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Climate Hustle

Two attempts to blame global warming on volcanoes

Posted on 18 January 2010 by John Cook

There are a number of skeptic arguments against man-made global warming, many of which are mutually exclusive. You can't blame global warming on the sun one day, El Nino the next day and CFCs the day after, all the while claiming global cooling is occuring although this is in doubt because of suspect surface measurements. One hat thrown into the ring of global warming culprits is volcanoes. In fact, there are two volcano arguments, each mutually exclusive. One alternative is that volcanoes emit more CO2 than humans. The other is that a drop in volcanic activity caused global warming. So both volcanic activity and a lack of volcanic activity causes global warming. Way to cover your bases!

First, let's look at the argument that volcanoes emit more CO2 than humans. Volcanoes emit CO2 both on land and underwater. Underwater volcanoes emit between 66 to 97 million tonnes of CO2 per year (Morner 2002). However, this is balanced by the carbon sink provided by newly formed ocean floor lava. Consequently, underwater volcanoes have little effect on atmospheric CO2 levels. The greater contribution comes from subaerial volcanoes (subaerial meaning "under the air", refering to land volcanoes). Subaerial volcanoes are estimated to emit 242 million tonnes of CO2 per year (Morner 2002).

In contrast, humans are currently emiting around 29 billion tonnes of CO2 per year (EIA). In other words, human CO2 emissions are over 100 times greater than volcanic emissions. This is apparent when comparing atmospheric CO2 levels to volcanic activity since 1960. Even strong volcanic eruptions such as Pinatubo (which emitted around 42 million tonnes of CO2) had little discernable impact on CO2 levels. In fact, the rate of change of CO2 levels actually drops slightly after a large volcanic eruption, possibly due to the cooling effect of aerosols.

Figure 1: Atmospheric CO2 levels measured at Mauna Loa, Hawaii (NOAA) and Stratospheric Aerosol Optical Thickness, a measure of volcanic activity (NASA GISS).

In fact, the cooling effect of a volcanic eruption leads to the second argument of how a drop in volcano caused global warming. Volcanoes emit sulfate aerosols which reflect incoming sunlight, cooling the planet. A large volcanic eruption such as the Pinatubo eruption in 1991 can have a global cooling effect of 0.1°–0.3°C for several years (Robock 1994, Zielinski 2000). However, mega-eruptions or a series of large eruptions can have a cooling effect that take decades to wear off, giving a perceived warming effect. Zielinski 2000 studies past volcanoes, particularly over the past few centuries:

Figure 2: Changes in optical depth from 1880 to 2000.

Zielinksi concluded "the lack of any climatically effective volcanism in the period 1920s to early 1950s undoubtedly contributed to the overall warm conditions during those decades." (Zielinski 2000). This is confirmed by Hegerl 2003 who found that "early 20th century warming is attributed to a composite of greenhouse warming, an uncertain contribution from solar forcing, and a recovery from a previous period of heavy volcanism".

Similarly, Bertrand 1999 found that "the lack of volcanism during the period 1925-1960 could account, at least partly, for the observed warming trend in this period". Bertrand was investigating the effect of solar and volcanic influence on climate and concluded "these are clearly not sufficient to explain the observed 20th century warming and more specifically the warming trend which started at the beginning of the 1970s".

In short, a lack of volcanic activity had some part in temperature rise over the first half of the 20th century. However, it has had little to no part in the modern global warming trend that began in the 1970's. On the contrary, relatively frequent volcanic activity in the late 20th century may have masked some of the warming caused by CO2.

So we have two skeptic arguments seeking to blame global warming on volcanoes. One says volcanic activity caused global warming. The other says a lack of volcanic activity caused global warming. The two arguments have one thing in common - they're both woefully inadequate in establishing a link between volcanoes and the last few decades of global warming.

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Comments 1 to 48:

  1. Very well done, John. There are additional variants on this too, like the claim that submarine volcanoes in the Arctic Ocean are responsible for the decline in sea ice (you can see this from time to time on WUWT), or the claim that because the oldest CO2 measurement station is on the side of Mauna Loa, CO2 isn't actually increasing at all, it's just local contamination.

