McKitrick: What the Hockey Stick Debate is About?

Ross McKitrick has an engaging presentation of the Hockey Stick Debate presented on April 4, 2005. Here is the abstract:

The hockey stick debate is about two things. At a technical level it concerns a well-known study that characterized the state of the Earth’s climate over the past thousand years and seemed to prove a recent and unprecedented global warming. I will explain how the study got the results it did, examine some key flaws in the methodology and explain why the conclusions are unsupported by the data. At the political level the emerging debate is about whether the enormous international trust that has been placed in the IPCC was betrayed. The hockey stick story reveals that the IPCC allowed a deeply flawed study to dominate the Third Assessment Report, which suggests the possibility of bias in the Report-writing process. In view of the massive global influence of IPCC Reports, there is an urgent need to bias-proof future assessments in order to put climate policy onto a new foundation that will better serve the public interest.

The full text is here.

UPDATE: Also see my Ohio State presentation for a more recent review.


  1. Louis
    Posted Apr 8, 2005 at 6:46 AM | Permalink

    This paper remarkably easy to read and understand. Thanks for publishing this.

  2. John A
    Posted Apr 8, 2005 at 7:07 AM | Permalink

    Ross’ critique is hard-hitting, honest and clear. There must be more papers like this.

  3. Dr Roger Bell
    Posted Apr 8, 2005 at 8:58 AM | Permalink

    The dates given on each page of the talk are 2003 – shouldn’t they be 2005? It is an excellent paper.

  4. Dave Dardinger
    Posted Apr 8, 2005 at 11:18 AM | Permalink

    I agree that the paper is easy to read and helps to make clear some of the points which are difficult to understand. My only complaint is a trace of triumphalism, especially at the end which will be off-putting to those who want to read it to make up their minds. Of course skeptics who need bucking-up will probably take heart for the same reason.

  5. Ross McKitrick
    Posted Apr 8, 2005 at 11:28 AM | Permalink

    Yes, the 2003 is a typo (one of several, alas). Should be 2005.

  6. Jaime Arbona
    Posted Apr 8, 2005 at 8:57 PM | Permalink

    This has cleared up a lot of questions I had due to my lack of expertise in this field. Thanks a lot. And if there is a hint of triumphalism I believe it is well-deserved and does not detract at all from the excellence of the paper.

  7. Michael Mayson
    Posted Apr 9, 2005 at 1:03 AM | Permalink

    Thanks for an excellent summary of your work. There is one thing I have been meaning to ask for some time. You have demonstrated that Mann’s PC analysis has no statistical significance – i.e. the input may as well have been random noise. Have you found that this is also likely to be true of any attempt at extracting temperature signals from tree ring proxies?

  8. John A.
    Posted Apr 10, 2005 at 10:26 AM | Permalink

    I have added this article to the “Favorite Links” link.

  9. Paul Linsay
    Posted Apr 10, 2005 at 3:02 PM | Permalink

    To follow up on #7, it seems like there are a lot of different causes that could confound an attempt to extract temperature from tree rings. For example: how do you distinguish hot dry weather from cold dry weather, the tree isn’t going to grow in either case? Suppose the weather is cool but wet, is that really different enough from warm and wet? Trees only grow in the daytime and during the spring and early summer. How do you get any kind of signal from the night and the other 9 months of the year? What if a tree has been shaded by others and they die off, it will look like a warming. Conversely if a trees neighbors slowly overshadow it, it will look like cooling. I’m sure that there a many more problems with extracting a temperature signal from trees before noise is a problem.

  10. brent
    Posted Apr 10, 2005 at 6:08 PM | Permalink

    A cold, hard look at a hot topic
    Although heavily outnumbered, global-warming sceptics believe the stakes are so high they must step up their fight, as Michael Duffy reports.
    Members of a species widely believed extinct – scientists sceptical of human-produced global warming – met at a conference in Canberra on Monday.

    Kyoto Sceptics Try to Debunk Global Warming Facts

    A bit of press. The first makes at least a semblance of addressing issues
    The second levels the predictable charges of heresy,the usual AGW religionists line

    Thanks Ross for an excellent paper


  11. Ross McKitrick
    Posted Apr 11, 2005 at 1:59 PM | Permalink

    Regarding Michael’s point (#7), the red noise simulations don’t provide a general result about the temperature information in tree ring data. They only apply to MBH98 data and the MBH98 treatment thereof. Other attempts to extract temperature info from a matrix of tree ring chronologies using a statistical fitting procedure have to pass statistical tests benchmarked with reference to the characteristics of the specific data set being studied.

  12. Robert Nisson
    Posted Jun 3, 2005 at 2:33 PM | Permalink


  13. Ken St.Andre
    Posted Jun 8, 2005 at 8:09 AM | Permalink

    Thank you for a very informative article! The piece I still don’t understand is why would so many highly educated people, obviously well placed in society support this lie to the public? I assume there is money somewhere. Is it because the lie changes the flow of research funds or does it create a new fake industry of “pollution control”? What then is Kyoto really about?


  14. Peter Wimsett
    Posted Jun 11, 2005 at 11:52 PM | Permalink

    Thank you for your hard work. From my accountant’s point of view, an audit of IPCC reports should identify material variances through substantive testing and review of IPCC processes – and add credibility to the IPCC conclusions. Usually such audits are completed before reports are made public, with errors already corrected and are published with an independent audit opinion/statement. I note that there may be a lot at stake for some at each end of the continuum of the debate/science. I agree that the proponents of the existence of cimate change should be excluded from any audit team. It is also necessary for the proponents of no climate change to be excluded from such an audit team. The role of an auditor is to have an open mind to all options when conducting an audit. This neutral starting point when reviewing material must be both actual and in appearance – for example, without financial interest or influence (past, and future if possible!). They also need to have the technical expertise to conduct the audit.

  15. Ted Hamilton
    Posted Jun 12, 2005 at 2:23 PM | Permalink

    I was left asking myself the same questions as Ken St Andre above, and plan to dig a little deeper into that subject. What on earth is going on here?

  16. Henry Adams
    Posted Jul 20, 2005 at 9:42 AM | Permalink


    You idiots have demonstrated an aptitude for data manipulation

  17. John-Paul Frazer
    Posted Jul 24, 2005 at 7:14 AM | Permalink

    Whatever the ‘facts’ on either side of the debate, what do the readers/ editors of this post think about risk assessment?
    The likleyhood of climate change causing impact is debated and unknown; the potential impacts from climate change are also debated and unknown but potentially severe or catastrophic.
    The possible risks and implications of being wrong about climate change are, at worst, mild embarassment.
    So why not take a precautionary approach?
    Admittedly there have been some predictions about the environment, population, culture etc that have not come to pass (also some that have…) – but isnt it a bit stupid to lump all these failed predictons together as ‘greenies crying wolf’ then forevermore ignore warnings…?

  18. Greg F
    Posted Jul 24, 2005 at 7:50 AM | Permalink

    RE: #17

    The likleyhood of climate change causing impact is debated and unknown; the potential impacts from climate change are also debated and unknown but potentially severe or catastrophic.

    The same could be said about getting in your car and driving to the store. The other possibility you fail to consider is the impact may be beneficial.

    The possible risks and implications of being wrong about climate change are, at worst, mild embarassment.

    So why not take a precautionary approach?

    The “precautionary approach” is not without risks and tradeoffs, which I would argue, is the fallacious assumption in your argument. Your assuming that the “precautionary approach” has no cost (other then mild embarrassment). This is clearly not true, as limited resources devoted to the “precautionary approach” would not be available for other uses. And were not talking chump change here.

  19. John-Paul Frazer
    Posted Jul 24, 2005 at 4:11 PM | Permalink

    The same could be said about getting in your car and driving to the store.

    Not quite the same! – I take precautions when I drive my car, like looking ahead, assessing risks and taking necessary precautions. Its also my choice to drive – I take the risk for my own life.

    The other possibility you fail to consider is the impact may be beneficial.

    There may be some benefits of a small increase in temperature – I dont know. My question was: What about the worst case case scenario? This is not just better suntans and pineapples in the UK – the worst case is a runaway greenhouse effect – runaway…

    The “precautionary approach” is not without risks and tradeoffs, which I would argue, is the fallacious assumption in your argument.

