 to 1990.”


    Science DOI: 10.1126/science.1206027

    From Science’s RSS descriptive tag for this article: “A thickened stratospheric haze has been counteracting global warming, but it won’t last”

    (Posted by a non-scientist who’s merely trying to stay current with your conversation; thanks).

  23. 73
    Jesús R. says:

    #72, that paper has reminded me of this one:

    “it has been unclear why global surface temperatures did not rise between 1998 and 2008. We find that this hiatus in warming coincides with a period of little increase in the sum of anthropogenic and natural forcings. Declining solar insolation as part of a normal eleven-year cycle, and a cyclical change from an El Nino to a La Nina dominate our measure of anthropogenic effects because rapid growth in short-lived sulfur emissions partially offsets rising greenhouse gas concentrations”

    Kaufmann et al 2011

    Reported by BBC as “Global warming lull down to China’s coal growth “.

    [Response: The trouble with that paper is that it addresses a non-question. See e.g. Richard Black’s commentary here: for why claiming ‘no warming since 1998’ is just silly. See also Stoat’s amusing take on this.–eric]

  24. 74
    Jesús R. says:

    Thanks for your answer, Eric. I perfectly understand that we cannot statistically say that there’s any pause in the warming trend (especially since the Kaufmann et al paper just focus on surface temperatures). However, regardless of that, I think that these two papers estimate that there is a slight slowdown in net antrhopogenic radiative forcing:

    The Kaufmann paper says:
    “Because of the resultant increase in anthropogenic sulfur emissions, there is a 0.06 W∕m2 (absolute) increase in their cooling effect since 2002 (Fig. 1). This increase partly reverses a period of declining sulfur emissions that had a warming effect of 0.19 W∕m2 between 1990 and 2002.

    The increase in sulfur emissions slows the increase in radiative forcing due to rising greenhouse gas concentrations (Fig. 1). Net anthropogenic forcing rises 0.13 W∕m2 between 2002 and 2007, which is smaller than the 0.24 W∕m2 rise between 1997 and 2002.”

    And the Solomon et al paper mentioned in #72 estimate “a negative radiative forcing due to stratospheric aerosol changes over this period of about –0.1 W/m2“.

    So I think that, regardless of what statistics tell us about recent trends, both papers are pointing to a somewhat relevant role of sulfur emissions in slowing recent net antrhopogenic forcing, which I think is something new, and therefore, potentially interesting. I say “potentially” because I don’t know whether this new stuff is relevant (should this trend in sulfur emissions continue, I don’t really know whether it would have any relevant impact on warming projections).

    [Response: Yup, fair enough. My objection was to the silliness of the way Kaufmann and others introduce their work, not to the details of the work itself, which seems fine. –eric]

  25. 75
    Gsaun039 says:

    This caught my eye in Comment 26:
    Plimer states: “Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere. One volcanic cough can do this in a day.”

    For the mathematically challenged, thats 10 parts per 100,000 and 100 parts per million…just about what humans have added over the course of the past 250 years during the industrial revolution if you accept, as I do, the per-industrial atmospheric concentration of CO2 at ~280 ppm.

    The problem with Plimer’s assertion is that even if the volcanic gas released was 100% CO2 and was treated as a supercritical fluid prior to release from the crust, from a sufficiently large vent, the supersonic velocities needed to be attained (and the local impacts associated with such a supersonic jet) defy physics, at least on the scale of a single day.

    Talk about fire and ice. The ice storm, not to mention the dry ice storm, would be of an unprecedented nature…think large scale CO2 fire extinguisher. Add to that the huge dead zone because of local anoxic conditions. That CO2 does not instantly and uniformly distribute itself through the vertical column of air nor across the spatial surface area of the planet.

    As an offhand remark, its a way to dismiss human impact or to give some “credibility” to the idea that conditions have been like this before. But I doubt Plimer can point to any single event in the recent geological past that has had this effect.

    And my question to anyone who takes this line that it not only can happen but has happened before is this: “How did the 7 billion people living on the planet fare the last time this happened?”

