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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 51 to 75 out of 308:

  1. Another way of putting 'it': That the 155 W/m2 LW 'forcing accounts for 33 K temperature difference is itself theoretical (not so much uncertain, but it is theoretical), and couldn't be observation evidence against a 0.3 K/(W/m2) no-feedback (or feedback included in 'forcing') sensitivity.
  2. "But the greatest heat transfer occurs in regular cycles at subduction zones and that is the interesting part. What besides tidal forces can cause these cyclic events?" But I've never seen anywhere any evidence or theorty to back up the first sentence there. The closest I've come to it was a website which seemed to be stating ENSO was caused by submarine geothermal activity, but it seemed to be (ill-informed) speculation - just guessing, really (and so I didn't bother to mention it until just now).
  3. CORRECTION: PARAGRAPH IN "Patrick 027 at 14:27 PM on 24 September, 2008": "Dissipation: heat - atoms have to move around in a phase transition; conceivably, even in a short period, some portion of the atoms near phase transitions in the mantle might be cycled through different arrangements (statistically - I wouldn't imagine the phase transition is knife-edge, or that on that timescale it could get near equilibrium (?), and there are the gradual phase transitions from or to garnet, so I wouldn't expect it's the same atoms each time around) - that might be a location where there is some relative concentration of tidal dissipation into heat energy. Not that it would be a significant source of heat. I would try comparing it to the radioactive heat generation in the mantle per unit volume if I had the time. " Some of the logic I used above should be correct, BUT not the part about phase transitions dissipating the forcing that drives them into heat - that was totally wrong. Atoms move around due to thermal energy - those that have enough energy (statistically some fraction will, depending on temperature) can reach some threshold and leave the energy well of their former position in the crystal lattice (or in other situations: overcome the kinetic barrier to chemical reaction or nuclear fusion, etc.) and then fall into another position - in this case, kinetic energy is converted into potential energy, and then back into kinetic energy. Lack of thermal energy simply reduces the number of atoms that are able to move around like that, and so reduces the speed at which a phase transition can occur. Of course, if the final energy well is shallower or deeper than the initial, then there will have been a net exchange between kinetic and potential energy, which tranlates to taking up or giving off latent heat. Since material properties are temperature and pressure dependent (which is of course why the thermodynamic stability of a phase is dependent on these things), there could be a net latent heating or cooling over a cycle if the phase transition in one direction and in the reverse are not occuring at the same T,p - which of course will happen if there is a time lag due to the kinetic barrier. However, the specific heat of the material will also vary, and I suspect the end result of all this is no net temperature change over time. Except in the case that there is a net change in the microstructure over the course of many cycles - crystal grains have to form and reform, and if the grain sizes over time shrink, then there will be an increasing number of atoms whose energy is not as it would be within the crystal lattice... (PS this might build up to a point of dynamic equilibrium, beyond which factors that tend to increase grain size over time (annealing?) would balance those tending to reduce grain size over time. But anyway, as interesting as it is to consider tidal cycling of phase transitions in the mantle, I expect this is a very, very, very minor effect in the scheme of things.
  4. "However, the specific heat of the material will also vary, and I suspect the end result of all this is no net temperature change over time." Well, now I'm not sure about that...
  5. ... I was thinking of the heat content of the material at a given temperature, and the the difference in heat capacity of two phases must be related to the latent heat of phase transformation - and it's dependence on temperature, by the requirement that whatever path is taken, taking one phase at T1,p1 and ending up at another phase at T2,p2, the same net change in heat content of the material must have occured. But that's an assigned temperature change. A cycle of out-of-equlibrium (time-delayed) phase transitions might concievably require a net mechanical energy input and so would produce heat... But see the last part of comment 53 (PS I had meant to identify that it was comment 46 which contained the paragraph I was correcting in comment 53).
