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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. 301
    Hank Roberts says:

    Speaking only as another reader here.

    It may not be you — the name has a track record online — and it’s not clear which Richard S. Courtney you are, whether you’re someone new using the same name or one of those who’s easy to find by searching climate postings.

    I trust our hosts check that postings under this name are coming from the same IP or a limited few, so nobody’s spoofing the name here to sow confusion (it happens, trolling is a sport).

    But, Google; several (apparently different) people using the name posted to a lot of climate sites, and there’s been a real effort to figure out why it’s so hard to know who RSC really is.

    Can you clarify who you are? are you the Oxford PhD? The academic in either of two American universities?

  2. 302
    Mike Forster says:

    I notice from links from what you folks here might call industry-driven disinformation websites that some Russian (particularly solar physicists) and Chinese scientists have very recently published articles in scientific journals (e.g. Chinese scientists Lin Zhen-Shan & Sun Xian in Meteorol Atmos Phys 95, 115-121 (2007)) claiming that global COOLING will occur in the early and middle of the 21st Century….. Is it a mistruth that such articles ARE being published in SJs? If not, then do the articles themselves merely comprise misinformation of little or no merit?

  3. 303
    Julian Flood says:

    Re 271/281

    When carbon is fractionated by a biological process, the heavier isotopes are both effected — C14 more so than 13 because it’s even less user friendly. So it might be able to differentiate my process out by checking change of C14/13 ratio. Unfortunately, I doubt if the accuracy is up to it yet. So the signal seen is a drop in the C13/C12 ratio and C12/C14.

    C14 in hydrates — just how old are the clathrate deposits, does anyone know?


  4. 304
    angus says:

    Thanks tamino for your support. I really do think you should update Prof Severinghaus’s piece about the lag. It is vague to say the least and is the first place I hit when googling for information.
    Is it a problem to say that in the past CO2 levels lagged temperature rise in a natural cycle? The real problem lies in injecting a massive amount of carbon when we are at the top of that cycle.

  5. 305
    Hank Roberts says:

    “… combustion products of environmental concern include nitrous oxides, sulfur dioxide, soot, and polycyclic aromatic hydrocarbons (PAH). Several of these species (such as sulfur dioxide and soot) may also play an important role in climate change, while others (such as PAH) impact environmental quality through their toxicological properties.

    “It is important, therefore, to distinguish and quantify emissions from different combustion processes. Developing temporal records that document amounts and sources of combustion products will help us assess past and present emissions and predict future trends. …

    “…. Carbon 14 abundances of the PAH are expressed in terms of “fraction modern”, where a value of 1 is equivalent to 100 percent modern carbon, and 0 corresponds to 100 percent fossil carbon. Carbon 14 measurements on pyrogenic PAH yielded a fraction modern value of about 0.9 in the early 1800s, and decreased to about 0.5 in the mid-1900s. This trend is consistent with increasing utilization of fossil fuels over this time period. … the fraction modern value for the pyrogenic PAH in the uppermost portion of the core (circa 1950) is surprisingly high. This interval coincided with the maximum utilization of coal as an energy source, after which oil and gas became the preferred fuels.”

  6. 306
    tamino says:

    Re: #302 (Mike Forster)

    … Is it a mistruth that such articles ARE being published in SJs? If not, then do the articles themselves merely comprise misinformation of little or no merit?

    These articles (at least the one by Lin Zhen-Shan & Sun Xian) are indeed published in scientific journals. Take note, this belies the claim that dissenting views are shut out of scientific journals.

    Scientific journals do not select what gets published based on whether or not the paper agrees with the concensus view. They are selected based on whether or not they conform to proper methodology and accurate data. For some of the biggest journals, there are so many papers submitted that they must be very selective, so non-concensus views are less represented than in other journals — but if your paper has proper methodology and correct data, you can almost always find a journal to publish it, no matter how far outside the concensus your viewpoint may be.

    I’ve seen the paper by Lin Zhen-Shan & Sun Xian, and it my opinion it is without merit. Their paper isn’t about physics or climate science, but about a mathematical analysis of temperature time series. In my opinion (and this is my field) they apply a rather dicey technique, and then use it to extrapolate into the future in a way which is not justified by either the data or the mathematics.

    But again, scientific journals aren’t about choosing based on the concensus view or limiting papers to what is universally accepted; they’re about presenting a number of different viewpoints so that readers can decide for themselves what has merit and what doesn’t.

  7. 307
    Hank Roberts says:

    > how old are the clathrate deposits?

    I asked the same question a while back; there’s a deeper question (how old is the methane _in_ the clathrates) because the clathrates may be a transition material produced as methane moves _up_ from deep and very old sources, and interacts with cold water in seafloor sediments.

