Volcanic CO2

From time to time we hear the claim that volcanoes inject more CO2 into the atmosphere than human activity. Its typical form is exemplified by a comment at RealClimate which was (quite appropriately) consigned to the “Borehole.”

When the volcano, Mt Pinatubo, erupted in the Philippines in 1991, it spewed out more greenhouse gases into the atmosphere than the entire human race had emitted in its entire YEARS on earth.

This claim is almost as ubiquitous as it is ridiculous, and seems to be championed by Australian geologist Ian Plimer, author of the execrable book “Heaven and Earth: Global Warming, the Missing Science.” Science seems to be missing from all of Plimer’s musings on global warming.

There’s an article in EOS by Terrance Gerlach, and a press release about it, which attempts to lay some of these myths to rest. Gerlach notes that this is a common misunderstanding, not just among the general public but among geoscientists who don’t work in this field:

The most frequent question that I have gotten (and still get), in my 30 some years as a volcanic gas geochemist from the general public and from geoscientists working in fields outside of volcanology, is ‘Do volcanoes emit more carbon dioxide than human activities?’

Gerlach doesn’t just echo the question, he answers it:

Which emits more carbon dioxide (CO2): Earth’s volcanoes or human activities? Research findings indicate unequivocally that the answer to this frequently asked question is human activities. However, most people, including some Earth scientists working in fields outside volcanology, are surprised by this answer. The climate change debate has revived and reinforced the belief, widespread among climate skeptics, that volcanoes emit more CO2 than human activities [Gerlach, 2010; Plimer, 2009]. In fact, present-day volcanoes emit relatively modest amounts of CO2, about as much annually as states like Florida, Michigan, and Ohio.

Gerlach surveys the literature and reports the scientific findings:

Global estimates of the annual present-day CO2 output of the Earth’s degassing subaerial and submarine volcanoes range from 0.13 to 0.44 billion metric tons (gigatons) per year [Gerlach, 1991; Allard, 1992; Varekamp et al., 1992; Sano and Williams, 1996; Marty and Tolstikhin, 1998]; the preferred global estimates of the authors of these studies range from 0.15 to 0.26 gigaton per year. Other aggregated volcanic CO2 emission rate estimates — published in 18 studies since 1979 as subaerial, arc, and mid-oceanic ridge estimates — are consistent with the global estimates.

Considering that human activity released some 30 Gt CO2 into the atmosphere last year, human emissions are likely 100 (or more) times as large as volcanic emissions. Those who make claims about the Mt. Pinatubo explosion emitting more CO2 than all of human activity for all time, should be made aware that the estimated CO2 emissions from Mt. Pinatubo are 0.05 Gt CO2, about the amount released by human activity in half a day, not our entire history. In fact, in less than 3 days we outstrip the volcanic emissions for an entire year:

On average, humanity’s ceaseless emissions release an amount of CO2 comparable to the 0.01 gigaton of the 1980 Mount St. Helens paroxysm every 2.5 hours and the 0.05 gigaton of the 1991 Mount Pinatubo paroxysm every 12.5 hours. Every 2.7 days, they emit an amount comparable to the 0.26 gigaton preferred estimate for annual global volcanic CO2 emissions.

Annual CO2 emissions from human activity are greater even than what results from supereruptions, volcanic events which spew forth more than 450 cubic kilometers of magma:

Supereruptions are extremely rare, with recurrence intervals of 100,000–200,000 years; none have occurred historically, the most recent examples being Indonesia’s Toba volcano, which erupted 74,000 years ago, and the United States’ Yellowstone caldera, which erupted 2 million years ago. Interestingly, these calculations strongly suggest that present-day annual anthropogenic CO2 emissions may exceed the CO2 output of one or more supereruptions every year.

Supereruptions are a significant contributor to adding CO2 to the atmosphere on geologic time scales. Yet they pale by comparison to human emissions. Yes, you read that right — while supereruptions only happen every 100,000 to 200,000 years or so, we’re presently adding CO2 to the atmosphere at a rate of one or more supereruptions every year.

Those who continue to claim that volcanic activity puts more CO2 into the atmosphere than human activity (including Ian Plimer) have been corrected — many times — by those who actually do the research. Yet the claim, like a zombie, refuses to die. Those who cling to it do so, not just out of ignorance, but out of willful ignorance.


128 responses to “Volcanic CO2

  1. spanish climatologist

    I have recently been discussing the same stupid thing (extra CO2 comes from volcanoes) with a denialist in a Spanish newspaper. I think that the source is probably wider than Plimer. I wonder whether there exist lists of resources for discussion shared by denialists. Might be it has recently appeared in one of those lists. I don’t know but we could perhaps assume that they share “ideas” (to name them someway).

  2. Because of his credentials, and the average person’s ignorance of anything to do with science, Plimer’s views have had an inordinate affect on common understanding. Without dwelling on his misinformation, counters to them need to be repeated frequently.

    Nicely done.

  3. Not sure if the original article was actually written by Plimer, but in any case the whole thing is intentionally misleading. It claims that greenhouse gas emissions from volcanic eruptions are much larger than anthropogenic emissions, when in fact the reverse is the case as you say, but more importantly it neglects to mention the fact that natural emission and absorption of CO2 are equal, so the net natural change is zero. This is clearly true from the fact that atmospheric CO2 was stable at 280 ± 5ppm for all of the last 10,000 years up to the start of the industrial revolution. Only anthropogenic emissions have been causing a net increase in atmospheric CO2.

  4. Greg Simpson

    Toba and Yellowstone are not the most recent examples of supervolcanos, at least according to Wikipedia. It lists lake Taupo, in New Zealand as the most recent VEI 8 eruption. The last major Yellowstone eruptions was 640,000 years ago, not two million.

  5. I cannot reiterate this often enough: despite frequently being touted as Australia’s most respected and preeminent geologist, Ian Plimer’s research history is not held in high regard by any geoscientist I have worked with (one of which was a co-author on one of his papers). His publication history is pretty much restricted to the Broken Hill ore deposit, and you can count the papers he’s primary author for on one hand. I’ve heard him tout himself (and his buddy Bob Carter, whom I personally know as well) as the last of a generation of geoscientists trained to be polymaths.

    And no, that is not an ad hominem fallacy, because it is a response to him, and his fan club, touting him as THE spokesperson for the geological perspective of AGW, due to his scientific credentials (which would be an appeal to authority).

  6. Plimer is the guy who thinks the sun is made out of iron (Heaven and Earth, p. 120). ‘Nuff said.

  7. Considering this myth completely discredits the deniers that make it and demonstrates their claims cannot be trusted, I actually think this particular myth is great. I think it ultimately does a lot more damage to the public’s perception of deniers than it does to climate science.

  8. Steve Metzler

    Ian Plimer is still the ‘go to’ guy at WTFUWT for a lot of their resident armchair scientists. No mystery as to why that is.

  9. It’s quite interesting that Svante Arrhenius, in his famous 1896 paper, extensively quotes geologist Arvid Högbom who estimated that the production of coal at that time, some 500 million tons or 0.5 gigatons per year in the 1890s, was of the same order of magnitude as the removal of carbon from the atmosphere by rock weathering – which Högbom rightly said is in turn usually more or less in balance with “volcanic exhalations and geological phenomena connected therewith”. So we knew already in the 1890s that mankind was emitting at least as much CO2 as volcanoes.

    The irony boggles my mind. This myth was debunked 115 years ago!

    • If you look closely at the http addresses you might notice a pattern…

      Arrhenius, Svante, 1896. On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground
      Philosophical Magazine ser. 5, vol. 41, 237–276

      Tyndall, John, 1861. On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connection of Radiation, Absorption, and Conduction. Philosophical Magazine ser. 4, vol. 22, 169-94, 273-85.

      Memoir on solar heat, the radiative effects of the atmosphere, and the temperature of space, by Richard Taylor. Scientific Memoirs 4. (1846) London. Taylor and Francis. Pgs 44-90. English translation of “Mémoire su la chaleur solaire, sur les pouvoirs rayonnants et absorbants de l’air atmosphérique, et sur les températures de l’espace,” by Pouillet, Claude S. M (1838) Comptes Rendus de l’Académie des Sciences 7, no. 2, 24-65.

