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By William and Gavin

On Thursday March 8th, the UK TV Channel 4 aired a programme titled “The Great Global Warming Swindle”. We were hoping for important revelations and final proof that we have all been hornswoggled by the climate Illuminati, but it just repeated the usual specious claims we hear all the time. We feel swindled. Indeed we are not the only ones: Carl Wunsch (who was a surprise addition to the cast) was apparently misled into thinking this was going to be a balanced look at the issues (the producers have a history of doing this), but who found himself put into a very different context indeed [Update: a full letter from Wunsch appears as comment 109 on this post]

So what did they have to say for themselves?

CO2 doesn’t match the temperature record over the 20th C. True but not relevant, because it isn’t supposed to. The programme spent a long time agonising over what they presented as a sharp temperature fall for 4 decades from 1940 to 1980 (incidentally their graph looks rather odd and may have been carefully selected; on a more usual (and sourced!) plot the “4 decades of cooling” is rather less evident). They presented this as a major flaw in the theory, which is deeply deceptive, because as they and their interviewees must know, the 40-70 cooling type period is readily explained, in that the GCMs are quite happy to reproduce it, as largely caused by sulphate aerosols. See this for a wiki-pic, for example; or (all together now) the IPCC TAR SPM fig 4; or more up-to-date AR4 fig 4. So… they are lying to us by omission.

The troposphere should warm faster than the sfc, say the models and basic theory. As indeed it does – unless you’re wedded to the multiply-corrected Spencer+Christy version of the MSU series. Christy (naturally enough) features in this section, though he seems to have forgotten the US CCSP report, and the executive summary which he authored says Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This significant discrepancy no longer exists because errors in the satellite and radiosonde data have been identified and corrected. New data sets have also been developed that do not show such discrepancies. See-also previous RC posts.

Temperature leads CO2 by 800 years in the ice cores. Not quite as true as they said, but basically correct; however they misinterpret it. The way they said this you would have thought that T and CO2 are anti-correlated; but if you overlay the full 400/800 kyr of ice core record, you can’t even see the lag because its so small. The correct interpretation of this is well known: that there is a T-CO2 feedback: see RC again for more.

All the previous parts of the programme were leading up to “so if it isn’t CO2, what is it?” to which their answer is “solar”. The section was curiously weak, and largely lead by pictures of people on beaches. It was somewhat surprising that they didn’t feature Svensmark at all; other stuff we’ve commented on before. Note that the graph they used as “proof” of the excellent solar-T connection turns out to have some problems: see figure 1c of Damon and Laut.

Along the way the programme ticked off most of the other obligatory skeptic talking points: even down to Medieval English vineyards and that old favourite, volcanoes emitting more CO2 than humans.

It ended with politics, with a segment blaming the lack of African development on the environmental movement. We don’t want to get into the politics, but should point out what the programme didn’t: that Kyoto exempts developing nations.

[Also: other discussion at InTheGreen, Stoat, The Guardian and
Media lens.]
[Update: What Martin Durkin really thinks!]
[Update for our german readers: A german version of the “swindle” film was shown on June 11 on German TV (RTL); here is a german commentary by stefan.]

558 Responses to “Swindled!”

  1. 201
    Reid says:

    James asked:

    “Also, may I ask you once again to remember that understanding these past climate cycles is not the same as understanding AGW? In the past (at least the last 50 million years of it, since the PETM), the total amount of CO2 in the system changed very slowly. Now humans have increased the CO2 significantly, in a time so short as to be almost instantaneous in geological terms. We’ve taken a smoothly running system and given it a swift kick: is it going to keep on working as before, do something different (which we may not like), or break down completely? “

    Quite so. But the potential existence of stabilizing feedbacks which have apparently re-balanced the system in eons past has a direct bearing on whether the exogenous forcing of the system through the introduction of CO2 into the atmosphere will have a significant effect on the Earth’s climate or not.

  2. 202
    Ike Solem says:

    Reid, consider another climate feedback in the real world, the albedo effect. On one hand albedo can act as a cooling influence – if more snow falls and stays on the ground in the Northern hemisphere, then the albedo change acts as a postive feedback on an initial cooling signal by reflecting more sunlight back to space; if less snow falls, or snow melts (exposing bare ground) then the albedo change acts as a positive feedback on an initial warming signal. So, why don’t small changes in albedo immediately lead to rapid global warming or rapid global cooling? Well, because there are other factors at play, though albedo seems to play a large role in Northern hemisphere climate variability.

    You also say that “CO2 can only trap heat” – but a blanket traps heat, and also dissipates heat (otherwise, you’d go on warming up forever) – but the blanket creates a layer of warm air near the surface. Imagine looking at someone through an infrared viewer who suddenly wrapped a blanket around themselves – eventually, the outer surface of the blanket would radiate as much energy as person initially did, but perhaps at a longer wavelength. Similarly, CO2 also both absorbs and radiates infrared radiation. This can be detected from space; see for a 2001 discussion.

    It seems that the main issue you are ignoring is that many different feedbacks operate concurrently to affect the climate – and you’re also ignoring the fact that adding massive amounts of fossil fuel carbon to the system changes things quite a bit.

    So, let’s consider the current situation – we add CO2 (or some other infrared absorbing/emitting gas) to the atmosphere of the planet, and we get surface warming, which warms the oceans and the land masses. However, it takes a long time to for the oceans to absorb the extra warmth and to equilibrate with the new atmospheric level of CO2 (which is why we expect the sea level to continue to rise for hundreds of years after CO2 levels are stabilized). However, due to the carbonate buffering system ( ), the oceans don’t simply absorb all the CO2. Likewise, since in our time photosynthesis and respiration appear to be balanced, the biosphere doesn’t absorb the CO2 either – and this was confirmed by Charles Keeling and his measurements of atmospheric CO2 increases since 1958.

    Let’s take another feedback effect that operates concurrently – the water vapor feedback effect due to increased net evaporation – you can also ask, why doesn’t the water vapor keep increasing forever? What removes the water vapor from the atmosphere? (precipitation). Similarly, we can ask what removes CO2 from the atmosphere ? (photosyntheis is one factor) What puts CO2 into the atmosphere? (respiration is one factor). These factors are dependent on other factors – such as nutrient supply and temperature. A good discussion of past CO2 levels relative to today is available at – notice the stability over the 1000 yrs preceding 1750.

