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Plimer’s homework assignment

Filed under: — gavin @ 24 August 2009

Some of you may be aware of George Monbiot’s so-far-unsuccessful attempt to pin down Ian Plimer on his ridiculous compendium of non-science. In response to Monbiot’s request for explanation and sources for some of Plimer’s more bizarre claims, Plimer has responded with a homework assignment that is clearly beyond even his (claimed) prowess. This is quite transparently a device to avoid dealing with Monbiot’s questions and is designed to lead to an argument along the lines of “Monbiot can’t answer these questions and so knows nothing about the science (and by the way, please don’t notice that I can’t cite any sources for my nonsense or even acknowledge that I can’t answer these questions either)”. (Chris Colose and Greenfyre have made similar points). It’s also worth pointing out as Andrew Dodds has done that each question is actually referencing a very well known contrarian and oft-debunked argument, but dressed up in pseudo-scientific complexity.

However, as a service both to Plimer and Monbiot (as well as anyone else interested), we give a quick scorecard on the relevance, actual scientific content (whether the questions can actually be answered) and sources for discussion for each of the, to be charitable, ‘odd’ questions. For relevance, we grade each question on a scale from 0 to 5, 0 being irrelevant to the issue of detection and attribution of 20th Century climate change, 5 being extremely relevant. For scientific content, we rate the reasonableness of the question posed (i.e. does it make any sense at all), from A to F (A being a very well posed question, F making no sense). For sources, we generally point to a paper or discussion that addresses the real issue.