  26. 76
    ozajh says:

    John Mayer #63,

    IMHO this question should also be posted in the ‘Unforced Variations’ thread, but I’ll attempt a layman’s answer. (Any scientists please feel free to correct me.)

    On the micro scale (up to a few hectares, perhaps??), there would almost certainly have been occasions when there was a lead or polynya open at the North Pole.

    On the macro scale, I suspect the answer is ‘No’.

  27. 77
    ozajh says:

    Errrr, that was ‘No’ as in ‘not in the last few thousand years’.

  28. 78
    Terry Gerlach says:

    #59 (Jim)
    Thank you for the suggestions and advice.

    #62 (Slioch)
    In fact, there are offsets for all of global volcanic CO2 emissions (not just the mid-oceanic ridge source) because the long-term carbon cycle is well balanced. Over a thousands-of-years timescale, all volcanic CO2 emissions are offset by silicate weathering and alteration of continental and oceanic crust, carbonate deposition, and organic carbon burial. So there is no net buildup of climate-forcing CO2 in the atmosphere from volcanoes, provided long-term carbon cycle balance is maintained.

    This is Hans’s point (#13) that, in this context, volcanic CO2 emissions have “no meaning.” But climate skeptics could argue that over shorter timescales the carbon cycle may not be well balanced and volcanic CO2 may dominate anthropogenic emissions. For this reason, I prefer to simply sum up volcanic CO2 emissions and confront them with the numbers to underscore that the probability of volcanic CO2 dominating anthropogenic CO2 year after year for during the past century is very small, even without considering offsetting carbon cycle processes.

    Terry Gerlach

  29. 79
    Clif Westin says:

    I remember watching documentary years ago about the Permian Die off called “The Day the Earth Nearly Died” (link below). The title is a bit misleading in that; it took a bit longer than a day. It starts off looking at an asteroid as the cause of the die off but moves on to the Siberian Traps.

    This Documentary had a Scientist, Paul Wignall, go to Iceland and look at the rocks from the Permian period and he found that global warming had taken approximately 40 thousand years of co2 releases from the volcanos of the Siberian Traps to lift global temperatures 4 to 5 degrees c. He went on to say that was enough to warm the oceans and allow methane hydrates to evaporate and release from the oceans to push it up another 5 degrees to kill nearly everything (total of about 80,000 years).

    My understanding of the Siberian Traps volcanos leads me to believe that they were releasing far more co2 (100,000 gigatons of carbon) than we do (8 gigatons annually) and for it to take 40,000 years of that kind of a release to lift global temperatures 4-5c means, well, we couldn’t possibly repeat that trick with our current release levels.

    What was a bit unclear is from the documentary is when his timeline starts, at the beginning of the Siberian event, middle, end; he doesn’t say.

    Anyway, it comes down to this, it took 40,000 years to raise the temperature 4-5 c at co2 release level epically larger than ours. I just don’t see how the IPCC could figure we would raise temperatures 1c in 100 years with our current release levels.

    Video embedded on this page:


  30. 80
    Michael J says:

    Possible dumb question (from possibly dumb reader – me)

    The EOS piece talks a lot about estimates. I guess that is not surprising as some of these things are pretty hard to measure.

    My question is: how reliable are the estimates?

    What are they based on? How do you estimate the CO2 from a volcano? From every volcano? Do we even know how many undersea volcanoes exist?

    How do we estimate human CO2 emissions?

    These are not rhetorical questions. I would really like to know.

  31. 81
    Pete Dunkelberg says:

    Human CO2 emissions are estimated from direct measurement of incre3asing concentration and C13 / C12 comparisons, and from knowing how much carbon we burn.

    Volcanic CO2 is reliably estimated to be a tiny fraction of this from the fact that if were anywhere near as high as CO2 produced by the carbon we burn, much 100 times as much as very dense types say, we would have been cooked before we ever evolved. We exist therefore volcanic CO2 is low.

    Oh, and for volcanic CO2 to have been similar to ours throughout earth’s history, the atmosphere would need to be far heavier than it is and the seas would be acid.