    What are the risks and tradeoffs of reducing CO2 output? We are running out of cheap fossil fuels anayway so we have to make a transition sometime or other. Well designed precautionary measures could be taken in ways that would save money and resources, whilst creating jobs and boosting technology innovation.

  20. Greg F
    Posted Jul 24, 2005 at 5:17 PM | Permalink

    Not quite the same! – I take precautions when I drive my car…

    You should take the same precaution when you read what somebody wrote. In the case of the car the risks are real no matter how safe a driver you are (there are other people on the road). In the case of GW the risks are the output of a video game.

    There may be some benefits of a small increase in temperature – I dont know. … the worst case is a runaway greenhouse effect – runaway…

    That’s correct, you don’t know and therefore do not know what the worse case could be. Just for the sake of argument lets assume the CO2 is having a significant effect. Lets also assume that the earth is on the verge of plunging into a ice age. If we keep adding CO2 we delay or cancel the ice age, if not we plunge into a ice age. Now what is the worse case? This just gave me an idea. I am going to start a church and all members will pay me a tithe. If you don’t join my church you will go to a very hot place when you die. The worse case is, you don’t join and pay me, and therefore go to that very hot place. Of course you don’t know if this is true but according to your “precautionary principal” I should expect a check from you.

    What are the risks and tradeoffs of reducing CO2 output?

    The tradeoffs is those limited resources spent on reducing CO2 cannot be spent on things like 3rd world hunger, medical research, technological innovation ect ect. The risk is you will spend billions on a hypothetical problem at the expense of real problems and have nothing to show for it.

    We are running out of cheap fossil fuels anayway so we have to make a transition sometime or other.

    The stone age did not end because we ran out of stones.

    Well designed precautionary measures could …

    And who is going to do this design?

  21. John-Paul Frazer
    Posted Jul 25, 2005 at 3:52 AM | Permalink

    You enjoy metaphors! Problem is there’s a metaphor to boost any weak argument.

    The car thing is ridiculous… I could just as well say ‘What if you are driving along, fast, and crowds of people along the roadside start waving at you and shouting ‘cliff ahead!’ a few people are saying ‘Well actually it may be cliff, it may be hill, it may be a small bump!’ what would you do? Slow down and take a look for yourself presumably. Two points here – ‘take a look for yourself’ which is what I admire the skeptics for doing, the other is ‘slow down’ which is just a sensible precaution – and I don’t see a conflict.

    “The worst case of GW the risks are the outputs of a video game” I imagine that you are saying that computer modelling is more of an art than a science? Well that can be true – although modellers know this and are always striving to improve their models so that they converge on reality. I work with modelling software for building design – and it is pretty rough stuff, but as a designer it gives me a good feel for things, and they are always in the right ball park. Perhaps thats somehow different for climate change and planetary geobiophysics as it is a complex area! I recently spoke with James Lovelock who explained that the model he is looking at shows a runaway greenhouse effect kicking in at 400 – 600ppm – so thats pretty rough as models go! However I also saw the fear in his eyes… Worst case is a runaway greenhouse effect. I can say that’s a worst case because the Earth has previously oscillated between ‘ice ages’ and ‘fevers’, this could be terminal – look at Venus – this is an example of a planet with a runaway greenhouse atmosphere.

    THe hell threat didnt work with me because I’m a skeptic. We are suckered into all kinds of belief systems – consumerism is a good example (Buy this latest fashion accessory and be a sexy starlet, if you dont… you will be ridiculed and ostracised!) I am not entirely suckered by these various ‘threats’ which also include those implied by some of the skeptics “Keep on driving your SUV, dont worry about climate change its too expensive to mitigate and besides we should be spending our precious resources on developing Africa so they can buy SUVs too.” Crazy logic.

    The tradeoffs is those limited resources spent on reducing CO2 cannot be spent on things like 3rd world hunger, medical research, technological innovation ect ect. The risk is you will spend billions on a hypothetical problem at the expense of real problems and have nothing to show for it.

    Do you really want a discussion on win-win-win alternatives? Take it from me – as a design consultant working in this ara for over 20 years – that there are.

    Are you SURE, absolutely SURE thats there’s no problem? Because if you do end up selling your belief system are you are wrong you will have a lot of questions to answer your children.

    RE Peak Oil article – I read it sometime ago – its a very simplistic, with lots of ignorant assumptions… but I liked some of the points – especially the title! However, I really cant be bothered demolishing it for you. Just to say that technology is not a panacea (and I’m a technophile btw). You cant leave everything up to market forces – first we would need a perfect market (which we dont have) and then there’s morality – which is why we have laws and regulations. Innovation can be done quickly (e.g. in war time) – but there are some potential hurdles with GW and PO – energy prices will increase as resources diminish, energy returned on energy invested also diminishes – if we leave it too late there wont be enough readily available oil to build the new infrastructure required (whatever the technological innovation (unless its cold-fusion)).

    So who is going to do the designing?
    Everyone is a designer: Its about looking ahead – deciding where you want to be (where to you want to be?) – then planning a course. There are plenty of (win-win-win, factor 10, whatever) solutions around which I could begin to signpost for you. Does your stance depend on this issue?

    All in all I think the risks are acceptable “spend billions on a hypothetical problem at the expense of real problems and have nothing to show for it.” vs “do nothing and risk, worse case, a Venutian climate.” though I would rather say “redirect billions on a problem with mounting evidence for concern (Co2 is ONE problem closely related to other types of negative impact), and simultaneously solve many of the real problems of the world.” vs “…Venutian Climate.”

  22. Pat Boyle
    Posted Aug 26, 2005 at 1:11 PM | Permalink

    What if the hockeystick were true? That would lead to runaway greenhouse heating like we see on Venus. Right? Consider that if we double the CO2 concentration in out atmosphere it would still be less than one tenth of one percent. On Venus CO2 is almost 97% of the atmosphere. Also consider that the atmosphere on Venus is nearly 100 times as dense as ours. On the face of it runaway greenhouse on Earth based on the Venus experience is a very improbable worry.

    The true situation is probably just what most informed people thought before the IPCC and Mann invented the hockeystick. To whit. The Earth has been typically warm (and pleasant) for more than a half billion years. There have been four relatively short ice ages for reasons not perfectly understood. We have been in an ice age for about two million years. For at least the last million years there has been a cycle of about ninety thousand years of cold (very cold indeed) alternating with about ten thousand warm years. Within our present interglacial there seem to be smaller cycles of warmth and cold of about five hundred years. There was the Roman Warm Period follwed by the cold Dark Ages, followed by the Mideval Warm Period, followed by the Little Ice Age. We seem to be about a century into the Modern Warm Period which should last for a couple more centuries if the pattern holds. This is very good news.

    There are only three possibilities for climate: it gets warmer, it gets cooler, or it stays the same. Staying the same would cause us the people of Earth the least disruption but alas stability doesn’t seem to be the long term rule for our planet. Getting warmer might cause some disruptions but this is contoversial. After all the long term demographic trend in America has been towards the “Sun Belt”. However it is very clear that an end to our interglacial period and a return to ninty millenia of continental ice sheets across America is a very, very nasty prospect.

    Luckily we don’t seem to have to worry about that. We probably have about three of four hundred years of good (warm) weather ahead of us.

    I suspect that the whole global warming issue is about to disappear along with environmentalism in general. I give it maybe twenty more years as a political factor with the general electorate. Even now educated people have grown sceptical of environmental scares. Worrying about the environment is so seventies. Its like platform shoes and disco music. The record is clear. Every time there is an environmental crisis there is prompt and effective public and private action such that the problem is solved.

    • Gogo
      Posted Nov 23, 2010 at 4:15 PM | Permalink

      Agree with a lot except with the first and last paragraphs.
      Percentages for a greenhouse gas means little without taking into account the properties of that gas (how much a given amount absorbs heat and what frequencies it absorbs at). I have read up on the physics and calculations involved. There is a lot wrong, or incomplete with climate science but at the very least the properties of CO2 are as certain as environmentalists like to claim all climate science is. Problem is that there are so many feed backs and other phenomenon to consider that the amount of warmth to expect from a quantity of Carbon can be within a broad range. The most prominent Clim skeptics say a low number, while numbers much higher than the “consensus” are around. All of this involves physics that you don’t learn till you take advanced physics classes at an engineering college.