      General remarks on the temperature of the earth and outer space. American Journal of Science. 32, 1-20 (1837) by Ebeneser Burgess. English translation of “Remarques générales sur les températures du globe terrestre et des espaces planétaires.” Annales de Chimie et de Physique. (Paris) 2nd ser., 27, 136-67 (1824), by Jean-Baptiste Joseph Fourier.

      The most recent article the National Science Digital Library has in this collection is:

      Santer, B. D., K. E. Taylor, T. M. L. Wigley, J. E. Penner, P. D. Jones and U. Cubasch, 1995. Towards the detection and attribution of an anthropogenic effect on climate. Climate Dynamics 12, 77-100.

      • Timothy,

        Thanks for pointing out the other papers from this great resource. I had previously downloaded only the Arrhenius paper from there and basically missed all others (and the related short essays). They have a much more concise selection of important papers (1) than what can be found on Spencer Weart’s excellent site (2), which is my primary resource for the history of climate change science.

        (1) http://wiki.nsdl.org/index.php/PALE:ClassicArticles/GlobalWarming
        (2) http://www.aip.org/history/climate/index.htm

      • Tapani,

        I hadn’t seen the index. I merely started playing with the numbers in the ip address. So much for internet detective skills! Anyway, the index will certainly be helpful, and yes, Weart’s history is an excellent resource.

      • And I’d be remiss if I didn’t acknowledge my indebtedness to the NSDL Wiki as a primary source for my articles on the history of climate science. It’s a resource for which I’m extremely grateful, and I can’t recommend it highly enough.

        (I’m also grateful to Tamino for letting me occasionally puff my articles a bit here!)

        Getting back to the NSDL Wiki, though, I find it fascinating and humbling to ‘see’ first-class minds at work with a much more limited body of information than we have today–and to see them building up that body of knowledge. “Recapitulation” may denote an embryological phenomenon, but it’s a word that can also describe a useful educational tactic! (A round-about way of saying that I’ve learned a hell of a lot from the NSDL climate Wiki.)

      • Kevin McKinney wrote:

        Getting back to the NSDL Wiki, though, I find it fascinating and humbling to ‘see’ first-class minds at work with a much more limited body of information than we have today–and to see them building up that body of knowledge.

        I believe you would have liked St. John’s College, two sister colleges, one in Annapolis and one in Santa Fe. My wife did both undergraduate and graduate school there. I did only graduate school. The Great Books Program, what they gave you was what previously might have been called a classical liberal education. You would read from Plato and Aristotle, the Greek tragedists, Euclid, St. Augustine, read The Canterbury Tale, Dante, Newton, Locke, Darwin, take Lobachevskian geometry, Kant, Hegel, constitutional law, etc.. And if you were in the undergraduate program you would learn to read some of the original Greek and French. Basically you got the chance to see Western thought an civilization as it unfolded.

      • You are probably right, Timothy!

  10. Sympathisers at the Geological Association of Canada were gullible enough to invite Plimer as keynote speaker at a climate symposium at their recent annual convention. Consequently, we are now taking suggestions for symposia for 2012.

    Prof. Ian Enting’s (Uni. Melborne) latest update of corrections to Plimer is available here.

  11. Tapani, thanks for pointing that out. I downloaded a copy of Arrhenius’ paper last night, but haven’t had a chance to read it yet. It’ll be a useful rebuttal to the volcanic CO2 argument.

    BPL: Well, I’m sure there’s a *lot* of iron in the Sun’s core, but did he really say it’s predominantly iron? Because if he did, that’s a whole lotta stupid… a simple calculation would give you the minimum mass of something the size of the sun made of iron, and that would, in turn, affect the orbits of the planets. Given the (average) density of the sun is less than 20% of the density of iron at room temperature & pressure, I think it’s rather unlikely that the proportion of iron there is large (Wikipedia tells me it’s 0.2% iron – which means about 600-700 earth masses, so quite a lot, relatively speaking ).

    Tamino – thanks for the article. I’ve had a few questions on it recently, it’ll be good to have some numbers to point to.

    • Agreed. I think this particular (or should I say ‘peculiar’) hypothesis goes back to Oliver Manual. Google him, if you care to–I’m saying no more about him here.

  12. The Sun does not produce (and will not produce in its future evolution) any iron in its core — it simply isn’t massive enough to ever achieve the high core temperatures needed to produce Fe in the core by nuclear fusion. The only (significant) fusion reactions carrying on in the solar core at present are the fusion of 4 1H atoms to a single He nucleus via the proton-proton (p-p) reaction chain, which small contributions from the CNO cycle reaction chain.

    The solar iron abundance is (by number) 3.24e-,5 or equivalently, 7.51 on the astronomer’s log NH=12.00 scale.

  13. Please ignore the gremlin that put that comma in my last line. It should read: The solar iron abundance is (by number) 3.24e-5.

  14. Steve Bloom

    I had a very vague memory that Dixy Lee Ray had a central role in propagating the volcano myth, which allowed me to turn up this Donella Meadows article laying out the whole sordid tale. The transition to CO2 isn’t discussed but would have been all too easy for such people.

    IIRC Ray played a similar role in popularizing some other now-standard denier myths.

  15. The “sun is iron” claim is not Plimer’s work but one Oliver Manuel, who has occasionally spammed academic e-mail addresses with his claims. They are trivially shown to be absurd and so the fact that Plimer reproduced them without question means that either his scientific knowledge is appallingly basic, or that he’s setting out deliberately to mislead.

  16. That volcanoes aren’t a major source can fairly trivially be shown by just looking at the CO2 record. If Pinatubo was a major source, there would be a sharp jump up when it erupted. But there isn’t.

    • Strange, isn’t it: the CO2 record fails to show those obvious huge jumps (and they would have to be huge for the fantasist claims to be credible) and instead shows a steady and smooth increase. We also know from fossil fuel consumption records that the increase we see in the atmosphere is only about half of our CO2 output. Just how do the fantasists manage to ignore these obvious points? Oh, got it: the CO2 records are a fraud, a scam, like everything else; the only reliable CO2 record is the one produced by E-G Beck.

      • Tragically, claiming frauds and conspiracy (between scientists, governments, and media) is an ultimate fallback position for some of these folks. The other fallback strategy that occasionally plays out–recently in Australia, as an example–is threatening or carrying out violence.

      • “.. . the only reliable CO2 record. . .”

        Just so. In a way, I feel that this sort of thing is an indicator of progress; the more you press a denialist with logic, the more likely they are to resort to complete nonsense. And the more complete the nonsense, the more obvious to an outsider.

        I hope I’m right that this is starting to play out now; I think it may be.

        Charles, can you say more about the violent incidents you mention? It’s concerning, and I haven’t heard about them so far. What happened?

      • TrueSceptic


        There are 2 recent posts at Deltoid about threats of violence, here and

      • Charles wrote:

        ,,,claiming frauds and conspiracy (between scientists, governments, and media) is an ultimate fallback position for some of these folks. The other fallback strategy,,,, is threatening or carrying out violence.

        The former by some is what makes the latter by others possible.

      • Thank you, TrueSceptic.

      • TrueSceptic

        And another. This seems to be happening a lot in Australia.

      • Painful.

        But better to know than not.

  17. Bern,

    Well, technically he’s got that covered by saying the iron core is small and the sun has a gaseous atmosphere. It’s not powered by fusion, by the way, there’s an “ongoing supernova” inside. I guess that’s not powered by fusion either.

    Plimer apparently got his ideas from a guy named Oliver Manuel, who–God help us all–actually has a Ph.D. in astrophysics. But like the late Tom van Flandern, he appears to have flipped out in his old age.

    • Oliver Manuel, the guy who has posted around the internet a lot (esp at Judith Curry’s blog) is a convicted sex offender (http://mominer.mst.edu/2006/08/30/dr-oliver-manuel-arrested-for-multiple-counts-of-rape-and-sodomy-of-his-children/ )

      Not much for ad hom’s, but keep in mind who you are dealing with, especially with these wingnut theories about the sun. But yes, the guy is one of the Tim Balls of the solar physics community

      • I’ve avoided posting that here, though it’s particularly galling that his crimes were against his own children.

