Surprise: Volcanos cause more CO2 emission than previously thought

Posted: November 29, 2016 by tallbloke in atmosphere, Carbon cycle, solar system dynamics, Uncertainty, volcanos

cardellini_scrTalkshop readers with good memories may remember the article I wrote back in 2012 on findings by Cardellini et al that volcanic soils emitted far more CO2 than previously thought (and are not included in IPCC carbon cycle inventories). The implication is that longer sunshine hours during the 1980s-90s may well have released a lot of sequestered CO2 from these soils, thus raising atmospheric levels. Which would mean humans are not responsible for all of the increase, as has long been assumed.

Now another article from Robert Wylie on raises the issue again:

Robin Wylie, is a doctoral candidate in volcanology, atUniversity College London. He contributed this article to LiveScience’s Expert Voices: Op-Ed & Insights.

The exploding hills really give the game away: We’ve always known the Earth is a smoker. The true extent of its habit, though, is only just beginning to surface.

Before the human species found its talent for pyromania, atmospheric levels of the Earth’s greenhouse superstar, carbon dioxide (CO2), were controlled, for the most part, by volcanoes.

Since our planet emerged from the debris which formed the solarsystem, some four and a half billion years ago, a lifetime supply of primordial carbon has been locked away in the mantle — against its will. Partnering with oxygen and smuggled as a dissolved gas in liquid rock, it breaches the surface at our planet’s volcanic airways: CO2, then, has been seeping into the planet’s atmosphere for as long as there has been one.

Until the end of the 20th century, the academic consensus was that this volcanic output was tiny — a fiery speck against the colossal anthropogenic footprint. Recently, though, volcanologists have begun to reveal a hidden side to our leaking planet.

Exactly how much CO2 passes through the magmatic vents in our crust might be one of the most important questions that Earth science can answer. Volcanoes may have been overtaken in the carbon stakes, but in order to properly assess the consequences of human pollution, we need the reference point of the natural background. And we’re getting there; the last twenty years have seen huge steps in our understanding of how, and how much CO2 leaves the deep Earth. But at the same time, a disturbing pattern has been emerging.

In 1992, it was thought that volcanic degassing released something like 100 million tons of CO2 each year. Around the turn of the millennium, this figure was getting closer to 200. The most recent estimate, released this February, comes from a team led by Mike Burton, of the Italian National Institute of Geophysics and Volcanology – and it’s just shy of 600 million tons. It caps a staggering trend: A six-fold increase in just two decades.

These inflating figures, I hasten to add, don’t mean that our planet is suddenly venting more CO2.

Humanity certainly is; but any changes to the volcanic background levelwould occur over generations, not years. The rise we’re seeing now, therefore, must have been there all along: As scientific progress is widening our perspective, the daunting outline of how little we really know about volcanoes is beginning to loom large.

Quiet monsters

The exhalations of our planet can be spectacularly obvious. The fireworks, though, are only part of the picture. We now know that the CO2 released during volcanic eruptions is almost insignificant compared with what happens after the camera crews get bored. The emissions that really matter are concealed. The silent, silvery plumes which are currently winding their way skyward above the 150 or so active volcanoes on our planet also carry with them the bulk of its carbon dioxide. Their coughing fits might catch the eye — but in between tantrums, the steady breathing of volcanoes quietly sheds upwards of a quarter of a billion tons of CO2every year.

We think. Scientists’ best estimates, however, are based on an assumption. It might surprise you to learn that, well into the new century, of the 150 smokers I mentioned, almost 80 percent are still as mysterious, in terms of the quantity of CO2 they emit, as they were a generation ago: We’ve only actually measured 33.

If the 117 unsampled peaks follow a similar trend, then the research community’s current projection might stand. But looking through such a small window, there’s no way of knowing if what we have seen until now is typical or not. It’s like shining a light on a darkened globe: randomly, you might hit Australia, and think you’d seen it all – while on the edge of your beam, unnoticed, would be Asia. Our planet’s isolated volcanic frontiers could easily be hiding a monster or two; and with a bit of exploration, our estimate of volcanic CO2 output could rise even higher.

You’d think that would be enough. That might be my fault — I tend to save the weird stuff until the end. Recently, an enigmatic source of volcanic carbon has come to light that isn’t involved with lava — or even craters. It now seems that not only is there CO2 we can’t get to, there’s some we can’t even see.

Carbon dioxide is always invisible, but its presence can be inferred in volcanic plumes — betrayed by the billowing clouds of water vapour released alongside it. Without the water, though, it’s a different story. The new poster-child of planetary degassing is diffuse CO2 — invisible emanations which can occur across vast areas surrounding the main vents of a volcano, rising through the bulk of the mountains. This transparent haze is only just beginning to receive proper attention, and as such we have very little idea of how much it might contribute to the global output.

Even more incredibly, it even seems that some volcanoes which are considered inactive, in terms of their potential to ooze new land, can still make some serious additions to the atmosphere through diffuse CO2release. Residual magma beneath dormant craters, though it might never reach the surface, can still ‘erupt’ gases from a distance. Amazingly, from what little scientists have measured, it looks like this process might give off as much as half the CO2 put out by fully active volcanoes.

If these additional ‘carbon-active’ volcanoes are included, the number of degassing peaks skyrockets to more than 500. Of which we’ve measured a grand total of nine percent. You can probably fill it in by now — we need to climb more mountains.

