Oh Mann! Paper demonstrates that tree-ring proxy temperature data is ‘seriously compromised’

Michael Mann won’t be happy about this.

A new paper now in open review in the journal Climate of the Past suggests that “modern sample bias “has “seriously compromised” tree-ring temperature reconstructions, producing an “artificial positive signal [e.g. 'hockey stick'] in the final chronology.”

Basically, older trees grow slower, and that mimics the temperature signal paleo researchers like Mann look for. Unless you correct for this issue, you end up with a false temperature signal, like a hockey stick in modern times. Separating a valid temperature signal from the natural growth pattern of the tree becomes a larger challenge with this correction.

Here is a relevant excerpt:

Much of the work in dendrochronology, and dendroclimatology in particular, relies on accurate, unbiased reconstructions of tree growth long into the past. As a result, a great deal of effort has been put into trying to isolate important trends and identify potential 5 biases. However, one major bias called “modern sample bias”, first identified by Melvin (2004), is still largely neglected in applied studies, despite its potential impact on all regional curve standardization chronologies (Brienen et al., 2012a).

Dendrochronologists observed that the older a tree was, the slower it tended to grow, even after controlling for age- and time-driven effects. The result is an artificial downward signal in the regional curve (as the older ages are only represented by the slower growing trees) and a similar artificial positive signal in the final chronology (as earlier years are only represented by the slow growing trees), an effect termed modern sample bias. When this biased chronology is used in climate reconstruction it then implies a relatively unsuitable historic climate. Obviously, the detection of long term 15 trends in tree growth, as might be caused by a changing climate or carbon fertilization, is also seriously compromised (Brienen et al., 2012b). More generally, modern sample bias can be viewed as a form of “differing-contemporaneous-growth-rate bias”, where changes in the magnitude of growth of the tree ring series included in the chronology over time (or age, in the case of the regional curve) skew the final curve, especially 20 near the ends of the chronology where series are rapidly added and removed (Briffa and Melvin, 2011).

A likelihood perspective on tree-ring standardization: eliminating modern sample bias

J. Cecile, C. Pagnutti, and M. Anand
University of Guelph, School of Environmental Sciences, Guelph, Canada

Abstract

It has recently been suggested that non-random sampling and differences in mortality between trees of different growth rates is responsible for a widespread, systematic bias in dendrochronological reconstructions of tree growth known as modern sample bias. This poses a serious challenge for climate reconstruction and the detection of long-term changes in growth. Explicit use of growth models based on regional curve standardization allow us to investigate the effects on growth due to age (the regional curve), year (the standardized chronology or forcing) and a new effect, the productivity of each tree. Including a term for the productivity of each tree accounts for the underlying cause of modern sample bias, allowing for more reliable reconstruction of low-frequency variability in tree growth.

This class of models describes a new standardization technique, fixed effects standardization, that contains both classical regional curve standardization and flat detrending. Signal-free standardization accounts for unbalanced experimental design and fits the same growth model as classical least-squares or maximum likelihood regression techniques. As a result, we can use powerful and transparent tools such as R2 and Akaike’s Information Criteria to assess the quality of tree ring standardization, allowing for objective decisions between competing techniques.

Analyzing 1200 randomly selected published chronologies, we find that regional curve standardization is improved by adding an effect for individual tree productivity in 99% of cases, reflecting widespread differing-contemporaneous-growth rate bias. Furthermore, modern sample bias produced a significant negative bias in estimated tree growth by time in 70.5% of chronologies and a significant positive bias in 29.5% of chronologies. This effect is largely concentrated in the last 300 yr of growth data, posing serious questions about the homogeneity of modern and ancient chronologies using traditional standardization techniques.

The full paper is here: http://www.clim-past-discuss.net/9/4499/2013/cpd-9-4499-2013.pdf

h/t to The Hockey Schtick

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112 thoughts on “Oh Mann! Paper demonstrates that tree-ring proxy temperature data is ‘seriously compromised’

  1. I’m not clear as to how this works. For example, the ring pattern of twenty-year-old trees would be unaffected by this effect no matter what year their seed sprouted… are they proposing that modern trees tend to be younger trees than the average of sampled trees? Why would this be so?

  2. There are so many factors affecting tree Growth that it’s ideal for policy based science? What ever you want to produce you will find it if you search enough?