        The Iron Sun crap’s whacko enough without the evil.

        Yet, it’s interesting that Watts has banned him, while Curry has not (despite his past being exposed there).

        So I guess that’s justification for outing him everywhere. The man has no moral compass, and indeed is a bit of a monster, yet Curry allows him to curry favor with Curry …

      • TrueSceptic

        I had no idea. I thought he was just a harmless nutter, ignored even by the other nutters, who keeps going on about how the Great Conspiracy Against Real Science started in the 1960s.

      • Recently I asked him questions about the predicted solar minimum, and he provided thoughtful answers.

      • Robert Murphy

        Was he actually convicted? The link says he was arrested for the charges, but I have not found anything that shows what the result of the trial was. I’d be very hesitant to call him convicted without providing evidence.

        [Response: The issue is rather sordid. And since the idea that the sun is primarily made of iron is too ridiculous to waste time on, I suggest we drop the whole thing.]

  18. There really is no excuse for this.

    Entering the term Volcanic CO2 into Google (Google.co.uk) gets a full page of results of which only one (WUWT) might contain the lie that human CO is less than volcanic. At the bottom of the page is Gerlach’s paper. This webpage is just blow Skeptical Science. The top link USGS states human CO2 is more than volcanic, while the second link (also USGS) doesn’t address the issue.

    But even without digging into the pages presented it’s clear – most of the sources on that Google page state that human CO2 dwarfs volcanic.

    Anyone who makes the claim that human emissions are dwarfed by volcanic CO2 is either stupid or a liar.

    So I’d suggest that the correct response to people claiming that is to provide a link to Gerlach and ask the question “Are you stupid or are you a liar?”

    I am heartily sick of the witless, smug, delusional, arrogant idiots that we so politely call deniers. But for netiquette I’d use a more direct term – Wankers!

    Sorry for the language and expression of ire Tamino, edit as you see fit.

    • “Anyone who makes the claim that human emissions are dwarfed by volcanic CO2 is either stupid or a liar.”

      Don’t neglect the possibility that some may be both!

      (Sorry, it’s been a bad day.)

      • It’s often hard to tell, but in this case it resolves to just stupid. If they are lying, they would also have to be idiots to expect anyone to believe such a ridiculous and obvious lie.

      • @TrueSceptic
        Or they are lying and know that there are enough idiots, who believe such a ridiculous and obvious lie.

      • In all fairness, there are also the misinformed – those who got their information on volcanic CO2 emissions from their regular information channel, which, sadly, is often something like Fox News…

    • Sometimes the (correct) claim is made that the emissions rate of some volcano greatly exceeds those of civilization. What they never mention is – that particular eruption phase only lasted 3 days.

      [Response: As Gerlach says in his article:

      The nearly 9-hour duration of both the Mount St. Helens and Pinatubo paroxysms gives average CO2 emission rates of about
      0.001 and 0.006 gigaton per hour, respectively. Intriguingly, the anthropogenic CO2 emission rate of 35 gigatons per year —- equivalent to 0.004 gigaton per hour — is similar. So, for a few hours during paroxysms, individual volcanoes may emit about as much or more CO2 than human activities. But volcanic paroxysms are ephemeral, while anthropogenic CO2 is emitted relentlessly from ubiquitous sources


      • You’re both on the same page (and hopefully you both recognize it …)

        Though Jay’s point is only correct for very very huge and rare eruptions (and I doubt he disagrees with that)

  19. Those who don’t buy ‘consensus’ views on volcanic CO2 can do a simple calulation.
    1. look up the CO2 concentration of morb (google scholar should get you close).
    calculate the annual volume of new oceanic crust produced (spreading rate times ridge length times 7 km.

    multiply the concentration by the volume.

    I may have done this in an old blog post. If not, I will write it up.

    The reverse calculation is even easier: Pinatup ejected about 10 billion metric tonnes of magma, so for that eruption to have contained 30 gigatonnes of CO2 (one year’s worth of emissions), the magma must have been 300% CO2.

  20. Ray Ladbury

    Also, as has been pointed out many times here–a volcanic eruption produces a large volume of rock, which takes CO2 out of the atmosphere as it weathers. I think that this makes the net contribution of volcanism to CO2 actually negative, does it not?

  21. Useful paper on volcanic forcing:
    A monthly and latitudinally varying volcanic forcing dataset in simulations of 20th century climate

    Click to access ammann.pdf

  22. Ray,

    I wouldn’t think so. Volcanoes adding more CO2 is an essential part of the carbonate-silicate cycle that keeps Earth habitable. See Berner and Lasaga or the many papers by James Kasting.

  23. If volcanoes did have the impact on atmospheric CO2 that could dwarf human emissions, you’d expect a much different pattern in the plots of atmospheric CO2 vs time. Instead of a steady increase, you’d get larger variations and “spikes” at peak volcanic activity, but if you look at a typical plot (say Mauna Loa’s time series) you can’t spot volcanic eruptions at all.

    • … which goes to show that Plimer has an extra orifice he talks from when burping with volcanoes. He’s deficient and wonder how he ever managed to get his degree, which is not one of any scientific note. Wonder if Tim Ball has ever had anything to say on this [he definitely needs McI ”impartial” auditing]

  24. Historical value:

    Ekholm, Nils, 1901. On the Variations of the Climate of the Geological and Historical Past and Their Causes. Quarterly Journal of the Royal Meteorological Society. vol. 27. Pgs. 1-61

  25. Starwatcher

    “Plimer is the guy who thinks the sun is made out of iron (Heaven and Earth, p. 120). ‘Nuff said.”

    ??? Even assuming the Sun was made of iron is true, how does that help deniers ??? Why is it this claim would appear in a book over Climate Change?

    • “Why is it this claim would appear in a book over Climate Change?”

      Why, indeed–and yet I’ve met a couple who were gaga about this. Or rather, this *too.*

      • i think the general train of thought is something like:

        * scientists say the sun isn’t iron.
        * actually it is.
        * trufact.
        * if they’re wrong about that, they’re also wrong about AGW.

      • I suppose. And then they start babbling something about “Galileo.”

  26. Michael Hillinger

    One thing I noticed on the Real Climate site is that the poster did not say that Volcanoes produce more CO2 than humans but that a single volcano just negated any carbon savings we have had via different mitigation strategies.

    That’s probably true, given we don’t seem to be reducing our carbon output.

    [Response: On the contrary, he said “When the volcano, Mt Pinatubo, erupted in the Philippines in 1991, it spewed out more greenhouse gases into the atmosphere than the entire human race had emitted in its entire YEARS on earth.”]

  27. Starwatcher, apparently it’s Plimer’s unique version of “it’s the sun doing it.”

  28. Michael, he did say this:

    Here’s an interesting fact. The volcanic eruption in Iceland, since its first spewing of volcanic ash has, in just FOUR DAYS, NEGATED EVERY SINGLE EFFORT humans have made in the past five years to control CO2 emissions on our planet.

    However, that doesn’t negate the fact that he also went on to say what Tamino has quoted.

    Sometimes it helps to read to the end of a post before suggesting that someone has misquoted it …

  29. Tapani, you may enjoy this excellent resource on climate papers, categorised by topic.


  30. And even if one little volcano in Iceland can negate five years of CO2 emission reduction efforts, then that tells a very clear story:
    We’re not doing enough to reduce CO2 emissions.
    But we already knew that…

    • Is there any reason to believe it did? I’m not taking the guy’s word for it.

      And in any case, to the degree that those mitigation efforts were structural, it’s comparing apples (a one-off event) to oranges (an ongoing change.)

      But of course, you’re right; we’re not doing enough to reduce emissions.