  1. From the distribution of the vines, olives, citrus and grain crops in Europe, UK and Greenland, calculate the temperature in the Roman and Medieval Warmings and the required atmospheric CO2 content at sea level to drive such warmings. What are the errors in your calculation? Reconcile your calculations with at least five atmospheric CO2 proxies. Show all calculations and justify all assumptions.
    • Relevance: 0 – poor. Basic logical fallacy. The existence of prior warm periods that may have been caused by different effects (such as solar changes, orbital variation, continental configuration etc.) does not imply that the human-caused increase in CO2 is not causing warming now.
    • Scientific Content: D – phenology (the distribution and timing of species) can potentially be useful for tracking climate changes, but it is just one of many different types of proxy information available, and has its own regional, temporal, and seasonal limitations. Even more problematic, it is well known that the patterns of surface temperature variability during the “MWP” – more accurately, the Medieval Climate Anomaly (MCA) – and LIA periods were spatially quite heterogeneous, and a record at one or two locations generally tells us very little if anything about global patterns. Even a cursory examination of the relevant recent literature (for instance, Osborn and Briffa, 2006) reveals that the pattern of warmth during the Medieval era was far regional in nature, and does not approach the truly global scale of warmth evident in recent decades.
    • Sources: Greater extent of vineyards today in England than in medieval times. Ice core records. Incoherence of the Medieval warm period.
  2. Tabulate the CO2 exhalation rates over the last 15,000 years from (i) terrestrial and submarine volcanism (including maars, gas vents, geysers and springs) and calc-silicate mineral formation, and (ii) CH4 oxidation to CO2 derived from CH4 exhalation by terrestrial and submarine volcanism, natural hydrocarbon leakage from sediments and sedimentary rocks, methane hydrates, soils, microbiological decay of plant material, arthropods, ruminants and terrestrial methanogenic bacteria to a depth of 4 km. From these data, what is the C12, C13 and C14 content of atmospheric CO2 each thousand years over the last 15,000 years and what are the resultant atmospheric CO2 residence times? All assumptions need to be documented and justified.
    • Relevance: 0 – pure misdirection.
    • Scientific Content: F – We know what CO2 and CH4 levels have been over the last 15,000 years and they oscillated within about 10 ppmv (CO2) and 100 ppbv (CH4) of their Holocene values since the start of the current era – until the industrial period (around 1750) since when CO2 has increased by 35%, and methane concentrations have more than doubled. In each case the values being measured today are way higher than anything measured in 800,000 years of ice core records, and likely higher than anything since the Pliocene (~3 million years ago). The idea that bacterial methane production at 4km in the Earth’s crust has anything to with this is laughable.
    • Sources: IPCC FAQ is all that is required. Do volcanoes produce more CO2 than human activity? Not even close.
  3. From first principles, calculate the effects on atmospheric temperature at sea level by changes in cloudiness of 0.5%, 1% and 2% at 0%, 20%, 40%, 60% and 80% humidity. What changes in cloudiness would have been necessary to drive the Roman Warming, Dark Ages, Medieval Warming and Little Ice Age? Show all calculations and justify all assumptions.
    • Relevance: 3 – clouds certainly have an effect on climate and understanding their variability is the subject of much research.
    • Scientific Content: F – The question makes no sense. Clouds at 0% humidity? Is humidity supposed to be globally uniform? And where should these cloud changes occur? The change for low-level clouds will be of the opposite sign to changes in high level clouds, and changes in the Arctic will give different answers than changes in the tropics. It should go without saying that Plimer is mistakenly assuming that he has accurate information for global temperatures over 2000 years.
    • Sources: Cloud Feedbacks in the Climate System.
  4. Calculate the changes in atmospheric C12 and C13 content of CO2 and CH4 from crack-seal deformation. What is the influence of this source of gases on atmospheric CO2 residence time since 1850? Validate assumptions and show all calculations.
    • Relevance: 0 – completely irrelevant.
    • Scientific Content: F – for those that don’t know ‘crack-seal deformation’ is a geologic process that causes the veins of crystals/minerals etc. in many rock types. (see here). Its relevance to atmospheric concentrations and isotopic composition is absolutely zero. It has no influence on atmospheric residence time – whether since 1850 or at any time in the past.
    • Sources Discussions of the actual carbon cycle and the real influences upon it.
  5. From CO2 proxies, carbonate rock and mineral volumes and stable isotopes, calculate the CO2 forcing of temperature in the Huronian, Neoproterozoic, Ordovician, Permo-Carboniferous and Jurassic ice ages. Why is the “faint Sun paradox” inapplicable to the Phanerozoic ice ages in the light of your calculations? All assumptions must be validated and calculations and sources of information must be shown.
    • Relevance: 0 – (again). The acknowledged climate changes in the past caused by natural events in no way implies that human effects are negligible today. Does the existence of forest fires caused by lightning imply that arson can never happen?
    • Scientific Content: C – There is a lot of interesting science related to deep time, but any discussion of such changes must be prefaced with the acknowledgment that our knowledge of greenhouse gases, temperatures or any other potential forcing or response is very limited compared to what we know about climate today or even in the last ice age. Given that we don’t know precisely what CO2 levels were (let alone CH4, N2O, ozone, aerosols, ice sheet configurations, vegetation distribution etc.), the attributions of climate change at this distance is speculative at best.
    • Sources: The faint young sun paradox.
  6. From ocean current velocity, palaeotemperature and atmosphere measurements of ice cores and stable and radiogenic isotopes of seawater, atmospheric CO2 and fluid inclusions in ice and using atmospheric CO2 residence times of 4, 12, 50 and 400 years, numerically demonstrate that the modern increase in atmospheric CO2 could not derive from the Medieval Warming.
    • Relevance:1 – There are amplifying feedbacks between climate and CO2 – which are most evident in the long ice cores from Antarctica, but this argument is trivial to dismiss without any recourse to ocean current velocities etc.
    • Scientific Content:D – You can calculate the change in CO2 per deg C global warming over long (multi-centennial) timescales from the ice age data – it’s roughly 100ppmv/5ºC = 20 ppmv/ºC. The increase in atmospheric CO2 in the last 200 years is now about 110ppmv, implying that any natural driver would have need to have been more than 5ºC natural warming in recent centuries. This would have been noticed by someone.
    • Sources: None required.
  7. Calculate the changes in the atmospheric transmissivity of radiant energy over the last 2,000 years derived from a variable ingress of stellar, meteoritic and cometary dust, terrestrial dust, terrestrial volcanic aerosols and industrial aerosols. How can your calculations show whether atmospheric temperature changes are related to aerosols? All assumptions must be justified and calculations and sources of information must be shown.
    • Relevance: 4 – aerosols are an important climate forcing, and their history through time (even in the 20th Century) are quite uncertain.