  6. Because I mentioned the motion of charged particles in the Earth's magnetosphere ealier: (PS all the following (except stated formula) is just from visualization; so some uncertainty in some places) About motion (velocity v) of charged particles in magnetic field B, without other forces considered (if I'm not mistaken), where component of v parallel to B is vB, the component perpendicular to B is vp, all acceleration is is in direction of vector cross-product q(v x B) = q(vp x B), which is perpendicular to v, so that |v| is constant (q is electric charge (more generally, force F = q(E + v x B), where E is electric field (as a vector), and so acceleration is proportional to q/m, m being the mass); with E set to zero, let r be the radis of curvature of the trajectory projected onto the plane normal to B; so that |vp|^2/r = centrifugal acceleration = q/m * |vp x B| = q/m * |vp||B| r = (m/q) * |vp|^2 / (|vp||B|) r = (m/q) * |vp|/|B| 1. Constant field B: helix on a cylindrical surface (field lines parallel to surface), would would appear as a straight line on the surface if unrolled. |vB| and |vp| are constant. Radius of cylinder proportional to |vp|. 2. Change in magnitude of B in direction perpendicular to B (aside from 1., the easiest to visualize): The trajectory, or it's projection onto a plane normal to B, has tighter curvature in regions of higher B. This leads to a net displacement over the course of one revolution (to where v has the same direction). Their is thus a net drift in the direction that v has in the weaker B side of the field. Looking with B vectors directed toward you, positive charges revolve clockwise (turn to the right), and the net drift is directed with the stronger B field to the right. Negative charges: opposite. Smaller q/m ratio (as with proton compared to electron): larger radius of curvature, which itself means greater net displacement over each revolution, but also means greater variation in |B| over the range of each revolution, which means even greater net displacement over each revolution. 3. Variation in field strength along B - convergence or divergence of field lines (also means, over distance perpendicular to B, change in direction of B in the same dimension): helix on a conical surface (or something like that) - vB shrinks to zero and then reverses as larger B is approached, so the trajectory is 'repelled' by larger B values. This means |vp| must rise approaching larger B. In the other direction, as B shrinks, vp also approaches shrinks as v becomes more parallel to B. 4. Over distance perpendicular to B, change in direction of B, but in direction perpendicular to both B and to the direction along which the variation is detected: Suppose there is one field line, aligned with the z-axis, where x and y = 0, about which the particle is revolving in the same dimension. Case A: variation only in the x direction, all field lines parallel to y-z planes, where in the positive x axis, field lines have increasing slope dy/dz. In this case, when v is in the positive x direction, B is changing so that ... well, to make a long story short, I think the result is a helix on a cylinder, but the cylinder (whose axis is the z axis) is flattened in the x direction (?). Case B: braided (twisted) field lines. In this case, if one starts with vB in the positive z direction, then if the field lines curve around each other going in the postive z direction in the same direction as vp, then vp is less than otherwise, vB is more than otherwise, and the result is a helix on a cylinder (??) with a larger radius than otherwise for the same velocity in the x-y plane. If B is twisted in the opposite direction, the cylinder would have a smaller radius for the same velocity in the x-y plane. 5. Change in direction of B along B (curved field lines) This one is trickier to visualize... Locally one may consider approximately constant field strength and field line curvature; but when the radius of curvature is small enough or the range of positions large enough, constant curvature of field lines requires change in field strength along field lines, while constant field strenght requires increasing field line curvature toward a center of curvature, unless field direction is also changing as in case 4. above. --- There are someone conically shaped regions above each polar region; With B directed from the south pole to the north pole, if one visualizes the Earth with north pole pointing up, then within the ~ conic regions, B is downward, while outside the ~ conic regions, B is upward; B should increase in field strength toward the Earth. Thus, protons should have a net westward and electrons a net eastward drift especially outside of polar regions due to effect 2., many are 'repelled' from the poles due to effect 3. Effect 5 will also come into play (not sure of effect); 4, or at least 4B, is not a feature of a basic dipole field but I suppose it might occur due to disturbances or to the motions of charged particles themselves (and also within the core?).
  7. Patrick Sorry, I have read your argument a dozen times trying to see your logic but I simply can't. I am afraid it's too abstract for me.