  23. TCO
    Posted Aug 26, 2005 at 8:26 PM | Permalink

    1. Is the term “hockey stick” with its mild negative connotation from business, resented at all by the Mann supporters?

    2. IMHO, MBH likely conducted tendentious rather than truth-seeking research. However, MM should refrain from stating so, instead just continuing to engage on the specific points of error and letting others jump to the next conclusion.

  24. John-Paul Frazer
    Posted Aug 29, 2005 at 8:28 AM | Permalink

    RE 22
    I agree that a runaway effect seems unlikely – but I presented it as ‘worst case’ (worse than an Ice Age!). The only reason we have such a low proportion of atmospheric CO2 is billions of years of photosynthesis. If, as part of a general degradation of the biosphere, there were massive ecosystem collapse then the CO2 sink would be compromised. It has been said that increased CO2 would result in increased photosythesis. This is true up to a point – but from the FACE studies of grond level CO2 there is evidence that this increased growth is more susceptible to pest and fungus attack…

    Regarding your comments about environmentalism dissapearing. Not likely – as long as there are people more concerned with profit than the health of the environment and humans there will always be environmentalists blowing the whistle. You mention that “Every time there is an environmental crisis there is prompt and effective public and private action such that the problem is solved.” Who do you think brings these crises to our attention (it certainly isnt the perpetrators!)

    There are dozens of environmental challenges that are not addressed ‘promptly and effectively’ as you say from dog poop on the pavements to pollutants of greater concern like arsenic and pesticides in aquifers, cocktails of air pollutants off-gassed from modern building materials and household goods, dioxins, chlorinated hydrocarbons, particulates, or of course species loss and destruction of ecosystems etc etc etc… So to me CO2 is a bit of a red-herring – we are running out of cheap oil anyway so hopefully we will make the transition to a more sensible energy source well before the debated tipping points are reached. Basically, much of our ‘civilisation’ is badly designed – inefficient infrastructure and buildings, toxic materials, profligate consumption/ waste etc. These are what will disappear.

  25. Steve McIntyre
    Posted Aug 29, 2005 at 9:29 AM | Permalink

    RE 23: TCO, I don’t think that Mannians (Mannies ?) are even aware of the negative connotation of “hockey stick” from business. There is a remarkable disconnect between academics and civilians. Obviously, business people and investors snicker when they even hear the term hockey stick graph, having seen too many in promotions. But most academics are unaware of the use of “hockey stick” in business graphs and the term as applying to MBH seems to have developed independently.

  26. Dave Dardinger
    Posted Aug 29, 2005 at 10:25 AM | Permalink

    re #24

    “The only reason we have such a low proportion of atmospheric CO2 is billions of years of photosynthesis.”

    Only in a evolutionary sense. The actual turnover of CO2 into biomass is quite fast. My rather old (1994) carbon cycle chart shows 111 GtC turned into biomass each year (61 land 50 ocean) compared to 750 in the atmosphere and 5.5 added to the atmosphere by human activity. Of course this is offset by respiration and decay. But this still means only about 5% of the total flux into the atmosphere is what’s added by humans.

    The question I’d like answered seriously is why anyone who seriously considered the question would think a small sustained additional influx of CO2 would upset the equilibrium? Of course the serious thinkers on either the warmer or skeptic side don’t think so. Instead it’s generally agreed that a lot of the answer is simply that it takes a few decades to reach a new equilibrium. Relatively recently, (compared to the glacially slow increase in solar constant that is), the CO2 level has been much higher and the earth got along fine. But this brings up the actual answer to your assertion quoted above.

    — The low level of CO2 in the earth’s atmosphere is at that level because it’s the lowest which can be sustained given the biochemistry of existing plants and animals. If we had rather more efficient organisms which could compete with existing ones otherwise, the level of CO2 would be driven even lower. But since we don’t, a couple hundred ppm is as low as can be managed on average. But if it gets pushed up temporarily via a comet crash, or rapid volcanism or a rogue species like humans, then that can be handled quite nicely and geologically we just see a temporary blip as plants feast on additional free food for a while. The temperature rises somewhat, but on balance changes in the water cycle compensates for more greenhouse effect by CO2.

    Now there’s an alternative viewpoint as to temperature and CO2 levels which I don’t think’s been adequately addressed. That is that our increasing CO2 levels are primarily being pushed by increasing temperatures instead of the other way around. With the feedbacks available and being argued in discussions of the CO2+ => t+ scenario and the time delays from things like melting glaciers and warming ocean reservoirs it’s not as much a slam dunk to dismiss this alternative as you might be thinking.

  27. John-Paul Frazer
    Posted Aug 29, 2005 at 12:56 PM | Permalink

    Thanks – I didn’t realise the flux was so great. Do you know then why CO2 is still rising when in theory only 5% extra new growth should sink all the man made CO2 in one go? Plants should be able to do this – if you double CO2 levels in a greenhouse 30% extra growth is possible.

  28. Dave Dardinger
    Posted Aug 29, 2005 at 1:53 PM | Permalink

    re:#27 Well, the need for respiration, replacement of leaves, etc means the net increase doesn’t increase that much, but you’re right additional CO2 should increase biomass and that’s been seen to some extent, but that’s also why I brought up the question of increased temperatures also causing CO2 increase.

    To some extent, I think, both sides tend to just point to the things which improve their position. Thus you’ll find warmers pointing out that warming temperatures warm and melt permafrost which in turn releases CO2, etc. But they tend to ignore that the same melting will give longer growing seasons and more peat formation, etc. So it’s hard to say exactly how things will work out in the short run.

  29. McCall
    Posted Jan 1, 2006 at 11:52 PM | Permalink

    It’s the holiday, so I’m catching up on reading …

    Figure 4 (data from Huang et al) is also in Taken By Storm, Figure 5.6 (which I just finished and enjoyed reading) — is there data from 1900-present to update/extend the graph?

  30. McCall
    Posted Jan 2, 2006 at 8:06 AM | Permalink

    Presumably S. Huang had forwarded data from Huang et al. ’97, updated from Huang et al. ’00 (after MBH’98 and MBH’99), then most recently Huang’04 which covers 1500-1980 (after Taken by Storm was published)? Huang’04 is found in the Wikipedia spaghetti graph — with color choices and one’s monitor (especially if flat panel LCD), can be tough to discern.

    BTW, is/does an update or an errata planned/exist for Taken By Storm?

  31. Steve Sadlov
    Posted Feb 7, 2006 at 8:11 PM | Permalink

    I am fairly well familiar with the area where those Bristlecones were assessed. It is in a microclimate within the already quite unusual general climate at the western edge of the Great Basin. It is located on an overall range of mountains, second only to the Sierra Nevada, in which rainshadow they lie. Many of the typical rules applicable to “Mid latitude” climate do not apply there. For example, the Sierra Nevada interdict vast percentages of “straight on” moisture – e.g. that riding on cyclonic disturbances coming in on a standard Westerly. And that Westerly is often blocked by the Pacific High, during short periods during our Rainy Season and almost 100% of the time during our (late Spring – Mid to Late Fall) dry season. The seriously heavy dumps of snow come in the winter when a “Siberian Express” gets set up and the far more rare summer dumps of rain are almost entirely the result of the typical Monsoon (e.g. moisture coming up from the Gulf Of California and more rarely the Gulf of Mexico when the Pacific High retrogrades further off shore). I reckon the trees grown more when the snowpack has been more massive, again during years when the Siberian Express has been dominant.

    So, bottom line is, they used as a proxy trees which are an unusual species living in a highly unusual climate, where growth would not tend to follow the pattern seen in forests located in truly Continental or Maritime climates such as is the case of Gaspe and Arkansas. Let me say that using Bristlecone proxies is utterly ill advised under any normal rules of selection of proxies broadly representative of conditions affecting a broad areal distribution of flora.

  32. Steve Sadlov
    Posted Feb 13, 2006 at 10:15 AM | Permalink

    As yet another “proxy” of just how pervasive the Hockey Team’s efforts have proven to be, I present this forum with the following missive at, of all places, the USNOAA site:

    Key excerpt:

    = The idea of a global or hemispheric “Medieval Warm Period” that was warmer than today however, has turned out to be incorrect.