    Look for geological info on “pingo” structures, which the gas industry is already talking about mining for methane. The geologists up til a few years ago said they were caused by freezing of ice under sediment, but now they’re popping up — er, being found — whichever — in shallow ocean along the continental shelf.

    I hope an expert here will comment on what’s being found out — are pingos recent, caused at the end of the ice age by the peak warming, perhaps? If so we may be provoking a new round of them by keeping temperature from declining after the last peak 10-11,000 years ago.

    One tangentially helpful cite:
    The biogeochemical consequences of the mid-Cretaceous superplume

    Jahren A., Department of Earth and Planetary Sciences, Johns Hopkins University

    This journal article (published in the Journal of Geodynamics) proposes that large amounts of carbon were liberated from submarine methane clathrate deposits during the mid-Cretaceous superplume event.

    Evidence for this hypothesis is based on carbon isotope records of marine carbonates, marine organisms, and terrestrial plants.

    The author speculates that possible effects of this disruption on the global carbon cycle may have included widespread oceanic anoxia and changes in land plants at mid- to high-latitudes.

  8. 308
    David B. Benson says:

    Re #293: Mike Forster — In a simple, orbital forcing theory way, more than 100% of the current warming is anthropogenic. According to orbital forcing, the golobal temperature should be in a very gentle decrease ever since 8000 years ago, leading to an attempt at a stade (big ice sheets) in about another 20,000 years.

  9. 309
    ramalama says:

    someone wrote:

    “Explanations of the lag aren’t the weakest part of the case: they aren’t part of the case at all. The case for AGW doesn’t depend on records of past climate changes; it comes from the known behavior of CO2, and the indisputable (except by blithering idiots) fact that humans have put a lot of it in the atmosphere over the last century or so.

    At its most basic, AGW theory is no more complicated than saying you’ll be warmer if you put a sweater on, and that doesn’t depend on what your granny told you, does it?”

    Gosh, NOW I get it!!!

    [rest edited out….we probably shouldn’t have let this first comment through w/out editing, but that’s no excuse for fanning the flame war. Folks, if you can’t be civil, your posts won’t make it through]

  10. 310
    Sean Ferguson says:

    My first impression after having watched both ‘An Inconvenient Truth’ and the channel 4 GGWS is that climatology seems to lack the sort of experimental modalities and valid, reliable criteria for discerning causal relationships that some other fields have obtained – say microbiology with its Koch’s Postulates.

    Statistical significance is all well and good, but meaningless if your experimental design doesn’t equip you to identify a casual relationship. What is climatology’s equivalent to the RCT? If there is none, isn’t the positive feedback loop argument to explain away the time lag between temperature rise and CO2 rise just more conjecture about causation? In fact, doesn’t the feedback argument presuppose that CO2 rise was what caused the temperature rise in the first place? That being the case, the parsimonious (even if incorrect) explanation for the time lag seems to be something akin to what Carl Wunsch himself proffers in the GGWS documentary.

    Please answer if you’re equipped to discuss experimental design. Thanks.

  11. 311
    James says:

    Re #295: [I have looked for comments regarding the experiment last Year in which Prof Henrik Svensmark successfully generated cloud condensation nuclei by bombarding a replica atmosphere with ionising radiation. Why does it appear that this is being ignored by everyone?]

    In addition to the other responses, because it’s rather old news. The same principle is used in cloud chambers, which have been around for more than a century. See here:

    If you’re really interested, there’s a link or two from there that give instructions on how to build your own.

  12. 312
    Mike Forster says:

    I’ve just seen/read the transcript from the BBC Horizon programme of January 2005 about ‘Global Dimming’.

    It does NOT make for reassuring reading.

    I’d accordingly be interested to hear what any of you AGW denialists out there have to say about the surmisals made as per the abovementioned piece…….

    What’s the current opinion within the wider scientific community as regards just how bad AGW could get if we clean up pollution particles WITHOUT at the same time drastically lowering anthropogenic CO2 emissions? One assertion in the programme was that temperatures could go up by as much as 10C by 2100 IF global dimming is eliminated and anthropogenic CO2 amissions not drastically cut…… Is this view still currently shared by many respected climatologists? Or has new evidence emerged that significantly changes the scenario?

    As an aside, are there any estimates out there as to how long the Greenland ice sheet would take to melt if temperatures increased by 5-10C by 2100?

  13. 313
    Joe Rosenfels says:

    Left field: Methans quote: “Methane in the Earth’s atmosphere is an important greenhouse gas with a global warming potential of 23 over a 100 year period. This means that a 1 tonne methane emission will have 23 times the impact on temperature of a 1 tonne carbon dioxide emission during the following 100 years”

    The focus should be to reduce methane and worry less about c02, but that would not be politically correct?