  32. 82
    EFS_Junior says:

    #80 … estimates … estimates … estimate … estimate …

    Do you, a priori, have a basic problem with estimates? Other than repetition of said word?

    For CO2 estimates, see, for example, the IEA;

    or the EPA (for USA);

    If you don’t trust those estimates, I’d suggest that you make up your own estimates, and get your estimates published in E&E. I estimate, with p = 1.0, that E&E would gladly publish your made up estimates.

  33. 83
    Michael J says:

    #82 (and #81)

    I don’t distrust the estimates, but I don’t (yet) know if I can trust them. If they are reliable, then that probably means they were computed from some reliable data using a reliable algorithm. I would like to know what data and what algorithm.

    e.g. We might say
    – Americans consumed ‘n’ litres of gasoline last year
    – Each ‘n’ litres of gasoline produces ‘n’ Kg of CO2
    – Therefore we know that ‘n’ Kg of CO2 was produced.

    Repeat for every major source of CO2, in every country, and we can make a pretty good estimate of human-produced CO2.

    Now that was just speculation. The actual method might be quite different. But I would like to know how we come up with the estimates for human and volcanic CO2 emissions.

    [Response: The back-of-the-envelope suggestion you make is of course done all the time to check on whether the more complete results done by someone else pass the ‘sniff test’ of reliability. Try it. The data are not hard to find. You’ll discover it is impossible for the essential point — that people completely overwhelm volcanoes — to be wrong. After that, it is just details (does it really matter if volcanoes contribute .1% vs. .2%?). And of course, that’s not even including the ancillary data (isotope ratios, etc. etc.).–eric]

  34. 84
    Michael J says:

    #82 – By the way, who is E&E?

    [Response: Energy and Environment, a not-actually-peer-reviewed journal.–eric]

  35. 85
    Michael J says:

    Hi Eric

    I don’t really have the time to redo the calculations. Truth be told, nor the inclination. Certainly to do it the way I suggested above would (I suspect) take a great deal of time, tracking down all the CO2 sources and their world-wide usage.

    The EOS article mentioned in the original post quotes a bunch of CO2 estimates to illustrate why human CO2 dwarfs Volcanic CO2. If the estimates are reliable, then the author has a very strong argument.

    The numbers are just quoted without any source info (unless I missed it). Now that may be because everybody (except me) already knows that they’re reliable. However for my own assurance, I would love to see a paper or article explaining how the estimates are produced — thus giving me confidence that they are reliable.

    Sorry if I’m repeating myself, but I’m just trying to follow this through. :-)

  36. 86
    EFS_Junior says:


    First, RTFM!

    That means read the effin’ paper and supplimentary materials that are the subject of this thread, there are references to the relevant CO2 estimates for anthropogenic and volcanic emissions, how those estimates were made, etceteras.

    Second, one pillar of the scientific method is falsification, that means you will need to put up or shut up, by means of citing from the well respected peer reviewed climate science literature, that directly counter, with evidence, the numbers cited here for CO2 emissions from volcanic and anthropogenic sources.

    Third, I provided links to the IEA and EPA, methodologies and uncertainties are explicitly covered in both of those reference locations, see also, for instance, this IEA workshop titled “IEA Energy Statistics Co-operation”;

    Fourth, do your own research and then publish your own results in the well respected peer reviewed climate science literature (NOTE: E&E is most definitely NOT in that group).


  37. 87
    Mitch Lyle says:

    I think it is worth quoting the other part of the Gerlach paper about marine volcano emissions of CO2. Current estimates of total ocean basalt production are about 3 square km per year. if CO2 emissions from under the ocean were to match fossil fuel CO2 emissions, the CO2 emissions would be the same as the total mass of basalt production. This is clearly wrong–way too much CO2.

    It might be possible to argue that the volcanic CO2 emissions vary by a factor of two or so, but that is still ~100 times less than humans.

  38. 88
    Michael J says:

    #86 – EFS_Junior

    I’ve clearly said something that you find offensive and I apologise for that. My intention was not to cause any harm.