  8. "I have read your argument a dozen times" Wow! Thanks for the effort! I suppose it would have been helpful if I had written a summary. TIDES ON EARTH: Outside of oceanic effects (and maybe a few glaciers at sea level), too weak to expect a significant effect on: 1. mantle convection and the overall rate of plate motions (which can't change fast anyway). 2. earthquakes and volcanic activity - at least in the longer term trends (as opposed to variations over cycles of 1/2 day, day, 1/2 month, month, etc.), if not even in those shorter term cycles. 3. the Geodynamo and outer core motion 4. the atmosphere, ionosphere (including E-region dynamo, in the base of the thermosphere), and magnetosphere (except in the magnetotail at those times of the month when the moon actually would get near or intersect it, although even then, on further reading it seems the magnetic forces on charged particles with the kinds of energies involved would overwhelm gravitational effects - and also, outside of the monthly and ~18-year cycles, what effect could that have, and even then, what would the significance of that be to Earth?) And where the tides have a significant effect, how would that effect relate to climate changes over a ~100 year period (as opposed to a ~ 20 year period or especially a 1/2-month (spring to neap to spring again)period)? TIDES CENTERED ON SUN (due to planets): far too weak to expect significant effect on: 1. solar convection or solar dynamo, and hence, 11-year sunspot cycle, other related phenomena including TSI variations 2. solar wind and interplanetary magnetic field (except, for effects on Earth, perhaps when Earth get's near the wake of Venus or Mercury, - **although most of that effect wouldn't actually be from the gravity of Mercury or Venus - and what effect could it be?) - this is especially considering the case considering the much much larger variations that do occur in solar wind density and velocity... TIDES ON SUN VS 'SOLAR JERK', FAIRBRIDGE CYCLE: I had thought that if the there was a correlation of solar TSI or solar wind and magnetic field to the solar jerk, it would be because they would both be correlated to the tides on the sun, which might have an effect on solar TSI, wind, and magnetic field (though an insigificant effect for our purposes, from my reasoning). The solar jerk is just the changing free-fall of the sun so it is hard to see how that would affect solar activity (as I explained elsewhere). However, it is interesting that while both such tides and 'jerk' depend greatly on Jupiter, the jerk depends also on the other gas giants due to their mass and distance, and the contribution of the 4 inner planets is tiny in comparison, whereas the three most important planets after Jupiter for the tides on the Sun are Venus, Earth, and Mercury. ---- ... Further reading on magnetosphere, solar wind...: (PS I have only browsed many of the following, with one noted exception): but of course one must be careful with wikipedia (their article on tides suggests the human menstrual period could be an evolutionary artifact of distant sea-dwelling ancestors' adaptations to tidal cycles, when in fact this doesn't seem likely at all, particularly considering the menstrual cycle periods of our closer relatives - it is just a coincidence) - on the other hand, it is possible to figure out whether or not the math and physics work out as such. But also: (which I have read completely) ----- On a possible connection of oceanic tides to climate: I think there was a related article to the above, which focussed on a correlation of shorter term variability to oceanic tidal forcing. I haven't read through these closely enough to see just how much variability in tidal forcing there is relative to the tidal forcing itself - the largest I do expect is the spring-neap variation, but there are other variations... but I expect they are smaller especially in the long term variations - so I am arguing that oceanic tidal variations are significant in climate variations on the multidecadal to century to millenial or beyond timescale, but it is interesting to consider. I don't think the authors would or could argue that this could account for the warming of the last few decades...
  9. ... aside from that: 1. Unclear that recent changes in Earth's magnetic field are anything unusual over the same time period in which recent climate changes are unusual. (**PS I'd be curious to see if the previous changes in magnetic field, either in strength of dipole or actual reversals, correspond in any significant way with the paleoclimatic record, or anything else. One would think it could affect some species (birds, turtles?), though there is no evidence of enhanced extinction rates during reversals, as far as I know). 2. While new discoveries are made about submarine volcanic activity, there hasn't been a discovery of temporal changes in this, either significantly correlated to ENSO or other climate variability, or to global warming, and the same for volcanic activity in general - (except perhaps for the going into and out of a ~quiet period with respect to explosive volcanism above water, which wouldn't explain global warming of the last 100 years but apparently has influence (But not control) over ENSO). 3. As far as I know, the torques on Earth that contribute to two of the Milankovitch cycles do not result in true polar wander - the rotational axis changes orientation but the whole body of the Earth shifts with it, so the North pole remains in the Arctic over such cycles. 4. anthropogenic greenhouse forcing may be a little less than 2 % of the total greenhouse 'forcing' (including water vapor and clouds), but the small size of that proportion may not mean what some may think; a total forcing (greenhouse + albedo) that in terms of globally averaged radiative forcing would be somewhere between 3 % and 5 % of the same total greenhouse 'forcing' accounts for the global warming between the last ice age and preindustrial climate.