    To summarize, the various feedbacks are far more complicated than you are assuming they are, and they interact with one another. Take population growth, as another example – you can say that population growth is always a positive feedback, since more individuals have more offspring, and so on – but population growth can also create a strong negative feedback, as when a population overshoots the carrying capacity of its ecosystem, at which point it severely crashes – due to additional factors.

  3. 203
    Reid says:

    Marcus: looked at your system. It does not always have an equilibrium, depending on how you choose the parameters. When you choose them right, you have a globally stable equilibrium point and, you are not getting a positive feedback system in the sense of an unstable, self-sustaining system (i.e., in the only sense that matters).

    Please read the above discussion points with Gavin. Positive/negative means nothing in terms of stability applied to discrete time gains. In your system, the system perturbation matrix about the equilibrium is

    Phi = [0 0 1 ; -Aconstant/temp(equilibrium)^2 0 0 ; 0 -1 0]

    where semicolons separate the rows. The eigenvalues of this matrix all have magnitude less than unity at the equilibrium point, when it exists, i.e., this is what everybody on the planet other than climate scientists, apparently, would analogize to a “negative feedback” system.

    My intemperate criticism in previous comments still stands. In this simple system, the temperature is directly proportional to the CO2 concentration but, I would expect the real physics to dictate that the rate of heat accumulation includes a term which is proportional to the CO2 concentration and the temperature is proportional to that. Since CO2 cannot dissipate the heat, it cannot have a stabilizing influence on its own.

  4. 204
    Steve Bloom says:

    Re #198: Reid, the simple answer is that the glacial cycles are triggered by high-latitude insolation changes that determine whether there is enough summer melting to overcome winter accumulation and thus result in a net increase or decrease of snow. Starting with a change in albedo, this process leads to a complex of feedbacks (prominently including CO2 changes) that ultimately have the effect that is apparent in the ice core record. Deglaciations are much quicker since ice melting is a “wet” process whereas ice accumulation can only occur relatively slowly. Your point about historical norms is useful, but note that the Pleistocene is normal only from the myopic standpoint of human lifetimes.

  5. 205
    Hank Roberts says:

    Reid, you’re talking theory, I’m talking observations.
    Plankton cooled the PETM greenhouse.

    Evolution responds to climate change, yes, but not overnight.

    Haptophytes (e.g. Emiliania): Common, ecologically important algae
    with a red secondary plastid. Many haptophytes are covered in elaborate
    calcareous scales called coccoliths, which are a primary component of
    chalk sediments such as the white cliffs of Dover.

    This time around, we have a different kind of plankton — shell-forming, using CO2 to make calcite and aragonite shells. The pteropods evolved in the last 200k years, relatively quite recently. They’re more efficient at removing CO2 because they’re global rather than restricted to shallow near-continental shelf waters, and because the shells sink. They’re less efficient because they can’t make shells once the pH of the ocean reaches where it’s expected to be by 2100 — that’s chemistry, solubility, not climate change physics.

    You’d know this if you’d read any of the references.

    None of this matters on the human time scale; it’s on the human time scale we’re producing the huge spike in excess CO2, far more than biogeochemical cycling is equipped to handle at this rate of change.
    Hence the current excursion.

    Yes, nature is responding. But === read some of Margulis’s work, it’s an astonishingly complicated reassortment of living things to handle changes like this.

    From the same paper linked above:

    “How many secondary endosymbioses?
    With the realization that secondary-plastid-
    containing algae constitute a large proportion of the
    diversity of photosynthetic eukaryotes comes an
    important question: how often have these mergers
    happened? The integration of endosymbiont and host
    is an immensely complex series of events that has a
    formidable effect on both host and endosymbiont. It
    involves massive transfers of DNA between genomes,
    the development of a sophisticated protein-targeting
    machinery and a substantial reorganization of core
    and secondary metabolism. Untangling these events
    and understanding their effects on eukaryotic
    evolution requires fundamental knowledge of which
    algal lineages arose from the same endosymbiotic
    partnerships and which arose independently……”

    Yes, it’s happening now:
    Symbiont-Bearing Foraminifera: Harbingers of Global Change?
    P Hallock – Micropaleontology, 2000 – JSTOR

  6. 206
    hopp says:


    How much “new” CO2 did these eruptions release into the atmosphere?

    Tambora 1815
    Krakatau 1883
    Santa Maria 1902
    Mount Pelee 1902
    St. Helens 1980
    Nevado del Ruiz 1985
    Pinatubo 1991

    Somehow I don’t think it adds up only to 1% of man made CO2 emissions. I have read some scientists say that one such major eruption would release as much CO2 as ten years of human activity, but I don’t believe that either. What could be reliable estimations? And isn’t three major eruptions inside 11 years 1980,1985,1991 very rare in our age and doesn’t this correlate with the warming cycle?

    Then it’s said that there haven’t been this much CO2 in the atmosphere since 600,000 years ago. Well… 640,000 years ago the super Volcano of Yellowstone erupted with the power of 2,000 St. Helens, burying half of the North American continent in thick ash. How much CO2 was released? How did it affect the atmosphere, temperatures…?

    [Response:If volcanoes pumped out vast amounts of CO2, don’t you think we’d see spikes in the CO2 record? But we dont: e.g. here – William]

  7. 207
    tony says:

    I am put in mind of Ptolmy who placed the earth at the centre of the universe,a view unchalleged for a millenia. In 1350 Giovanni de Dondi made a magnificent working model of Ptolmy’s universe, wheels within wheels made the planets turn back on themselves as they appeared to do when observed from earth.
    Brilliant, incredibly complex but wrong, in 1543 Copernicus put the sun at the centre of the solar system. The convolutions of the T/CO2 lag explantions rival Mr de Dondi’s clock, when just by saying the sun ‘s output varies, we explain the ice core record.

  8. 208
    Dave Rado says:

    when just by saying the sun’s output varies, we explain the ice core record.

    Except that we don’t!

  9. 209
    tony says:

    As the audience responds at an english pantomine – OH YES WE DO!!

  10. 210
    Dave Rado says:

    But I didn’t find any answer in RC to a couple of important question raised – how many actual practising scientists are in the 2500 IPCC “consensus”? How many have resigned in the manner of the malaria expert, or asked to have their names removed as contributors?

    The answer to the second question is two, I believe – Reiter and Landsea. I don’t know the answer to the first, though I believe it is just over 2,000 – perhaps someone else can help with that.