  31. The 2010 Eyjafjallajokull volcanic eruption emitted considerable CO2, but also halted a great many airline routes.


    Eyjafjallajokull emissions – 150,000 tons of CO2 estimated
    Airplane emissions curtailed because of ash risks – 344,109 tons

    CO2 reduction due to Eyjafjallajokull – 206,465

    Apparently, we need more ash-spewing volcanos…

  32. John Haythorn

    Check out this debate between Monbiot and Plimer. The volcano claim is a major part of it.


    [Response: As I’ve said before, no embedded video in comments please. I’d be delighted if you simply posted a link — it’s a good video.]

    • John, if you just paste in the website address for the YouTube video it will automatically get embedded as a video. However, if you do the html code for the hyperlink then it will be fine.

      I believe this is what you were talking about…

      George Monbiot debates Ian Plimer part 1, 2, 3

      Not particularly happy with Monbiot throwing Phil Jones under the bus here, but he does a pretty good job with Plimer.

  33. KR: your wish is fulfilled. The Puyehue Eruption has been going on since June 5th. The ash plume has lapped the planet twice an has shut down air travel in South America, Australia an New Zealand. I imagine that that may have a significant impact on global temperature.

  34. Craig Allen wrote:

    I imagine that [the 2011 Puyehue-Cordón Caulle eruption] may have a significant impact on global temperature.

    Not likely. Pinatubo was VEI 6 at 15 ° N latitude. This is VEI 3 and going down, and the latitude is 40 ° S.

    Being further away from the equator it will have less of an effect. But more importantly VEI is logarithmic base 10, so this is perhaps 1/1000 a Pinatubo. Maximum effect of Pinatubo was I believe a reduction in temperature by 0.3 °C.

  35. “I imagine that that may have a significant impact on global temperature.”

    Craig, it takes more to impact global temperature than you may realise. A volcano like Puyehue struggles because it’s a) temporary, b) regional (despite lapping the southern hemisphere) and c) not all that big.

    While the eruption column and ash cloud may look spectactular, compare Puyehue (http://michkos.com/wp-content/uploads/2011/06/Puyehue-cloud.jpg) with Pinatubo (http://pubs.usgs.gov/fs/1997/fs113-97/resources/AshCloud.jpg). Yes there’s plenty of problems with eyeballing, but just look at the damn thing would ya? Pinatubo was pretty epic.

  36. Craig Allen wrote: “I imagine that that may have a significant impact on global temperature.”

    Nope, not very much at all, really. To significantly impact global temperature 1) the lighter reflective sulfate aerosols need to get into the stratosphere where they will not be rapidly rained out, and 2) the volcano needs to be close to the equator so that those aerosols will diffuse into both hemispheres.

    A VEI3 is just not big enough to eject significant amounts of sulfates into the stratosphere, and 40 ° S is just too far from the equator.

  37. Holly Stick

    My favourite website for news about volcanoes also has a new post about the Gerlach article: http://bigthink.com/ideas/38998

  38. Ian Forrester

    Another good site for volcanoes is :


    It lists all VEI 4 or greater eruptions for the past 12,000 years.

  39. Actually, the impact of ash-spewing volcanoes (as I posted earlier, 6/21) is to reduce CO2 levels by shutting down air travel.

  40. Some interesting and commentary and rather devastating critique at DD: http://denialdepot.blogspot.com/2011/06/co2-volcanoes-or-man-its-your-choice.html

    • Igor Samoylenko


      “No longer must we suffer years of “education” and be forced to bow down before peer appointed so-called “experts” as they cast down facts upon our heads”

  41. Igor, you laugh, but I actually know people who think this way. When people find out that I am a physicist, I’ve actually had them give me a dog-eared manuscript with a title like “Einstein Was Wrong, Wrong, Wrong!!!”. Generally, the kook factor correlates strongly to the number of exclamation points used. When I point out that there are no equations, they will say that they don’t need math to understand the obvious and usually imply that I have been “brainwashed by my education”.

    [Response: You bring back memories… Most are just loony, but I’ve seen some that are actually *scary* because their “work” suggests mental imbalance combined with extreme anger.]

    Stupid is that natural state of man. It is only by education and science that we ever come close to transcending it.

  42. Ray Ladbury wrote:

    Generally, the kook factor correlates strongly to the number of exclamation points used.

    Certain clues in how people write can be rather telling. Something I will always notice is the systematic failure to capitalize the beginnings of sentences and the word “i”. That is almost inevitably indicative of someone who debates with no concern for the truth. They will simply be out to score points no matter how dishonestly they have to argue (e.g., misrepresent their “opponent’s” argument) in order to do so.


  44. i agree.

    couldn’t resist. Well, okay, I could have, but unfortunately I didn’t. Interesting times. Surprise, surprise, surprise, Gomer Pyle is now a blog scientist. Shazam and golly!

  45. Ray Ladbury

    Oh yeah, at my old worksite–the building said “Physic” on it–they used to call me down to the lobby to deal with these guys. We got a couple of homeless guys who were quite obviously tuned to a different station–some to multiple stations at once.

    Then there was the lawyer who accused me of being a stooge and a spy and a lot of other things in a 20 minute phone conversation. He called back a couple of days later and apologized, saying, “I was in my manic phase…”

    I’ve also been threatened by a few loons on the Intertoobz. Most of those guys would be too dim to see anything through in any case, though.

  46. Ray Ladbury wrote:

    Then there was the lawyer who accused me of being a stooge and a spy and a lot of other things in a 20 minute phone conversation. He called back a couple of days later and apologized, saying, “I was in my manic phase…”

    Might have been the beginnings of mixed mania. A lot of bipolars think they are more creative and productive when they are bipolar. I had one friend state that the experience was comparable to taking cocaine.

    My wife has a friend where creativity, driven by that excited state, gradually gave way to incoherent thinking as she increasingly became distracted by any stray thought, that at the moment seemed like the most important thing in the world. In time her episodes would result in furious bouts of writing where, upon entering a more normal state, she would examine what she had written and she could not make heads or tails of what she had written, even at the level of individual sentences.

    Bipolars also tend to be perfectionists. And many go into medicine. I knew a surgeon in training that avoided taking the medicine because she thought she was more productive with the mania and was willing to pay the price of depression when that hit for the sake of it. So if you are being operated on and you look up into your surgeon’s eyes and see someone looking down at you with intensity, apparently excited, really enjoying what they can do with that knife, you will know why.

    But untreated long enough you get a nasty mix. The destructive impulses of someone who is depressed — which is usually rendered inert by lack of energy and even the feeling, “Yes, I could end it all, but what’s point,” combined with the energy of mania. Potentially a lethal combo for you and anyone around you when you go.

    And eventually, assuming you live long enough? A psychosis similar to that of untreated, extreme schizophrenia. Brain scans have revealed that many of the same centers are especially active during both forms of psychosis. Likewise many of the same genes seem to be involved.

    Anyway, I knew an undersea photographer. Quite charming, entertaining people from around the neighborhood that he didn’t even know in his back yard, grilling hamburgers, hot dogs, serving soda and wine. But he refused to take his medicine, and with mixed mania a paranoia took over that made him a danger to his own family. His wife had to take out a restraining order.

    But avoiding the long-term effects of untreated bipolar or even the depths of bipolar depression aren’t the only reasons for taking your medicine. Nor for that matter the manner in which mania loses its tethers and floats off into the feeling and even the sense that you are the Kwisatz Haderach. There is also a chronic low grade depression that forms the background of your everyday life when you aren’t in the throws of either of the two extremes of the condition.

    Which reminded me while I was writing this. I was feeling a little angry but at nothing in particular. And it was getting worse as time went on. Then I realized that I had forgotten to take my medicine earlier today. But I took it while waiting for the bus, and like Harry’s father in Night Court I am feeling much better now.

  47. Timothy,
    Well, in the physics community, one need only look to the example of Schrieffer, and I lost a good friend a few years ago to suicide after she lost a battle with her bipolar disease. My friend and I were grad students togethere on the same experiment. After she graduated, her behavior became more and more erratic, and she couldn’t sleep. I saw her a lot as I was writing my thesis late into the night–I didn’t have time to sleep…she couldn’t. She had a setback in her career when she ran into a sexist pig at a national lab–and then into the sexism of the lab culture itself–and never quite recovered from that.