    Anyway, lacking your patience I usually see claims that "volcanoes are the real cause of AGW!" as evidence that the person making the claim doesn't have enough common sense to justify my participation in a serious discussion.

    But it's good to see that not everyone shares my impatience. This site is fantastic, and I've recently taken to directing people over here whenever I run across another version of the standard "un-skeptical skeptic" talking points.
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  2. @ Ned Yeh the Mount Loa comment is pretty hard to shake off. A point to highlight to those that make this claim is the lack of a spike in the data last time it erupted (84) and the fact that the volcanoe has been overall less active than normal over the following quarter of a century, and as such if the readings were contaminated by the site then the data should have shown a corresponding decline.

    I don't doubt that the current data is calibrated against other sites in the NOAA network as well as secondary observations from sources like weather balloons.
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  3. Here's a paper discussing the detection and removal of local co2 emissions from the Mauna Loa ('mount' obviously, but get better search results when you that term) record. Basically it states that localized co2 from the vents is at a completely different concentration and not mixed with the surrounding air and as such easy to distinguish from the background. It also notes that it is variable minute by minute - were as background data is steady over hours.
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  4. Thanks, 70rn. It's even simpler to point at all the other CO2 monitoring stations that have been set up elsewhere:

    Just as an example, I clicked on "Data / Quick Plot", then "Barrow" (Alaska), then "CO2 (continuous)", then chose Monthly data "File / Quick Plot", and plotted the result as a PNG. Lo and behold, a nice rising trend in CO2 from 1973 onward, with a strong seasonal cycle, too.

    I don't know of any volcanoes at Point Barrow, and I am unaware of any volcanoes that belch CO2 with such a nice, smooth, consistently rising trend over three decades!
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  5. Yeh? Well it's nice to have that off the list of arguments. All we have to do now is minutely scan every centimetre of the sea floor for volcanoes, (who are there in their millions apparently, pumping away in vast numbers with out changing the temperature profile or acidity of the ocean significantly, which is thoughtful) and you might even cause some ambivalence on this issue in a few heads.
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  6. I am very facinated by the Mount St. Helens explotions in 1980. To me it was big.However is not at the graphics. Is it as mistake ? Do you have a listing of vulcanoes by size ?
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  7. Klaus, the site urled just below has a list of all of the major known volcanic eruptions of the Holocene (having Volcanic Explosive Index of 4 and higher). If you click on each volcano in the list it gives you detiled information about known properties. You might get some info there as to why St Helens isn't on the graph. It was a pretty major explosion, but perhaps it didn't have a large effect on very high altitude transmission of solar radiation..???

    70n, a very quick way of assessing the Mauna Loa record is to compare it with the record of CO2 averaged over the sea surface sites. The data are continuously updated at the NOAA Mauna Loa site. The Mauna Loa record is very similar to the record of the sea surface average:
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  8. Klaus, you may find this article helpful:
    On page 192 there's the following statement: "While the
    Mount St. Helens eruption of 1980 was very explosive, it
    did not inject much sulfur into the stratosphere." There's also a table on the same page comparing historic eruptions and the various indices used to measure the intensity of the eruptions and their effect on climate.
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  9. Is there any data on underwater volcano eruptions? An argument that seems to be popping up more and more is that global warming is driven by underwater volcanoes that (1) warm the oceans, which (2) in turn warm the athmosphere.

    Is there any data about whether this can be ruled out? I think the appeal of this argument comes from
    a) that underwater are supposedly hard to track (so a large scale increase of eruptions could be going on without our knowledge)
    b) several recent papers arguing that part of the recent warming is driven by the oceans.

    It did some searching and could not find anything on this hypothesis, although I am sure it must be out there.
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  10. This is a thing that continues to cause me a headache:
    The Early 20th Century(1900s-1940s) Warming of 0,4 ºC.