    (Fruadulent hockey stick graph which we all know and love follows immediately below that particular text ….)

    • Gogo
      Posted Nov 23, 2010 at 4:27 PM | Permalink

      confusion detected. About that last point.
      the ‘hokey stick’ graph in the image below that text is not the one famous for being erroneous. It is similar, same concept, but known to be a version in which the errors that MacIntyre pointed out have been corrected (I have seen this one before).

      Also, could not find the excerpt you pointed out.

      nothing known to be wrong with NOAA.

  33. Steve Sadlov
    Posted Feb 22, 2006 at 3:12 PM | Permalink

    A brief anecdote showing how Gaia worship and Ecotopian idealism may have a role in the “consensus” about AGW held by the orthodxy of “climate science” community.

    Back when I was an undergraduate, as I have alluded to on other threads, I was also a Gaia worshipper and Ecotopian idealist. I distinctly recall the following incident in that regard. We were returning from some field work, about half a dozen of us in a Carry All. Somehow the conversation turned to some or some other environmental policy matter and I spewed the standard “Green” point of view. Mind you, this was back in the early 1980s, when, in the midst of hard rock geology and geophysics candidates, I would have been, shall we say, at my peril making such a statement. Of course, as one might expect, after I blurted out my youthfully romantic nonsense, I was told by a country boy riding next to me that I must be a “quaternary urbanite.” At the time I seethed with anger (but did not let it show) and thought that most of my fellow candidates were “rapers of the earth” and “future tools of the capitalist mennace” etc.

    Thankfully, I grew out of such temporary youthful insanity. But I reckon that Mann, and others, who came through the system only a few years after me, must have also had similar experiences as I did. But instead, I reckon they decided then and there to figure out how to work within the system to carve out their niches within which there Gaia notions might overturn the classical norms regarding Earth Sciences. These Quaternary Urbanites, instead of eventually seeing the light and realizing the wisdom of country boys swinging mason’s hammers, clung to their politically oriented utopianism and by the by, became enlisted into an army of modern day Malthusians and Doomsayers who live for the day that Man may be whacked down a notch.

  34. Peter D. Tillman
    Posted Jun 28, 2006 at 10:57 PM | Permalink

    Back when I was an undergraduate, as I have alluded to on other threads, I was also a Gaia worshipper and Ecotopian idealist.

    James Lovelock, author of the Gaia hypothesis, is currently campaigning for nuclear power, as a way out of global-warming. And, in his interesting memoir, Homage to Gaia, he has kind words for the industries he’s worked in, especially Shell Oil.

    He’s a very interesting independent scientist, a fiercely-independent iconoclast, and an old-fashioned, very British eccentric scholar. You might enjoy the book:
    (scroll down for my review)

    Happy reading–
    Pete Tillman

  35. Posted Nov 15, 2006 at 2:46 PM | Permalink

    Thanks for a superb article on a pivotal area of the climate change debate.
    What is the current status of this argument? Has the result of MBH98 been independently replicated or verified yet? I have just finished ‘The Rough Guide to Climate Change’ published
    only in Sep 06 by Robert Henson. He presents the MBH99 graph on p.216 and says that while sceptics still challenge it,
    -‘A 2006 report by the US National Research Council supported most of Mann’s conclusions while noting that the sketchiness of proxies prior to 1600 adds some uncertainties.’
    My guess is that MBH98 remains a desperate secret yet it is significant how Henson chose not to disclose this ‘uncertainty’ associated with it. The Rough Guide is an important book because just as the politicians read the ‘Summary for Policymakers’, the general public will read the Rough Guide and vote accordingly.
    Keep up the good work.

  36. Ross McKitrick
    Posted Nov 15, 2006 at 3:06 PM | Permalink

    Supported most of Mann’s conclusions? Hardly. They accepted all our criticisms: the PCA method is biased, the results all depend on bristlecones, the bristlecones should not have been used, the reconstruction lacks statistical significance, the error bars were understated. At the press conference, one of the panellists (Wallace) made an offhand comment that in his view the hockey stick was probably right: this became the headline in media coverage, but was his own opinion and is at odds with the text of the report. The report itself says that little confidence can be placed in Mann’s conclusions about the 1990s being the warmest decade, or 1998 being the warmest year, in a millennium.
    A month after the NAS report came out, the Wegman panel released its report, which is discussed elsewhere on this site. It was even more scathing in its criticism of Mann’s work. At the hearings before the House Energy and Commerce Committee in July, the Chair of the NAS panel (Gerry North) indicated his panel was in basic agreement with Wegman’s concerning the hockey stick graph.
    Talk about denialists.

    • lingo
      Posted Nov 23, 2010 at 4:37 PM | Permalink

      there are varying degrees of denial.
      By support, the only thing they can say comes close to “support” is that in spite of all the errors in that graph, those investigations agreed that the world was indeed getting warmer.
      It is easy to see that a poorly informed person hearing that would exaggerate or confuse what the panel results were.

      Denial would be denying the temperature measured outside.

  37. Steven Douglas
    Posted Mar 19, 2007 at 8:05 PM | Permalink

    As yet another “proxy” of just how pervasive the Hockey Team’s efforts have proven to be, I present this forum with the following missive at, of all places, the USNOAA site:

    Key excerpt:

    = The idea of a global or hemispheric “Medieval Warm Period” that was warmer than today however, has turned out to be incorrect.

    I just came across this myself, and am beyond amazed. Why is that page unchanged after all this time? Are they still maintaining or defending the validity of the hockey stick?

    • lingo
      Posted Nov 23, 2010 at 4:39 PM | Permalink

      Someone else already commented. Not the same chart, not the same flaws. NOAA does not deserve your insults.

  38. TAC
    Posted Mar 19, 2007 at 8:54 PM | Permalink

    Steven (#37) The page says it was

    Last Updated Friday, 10-Nov-2006 16:03:24 EST

    This is four months after the NAS Report and the Wegman Report. Bizarre!

  39. MarkW
    Posted Mar 20, 2007 at 5:36 AM | Permalink

    I’ve had debates with people who claim to be scientists, and they tell me with a straight face that NAS confirmed that Mann was
    accurate. They will then tell me how NAS showed, conclusively, that today’s climate is warmer than the MWP.

    Never discount the ability of humans to see what they want to see.

  40. Philip B
    Posted May 23, 2007 at 5:44 PM | Permalink

    The significance of the HS and whether the MWP was warmer than recent times is that the prediction we will see catastrophic runaway warming depends on CO2 levels driving temperatures to levels not previously reached and triggering feedbacks not previously triggered.

    The physics of the CO2 greenhouse effect means that as CO2 levels rise the additional warming caused progressively decreases. I’ll go with Steve Milloy’s number of 0.7C as the maximum temperature rise increases in CO2 will cause through the greenhouse effect. Clearly not enough to worry about.

    In order to get more warming than this, positive feedbacks are needed. The IPCC claimed that because observed warming was more than twice the amount the increased CO2 should cause, this was clear evidence that positive feedbacks do exist.

    I assume these feedbacks result from temperature alone and not directly from CO2 levels or some combination of CO2 and temperature.

    If the MWP (or the RWP) was warmer than modern times then these feedbacks should have been triggered and the world already warmer by 5C (or whatever number is used for catastrophic warming). The fact that it isn’t means either the feedbacks don’t exist, or modern times is warmer (or at least equally as warm) as the MWP. A third possibility that a new feedback has been introduced since the MWP begs the question what is it and why aren’t we doing something about it, since presumably it results from human activity and is a bigger problem than CO2.

    This is the reason they have to get rid of the MWP. If the MWP was warmer than current times, one would have to conclude catastrophic warming from rising CO2 levels is not possible or that CO2 isn’t the real problem.

  41. MarkW
    Posted May 23, 2007 at 6:26 PM | Permalink


    I could of sworn that I’ve read that absent any feedbacks, the rise in CO2 that we’ve seen over the last 100 years would have resulted in a bit less than a 1 degree warming. We’ve seen about a 0.6 degree increase.

    Of that 0.6, some portion is caused by GHG’s, some portion is caused by sun/cosmic rays, some portion is caused by UHI contamination.