  14. 314
    tamino says:

    Re: #309 (Joe Rosenfels)

    The same wikipedia article you reference also states that the atmosphere contains 220 times as much CO2 as methane. So the total climate forcing from CO2 is greater than that from methane (as is well documented in the IPCC reports).

    But methane is the 2nd-most potent antrhopogenic greenhouse gas (after CO2), as is alwo well documented in the IPCC reports, and is a subject of great concern.

    I fail to see why reducing methane would not be “politically correct.”

  15. 315
    Hank Roberts says:

    >309, Joe Rosenfels

    Hey, Joe — guess who you agree with about that?

    ” … absolute reduction of the principal non-CO2agents of global warming, particularly emissions of methane gas. Such methane emissions are not only the second-largest human contribution to climate change but also the main cause of an increase in ozoneâ��the third-largest human-produced greenhouse gasâ��in the troposphere, the lowest part of the Earth’s atmosphere. Practical methods can be used to reduce human sources of methane emission, for example, at coal mines, landfills, and waste management facilities. …

    “If both the slowdown in CO2 emissions and reductions in non-CO2 emissions called for by the alternative scenario are achieved, release of “frozen methane” should be moderate, judging from prior interglacial periods that were warmer than today by one or two degrees Fahrenheit.”

  16. 316
    Ike Solem says:

    Richard, you say that “the carbon-14 change is far too great for it to be explained by the anthropogenic emission.” without giving any references or supporting information.

    The CO2 carbon 14 issue was addressed some 50 years ago: see the excellent online guide to the history of the science at :

    “Fortunately, scientists could now track the movements of carbon with a new tool – the radioactive isotope carbon-14. This isotope is created by cosmic rays in the upper atmosphere and then decays over millennia. The carbon in ancient coal and oil is so old that it entirely lacks the radioactive isotope. In 1955, the chemist Hans Suess reported that he had detected this fossil carbon in the atmosphere.

    The amount that Suess measured in the atmosphere was barely one percent, a fraction so low that he concluded that the oceans were indeed taking up most of the carbon that came from burning fossil fuels. A decade would pass before he reported more accurate studies, which showed a far higher fraction of fossil carbon. Yet already in 1955 it was evident that Suess’s data were preliminary and insecure. The important thing he had demonstrated was that fossil carbon really was showing up in the atmosphere.”

    The real issue is how the oceans will respond to warming, and whether they’ll continue to take up as much CO2 as in the past.

    RE#309, it’s the abundance of CO2, and the fact that methane in the atmosphere gets converted to CO2 over time (sunlight + methane + oxygen (OH-, etc) -> CO, CO2). The problem is the use of fossil fuels, which are ancient carbon – cows and other methane-producing ruminants are very different in that their carbon source is plant photosynthesis, not buried deposits; thus is you measure methane coming out of cows (some job that would be..) you’d find that it has an identical C-14 content to the atmosphere, while fossil methane deposits (natural gas) are completely depleted in C-14. Still, producing methane instead of CO2 increases the radiative forcing; but the 4th IPCC summary states that the forcing due to anthropogenic methane is about 1/4 that due to anthropogenic CO2. Atmospheric methane has also apparently (temporarily?) stabilized over the past few years, unlike CO2:

  17. 317
    Dave Rado says:

    1) There is approximately 220 times as much CO2 in the Earth’s atmosphere as methane.

    2) CO2 remains in the atmosphere on average for around 200 years, whereas methane remains in the atmosphere on average for around 10 years; so methane’s *overall* greenhouse effect over the cycle is not much higher than that of CO2.

    3) We are not currently releasing methane into the atmosphere at anything like the rate that we are releasing CO2 into the atmosphere – in fact there is no currently significant trend in atmospheric methane levels, which means it is not currently contributing anything at all to global warming.

    4) On the other hand, there is a very real danger than permafrost melting resulting from global warming, see:
    … may well eventually cause methane to rise at a sufficiently fast rate to cause a chain reaction, where global warming causes methane to be released, which causes more warming, which causes more methane to be released, and so on, until it gets out of control and the temperature starts to soar. This could then trigger a second chain reaction, because when the temperature reaches a certain level, methane trapped in ice-like structures called clathrates at the bottom of the oceans could start to be released rapidly into the atmosphere. There is 3,000 times as much methane trapped in clathrates as there is in the atmosphere.