    It seems to me a lot strange that it peaked in the 1940s (then followed by a slight cooling of -0,1ºC until the 1970s) when both:

    a)Solar Activity peaked in the 1960s
    b)Big volcanos erupted(after near 50 years of calm) in the 1960s

    So, why Temperatures peaked in the 1940s and not in the 1960s?

    My suspect were Tropospheric, man-made AEROSOLS, but after seeing the GISS graph, TOTAL forcing still peaked in the 1950s at 0,5 W/m^2, still A DECADE(1950s) AFTER TEMPERATURES BEGAN TO COOL!

    What is going on?
    It could be:

    1)Errors in temperature data or in the GISS total forcing estimation(this second is more likely as Aerosols Forcings are still considered "highly uncertain")

    2)Climate Variability masking the (warming)forcing in the 1950s (for example, a series of weak El Niños and strong La Niñas)

    What do you think?
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  11. Paz, the heat coming from undersea volcanoes along with the entire rest of the crust of the Earth (0.09 watts/m^2), is tiny compared to the forcing from CO2 (2.66 watts/m^2). For details, see my comments
    #234 and the following #235 in the Skeptic Argument Volcanoes emit more CO2 than humans.
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  12. Geothermal Heat emission = 0.09 watts/m^2 ?

    This is 10% of our measured Radiative energy imbalance of 0.9 watts/m^2!

    Where do you get this data?
    10% seems too much!
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  13. To add to Tom Dayton's comment..although this is to do with CO2 emissions rather than heat from undersea/submarine volcanoes the US Geological survey has a comparison of CO2 emissions from volcanoes vs. human activities.

    ...Human activities release more than 130 times the amount of CO2 emitted by volcanoes--the equivalent of more than 8,000 additional volcanoes like Kilauea...
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  14. Tom Dayton:

    Remember that the difference between Solar Maximum and Solar Minimum TSI is near 1 W/m^2 .Taking into account the Spherical Surface of the Earth, this gives us a forcing of 0,25 W/m^2.

    Now 0,09/0,25 = 0,36 ... 36% of Solar Variability!

    If your data is true, it can be an important Climate Forcing on geological timescales!
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  15. Thanks Tom, very interesting. Do you know of any charts that track recent the amount of underwater volcano eruptions over the recent decades?
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  16. From Peru, I got the data from the sources I listed in the comments I cross-referenced in my previous comment. Where I wrote "For details, see ....". You should read first, type second.
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  17. From Peru, the forcing from solar minimum and solar maximum is zero. Because the min and max cancel each other out, over every 11 years.

    And geological timescales are irrelevant to the past 150 years in which human-induced warming has been most pronounced.
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  18. Sorry, Paz, I don't remember. Look at the comment I cross-referenced earlier, and click on the links you find there; they might have what you're looking for. Otherwise I suggest looking at the U.S. Geological Survey web site.
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  19. Another way of addressing your question Paz, is to examine the vertical distribution of enhanced ocean heat in a warming world. The time variation of enhanced heat will be quite different if the heat penetrates the ocean from the atmosphere, compared to the notional situation of enhanced undersea volcanic activity (a notion which completely lacks evidence - one would have to postulate that undersea volcanic activity has all of a sudden increased by a truly vast amount).

    There's a fair amount of analysis of enhanced ocean heat distribution, and this is consistent with ocean warming as a result of heat penetration from the atmosphere. A "classic" paper is this one, downloadable from the link below (there's quite a bit of more recent studies too...):

    Barnett, T. P. et al. (2005) Penetration of Human-Induced Warming into the World's Oceans Science 309, 284-287
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  20. From Peru,
    on a geological time scale even land volcanoes may have a role, as probably happened in the deep past and on a much smaller scale in the last century. But it's irrelevant for recent global warming, what matters is what changes, not what is constant.
    One more point, as Gavin Schmidt said a while ago answering a question, underwater volcanoes would warm the deep ocean more than the surface, which is not happening.
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  21. a few minutes too late, and chris's answer is more detailed ;)
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  22. re #12 From Peru

    The apparent dichotomy of the apparently quite sizeable geothermal heat flux (0.09 W/m^2) compared to the radiative forcing from CO2 (0.9 w/m^2) is resolved by noticing that the geothermal flux isn't a forcing. The geothermal flux is the background stationary level of heat flow from the interior, and since this has been proceeding for millenia and more into the deep past, the earth's ocean/surface temperatures will be near equilibrium with respect to the geothermal flux (unless it has changed massively in reecent times). So the forcing is near zero.