  11. 211
    Dave Rado says:

    Hi Tony – can you point to any peer reviewed evidence for your statement?

  12. 212
    tony says:

    “There is no reason to believe that this 10,000-year-old cycle of solar-induced warming and cooling will change. Dr. Sallie Baliunas, an astrophysicist with the Harvard-Smithsonian Center for Astrophysics and one of the nation’s leading experts on global climate change, believes that we may be nearing the end of a solar warming cycle. Since the last minimum ended in 1715, Baliunas says there is a strong possibility that the Earth will start cooling off in the early part of the 21st Century.”

    I picked this at random from the internet, I have no idea who Dr. Baliunas is. My point is that his theory is more beleivable than yours.
    Until this documentary,I had never heard of the T/CO2 lag, and went along with the herd on the causes of global warming. IMHO your explanations of the lag do not stand up.

    [Response: He is a she. Just another reason to check your sources. -gavin]

  13. 213
    Mike Forster says:

    Being relatively new to researching climate issues and accordingly having just read the above 200 or so blogs, I’m still in broad terms none the wiser having here found a collection of conflicting views, interpretations and opinions as opposed to any firm conclusions. Do we really have anything much more than a mere inkling as to what drives the climate through the ages?

    I personally found the Swindle programme entertaining in that it did, if little else, present a rather different view of things to that currently expounded by (what I suspect to be) grant-hungry scientists and tax-hungry band-wagon-vote-driven politicans (I’m in the UK BTW). (At the other end of the spectrum – and maybe in response to the Swindle program? – this last Sunday’s Sunday Times here in the UK carried a scare-mongering sensationalist article talking of the dire consequences of a 6C increase in global temp by 2100. The whole article was driven by the meanderings of a scientist called Lynas. How well is this chap regarded within the wider scientific community?)

    [Response: Mark Lynas is a journalist, not a scientist. – gavin]

    OK, so I’m no scientist myself – as will probably become apparent throughout the rest of this blog!. But I do have 3 degrees including a PhD, so I do not unreasonably consider myself able to appraise information in an ordered manner. That said, may I pose some (perhaps naive) questions.

    1. Has it been established beyond reasonable that CO2 has ranged between 180 and 280ppm during and between the last four Ice Ages?

    [Response: Yes. This comes from multiple ice cores. -gavin]

    2. What mechanisms have caused each of the last four Ice Ages to start against the backdrop of increasing global temperatures during the intervening Interglacial periods?

    [Response: Decreases in northern hemisphere summer solar radiation due to changes in the Earth’s orbit (Milankovitch forcing). -gavin]

    3. Now CO2 levels are at 380ppm. One has to assume that much if not all of this extra Co2 is down to us, no? If not what else could it be? In this regard, is there ANY credibility in the assertion as per the Swindle programme regarding the current elevated CO2 figure having rather more to do with the ‘delayed’ effect of the temperature rise in Medieval times rather than the burning of fossil fuels?? If so, is there any evidence that such temporary increases in CO2 have occurred before?

    [Response:All of the increase is anthropogenic. The last time CO2 was so high could have been 3 million years ago (the Pliocene), but possibly not for 25 million years. However, estimates that far back are much more uncertain. Certainly farther back than 800,000 years. Given our understanding of the carbon cycle, it is extremely unlikely that there have been any ‘peaks’ up to 380ppm over that time. – gavin]

    4. The question then is, what effect will this extra 100ppm (and that figure is almost certainly going to increase for a few more decades at least) of CO2 have upon our climate over the next century or two. I read somewhere above that each increase 0f 100ppm CO2 makes far less of a difference in increase of global temperature than did the previous increase of 100ppm oc CO2. If this is correct, then wouldn’t another increase in 100 ppm of CO2 from 380-480 only raise the global temp by a quarter of a degree or so?

    [Response: The impact is controlled by the climate sensitivity – generally given as the warming you expect from a doubling of CO2. This is around 3 deg C from multiple lines of evidence. From 280 to 380 ppm would be expected to give 1.2 deg C, from 380 to 480 around 0.9 deg C – both at equilibrium. You need to add in the other forcings (CH4, O3, CFCs, N2O, aerosols, solar) and take into account of the ocean lag to see where we should be now. However, stabilisation at 480 is an extremely challenging task. – gavin]

    Any and all input in response to the above would be appreciated. I know I’m no scientist so I don’t need reminding by flames! Try to remember that there are rather more people like me out there than people like you in here (-:


  14. 214
    tony says:

    I have just tried to post a random cutting from the internet supporting solar warming, my post was not allowed presuambly because the scientist named is on your list of dirty words.

  15. 215
    Dan says:

    re: A “random cutting from the internet”? Goodness, that is not peer-reviewed scientific evidence. In fact, that is the ultimate example of using a non-scientific reference. Meanwhile, there are many scientific references right here on regarding the non-role of “solar warming”. Just do a simple search at the top of the page. Science is not a simple “random” personal opinion posted on the internet!

  16. 216
    hopp says:

    few more points, before I shut up:

    It is estimated that during the Crecateous period the Earth temperature was 6-14 Celsius warmer than it is today. Atmospheric CO2 levels are estimated to have been 2-4 times (even 6x) higher than today. Unusually high volcanic activity is usually cited as the reason for the warmth. What is the relation to the high CO2 levels? And all in line with the CO2-GW theory… except that just before that period, during the large ice age of 150 million years ago, a time of glaciation and cold temperatures, atmospheric CO2 levels had been just as high. Dr. Giegengack of Penn. who has researched this, suggests that the fluctuations in the gas levels fall out of step with the planetâ��s hot and cold cycles, undermining the claimed supremacy of carbon dioxide, and adds: “People come to me and say, â��Stop talking like this, youâ��re hurting the cause’,

    Isn’t the argument about “spikes” rather speculative? Volcanoes set a convection pattern. CO2 (and other gases) go straight into upper atmosphere. This pattern brings fresh air from the surrounding area. Isn’t it then only logical, that the ground level CO2 stations will not record any spikes? Then the atmosphere has a mixing time of “how long?” and even larger eruptions get averaged, and will not be seen as spikes?

    During the Crecateous period the Earth bloomed with life. Continuous forests of gigantic trees, plants and animals covered all the land area. There was much more rain and there were no vast deserts.

