Why was the Hockey Stick Graph so Important?

Discussion in 'Environment' started by IanC, Mar 30, 2011.

  1. IanC
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    IanC Gold Member

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    because it got rid of the Medieval Warm Period and to a lesser degree the Little Ice Age.

    why is that so important? science couldnt explain why the MWP happened using known natural variables. if they didnt have to admit they didnt understand the reasons for that warm period then they could turn the null hypothesis on its head in the 20th century and say that known factors cant explain the present age warming so it must be CO2!

    it was clear that the first and second IPCC reports understood that there were large gaps in understanding the mechanisms that control climate. since the 2001 report and Mann's graph they have not been forthcoming about their ignorance.

    we know that Mann's Hockey Stick was pseudoscience and an affront to the scientific method but the damage has been done. it created a paradigm of using CO2 as the scapegoat and climate models as data.

    I have no idea how we can rehabilitate the reputation of climate science but having a real investigation into Climategate would be a good start.
     
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  2. Old Rocks
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    Old Rocks Diamond Member

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    The Hockey Stick Graph has been redone many times since the original. And, while the revisions now show a couple of periods of warming, nothing approachs the warming that we are seeing at present. The National Academy of Sciences did a study of the Mann's methods and statistical analyisis. Using their own and his data, and their own statistical methods, their graph said the same as Mann's original one. In fact, that is the case for every honest study that has been done on that graph.

    Much-vindicated Michael Mann and Hockey Stick get final exoneration from Penn State — time for some major media apologies and retractions « Climate Progress
     
  3. Oddball
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    Oddball BANNED Supporting Member

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  4. IanC
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    IanC Gold Member

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    ah yes. the Penn St investigation. in depth and very thorough wasnt it?
    of course Mann did send the request to delete FOIA covered emails to Wahl, and Wahl did delete the emails. but Penn State didnt ask Wahl anything. why would they, lol.

    as far as the later versions of the Hockey Stick, they have the same problems with hidden truncations, use of out of date data sets, use of unsuitable data (one set of cores was actually used upside down!!!), unsuitable statistical methods, and lack of validation (remember that r2 value that Mann had to calculate out to 5 decimal places just so he didnt have to say it was zero?).

    if you think Mann and his work are vindicated then you have overdosed on the kool-aid
     
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  5. skookerasbil
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    skookerasbil Gold Member

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    fAiL s0n........the whole world thinks that "exoneration" is doctored.

    The hockey stick myth died long ago............


    The proof s0n..............oh, I know it stings!!!





    Only 33% Think Most Americans Blame Humans for Global Warming

    Thursday, March 24, 2011

    Only 33% Think Most Americans Blame Humans for Global WarmingThursday, March 24, 2011



    [​IMG]
     
    Last edited: Mar 30, 2011
  6. wirebender
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    wirebender Senior Member

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    Do you actually believe any of what you write or are you like one of Pavlov's dogs who simply reacts in a pre programmed fashion to any statement that you see in opposition to what you have been told? The FACT is that The National Academy did not exonerate Mann's methods. Have you ever actually read their statements regarding their findings on Mann's methods? Here, have a look:

    1. The NAS indicated that the hockey stick method systematically underestimated the uncertainties in the data (p. 107).

    2. In subtle wording, the NAS agreed with the M&M assertion that the hockey stick had no statistical significance, and was no more informative about the distant past than a table of random numbers. The NAS found that Mann's methods had no validation (CE) skill significantly different from zero. In the past, however, it has always been claimed that the method has a significant nonzero validation skill. Methods without a validation skill are usually considered useless. Mann’s data set does not have enough information to verify its ‘skill’ at resolving the past, and has such wide uncertainty bounds as to be no better than the simple mean of the data (p. 91). M&M said that the appearance of significance was created by ignoring all but one type of test score, thereby failing to quantify all the relevant uncertainties. The NAS agreed (p. 110), but, again, did so in subtle wording.

    3. M&M argued that the hockey stick relied for its shape on the inclusion of a small set of invalid proxy data (called bristlecone, or “strip-bark” records). If they are removed, the conclusion that the 20th century is unusually warm compared to the pre-1450 interval is reversed. Hence the conclusion of unique late 20th century warmth is not robust—in other word it does not hold up under minor variations in data or methods. The NAS panel agreed, saying Mann’s results are “strongly dependent” on the strip-bark data (pp. 106-107), and they went further, warning that strip-bark data should not be used in this type of research (p. 50).

    4. The NAS said " Mann et al. used a type of principal component analysis that tends to bias the shape of the reconstructions", i.e. produce hockey sticks from baseball statistics, telephone book numbers, and monte carlo random numbers.

    5. The NAS said Mann downplayed the "uncertainties of the published reconstructions...Even less confidence can be placed in the original conclusions by Mann et al. (1999) that ‘the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium.’