    There is very strong evidence that this has happened before – see:–neo102003.php

    So in other words, methane is not currently contributing to global warming; but if we don’t start to reduce our CO2 emissions soon, there is a genuine risk that methane may start to contribute to global warming in the future; and if that does happen, it would probably be extremely serious, to the extent that the highest end climate projections could start to look plausible.

    See also:

  18. 318
    Gareth says:

    …measure methane coming out of cows (some job that would be…)

    We do that all the time down here (NZ). Here’s a picture of some sheep wearing methane measurement gear. I’ve had a chat with methane measurers – apparently, you can detect the methane plume from a dairy farm miles downwind.

    Suggestions that cutting methane emissions is a quick and “easy” way to reduce forcing don’t work for us, where half of our emissions are from agriculture. Probably not easy if you grow a lot of rice, either.

  19. 319
    john graves says:

    Well then. 318 comments in just five days.Certainly stirred up the hornets nest then, didn’t we?

  20. 320
    P. Lewis says:

    Re: #294 (tamino)
    Hi Tamino

    I genuinely admire the outwardly serene way you can answer what I see as a lot of plain ignorance, misunderstanding and outright distortion. It is a gift. Keep up it up.

    Now it might be a personality disorder, but I ain’t made like that, I’m sorry. Up to a point, I can be as amiable and helpful (and as serene) as you in replies to anyone who shows genuine interest (and I don’t mind if it’s a contrary point of view to mine to argue; indeed, here and elsewhere I’ve stood up for contrarians when ad hominems have been visited io). But Angus’s point (misunderstanding?) has been covered ad nauseum amongst the replies already on this thread (and elsewhere recently), and it is covered and referenced in the OP and accessed easily through the FAQ.

    I suppose it’s how the question is asked, or perceived as being asked. To my mind, there’s a way of asking questions if you would like things explained more clearly. I didn’t (and still don’t) see that in Angus’s first two messages.

    With regard to my reply to Angus and surmising that he was taking a contrarian view. Far from it. There was sufficient evidence in his #274 post to form the view that Angus did not take that position. It was penned purposely with the intent of conveying disbelief that Angus could entertain that all the professional climate scientists have overlooked this issue (and yes, I know, they’re not all-knowing gods who must be obeyed without question; and that not even the great GS himself gets it right all the time) and that CO2 lag was not an issue. I can take the distortion and misunderstanding, but there is a pervading arrogance abroad that a poster knows more than the professionals whose job climate study is (you see a similar situation on physics discussion boards in relation to attacks on Einstein’s relativity theories: “everyone” has spotted the errors of Einstein). I find it infuriating, on their behalf.

    Re: #304 (Angus)
    But, in #304, I sense Angus’s tone is more correct (to my sensibilities, anyway):

    Is it a problem to say that in the past CO2 levels lagged temperature rise in a natural cycle?

    to which, Angus, once again (but less sarcastically), I would reply “no”:

    Anti-AGW lobby: “CO2 lags. Wow, that’ll shoot that there pro-AGW lobby down in flames! Let’s see ’em get out of that one.”
    Pro-AGW lobby: “CO2 lags. Yes, we know. So what! It’s factored in to our understanding.”

    The lag out of ice ages is really a non-issue wrt to 21st century AGW, and it’s not an issue palaeoclimate-wise (which is not to say that there isn’t science in looking at that lag, or at other aspects of the forcing that led to ice waxing and waning).

    Oh, and Angus, Prof. Severinghaus is not part of RC so far as I can see. He either offered to or was asked to contribute a piece with regard to his group’s peer-reviewed work in gas analysis in ice cores and its application to palaeoclimate studies. Presumably, that study and others of its ilk are/will be contained somewhere within the body of the IPCC AR4.

    To Angus, try to re-read the RC article if you can and read Caillon, Severinghaus, et al. (2003): Timing of atmospheric CO2 and Antarctic temperature changes across Termination III. Science 299: 1728-1731, on which the RC article was based. And then read this (fairly typical) distortion, this time by the Association of British Drivers:

    The most recent study available covering this theme is that of Caillon et al. (2003), who focused on an isotope of argon (40Ar) that can be taken as a climate proxy, thus providing constraints about the relative timing of CO2 shifts and climate change. Air bubbles in the Vostok ice core over the period that comprises what is called Glacial Termination III – which occurred 240,000 years BP – were studied. The result of their painstaking analysis was that “the CO2 increase lagged behind Antarctic deglacial warming by 800 +/- 200 years.” This finding, in the words of Caillon et al., confirms that CO2 is not the forcing that drives the climatic system. Anthropogenic climate change (man-made global warming theory), based on the claimed impact of CO2 emissions from transport and industry, is stone cold dead.

    and then spot what Caillon et al. did say and didn’t say.