  3. Fer chrissake, dendrochronology is rife with assumptions and bias sources….wait for it….like a model! OK, so old trees grow more slowly. How much of a correction do we apply? And which one? Bob’s? Mike’s? Eddy’s? Jennifer Juniper’s? For there to be so much egomaniacal buffoonery over whose DC record is the most ‘robust’, whose derobustification correction was applied to the quasi-robust records to rule them out? While all of this makes stimulating reading, especially when we find a paper that bashes ol’ Mann, does any of it really mean anything, or is it just more make-it-fit-the-assumption trainwreck detritus? The fact that there’s a journal ‘Climate of the Past’ suggests that it’s an important branch of climate druidity, but whose correction got applied? Watching Mann defend his smarmy position is bad enough, but now we have an out-and-out display of just how flawed the whole exercise is. A black hole for funds.

  4. All you can tell from tree rings is whether the environment round that tree was favourable (or not) to that tree’s growth. The amount of rain, sunlight and nutrients (including ppCO2) available to the tree will be as much of an influence on its growing rate as the prevailing temperature.

  5. >>Unless you correct for this issue, you end up with a
    >>false temperature signal.

    But will you end up with a temperature signal at all? Here are a few scenarios for you…

    a. Tree experiences a very cold summer, with no growth. (a temperature signal?)
    b. Tree experiences a very hot but too dry summer, with no growth. (a temperature signal?)
    c. Tree experiences a cool but nicely moist summer, with good growth. (a temperature signal?)
    d. Tree experiences a very hot and wet summer with good growing conditions but a rampant pest infestation, with no growth. (a temperature signal?)

    Just what are they measuring, when looking at tree rings? Temperature? Moisture? Infestations? Micro-climates? Forest canopy competition?

    .

  6. This is well known to foresters. Young trees have a rapid growth which is reflected in wide growth rings,which continue until limiting factors kick in. These could be light, moisture stress, nutrient availability. Different species have different growth rates, eg, Birch is relatively short lived reaching maturity in as little as 70-80 years, whereas with Oak, it is several hundred years. As the trees move through Juvenile to mature their growth rate slows, much like everything else i suppose. In commercial forestry, to maximise returns, harvesting is timed to occur after the fastest accumulation in volume, which can be as little as 40 – 50 years for Spruce. This of course depends on the end market specifications.
    I would point out that dendrochronology is useful in its primary purpose as a tree-timescale-indicator, but its torturing into making up temp series, without proper recognition of the impacts of the restriction of water, nutrients, access to light and the potential for human impact, thinning, grazing(and therefore manure enrichment) etc is a step too far.

  7. And I will say this again…

    If tree rings are actually measuring micro-climates, micro-moisture content, micro-canopy-competition, and micro infestations, then how on earth can dendro-chronology work?

    Yes, your bristle-cone pine tree ring analysis may sort-of mimic the climatic record. However, your wood sample for dating was grown in a completely different location with completely different local conditions – with local weather, local pests, local water sources and local canopy cover. How on earth is your wood sample going to be an equivalent of the bristle-cone reference sample? And if it is not an equivalent, then how can you derive a date from the width of its rings?

    .

  8. So to summarize it appears the volume of the tree ring might be a more useful measure than the width

  9. “Of course I pre-adjusted for all these supposed faults. Do you take me for a fool?” MM

    “No, you cannot see my code and methodology. You probably just want to pick holes in it. I have stored it all in the ‘censored’ folder. You are not a climate scientist.” Same Guy.

  10. to measure temperature you need a thermometer, not a tree ring…when does a tree ring measure the temperature ? in January, May, or September ? in the morning, afternoon, or midnight ? Proxies are rubbish.

  11. The volume of two rings of equal width will be different: the outer (later) one is longer (larger diameter), with more mass. Conversely, if two rings have the same mass, the outer one will be narrower.

  12. @Leo Morgan

    I’m not a dendrochronologist so I don’t know details, but I can easily imagine that trees from more than 300 years ago might disproportionally rot from the outside inwards, destroying the latest 20 years of growth rings. So maybe 20 year old trees are never found to sample from that long ago.

  13. So, climate and enviroment affects tree ring width/thickness, which is old school knowledge, also time/age is an important factor. Good years with old trees gives thin rings, that can be interpreted as harsh years, vice versa and all in between, if not careful or deliberate …

    Tree rings = circular evidence ? ;-)

  14. Tree rings are perfectly accurate to tell the age of a tree, or the age that a tree died, every thing else is mysticism, the druids would be proud.