    • Scientific Content: C – Calculating the impacts of aerosols is quite hard, first because we don’t have great records for their distribution through time and space, and secondly there are uncertainties in how the mix with each other and how they interact with clouds. Forcing estimates for the human-caused changes in aerosols over the 20th Century therefore have quite large uncertainties associated with them and are a principle reason why attempts to constrain climate sensitivity from the recent record along have not been very successful. Volcanic effects are however quite well characterised, and actually provide one of the many lines of evidence for why GCM simulations are reasonable since they get the right magnitude and character of the volcanic effects on climate. However, there is no evidence whatsoever for large changes in interstellar dust changes in recent millennia and trying to pin recent warming on that is really grasping at straws.
    • Sources: Climate sensitivity and aerosol forcings.
  8. Calculate 10 Ma time flitches using W/R ratios of 10, 100 and 500 for the heat addition to the oceans, oceanic pH changes and CO2 additions to bottom waters by alteration of sea floor rocks to greenschist and amphibolite facies assemblages, the cooling of new submarine volcanic rocks (including MORBs) and the heat, CO2 and CH4 additions from springs and gas vents since the opening of the Atlantic Ocean. From your calculations, relate the heat balance to global climate over these 10 Ma flitches. What are the errors in your calculations? Show all calculations and discuss the validity of any assumptions made.
    • Relevance: 0 – again more misdirection. The throwing around of irrelevant geologic terms and undefined jargon is simply done in order to appear more knowledgeable than your interlocutor. The argument appears to that climate is changing due to tectonically slow changes the direct heat input from ocean sea floor spreading. This is absurd.
    • Scientific Content: F.
    • Sources: Definition of ‘flitch’.
  9. Calculate the rate of isostatic sinking of the Pacific Ocean floor resulting from post LGM loading by water, the rate of compensatory land level rise, the rate of gravitationally-induced sea level rise and sea level changes from morphological changes to the ocean floor. Numerically reconcile your answer with the post LGM sea level rise, oceanic thermal expansion and coral atoll drilling in the South Pacific Ocean. What are the relative proportions of sea level change derived from your calculations?
    • Relevance: 2 – pretty much irrelevant.
    • Scientific Content: C – isostatic issues in sea level are important on long time scales, and there is still an effect today from the deglaciation 15000 years ago. It contributes a decrease of about 0.3 mm/yr to the global sea level rise, compared to 3 mm/yr total (i.e. about 10%). If the idea was to imply that current sea level rise is simply the response to the deglaciation, then it was completely misleading.
    • Sources: Reconciliation of the sea level rise, thermal expansion and ice melt.
  10. From atmospheric CO2 measurements, stable isotopes, radiogenic Kr and hemispheric transport of volcanic aerosols, calculate the rate of mixing of CO2 between the hemispheres of planet Earth and reconcile this mixing with CO2 solubility, CO2 chemical kinetic data, CO2 stable and cosmogenic isotopes, the natural sequestration rates of CO2 from the atmosphere into plankton, oceans, carbonate sediments and cements, hydrothermal alteration, soils, bacteria and plants for each continent and ocean. All assumptions must be justified and calculations and sources of information must be shown. Calculations may need to be corrected for differences in 12CO2, 13CO2 and 14CO2 kinetic adsorption and/or molecular variations in oceanic dissolution rates.
    • Relevance: 5 – the carbon cycle is actually a key issue.
    • Scientific Content: A – understanding the carbon cycle given multiple constraints on the carbon fluxes (including some of the issues raised in the question) is important in showing that the ~35% rise in CO2 since ~1750 is in fact anthropogenic. This has been shown numerous times to be consistent with the known human emissions, increases in oceans and terrestrial carbon, the decrease in 14C content of the atmosphere, the decrease in 13C content in the atmosphere, the decrease in O2 in the atmosphere.
    • Sources: Read the FAQ.
  11. Calculate from first principles the variability of climate, the warming and cooling rates and global sea level changes from the Bölling to the present and compare and contrast the variability, maximum warming and maximum sea level change rates over this time period to that from 1850 to the present. Using your calculations, how can natural and human-induced changes be differentiated? All assumptions must be justified and calculations and sources of information must be shown.
    • Relevance: 4 – detection and attribution of climate change is an important issue.
    • Scientific Content: B – First principles calculations of climate variability are most closely approximated by GCMs and multiple modelling groups have done various Holocene simulations. Attribution of any climate changes requires model simulations with and without each particular forcing and for the Holocene, this involves changes in the orbit, greenhouse gases, solar, meltwater regimes, ice sheet change, aerosols etc. and a comparison of the signature of the responses with patterns observed in the real world. However, comparable data to 20th Century sea levels or temperature changes are not available going back to the beginning of the Holocene.
    • Sources: Attribution of mid-Holocene hydrologic changes to orbital forcing. Attribution of patterns of cooling at 8.2 kya to drainage of Lake Agassiz. Attribution of pre-industrial variability over the last millennia to solar and volcanic forcing (IPCC Ch8, p680+).
  12. Calculate the volume of particulate and sulphurous aerosols and CO2 and CH4 coeval with the last three major mass extinctions of life. Use the figures derived from these calculations to numerically demonstrate the effects of terrestrial, deep submarine, hot spot and mid ocean ridge volcanism on planktonic and terrestrial life on Earth. What are the errors in your calculations?
    • Relevance: 1 – irrelevant. Has nothing to do with current causes of species extinction nor sources of CO2.
    • Scientific Content: D – insufficient data exist to infer atmospheric composition, nor the sources of any hypothesised fluxes. We think that it is likely that mass extinctions are probably bad for “planktonic and terrestrial life on Earth” with very little error.
    • Sources: This is a good intro to the P/T extinction event which is fascinating even if mostly irrelevant to today.
  13. From the annual average burning of hydrocarbons, lignite, bituminous coal and natural and coal gas, smelting, production of cement, cropping, irrigation and deforestation, use the 25µm, 7µm and 2.5µm wavelengths to calculate the effect that gaseous, liquid and solid H2O have on atmospheric temperature at sea level and at 5 km altitude at latitudes of 20º, 40º, 60º and 80ºS. How does the effect of H2O compare with the effect of CO2 derived from the same sources? All assumptions must be justified and calculations and sources of information must be shown.
    • Relevance: 3 – radiative transfer is a key issue.
    • Scientific Content: F – the question as it stands makes no sense. How can using fossil fuel emissions of CO2 allow you to calculate the impact of total H2O? And why only three wavelengths? You would need the whole atmosphere distribution of water (in all three phases and which doesn’t exist outside a model) in order to calculate the radiative fluxes, and a full GCM to calculate all the other fluxes that influence the temperature. If Plimer is actually alluding to the impact of the direct injection of water vapour into the atmosphere from the combustion of hydrocarbons, then this makes even less sense since the perturbation time for water vapour is measured in days (rather than decades to centuries for CO2) and the relative importance of anthropogenic fluxes is much much less.
    • Sources: Importance of water vapour and clouds compared to CO2 for the total greenhouse effect (roughly, 50%, 25% and 20% once overlaps are apportioned). Complete irrelevance of anthropogenic addition of H2O. Calculation of radiative forcing for anthropogenic CO2.