  21. 321
    P. Lewis says:

    Re #320

    Oops! Hit the “Post” button by mistake. Duh!

    “io” was meant to have been “upon them”.

    And “Oh, and Angus, Prof. Severinghaus” was meant to have read “Oh, and Angus, if you were wondering (and someone was), Prof. Severinghaus”.

    Sorry folks (need a recall button).

  22. 322
    Joe Rosenfels says:

    Perhaps we should power our cars with methane?

    One more question when reviewing global temperatures, on a year to year basis, temperatures do not increase some years they actual decrease:
    This I find interesting as c02 only ever increases:

    Any comments, cheers.

  23. 323
    W Low says:

    I’ve read in various places on the Internet that CO2 was 4400ppm during the Ordovician period. If that is true, people must wonder whether the Earth was 12 times as warm as well, and, if not, then why wasn’t temperature in step with CO2. The implication one may derive is that temp isn’t (always) in step with CO2 so why can’t the world at least wait till it reaches that amount before we get worried. This is the only Global Warming “controversy” issue that I have not seen addressed here of which I am aware.

  24. 324
    dhogaza says:

    One more question when reviewing global temperatures, on a year to year basis, temperatures do not increase some years they actual decrease:
    This I find interesting as c02 only ever increases:

    Well, quite clearly, as the climate scientists here and elsewhere patiently point out over and over again, CO2 isn’t the only thing out there that impacts temperature.

    You can google this site, you know? Learn before you post, etc etc?

  25. 325
    Angus says:

    All I have been trying to say is that you guys should put up a cogent explanation (ie understood by non-climatologists) as to why the historical record is not relevant to AGW. The dissenters will just keep pointing to the lag and say CO2 is not responsible for our present predicament, Mr Gore’s presentation of the ice core data in his movie opened a door for channel 4, I like may others wanted to know the truth on this point, Prof Severinghaus’s piece does not do the job.
    Here would be my interpretation (forgive a non climatologist)
    1) Ice ages finish when the solar energy impinging on the earth causes temperatures to start to rise.
    2) Over a period of time CO2 is released into the atmosphere, peaking about 800 years later.
    3) As the solar energy falls the CO2 greenhouse effect acts to compensate this and a complex feedback effect causes the temperature to oscillate back down to the previous levels.
    4) This natural process has been endangered by injecting vast amounts of carbon at the top of the cycle.

  26. 326
    Timmothy K. says:

    Via Carl Wunsch’s Climate Change site @

    People ask “is it clear that human activity is directly responsible for climate change?” The context for answering this question must be another question: to what extent can the climate change all by itself?

    The answer to the alternative question is: “a very great deal.”

  27. 327
    BarbieDoll Moment says:

    RE: …”As an aside, are there any estimates out there as to how long the Greenland ice sheet would take to melt if temperatures increased by 5-10C by 2100? “…

    Here are two actual current assessments of the sheet which
    one could possibly work with to derive some type of idea
    that it doesn’t require that type of temperature change
    for the sheets to significantly melt, and in turn,
    raise water levels.

    Rapid volume loss from two East Greenland outlet glaciers quantified using repeat stereo satellite imagery
    Geophysical Research Letters 34 (5), 05503 (2007)
    “The coastal portions of Kangerdlugssuaq and Helheim glaciers in southeast Greenland lost at least 51 ± 8 km3 yr^-1 of ice between 2001-2006 due to thinning and retreat, according to an analysis of sequential digital elevation models (DEMs) derived from stereo ASTER satellite imagery.”…”Extrapolation of the measured data to the ice divides yields an estimated combined catchment volume loss of ~122 ± 30 km3 yr^-1, which accounts for half the total mass loss from the ice sheet reported in recent studies. These catchment-wide volume losses contributed ~0.31 ± 0.07 mm yr^-1 to global sea level rise over the 5-year observation period with the coastal regions alone contributing at least 0.1 ± 0.02 mm yr^-1.

    The 1979-2005 Greenland ice sheet melt extent from passive microwave data using an improved version of the melt retrieval XPGR algorithm
    Geophysical Research Letters 34 (5), 05502 (2007)
    “Analysis of passive microwave satellite observations over the Greenland ice sheet reveals a significant increase in surface melt over the period 1979-2005. Since 1979, the total melt area was found to have increased by +1.22 x 10^7 km2.”…“Finally, the observed melt acceleration over the Greenland ice sheet is highly correlated with both Greenland and global warming suggesting a continuing surface melt increase in the future.

  28. 328
    Leo says:

    I have to agree with Angus (#325) that the illuminated amongst you are doing the rest of us no favours in trying to get a grip on this.