    It would be more appropriate to compare the geothermal flux (0.09 W/m^2) to the total solar flux averaged over the earth surface (1370/4 W/m^2).
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  23. re the TP Barnett et al paper in my post #19 above. The url corrupts when pasted here (perhaps John Cook can fix it!).

    You can find the downloadable pdf by Googling using the search term:

    Penetration of human-induced warming into the world's oceans. Barnett TP

    The link to the pdf will be high up on the list of results...
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    Response: I've fixed the link in Comment #19. What I think happened was you copied and pasted the URL from the google search results. The problem is google abbreviate the URLs that they display in the search results (hence the /../ peppered through the URL). You need to click on the link then copy and paste the full URL from the browser's URL bar.

    BTW, thanks for posting that paper. When I get around to the "heat from underwater volcanoes are causing global warming" argument, Barnett et al is a key part of the answer.
  24. Even if the current trend in global warming is actually anthropogenic, (and due solely to CO2 emissions), all it takes is one huge natural disturbance, or change on the part of nature to make anthropogenic forcing completely irrelevant (at least for a time).

    Or is this not conceivable?

    On the other hand, as per chris #22, even if the Earths temperature did rise 10 degrees for 500 years due to a comet, you would still have to baseline the problem from the new mean, and consider only extra forcings due to CO2 and sunlight. In other words, Paz, it doesnt matter how much heat is coming from the bottom of the sea due to hotspots and fissures.
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    Response: Man-made warming is not due to CO2 emissions only - there are also warming contributions from ozone, methane, contrails, nitrous oxide, CFCs. But the warming from CO2 is both the strongest forcing and the fastest rising.
  25. RSVP writes: Even if the current trend in global warming is actually anthropogenic, (and due solely to CO2 emissions), all it takes is one huge natural disturbance, or change on the part of nature to make anthropogenic forcing completely irrelevant (at least for a time).


    Even if you've saved up scrupulously for retirement, a large comet hitting the Earth would wreck the economy and eliminate your retirement savings. So there's no point in saving for retirement.

    Seriously, what is your point?

    As far as I can tell, every single one of your dozens of posts here consists of rather transparent attempts to justify not doing anything serious about reducing our impact on the climate system.

    But this one just seems ridiculous. We shouldn't bother doing anything to reduce our CO2 emissions because some mysterious catastrophe could happen suddenly and render all our work irrelevant?

    That logic could be used to argue against doing anything about anything. Why bother getting out of bed in the morning, when you could be hit by a streetcar on the way to work?
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  26. Ned,
    Actually what you are trying to say is that if CO2 is no the real culprit, climate scientists have nothing to do. And therein lies the bias.
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  27. By the same token, RSVP, if CO2 is the real culprit (as all the evidence seems to suggest), then reducing CO2 emissions will require significant cuts in our use of fossil fuels-which will in turn hurt the profits of the companies that mine & refine these fossil fuels. Is it any wonder, then, that a great deal of the anti-AGW bias is coming from individuals & groups with such strong links to the fossil fuel industry?
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  28. Another point, RSVP, is that if CO2 is not the real culprit, then this actually provides a whole new mystery for climate scientists to solve, thus giving them *loads* to do-both in determining the real culprit & trying to model the impacts of this new cause on future climate change. Indeed, a new culprit for climate change might require *more* scientists, not less, to pore over all the existing literature to try & get a handle on the real culprit. Second to this is that climate scientists existed before global warming became an issue, & would still exist if the whole thing proved to be a furphy, so your whole argument is really quite weak!
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  29. Thanks a lot, Chris. Very helpful.
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  30. Marcus,
    There appears to be a small flaw in your reasoning #28. If global warming in NOT anthropogenic, it would suggest there is not a lot we can do about it. Yes, we can prepare for it, but we cant change it.