In summary, the relevance of these questions is extremely low, and even when the basic question deals with an issue that is relevant, the question itself is usually nonsensical and presupposes many assumptions that are certainly not a given (at least in the real world). In fact, for the couple of cases where the scientific content is high, the answer is in contradiction to Plimer’s unstated assumptions. The most obvious use of these questions to support a ‘we don’t know everything, so we must know nothing’ type of argument, which is a classic contrarian trope, and one that is easily dealt with.

These questions have as much to do with a debate on human caused climate change as tribbles have to do with astrobiology. Both are troubling, but for very different reasons.

285 Responses to “Plimer’s homework assignment”

  1. 251
    Rod B says:

    Russell Seitz (249), et al: do you know how one reconciles the surface albedo shown on the T&K diagrams (~7%) with that used in the models (15%)?

  2. 252
    Hank Roberts says:


    > The global average surface albedo is calculated to be 0.150.

    Robock, A., 1980: The Seasonal Cycle of Snow Cover, Sea Ice and Surface Albedo. Mon. Wea. Rev., 108, 267–285.

    Lots of newer papers out there, but every one I checked was paywalled and the number wasn’t in the abstract. Detail matters; some specify ‘land surface’ and some specify other materials. I’d guess someone took the best of those, figured in sun angle and day length on each surface and worked out the number.