    Is it necessarily the outcome of say 2-3C temperature increase that there will be vast and increased desertation in south? Isn’t it impossible to predict how the weather patterns would be affected? (We are still in the dark what really caused the droughts in 1980’s). Isn’t it also possible that rains will increase and things will turn better in say Africa?

    Things like desertation, hunger etc. are often quoted as the obvious outcome of any 2C+ AGW, but isn’t that also more about the pre-cautionary principle, than exact science to model such outcomes?

  17. 217
    tony says:

    I am going to leave you Ptolmyean climatologists to it, hopefully there are enough Copernicans out there who can put up with the abuse and ridicule so that logic will prevail.

  18. 218

    [[This is where GW falls apart for me, The process that starts the temperature rise is, as above, not understood. At best the C02 is a feedback, so what we are saying is: If we just add c02, without the event that starts the temperature rise, we will get global warming.]]

    That’s just basic radiation physics. Put more CO2 into the air and the ground will be warmer, all else held constant. That’s something we know from lab work dating to 1859.

  19. 219

    [[Yes. But when the market is horrendously distorted by coercively-financed science, then what gets paid for is science that proves what those who want to coerce more money out of taxpayers want to have proved. If you prove that what is happening can only be solved by coercively destroying the free markets that have created the greatest improvements in the quality of human life, then you’re probably proposing a solution that can, at best, be called “evil.” ]]

    As far as I know, nobody is suggesting coercively destroying the free markets. Where did you get that idea?

  20. 220
    Geoff Wexler says:

    BBC2 Newsnight 12th. March 2007
    They devoted a whole slot (perhaps 10 minutes) to the Channel 4 program as if it was a news item.

    It started with a sympathetic introduction by the presenter; there followed a replay of two extended sections from the Channel 4 programme about (a) the lags problem (showing Al Gore with the ice cores) and then (b) the two Danish graphs from Christensen and Lassen. This took up most of the program. They then introduced Paul Reiter on one side and Brian Hoskins from Reading (on the other) who were allowed a highly controlled debate. Hoskins just had time to talk about the lags and positive feedback but was cut short before trying to deal with the other issue of the solar correlations. This latter was most unsatisfactory. But I must admit that Hoskins was wasting time starting a sentence saying that evidence was very strong that “global warming was real”. It struck me that some genuine scientists are too busy to become experts in forensic matters ; why should they? I repeat that Al Gore’s film, good as it was, needs to have a second edition and or a successor by someone else, otherwise his opponents will succeed in confusing everyone. The BBC needs to be told about their propagation of two graphs one which has been cleaned up at the price of a discrepancy between sound and display and the other which has not been cleaned up and which (according to Damon and Laut) has a century long faked section. The correct graphs need to be televised.

  21. 221

    [[If greenhouse gases trap heat from IR, do they also reflect some back? If this is so, is there not a balancing of the two i.e. as the greenhous gases increase the reflection of IR increases, therefore negating the heating effect of greehouse gases?]]

    No. At infrared wavelengths in Earth’s atmosphere, there is almost no reflection or scattering.

  22. 222
    Geoff Wexler says:

    #183 and #189
    Bookeeping of radiation.
    Infra-red radiated from the ground is absorbed by greenhouse gases at higher altitudes where it is much colder. The same gases also radiate both back to the ground and upwards towards outer space where some of it eventually escapes. But radiation is lower at these cold temperatures (Stefan’s law) so the amount eventually lost to space is reduced compared to what it would have been without the greenhouse gases. Furthemore there is a balance between all these effects ; no need to fear that there has been a simple blunder in the bookeeping.

  23. 223

    [[Dude… Think… CO2 can trap heat. It cannot reflect it out to space. It cannot funnel it through a wormhole to another region of space or even another universe. CO2 does not dissipate heat. What you are claiming is fanciful, to say the least. ]]

    CO2 doesn’t exactly “trap” heat. It absorbs infrared light, which heats the CO2 up. The warm CO2 radiates infrared light, some of which goes back to the ground and the rest of which goes to other layers of atmosphere or out to space. The heat isn’t permanently trapped anywhere.

  24. 224

    [[“In order to reach 200 ppm, CO2 concentrations decrease. ”

    It doesn’t matter. At 200 ppm, CO2 traps enough heat to cause a rise in temperature. You said so yourself, on the way up. But somehow, you have convinced yourself that it expels heat when the temperature is decreasing. No. CO2 captures heat. It does not capture cold. It cannot work in the way you specify. CO2 will not reinforce a downward trend.]]

    He’s not talking about how CO2 works as a greenhouse gas. He’s talking about the amount of it in the atmosphere. What the CO2 concentration is does not depend, except perhaps very weakly, on CO2‘s greenhouse action. CO2 decreases in his scenario because the oceans absorb it.

  25. 225

    [[The convolutions of the T/CO2 lag explantions rival Mr de Dondi’s clock, when just by saying the sun ‘s output varies, we explain the ice core record. ]]

    Do we? Cite a source, please, and explain the mechanism you’re talking about. Do you have a graph of Solar output versus temperature on the time scale of the ice cores?

  26. 226
    Andrew Dodds says:

    Re: 216

    You are cartainly correct that there was plenty of life in the Cretaceous, and it was very much warmer. This appears to be a result of several things – higher GHG levels, no ice caps/ocean circulation to the poles, no large mountain areas comparable with Tibet, etc.

    Thing is, sea levels were of the order of 100 meters (300 feet) higher than today.

    It does not matter *what* the climate is – it is just that all of our human infrastructure is built around the current climate, and moving the climate makes a lot of that infrastructure obsolete. Think water, agriculture, house styles, etc..

  27. 227
    Ian Rae says:

    Gavin, I would like to believe you, but some of your statements puzzle me. At one point you say “S+W’s study is incorrect, but even if we discuss that, you can always find another ‘confusing’ reference that we haven’t discussed. This is a real problem, and one where there is not an obvious answer.” You suggest that the “public shouldn’t listen to any one scientist (even me), but the assessments (IPCC, NAS etc.)”. The IPCC is a highly politicized body whose conclusions are signed off by governments, i.e. politicians. Given the whirlwind of AGW in the zeitgeist, one can hardly trust governments to be neutral on this topic.