    If CO2 is causing most of the global warming, we need to be told how that has been shown in clear, unambiguous terms.

    What hard data shows that CO2 increases T rather than the other way round?

    Why do some of you dismiss the lag between T and CO2 as irrelevant?

    Where are the analyses of the ice-core data that Durkin used?

    Why are they wrong?

    I’ve been following this thread since it started and am now frankly more confused than when I started. Perhaps a week isn’t long enough to get one’s head round all this from scratch, but please guys, give us a fighting chance.

  29. 329
    Angus says:

    Now Leo, you are only going to set them off again! CO2 is a greenhouse gas- proven, its forcing effect depends how much of it is the atmosphere, historically it appears it was insufficent to cause a problem, a natural feedback cycle occurred and temperatures oscillated but came back to “normal”.In a geological heartbeat we have increased that amount by a very large percentage, history no longer applies.

  30. 330
    Dave Rado says:


    If CO2 is causing most of the global warming, we need to be told how that has been shown in clear, unambiguous terms

    In science, the way things work and have always worked is: you start with some evidence, you then come up with a theory to explain that evidence, you then test that theory using real world observations and make sure it fully explains *all* observations and that no observations fatally contradict the theory; and if any does, you modify the theory where needed. In the case of the greenhouse effect, the evidence and theory for that is more than 150 years old:
    and has been tested by millions of real world observations without any evidence contracting the theory, so is as solid as Newton’s laws are.

    In terms of testing the evidence against the theory, I can’t list here all of the millions of strands of evidence that all corroborate the theory but there *are* literally millions of strands, and there are none that contradict it. The proof of how incredibly well the theory matches up with the real observed evidence is here:
    and here:

    What hard data shows that CO2 increases T rather than the other way round?

    It’s not “rather than the other way round”. It works *both ways* round. The fact that increasing the number of chickens in a coup leads to an eventual increase in the number of eggs is not evidence that increasing the number of eggs wouldn’t also lead to an eventual increase in the number of chickens.

    CO2 in the atmosphere doesn’t just spontaneously increase without any cause: in the past it increased very slowly (over many hundreds of years) due to warming triggered initially by changes in the earth’s orbital tilt:
    The CO2 that had been added to the atmosphere then caused warming of its own, which greatly amplified the warming that had already taken place; and as a result the overall amount of warming was much higher and lasted far longer than would have been the case without the influence of CO2. Without the greenhouse effect, the warming would have lasted for a far shorter time and been far less.

    Why do some of you dismiss the lag between T and CO2 as irrelevant?

    It is irrelevant to what is going on now, which is that we have now artificially increased CO2 levels by more than 30% in only 150 years, with even more rapid rises likely during this century. This is something that has never happened before in the earth’s history. And it is also irrelevant in the sense that no climatologist has ever claimed that the ice core data is important evidence for global warming theory. Durkin was using a straw man argument:
    … by pretending that the ice core data was important to global warming theory, when it is not.

    Where are the analyses of the ice-core data that Durkin used?

    Why are they wrong?

    They are not wrong about what the ice core data *is* but they are completely wrong about what it *implies* – see explanations above. And please *read* the articles I linked to before replying.

    Durkin and co. are perfectly well aware of all the above, it isn’t at all controversial in scientific circles, which is what annoys so many of us here. It is highly unethical to knowingly use fallacious arguments on a scientific subject, and especially on a subject as important as this one is, that they know perfectly well are fallacious, in order to mislead people. I can’t say any more about that aspect of it here because this is a scientific forum and it is not an appropriate place to discuss what might be motivating these people.

  31. 331
    Dave Rado says:

    Re. #326 you’re misundersatanding what Carl wrote. He does not mean “to what extent do natural cycles influence climate”, which seems to be what you think he meant. The natural influences are fully taken into account in all the climate models, see:

    He means “to what extent does the climate simply change for no reason whatsoever, in the process disobeying all the laws of physics”; and the answer to that question is that it doesn’t.

  32. 332
    Leo says:

    OK, so I’ve just looked again at Caillon et al

    (which is Durkin’s source for the lag data – sorry for not clocking that above)

    and I see that

    “The radiative forcing due to CO2 may serve
    as an amplifier of initial orbital forcing, which is
    then further amplified by fast atmospheric feedbacks
    (39) that are also at work for the presentday
    and future climate.”

    (Which, if I understand it correctly means an initial temperature rise may cause a realease of CO2 after a lag of 800 years, which may lead to further warming)

    But has anyone actually shown this to be the case?