  1. fearocean says:

    Plants breath CO2 , in fact there are Co2 Generators for indoors

  2. […] a través de Surprise: Volcanos cause more CO2 emission than previously thought — Tallbloke’s Talkshop […]

  3. […] via Surprise: Volcanos cause more CO2 emission than previously thought — Tallbloke’s Talkshop […]

  4. pochas94 says:

    But what if CO2 has no harmful effects and the IPCC is only an echo chamber for zealots. Think of the time we have wasted worrying about nothing!

  5. Saurab says:

    I wouldn’t say it is a waste. Maybe global warming will not be something for us to worry about, but climate change is something different.
    Even if this seems like a natural variation, there is no surity that humans will be able to adapt.
    Also, there is the other issue of environmental degradation and the associated loss of biodiversity. While IPCC does not directly deal with these issues, they are still in the limelight because of the climate change talks. Governments, in their quest to curb the effects of climate change are focusing a lot on preventing environmental degradation. I’d say that is time very well spent.

  6. Saurab says:

    That’s a very well written post!
    This research is certainly very enlightening. I had never studied in class about gas emissions without an eruption occurring. If this estimate is even close to the truth, it would debunk much of the global warming hypothesis (I say hypothesis, because I am still unconvinced by it).
    How much would the proportional figures of CO2 emissions change if we were to take these estimates into consideration?

  7. jim says:

    Remember, it’s not the co2 but the taxing of people’s to stop the co2. Now how much more to stop a volcano?

  8. is it 10% more or 100% more or 1000% more?

  9. A. Ames says:


    You said “Before the human species found its talent for pyromania, atmospheric levels of the Earth’s greenhouse superstar, carbon dioxide (CO2), were controlled, for the most part, by volcanoes.”

    This raises some interesting points, as follow.

    My understanding is that Earth began much like Venus with a hot mostly pure CO2 atmosphere. At some point plants began to grow converting CO2 to oxygen and hydrocarbons in various ways.

    Apparently the early atmosphere was net reducing and as a result many metals were dissolved in sea water. As the oxygen levels grew the oceans turned oxidizing as evidenced by the layers of iron oxides that precipitated out of the oceans. says “—this was a periodic process resulting in the alternating bands of iron oxide and shale. Oxidized iron is not soluble in water and thus it would precipitate out of the oceans and onto the muddy sea floor.”

    From any of

    CO2 persisted at several thousand ppm until a few hundred million years ago, after which alternating cycles of plant growth > CO2 loss/ repopulation by volcanos or funguses & animals/ ice ages prevailed.

    So it might well be that volcanos are secondary sources of early geologic CO2
    since precipitated and subducted into volcanic areas.

  10. Saighdear says:

    Hmm, Yes, was watching some rubbishy stuff on RT today – Jo Corre & a woman( mother? ) blethering about climate change that the Sea was responsible releasing for 80% OXYGEN + CO2….( Choke splutter) – BUT has anyone considered the O2 consumption by MARINE LIFE + the CO2 production by Same ? – this NEVER eva seems to crop up
    [mod: I think the answer is yes but as you notice it’s hard to find ]

  11. jorgekafkazar says:

    The amount of CO2 sequestered in Lake Nyos indicates CO2 from volcanic sources may be several orders of magnitude greater than thought. I calculate 8 Gigatons/yr as Carbon, assuming 3 million Nyos-similar volcanic vents, world-wide. We’ve been had.

  12. oldbrew says:

    ‘The new poster-child of planetary degassing is diffuse CO2’

    This was written in 2013 but whose ‘poster-child’ is it? We don’t seem to have heard much about it since then.

    Probably not a hot topic in climate alarm circles as it’s not ‘man-made’.

  13. tchannon says:

    If we assume, roughly speaking, that all of earth’s crust is eventually subducted then all the lime and chalk and bones will pass into the magma zone where recycling takes place, the whole earth is recycled, all circular.

  14. dennisambler says:

    There is a very interesting discussion here, going back to 2007:

    “The estimation of worldwide volcanic CO2 emission is undermined by a severe shortage of data. To make matters worse, the reported output of any individual volcano is itself an estimate based on limited rather than complete measurement. One may reasonably assume that in each case, such estimates are based on a representative and statistically significant quantity of empirical measurements. Then we read statements, such as this one courtesy of the USGS (2010):

    Scientists have calculated that volcanoes emit between about 130-230 million tonnes (145-255 million tons) of CO2 into the atmosphere every year (Gerlach, 1991). This estimate includes both subaerial and submarine volcanoes, about in equal amounts.

    In point of fact, the total worldwide estimate of roughly 55 MtCpa is by one researcher, rather than “scientists” in general. More importantly, this estimate by Gerlach (1991) is based on emission measurements taken from only seven subaerial volcanoes and three hydrothermal vent sites. Yet the USGS glibly claims that Gerlach’s estimate includes both subaerial and submarine volcanoes in roughly equal amounts. Given the more than 3 million volcanoes worldwide indicated by the work of Hillier & Watts (2007), one might be prone to wonder about the statistical significance of Gerlach’s seven subaerial volcanoes and three hydrothermal vent sites. If the statement of the USGS concerning volcanic CO2 is any indication of the reliability of expert consensus, it would seem that verifiable facts are eminently more trustworthy than professional opinion.”

  15. tallbloke says:

    DennisA: Yes, geologist Tim Casey was my source for much of the previous article I linked at the top of the post. The carbon budget is guesswork.