    Later you respond to a simple question about T-CO2 lag with “The degree of that lag is actually quite uncertain and there is recent paper under review that suggests…” Given the huge amount of NAS & IPCC assessments, which you say people should trust more, why do you reach into a mirky bag of half-reviewed papers which “suggest” something? I may be completely wrong here, but it seems that rather than simply conceding “yes CO2 generally lags T” you resort to another confusing reference which happens to support your position. Surely this simple question about pre-20th century T/C02 lags can be answered better than that.

    I find it hard to believe that thousands of climate scientists are wrong, or caught up in some politicized delusion. If they say AGW is happening then I am prepared to accept that. But the tone used by some here about how “tired” they are of answering the same old questions is quite unhelpful. It’s understandable to be tired, but remember that you are calling for a fundamental change in our civilization that will cost trillions and take decades to accomplish. We need to check and check and check again.

    Anyway, thanks for this site; it’s one of the best on the web. It’s a good regular read.

    [Response: The IPCC is not politicized and the reports are not written by governments – though if it were, anything that got signed up to by countries as diverse as Saudi Arabia, the US and Albania must have something going for it! The reason why it’s on the shelf of every relevant scientist in the field is because it is a thorough and comprehensive assessment of the literature. Please read it – the TAR is online – and judge for yourself. On your second point, I gave you a straight answer. I simply pointed to current discussions that were relevant on which I don’t have an opinion (yet) (though if the lag disappears completely I’ll be quite surprised). It’s not ‘murky’ to acknowledge where the uncertainties and complexities are. -gavin]

  28. 228
    Reid says:

    Thank you Marcus, James, David, Gavin, William, et al, for some very interesting discussions. I have learned a lot. Most prominently, I have learned that when climate scientists speak of “positive feedback”, they really don’t mean “positive feedback” in the sense, well, in the sense that it makes any sense. I came in here thinking that the proposal was that there were actually destabilizing feedbacks in the system and, this would indeed be a dire circumstance in my view. I was convinced that this could not be so because the instability would have already expressed itself in a dramatic and immediately observable way, as such things are wont to do.

    Now, I see that when you say “positive feedback”, you really almost always really mean “negative feedback”. Oddly enough, I simultaneously now find the AGW hypothesis more plausible but less worrisome. I really do believe you fellows need to revise your nomenclature. Feedbacks should be classified based on whether they are stabilizing or destabilizing. In systems described by differential equations, this dividing line occurs when the feedback has a negative or positive sign. Historically, these are the types of systems that were controlled by feedback and for which this nomenclature applied. When you are dealing in difference equations, stability is determined by the magnitude of the gain, rather than by its sign. Hence, speaking of positive or negative feedback gains in this context is misleading and really inappropriate.

    [Response: You appear to be on a different plane from everyone else here. Please read the refernce I gave you before. You are still very confused. -gavin]

  29. 229

    I’d be interested to find out more about the programme’s comments on malaria and global warming – it seemed to be saying that climate change will not affect the range of malaria-carrying mosquitoes. Is anybody able to say more about this?

    Incidentally, check out
    for news of how 1987’s Montreal Protocol, designed to limit ozone-damaging chemicals, has also cut greenhouse gas emissions.

  30. 230
    Reid says:

    #224 BPL – No. He was making the argument that CO2 was self reinforcing both when the temperature was going up and when it was going down. I was making the point that it cannot do both for the same system state. In fact, if Marcus’ little example can be thought of as representative, it is self reinforcing only on the way down because this is a stable system, what most people in stability circles would refer to as a “negative feedback” system.

  31. 231
    tamino says:

    Re: #212 (tony)

    Dr. Sallie Baliunas, an astrophysicist with the Harvard-Smithsonian Center for Astrophysics and one of the nation’s leading experts on global climate change …

    I’m a mathematician, I worked for years doing time series analysis in astrophysics. I’m familiar with Dr. Baliunas, I’ve even referenced some of her work in my own publications.

    I sincerely want to know, where did hear that she is “one of the nation’s leading experts on global climate change”?

  32. 232
    Reid says:

    Gavin – don’t blame me for your poor nomenclature. If you explained things to any controls engineer in the world the way you explained them to me, they would immediately make the same leaps as I did, i.e., “positive feedback? you must either have a runaway condition or a limit cycle.” The term “positive feedback” is a very loaded and alarming phrase in controls circles. When you call it this, and it turns out to, in fact, be a stabilzing feedback, you are apt to get gross misinterpretations when you present to a larger audience.

    What you need to get your mind around is what I have stated. Feedbacks need to be classified on the basis of whether they are stabilizing or destabilizing. When you take a set of difference equations and talk about feedbacks as either positive or negative, but this has no bearing on whether they are stabilizing or destabilizing, you might as well be calling them “charm” and “strange” feedbacks. Only worse, because the lack of information conveyed by the latter terms is better than the misinformation conveyed by the former.

    [Response: Misinterpretation are easily cured by reading the references. Try it. – gavin]

  33. 233
    Richard S Courtney says:

    Dear All:

    I have scanned the above but not read it all. As one of those who is repeatedly (above) compared to a holocause denier I think you need to know that I very much enjoyed what I read: rarely have I laughed so much.

    Let us be clear. There is no evidence for man-made global warming; none, not any of any kind.

    The existence of global warming (GW) is not evidence of anthropogenic global warming (AGW) because warming of the Earth does not prove that human activity warmed it. At issue is whether human activity is or is not affecting the changes to the Earth’s temperature that have always happened naturally.

    Nothing is constant in nature: everything changes all the time. And the Earth must have warmed or cooled over the past 100 years if its temperature were not constant over the past 100 years.

    Two thousand years ago – in Roman times – the Earth was warmer than now. After that it was cooler than now throughout the Dark Ages. That cool period was followed by the so-called Medieval Warm Period when the Vikings farmed Greenland and an insect now constrained to the South of France inhabited York. Then the Earth cooled to the so-called Little Ice Age. The Earth has been warming out of the Little Ice Age for the 300 years since then. Around 1700, Londoners used to have “Ice Fairs” on the frozen Thames each year. The last Ice Fair was held in 1814, and the Thames has not frozen solid since.

    A claim that man-made global warming exists is merely an assertion: it is not evidence and it is not fact. And the assertion does not become evidence or fact by being voiced, written in words, or written in computer code. Furthermore, insults (e.g. comparison to holocaust deniers) directed at those who challenge the claim do not convert it into evidence either.

