Anthropogenic CO2 Far Exceeds Volcanic

I was a little startled a few weeks back to see in a Waikato Times column written by former National Party MP Michael Cox the extraordinary claim that the 1991 Mt Pinatubo eruption “shot out more greenhouse gases into the atmosphere than the entire human race had emitted in its entire years on Earth”.  I don’t know where he derived this from – no doubt it’s floating around somewhere in the denial world, though even there it seems possible that he misunderstood what he was reading. Anyway it served to support his view that talk of human-caused warming is a Left-inspired crusade to compensate for the collapse of communism! I was able to say in a letter to the paper how ridiculous the Pinatubo statement was, and pretty much everything else he said as well.

Ian Plimer’s book Heaven and Earth claims that “Volcanoes add far more carbon dioxide to the oceans and atmosphere than humans”. Perhaps that was Cox’s source. Plimer obviously still carries weight with those looking for alternatives to climate science, as a recent Herald piece from cartoonist Peter Bromhead revealed. Bromhead’s denialism survived unscathed a flight to New York sitting next to a climate scientist. It was difficult “for a bewildered old cartoonist to try to verbally outrun somebody professionally clued up on his subject”. But he did detect that “my companion’s viewpoint appeared disturbingly contaminated with doctrine that leaned heavily on ideology rather than absolute fact.” And Bromhead had that “admirably comprehensive book” Heaven and Earth as counterweight. “This volume, with thousands of scientific references on every aspect of climate change – through the history of the planet – is a must-read for those bewildered by climate contradictions.”

All of which is a rather circuitous introduction to my purpose in this post to draw attention to a very worthwhile article on volcanic CO2 emissions. Terry Gerlach, a retired volcanic gas geochemist who worked with the US Geological Survey, has a guest commentary in Real Climate introducing his article Volcanic Versus Anthropogenic Carbon Dioxide which was published in the American Geophysical Union’s publication Eos, and is now available online. In the article he addresses the widespread misperception that volcanic CO2 emissions greatly exceed anthropogenic CO2 emissions. He presents an overview of the subject, using only published peer-reviewed data with a minimum of technical jargon and aimed at a broad readership. I’ve read it and I can confirm its accessibility for the general reader. A few points from it:

Anthropogenic CO2 emissions were estimated to be responsible for a projected 35 gigatons of CO2 in 2010. This clearly dwarfs all estimates of the annual present-day global volcanic CO2 emission rate of around 0.26 gigaton, which Gerlach points out is comparable to the global CO2 emissions from the flaring of waste gases, or to the CO2 emissions of nations such as Pakistan (0.18 gigaton), Kazakhstan (0.25 gigaton), Poland (0.31 gigaton), and South Africa (0.44 gigaton). Anthropogenic emissions were projected to be 135 times as great as volcanic emissions in 2010.

Occasional volcanic paroxysms such as Mount Pinatuboin 1991  or Mount St. Helen’s in 1980 may for a few hours equal or even exceed the human output during those same few hours, but “volcanic paroxysms are ephemeral, while anthropogenic CO2 is emitted relentlessly from ubiquitous sources.” Gerlach considers what would be needed by way of volcanic activity to exceed the CO2 levels due to human activity, and concludes “… the belief that volcanic CO2 exceeds anthropogenic CO2 implies either unbelievable volumes of magma production or unbelievable concentrations of magmatic CO2”.  It would take 700 Mt Pinatubo-equivalent volcanic paroxysms annually to match the yearly level of anthropogenic emissions.

Even supereruptions don’t compare.  He describes them as 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. “[Calculations] strongly suggest that present-day annual anthropogenic CO2 emissions may exceed the CO2 output of one or more supereruptions every year.”

The article performs a very useful function in gathering and referencing the work that scientists have done on the issue and spelling out the comparisons. In a quiet and restrained way it underlines just how massive a disruption the human release of fossil fuel CO2 is to the natural processes by which Earth’s vital carbon cycle is maintained. It’s very difficult to believe that the consequences can’t be severe. The author in conclusion stresses the need for educators, climate change policy makers, the media, and the general public to understand that anthropogenic CO2 dwarfs volcanic emissions. “Discussions about climate policy can only benefit from this recognition,” is his final sentence. He’d have been justified in using stronger language.

I should also mention a shorter and simpler article by Gerlach published by Earth Magazine last year in which he specifically addressed Plimer’s assertions on the size of volcanic emissions and took them apart.

15 thoughts on “Anthropogenic CO2 Far Exceeds Volcanic”

  1. Around a similar time I was forwarded an email that said the exact same thing, word for word, from an elderly family member. The email had all the markers to quality denialist tripe, pink HTML text, generous use of capital letters, accusation of socialist leanings, and of course the Plimer inspired zombie myth regarding C02.

    I attributed the timing of the email to the Australian C02 fight, and happily replied to all 50 other recipients to correct the fallacies within.

    I suspect Mr. Cox simply copy and pasted the email to the Waikato times.