    One of the most irresponsible notions I have seen on this website come from those who are not willing to place the blame on overpopulation, especially when they support the theory that global warming is anthropogenic. If it is anthropogenic, it is because there are just too many anthropoids!
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  31. Ned.
    Your post 25 is one of the best, as it actually points to the way forward. If we all did just stay in bed, maybe the environment would have hald a chance.
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  32. RSVP writes: There appears to be a small flaw in your reasoning #28. If global warming [is] NOT anthropogenic, it would suggest there is not a lot we can do about it. Yes, we can prepare for it, but we [can't] change it.

    Well, as amply documented on this very site, anthropogenic CO2 (plus CFCs, N2O, etc.) are changing the climate. So I don't see much point in arguing over a counterfactual.

    It's as if I said "Since much of Nevada is arid or semi-arid, water conservation is important" and you replied "Well, if it started raining a lot in Nevada, it would suggest that they didn't have to worry about water conservation."

    That may be a logically true statement, but it's not relevant to our world and it would be exceptionally foolish to accept that kind of reasoning as justification for stopping all water conservation efforts in the Great Basin tomorrow.
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  33. RSVP

    Sorry, can't help it:

    "If it is anthropogenic, it is because there are just too many anthropoids!"


    "If we all did just stay in bed, maybe the environment would have had a chance. "

    Separate beds, presumably.
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  34. Thanks to Chris for post nr 7.

    From the link you gave, I have found that the Tephra Voulumen is about 100 times larger for Pinatubo than for St Helens. This explains the lack of fingerprints from St Helenesin the carbon emission.
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  35. There is no logical flaw RSVP, for these reasons:

    1. If CO2 were not the culprit, then knowing the real culprit-& how it changes the climate-could reveal a means of counteracting it.

    2. By understanding the cause, we might also get insight into future effects-thus making adaptation much more successful.
    So you see, plenty of work for climatologists, regardless of whether CO2 is to blame.
    My other point is that *of course* we need to deal with overpopulation, resource depletion & general environmental degradation but (a) last time I checked, we were quite capable of "walking & chewing gum at the same time", as it were & (b) tackling many of the above problems dovetails very nicely with tackling rising CO2 emissions. e.g. reducing urban sprawl will allow more land to be maintained as forest or re-vegetated & will significantly decrease our consumption of a significant non-renewable resource-oil-both of which just happen to be outcomes which will result in REDUCED EMISSIONS OF CO2. Unfortunately, those who are most stridently opposed to the concept of AGW are also those pushing for ever greater population growth-because the ultimate outcome is the same-MORE PROFIT. If you want to understand the motives of the die-hard denialists, RSVP, you need only "follow the money".
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  36. All the various factions arguing about action keep on repeating that we need more "studies" and more evidence on AGW. Seems to me they're the one wanting more work for climatologists...
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  37. This is similar to the TSI article earlier.

    We have multiple factors affecting global temperatures. If you try to take one of those factors such as volcanism or CO2 concentration and find a perfect relationship with global temperatures your going to fail. At certain time periods the relationship will breakdown and that can be highlighted to rubbish any connection.

    Do we believe that volcano activity has an overall affect on global temperature? It must do something (positive, negative or no overall affect). To highlight the lack of consensus on exactly what volcanos do is to just show how we need to improve our knowledge on this subject. Can we be concrete on our understanding of CO2 affect on global temps when we can't control for all the of factors affecting temp.
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    Response: I wasn't highlighting the lack of consensus among scientists - I was pointing out the lack of consensus among skeptics. Skeptic arguments may contradict each other but they all have one thing in common - sow doubt so as to delay action on cutting carbon emissions.