    Even if we were to assume that GHG’s were the cause of 100% of the increase, that would still mean we were seeing a bit over half the potential rise. That to me spells negative feedback, not positive.
    The more of the warming that is actually due to he sun and UHI, the stronger this negative feedback becomes.

  42. MarkW
    Posted May 24, 2007 at 5:24 AM | Permalink

    #40, and 41,

    My bad, 1C is that amount of warming that we would expect from a doubling of CO2 from the pre-industrial level.
    The increase in CO2 that we have had so far, is enough to produce about 3/4ths the value expected from doubling.
    Since the numbers bandied about for warming so far are 0.6 to 0.7, this is in the ball park for the expected amount of heating for the increase in CO2 that we have seen so far.

    That is of course, assuming that 100% of the heating we have seen so far, is due to CO2.

  43. Steve Milesworthy
    Posted May 24, 2007 at 5:54 AM | Permalink


    Yes the real argument is about feedbacks.

    Basic thermodynamics, and the reasonably widely accepted greenhouse effect of CO2, says that if all else remains constant, a doubling of CO2 from 290-580 ppm raises temperatures about 1C.

    The current level of CO2 (380ppm) would by itself raise temperatures about 0.4C (though given the ocean takes time to warm up – it is not at equilibrium temperature yet).

    So something else caused the other 0.4C+ warming (the 0.6C figure is 20th century warming). IPCC says it is partly the sun but the sun did not cause the most recent spell (there is no good evidence for cosmic ray effects).

    However, the above shows we are likely looking at positive feedbacks not negative ones. Also, if, for example, cloud feedbacks are negative, how come we got changes of 5-10C over the ice age cycles?


    There is no reasonable “maximum temperature” for the likely amounts of CO2 we will get in our atmosphere – more CO2 always equals more effect.

    I don’t think anyone is saying that the MWP was warmer than the LIA due to CO2, but you are correct in saying that many feedbacks are temperature-related, not CO2 related. Eg the cooling following Pinatubo would not have been so significant without the expected water vapour feedbacks.

  44. Hans Erren
    Posted May 24, 2007 at 6:24 AM | Permalink

    re 43:
    I was under the impression that Pinatubo prooved that watervapour feedback is not as strong as expecyed.

    Climate forcing by the volcanic eruption of Mount Pinatubo
    Douglass D. H., R. S. Knox


    We determine the volcano climate sensitivity λ and response time Ï„ for the Mount Pinatubo eruption, using observational measurements of the temperature anomalies of the lower troposphere, measurements of the long wave outgoing radiation, and the aerosol optical density. Using standard linear response theory we find λ = 0.15 ⯠0.06 K/(W/m2), which implies a negative feedback of ‘ˆ’1.4 (+0.7, ‘ˆ’1.6). The intrinsic response time is Ï„ = 6.8 ⯠1.5 months. Both results are contrary to a paradigm that involves long response times and positive feedback.

  45. Philip B
    Posted May 24, 2007 at 6:31 AM | Permalink

    There is no reasonable “maximum temperature” for the likely amounts of CO2 we will get in our atmosphere – more CO2 always equals more effect.

    Yes, but will it result in progressively more, less, or the same effect. And more importantly will the effect tend to zero as I understand the physics. And if the tendency is to zero what is the net warming from a particular increase – let’s say 200 ppm from here.

    Actually , I parsed your statement and took out the fudge and got,

    There is no “maximum temperature” for the amounts of CO2 we will get in our atmosphere – more CO2 always equals more effect.

    I’d say the first statement is false because at some point CO2 concentrations are high enough to block effectively all radiation at the frequencies CO2 blocks radiation and equilibrium is reached with no additional warming, and while the second is true in a narrow sense, it in no way supports the first statement and looks like a spurious justification to me. More harshly, I say it’s an attempt to avoid the issue.

    • lity
      Posted Nov 23, 2010 at 4:45 PM | Permalink

      Do not know where the source for those quotes is. Normally books have a version of that comment in which they explain that there is always an effect within a certain range of concentrations. They also specify that the plateau is at much higher concentrations than we are likely to ever see on earth.

      I do not know who wrote the comment that you are quoting from but I think the person just misunderstood what he read somewhere.

  46. MarkW
    Posted May 24, 2007 at 6:49 AM | Permalink

    The sun is more active today than it has been in the last 8 to 9 thousand years. There is no good evidence for cosmic rays, only if you ignore all of the good evidence.

    As to the role of CO2, some 20 or 30 million years ago, the level of CO2 in the atmosphere was about 17 times greater than what we are seeing today. And by the way, the earth was also in the middle a glaciation cycle.

    There is no evidence, good or otherwise, that CO2 is a major mover of climates.

    • long
      Posted Nov 23, 2010 at 4:55 PM | Permalink

      30 millions years ago was not in the middle a glaciation cycle. It was around the time the first permanent ice at the south pole was forming but a lot warmer than today. Definely not an ice age.

      You may have read the same paper about the suns activity as I read. That one has been challenged by later papers working on the same data. The corrections used for the 8Ky paper introduced a bias (reminds me of the hokey graph).

      You do not explain what your standards for “good” or not “good” evidence are (or even what your point is about cosmic rays). I hope you did more of your homework on cosmic rays than you did for your other topics.

      “no evidence for Co2” comment. I have heard this one before a million times. Try refuting evidence rather than denying its existence. Everyone I have ever heard make this argument uses arbitrary and counter intuitive standards for what is and isn’t evidence. Either that or they are just ignorant.

  47. Steve Milesworthy
    Posted May 24, 2007 at 7:14 AM | Permalink


    Interesting citation. Will have a look. Though when I looked in Google Scholar it seemed that at least 2 other papers had quite strongly disputed it, for example:

    Comment on “Climate forcing by the volcanic eruption of Mount Pinatubo”by David H. Douglass and Robert S. Knox: A. Robock GRL Vol 32

    The following has a different opinion at least.

    “Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor” Soden et al, Science 26 April 2002


    Sorry about the fudge. The fudge was because at current levels, the response to CO2 increase is essentially logarithmic – double CO2 and forcing goes up 4W per metre squared. But to get another 4 watts you need to double it again. However, for much smaller (eg. where none of the bands are saturated) or much larger amounts of CO2 (about 10% CO2) the response function is different. But we’ll all be dead before we hit 10% CO2!

    It’s actually a bit more complicated than that. It’s not totally about how much infrared from the surface that is blocked (currently about 90% of surface emissions is absorbed by greenhouse gases), its also about the height within the atmosphere from which radiation escapes. More greenhouse gases increase atmosphere opacity. So the characteristic level in the atmosphere which emits to space gets higher (and therefore colder). Hence the earth radiates less heat into space until it warms up a bit and gets back into balance.

  48. Steve Milesworthy
    Posted May 24, 2007 at 7:28 AM | Permalink


    Is this getting too far off-topic? I’m new here.

    If there is so much good evidence, how come we still see the graph from Friis-Christensen 1991 being reproduced even though it is accepted that the last few points (where solar cycle lengths match the recent rapid increase in temperature) were due to incorrect arithmetic?

    I am a slow reader though, and have only got as far as 2004 with this story, so any help appreciated in finding responses to the Damon and Laut criticisms:

  49. jae
    Posted May 24, 2007 at 10:07 AM | Permalink

    46: You should put continue this discussion on Unthreaded.

  50. Posted May 24, 2007 at 12:27 PM | Permalink

    Re #48:

    See the reaction of Friis-Christensen on that article here.

    More discussion on solar-climate relations can be found at ClimateAudit

  51. Steve McIntyre
    Posted May 24, 2007 at 12:29 PM | Permalink

    Laut’s methodology consists of first writing false accusations, then totally neglecting the refutations, and finally referencing his very own claims as corroboration when publishing new accusations

    Sounds like the Team.

  52. Steve Milesworthy
    Posted May 24, 2007 at 1:45 PM | Permalink


    It doesn’t seem to have been formally published. I note in the reaction they say that the 1991 paper noted that the correllation for northern temperature beyond 1985 no longer worked “leaving room for other explanations, including anthropogenic effects”.

    Svensmark theories seem very woolly – there might be a fit between solar cycles and clouds (or low clouds, (during the last solar cycle)) that might be caused by cosmic ray numbers that might influence CCN and the clouds might influence temperature.