    In my time as a physicist, I’ve dealt with lots of narcissists, a fair number of bipolars and a few Borderlines. I’ve always said Abnormal Psych was the best physics class I ever took.

  48. It doesn’t surprise me that she had a career in physics. There are certain career choices that people with different psychological conditions will gravitate towards. Bipolars tend to gravitate to positions where they can help people. As I said, doctors are more likely to be bipolar. Both the lady surgeon in training I knew and my heart surgeon. They are also more likely to be programmers. Gives them a chance to use their creativity, perfectionism and more generally their minds.

    But oddly enough people with Aspergers are also more likely to go into programming, as it lets them direct all their focus on one problem and involves less contact with others who they have difficulty interacting with and find generally distracting. I had a boss who seemed to have Aspergers and was like that. They also tend to go into engineering.

    However, one of the most personable people I ever knew had Aspergers. But I knew him only online where on the other end he would work and worry over his contributions to an email list prior to sending them in, knowing his natural tendencies, and by act of will and intellect overcoming them.

    Then I knew a schizophrenic who was on her medicine and she was a night guard at a construction site. On the medicine she would still hear the voices but they were fainter and she didn’t have to focus on them. And as a night guard she was able to avoid contact with other people. Even on the bus she preferred to avoid contact with other people, but for the most part seemed fairly normal.

    But yes, bipolars tend to have difficulty sleeping, at least when they are manic or simply hypomanic. When I first really became aware that something was wrong I would be extremely excited in the morning, feeling like I was on top of the world, that thought was effortless, insight instantaneous and unquestionably certain, and like there was nothing I couldn’t understand. But then I would hit a wall of anxiety at 11:00 AM and be ready to climb into a crack in the floor for the rest of the day. Until 11:00 PM. Then I would start to climb back into mania.

    Then I would sleep for only three hours. I couldn’t sleep any more than that. Brain chemistry, and the circadian rhythm which can be driven by a simple chemical clock that is sensitive to cues in its environment. Day after day, more than two weeks straight. The clockwork behavior of rapid cycling. Other symptoms, depending upon the episode would include vivid colors, extreme sensitivity to sound and light, and more intense entity-background phenomena where the perception of the entity as standing out from its background was stronger.

    And emotions could be far more intense. Like they were on loud speakers. Perhaps the effect of heightened introception, perception directed inwards. I suspect this was part of what drove the feeling of excitement, extreme confidence and certainty, particularly with respect to whatever “insights” one had into people’s psychology or anything else one turned one’s fleeting attention to. But in the state of extreme depression it would also drive the extreme self-doubt and even shame.

    Bipolar and schizophrenia are the two conditions in which the sufferer is less likely to take their medicine. With schizophrenia its due to the paranoia. With bipolar it is due to their not wanting to give up the mania with its excitement, creativity and productivity. But both conditions become worse over time if left untreated. Your friend has my sympathy, both for what appears to have untreated bipolar and for suffering the sexism.

  49. I have several coworkers with conservative Christian beliefs that lead them to deny generally accepted theories (evolution, AGW, even GW/CC) that contradict their understanding of what scripture says. (“The Earth IS about 6,000 years old”, I was told by by biologist-trained supervisor.) They don’t actively preach AGW is false, but if asked, one says “It’s natural cycles” (without further explanation) and another says “Don’t let upstairs folks hear that we’re wasting our time on this stuff.” These folks are effective at their work (supervisors, engineering, IT, finance). I doubt they look at any GW or anti-GW blogs, so they are not the ones we meet occasionally (all too frequently) on blogs such as this. I’d hazard to guess that folks like these coworkers make up the ~20-30% of the US population that sees a lot of things through amazingly distorted glasses. I suspect they will die believing humans didn’t cause the climate change we’re experiencing.

  50. Ian Forrester

    Barry Cooper, University of Calgary Political Anti-science professor, had the following piece of fetid garbage in yesterday’s Calgary Herald:

    Volcanoes matter. Somebody calculated that in four days, the Grimsvotn eruption in Iceland a month ago wiped out five years of effort to control CO2 emissions. No one has required Iceland to purchase carbon offsets. Yet.

    Somebody else calculated the year-long eruption of Mount Pinatubo in the Philippines 20 years ago spewed more carbon dioxide than the entire human race for the whole of human history.

    Barry Cooper is a friend of the Friends of Science and has been actively involved in climate science disinformation for many years.

    You can read his full article here:


  51. Once I initially commented I clicked the -Notify me when new comments are added- checkbox and now each time a comment is added I get four emails with the same comment. Is there any way you can take away me from that service? Thanks!

    [Response: I’m afraid I don’t know how. Does anybody here know? Is there an “unsubscribe” link in the emails? If you don’t get an answer soon, let me know and I’ll try to contact wordpress to find out.]

    • Tamino, not sure this is a “real” comment.
      I searched for the first seven words, and found this exact same comment (and some with a slight difference) many, many, many different places.

      Looks like some kind of spambot.

    • The original subscribe / confirmation email leads to a page listing all associated to a handle/email address. There you can untick. Also the Notify emails have an ”unsubsribe link” which allows a quick way out for just the related topic.

      (probably answer #4 ;-)

  52. AvgAmerican44yoMale

    I would like to ask a question on your blog as a guest if I may. (I apologize in advance if this is a private forum, please delete my post if it is.) I wouldn’t be here on this post if I hadn’t recieved a junk email that I decided to verify or trash once and for all. I am not a climate change skeptic or a climate change believer. I have a a slightly above average education in science. The subject of this blog is to shed light on the claims of many that volcanoes emit far less CO2 then others claim they do. That volcanoes emit far less CO2 than humans do. Therefore humans cause the majority of the CO2 emmissions. Therefore humans are causing climate change. Using the words from one of the original posts on this blog, named Icarus: “This is clearly true from the fact that atmospheric CO2 was stable at 280 ± 5ppm for all of the last 10,000 years up to the start of the industrial revolution. Only anthropogenic emissions have been causing a net increase in atmospheric CO2.” I have no problem believeing these posts and won’t allow myself to be swayed by the occasional junkmail that proclaims the opposite to be true. I am not trying to be smart aleck here, just trying to get a simple question asked and hopefully answered. I would appreciate if I am not talked down to, but I can certainly understand if you delete my post (after answering of course). If the CO2 levels have remained constant, for the last 10,000 years, only to be recorded higher since the industrial revolution, and there is reasonable evidence of numerous (often quite radical) climate changes to the Earth in that 10,000 years,

    [Response: I’ll just get things started, and let others correct other misconceptions in their own comments.

    This is not true. There is not evidence of radical climate changes over the last 10,000 years — nothing nearly as big as we expect to happen in the next 100 years. In fact, the climate *stability* of the Holocene has been very favorable for the flourishing of civilization.]

    then how or why has the CO2 level even been connected to climate change. In another, simple way of stating it, the previous evidence of climate changes was obviously not caused by shifts in the CO2 levels, since they ‘remained constant’ why is it being assumed that CO2 levels are causing the current climate change? My opinion is that connecting CO2 levels, caused by humans, to climate change, is every bit as radical as Ian Plimer claiming the volcanoes release an amount of CO2 that obviously has been proven untrue. Not to mention stating the sun is made of iron, which even my science background can calculate is untrue. If you could explain this in a scientific manner perhaps it would go a long way to help a lot of average Americans understand why humans are the cause of the current climate change and why CO2 releases need to be controlled, even if it is at a large cost. Thank you for your time. I look forward to reading your replies.

    • Daniel Bailey

      Might I suggest running over to Skeptical Science and reading the following links as a start:
      Newcomers, Start Here
      The Big Picture

      What you have asked here has already been done there, in exquisite detail. If you have any questions about what you read there, post those questions on the most appropriate comment threads (many thousands exist) and one of the many learned participants there will get back to you.

      Or I will. :)

    • Tamino’s right that we’ve actually experienced a pretty stable climate over the past 10,000 years — at least compared to the previous 10,000 years, or to the probable course of the next 200 years.