    1. RTFM
    I did read the paper which was quite short. It contained many estimates, but no information about how they were arrived at.
    I didn’t read the supplemental material. (My bad).
    I’ve just read that now. It mentions CO2/3He ratios for estimating volcanic CO2. I will investigate further and try to find an explanation of how that works, if nobody here can tell me.

    2. Falsification
    I haven’t proposed any new information so it would be impossible for me to propose falsifying anything. That makes no sense.

    3. IEA and EPA
    I did quickly read the links you gave me and did not spot anything helpful. If you know they contain the information on how to compute CO2 estimates, could you please point out where?
    The new link from your last comment was a bit more helpful. It has some conversion factors for burning fossil fuels, g(CO2) per kWh. Unfortunately I still don’t know how to estimate the kWh of all the different fuel types, world-wide.

    4. Publishing
    I have no research, I am just trying to understand Mr Gerlach’s research. (Should that be Dr Gerlach?)

    I do not understand why you are so hostile to somebody asking questions. You act like I am asserting that Mr Gerlach is wrong. I am doing no such thing. I’m just trying to understand it better.

    It may be that everybody here is so familiar with CO2 emission estimates that my question seems foolish — but for me it is a valid question.

  39. 89
    jkga says:

    #88 – Michael J
    In the EPA report, the methodological details are given in the “Annex” sections at the bottom. The last one, Annex 7, which is all about quantifying the uncertainty in the estimates, might be of particular interest to you.

  40. 90
    JG_in_SoCal says:

    Re #88 — understandable response to #86. Shrug off the nonsense and keep looking for the truth. It is clear you will need to do some homework (perhaps much some consider remedial, but so be it – we all start at the bottom). It may be a few years worth given the time you may have available for it, and how far you may have to go, but time well worth investing. I know from an analogous experience: I transitioned by personal interest a few years ago from a long career in physical science to medical science with interest in glucose monitoring. It ended up requiring 3 years attending scientific conferences with MDs and clinicians using words, terms and concepts I had never heard of or considered and biochemical names and process so long and complex they seemed barely comprehensible. My investment has provided me at least two things of great value: (1) I now do (at least what I my colleagues consider) significant development in that field and (2) what I learned has changed my whole attitude toward food, behavior and lifestyle. I learned what diabetes is on a personal level from testimony of those who live with Type 1 and desperately want a cure. I learned how Type 2 diabetes develops from inattention to diet, lifestyle and behavior. I learned what a terrible life changer it is to have to inject oneself with insulin daily and to prick one’s finger every few hours just to make sure you stay alive. Analogies to global climate change aside, my point of all this is simply that spending a few years studying climate science and understanding its underpinnings, its methodologies (physics and math) and its impact on our collective and individual lives and future is well worth the investment and will likely change how you view and value your life and lifestyle and of those around you.

  41. 91
    Jim Eager says:

    Michael J, annual world-wide production figures for coal, oil and natural gas are readily available. The stuff isn’t stockpiled for a rainy day, it pretty much all gets burned in the year it’s produced, so annual consumption figures pretty well match annual production figures. Although undoubtedly not precise, they will not be off by much, certainly no where even near by an order of magnitude (factor of 10). Converting those figures into emitted CO2 based on the carbon content of each fuel is therefore a simple multiplication exercise and people do indeed make that calculation. So, calculating annual emissions of CO2 from the burning of fossil fuels is pretty straightforward. Add to that the measured proportional decline in atmospheric O2 (molecular oxygen) in lock step with the increase in CO2 and it is abundantly clear that the increase is the result of the combustion of carbon.

    Volcanic emissions of CO2, on the other hand, are far less constrained and thus less exact, but are still clearly two orders of magnitude smaller (a factor of 100). They are based on physical sampling of the gasses in actual eruption clouds (most of which by far is good-old H2O), magma and rock samples, and samples of deep sea rock and water in extrusion zones. As Mitch said, even if off by a factor of 2, or even 4, volcanic emissions would still be two orders of magnitude (factor of 100) lower than human emissions.

    It really is a slam-dunk.