  15. I’m not quite sure which way this modern sample bias would affect chronologies, up or down, or more or less hockey stickiness.

    The MBH98 hockey stick treated Graybill and Idso 1993 as a treemometer, but the main purpose of the bristlecone pine paper was to document CO2 fertilization, not temperature. They explicitly stated that there was a lack of strong, consistent temperature response in the subalpine chronologies, and that while there may be some temperature signal pre the mid-1800’s, the signal becomes obscure with the increase in CO2.

  16. Not entirely clear what is being stated here (other than that using tree rings to determine temperature trends is perhaps a fool’s errand).

    Old trees were young once, so they would’ve had the same rate of growth in their early years as modern trees would in their own early years, all other things being equal. What I think is being suggested is that long-lived trees are more likely to be the ones that grow more slowly than the ‘average’ tree throughout their lives. Think of it as the slow-moving Galapagos tortoise versus the scurrying mouse.

    While the sample of modern trees will include some that are destined for a long life and are therefore growing slowly (and would be discarded from the sample by the Team…), the suggestion seems to be that there will also be many faster-growing, shorter-lived trees. By definition, there wouldn’t be any of this type of tree among the 700-year-old trees. Therefore, the average growth rate according to a study sample would be slower in the past and faster in the present.

    That would make sense to me, but I’m not totally clear that is what is being said in this paper.

  17. “Much of the work in dendrochronology, and dendroclimatology in particular, relies on accurate, unbiased reconstructions of tree growth long into the past. ”

    Dendrochronology means measuring time (chronology) or establishing a time-scale using tree rings. This does not require knowledge, detailed or otherwise of past growth rates, it requires counting rings and matching patterns.

    This a precise and well established science.

    There is a wilful attempt by many involved in dendroclimatology and particular dendrothermometry to confound all these terms in the hope that unscientific attempts to use trees as thermometers will get a free pass and be granted the hard-earned credibility of dendrochronology.

    Unfortunately the authors of this paper , while doing a valuable job of pointing out the fallibility of dendrothermometry are tacitly accepting this abuse of the term dendrochronology as encompassing anything done with a tree.

    It is time this abuse of the reputation of dendrochronology stopped and those that want to do dendrothermometry set out to prove it to be a valid method without falsely relying on the credibility of another branch of science.

  18. Tree rings are being used to estimate past temperature, as are sediments and ice cores. Although there are known accuracy problems, I don’t think that tossing out all tree ring proxies is the way forward. This paper, if the science and statistics are sound (I am not one to judge), takes a step forward in improving the accuracy of the proxies. I am eager to see what the paleo temperature record looks like after the changes suggested in this paper are incorporated. If Dr. Mann is the scientist that he claims himself to be then he should be foaming at the bit to incorporate this new method into his next paper, regardless of the political implications that come from the results. Too idealistic?

  19. Just one more reason that there can never be a scientific concensus on climate. There are far too many contributing factors. Those that have “already decided” are the true deniers, as the true science of the Earth is not just mysterious, but ever changing.

  20. “Unless you correct for this issue, you end up with a false temperature signal, like a hockey stick in modern times.”
    So show the correction and find a better description of reality – being the ‘hockeystick’, of course.

  21. I have followed, to date, publications Håkan Grudd’s (http://hakangrudd.blogspot.com/p/publications.html).

    In the last two sentences are those:
    “Uncertainty in the reconstructions is estimated by combining the uncertainty in mean tree growth with the uncertainty in the regression models. Over the last seven centuries the uncertainty is < 4.5% higher than in the 20th century, and reaches a maximum of 12% above recent levels during the 10th century.”
    “The results suggest that the 20th century was the warmest of the last 1200 years, but that it was not significantly different from the 11th century.” (second to last).
    “The use of 'growth-rate' based multiple RCS curves is recommended to identify and mitigate the problem of 'modern sample bias'.”
    “The new MXD and TRW chronologies now present a largely consistent picture of long-timescale changes in past summer temperature in this region over their full length, indicating similar levels of summer warmth in the medieval period (MWP, c . ce 900–1100) and the latter half of the 20th century.” (last – intentionally I moved the sequence sentences).

  22. Question given the high reliance on trees and there growth , how many of ‘the Team ‘ are actual experts in this area , whose background gives them a good understand of ‘tree growth ‘
    Answer , none but this does not stop them being able to make absolutists statements on this subject and attacking others , some with more knowledge than them , for failing to agree with them.
    Arrogance, massive ego , hubris are the three thing s that will never be lacking in this area no matter how bad the shortfall in scientific ability and honest gets .