      Aside from that, we don’t say “CO2 causes warming” just because CO2 happens to be rising at the same time that the planet happens to be warming. We say “CO2 causes warming” because basic physical principles suggest that it should do so. The fact that CO2 is rising now, and the planet is also warming, fits nicely with that physical theory, but it’s not the *reason* for that theory.

      The fact that climate changed in the past, for reasons other than CO2, doesn’t mean that the climate won’t *also* change if we tamper with CO2. Many fires are started by natural causes (lightning) but that doesn’t mean that no fires are caused by arson. In fact, until the appearance of humans, *all* forest fires on the planet were “natural”, just like all climate variations were “natural”. But people can start forest fires, and people can alter the climate.

      Finally, it’s difficult to study the distant past, but geologists are pretty clear that there are previous episodes in Earth’s history when natural increases in CO2 led to warming of the planet (for example, during large flood-basalt episodes, when large-scale volcanism greatly increased the CO2 concentration of the atmosphere and the Earth responded by warming).

  53. AvgAmerican/
    Here is a graph that shows just how stable the past 10,000 years have been temperature wise (samples from Greenland).

    A brief description of what caused climate changes in the past is given here.

  54. Kevin Stanley

    Well, I think Tamino’s point that there haven’t been such dramatic shifts in the last 10,000 years pretty much takes care of the argument. But I would go on to add that other climate changes in the more distant past have been linked to CO2; not as the initial forcing that got the ball rolling in most cases, but as a feedback…one that is necessary to explain the changes. Without factoring in CO2’s greenhouse properties, many past climate changes don’t make any sense.

  55. Ray Ladbury

    First, it is not mere correlation that is the basis for attribution. We have known for 160 years that CO2 is a greenhouse gas, and that greenhouse gasses warm the planet. That anthropogenic CO2 would warm the planet was first predicted in 1896!

    To understand why we are so certain CO2 is behind the current warming, you have to understand a little bit about how greenhouse gasses work. The Sun is the source of virtually all Earth’s energy. Without Solar radiation, Earth would be at the same temperature as space–2.7 degrees C above absolute zero.

    Visible light from the Sun passes through the planet’s atmosphere and warms the planet. When any body is warmed above absolute zero, it will radiate with a spectrum that is determined by its temperature (and MOSTLY independent of its composition). For Earth, most of that radiated energy is in the infrared. So Earth’s energy budget consists of visible light coming in and infrared going out. If the energy doesn’t get radiated away as infrared, it doesn’t leave Earth. Clear?

    What greenhouse gasses do is absorb some of that infrared energy before it leaves the atmosphere. This energy causes the molecule to vibrate. And more often than not, the vibrating molecule will collide with another gas molecule (mostly Nitrogen or oxygen) and give up this energy before it radiates it away as an infrared photon. So, greenhouse gas molecules take outgoing IR and turn it into molecular motion–which is temperature. Still clear?

    This works when temperatures are higher down below and higher up above–that is when you have more IR photons coming from below. This is the case in Earth’s troposphere. In the stratosphere, temperature rises with height. Here, collisions get turned into IR photons and radiated, so we expect the stratosphere to cool due to the greenhouse effect. And in fact that is just what we see. The greenhouse effect is the only effect we know of that explains BOTH tropospheric warming AND stratospheric cooling!

    We also have loads of evidence from Earth’s distant past–whenever you get more CO2 the climate is warmer than it would be otherwise.

    So why are scientists concerned? Well, as Tamino pointed out, the planet’s climate has been exceptionally stable over the past 10000 years, and that period is precisely the period when all the infrastructure of human civilization has been produced–all our crops, domestic animals, transport, etc. We depend on that stability for everything–especially as Earth’s population nears its crest of ~10 billion people. I would recommend taking some time to look over http://www.skepticalscience.com. You will find lots and lots more evidence there.

    Finally, you have to understand that scientists are pretty smart. They don’t just start believing things for no reason. They require hard evidence. The fact that they have established more than 90% confidence that we are warming the planet means you can take it to the bank.

  56. My opinion is that connecting CO2 levels, caused by humans, to climate change, is every bit as radical as Ian Plimer claiming the volcanoes release an amount of CO2 that obviously has been proven untrue.

    Not similar at all. We know that CO2 is a greenhouse gas via observations in the laboratory, for starters. We know that basic radiative transfer theory is sound because of observations of back-radiation (see this: http://scienceofdoom.com/2010/07/17/the-amazing-case-of-back-radiation/) , satellite observations of energy radiated from the atmosphere, etc.

    So to debunk climate science you have to, among other things, show that these observations are somehow false. And I’m not even scratching the surface, here. Debunking of climate science would require that huge chunks of physics etc be tossed into the trash. And people would have to stop using CO2 lasers, too, because such an extensive debunking of modern physics would cause them to stop working …

    Plimer’s claim, on the other hand, is *refuted* by scientific observations.

    So rather than the two claims being “equally radical”, the two are as opposite as can be.

  57. Didactylos

    Luckily, we have a longer record than just 10,000 years. Our longest CO2 records go back hundreds of thousands of years, and this allows us to see the link between CO2 and temperature very clearly.

    Yes, CO2 levels and temperature have been relatively constant during the last 10 thousand years (the Holocene), but earlier than that we had a series of ice ages that correspond neatly with CO2 levels.

    The link is so clear it is beyond doubt*.

    Exactly how the link works is a little more involved. Please ask if you want more details. If you only want the Cliff notes, then it is enough just to know that the radiative properties of CO2 that cause the greenhouse effect were calculated over a hundred years ago. Modern experiments show that they got things surprisingly close, considering how long ago it was.

    * Reasonable doubt, obviously. There are a lot of unreasonable people out there….

  58. Avg, there’s a lot of “if” stuff in your questions, you need to sort out the various assumptions first.

    For climate variation, try this:

    For “even if it is at a large cost” ask your grandchildren whether they think you should be spending your money now to keep the climate during their lifetime comfortable.

  59. Oh, and you can use Google to find out actual numbers. For example:
    “… let’s break down the costs of climate mitigation:
    For the US, 2 percent of GDP equals $288 billion. Per person, that works out to about $938 yearly. It’s not exactly nothing. But it’s also not overwhelming. On a monthly basis — $78 per month — it’s a little higher the price of the average cellphone plan….”

    Yes, you can find people saying it will cost you an arm, a leg, and a kidney right now and they’ll come take it out of your hide. But don’t believe everything you hear from people. Think. Ask a librarian about these questions — you’ll get help looking up good information and deciding for yourself, from a professional who knows how to find facts for people.

  60. Philippe Chantreau

    AA44YOM, try this site for lots of good information on basics, use the search engine function:

  61. My opinion is that connecting CO2 levels, caused by humans, to climate change, is every bit as radical as Ian Plimer claiming the volcanoes release an amount of CO2 that obviously has been proven untrue.

    OK, I’ll bite, even though I’ve been hooked by many a faux-reasonable troll before.

    The difference is that Plimer’s assertions are trivially easy to refute, whereas the sudden excursion in CO2 concentration is robustly attributable to human influences, and the consequent effects are predicted by discoveries in atmospheric physics going back at least to the 19th century.

    Taking your comment at face value, I would say you seem well behind the knowledge curve on the subject. If you are sincerely curious–a proposition I find dubious based on my prior experience–I recommend you start filling in the blanks here:

    I hope you will prove me wrong about your sincerity. It would be nice, for a change, to encounter a genuine skeptic seeking knowledge.

    • AvgAmerican44yoMale

      Hones to God, I am not a troll. I just don’t work in the field. I am getting quite tired of all the ‘Experts’ giving their opinions because it is quite obvious they are not in the field either. Believe it or not I am a computer programmer in a scientific type environment. I promise you all answers stay here, that’s why I offerred to let you delete my comment.

  62. AvgAmerican44yoMale,

    It’s not a matter of assuming CO2 is causing the present warming. It has to from what we know of radiation physics. If you put more CO2 in a planet’s atmosphere, then, other causes aside, it has to get warmer. For some more information, try here:



    These two and many other pages on the general subject can be found at:


  63. AA44yoM
    There’s a nice graphic for the volcano/human comparison here.
    http://www.skepticalscience.com/volcanoes-and-global-warming.htm And the Intermediate version of this item gives a different graphic comparing volcanic eruptions to accumulated CO2 concentrations.