    The fact is that any warming that may have happened during the last 100 years is within natural climate variability that has occurred in the past. And that warming could be a completely natural recovery from the Little Ice Age that is similar to the recovery from the Dark Age cool period to the Medieval Warm Period.

    Furthermore, the history of the estimated warming of the Earth does not agree with an assertion that human emissions were responsible for the warming over the last 100 years. The estimates of the Earth’s average surface temperature (mean global temperature: MGT) all show warming from before 1900 to 1940, then cooling from 1940 to 1970 with a further period of warming after 1970.

    The estimates show that most of the warming occurred before 1940 but 80% of the emissions were after that. Indeed, the start of the cooling period coincided with the start of the major emissions. Advocates of man-made global warming excuse this problem by attributing
    (a) almost all the rise before 1940 to be an effect of the Sun,
    (b) the cooling from 1940 to 1970 to be an effect of human emissions of aerosols, and
    (c) the warming after 1970 to be mostly an effect of human emissions of greenhouse gases.
    Evidence is lacking for this convoluted story to excuse the disagreement of the emissions with the temperature history.

    And there are several good explanations for the variations in global temperature over time. For example, clouds reflect solar heat and a mere 2% increase to cloud cover would more than compensate for the maximum possible predicted warming due to a doubling of carbon dioxide in the air. Good records of cloud cover are very short because cloud cover is measured by satellites that were not launched until the mid 1980s. But it appears that cloudiness decreased markedly between the mid 1980s and late 1990s. Over that 15-year period, the Earth’s reflectivity decreased to the extent that if there were a constant solar irradiance then the reduced cloudiness provided an extra surface warming of 5 to 10 Watts/sq metre. This is a lot of warming. It is between two and four times the entire warming estimated to have been caused by the build-up of human-caused greenhouse gases in the atmosphere since the industrial revolution. (The UN’s Intergovernmental Panel on Climate Change says that since the industrial revolution, the build-up of human-caused greenhouse gases in the atmosphere has had a warming effect of only 2.4 W/sq metre). Why should cloud cover vary? Well, the Sun’s activity varies and this alters the flow into the air of cosmic particles that initiate cloud formation.

    But the fact that there is no evidence for AGW is not evidence that AGW is not happening. Simply, there is no evidence that AGW is happening, and there is no evidence that AGW is not happening, either.

    Do not forget that global temperature has not again reached the high that it did in the El Nino year of 1998. And please beware assertions from people (such as the hosts of this blog) who are making a good living from the global warming scare.

    All the best


  34. 234
    Hank Roberts says:

    She’s described that way at denial and Western Fuels PR sites — OISM, junkscience, GreeningEarth; Google will get you the list.

    She’s got quite a record for being wrong; one of the great papers in that regard:
    (link found here)
    is awfully hard to find, none of the denial sites feature it any longer. Guess why?

  35. 235
    Hank Roberts says:

    Reid, you’re confusing physics with biology.

    Do you have a lawn? Do you understand the effects of nitrogen fertilizer on the color of the grass?

    Try an experiment: Make a checkerboard of meter squares with string and pegs, say 6×6 if it’s that big, or something proportional.

    Get some 1:0:0 (all nitrogen, no phosphorous or potassium) lawn fertilizer./
    Mix it in water at 0.1x recommended, 1x recommended, and 10x recommended amount of nitrogen.

    Randomize application to a third of the squares with each amount.

    Result will be illustrative of how biological systems respond. 0.1x, not much change; 1x, much greener; 10x, yellow and/or dead.

    Oh, this may be better done as a gedankenexperimenet, if you value the place you live.

  36. 236
    Dan says:

    re: 232. Your apparent failure to understand the basic science involved is only matched by the gross disinformation you are spreading. The science behind global warming is unequivocable. The research is strong and published in peer-reviewed journals. To think anything less is disingenuous to say the least.

  37. 237
    tamino says:

    Re: #232 (Richard Courtney)

    All your mistakes and mischaracterizations are not evidence, and they do not become so by virtue of your posting them on a blog comment.

    Go to the Goddard Institute for Space Studies or Hadley Centre for Climate Change and look at the real data — not the lies you’ve been told by denialists.

    As for your very snide comment to “please beware assertions from people (such as the hosts of this blog) who are making a good living from the global warming scare,” you remind me of the episode of The Simpsons in which they visit a chimp researcher in Africa — loosely based on Jane Goodall — who is secretly forcing the chimps to work in a diamond mine. At one point Homer lies on the bed throwing diamonds over himself, saying “Woo-hoo! Look at me! I’m a scientist!”

  38. 238
    Ike Solem says:

    Dear Richard S Courtney,

    I think most climate scientists would be happy to see evidence that fossil-fueled global warming effects will be minimal, but all the evidence points in the other direction.

    The evidence is fairly clear, particularly in the polar regions (thinning sea ice, rising ocean temperatures) and at higher elevations, as climate models predicted. The changes in the hydrologic cycle as a result of the greenhouse gas induced-warming (i.e. the positive water vapor feedback effect) is also progressing as predicted.

    Generally speaking, if you make a theoretical prediction that is borne out by experimental or observational evidence, that means that the science behind the prediction is robust. Thus, thanks to climate modelers and satellite and ground observations, we can see that the climate is changing, and the explanation that fossil fuel CO2 is the cause is indeed well supported.

    We are also seeing the continuing slow rise of sea level, which may accelerate in the future due to the dynamic behavior of ice sheets, which don’t behave like static ice cubes, but rather which can flow at different speeds. We are also seeing some changes in ocean circulation. Thus, the conclusion is clear – the planet is warming, the climatic patterns are changing, and this is not a natural fluctuation, but rather the effect of burning large amounts of fossil fuels, particulary coal.

    You also say, “And please beware assertions from people (such as the hosts of this blog) who are making a good living from the global warming scare.” However, a quick check reveals that you yourself are a “Technical Editor for CoalTrans International (journal of the international coal trading industry)…. In the early 1990s Courtney was a Senior Material Scientist of the National Coal Board (also known as British Coal) and a Science and Technology spokesman of the British Association of Colliery Management.” From Sourcewatch

    Given that the single most important step in slowing global warming is ending the use of coal for energy on a global basis, shouldn’t readers be concerned that your position is not exactly that of the disinterested observer? On the other hand, you deserve commendation for using your real name, unlike others who post similar comments at RC.