    It’s really basic stuff that your data is only ever as good as the tool you use to collect it, that this ignored by those ‘leaders’ of this area . Which tell us a great deal about the standards seen in this area.

  23. J. Cecile, C. Pagnutti, and M. Anand will be unceremoniously kicked out of the consensus, in spite of the fact that they got to the “root” of the problem.

  24. Not a long ago M. Mann claimed he discovered the AMO, or at least the name for something which was already known.
    As far as Yamal is concerned, he could have done more convincing job if he compared natural geomagnetic changes there with the Atlantic Oscillations as shown here :

    http://www.vukcevic.talktalk.net/YAMAL-GMF-AMO.htm

    Unlikely to be coincidence, since it is known that the AMO is related to the volume ice flow through Fram Straits etc.. (see link above).

  25. Unless I missed something, I scanned the paper and saw no reference to Yamal YAD061:

    There are lots of complicated, fancy formulas, which are way over my head, but isn’t the crux of the matter (the Mann hockey stick) – is that it is based on this one tree?
    Am I missing something here?

  26. There are simply too many variables involved to use the width of tree rings alone as a proxy for anything other than the general (but important) concept of “growth,” and “growing season.”

    There is some prospect of learning more specific things through the painstaking process of taking tiny samples from each ring, and studying the chemistry and radioactive isotopes of each ring.

    Unfortunately political bullying and balderdash has so blotched dendroclimatology that it will take time to recover. There is little dignity in being part of a “tree-ring-circus.”

    However “dendroclimatology” remains a cool word to casually use at a cocktail party. Much cooler than “looking at the rings.”

  27. Greg says:
    August 16, 2013 at 3:04 am

    It is time this abuse of the reputation of dendrochronology stopped and those that want to do dendrothermometry set out to prove it to be a valid method without falsely relying on the credibility of another branch of science.
    ============================================
    That sums it up pretty well. AFAICS Dendrothermometry is in roughly the state that Phrenology had reached by the early 19th century when there were numerous bright people trying to determine the relationship between cranial bumps and other human characteristics. There were Phrenology societies and journals publishing learned papers. By the 1840s Phrenology was fading. It simply didn’t work.
    I suspect that Dendrothermometry may have a little more to offer than Phrenology. But maybe not a lot. The claims made for it strike me as being mostly being motivated by folks who can torture tree ring data into yielding the answers they want to see. “C’est magnifique, mais ce n’est pas la science.”

  28. Is there a similarity with ice core dating, where very young core parts cannot used if they are still firn? Does the present firn property influence ice core selection of test areas in way similar to that proposed in the paper for trees? What can be deduced from a core whose firn sometimes melts before compaction, leaving a thinner ring or an occasional series of no rings?

  29. It appears to me that actual scientists have decided to look into dendroclimatology.

    The tea-leaf readers ought to be looking into what phrenologists did for a living after they were found out. Could well inform their career decisions going forward.

  30. Do I have this right? Trees make very poor temperature proxy for several reasons and a large portion (>50%) of temperature paleo data is based on tree rings. High CO2 sensitivity calculations are based on paleo data. Therefore high sensitivity calculations are highly uncertain.

  31. In the tree ring growth chemistry, is it possible to find a difference between cold growth/wet growth/dry growth/hot growth. Look up, there’s grant money here!

  32. The paper’s conclusions suggest that this is a clever way to hide the decline by adjusting it rather than erasing it.

    “Contrary to prevailing opinion (Brienen et al., 2012a), modern sample bias does not always impart a positive bias on the standardized chronology but depends instead on the complex ecological interactions dictating survival and the vagaries of sampling. In fact, in 70.5% of the chronologies analysed, it had a negative effect instead.”

    “D’Arrigo et al. (2008) suggest that modern sample bias may be responsible for the
    “divergence problem” in dendroclimatology, the widespread reduction in temperature sensitivity of tree-ring chronologies in recent decades. The generally negative trend induced by modern sample bias in recent years certainly suggests that this may be at least part of the problem.”

  33. Another good example of non experts in the basic source of the data – forestry knowledge happily boring holes in trees and measuring rings. It seems from comments, that foresters already knew that mature tree growth slows down. Rapid root development slows down, the area of canopy exposed to the sun gets constrained by neighbors’ competition, water resources more and more competition, nutrients in the soil lesser (trees can’t walk around. Wow and I’m only an engineer.