    As for “radical” climate changes, they’re all millions of years ago. The PETM was a mere 56 million years ago, whereas the ‘snowball earth’ was hundreds of millions of years ago.

    • AvgAmerican44yoMale

      Maybe my word ‘radical’ was wrong in this environment, but I was referring specifically to the Medieval Warming period (900-1300 AD, where it was warmer than today, at least in the Northern Hemisphere)

      [Response: No. It was not. Whoever told you that was either stunningly ignorant, or an outright liar. Where did you get that misinformation?]

      and the following cooling period (1400-1850 AD).

      [Response: But the temperature change from medieval warmth to “little ice age” was almost certainly less than we have *already* seen in the 20th century — and *far* less than we will see in the 21st century.]

      Maybe it was incorrect to use that word, radical to describe these periods, but my point was that there IS climate change, both hotter and cooler, that obvious wasn’t caused by the Industrial Age and massive CO2 levels.

      [Response: So what? Some forest fires are caused by lightning — does that mean it’s impossible to start one by arson? That’s just illogical.]

      But I am reading through all these posts, it will just take a day or 2, I have to work also.

      [Response: It’s now clear why you have some of the opinions you do. You have been seriously misinformed about climate variations in the past. You need to start being skeptical about both the scientific knowledge, and the honesty, of the people who told you those things.]

  64. “In another, simple way of stating it, the previous evidence of climate changes was obviously not caused by shifts in the CO2 levels, since they ‘remained constant’ why is it being assumed that CO2 levels are causing the current climate change?”

    Nothing is being assumed. Here’s a list of things we know, not assume:

    – Carbon dioxide is a greenhouse gas. This means that it absorbs longwave radiation emitted by the Earth and the atmosphere, and it also re-radiates longwave radiation in all directions.
    – Adding greenhouse gases to the atmosphere warms the planet up. There are various ways of looking at this, from the simple “energy is trapped” to the more complex “energy that would have escaped to space is redirected to the surface”, even “the effective radiating level of the atmosphere is forced to a higher altitude, warming the surface via the lapse rate”.
    – The amount of longwave radiation emitted to space across the whole spectrum is monitored by satellites, and the observed changes are consistent with what we expect, given CO2’s absorption characteristics.
    – If the amount of CO2 is doubled, then the so-called radiative forcing – the difference in net radiation at the top of the troposphere – is around 4 watts per square metre.

    These facts establish that adding CO2 means that the planet will warm up, leaving us with the question, ‘by how much?’.

    – We can establish from some not too complex equations that, if we consider the effect of CO2 alone, that 4 W/m2 difference equates to an equilibrium warming of approximately 1C, averaged over the whole planet, with only a small margin of error..

    This is where assumption-free facts must come to an end, because the full effect comes down to feedbacks and these necessitate assumptions, and the inherent uncertainties result in the oft quoted temp rise of 2 – 4.5C for a doubling of CO2, commonly called ‘climate sensitivity’.

    Finally, it is not the case that just becuase CO2 didn’t cause (or only played a minor part in) climate chance in the holocene, it can’t cause climate change full stop. Say I broke my leg falling out of a tree; does that mean that all broken legs are caused by tree falls, and I don’t need to look both ways before crossing the street?

  65. john byatt

    Spencer Weart’s History of Carbon Dioxide Greenhouse Effect is worth reading ,most of the sceptic arguments now refer to sensitivity rather than refuting human cause of increased atmospheric levels of CO2 and warming


  66. AvgAmerican,

    You don’t need to apologize for asking questions. If people get frustrated at legitimate questions, it’s probably only because of the amount of “questions” phrased in an authoritative, accusatory, and conspiracy-type fashion that we deal with all the time; I’m sorry if the legitimately curious, such as yourself, suffer from this.

    There’s some interesting variability and evolution over the last 10,000 years (which we call the Holocene). Some notable examples include much different behavior in the monsoons over the Holocene, and in fact there are many different regional responses between the major monsoon systems around the world (in the America’s, Africa, Australia, and Asia)

    There are also changes in the position of the Intertropical Convergence Zone over the Holocene (this is a globally encircling convective cloud/precip band that is positioned near the equator). These responses generally evolve as a function of orbital forcing, but there’s some interesting issues early in the Holocene (for instance, something called the 8.2k event, that may have been triggered by ocean dynamics in response to a local forcing)

    Some of the more “popular” climate anomalies of the last millennium are the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA), which have large regional climatic (and social) impacts. As Tamino pointed out in his response to you though, these are still relatively small when placed in the context of the temperature change we expect to see from a doubling or tripling of CO2, or the transition between ice ages, etc.

    The point here about volcanoes is not to serve as a proof that CO2 (natural or human) causes climate change– it’s just to point out we release more CO2 than a volcano does, nothing more, nothing less.

    The evidence that CO2 causes climate change does come in part from Earth’s history, but actually it’s primarily simple physics that can be figured out whether or not we have any climate data of the past at all (some of the earliest calculations of how CO2 changes things were done when global temperature and CO2 data weren’t even around yet, for example in Arrhenius’ 1896 paper). When you add CO2 to the atmosphere and keep its temperature constant, you force the Earth to lose heat energy less efficiently. It must eventually increase its temperature to come back into a radiative equilibrium state. That’s pretty easy to work out.

  67. I’m having troubles understanding the question. It seems to me to be:

    If there have been times when climate changed by some other forcing than changes in CO2 levels, how can it be possible for changes in CO2 levels to effect climate change?

    Doesn’t the question answer itself? There are multiple agents of climate change. CO2 is one of them. When its levels don’t change, it’s not one of the forcings. When its levels do change, it is.

    BTW, I think your understanding of the history of the discovery of CO2’s nature as a greenhouse gas might be backwards. Try reading: http://www.aip.org/history/climate/index.htm Connecting changes in CO2 to climate changes isn’t an assumption. It’s based on the known physical properties of the gas.

  68. I think our troller has filled his creel :)

  69. I think our troller has filled his creel :)

    Aw, c’mon D: let me dream a while! Surely there is one sincere skeptic out there. Maybe this is him!

    **sigh** OK, no, I suppose not. I should know better by now.

    • AvgAmerican44yoMale

      I am a sincere skeptic. I appreciate all the answers above. I have quite a lot to read now with your answers and the links. By the way, I am not a troll. Don’t have time for that kind of nonsense…
      Thanks again. Give me a day or two and maybe I will increase the complexity of my questions.

  70. And even if it *was* a troll, I thought the responses on here were very polite and well put. Anyone finding the ‘troll’ question will find an abundance of well-reasoned, scientifically based answers directly after it, that both point out the erroneous assumptions in the question, and set out just why we think CO2 is an issue. The links to some of the good explanatory pages out there are just a bonus.

  71. Ray Ladbury

    Sincere questions are always welcome. Understand that we get a lot of questions that aren’t sincere, though–and a lot of them come from programmers. There are a lot of people out there who think they understand science, but are just flat wrong.

    • Horatio Algeranon

      In Horatio’s experience*, the only folks more arrogant than the physicists (as a group) are the computer programmers — or “software engineers” as the elite among them like to call themselves, though in actuality, what most of them do has little in common with real engineering — or with reality, for that matter.

      The physicists actually have a legitimate reason for being arrogant when it comes to understanding the real world.

      Many programmers don’t even inhabit the real world governed by physical laws. Instead they inhabit a virtual reality where literally anything goes. (It’s actually kind of funny that some of these people criticize scientists for their simplified models, which at least make an attempt to take physical laws into account.)

      And any two year old can learn a language (human or machine).

      *Horatio has experience with both groups, having a bachelors in physics and having spent more time than he’d care to think about employed as a programmer (the official title being “software engineer”, of course).

      • Andrew Dodds

        Yes, I’ve a science background but program computers for money..