    Or maybe someone just put a light meter far enough away and measured all the pixels representing Earth?

  3. 253
    Russell Seitz says:

    re 251:

    By reading the T&K diagram completely,, and noting that advanced 3-D GCM’s use different albedo values for pixels representing different surfaces- a modeling trend whose continuing improvement is to be encouraged.

  4. 254
    Patrick 027 says:

    Re 251 – not sure, and I’d have to review K&T again to corroborate that, but maybe it’s the difference between an area-averaged albedo and the Bond albedo, which is the fraction of sunlight that is reflected/scattered to space (or in this case, would be if the atmosphere were removed). Because of the concentration of snow and ice at high latitudes and in winter, the area-averaged albedo will be higher than the Bond albedo, which including atmospheric effects is the more commonly stated albedo of the Earth (~ 30 %).

  5. 255
    simon abingdon says:

    #250 Mark “Simon, do you know that there is going to be a generally cooling effect from clouds?” No of course I don´t. Passing clouds during the day make you feel colder, but cloudy nights are much warmer than cloudless ones. The study of clouds would need to take into account day and night, the percentage of global cover and whether it varies cyclically, whether the hemispheres differ because of the disparity of the area of their oceans, whether indeed oceanic effects dominate or are outweighed by orographic cloud genesis and so on for page after page of important considerations. Your 50% high clouds 50% low clouds, one feedback +ve one -ve nothing more to say is just pathetic. BTW saying “I sit corrected” is not the right way to make an apology by trying to get a cheap laugh from the rest of the class.

  6. 256
    Steve Chamberlain says:

    Just a heads-up, Plimer’s latest response to George Monbiot looks a lot like he’s trying to squirm out of a tight corner to me:

    Dear Mr Monbiot,

    There are seven versions of Heaven and Earth and only my Australian publisher and I know the differences in diagrams, references and text between the seven. It has taken some time to look at your questions and determine which version was used for compilation of the questions. Can you please confirm that you have actually read Heaven and Earth and that your questions derive from that reading?

    Can you please give me an indication when I will get the answers to my questions of science and why you will not debate me on the Michael Medved radio show?

  7. 257
    TrueSceptic says:

    247 Geoff Wexler,

    Thanks. My calculation was based on very simple assumptions, the point being that even if volcanoes emitted CO2 in quantities (by mass) comparable to the estimated solid ejection, it would take something of Toba size to compare with accumulated anthropogenic emissions.

    But we know that the CO2 ejected by recent, “normal” volcanoes must be orders of magnitude lower than that or we would see the blips in the CO2 measurements, which are nevertheless sensitive enough to show both a seasonal cycle and the negative affect of the cooling caused by, say, Pinatubo.

    Plimer’s claim is not just wrong (it is so wrong that even Martin Durkin was obliged to remove it from TGGWS), it is wrong by orders of magnitude.

    BTW Toba is reckoned to be the biggest eruption in the last 25M years, but happened only about 70k years ago. It is thought to have caused a planet-wide die-off and severely threatened the existence of the human species (numbers might have been reduced to only a few tens of thousands). That is the sort of volcano required to “cough” human-level CO2, and even then only if it produces vastly more CO2 for its size than any recent volcano.

    A professor of geology can not possibly be so ignorant, and why would he make a claim too obviously false even for Durkin?

  8. 258
    Mark says:

    “250 Mark “Simon, do you know that there is going to be a generally cooling effect from clouds?” No of course I don´t.”

    Then why do you think that there is going to be nothing to worry about because clouds are not being modelled as well as you’d like?

    “The study of clouds would need to take into account day and night, ”

    Uh, the amount of day and night is pretty predictable and it’s 50-50 on a decadal average…

    “Your 50% high clouds 50% low clouds, one feedback +ve one -ve nothing more to say is just pathetic.”

    So pathetic you haven’t even thought of it yourself. Or have an answer.

    You want a pacifier to calm you down?

  9. 259
    Doug Bostrom says:

    Steve Chamberlain 3 September 2009 at 5:09 AM

    “…why you will not debate me on the Michael Medved radio show?“

    Plimer’s choice of venues for “debate” is quite astonishing. Michael Medved? A right wing radio talk circus is Plimer’s choice for a reasoned debate?