    Combine those findings with the fact that there is, at present, data published by over 900 scientists representing over 500 research institutions from over 40 countries that support the statement that the Medieval Warm Period was both warmer than the present and global in nature and one must either pity, or laugh out loud at your continued defense of such a charlatan.
     
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  7. Old Rocks
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    Old Rocks Diamond Member

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    OK, Bender, you had your say. Now why didn't you bother to post the link to the NAS site? Could it be because what you posted in no way is what the NAS report stated? Uncertainties, yes, but the NAS data fully supported Mann.

    http://dels.nas.edu/resources/stati...orts/reports-in-brief/Surface_Temps_final.pdf

    Surface Temperature Reconstructions for the Last 2,000 Years

    The basic conclusion of Mann et al. (1998,
    1999) was that the late 20th century warmth in
    the Northern Hemisphere was unprecedented
    during at least the last 1,000 years. This conclusion
    has subsequently been supported by an
    array of evidence that includes both additional
    large-scale surface temperature reconstructions
    and pronounced changes in a variety of local
    proxy indicators, such as melting on icecaps and
    the retreat of glaciers around the world, which in
    many cases appear to be unprecedented during
    at least the last 2,000 years. Not all individual
    proxy records indicate that the recent warmth is
    unprecedented, although a larger fraction of geographically
    diverse sites experienced exceptional
    warmth during the late 20th century than during
    any other extended period from A.D. 900 onward.
    Based on the analyses presented in the original
    papers by Mann et al. and this newer supporting
    evidence, the committee finds it plausible that
    the Northern Hemisphere was warmer during the
    last few decades of the 20th century than during
    any comparable period over the preceding millennium.
    The substantial uncertainties currently
    present in the quantitative assessment of largescale
    surface temperature changes prior to about
    A.D. 1600 lower our confidence in this conclusion
    compared to the high level of confidence
    we place in the Little Ice Age cooling and 20th
    century warming. Even less confidence can be
    placed in the original conclusions by Mann et
    al. (1999) that “the 1990s are likely the warmest
    decade, and 1998 the warmest year, in at least a
    millennium” because the uncertainties inherent in
    temperature reconstructions for individual years
    and decades are larger than those for longer time
    periods, and because not all of the available proxies
    record temperature information on such short
    timescales.
     
  8. konradv
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    konradv Gold Member

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    Hockey stick, schmockey stick. The bottom line is, knowing GHGs trap infra-red radiation, warming is inevitable, if the rising trend of their concentrations, seen since the advent of the Industrial Revolution, continues. Argue all you want about temps and models, I have seen no attempt to show what I said to be false, just misdirection and distractions from the logic impaired. So the hockey stick graph wasn't perfect. Initial stabs at new lines of research rarely are. Over time, with more data most of those problems will clear up. What doesn't seem to ever clear up is the deniers' refusal to face the basic facts concerning the scientifically well-documented properties of GHGs!!!
     
  9. wirebender
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    wirebender Senior Member

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    Until I have more posts, I can't post to any site. That asied, the facts don't support man. As I sated, more than 900 scientists representing more than 500 research institutions from over 40 countries have published papers that overwhelmingly support the statement that the Medieval warm period was both warmer than the present and global in nature. Since mann's hockey stick doesn't reflect the observed data, it is clear that it is a fraud.

    As far as your claim that the NAS vindicated mann, perhaps you are unaware of the fact that after Wegman thoroughly debunked mann and his hockey stick as no more and no less than bad math, Gerald North (chairman of the NAS panel that according to you gave mann the thumbs up on his methodology and findings) when asked whether or not the NAS agreed with Wegman's harsh findings, he said that they did.

    CHAIRMAN BARTON: Dr. North, do you dispute the conclusions or the methodology of Dr. Wegman’s report?

    DR. NORTH [Head of the NAS panel]: No, we don’t. We don’t disagree with their criticism. In fact, pretty much the same thing is said in our report.

    DR. BLOOMFIELD [Head of the Royal Statistical Society]: Our committee reviewed the methodology used by Dr. Mann and his co-workers and we felt that some of the choices they made were inappropriate. We had much the same misgivings about his work that was documented at much greater length by Dr. Wegman.

    WALLACE [of the American Statistical Association]: ‘the two reports [Wegman's and NAS] were complementary, and to the extent that they overlapped, the conclusions were quite consistent.’

    You do yourself no credit trying to support a fraud.
     
  10. skookerasbil
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    skookerasbil Gold Member

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    Rocks s0n......now you got even more guys in here pwning your BS!!! Wire took a gandor in here and decimated your shit.


    I hear this site has an ENVIRONMENTAL forum!!!!

    Jackass.com
     

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