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Do volcanoes emit more CO2 than humans?

What the science says...

Select a level... Basic Intermediate

Humans emit 100 times more CO2 than volcanoes.

Climate Myth...

Volcanoes emit more CO2 than humans

"Human additions of CO2 to the atmosphere must be taken into perspective.

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." (Ian Plimer)

The solid Earth contains a huge quantity of carbon, far more than is present in the atmosphere or oceans.  Some of this carbon is slowly released from the rocks in the form of carbon dioxide, through vents at volcanoes and hot springs. Volcanic emissions are a small but important part of the global carbon cycle. Published reviews of the scientific literature by Mörner & Etiope (2002) and Kerrick (2001) report a range of emission of 65 to 319 million tonnes of CO2 per year. Counter claims that volcanoes, especially submarine volcanoes, produce vastly greater amounts of CO2 than these estimates are not supported by any papers published by the scientists who study the subject. 

The burning of fossil fuels and changes in land use results in the emission into the atmosphere of approximately 34 billion tonnes of carbon dioxide per year worldwide, according to the U.S. Energy Information Administration (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.

Volcanoes can—and do—influence the global climate over time periods of a few years but this is achieved through the injection of sulfate aerosols into the high reaches of the atmosphere during the very large volcanic eruptions that occur sporadically each century. But that's another story...

Recommended further reading on CO2 and volcanoes can be found here: Terry Gerlach in Earth Magazine ; USGS

Last updated on 2 June 2017 by John Cook. View Archives

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Further reading

Tamino has posted two examinations of the "volcanoes emit more CO2 than humans" argument by looking at the impact of the 1991 Pinutabo eruption on CO2 levels and the impact of past super volcanoes on the CO2 record.

The Global Volcanism Program have a list of all volcanoes with a Volcanic Explosivity Index (VEI) greater than 4 over the past 10,000 years.

Myth Deconstruction

Related resource: Myth Deconstruction as animated GIF

MD Volcano

Please check the related blog post for background information about this graphics resource.


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Comments 226 to 250 out of 308:

  1. Note "Study: Volcanoes Unleash El Niño" is about the symptoms, not the cause.
  2. ps Dr. S.D. Meyers and Dr. J.J. O'Brien. "Variations in Mauna Loa carbon dioxide induced by ENSO" Which I wanted to link for you has been surpressed by the new regime but is worth reading if you can find a bootleg copy.
  3. Sometimes, and for reasons not fully understood, the trade winds do not replenish, or even reverse direction to blow from west to east. When this happens, the ocean responds in a several ways. Warm surface waters from the large, warm pool east of Indonesia begin to move eastward. Moreover, the natural spring warming in the central Pacific is allowed to continue and also spread eastward through the summer and fall. Beneath the surface, the thermocline along the equator flattens as the warm waters at the surface effectively act as a 300-foot-deep cap preventing the colder, deeper waters from upwelling. As a result, the large central and eastern Pacific regions warm up (over a period of about 6 months) into an El Niño. On average, these waters warm by 3° to 5°F, but in some places the waters can peak at more than 10°F higher than normal (up from temperatures in the low 70s Fahrenheit, to the high 80s). In the east, as temperatures increase, the water expands, causing sea levels to rise anywhere from inches to as much as a foot. But in the western Pacific, sea level drops as much of the warm surface water flows eastward. During the 1982-83 El Niño, this drop in sea level exposed and destroyed upper layers of coral reefs surrounding many western Pacific islands. Yeah, I know that you really did want to know that either.
  4. The real cause of El Ninos is still obscure. However, the recent discovery of over 1,000 previously unmapped submarine volcanos rising from the seafloor in the eastern Pacific may lead to El Nino's source. The synchronous eruption of, say, 100 of these volcanos might warm the ocean around Easter Island a tad---just enough to warm the atmosphere above a bit---resulting in a shift of the high pressure area. The area of intense volcanic activity covers 55,000 square miles of sea floor where the Pacific and Nazca plates are separating. In addition to the active volcanos, many plumes of 800°F water gush from the sea floor in this area. The volcano-El Nino link is, therefore, not so far-fetched. (Nash, Nathaniel C.; "Volcano Group in Pacific May Cause El Nino," Pittsburgh Post_Gazette, February 14, 1993. Cr. E. Fegert) Comment. If submarine volcanos do cause the El Ninos, and the El Ninos are periodic, the submarine volcanism would have to be periodic, too. This implies an unrecognized rhythm in the earth's internal fires. -
  5. Here is a different view: As far as deep-ocean vents modifying the ocean temperatures, researchers now think that this source of heat does contribute to the long-term evolution of the ocean state. We can trace the chemical signatures of sea floor venting carried for quite a distance in the deep currents. Those traces are useful for estimating the deep flows, which are difficult and expensive to measure directly since they are so slow. However, we observe that the heating due to deep venting becomes diluted in the vast reaches of the abyssal ocean and therefore does not make quick changes in the ocean state. These affects are felt over decades or centuries, not on the relatively rapid time scale of El Niño. It is indeed tempting to look for simple causes of complex oscillations like the El Niño cycle. Unfortunately (or perhaps fortunately for those of us who like scientific challenges), it seems that the ocean-atmosphere system is well capable of generating these oscillations on its own, and the task now is to understand how this happens. Volcanoes and sea floor venting are part of the slowly changing background state to which phenomena like El Niño are added, and they increase the complexity of the task. Sorry, I still can't where the hypothesis is spelled out.
  6. I give up. When I first looked to find the cause there was one page of search results now there are hundreds.
  7. This is cut and paste from the original article that I can't locate: Although scientists understand the mechanics of El Nino, its origins have yet to be determined. The new theory [of the cause of El Nino] suggests that the primary mover behind El Nino is hot magma welling up between tectonic plates on the Pacific sea-floor. The upwelling magma heats the overlying waters enough to affect the ocean surface, initiating the cascade of events that brings on the wrath of El Nino. This, while not the same source says the same thing: Hot Vents and Global Climate Every two to seven years a climatic disturbance brings floods to California, droughts to Australia, and famine to Africa . Known as El Nino, it is essentially a warming of surface waters in the eastern Pacific near the equator. Although scientists understand the mechanics of El Nino, its origins have yet to be determined. Most believe that the interaction between the atmosphere and the sea somehow generates this climatic disturbance that wreaks havoc upon those regions of the world that lie in its path. But now a new theory on the origins of El Nino has been proposed and, surprisingly, it has very little to do with the atmosphere or the sea. The new theory suggests that the primary mover behind El Nino is hot magma welling up between tectonic plates on the Pacific sea-floor. The upwelling magma heats the overlying waters enough to affect the ocean surface, initiating the cascade of events that brings on the wrath of El Nino.
  8. Now that this has all been explained, what I need to now point out is that this is now a cause of GW, in fact has nothing to do with long range climate change (that is the Sun and little to do with the recent "AGW" issue). This is a side show, and the reason for melting of poles and some glaciers in specifically over the subduction zones IMO. This side show is also attributable to the Solar Jerk as a side effect on the Earth itself IMO. Bottom line, it's all comes back to the Sun as the driver of climate via both direct and indirect means. Ok, I think I made my point, now it's up to you to try to understand what I explained. Denial of the Sun and the results of the Solar Jerk in IMO is a silly argument so I am done. I have more paleontologist issues pressing to get back to.