        There is a big difference in mindset between Software engineer and Scientist – it’s a case of ‘What’s the best (latest/most general/etc) way to implement the solution to problem X’ – where the solution is generally known beforehand in the form of requirements – vs ‘How do we solve problem X using a computer’.

        Both approaches have strengths and weaknesses. Software engineers can end up writing beautifully crafted code that doesn’t do anything useful, because the code crafting took precedence of the problem at hand, and scientists-programming-computers can end up solving a problem correctly, but in the process leaving code that can never be comprehended by any human, ever.

  72. AvgAmerican, I had a feeling you were referring to the Mediaeval Warm Period in your original question… I’m a non-scientist too, and I’ve been lurking in various science blogs (and a few contrarian ones) for some years now. The MWP was one of the issues that caught my attention early on. I think the skeptic reasoning goes like this: ‘There were natural factors at play back then which caused the climate to warm by a degree or two for hundreds of years. No one seems to be able to explain those natural factors accurately, so who is to say the same mysterious forcings aren’t messing with the climate now?’
    To take this complaint seriously, however, you have to first explain why the physics of greenhouse gases is all wrong and the numerous observable ‘fingerprints’ of greenhouse warming are malarkey (see various lucid posts above). Then you need to identify the physical mechanisms that ARE in play, the ones that fuelled the MWP, and that are now so carefully mimicking the predicted effects of the rise in CO2 concentrations. Has anyone been able to do that? No.
    It would be neater if the paleoclimate teams could explain exactly what was going on a thousand years ago, but we can’t know everthing, instantly. Best guesses involve stalling of ocean current oscillations and shifting wind patterns – people are looking into these. Skeptical Science has an update here. (And of course, it wasn’t as warm as some would have you believe, nor as planetary.)
    Another issue that I wondered about early in my lurking was the sheer size of the natural carbon cycle, and the rather smaller human CO2 contribution to it. But that’s another issue, and involves stories about water running into leaky bathtubs. :)

  73. Horatio, as a physicist, I must take issue with your post. Physicists are every bit as arrogant as programmers, and not all of us have any real reason to be so.

    • Horatio Algeranon


      You may be right. Horatio’s personal experience might not be a representative sample.

      Prolly best to say both are arrogant and not try to decide who is more arrogant, which might really might amount to quibbling about the difference between a 9.9 and 10.0 on the Pomposity Scale, ar any rate.

      It might be difficult to nail down just who is actually more arrogant — the physicsts or the programmers –, especially since some physicists are also programmers (and it might be hard to sort out which ego dominates.)

      And Horatio certainly did not mean to imply that all physicists have a reason to be arrogant, only that when it comes to modeling the real world, physicists as a group have a fairly good track record.

      The real problem is that some believe that because they understand physics and/or programming, they understand everything there is to know (about everything.)

  74. Well, our boy AA44yoM has sworn sincerity. That’s promising.

    OTOH, he’s an engineer. Very ominous.

    What will he post next? More standard denier tropes from the usual sources, or genuine questions based on what he’s learned?

    C’mon, AA, don’t let us down.

    [Response: I suggest we be less hostile. There really are people who are just beginning to learn some of the science.

    This is made far more difficult because there’s such a vast amount of well-crafted misinformation on the internet — the “fake skeptics” are amazingly good at making fools of people. To see through the deceit takes very sharp critical thinking skills, and a heckuva lot of good information simply because there’s such a mountain of hogwash.

    Seeing through the veil isn’t easy. Let’s not chastise those who are having a hard time doing so, instead let’s make it easier for them.]

  75. Have to agree with tamino. It’s always easier to strike out than to be helpful, but the latter is more ethical. If the person proves to be a troll, then we can kick him in the nuts (or nuttesses).

  76. Heck, I thought I was being encouraging!

    Am I getting hopelessly cynical? Perhaps I’ve been doing this too long.

    Anyhow, here’s a new post at SkS that our skeptic might find enlightening:


  77. “. . . . nuts (or nuttesses).”

    I knew this comment thread had gone too long without mention of “The Best Science Blog On The Internet”. . .

  78. AvgAmerican44yoMale

    I’m still digesting the links. I have to work also so its hard to sit down and read through everything in one day. A lot of people posted shots/information and so forth above, so I will just compile all my answers into one post.
    1) Not a troll, but even if I was, its still good that you all would take the time to answer, you never know who else reads this. Have SOME faith in your fellow man.
    As I said, just tired of hearing the constant arguing back and forth between ‘experts’ when the ‘experts’ are usually far from it. Its always best to go to the source and see the information rather than get it second hand. Thanks again for the links.

    2) I am not an ‘engineer’. I am a computer programmer. And I don’t use ‘software engineer’ as my title either. As one of you said “Many programmers don’t even inhabit the real world governed by physical laws” I agree, most don’t even inhabit the real world. I however, in my job, must follow the rules of Physics. (I program for systems that rely on Physics) But the Physics are usually decided by the higher ups hence its not my job to argue them, just translate them to code.
    3) Somebody was rather irrited that I was informed that there was a Midieval Warm period also (as opposed to the Medieval Cool period). Asked where I heard that. Have heard it numerous places, but the easiest place to find it is a show that was on the History Channel, I think it was called ‘The Little Ice Age’ or something like that. Anyway, in order to explain the mini ice age, they start with 15 minutes of explaining the previous warm period. States pretty plainly that the Northen Hemisphere was quite warmer than today. Don’t know if they are right, just giving you a source of information/misinformation.

    I will respond with better questions once I have a chanc eto go through all the links that have been posted. Only gotten to a few so far. Thanks

    [Response: There was a medieval warm period, at least according to credible reconstructions of past temperature. There was also a “little ice age.” But the MWP wasn’t as warm as today, really not even close, again according to credible reconstructions of past temperature. It may have been in some very limited regions, but not globally or hemispherically. However, it has been claimed to be so because some powerful forces want to discredit the idea that we might be heading toward dangerous warming. A good idea of what the science says is conveyed by this graph, which shows the results of several credible reconstructions of past temperature:

    Please forgive the accusations of “troll,” and bear in mind that we get a lot of trolls and people tend to be very irritated by them. I believe you’re not one of those, and that it’s our duty to respond with good information, not insults.

    Also bear in mind that there is a lot of misinformation about global warming. Some of it really is brilliantly crafted, and it’s specifically designed to create as much doubt as possible, both about things on which there really is doubt (how much will earth warm in the next century?) and about some things about which there really is no doubt (what’s the source of increased atmospheric CO2?). It’s far too easy to get suckered by the misinformers, and there’s no shame in that because they are so good at it. Step carefully, and be skeptical of the so-called “skeptics.”

    Probably the best website for reliable scientific information is RealClimate, a blog about climate science run by actual working climate scientists. Probably the best website for debunking bunk is SkepticalScience.

    Pay no attention to remarks about how one or another group (physicists, programmers) tend to be more “arrogant” than another. As far as I can see, arrogance doesn’t respect any occupational classification.

    Trusting in the truth of the matter is hard, in large part because misinformers have deliberately made it so. If you’re interested in what real authorities have to say, consider that the National Academy of Science, the Royal Society (the national science academy of Great Britain, probably the oldest and most respected of all such organizations), in fact the national science academies of over 30 countries, have all stated publicly that global warming is real, it’s caused by human activity, and it’s dangerous. The number of national science academies which have publicly expressed disbelief is: zero.

    Good luck, and if you have more questions, be bold.]

  79. Igor Samoylenko


    With regards to MWP, have a look at this summary paper by Bradley et al *. There is a whole section on MWP (6.5 The Medieval Warm Epoch and the Little Ice Age). It is an excellent summary of the available evidence (as well as the history etc).

    The paper is not very recent and there have been more reconstructions since then but the general conclusions still hold. For more recent summary of all the available evidence you can of course refer to the Fourth Assessment report by the IPCC (see this section for example).

    * R.S. Bradley, K.R. Briffa, J.E. Cole, M.K. Hughes & T.J. Osborn (2003) The Climate of the Last Millennium.

  80. I’m not buying the theory that volcanoes are producing more co2 than humans either. Just nonsense.