    Now what would an engineer do. Note the general narrowing of the rings and asking what could cause this. Most of these possibilities have been answered in above posts and maybe I made a small contribution in paragraph#1. It’s clear if you are LOOKING FOR A TEMPERATURE SIGNAL, and you are a dummy about the actual botany of a tree, then other possibilities don’t interfere with your work.

    Now how could an engineer discover this new finding if contracted to do so. Why, by drilling holes in a few dozen older trees and a few dozen younger trees in the juvenile stage and doing a statistical analysis of the difference in ring thickness for the same years. I haven’t read the paper so I’m not sure yet how they did it, but it must be something like this. Possibly also measuring the exposed leaf area of trees of various ages might give supplementary info.

    Now perhaps, from this, my discovery of the reason for the “divergence problem” the GACS (golden age climate scientists) have much mused over.

    http://en.wikipedia.org/wiki/Divergence_problem

    Alas, history will record some other guy’s name for this discovery.

  34. J. Philip Peterson says:
    August 16, 2013 at 4:45 am
    “Unless I missed something, I scanned the paper and saw no reference to Yamal YAD061:

    There are lots of complicated, fancy formulas, which are way over my head, but isn’t the crux of the matter (the Mann hockey stick) – is that it is based on this one tree?”

    Yeah but by using one tree you don’t get conflicting data so that has to count for something.

  35. So all those guesstimates of multidecadel climate cycles like the PDO & NAO that are invariably based on tree ring proxys are also rendered uncertain.

    Of course the fact that every other method of deriving past temperature from geological or biological proxys (boreholes, corals sediments etc) confirms the tree ring record helps to support the contention that errors in deriving temperature from tree rings are not a significant factor in generating uncertainty otherwise the divergence between tree rings and other proxy measurements would be much greater.

  36. “It appears to me that actual scientists have decided to look into dendroclimatology”.

    I don’t see it that way. Don’t forget that the recent decline in temperatures from dendro reconstructions was hidden by – the now infamous – “Mike’s trick”. The discordance between instrumental records and recent paleo data was a huge stain on the credibility of dendroclimatology. They’re now simply trying to gain back some credibility by claiming that trees are good temp proxies except for the last 20 years, and that therefore there was no LIA or MWP and that there is a hockey stick after all. It’s all about their credibility, funding and keeping the Hockey Stick alive.

    To make matters worse they are now setting themselves up to justify “adjustments” – and we all know what that means.

  37. Perhaps there are some good answers, but a couple things gave me pause:

    Dendrochronologists observed that the older a tree was, the slower it tended to grow, even after controlling for age- and time-driven effects.

    So there’s an age effect, even after controlling for age? What does that mean?

    similar artificial positive signal in the final chronology (as earlier years are only represented by the slow growing trees)

    Presumably, the problem is that the final chronology has an over-representation of fast, not slow growing trees. It is confusing to call these earlier year. Don’t you mean later? Or maybe you mean earlier in the life of the tree. In any event, very confusing.

  38. wayne Job says:
    August 16, 2013 at 2:45 am
    Tree rings are perfectly accurate to tell the age of a tree, or the age that a tree died, every thing else is mysticism, the druids would be proud.
    __________________________________

    Amen!

  39. I am far from an expert on the subject, but it appears that some respondents haven’t even glanced at the literature.

    Of course tree ring growth, in general, is affected by many variables other than just temperature. Water, sun and nutrients to name some of the main ones. This is why dendroclimatologist cannot simply do a study in a nearby forest, they need to identify locations where temperature is viewed to be the main limiting factor.

    This is challenging and imperfect. Reasonable people can differ on how well the goal has been accomplished. However, some of the commenters act as if they are raising these issues for the first time. They are well-known, with attempts to control for them.

  40. Way too early to declare victory here. The “Mann” who gave us “upside down Tijander” is likely to contend that the bias identified in this paper steepens the blade, and thus that modern warming is “worse than we thought”.

  41. These people should do the environment a favour and stop cutting all the flippin’ trees down to look at their rings…

  42. My appreciation for the wonderful senses of humor of WUWT readers has certainly grown in reading this block of comments. “Tree ring circus” is hilarious, but I think “derobustification correction” is my favorite. ;-)
    Greg’s comment about Dendrothermometry or Dendroclimatology being distinct from, but leeching credibility from the long-established study of Dendrochronology makes great sense. There does not appear to be a series of careful, step-wise scientific building blocks that lead to an objective, scientific confidence in Dendrothermometry, and we shouldn’t accept terminology that confuses these two branches of tree-ring studies. We seem to have gone quite quickly from the idea of trees as thermometers to having a full-blown “community” (h/t Lewandowsky) which presumes its own accuracy, relies heavily on Gnostic style mysticism to anwer the many confounding complexities outlined in this thread, and which seems not the least bit interested in testing the foundational questions of this new so-called science.