    We do have a fairly high degree of understanding of how volcanoes affect climate. This was demonstrated when Mount Pinutabo erupted. It gave climate scientists the opportunity to predict how global temperatures would respond to the injection of sulfate aerosols in the atmosphere. Hansen 2007 compares the model predictions to actual observations, shown below. The model results also confirmed the climate's net positive feedback - as temperatures cooled, water vapour in the atmosphere lessened which amplified cooling.

    Comparative plots of optical depth and observed and simulated global mean temperature
  38. How can I post IMAGES?

    I have some beautiful graphs, but when I tried to "cut and paste" (that is, to "paste" the graph in the comment) the graph didn't appeared.

    What should I do to post graphs or any other image?
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    Response: I would suggest uploading them to a free image website (does Flickr let you do that kind of thing) then use the HTML IMG tag <img src=> to display the image in your comment.
  39. H.R.there is no lack of consensus among scientist on the climatological effects of volcanic activity.
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  40. John Cook: About early XX century warming (1910s-1940s):

    Given that:
    -TSI peaked in the 1960s.
    -Major volacnic eruptions began in the 1960s with Mount Agung.
    -NASA GISS estimates that TOTAL FORCING peaked in the 1950s at near 0,5 W/m^2.

    But temperatures peaked in the 1940s, then slight cooling began until the 1970s (while the forcing continued to grow up until the 1950s-1960s)

    Any idea why temperatures peaked ONE DECADE BEFORE (the 1940s) the total forcings (according to NASA GISS) peaked in the 1950s?
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    Response: Perhaps part of the effect you're looking at is explained by problems with sea surface temperature measurements in the 1940s. When all forcings are considered (the pink bar in the figure below), they show a close match with land temperature. The forcing does seem to reverse slightly after temperature reverses but is within uncertainty bounds. However, in the 1940s, the ocean temperature falls well outside model uncertainty bounds. The paper A large discontinuity in the mid-twentieth century in observed global-mean surface temperature (Thompson 2008) explains that this is due to a change in the method of measuring ocean temperature in the 1940s which caused a spurious warming signal. As far as I know, the global temperature record still hasn't been updated to adjust for this effect.

  41. It is an interesting possibility, but this graph:

    Shows that the discrepancy is GREATER IN LAND than in the Global Oceans.

    Whatever the cause is, this strange behaviour ONLY occurs in NORTHEN LATITUDES(23,6ºN-90ºN):
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  42. From Peru. Just a possibility, but could this maybe be the result of a lack of data from the USSR during at least some of this period? I'm not saying this is the case, merely hypothesizing.
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  43. Volcanic activity releases more water vapour than any other gas (up to 95% of the total gas discharge may be WV) and submarine/coastal lava flows produce localized highly acidic conditions (pH ~ 2.0).
    Given that the estimated total atmospheric release of CO2 from volcanic activity is ~ 130million tons then a conservative estimate of WV released would be ~ 400 million tons, which I suggest would have a greater immediate effect (but shorter lived) than the CO2.

    Some background stuff here:
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  44. - maybe we dont have to worry about climate change because the Earth uses Volcanoes as a mechanism to cool down the Earth if it is getting to hot. We like to think we are more important than we are. We think it must be caused by humans because this global warming trend has happened in a relatively short period compared to other climate change historically.

    Its really hard to take into account all the possible variables like solar or lunar events, or anything natural that we are unable or haven't yet studied. There is a hysteria about this current media fad and that makes me suspicious. It doesn't sound scientific and the facts are Never fully released just the conclusions. Scientists are not the most biased people I know. They have careers to protect as well as ego.