  10. 260
    Robin Levett says:

    @simon abingdon:

    BTW saying “I sit corrected” is not the right way to make an apology by trying to get a cheap laugh from the rest of the class.

    I didn’t think he needed to make an apology – and since mine was the post to which he replied…

  11. 261
    frankbi says:

    Somewhat off-topic, but here’s a heads-up on the Heartland Institute’s upcoming Fourth International ‘Conference’ on Climate Change. They’ve announced the theme of their ‘conference’:

    The conference’s theme will be “Science versus Alarmism.” The theme reflects (a) the growing divide between what science has to say about the causes, scale, and consequences of climate change, on the one hand, and what politicians and the media say on the other hand; and (b) that the debate is not between “skeptics” and the “consensus of scientists” but between science and alarmism.

    A response to this nonsense from the RealClimatati will be great.


  12. 262
    frankbi says:

    (Also, the inactivists seem to be bent on making this “growing divide between (skeptical) science and alarmism” into a meme: see Climate Depot.)


  13. 263
    Geoff Wexler says:

    Re: #257 TrueSceptic

    Thanks for the reply.

    Sometimes it is worth following through all of the consequences of accepting a false premise. Some of the audience have already ignored a lot of the science, so rejecting a bit more is not a big deal for them. Thus an argument supported by data may perhaps be helped by ‘accepting’ the falsehood and taking it through to the bitter end.

  14. 264
    David B. Benson says:

    TrueSceptic (257) — Mt. Toba supereruption makes not even a blip in the Vostok CO2 concentration records. By the way, I know of no extinction evnets from that event, although it was a near thing for humans and even nearer for Bengal tigers.

  15. 265
    TrueSceptic says:

    264 David,

    Thanks. As Geoff said, I took the idea to the extreme and it still doesn’t work.

    I’m interested in the Toba “biological fall-out”. Do you have info that can’t be found via, say, Wikipedia (where I got my basic figures)?

  16. 266
    Hank Roberts says:

    Plimer appears to be showing off his skill at capturing attention, always drawing attention back to himself, dodging and weaving, and moving the goalposts — as though he were performing purely for his own chosen audience.

    Trolling — it’s not just for newsgroups and weblogs.

  17. 267
    David B. Benson says:

    TrueSceptic (265) — The ash fall in South Asia was extreme, thus Bengal tigers went through a genetic narrowing episode. The article in Scientific American on supereruptions (a few years ago) highlights Mt. Toba, pointing towards a 3–6 years interval of very cold weather. Despite that, there are no extinctions known to me. But India is paleontologically understudied, so there might have been some unique life forms there which were exterpated by the supereruption.

  18. 268
    Laws of Nature says:

    Dear Gavin,

    somehow my initial reply to you #176-comment was not published.
    So, let me try again:
    Thank you very much for your inline comment on this topic. I do understand that you must feel that this is often discussed and well understood.
    But, please also read carefully what I wrote, because I think to have asked a new question and I am not aware of an answer providing me with the information where I might go wrong . .
    I do not doubt that manmade additional CO2 is a very reasonable suspect as reason for the raise of the atmospheric CO2-concentration, but I am not convinced, that the C-isotope composition, the near surface sea water(NSSW) pH-value or your newly brought O-concentration provide any prove beside that they show what we already know: We burn fossil fuel.
    (As said before the NSSW-pH change shows, that in this part of the oceans CO2 is close to eqilibrium to the atmosphere and with isotopes you can follow the human CO2 impact in the reservoirs)

    My question was and is, if the C-isotope-ratio (and the oxygene concentration for that matter) reflects the amtospheric CO2-concentration change or just the amount of burned fuel.

    In a “not very likely to happen-Gedankenexperiment”, you can ask yourself, what will happen, if under the current fuel burn situation aliens would start to take significant amount CO2 out of the atmosphere (without preferring any isotope) . .

    a) if the isotope ratio reflect the change of concentration, it would revere itself as soon as the aliens go to work
    b) if the isotope-ratio (and the oxygene) only reflects the relative amount of burned CO2, it would continue with a similar tendency s without any alien.

