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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. 101
    Clif Westin says:

    Form my post #79 Sorry for my misprint, I apologize to all who went on a wild goose chase.

  2. 102

    I found this review paper from 2009; it cites the Svensmark, together with other work. They are talking about annual emissions from the volcanoes of around .03 GT/yr, as compared with current emissions of about 7 GT/yr.

  3. 103
    Ken Fabos says:

    Is it only me or do other people find it deeply disturbing that this debate is still stuck in a mire of misinformation? Two and three decades on and still on this same roundabout of refuting blatant lies and misinformation.

  4. 104
    Michael Rynn says:

    The volcano source of current CO2 has always been nonsense, as badly proposed by anti-climate change goons of geology. If average volcano activity is a major contributor to the rapid rise of CO2 in the last century, then the onus is on them to explain why all life on earth has not already been smothered in a green-house effect, during earlier increased volcanic activity periods. If volanos actually did contribute more signficantly, but not quite enough to smother all life on earth, then additional human contributions are even more deadly. Since we are all here, a mechanism to remove atmosphere CO2 faster might also be required to balance extra volcano output. Extra volcanic output would also mean an increased need to restrict human industrial output even more than previously thought. Its just as well that volcano contribution is tiny compared to human activities.

  5. 105
    Jan Rooth says:

    Clif Westin #100: Your link says “In all, the volcano may have belched as much as 100,000 gigatons of carbon into the air …” so that’s either 2.5GT/year if we use the 40,000 year number, or 0.5GT per year if we use the 200,000 year number in the article. In either case, substantially less annually than our 8GT/year infusion.

  6. 106
    Jan Rooth says:

    And note … the source of that carbon was not the volcano itself, but fossil carbon burned in the lava flows.

  7. 107
    Clif Westin says:

    Jan Rooth #105: Yup, could very well be. I was asking for some milestones in there too. All in all, there’s an event that could have lead to a massive global warming event that killed off most life on the plant. So there’s something to look at and potentially model if all the variable can be determined. That timeline is key I would suspect. Probably be best to get a hold of Dr. Wignall, he’s at Leeds. I assume he has more work and data then was presented in the documentary, I’d like to know more about this event, because that outcome, which has happened once, can tell us a lot about what’s about to happen and, specifically, when if we can get enough level of detail.

  8. 108
    Hank Roberts says:

    For Clif Westin:

    Start here:
    Put in some likely search terms from your sources you’ve mentioned above.
    You’ll find quite a few models have some relevance to your question.
    Note you can limit the start year of the period searched, which lets you leave out older papers that may be less useful.

  9. 109


    It’s not just you. This is deeply dispiriting–but like I keep saying, despair is not adaptive.

  10. 110

    #104–ah, but that’s their point: since, obviously, life wasn’t smothered by all that (mythical) CO2, that must mean that the physics that says that’s what should have happened ‘must’ be wrong.

    ‘Course, since it’s all counter-factual in the first place. . .

  11. 111
    prokaryotes says:

    “ that was published in the journal Nature in 1997 that looked at the connection between the change in the rate of sea level rise and volcanic activity in the Mediterranean for the past 80,000 years and found that when sea level rose quickly, more volcanic eruptions occurred, increasing by a whopping 300 percent.”

  12. 112
    wili says:

    When is it predicted that oceans will stop absorbing CO2? How hot will it have to get? Or will increased atmospheric concentrations always drive CO2 into rather than out of the water?

    Could future volcanic eruptions play a role in these dynamics?

    (reCaptcha sadyocc John)

  13. 113
    prokaryotes says:

    Re wili, i wonder too, and found this recent item…

    Climate change reducing ocean’s carbon dioxide uptake

    In a new analysis published online July 10 in Nature Geoscience, McKinley and her colleagues identify a likely source of many of those inconsistencies and provide some of the first observational evidence that climate change is negatively impacting the ocean carbon sink.

    “The ocean is taking up less carbon because of the warming caused by the carbon in the atmosphere,” says McKinley, an assistant professor of atmospheric and oceanic sciences and a member of the Center for Climatic Research in the Nelson Institute for Environmental Studies.

  14. 114
    wili says:

    Thank, pro. There seem to be (at least) two factors here:
    the increase in temperature reducing the amount of CO2 the water can absorb, and
    the increase in concentration of CO2 in the water (at whatever temp)

    What I am wondering now is whether there is a saturation point at which water will absorb no more CO2 no matter how high the CO2 concentration is in the atmosphere above it (and at whatever temperature you want to choose).

    And how much can we depend on overturn to take some of this CO2 saturated water down into the depths?

  15. 115
    Hank Roberts says:

    > wondering if there is a saturation point ….

    Not soon enough to matter to us at the rate we’re changing it.
    Each previous great extinction has reached some stopping point eventually.

    Perhaps you’ve heard this phrase?
    “Death is nature’s way of telling you to slow down.”