  10. Patrick Much better, thank you. Re: 1 Magnetic orientation for birds etc. may simply be lines of force rather than a true polarity orientation. A reversal likely has little effect but shift does to some extent, I would not expect extinctions however. Re: 2 I disagree here. But as with any hypothesis there is room for doubt. This is under study so I am content to wait on the outcome. Re: 3 The pole remains in the Arctic yes but the amount of direct sunlight changes with the angle of attack. Re: 4 I am uncertain of this, which is why I am here.
  11. Quietman, "Re: 3 The pole remains in the Arctic yes but the amount of direct sunlight changes with the angle of attack." Yes - this much is a widely understood aspect of Milankovitch cycles. "Re: 2 I disagree here. But as with any hypothesis there is room for doubt. This is under study so I am content to wait on the outcome." If you could find articles which specify changes in time (of geologic activity, aside from major eruptions above water, of course) correlated with any climate changes on the scale of years to millenia, I'd very much like to see it. Clarification - as I recall now, there was some speculation about possible temporal changes in geothermal heating of ice at two locations - somewhere in northern Greenland, and somewhere in West Antarctica. In each case it appeared to be only speculation, though. And I don't think those could have enough regional or global significance to account for much of recent climate changes. (With all the volcanos in the world, certainly a few could just happen to change just as anthropogenic emissions are becoming a big player, but it would seem quite a coincidence if enough volcanos in the right areas happened to change activity to have regional and global climatic significance at this time and yet not for some longer period of time prior to now (as inferred by paleoclimatic records and ice sheet conditions, etc.))
  12. Patrick You still assume AGW is a big player and I do not. See the sensitivity thread.
  13. ... will post response at:
  14. Satellite Data Reveals Extreme Summer Snowmelt In Northern Greenland ScienceDaily (Oct. 10, 2008) — The northern part of the Greenland ice sheet experienced extreme snowmelt during the summer of 2008, with large portions of the area subject to record melting days, according to Dr. Marco Tedesco, Assistant Professor of Earth & Atmospheric Sciences at The City College of New York (CCNY), and colleagues.
  15. Interesting article. Is meltwater perculating up from below to heat the ice? Geothermal heating would melt the bottom first; even with infinite thermal conductivity, the melting point of ice is lower at higher pressure. Depending on the thickness of the ice at that location, it might take considerable time for a change in heating to propogate upward. I think a majority is from AGW.
  16. Patrick In the Greenland thread I have added an abstract that is applicable in answer.
  17. PS I posted a link in comment 267 in Arctic sea ice melt - natural or man-made? which is also applicable as a response.
  18. correction: comment 257 (not 267).
  19. Patrick In other words it would appear that the arctic is subject to some very unusual weather causing much of the problem for the past half century. The question now becomes, what caused the change in pattern. My tectonic argument based on "the solar jerk" offers an explanation for this change while the IPCC argument does not.