  39. 239
    Mike Forster says:

    Many thanks to Gavin for the clarification.

    Gavin states:

    “All of the increase is anthropogenic. The last time CO2 was so high (i.e. 380ppm) could have been 3 million years ago (the Pliocene), but possibly not for 25 million years. However, estimates that far back are much more uncertain. Certainly farther back than 800,000 years. Given our understanding of the carbon cycle, it is extremely unlikely that there have been any ‘peaks’ up to 380ppm over that time”

    That said, is there ANY chance that at least some of the CO2 increase (i.e. from 280 – 380ppm over the last 150 years) is the result of the CO2 ‘lagging’ behind the Medieval warm period?? Based upon your surmisal above, there is either no correlation between warm periods and several-hundred-year-later-CO2 spikes OR there have been no other such warm periods during the last 800,000 years (at least if the ice core records are reliable). I find the latter very hard to believe…. so is the T/CO2 time lag thing all a load of bunkum??

    Gavin also states:

    “The impact is controlled by the climate sensitivity – generally given as the warming you expect from a doubling of CO2. This is around 3C from multiple lines of evidence. From 280 to 380 ppm would be expected to give 1.2 deg C, from 380 to 480 around 0.9 deg C – both at equilibrium. You need to add in the other forcings (CH4, O3, CFCs, N2O, aerosols, solar) and take into account of the ocean lag to see where we should be now. However, stabilisation at 480 is an extremely challenging task.”

    Are there currently anything like reliable models for the other forcings you refer to? There are an awful lot of variables there. As well as ‘positive’ (bad news) feedbacks, aren’t there conversely any ‘negative’ (good news) feedbacks which could factor in? I only ever see ‘positive’ feedback mentioned.

    Some other questions if I may:
    1. Could we drop the average global temperature by 1C if we painted ALL roofs white, or are such assertions in some of the popular media rubbish?!
    2. Has anyone given any thought to ameliorationg the effcts of AGW (if it is indeed happening) by deliberately and systematically putting tiny reflective (‘global dimming’) particles up into the atmosphere? Say with an engineered (degradable) lifetime? (i.e. particles working much like the aerosol-driven cooling of recent decades.)
    3. Is there much truth in the fact that the planet’s 1.5bn cattle put out way more greenhouse gases (CO4) than all forms of human transport (CO2) put together? Anyone have any hard data in this regard? If so, could we all do far more good by becoming vegetarian than abandoning driving and flying?
    4. The Swindle programme also referred to anthropogenic CO2 output as being insignificant when compared to decaying vegetation (16x more than human CO2 outsput) and even more insignificant compared to CO2 output from the sea. Any one have any data one way or the other? Did the programme simply ignore the recyclability (intrinsic balance between photosynthesis and respiration) of the former and the significant centuries lag associated with the latter? That said, I suppose if any of the aformentioned assertions as per the Swindle programme have any merit, then one still has to then ask why CO2 has gone up 36% this last 150 yrs!
    5. If the vast scale of the Earth’s regulatory systems make them commensurately slow (centuries/millenia) to react to ‘prodding’ (here anthropomorphic CO2 output), then why do some scientists postulate such doomsday scenarios in as little as 50-100 years (eg the Sunday Times mag article of 11th March by the journalist Mark Lynas)?? From Wikipedia: ‘If all glaciers and ice caps melt, the projected rise in sea level will be around 0.5 m. Melting of the Greenland ice sheet would produce 7.2 m of sea level rise, and melting of the Antarctic ice sheet would produce 61.1 m of sea level rise.’ To a layman like myself, its hard to envisage the melting of either the Greenland or Antarctic ice sheets taking anything other than hundreds if not a few thousand years to melt even with a 6C temperature rise. As such – and to me at least – the IPCC estimates of sea level rises of between 180 – 590mm seem to be ‘on the money’ as it were. Do other bloggers accord?
    6. Lastly; is there any hard evidence that recent warming is a) entirely or even largely due to observed rises in CO2 levels and is NOT at least partly due to other non-anthropogenic factors? Surely the Earth’s dynamic climate is massively intricate and liable to vary over decades, centuries and millenia REGARDLESS of anthropogenic factors: couldn’t much or even most of the observed warming have happened even if post-Industrial Revolution man hadn’t been around the last 150 years??

    Thanks again for the great site.


  40. 240
    Flightless Bird says:

    I have been posting on a general message board (hence the silly name here) and trying to explain what climatologists think and why, and why the program was misleading. One question that I’ve been asked, to which I can’t find an answer by googling, is how much CO2 is being produced by other means than volcanoes (3% or whatever) and anthropogenic sources (97%). Relatively how much CO2 is produced through respiration by all the living organisms? All I can find is the net carbon fluxes for the ocean and land. Thanks.

  41. 241
    David B. Benson says:

    Re #200: Reid — Yes, it is believed that the pulse of carbon dioxide being introduced into the climate system will eventually go away. The paper

    David Archer & Andrey Ganopolski
    A movable trigger: Fossil CO_2 and the onset of the next glaciation
    Geochemistry/Geophysics/Geosystems: AN ELECTRONIC JOURNAL OF THE EARTH SCIENCES

    considers the matter. Assuming antropogenic carbon can be limited to 1000 Gt (currently 300 Gt) then the climate system returns to normal in about 150,000 years.

    Regarding the role of carbon dioxide in the climate of the past, the so-called greenhouse gases are only one component of a system with many known (and probably some still unknown) interactions. For example, the greenhouse gas concentration changes only explain about half of the observed temperature change from LGM to the Holocene Thermal Optimum, about 6 K.

  42. 242
    Reid says:

    Hank – I’m not confusing anything. The response is nonlinear. I got that just fine. I deal with grossly nonlinear systems all the time.

    The system Marcus provided was very helpful. But, this is not a positive feedback system in the usual and logical sense of the phrase. It is stable to the equilibrium point. It does not help you raise the temperature, though the temperature can rise on its own for a finite interval, what we call a transient. However, the appropriate norm of the entire state always decreases in the absence of forcing. Once you take the forcing away, it immediately starts heading back to the equilibrium.