    That’s my last word on this here – I’ll try to stick on topic in future.

  53. John Lang
    Posted May 24, 2007 at 3:03 PM | Permalink

    In regard to the Friis-Christensen solar cycle theory and Laut’s incorrect arithmetric assertion …

    I just went back and looked at the length of the last few solar cycles and it seems that Laut is the one who made the arithmetic errors (I’ve seen this paper posted all over the place and I always assumed it was right.)
    Well, it isn’t.

    solar cycle
    18 – 10 years 2 months – ending in April 54;
    19 – 10 years 6 months – ending in Oct 64;
    20 – 11 years 8 months – ending in June 76;
    21 – 10 years 3 months – ending September 86;
    22 – 9 years 7 months – ending May 96;
    23 – 11 years and counting;

    Warming until the mid-40s as the solar cyle shortened – Cooling until the mid-70s as the cycle lengthened – Warming again – Peak temperature 1998 – cooling since. The current cycle is already 11 years long and there should be some cooling according to this theory. I’m sure the data would show that if it wasn’t for the Team and Hansen and the Jones’es.

    • long
      Posted Nov 23, 2010 at 4:59 PM | Permalink

      timing for your warming and cooling is off.

      RomanM: You have now posted under the names:


      This type of trollish behavior is a sign of an extremely childish and immature individual who in my opinion we can all do without.

      I have not deleted the comments (although I am hoping Steve will decide to do so), but the next time you post without properly identifying yourself, all of your comments are unrecorded history.

  54. richard
    Posted May 24, 2007 at 6:45 PM | Permalink

    Re: #48 Does anyone else find it somewhat surreal for the Damon Laut comment to complain about “questionable handling of the underlying physical data” and the partially filtered series ends in the Friis-Chistensen Lassen paper, and then turn around and use a smoothed, truncated Mann et al 1998 series without comment….

  55. PaulM
    Posted May 25, 2007 at 3:44 AM | Permalink

    #48 #52:
    The reason Friis-Christensen’s response is not published is that EOS refused to publish it! This is fairly astonishing given that the Damon and Laut article is just an attack on F-C. EOS is not a proper science journal – more of a newspaper. One does not have to be an expert in the field to see that the Damon & Laut article is nonsense. Just look at D&Ls Fig 1b, where they claim to be finding errors in L&FC, and look back at L&FC – that fig is not there! ‘Strange errors’ indeed. The irony is that D&L and with a section on ‘Public impact of misleading information’.
    (sorry, yes, this really should be in unthreaded).

  56. penny packer
    Posted Jun 5, 2007 at 11:08 PM | Permalink

    Re; what is your source for co2 being 17 times higher during a glaciation

    Thankyou CA great site

  57. DaleC
    Posted Nov 27, 2007 at 5:26 AM | Permalink

    re #37 and 38, Still unchanged:

  58. Mick Taylor
    Posted Dec 7, 2007 at 11:22 AM | Permalink

    The Hockey Stick pdf file partially opens then hangs with errors. Will you check this file?
    Thank you.

  59. Cliff Huston
    Posted Dec 7, 2007 at 11:40 AM | Permalink

    #60 Mick,

    The file opens fine here – Acrobat 6.0.6 on a Mac.


  60. jonjones13
    Posted Dec 12, 2007 at 6:15 AM | Permalink

    I work for a major developed countries’ national Met Service. I went to a seminar yesterday in which our own climate modellers showed evidence of global cooling since 2001. The graph was greeted with sneers and chuckles from the mainly climate modeller audience – why?? For most climate researchers science went out the window a long time ago, it is such a biased one sided aregument these days that people like me are terrified of being branded a heretic for even challenging the accepted so-called evidence. These people aren’t scientists, just sheep. It is the so-caller skeptics who are the actual scientists these days, isn;t science about looking at things with an open mind and trying to find the truth…

    Excellent paper by the way…

    • Skiphil
      Posted Dec 8, 2012 at 3:37 PM | Permalink

      This is a fascinating anecdote. This sort of setting must be even more “interesting” now for such seminars and meetings.

  61. Sam Urbinto
    Posted Dec 12, 2007 at 12:14 PM | Permalink

    17 times higher in a glaciation? I think not. These images at

    CO2 400 thousand years

    CO2 500 million years

    Temp 12 thousand

    Temp 450 thousand

    Temp 65 million

    Temp 542 million

    Recent GHG (not including water vapor or ozone)

    Radiation transfer of light from .2 to 70 micrometers

    Greenhouse effect

    All boinging down to….

    “Recent measurements indicate that the Earth is presently absorbing 0.85 ± 0.15 W/m2 more than it emits into space (Hansen et al. 2005)”

    Otherwise known as
    James Hansen, Larissa Nazarenko, Reto Ruedy, Makiko Sato, Josh Willis, Anthony Del Genio, Dorothy Koch, Andrew Lacis, Ken Lo, Surabi Menon, Tica Novakov, Judith Perlwitz, Gary Russell, Gavin A. Schmidt, Nicholas Tausnev (2005). “Earth’s Energy Imbalance: Confirmation and Implications”. Science 308 (5727): 1431-1435.

  62. jas3
    Posted Jul 6, 2008 at 8:04 AM | Permalink

    Re #65:

    I used to not think rivers had much to do with Global Sea Level Rises, but then I zoomed in ( on these satellite images of dozens of U.S. rivers that emitted more that 100,000 cubic meters/sec of H2O during 2008. Some of these locations released more than 16,200 cubic meters during one second.

    The web site takes a few seconds to load, but once it loads, the speed is fast as you click on the icons in the right-hand column and the map zooms in and gives you a satellite image of these rivers.

    The lesson is that looking only at the SUPPLY side of CO2 production without looking at the DEMAND side tells you nothing at all about the CO2 cycle. Being convinced by pictures of smoke stacks rather than looking at the actual carbon cycle in full and attempting to understand how very very little 100,000 tons of CO2 is in an atmosphere with 720 Gigatons of CO2.

    Instead of looking at pictures, try to understand the quanta behind the carbon cycle.


    p.s. The link for post #65 appears to be an advertisement.

  63. Posted Jul 28, 2008 at 8:39 AM | Permalink

    re 65:

    What makes you say that?? As the sun expels more and more of its material/matter/energy over time, its gravitational pull on the Earth should be less, not more. Therefore, the Earth should move away from the sun. Not that it really matters, as we are talking small amounts here. Eventually the sun will blossom into its giant state, and we will become a charred planet. Hopefully, I’ll be dead by then.

  64. Peter Stroud
    Posted Aug 1, 2008 at 8:56 PM | Permalink

    Interesting paper, thanks and congratulations on its completion.

    As I understand it, CO2 is regarded by some as a positive feedback mechanism along with various forcings it is assumed that temperature will increase at an alarming rate.

    If this is the case then how ever did we get out of the paleozoic period when CO2 concentrations started at 7000ppm.
    Does this not show that CO2 can not be regarded as a positive feedback mechanism.

  65. Posted Sep 6, 2008 at 11:41 PM | Permalink

    Interesting to read through beginning in 2005.

    ‘Tis now Sept 2008, and temperatures have been declining for ten years. (1998 – 2008).

    So we have 1/2 of one degree of “global warming” from 1973 – 1998 (25 years). snip -policy
    This was followed by nine years (1998 -2007) of static, slightly cooling temperatures and one year (so far) of a noticeable decline. – So we are now back to those temperatures about the same as in 1983 – 1986.

    Of course, before that, we had 25 years of “global cooling” of about 0.4 degree from 1945 through 1973, preceded by 30 some-odd years of global warming of about .5 degree from 1890 to 1945..

    Does any one see a pattern here? 8<)

    On a more serious note: If the past 110 years show a thirty cycle of 0.5 degree up-and-down change in temperatures, how can a 1200 year record be developed showing the same scale of change: Can you really expect to see 0.75 degree long-term changes over a 1200 year period (knowing that baseline dates of each year’s record – whether tree rings or any other proxy – are very uncertain) when the short term cycle is also 0.5 degree (or greater?)