  33. 333

    [[Left field: Methans quote: “Methane in the Earth’s atmosphere is an important greenhouse gas with a global warming potential of 23 over a 100 year period. This means that a 1 tonne methane emission will have 23 times the impact on temperature of a 1 tonne carbon dioxide emission during the following 100 years”
    The focus should be to reduce methane and worry less about c02, but that would not be politically correct? ]]

    Your assignment for tomorrow: Look up a table of the constituents of Earth’s atmosphere. Find the mean molecular weight of air and the molecular weights of carbon dioxide and methane. Find the mass fraction of each and the total airborne mass of each. Compare and contrast.

    Here’s a hint to get you started: The total mass of Earth’s atmosphere is about 5.136 x 10^18 kilograms.

  34. 334
    Dave Rado says:

    Re. #322, as people have pointed out over and over again in this thread, there are many influences on climate; and many more influences on weather; than CO2 alone. Year on year changes are *weather*, *not* climate. E.g. La Nina/El Nino. *Please* read up about them before posting back.

  35. 335

    [[One more question when reviewing global temperatures, on a year to year basis, temperatures do not increase some years they actual decrease: This I find interesting as c02 only ever increases: ]]

    CO2 is not the only thing that affects climate or Earth’s temperature. It is also affected by other greenhouse gases, changes in solar luminosity, cloud cover, aerosols, and orbital changes. Nobody said it was a one to one relationship. What they did say is that, other things being equal, more CO2 yields a hotter ground.

  36. 336

    [[What hard data shows that CO2 increases T rather than the other way round?]]

    John Tyndall demonstrated in 1859 that CO2 absorbs infrared light.

    All objects, unless they are at absolute zero temperature, radiate photons in an amount proportionate to the fourth power of their temperature.

    Sunlight heats the ground. The ground radiates infrared. Carbon dioxide (and water vapor, etc.) absorb the infrared. The greenhouse gases heat up. They radiate infrared themselves. Some of the infrared goes back to the ground.

    The ground is getting both sunshine and “atmosphere shine.” Increasing CO2 increases the IR coming from the atmosphere, and heats the ground more than it was heated before.

  37. 337

    [[Why do some of you dismiss the lag between T and CO2 as irrelevant?]]

    Because it describes natural climate variations, and we know the present surge in CO2 is not natural.

  38. 338
    Leo says:

    Thanks Dave (330)

    as you’ll have gathered I posted 332 before your response came up.

    I’ll go away and digest what you’ve written.

  39. 339
    Leo says:

    thanks for the theory but I was hoping for observation of this in action on an appropriate scale over time

  40. 340
    Angus says:

    From the last few posts I take it that my summary in 325 is correct and I can expain to the locals in my pub why the documentary thay have all been talking about was rubbish. Thank you gentlemen, for helping me to understand this particular point. To win this argument, you do need to win the man in the pub

  41. 341
    Dave Rado says:

    Re. #32 and taking into accoutn #338; in addition to what I posted in #330:

    (Which, if I understand it correctly means an initial temperature rise may cause a realease of CO2 after a lag of 800 years, which may lead to further warming)

    But has anyone actually shown this to be the case?

    1) Given that the greenhouse effect is as well established physics as Newton’s laws are, if it were not the case, then you would have to somehow explain why the greenhouse effect mysteriously failed to operate during those thousands of years. No-one has ever tried to explain that, and Durkin simply ignored it.

    2) The amount of warming that took place and the lenghth of the warming that took place is impossible to explain unless you take the greenhouse effect into account.

    3) If the warming had been caused by orbital fluctuations and ice melting alone, the tropics would have warmed far less quickly relative to the Arctic than they did.

  42. 342
    Andy Mitchell says:

    Carl Wunsch should make his complaints to the ITC. Martin Durkin has previously made ‘Against Nature’ which was found by the ITC to have ‘distorted or misrepresented’ contributions. Channel 4 was forced to make an apology in primetime.

  43. 343
    tamino says:

    Re: Angus and Leo

    Come on, everybody! Angus and Leo have expressed skepticism (not denial) based on the propaganda they’ve been fed, and that’s entirely natural. But instead of just accepting it at face value, they’ve come to RealClimate (which so many of us tout as the best climate-science blog on the net) to get answers. They’ve asked questions, and the answers don’t satisfy, so they ask more questions. Frankly I admire their willingness to look deeper than the surface.

    So instead of just retorting with a snarky, “Do your homework first,” we should be giving them the best answers of which we’re capable. After all, these are exactly the people we’re trying to persuade: the man (or woman) in the pub. And, as much as we may consider ourselves to be graced with more thorough knowledge, it’s the man & woman in the pub who will go to the voting booth and choose the leaders who have the power to do something about it.