    I tend to say b) is what would happen indicating what I said before:
    Oxygene levels and C-isotope-ratios only reflect the simple fact:
    We burn fossil fuel! They do not reflect the change of atmospheric CO2-concentration and cannot be used as a proof of that!

    All the best,

    P.S.: Of course you can come up with a more realistic model, where the amount of CO2 in the amtmosphere decreases, while we still burn fuel like sequestering CO2 into the deep sea or so, but this is not relevant for my problem.

    [Response: I have no real idea what you are asking here (sorry). If aliens or anyone takes out CO2 by magic (or air capture), this won’t effect the isotope ratios even if it reduces CO2 back to pre-industrial levels. Of course all of the metrics we have for the carbon cycle are consistent with the source of the carbon coming from industrial activity (since that is where it has indeed come from) – they are however inconsistent with any other source of the carbon or indeed any alien-derived messing about with the carbon cycle (unless they are removing all the anthropogenic carbon and replacing it with carbon of exactly the same composition- at which point one might well ask what the point is in discussing it). – gavin]

  19. 269
    Marion Delgado says:

    BTW thanks for this Gavin. People like you and James Hansen do the thankless work that used to be a bit less thankless when Sagan et al. were doing it.

  20. 270
    Deep Climate says:

    I’ve received a (wholly inadequate) response from the Australian Broadcasting Corporation about my complaint concerning Plimer’s “Unleashed” online piece.

    The Tony Jones interview was just one of several ABC pieces that had previously demolished Plimer’s various assertions. Yet ABC claims that the publication of Plimer’s “Unleashed” piece was in accord with the ABC’s Code of Practice requirement to “take reasonable steps to ensure factual accuracy”. I beg to differ.

  21. 271
    Sekerob says:

    Gosh, it would not look good if Plimer’s volcanic burp would raise the CO2 by another 1 in 10,000

  22. 272
    Ray Ladbury says:

    Laws of Nature,
    Your post was rether difficult to parse. However, you need to consider the evidence and what the evidence implies. First, what is measured at Mauna Loa is the CO2 concentration–the whole enchilada, not just the portion with C-13 or C-14. We know it is increasing. Now as to the isotopic data–we know the C-13 and C-14 contents are decreasing. This implies a that the CO2 is from a fossil source–and the largest source of fossil carbon is burning of fossil fuels. That’s it.

    As to ocean pH, that has to fall as atmospheric CO2 rises–just chemical physics.

  23. 273
    Marion Delgado says:

    Plimer’s field is not climate. What he teaches is mining geology (what a very astute commenter on a science blog described as part of “economic geology”). You can’t really conclude anything about how he is as an academic instructor from his shameful and ignorant behavior writing and talking about climate.

    It shouldn’t be surprising, even, that he knows less than many of us commenting on science blogs about climate. He’s made no effort to educate himself, because he knows it would undercut his certainty when he talks to the public.

    It’s a good idea to somehow deduct the things people “know” that just aren’t true from their net knowledge. If you know, for instance, that not all vertebrates use X and Y chromosomes, but you also think the Earth is 10,000 years old and species were created specially, you know less than I do if all I know is that species came mostly from natural selection and random mutation. It takes 10 minutes and 3 or 4 examples to get me up to speed on what you know. Getting you up to speed on what I know might take years or be impossible.

    Also: “It’s very difficult to get a man to understand something when his salary depends on him not understanding it.” – Upton Sinclair.

  24. 274

    #268 Laws of Nature

    I’m not sure it is possible for you to be more obfuscative, though I am confident you will at least attempt to prove me wrong.

  25. 275
    Eamon says:


    I hope you don’t mind, but I’m going to post that link over on Deltoid, as it’s pure gold.

  26. 276
    abi says:


    This might be of interest to you. S4 deals with ice, but you need to wait until next week to find out.

  27. 277
    Eli Rabett says:

    The CHANGE in C isotope ratios reflects fossil fuel burning just as the CHANGE in oxygen concentrations does.

  28. 278
    Laws of Nature says:

    #Re 277
    Dear Eli Rabett,
    I agree to that, my question was, if you can see anything else form that numbers?
    Otherwise it is like I called it “complicated wording”
    for “we burn fuel”.
    While the assumption “burning fuel leads to rising atmospheric CO2 concentration” is reasonable, my question was and is if and how the isotope analysis provide any prove or futher information for that.