  66. OzzyAardvark
    Posted Sep 12, 2008 at 10:25 PM | Permalink

    I honestly don’t know whether AGW is a problem or a myth, but I’m rather certain that some people will live and others will die based on AGW-driven public policy decisions, regardless of which way they turn. Having a transparent discussion on the data is the only way to come to the right (or perhaps the least wrong) policy. People who claim to be a scientific authority but then refuse to share their underlying methodology and data on a subject as important as this are to be held in contempt.

    – a considerable amount of code is available in Mann’s latest paper. Others are much worse and Mann should not be singled out. HAving said that, important issues in the original paper remain unresolved. I’ve snipped since the comments are piling on a bit.

  67. jae
    Posted Sep 12, 2008 at 10:46 PM | Permalink

    Ozzy: Shocking, isn’t it? And it’s all documented fact. Read some more, it’s better than any novel on the best-selling list.

  68. OzzieAardvark
    Posted Sep 16, 2008 at 9:51 PM | Permalink

    @Steve – I’ll leave to your judgment whether my comments are piling on. That said, I simply can’t understand why someone with an important role in the science associated with AGW would choose to not fully share the data and methodology from the research that they’ve done. Being a high-profile scientist is hard. Opening up work that one has sweated over for years to the scrutiny and criticism of others is very difficult in any profession. Even so, in order to be a scientist, one must transparently submit their work to the scientific community for critical evaluation. Equivocating about which member of The Team is somewhat more open than others does little to address the fundamental issue. Humanity has a desperate need for an open and scientifically sound assessment of AGW theory. My reading to date has indicated to me that Mann has not been fully transparent in the presentation of his work in this area. Please correct me if you feel my assessment is wrong – and if this thread isn’t completely dead by now 🙂

  69. m miller
    Posted Dec 9, 2009 at 10:27 PM | Permalink

    Conceivable theory JC. It sounds plausible that such actions did take place.

  70. Fred
    Posted Dec 12, 2009 at 1:58 PM | Permalink

    Regardless of the wonders that smoothing has done for the ~1000-year hockey-stick graph, I am amazed to see what looks like the long term declining trend of the last half of the Holocene period in the (almost) horizontal portion of the graph. Everything else has been obliterated.

    I’m an amateur so please forgive errors.

    : )

  71. Illya kuryakin
    Posted Dec 13, 2009 at 8:46 PM | Permalink

    Perhaps its a natural process to arrive at a state of diminishing returns. None the less I hope that we do not wind up zeroing out funding for climate research to resolve the lean forward on the theory. You are doing a good job to keep the climate research going, at a sustainable level.

  72. Ian H
    Posted Feb 22, 2010 at 9:29 PM | Permalink

    @JC – Paragraphs are your friend.

    I believe that what you are saying is that the climategate story bears many similarities to a classical economic bubble.
    I too have been thinking along these lines.

    In a market bubble there is an underlying reality by which things should be valued but this is changes only slowly by comparison to the pace of the market. So too in climate science the underlying reality (the climate) changes only slowly by comparison to the pace of research and the careers of scientists.

    In a market, short term fluctuations are driven more by the behavior and opinions of other participants in the market rather than by the underlying reality. So too in climate science, scientists are rewarded by earning the esteem of their peers, and this happens over a much shorter timeframe than their predictions can be tested against changes in the climate.

    What you see in both cases is an unstable situation where feedback predominates leading to the existence of bubbles where the market or the science becomes completely detached from reality.

    However I fear both our posts have drifted too far from the original topic of Hockeysticks, and we would be better to continue this discussion in another forum.

  73. William Hayden Smith
    Posted Nov 2, 2010 at 1:28 AM | Permalink

    One oddity of climate averaging just registered with me recently.
    Climate averages are usually given as thirty year running averages, that is, every year, one adds the most recent year’s temperature or other parameter and drops the thirtieth preceding year, to establish a new “running average”. So, short term trends are smoothed out.
    For example, Arctic Ocean ice coverage shows a minimum around 20 September each year. There has been much made of the reduction of ice to a low mimimum in 2007, compared with the average from 1979 to 2000. That interval is only 21 years! See, for the data:( Why average for just 21 years? Presumably, it is because the technique for measurement began in 1979. OK, but then, to be consistent, the running average should extend to 2008, and then begin adding each subsequent year’s ice coverage for comparison, i.e. 2009 and now 2010. A 30 year running average for ice coverage does not show such a “dramatic” loss of ice.
    Since the minimum in 2007, the decrease in ice coverage has stopped and reversed itself. What the future holds for Arctic Ocean ice coverage, one cannot calculate with any certainty, but let us, at least, be consistent and use a 30 year running averages for climate comparisons, not just a convenient time interval to make a desired point look impressive. Averaging 1979-2000, as if this period were a special baseline, has NO basis. As the time line has now extended beyond 30 years, compute a 30 year running average or give a good reason why this is NOT done.

  74. OzJuggler
    Posted Feb 8, 2012 at 11:39 AM | Permalink

    An SkS user called “caerbannog” says that McIntyre doesn’t know how to apply SVD.

    He says:

    The bottom line is, unless you look at the singular values, you can’t say *anything* about your data. You can’t simply look at the principal components (aka singular vectors) without considering the associated singular value magnitudes and draw any reasonable conclusions about whether your data vectors contain a “common signal” or are just random noise. Without the information provided by the singular values, you simply can’t tell (no matter what your principal-components look like).

    But that’s exactly what skeptics did when they attacked Mann by claiming that his procedure generates hockey sticks from random noise. They never bothered to compare their “noise hockey stick” singular values with Mann’s “tree-ring” singular values.

    Could McIntyre respond, perhaps by saying whether this is a red herring argument about the validity of the temperature hockey stick, or whether caerbannog actually has a valid point.

    Steve: In our 2005 GRL article, we comment on “eigenvalues” from simulations as compared to Mann’s. “eigenvalues” are the same thing as “singular values”. Not that the issue turns entirely on eigenvalue significance. The bristlecones in the AD1000 network are “significant” even without Mann’s erroneous PC method – a point made in our 2005 EE article. That doesn’t mean that they are magic thermometers. Other important issues in these articles are the failure of verification statistics said to have been used in MBH (verification r2) and the unreliability of RE as an arbiter of reconstruction validity in the face of spurious correlation.

    • William Hayden Smith
      Posted Feb 8, 2012 at 1:00 PM | Permalink

      As a user of SVD methods, I can answer generically the questions posed by OzJuggler.
      In a scene, the number of components that can be resolved depends upon the spectral contract (variability) and the signal-to-noise (S/N)of the measurements. The more structure in the spectrum and the higher the S/N in the data, the more components can be distinguished in the data. So far, so good.
      For example, a terrestrial scene compared with an ocean scene for the same S/N (assuming the S/N is high and not near unity) has more distnguishable components since the spectral contrast is always higher, or put another way, water completely dominates the ocean scene, as you might expect.
      Tree ring data, along with other climate proxies, has a fundamental problem. The spectral contrast (ring variability) arises from multiple causes. SVD assumes an orthonormal basis set, and as a result, picks out the optimum basis for decomposition, which is NOT simply temperature, precipitation or other climate variables. Nonetheless, the observations ARE interpreted without KNOWING what the S/N is with regard to the climate parameters being evaluated. The proxy may show correlation but through what parametrization with regard to the climate is not known. One HOPES the basis vectors are known climate parameters such as temperature, precipitation, mean wind fields, insect infestatios, or other known components. Forcing the basis set to BE well defined climate components and then extracting the principle components will always achieve a best fit, but uniqueness does not exist.
      Put succinctly, SVD assumes you KNOW the correct orthonormal basis upon which to decompose the measurements, which you never do. So, SVD must be taken with a LARGE grain of salt, however it is used. If a scene has only two or three major components, and you extract some vectors from SVD which resemble the expected components, then the agreement makes you feel good, but since it is not unique, I would not bet my house on it either way.

      • Bernie
        Posted Feb 29, 2012 at 5:35 PM | Permalink

        I assume that you are saying SVD methods are not very useful data exploration tools when you do not have well defined underlying processes and a very restricted data set. Apparent significant factors can emerge simply by chance with no or spurious relationships to the phenomena being explored.