    If our answers have failed to persuade them, the fault, good Horatio, lies not in our stars, but in ourselves.

    To Angus and Leo: I’ll try to answer your questions as best I’m able. But right now I have to go to the airport for a long trip, so I’m not sure when I’ll be able to get to it. But if you’ll be patient, without losing your interest or your skepticism, then if nobody else answers adequately, I’ll be back. Soon.

  44. 344
    Angus says:

    Thanks again tamino, have a safe trip. I for one am now convinced. CO2 is a greenhouse gas that is released when the earth warmed, there was complex feedback mechanism that caused the temperature to oscillate back down to “normal” levels when external energy was removed. The mass of C02 released would effect the length and periodicty of this feedback. The rate at which we have pumped CO2 into the atmosphere over the last century means that this model no longer applies.
    This probably over simplistic, but before I get flamed again, please consider tamino’s comments, suffer us fools with good humour rather than contempt.

  45. 345
    Hank Roberts says:

    Well said, Tamino.
    It is true that new people ask FAQs here over and over; while there are many pointers and the search tool, the actual FAQs do take some basic reading, the sidebar links are helpful in that.

    It ain’t rocket science — it’s harder.

  46. 346
    P. Lewis says:

    Re #328 (Leo)

    If CO2 is causing most of the global warming, we need to be told how that has been shown in clear, unambiguous terms.

    CO2 is not doing most of the global warming. That is the prerogative of Sol and H2O. Pumping fossil-carbon CO2 into the atmosphere is a prime factor in anthropogenically enhanced global warming (AGW). There are “two processes”: natural and AGW.

    What hard data shows that CO2 increases T rather than the other way round?

    There are misconceptions here.

    Temperature increases enable the release of locked-in CO2 (e.g. from ocean degassing). CO2 can follow temperature up (e.g. out of an ice age) and down (e.g. in to an ice age).

    But the classical and quantum physics of IR absorption (and experimental work) show that CO2 traps heat (causing the temperature to rise); more CO2, more heat trapped; temperature goes up. Temperature can follow CO2.

    The effects work independently and in concert. It’s a feedback/forcing. It doesn’t matter which comes first, the chicken or the egg. It is that simple (except that it is not that simple, because you have various other positive factors; and you have negative feedbacks trying to counter the rise in temperature, e.g. aerosols). So far as I’m aware, there hasn’t been a peer-reviewed publication discounting this basic physics of CO2 absorption of IR (since the QM work was done with regard to band shapes in the mid to late 50s(?)). It’s literally textbook stuff (I’m sure someone can recommend one if you ask.).

    Why do some of you dismiss the lag between T and CO2 as irrelevant?

    The lag is not strictly irrelevant (physically); if the CO2 wasn’t released in time and in sufficient quantities before the Earth’s various wobbles and/or solar output start to decline again, then it wouldn’t be irrelevant. And if you’re discussing palaeoclimate then it is relevant to what’s going on. The lag is irrelevant in the context of AGW (for the reasons already indicated).

  47. 347
    Angus says:

    Dear Mr Whitney
    I was initially impressed by this documentary and resolved to find the truth for myself. I have spent about a week here and read a lot of science, not pseudo science. It’s heavy going but I would suggest you do the same, if you have a open mind you may be be surprised.

  48. 348
    Bob says:

    Seems to me that if we can causing warming with CO2 and cooling with sulphates, we should be able to set just about any temperature we want.

  49. 349
    Michael says:

    Bob (348)

    Our technology does allow us to alter the landscape to our choosing, but if nothing else, the science and research put into understanding the ecosystem has, if nothing else, taught us that the Earth is a fairly wise system and knows what is best for it.

    Man’s biggest goal (at this point) is learning how to live with nature without unintentionally altering it. If nuclear winters, aerosols, methane or CO2 could give us the temperature we wanted, the more important concern would be ‘what do we screw up this time?’

    If you consider man to be nothing but an animal, then the Earth deals with us as so. The Law of Conservation of Mass basically states: In a closed systerm, matter cannot be created or destroyed, only changed (except in a nuclear reaction). The minute we became capable of altering the ‘whole’, we endangered ourselves. The earth is an extremely complex system (surprising, I know). Every change we make, be it fertilizer in the soil, a 70 story building in Manhattan, or tearing down a tree, there are repercussions.

    While science has helped man gauge the effect of our ripples on the pond, we’re still working on how to keep the pond’s surface still.

  50. 350
    Joe Rosenfels says:

    If you accept that adding Green house gases to the athmosphere will have a temperature increase (forget the specifics about c02 and ice cores, time delay, glaciers growing, antartic getting thicker etc) see this article.