  9. Regarding the leaking of heat from the Earth's interior, from volcanoes, rifts, and everything else, both above and below water, here are some sources of info: A summary is in section 17.4.1, Global heat flow, of Mussett & Khan's Looking into the Earth: An Introduction to Geological Geophysics (2000, Alan E. Mussett & M. Aftab Khan, page 279, free online partial preview). 71% of the Earth interior's heat loss is from ocean-covered surface; you can see a breakdown in section 7.4, Worldwide heat flow: total heat loss from Earth, especially Table 7.3 on page 286, of Fowler's The Solid Earth: An Introduction to Global Geophysics (2nd Edition, 2005, C.M.R. Fowler, free online partial preview). An even more detailed breakdown, even across types of undersea crust, is in Pollack, Hurter, & Johnson (1993, Heat Flow from the Earth's Interior: Analysis of the Global Data Set, Reviews of Geophysics, Vol. 31(3), pages 267-280, full text available for free). A more recent source that is just as technical as the 1993 Pollack, Hurter, and Johnson article is the 2005 book chapter by Jaupart and Mareschal, Constraints on Crustal Heat Production from Heat Flow Data (in R.L. Rudnick (Ed.), The Crust, pages 65-84, free online partial preview). A summary of how the experts calculate the heat flow from the crust that is covered by oceans are in that same Fowler book, section 7.5, Oceanic Heat Flow, starting on page 288 (free online partial preview). Details are in that same 1993 Pollack, Hurter, & Johnson article (full text available for free) and that same 2005 book chapter by Jaupart and Mareschal (free online partial preview). Those experts say that the total heat from the Earth's interior arriving at the Earth's surface (covered by land plus covered by sea) is about 0.09 watts coming out of each square meter from the Earth's interior. That's about 10,000 time less than the energy from the Sun (1,370 watts/m^2 on the sunlit side). That is such an inconsequential amount that any changes in it since 1850 cannot possibly have any significant effects on global temperature, compared to the other forcings such greenhouse gases and even solar variability. Furthermore, the observations of heat loss from the Earth's interior have not revealed any significant changes in the time frame of anthropocentric global warming. So heat emission from the Earth's interior simply is not a significant player in the era of anthropocentric global warming.
  10. Regarding my comment 236: Of course I meant "anthropogenic," not "anthropocentric." John Cook quite rightly pointed out to me that the best comparison of the total amount of heat leaking from the Earth's interior (0.09 watts/m^2) is comparison against known forcings rather than against any total. For example, it's better to compare against forcing from variations in the Sun's radiance rather than against the total of the Sun's radiance. Or against the forcing from CO2, which is 2.66 watts/m^2. Comparison to forcings show that any forcings from variations in the amount of heat from the Earth's interior will be tiny in comparison to the known forcings from variations in other factors such as CO2 or solar radiance. Suppose that the heat from the interior had doubled without us noticing (a ridiculous supposition). That would mean the heat from the interior would have increased by only 0.18 w/m^2--a tiny fraction of the current CO2 forcing of 2.66 watts/m^2.
  11. In my comment 237 I wrote the heat from the interior would have increased by only 0.18w/m^2. Wrong. The increase would be only 0.09--even smaller compared to the forcing from CO2.
  12. FYI the Icelandic volcano under the Eyjafjallajokull glacier, although still erupting has been clasified as quite low on the Volcanic Explosivity Index compared to Mt Pinatubo which rated a 6 on the 1 to 8 scale.
  13. It is useful to compare the volcano in iceland and its 150-300 ktons per day to the EU cuts. According to this article, the EU cut about 174 ktons per day in 2008. The Icelandic volcano emits about 150-300 ktons per day, a comparable amount. Of course the volcano will stop emitting at some point, but for now it is a valid skeptical talking point to say that the volcano undoes the EU cuts.
  14. Eric (skeptic), we should be grateful that the EU has made such cuts, otherwise the increase in CO2 would be even greater now with the volcanoes added input. Just think how worse things would be if the EU hadn't made those cuts - especially if the volcano were to continuing erupting such amounts for a full year, which is unlikely.
  15. JMurphy, I posted a response earlier, but it may have been deleted or I might have screwed up. I didn't say much more than I disagree mainly because the EU cuts (and naturally the volcano) are inconsequential for climate. But that argument probably belongs on a different thread.
  16. Sorry to ask such a basic question, but the threads get too complicated for me. The rebuttal argument was very concise for this topic and I'm curious if there is any dispute. I took a quick look aound and didn't find one. Regardless of the other effects of volcanoes, or what happens to the gasses, does anyone dispute the numbers stated in the response that: 1. Volcanoes emit around 0.3 billion tonnes of CO2 per year. 2. Human CO2 emissions are around 29 billion tonnes per year. ? Thanks
  17. JSFarmer, apart of Ian Plimer, (professor of mining geology and director of a few mining companies in Australia) and Mark Durkin (director of the infamous "The Great Global Warming Swindle") I don't think you can find many others disagreeing with your question #1. As for question #2, i've never heard criticism on the numbers.
  18. OK.... Thanks...
  19. Do Volcanoes produce more CO² each year than man? Clearly no normally, but that is not to say they cannot. However we must not forget that Volcanoes emit more than just CO². Whilst I do not agree with AGW, I personally think that under normal circumstances Volcanoes are a Red herring. If you take into account the dust and other contaminants they inject into the air, then I would hazard a guess (and this is born out by human experience and scientific data), that Volcanoes have more of a cooling effect than a warming one. As with most things in science, it is not impossible for our rudimentary understanding of tectonic processes to proves us wrong with the odd eruption, but as a rule, we would need some very serious eruptive events to account for 30 Billion Tonnes of CO², assuming this figure too is correct.
  20. New article adds the contribution from volcanic lakes Including this contribution, total volcanic CO2 emissions could be as high as 420Mt/y, or closer to 2% of human emissions if we use the 23Gt figure from the Skeptic's guide. Still negligable, but worth noting.
  21. A recent update from AGU:
  22. The link to "Morner 2002" is broken. Can I get a good one? Sadly, I need it.
  23. It occurs to me,


    Why not have a "Counter" set at

    human greenhouse gas emissions are equaling x volcanes erupting,

    (say... X Mt. Pinnatubos = current human emissions?)

  24. Your Moerner and Etiope and Kerrick links are dead.


    [DB] Mörner and Etiope is here.  Kerrick is here.  A nice chapter on geologic methane by Etiope is here.

  25. There is a more recent paper on the topic:

    Burton, Michael R., Georgina M. Sawyer, and Domenico Granieri. "Deep carbon emissions from volcanoes." Rev Mineral Geochem 75 (2013): 323-354.

    This estimates that the total volcanic emission is 637 million tonnes per year.

    Most existing volcanoes have not been measured, so all estimates have large uncertainties.


    [PS] Added link to paper

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