    That’s a good thing. If this little system is representative, it means the climate is not self-reinforcing and that perturbations in the form of exogenous inputs will be degained by the feedback loop. This does not mean that exogenous inputs cannot force a new and hotter equilibrium point to be established. It just means that, once these forcings are taken away, it will not keep on driving itself upwards. That was my concern. That was my source of doubt, as such a runaway or limit cycle should have occurred in the past and the lack of such an evident instability in the climate record would appear to contradict the thesis. Let me be clear: the AGW hypothesis remains viable, just not in this more virulent form based on the preceding assumptions. And, for me, that is a source of some comfort.

  43. 243
    John Pepper says:

    I would just like to put on record that from a layperson I think this site is an excellent resource and of great value. Like one of the contributers above I didn’t watch the programme because I thought I would just get far too annoyed (and not be able to argue back). Its great to be able to come on here and read the background to the science. On the back of this site I have complained to Channel 4 and also to Dominic Lawson in the UK paper the “Independent” who made some supportive comments both before and after the programme.

    As a scientist who graduated 20 years ago, I think the level of this site is just about right and I feel I can always find a link to a helpful article which can explain things too me.

    Keep up the good work!

  44. 244
    tamino says:

    1. Could we drop the average global temperature by 1C if we painted ALL roofs white, or are such assertions in some of the popular media rubbish?!

    I don’t know. But here’s a back-of-the-envelope calculation.

    Guess: 500,000,000 rooftops.
    Guess: average rooftop area 400 m^2. That’s 0.04% of the earth’s surface.
    Guess: painting it white would increase its albedo by 0.5
    Therefore painting them all white would increase planetary albedo by 0.0004 (actually a bit more, because they’re mostly in lower latitudes, but this is just back-of-the-envelope)
    Climate forcing due to increase of albedo by 0.0004: 0.14 watts per square meter (W/m^2)
    Temperature change (using sensitivity of 0.8 deg.C per W/m^2): around 0.1 deg.C

  45. 245
    tamino says:

    Re: #244

    Correction to the back-of-the-envelope calculation.

    Increasing the albedo of 0.04% of earth’s surface by 0.5 leads to net albedo increase of only 0.0002. So the temperature change would actually be closer to 0.05 deg.C

  46. 246
    Hank Roberts says:

    Reid — type “Venus” into the search box at the top of the page; I guess that’s what you were afraid was predicted. Not so.

    Meanwhile, I see something interesting happening in the WSJ’s business section:

    Treasury’s Paulson Suggests
    ‘Principles-Based’ Regulation
    March 13, 2007 1:01 p.m.

    “Treasury Secretary Henry Paulson said Tuesday that U.S. policy makers should consider adopting “principles-based” regulations and accounting standards, in part to keep pace with increasingly competitive global capital markets.
    (Read the text of the speech.)
    —- quote —-
    “We should assess how the current system works and where it can be improved…. And we should also consider whether it would be practically possible and beneficial to move toward a more principles-based regulatory system, as we see working in other parts of the world.

    “Our goal should be better managed, more competitive corporations that earn investor confidence through sound leadership, thoughtful governance, and outstanding performance. In my judgment, we must rise above a rules-based mindset that asks, “Is this legal?” and adopt a more principles-based approach that asks, “Is this right?”
    —– end quote——
    That should be reassuring to the coal companies, who, presumably also want to do what’s right — but right now fear they will be sued if they do anything reducing shareholder short term profit by admitting that changing the climate is an externalized cost of burning fossil fuel.

    Good news, for a change, eh?

    He also says, just after the above:

    “And we should consider whether our legal system appropriately protects investors or gives too much latitude to unscrupulous lawyers.”

  47. 247

    [[Let us be clear. There is no evidence for man-made global warming; none, not any of any kind. ]]

    99% of climatologists seem to disagree with you.

  48. 248
    Richard S Courtney says:

    Dear All:

    re postings 236, 237 and 238. I correctly and accurately said there is no evidence for man-made global warming; none, not any of any kind. The responses say there is some such evidence but cite no such evidence (which is not surprising because there is none). However, the responses do provide insults (as is usual from global warming fanatics).

    Nasty, nasty, nasty.

    Me, I prefer science not this anthropogenic global warming superstition.

    Now, would anybody like to comment on the facts that I cited pertaining to cloud cover? Oh, sorry, that was science so perhaps I raised it in the wrong place.


  49. 249
    Arne Melsom says:

    Living in Norway, I’ve taken the opportunity to look at the documentary on, I searched for “BBC Documentary The Great Global Warming Swindle” (I thought this wasn’t a BBC documentary -but it must be the right program).

    I discovered something interesting. At approximately 29:00 there is a curve that shows the solar activity vs. global temperature. And at about 33:25, there it is again, but now with global temperatures replaced by those in the Arctic. But wait! The latter shows the development until the end of the last century, while the former global time series ends at about 1980. I guess global temperatures are not yet available for the last 20 years… Surely, the viewers haven’t been swindled!?

    I haven’t read thru all the 200+ postings, so I realize that I may not be the first one to notice this.

  50. 250
    Dan says:

    re: 248. No, you do not understand the basics of the scientific process/method. You have preconceived ideas with no interest whatsoever in learning about the science. Until you do, your thoughts have no merit. When you can cite peer-reviewed articles to substaniate your views, people may take you seriously. Insulting people (“rarely have I laughed so much”) is the internet cry of the desparate and cornered. And insulting science and scientists when you do not understand it from the start will get you nowhere. Worse yet is pretending that you know the science. That is simply a sorry reflection on the state of science education.

    You can easily do a search on “cloud cover” and learn something right here on this site but you apparently, lazily choose not to. In other words, you are a drive-by poster, with no interest in learning about the unequivocable science (it is basic physics), what a consensus means, what peer-review is for, or the fact that virtually every major scientific organization across the world concerned with climate research agrees regarding the man-made influence of CO2 on global warming since about 1970.

    Your choosing 1998 as a “peak” year is simply disingenous since someone who understands science and climate would know that was an extreme El Nino year that simply added to the global warmth that year. If you knew basic statistics you would also know that one year does not make a trend.

    Insults to science and scientists as a whole such as “nasty, nasty, nasty” does nothing to support your position such as it is and simply sounds shrill. Not understanding and throwing out insults is nothing but desparate arrogance. Being accountable and being able to admit you are in error or wrong is a start in the right direction. The science simply does not support your opinions.

    Look at the data. Read the science. Learn from it. There is no excuse if the data and science do not agree with with you want it to say. And simply repeating something you think over and over with no science to support it does not make it any more accurate or truthful.