  43. even if temps and precipitation stayed the same, wouldnt trees have increased growth due to CO2 fertilization alone? it seems like the increase in CO2 since the Industrial Revolution would explain the additional growth, no?

  44. I don’t think you presented the conclusions of the paper accurately in the first paragraphs you quoted. Here’s the relevant conclusion with respect to a modern period positive temperature bias (unrelated to “modern sample bias”)–the paper says there is none–that the proxy bias is actually negative and may account for the “divergence problem” (the infamous “hide the decline” problem):

         “Contrary to prevailing opinion (Brienen et al., 2012a), modern sample bias does not always impart a positive bias on the standardized chronology but depends instead on the complex
    ecological interactions dictating survival and the vagaries of sampling. In fact, in 70.5 %
    of the chronologies analysed, it had a negative effect instead….
    .
         “D’Arrigo et al. (2008) suggest that modern sample bias may be responsible for the “divergence problem” in dendroclimatology, the widespread reduction in temperature sensitivity of tree-ring chronologies in recent decades. The generally negative trend induced by modern sample bias in recent years certainly suggests that this may be at least part of the problem.

    The paper actually supports the idea of a modern warm period as shown in instrumental temperature records–the opposite of what I think your bolded first paragraphs are intended to suggest.

  45. One thing we know about tree rings is that they reflect how much the tree has grown. What we don’t know is if they make an accurate thermometer.

  46. Pete Brown says:
    August 16, 2013 at 6:57 am

    These people should do the environment a favour and stop cutting all the flippin’ trees down to look at their rings…
    >>>>>>>>>>>>>>
    Foresters use a coring tool to count tree rings. <a

  47. Darn the google URL was too large for a working link. Try searching “forester coring tool tree rings image’ instead.

  48. Lets face it, after 70 odd years of pumping CO2 into the atmosphere any changes it has caused are so small as to be imperceptible. Team AGW have been banging the same drum for 30 years now as if climate catastrophe was round the corner. They have all the credibility of a man with a sandwich board calling out “the end is nigh”. Dealing with their “science” piece by piece is lending them some kind of credibility they don’t deserve, suggesting they at least have an arguable position when in fact they have no such thing.

    The climate is not changing.

  49. Greg says:
    August 16, 2013 at 3:04 am

    Very well said. I am very pleased to see that just about everyone writing a comment understands the empirical problems faced by dendrothermometry. Just a couple of years ago many critics of dendrothermometry could not see the underlying empirical problems.

    I am pleased to see that some who practice dendrothermometry, the authors under discussion, are attempting to refine their statistical methods in light of a hard won awareness of systemic bias in tree ring samples. Let the empirical light shine on the statistical magic.

    WUWT has been, and will continue to be, the website where the demands of empirical science are taken most seriously and where sophistication about these matters grows steadily.

  50. The link is to an abstract, rather than the complete document. Since the abstract seems to contradict itself, the complete document should be studied to see if the study is useful in the AGW debate. (I have not read it)

  51. { Alan Mackintosh says:
    August 16, 2013 at 1:15 am }

    Correct.
    Any logger who practices Best Management Practices (i.e. not clear cutting) considers tree age. For example, red oak are most efficient in net dry weight growth until about 30″ Diameter Breast High (DBH). Subsequently, the energy expended to get water and minerals to the top growth foliage requires increasing amounts of respiratory energy for transport, reducing net dry matter accumulation. Therefore when using selective cutting policy, I never felled a tree less than about 30″.
    (Well, if it was a uniform, straight tree with few lower branches probably containing a high percentage of First and Second quality valuable wood I sometimes cut it down to 25″, but don’t tell anyone.)
    Also, as forests age and trees grow, crowns begin to touch each other and the forest canopy closes. Most of the tree crowns will be unable to grow as rapidly as if they had free space to occupy. The photosynthetic capacity will be spread among a greater number of trees. That means less photosynthesis per tree, which translates into slower growth.

    http://plants.usda.gov/java/charProfile?symbol=QURU

    Height at 20 Years, Maximum (feet) 36
    Height, Mature ~80 yrs (feet) 81.0 .
    Do the math.