  20. "My tectonic argument based on "the solar jerk" offers an explanation for this change while the IPCC argument does not." 1. But the 'IPCC argument' (also the argument of many others) may very well explain it... (more on that later) 2. How 'on earth' is the tectonic argument linked to the solar jerk? a. is it that tides, which may be correlated with solar jerk, are acting on either the geodynamo or tectonics or volcanism (all of which I strongly doubt (tidal variations weak, variations over relavent time periods weaker still), outside butterfly effects that take time and are not discernable as predictable links among individual causes and effects)? or b. that solar activity affects Earth's magnetic field, which of course does happen, BUT - I am very doubtful (with the same caveats as in a.) of any significant role of solar jerk or tides on the sun in changing solar activity, or of any significant link between changes in the outer core geodynamo and tectonics on the relavent timescales (mantle is very slow and reacts very slowly to changes in outer core convection), or of much effect, at least on the relavent timescales, that solar and space 'weather/climate' perturbations on Earth's magnetosphere and E-region dynamo could have on motions and magnetic field in the core, considering how much much much more massive the core is and how much more intense the field is in the core (yes, there is a lot of momentum and energy per unit mass in the magnetosphere, but still I expect much more total momentum and kinetic energy within the outer core), and also that, at least as far as I know, the strongest (relative?) perturbations of the magnetic field due to space weather occur at greater distances, where the field is even weaker still. ------------ Back to 1: Greenland article abstract (referenced in comment 66): the effect of meltwater is to lubricate the base of the glacier causing faster flow; sudden changes can occur as water flows. Effect may be limited. Nowhere does it state that the meltwater has increased due to geothermal heating - not that that's not a possibility but - without actual eruptions or sudden magma movement up through cracks, changes in geothermal heating must be slow - could it account for a significant change over only decades? How much heat would be necessary to account for the amount of water melting? Wouldn't there be some indication of volcanic activity (from a pattern of earthquakes (discernable from icequakes or quakes due to changing ice mass and isostatic adjustments??); sulfur concentration in meltwater outflow????)... I think this phenomenon of basal lubrication of the ice is not limited to the area where a underlying hotspot is thought to be. --- Arctic sea ice loss article: "Rising Arctic Storm Activity Sways Sea Ice, Climate ScienceDaily (Oct. 6, 2008)" What I got from that is: There was an expectation from climate theory ("derived from model results") that a warmer climate would lead to a northward shift in storm tracks and increased storminess in the arctic. This expectation has been verified from the observations. Observations also indicated that the changing circulation patterns have affected, through wind, the Arctic Ocean circulation, via movement of sea ice. Transport of sea ice: "The team found that the pace of sea ice movement along the Arctic Ocean's Transpolar Drift Stream from Siberia to the Atlantic Ocean accelerated in both summer and winter during the 55-year period." "Progressively stronger storms over the Transpolar Drift Stream forced sea ice to drift increasingly faster in a matter of hours after the onset of storms." (I'm not sure how similar this flow pattern is to the flow of ice associated with the 2007 circulation anomaly that pushed warmer air into Siberia - in that case, however, the atmospheric circulation pattern was not unprecedented, but resulted in record minimum ice because it was acting on top of an overall warmer atmosphere and thinner sea ice, etc. - because of ongoing global warming. There will be highs and lows; on top of an upward trends the highs and lows with both be higher, except potentially for the trend's effect on the shorter term variability itself.) Ocean mixing: "The moving sea ice forces the ocean to move which sets off significantly more mixing of the upper layers of the ocean than would occur without the "push" from the ice. The increased mixing of the ocean layer forces a greater degree of ocean convection, and instability that offers negative feedback to climate warming." That last part is potentially great! - that more CO2 might go into the oceans - BUT it is also potentially worrisome - will it speed up ice loss? Will it make it harder for new ice to form each winter as the fresher meltwater is mixed into the saltier water? - and of course because of the ice albedo feedback?
  21. Patrick But in fact the thinned crust is the northern end of Greenland (in the articles linked in this thread) and surrounding Arctic ocean and that is exactly where the largest glacial melt is AND IT IS FROM THE BOTTOM.
  22. Ice albedo will remain until all the ice is gone. Soot in the top layers lower the albedo so fresh ice will have a higher albedo if we control the output of soot.
  23. They do not say if it is AGW either. In fact they do not say why at all (in that article). But top down melting would not produce the same results, nor would it be restricted to only northern Greenland where the crust is thin (they DO describe it as a "hot spot" in the other article and suggest that vulcanism is a "contributer" in an earlier article. I do think they are at last on track.
  24. Patrick Keep in mind that while you and I can speak openly for or against the AGW concept. there are others who need to be politically correct or they will lose their jobs or grant money and therefore skirt the issue. Then there are those, like one poster at this site, that are environmental fanatics who look upon AGW as a bible thumper looks to the word of God. Hopefully we will get to the truth behind all this regardless of their attempts to "enlighten" us "deniers" (that is their demonization of skeptics vocabulary, not mine).
  25. Patrick To save time and server space, I ask you to read the comments in "Arctic sea ice melt - natural or man-made?" as that is where I presented my hypothesis en todo. It technically should have been placed here, but I got angry and a little carried away when I got double teamed. But there were some good points made by all in my opinion.

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