  42. 92
    Meow says:

    @88 etc.: A very rough estimate of anthro emissions from fossil fuel burning takes a few hours. You can find figures on estimated production, consumption, and emissions from major fossil fuels here. To get from the consumption to emissions figures, you need to do things like estimate what proportion of the fuel in question is eventually burned and how much of it is carbon. This is not always straightforward. For example, you need to know whether the consumption figure for coal is of raw coal, washed coal, or washed and dried coal. It makes a big difference, because raw coal can contain ~13% moisture and 12% “ash” (clay, etc.). Similarly for natural gas, which isn’t all CH4, and whose industry-standard measure (“cubic feet” — ha!) needs to be converted into something useful, like moles of carbon.

    I haven’t tried a back-of-the-envelope calculation for anthro CO2 emissions from land-use changes, which has got to be much more difficult than for fossil fuel burning. You could examine how the IPCC estimated total anthro CO2 emissions, which has cites to all its sources.

    As to source reliability, you can at least cross-check multiple sources (for example, this is an alternative to EIA’s coal stats). You could also estimate coal production by examining shippers’ stats (e.g., railroad and surface ship), and consumption by examining electric utility and steel producer stats.

    CAPTCHA: W-algebra urpfork

  43. 93
    Michael J says:

    #89, 90 and 91 – Thanks for taking the time to make constructive replies. You have given me quite a bit to digest. I don’t want to recompute every estimate, just to get a better feel for how the estimates are computed so I have a bit of confidence.

    If you look ’round the internet there are many people quoting estimates of CO2 and of many other things. Clearly they’re not all right. :-)

    Anyway, I’ve got some work to do.

  44. 94
    Randy Ross says:

    In reference to comment 79 on Permian rocks in Iceland.
    Iceland is very young, in geological terms. The oldest parts (according to are just listed as over 3 million years old.
    The Permian Extinction was over 200 million years ago.
    Iceland is definitely not the place to look for evidence of the Permian extinction.

  45. 95
    Hank Roberts says:

    > just listed as over 3 million years old.

    Looking into that, it says “older than 3 million years” in the caption here:

    The focus of the article Randy Ross quotes is on the volcanic rock that formed what we now call Iceland, not on the ocean sediments around it:
    “… the age of Iceland’s rocks and lava flows depend on their position on the island. Because of the sea-floor spreading, in the Northwest and in the East of Iceland rocks are older than along the Mid-Atlantic ridge which is situated in the middle. …”

    Elsewhere on the subject, I found

    “Paul Wignall from the University of Leeds in the UK examined the marine fossil record in Iceland from the Permian era.”

    I’d guess the confusion is because the marine sediments predate the relatively recent volcanos that form what we now call Iceland.

  46. 96
    indri says:

    @Michael J
    For all countries under the Kyoto Protocol there is a very strict reporting system with a lot of international reviews for each country.
    The yearly report for my country has more then 700 pages – I don’t think, you would like to read this ;).
    The greatest part of the emissions of CO2 is calculated from fossile fuels with conversion factors. But there are a lot of other emissions (eg. land use change, production of lime, use of solvents, incineration of waste) of CO2 and the other gases. You get not only sums but also emissions for different sources (traffic, households, industry…).

    Most fuels are standardized (you don’t want to buy fuel, that gives you less energy then what you paid for), so the conversion factor for a specific product is precisly known. The numbers are cross-checked with other methods (eg. energy needed to heat houses, energy per produced ton of steel, kms driven by cars and trucks).

    Under the Kyoto Protocol you can be quite sure, that no country will report to much CO2, because it will have to pay for the excess.