  52. An Excerpt:
    D’Arrigo et al.(2008) suggest that modern sample bias may be responsible for the “divergence problem” in dendroclimatology, the widespread reduction in temperature sensitivity of tree-ring chronologies in recent decades. The generally negative trend (ref 10) induced by modern sample bias in recent years certainly suggests that this may be at least part of the problem.

    More generally, the theoretical results of this paper clarify, simplify and extend re-gional curve standardization. Regional curve standardization is a biased implementa-tion of signal-free standardization, while signal-free standardization is itself equivalent
    (ref 15) to the new effect regression standardization. Working within a regression framework improves the transparency of the standardization process, allows investigators to use classical regression tools such as AIC and, as demonstrated, facilitates investigation
    of alternate underlying models of tree growth.

    I certainly support “may be” and “suggests”. The paper is important, and should stimulate other papers on the problem, including “regional curve standardization.” I can imagine a cottage industry growing from this.

  53. @- jim2
    “One thing we know about tree rings is that they reflect how much the tree has grown. What we don’t know is if they make an accurate thermometer.”

    However lumber companies use the temperature history of a stand of trees to estimate the amount of wood they can extract. There are other factors of course, but at least to a first approximation just the temperature record is a good correlate with tree growth.

    REPLY:They also consider rainfall. Bulk production correlation of temperature to thousands of trees is easy, reverse correlation getting temperature from a few trees (like YAD06) not so much, which is the central issue to bollixed paleoclimatology- Anthony

  54. The link is to an abstract, rather than the complete document

    follow the hint: the full paper is here etc.

  55. This is amazing. In a previous epoch (how’s that for a start?) I wrote a comment on this site concerning the similarities between Michael Mann’s research and my sister’s, my older sister’s fungal toe.

    Well, what a coincidence. It was just this very week, this very week, that my sister, my older sister (ok, I’m getting repetitious), went again for treatment for her fungal toe, her first follow-up treatment since my previous comment. And, lo and behold, what occurs almost simultaneously to that treatment is another story on this site about Michael Mann. I mean it’s weird but it’s almost as if the fungus in her toe has a relationship with Michael Mann. And, what the heck, why not? Why shouldn’t two distinct living organisms which exist (or are funded) solely through the blood and sweat of host organisms, which never go away but instead keep coming back and back again, why shouldn’t they have a relationship. (Izen, are you listening?)

    While there’s not much difference between a fungal toe and Michael Mann’s research there is a big difference between Michael Mann’s research and my older sister. You see, when my older sister wants to intimidate me she waves her contagious fungal toe at me, but I don’t think the IPCC waves Michael Mann’s tree ring research at anybody anymore.

    BTW: Welcome back Richard Courtney.

  56. I made a comment a few years back at Climate Audit that if one were going to use tree rings for temperature proxies, it needed to so in a manner in which any year’s measurement had to come from trees that were of the same age. So, if one were going to measure a temperature in 1560, for example, then one would measure it a tree that was X years old in 1560, and measure temperature for 1980 in a tree that was X years old in 1980.

  57. We’ve had many thousands of thermometers around the planet measuring temperature and still can’t agree entirely on what its been doing the last 15 years or even 100+ years based on how you interpret the data or the location of the instrument shelter/weather station(with respect to urbanization).

    And trees, being greatly effected by more elements than temperature(precip is often more important) from hundreds of years ago can do this?

    The uncertainty over what caused the size of each ring long ago is too great to be making assumptions. Guesses yes.

    Regarding recent data. How much error is being introduced by not properly dialing in the huge growth of woody stemmed plants/trees in response to increases in CO2?

    If you’re a scientist that believes CO2 is bad, it’s highly unlikely that you will acknowledge and fully/accurately account for massive new growth based on just the CO2 fertilization factor.
    Doing so would be evidence of the most powerful benefit of CO2 that overwhelms any effect on temperature.

  58. I proposed this theory many years ago (http://www.nrcresearchpress.com/doi/abs/10.1139/x88-032) in1988 and showed that data support it. The basic idea is that slower growing species (or trees within species) will live longer because the reason they grew slower was better investment in defenses such as thick bark and defensive chemicals. The oldest trees thus have a bigger percentage of the slower growing trees and the young trees are a more random sample, with more fast growing individuals. This creates the bias and the hockey stick.