  2. nzjrs, I received a similar chain e-mail at work around the time of the unpronouncable Icelandic volcano’s eruption, which also was managing to spew out more CO2 than all human activities combined ever (So what do you think of that Mr. Climate Science Socialist Smartypants, eh!?) at the time!

    And I similarly replied to all recipients pointing out that a mere trip to the websites of the institutions that were supposedly being cited in support of this outlandish idea (what the hell would it mean for the earth’s climate if it were true?!) was enough to absolutely disprove it.

    However, the response I got from a disturbingly large number of people was something along the lines of ‘Oh, you may have facts on your side, but I’m keeping an open mind in this matter’.

    So open, I’m afraid, that their brains have fallen out.

    It’s increasingly obvious that it’s not just Big Oil and Big Capitalism we’re up against, it’s their unholy alliance with Big Stupid, too. And not just in this matter, there’s a wave of reactionary Stupidity sweeping the western world; witness the Tea Party’s string of ‘triumphs’.

    The ‘information deficit’ model of the AGW debate – and others – is clearly wrong – people don’t believe bullshit because they don’t have access to better information, they believe it because they prefer to.

  3. Oh dear, I used the S word! (That’s S*cialist, sports fans. ‘Shit’ ain’t a problem.). Can I flag I’ve got one stuck in the moderation queue, please, Bryan?

    Sorry about being caught up in moderation Bill – the system seems to have developed a mind of its own and is arbitrarily selecting comments for moderation. I’ve been out for a while so didn’t pick it up. Bryan

    1. Thanks, Bryan; Gareth has flagged that the American made WordPress filter takes regular exception to the ‘people-who-sing-the-Internationale’ word.

      And I was apparently wrong about the other ‘s’ word, incidentally! 😉

      1. Talking about “Word Filters”: I had the opportunity to sample a few editions of “The Australian” lately…. oh dear. In comparison our NZ Herald looks like walk on the bright side. There was not one edition that did not sport at least one if not more AGW obfuscating articles standing without comment or complaint by sane voices.

        Then a tour guide on an outing to White Haven beech in the Whitsundays pointed to the whitish and dead coral skeletons passing under the glass bottom of the boat and told his captive audience of clueless tourists that “white is the healthy color of the best coral varieties” and that that keeps “growing strongly” year after year as he could attest to having done this trip for the last 25 years…. and all that talk about the reef dying was just bs…

        Oh dear….. I managed to contain myself barely as turning a nice day into a disaster for the tour guide seemed like a pointless exercise.
        Is there any authority that regulates reef tours and assures that guides have some clue about ocean ecology??? Perhaps somebody with some authority should go on a trip with the “Whiteheaven Express” and sort these cowboys out!

  4. I understood that the annual anthropogenic emissions of 32 gigatons or so was about 4% of total annual emissions. If so, the other 760Gtpa must be coming from somewhere.

    Is that all part of the carbon cycle, coming out of the biosphere and hydrosphere and roughly offset by sinks of the same magnitude?

    Where do the volcanic emissions go? Do they remain in the atmosphere or do sinks expand to absorb them?

  5. 760Gtpa! OMG where did you get that figure? Out of thin air or somewhere less pleasant? If that were the case we would be toast by now.
    Read the post above and for heavens sake and your only edification download and READ the article to which Bryan refers – it’s all there.

    1. What Australis refers to are absolute flows not net flows.

      There are large closely balanced flows between the oceans and the air and between the rest of the biosphere (plants and soils) and the air.

      What matters however are the net flows. It does not matter that some 60GT of CO2 are exchanged between the oceans and the air each year as this simply observes the fate of individual CO2 molecules which have a certain statistical chance to come out or go into the oceans while overall a balance remains to keep the partial pressures of CO2 in the air an in the water balance out.

      At the moment there is a net flow of CO2 from the air into the oceans mirroring the rise of atmospheric CO2.

      The net flows matter and here the induction of the industrial release of CO2 is the king player and well outshines any natural net flows.

  6. A point of clarification. The most recent documented supereruption is the Oruanui eruption from Taupo about 26,000 years ago. There are several others around the world that are younger than the 2 million year old Huckleberry Ridge eruption from Yellowstone as well. This does not diminish the validity of Gerlach’s conclusions.

      1. And a last frantic bid to maintain the current economic status quo. Factors – mainly of their own greedy making – may however, result in a world community waking up to the fact that the Market’s “hidden hand” is failing us yet again!

    1. Australis – “Matt Ridley draws attention to a recent paper by Prof Murray Salby’

      Yup, not only does Professor Salby from MacQuarrie University, not have a clue about the carbon cycle (you have listened to his podcast right?), but if you extrapolate his model back 4°C cooler (it was 5-6°C cooler in the last ice age) then Earth’s atmospheric carbon dioxide was a negative value, and therefore the planet was a snowball, and no photosynthetic plant life existed.

      Sound about right to you? What about Manny, Sid, Diego and Scrat?

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