  47. 97
    JG_in_SoCal says:

    @ Michael J
    (and for what it is worth): I just did a 5 minute calculation – went to Wikipedia, found that world energy consumption is 5 TW (power) of which 85% is from carbon-based fuels (from graphs), which translates to ~ 40,000 Tw-hrs (energy; need hrs per year). Using a shortcut etimate I know in my head 33 KWhrs in 1 gallon gasoline (I own a Leaf!). Since within a factor of 2 or 3 carbon-based fuels are fairly equal when it comes to CO2 production and 1 gallon of gasoline produces about 20 lbs of CO2 (thank you Google), I calculate a human emission of 10^10 tons/yr (within a factor of 2 or 3). I then Googled volcanic CO2 production and got 2 x 10^8 tons/yr. So, to an order of magnitude (factor of 3 or so AND assuming I’ve done my arithmetic correctly) Human:natural = 100:2. Natural CO2 is only ~ 2% of the yearly production, which I believe is in line with what the more detailed calcualtions provide. It took longer to write up this text than to do the calculation. But, little mater since I’ve got some experience in such matters – you should consider the simple process by which I found the data and arrived at the result … and that I compared that result with more rigorous calculations. My conclusion is that the inferences drawn from rigorous calculations are worth considering. You now might want to study a bit about the CO2 iosoptic anomaly perspective to see what that says about how the ocean and biosphere transpire CO2. This task will bring you another step into realm of the complexity and wonder of our atmosphere.

  48. 98
    Terry Gerlach says:

    #79 (Clif Westin)
    I watched your video and skimmed through the transcript (thanks for providing these). Both sources say that Paul Wignall did his fieldwork in Greenland, not Iceland (as your post states). This unfortunate error misled Randy Ross and Hank Roberts to make ‘false alarm’ posts (#94 and #95).

    The video does correlate the mass extinction at the end of the Permian with the 40,000 years of intermittent continental flood basalts eruptions from volcanism in the Siberian Traps. This much is mainly fact. Then, Wignall infers that CO2 released from the basalts increased atmospheric CO2 sufficiently to cause a 4-5 degree C temperature rise and trigger the breakdown of methane hydrates——a positive feedback effect that supposedly added another 5 degrees to the temperature rise and enhanced the extinction to include an impressive 95 percent of all living species. This is not mainly fact; it is mainly interpretation. It will serve as a useful working hypothesis for future research to confirm or disprove, but it is not yet an established fact, as far as I know. Your post, however, seems to assume that the inferred CO2 release from the basalts did in fact cause a 4-5 degree C temperature rise. I don’t think that was established at the time the video was made. Perhaps you know of subsequent studies that established it.

    Here’s what I would like to know: You say, “My understanding of the Siberian Traps volcanoes leads me to believe that they were releasing far more CO2 (100,000 gigatons of carbon) than we do…” Is this 100,000 gigatons total carbon for the entire 40,000 years, or is it an average per year estimate of 100,000 Gt carbon? The video makes no mention of a 100,000-Gt carbon release from the basalts of the Siberian Traps. So, where does this number come from? Is it from a published study? If so, please give the reference. If it is your number, how did you arrive at it? How much basalt was involved and what was its weight-percent pre-degassing CO2 content?

  49. 99
    Clif Westin says:

    #94 Yup, sorry, misprint, it was Greenland. ” Wignall suspected all the explanations for the extinction had been based on insufficient data. He also knew there was one place he might find more: Greenland. It’s a country known to contain Permian rock, but always considered too difficult to explore. In the late 1990s he took a gamble and flew out there.”

    Any thoughts on his findings?

  50. 100
    Clif Westin says:

    #98 Q: Is this 100,000 gigatons total carbon for the entire 40,000 years, or is it an average per year estimate of 100,000 Gt carbon? The video makes no mention of a 100,000-Gt carbon release from the basalts of the Siberian Traps. So, where does this number come from? Is it from a published study? If so, please give the reference. If it is your number, how did you arrive at it? How much basalt was involved and what was its weight-percent pre-degassing CO2 content?”

    I went looking to find out how much was released and found a couple of sources that gave me a number. I, too, don’t know the duration, I’m asking. Here’s one place I found it (obviously not definitive, and not the original sites, you can never find them when you need them) They might reference a source in there. (in my best Dr. McCoy “I’m an engineer darn it, not a climate scientist!) The amount of basalt is stated as roughly the size of the US and about 8 miles thick (if memory serves and from other sources)…so, a lot? I would suggest reaching out to Wignall, he’s at Leeds isn’t he?