Volcanoes Have Little Impact On Atmospheric CO2 – And Also A Huge Impact

The volcano/CO2 story flip-flops depending on what the agenda for the day is. Some days it is convenient to blame past climate change on volcanic CO2.

Multiple phases of carbon cycle disturbance from large igneous province formation at the Triassic-Jurassic transition
M. Ruhl and W.M. Kurschner, Palaeoecology, Laboratory of Palaeobotany and Palynology, Institute of Environmental Biology, Faculty of Science, Utrecht University, Budapestlaan 4, NL-3584 CD Utrecht, Netherlands; doi: 10.1130/G31680.1.
The end-Triassic mass extinction event (~200 million years ago) is one of the Big Five mass extinction events in earth history. It is marked by global extinction of up to 50% of all species living in the oceans and by large changes in ecosystems on the continents. The cause for the extinction event is related to strongly intensified volcanic activity and deposition of the largest basalt deposit on Earth, the Central Atlantic Magmatic Province. Recent studies show that the end-Triassic mass extinction event directly coincided with the onset of this volcanic period that lasted for ~600,000 years. The release of massive amounts of carbon dioxide from volcanism triggered a strong change in the global carbon cycle and likely had a strong impact on global climate. M. Ruhl and W.M. Kurschner of Utrecht University show, however, that a strong increase in atmospheric carbon dioxide of up to 1000 parts per million (today’s values are ~350 parts per million) and a strong change in the global carbon cycle already occurred ~100,000 years before the onset of intense volcanism. This suggests that large amounts of carbon dioxide were already released by the thermal heating of organic-rich sediments by intrusion of magma bodies from the mantle on their way to Earth’s surface.


On other days, they want to prove that volcanoes aren’t major contributors of CO2.

The burning of fossil fuels and changes in land use results in the emission into the atmosphere of approximately 30 billion tonnes of carbon dioxide per year worldwide, according to the EIA. The fossil fuels emissions numbers are about 100 times bigger than even the maximum estimated volcanic CO2 fluxes. Our understanding of volcanic discharges would have to be shown to be very mistaken before volcanic CO2 discharges could be considered anything but a bit player in contributing to the recent changes observed in the concentration of CO2 in the Earth’s atmosphere.



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11 Responses to Volcanoes Have Little Impact On Atmospheric CO2 – And Also A Huge Impact

  1. Andy Weiss says:

    Even peer review does not guarantee a consistent conclusion!

    • Latitude says:

      The whole problem with peer review, is that your peers are on the same page that you are……

      It would be more real if it were called consensus review.

      • Jimbo says:

        Well said! It could also be called pal review. You scratch my back and I’ll scratch yours. ;O)

        They have their snoughts in the money trough and aren’t goint to let go no matter what happens to global mean temps. I’m serious.

  2. Peter Ellis says:

    Because an individual volcano erupting during a given year is exactly the same as the onset of the largest ever volcanic period, that ultimately lasted 600,000 years. No difference in magnitude at all.

    • Sorry Charlie. Sane geologists don’t buy the idea that Earth processes were fundamentally different in the past.

      • Peter Ellis says:

        Same process, different magnitude.

        Day-to-day volcanism = raindrops
        Fossil fuel emissions = fire hose
        end-Triassic volcanic period = tsunami

        It’s all water, but the damage caused is affected by the amount released. Same goes for CO2.

        • You don’t really believe that crap do you? The same earth process are happening all the time. The rate of heat flow from the mantle is nearly constant. There is no rational reason to believe in a huge surge in volcanism.

      • Paul H says:

        No Steve, he does not really believe that crap.

  3. Edward says:

    As we have only ‘fairly accurate’ measurements for CO2 since 1958, er a lot of this [above links] stuff is highly speculative guff.
    Volcanic activity on this planet’s surface/crust [imho] is greatly underestimated… undersea vents, tectonic spreading plate ridges, island arcs – on land – volcanoes, calderas, geysers and ‘hot spots’ all over the world lead one to surmise, that as yet on volcanicity, we do not know and what we are talking about can only be appraised as speculative, not quantitive.

    The earth is a highly active planet, the massive forces below, in the crust and upper mantle, are not fully understood, we’re barely scratching the surface– as it were.

  4. Colin Henderson says:

    The “good” CO2 released by volcanoes is used by plants to store energy, mitigate global warming, and produce oxygen while “bad” CO2 produced by burning fossil fuels is responsible for climate change. DUH

  5. Micha Ruhl says:

    Peter Ellis is right in saying that it is all about the magnitude.
    The volcanic eruptions at the Triassic-Jurassic transition caused the deposition of an enormous amount of basalts, spread over four continents. The volume of basalt deposits from these eruptions would cover the continental United States with a 200m thick pile of rock. That is not exactly what we see happening from volcanic activity today. So yes, the amount of volcanic activity changed dramatically through earth’s history!
    It is therefore fair to say that the smaller amount of CO2 released from volcanic activity today may have less impact on earths climate than the CO2 released from volcanic activity in earth’s past.
    Anyhow, with geochemical and mathematical methods scientists can calculate how much CO2 was released in a certain period in earth’s history. The amount of CO2 released during the Triassic-Jurassic transition is similar as what humanity will release uptill the year 2100. The Triassic-Jurassic volcanic period also exactly coincides with one of the largest extinction events in earth history. Something to think about..

    Ps the peer review system is anonymous. It works in a way that scientists, who do not know the author of a paper and in no way are connencted to the author, judge the scientific quality of that paper. If it is not good enough (regardless of personel opinion, just scientific quality), than a paper is rejected for publication. So no scratching backs, making money, helping friends etc…

    regards Micha

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