    • OzJuggler
      Posted Feb 11, 2012 at 5:48 AM | Permalink

      Steve, sorry but that doesn’t really seem to answer the question. In the GRL paper your own diagram shows the example red noise hockey stick is 10 times smaller in scale than the final MBH98 hockey stick. The example was constructed from noise profiles with the same magnitude as the real data because they were based on the real data’s autocorrelation function, yes? And on top of that you divide the series (noise and real) by their SD because the PCA is made more robust by using normalised values, yes? Well the red-noise contrivance produced a hockey stick shape, but not The MBH Hockey Stick magnitude. Therefore “The Hockey Stick” (in both size and shape) was not an artefact only of the technique, so it must be inherent in the tree data. How is that not a fair judgement?

      Steve: the MBH PC1 has EXACTLY the same scale as the synthetic PC1s. This is necessarily so because of how singular value decomposition works. The scale of both gets converted to degrees in the regression phase. There has been considerable disinformation about this from critics of ours, but you’ll notice that neither Mann himself nor wahl and Ammann raised this particular criticism.

      I’ve read Ross’s description so I understand how the freak trees were amplified.
      Is it fair to say the only reason The Mann Hockey Stick was not produced from noise is because no noise sequence had randomly produced a freak late 20th century growth spurt in any series that was fast enough to be exaggerated to that scale?
      If you put a single freak Sheep Mountain tree into the rest of the hundreds of noise samples you used, do you get the no-trend PC suddenly convert into the MBH98 icon?

      Steve: Mannian PCs are a very biased methodology. If you put a couple of HS-shaped series into a series with a different signal, you will get a HS. See our Reply to VZ.

      Surely the physical reasons (eg the Divergence Problem) are a much greater reason to reject the MBH hockey stick than the statistical reasons (eg- the slight effect of non-standard centering and non-standard PC thresholding) ?

      Sorry if this is old ground, but I’ve been a climate skeptic for many years and am only now hearing that some of the things I’ve been told over the years may not be the whole story. If this has been answered already in the intervening 7 years, just show me the thread.

      Steve: if you read our articles rather than secondary sources, you’ll see that the red noise argument, though it attracted a lot of attention, is only one of several important criticisms. In retrospect, I would have placed additional weight on questions and issues arising on application of principal components (of any type, not just Mannian incorrect principal components) to tree ring networks. I look attentively at criticisms of our position and none to date have undermined our points. There’s a great deal of disinformation. I would have expected specialists in the field to be understand the criticisms better than they have and have become a bit bored with what seems to be wilful obtuseness.

      • William Hayden Smithw
        Posted Feb 11, 2012 at 8:41 AM | Permalink

        SVD analysis is a mathematical tool for extracting information consistent with a data set. An answer is found, even if the data set is flawed. The main difficulty with the hockey stick is that it is not consistent with most other independent data sets. Other tree ring data, 10 Be data, orbital satellite data, borehole data, ice coring data, etc. show, for example, the lengthy medieval warming which is practically absent from the hockey stick. The tight correlation of the hockey stick with CO2 increase is largely absent as well. Every data set shows some warming. For example, the borehole data show warming since about 1500 AD which clearly was not anthropogenic, and in the latest decade, since the very warm 1998, the temperature trend is downward even in the Hadley Center compilations; the most ardent supporters of anthropogenic global warming. Ocean levels have fallen, arctic ice has increased, and so on. So, what was predicted is not consistent with the on-going observations of global climate.

  75. theduke
    Posted Feb 29, 2012 at 3:21 PM | Permalink

    Looks like the LA Times has hired Joe Romm to head their Opinion staff:

    • Skiphil
      Posted Dec 8, 2012 at 3:47 PM | Permalink

      AGU political leadership seems dominated by the Romm/Mann school of hype.

      It would be interesting to know how long insiders maintained the view that Gleick’s misbehavior has “ravaged his reputation” (Romm’s phrase at linked book review), since it is still 2012 and Gleick/Mann seem to be at the peak of their reputational currency in many AGU circles.

16 Trackbacks

  1. […] if you are as interested in being right as you are in trying to make me believe that I am wrong: Climate Audit – by Steve McIntyre » McKitrick: What the Hockey Stick Debate is About? As for credentials mattering, I would hold suspect any scientific analysis on the climate that is […]

  2. […] if you are as interested in being right as you are in trying to make me believe that I am wrong: Climate Audit – by Steve McIntyre » McKitrick: What the Hockey Stick Debate is About? As for credentials mattering, I would hold suspect any scientific analysis on the climate that is […]

  3. By Niche Modeling » Evidence Based Practise on Jun 9, 2008 at 9:48 PM

    […] to human emission. This view on historic temperatures, particularly in the Medieval Warm Period, has been reversed by a number of more rigorous studies. At best, one could say that some of these studies sit at […]

  4. […] I think that climate scientists have proven with their bad science that they are not up to the task. I wonder if Pennsylvania has a similar law to address Dr. Mann’s scientific shenanigans? […]

  5. […] number. It was they who exposed the deficiencies of the IPCC study that gave rise to the infamous hockey-stick graph, which obliterated the medieval warm period and the little ice age which followed. Essex and […]

  6. By Fear and Loathing in Global Warming on Nov 21, 2009 at 1:39 AM

    […] backstory here begins with some brave amateur sleuths led by Steve McIntyre who first debunked the Mann Hockey Stick, the linchpin of the GW argument. Then they debunked the attempt to resurrect the hockey stick. […]

  7. […] hvordan jordens temperatur har vært relativt lav frem til ca år 1900, hvor den stiger enormt mye. Steve McIntyre og Ross McKitrick kritiserte hvordan Mann hadde brukt proxyer, dvs variable som skal bevise […]

  8. […] third IPCC report (2001) DID NOT!!!  It replaced the graph with the now infamously debunked ‘hockey stick graph’… and claimed the 1990’s were by far the warmest period […]

  9. By Klimatpanelen mitt i stormen « on Mar 28, 2010 at 8:43 AM

    […] finns det forskare som inte är lika säkra på att det är koldioxiden som är den stora boven, att det finns andra orsaker till den klimatpåverkan vi har idag. Människan har naturligtvis […]

  10. […] public accountability of the research.   The response of the climate researchers to McIntyre and McKittrick, by attacking their qualifications and motives rather than trying to work with them or at least […]

  11. […] […]

  12. […] I used to believe in man-made global warming. Then I found out that there was another side to the story and I was shocked. The good name of science is being exploited. Over $79 billion dollars has been fed into one side of a scientific question, while almost none has been put into auditing the reports, checking the results, or investigating other theories. (Which National Institute do climate skeptics apply for a job at? Answer: None.) We paid to find a crisis, and we got what we paid for. Thousands of skeptics are working pro bono because they are outraged. Retired scientists and engineers and teams of helpers are independently auditing official reports. They are busting major peer reviewed papers. […]

  13. By Hide the Decline – igen | The Climate Scam on Mar 25, 2011 at 6:10 PM

    […] kritiserades hårt och framgångsrikt av matematikern och gruvingenjören Steve McIntyre och ekonomiprofessorn […]

  14. […] skeptics going through the process of trying to replicate the results of climate scientists.  Steve McIntyre is one of those that tried to replicate the results of Dr. Mann who produced the hockey stick and […]

  15. […] The first controversy, “hiding the decline” is related to an attempt to create a global temperature record by Dr Michael Mann of Penn State, who used records of tree-cores collected at a handful of sites across the world to create a historical temperature record. By measuring the density and thickness of the rings, one can create a record going back about a thousand years of tree growth. Dr Mann used a statistical process that is a variant of Principal Component Analysis to generate identify which sets of tree-cores had growth patterns that most closely tracked temperature in the past hundred years. He presumed that these sets of cores would maintain a similar relationship with temperature throughout the entire record. By mathematically applying this transformation to the tree-core data, he produced the thousand year reconstruction known colloquially as the Mann Hockey Stick, which played a central role in both IPCC reports and in Al Gore’s movie, and Inconvenient Truth. At this point, I should digress to explain several critical flaws in Michael Mann’s work that doom this effort. […]

  16. By Science or political sophistry? | Squall Lines on Jun 13, 2012 at 11:55 AM

    […] there is no “settled science” on the theory of global warming. (link) In international surveys of hundreds of climate scientists “…half the scientific community […]

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