    Also one study has shown that CO2 emissions on land have no bearing on climate change and that it is actually sea temperatures rising that is causing the changes on land. Therefore underwater volcanoes could be one of the causes of the rise in sea temperature or other natural causes. I am sure there are other studies out there.
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  45. tinsol,
    strong volcanism has a cooling influence, no doubt. But i'd not call it "a mechanism to cool down the Earth if it is getting to hot". Volcanism follows its own rules, unrelated to surface temperature. It can not "react" to warming or cooling.
    Underwater volcanism could in principle produce a warming of the oceans, but hypothesis need to be confronted with reality. Up to now no one could find any evidence for it, either direct (the known underwater volcanoes) or indirect (more warming at depth).
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  46. Gentlemen,

    I notice that most of the posts here concerning volcanic contributions to the global warming concentrate on the effects on the atmosphere. What about the heating of the ocean due to underwater volcanism

    We vacationed in Hawaii this summer and visited the Volcano Observatory there. One of the things they mentioned is that underwater volcanic eruption have increased by about 50% over the past century. And that active volcanoes have been found in the Arctic Ocean and a new hot spot has been discovered under the ice in NE Greenland where it appears to be melting the ice.

    My daughter was curious and asked the geologist how much water was in the oceans and how much heat did it take to raise the temperature of the oceans 1 degree F.

    He said that was a good question and when they worked out the numbers using the heat from Kilauea as an example. [volume of ocean, weight of ocean water, joules required to raise 1 lb of water 1 deg F, heat from lava]. We were all surprised as Kilauea puts out enough energy to raise the entire ocean by about 0.005 degree/year. Since Kilauea has been in eruption for 29 years that adds up to 0.15 degrees from a single volcano. Find 10 other active volcanoes like Kilauea world wide and you can account for most of the observed ocean warming, which is about 1.5 deg F. over the past century.

    The geologist also pointed out that current climate models do not take this energy input into account.

    Any comments?
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  47. Any comments?

    Oh, most certainly.

    For starters:

    "He said that was a good question and when they worked out the numbers using the heat from Kilauea as an example. [volume of ocean, weight of ocean water, joules required to raise 1 lb of water 1 deg F, heat from lava]. We were all surprised as Kilauea puts out enough energy to raise the entire ocean by about 0.005 degree/year."

    I'd like to see the actual "numbers" - without them, "0.005 degree/year" is just tinsel.

    "Since Kilauea has been in eruption for 29 years that adds up to 0.15 degrees from a single volcano."

    Even if your "number" is correct, your inference is not, because you did not account for any other heat flux... including, for example, the radiation and conduction of heat from the ocean.

    Big woopsie.

    There's more, but frankly I'm not sure that it's worth the bother of whacking the mole.
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  48. smoidel @46, I can do better than one volcano. The geothermal energy released over one year for the entire globe averages at 0.09 W/m^2. Over the entire globe, that represents 510*0.09*10^12 W, or 45.9 Terajoules per second. Taken over the course of the year, that is 1.45*10^21 Joules of energy. That may seem like a lot, but it must be divided among 1.3*10^18 cubic meters of ocean water, or 1.4*10^21 Kg. In other words, in each year, all energy from the Earth's interior represents just 1.04 Joules per Kg of ocean water. Given that specific heat of water is 4.187 kJ/kgK, that means in an entire year, all heat from the Earths interior could only raise the Oceans temperature by 0.00025 degrees C (0.00045 F)

    There appears to be a discrepancy between my calculation, and that of your reported geologist. Unfortunately, I do not know the energy released by Kilauea, but I do know that released by the famous eruption of Krakatoa, ie, 200 Megatons of TNT, or 8.4 x 10^17 Joules. That means one Krakatoa explosion, every hour on the hour would generate 7.4 x 10^21 Joules of energy, enough to raise the Earth's oceans temperatures by 0.002 C (0.003 F) in a year. Somehow, I just don't think Kilauea is erupting with the energy equivalent of 1.67 Krakatoa's per hour. Nor do I think that all waters within a kilometer of Kilauea are boiling continuously (which would be the case if it were).

    Going back to more realistic figures, ie, the total energy released from the interior of the Earth as determined by people who have actually studied the issue, by all means assume it has increased by 50% over the last century. It still is not enough to explain any measurable fraction of global warming. Not, of course, that under water volcanoes have been monitored for the whole of the last century so that claim could actually be based on empirical data.

    Finally, at SkS we prefer it if you discuss topics where they are most clearly related to the OP. In this case, the discussion should be here. I heartily recommend that you read that post, and if you choose to respond, that is where you should do so.
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