    All the best regards,
    P.S.: Dear Moderator, this question seems to interest not only me, please allow an open discussion on it, it is a very important and interesting topic!

  29. 279
    Silk says:

    #Re 278

    The IPCC 4th Assessment Report answers your question very clearly on page 139 of the Working Group I report. It’s available online from

    See also the explaination from the 3rd Assessment report in 2001 (also available online). Prentice, I.C., et al., 2001: The carbon cycle and atmospheric carbon dioxide.
    In: Climate Change 2001: The Scientific Basis. Contribution of Working
    Group I to the Third Assessment Report of the Intergovernmental Panel
    on Climate Change [Houghton, J.T., et al. (eds.)]. Cambridge University
    Press, Cambridge, United Kingdom and New York, NY, USA, pp. 184–238.

  30. 280
    TheAnalyst says:

    You really shot yourself in the foot with question number one, because your attempted justification actually points more or less towards the inevitable hole within your argument:

    “The existence of prior warm periods that may have been caused by different effects (such as solar changes, orbital variation, continental configuration etc.) does not imply that the human-caused increase in CO2 is not causing warming now. ”

    Could just as easily read:

    The proven existence of prior warm periods that may have been caused by different effects (such as solar changes, orbital variation, continental configuration etc.) does imply that the human-caused increase in CO2 is not causing warming now (Or Ever). -(ie, that any potentially observed warming is natural in source).

    If you have a proven pattern, and proven causes and effects, then ignoring them as the most likely culprits is quite wrong indeed. Such does not have to be scientific in nature either, but rather common sense based and logical. Sometimes individuals become far too caught up in minute field-oriented details, which subsequently prevents the observance of the vast and simple reality (Or likelihood thereof).

    Please, by all means, carry on with your debate and analysis. I simply felt the need to point out the aforementioned.

    [Response: By your logic, since lightning is proven to set forest fires there is no point in considering the possibility of arson. Despite there being cc-tv coverage of the suspect leaving the area carrying an empty kerosene can and a big box of matches. By all means, continue in your ignorance of basic logic. – gavin]

  31. 281
    CM says:

    #268, 278 “Laws of Nature”,

    Your question is neither interesting nor important. Ray Ladbury (#272) has explained your mistake to you. You are right that an increase in atmospheric CO2 concentration does not follow from carbon isotope ratios. Noone says it does. The CO2 increase is measured directly directly (you can read how it’s done at Mauna Loa). The isotope ratio is not an index of the concentration, it is a fingerprint of the source.

    Here’s a parable of two shepherds. You have 10,000 sheep, 1% of which are black. Your neighbor also has 10,000 sheep, 2% of which are black. One dark and cloudy night later, the b/w ratio of your neighbor’s sheep has dropped to 1.67%. That doesn’t say anything about how many sheep your neighbor’s got. So you count’em. Your neighbor now suddenly has 15,000 sheep. Moreover, you are down to 5,000 (the b/w ratio is unchanged; in the dark they all look grey, so the thief got a random sample). Do the math.

    (How would you know the b/w ratio of your neighbor’s sheep before you’ve counted them? Maybe by measuring the sheep albedo on your neighbor’s pastures…)

  32. 282
    Ron Taylor says:

    TheAnalyst (#280)- The fundamental error in your logic makes one wonder what kind of analyst you are. With your understanding of logic (as well as the science), you should be careful about accusing a practicing scientist of having a “hole in your argument.” If you had posted the same point humbly and respectfully, your statement would have been accepted as naive, but sincere, and would not have made you look quite so foolish.

  33. 283
    Mark says:

    “By your logic, since lightning is proven to set forest fires there is no point in considering the possibility of arson.”

    Or murder.

    After all, people are dropping down dead left and right all the time.

    Hence murder is impossible.

  34. 284
    Andy says:

    As the dictum goes: “One thousand scholars can not answer the question of one ignorant student who does not wish to learn”.

  35. 285
    Andy says:

    Obfuscation is ssupreme.

    As in the dictum, spread by tobacco industry lobbyists (some of whom transmuted to the climate debate) “DOUBT IS OUR PRODUCT”.