  59. Most of these studies seem to be of old trees in temperate and colder climates. Alan above notes ” … Birch … maturity … 70-80 years ….Oak, … several hundred … 40 – 50 years …. Spruce …” Conspicuous by their absence are any studies of trees in tropical climates.
    Here at 19° 11′ 38″ S 146° 40′ 31″ E I have two tree stumps from a local Acacia species. One planted 23 years ago as a “whip” eg 1m+ high. In 2011 it was about 15m high, 12m diameter crown, diameter of trunk at base maybe 700mm. Benefited from profligate irrigation next door. Another, planted from tube-stock about 15 years ago, might be a better candidate for analysis as this had no artificial irrigation or nutrients. In 2011 height was at least 20m, trunk diameter maybe 500mm. Along with other mature trees, these were severely damaged by Cyclone Yasi, I ended up with about 15 tonnes of felled timber from a mere 1347m2. More tree-ring specimens than would fit in Mann’s office. Significant increase in tree ring width after about 2004, and nothing to do with increase in temperature, precipitation or insolation, because according to local BoM monitoring (20km ESE on the same coastal plain) there wasn’t any.

  60. Looks like slowing growth in old trees scotches the left wing fetish for old growth forests as a carbon sink. And why no interest in increasing the organic material in soil? Far better to leave the plant material in the soil.

    -T

    “Basically, older trees grow slower, and that mimics the temperature signal paleo researchers like Mann look for.”

  61. ‘ralfellis says:
    August 16, 2013 at 1:14 am
    >>Unless you correct for this issue, you end up with a
    >>false temperature signal.

    But will you end up with a temperature signal at all? Here are a few scenarios for you…

    a. Tree experiences a very cold summer, with no growth. (a temperature signal?)
    b. Tree experiences a very hot but too dry summer, with no growth. (a temperature signal?)
    c. Tree experiences a cool but nicely moist summer, with good growth. (a temperature signal?)
    d. Tree experiences a very hot and wet summer with good growing conditions but a rampant pest infestation, with no growth. (a temperature signal?)

    ###################

    before folks reject tree rings out of hand, or merely by waving their hands its important to get the argument correct. In other words it’s best to describe your opponents argument fairly and then go to work on the weakest parts.

    The growth of trees is limited by several factors. When selecting a tree as a treemometer the scientist will try to

    A) select a species that is particularly temperature sensitive.
    B) select a stand of trees where the growth is temperature limited

    Even wikipedia knows this.

    “Climate factors that affect trees include temperature, precipitation, sunlight, and wind. To differentiate among these factors, scientists collect information from “limiting stands”. An example of a limiting stand is the upper elevation treeline: here, trees are expected to be more affected by temperature variation (which is “limited”) than precipitation variation (which is in excess). Conversely, lower elevation treelines are expected to be more affected by precipitation changes than temperature variation. This is not a perfect work-around as multiple factors still impact trees even at the “limiting stand”, but it helps. In theory, collection of samples from nearby limiting stands of different types (e.g. upper and lower treelines on the same mountain) should allow mathematical solution for multiple climate factors. However, this method is rarely used.”

    http://en.wikipedia.org/wiki/Dendroclimatology

    a good blog comment starts with a little research.

    Then its important to realize that you can actually test whether a temperature signal exists.

    1. Take cores from tree rings going back to 1850
    2. Use the instrument record from 1900 to present to calibrate
    3. Predict the temperature from 1850 to 1900 using the calibration ( called verification)
    4. compare your prediction against the actual.

    So, when you see St. McIntyre slamming Mann because of verification statistics you see the Stronger argument against the result. The weaker argument just dismisses all tree rings.
    The weaker argument says “we cant know”. the weaker argument is anti science.

    The stronger argument accepts that we might be able to tease out a temperature signal and then systematically challenges all the assumptions and methods used to extract that signal.
    the stronger argument does not presuppose that we cannot know. The stronger argument is a specific argument against a specific case and not a general dismissal based on a specific cases.

    Just what are they measuring, when looking at tree rings? Temperature? Moisture? Infestations? Micro-climates? Forest canopy competition?

  62. Steven Mosher says:
    August 16, 2013 at 9:12 am
    ————————————————–
    1. Take cores from tree rings going back to 1850
    2. Use the instrument record from 1900 to present to calibrate

    Regarding (1), how do you obtain a global sample?
    Regarding (2), doesn’t the proxy record diverge from the 1960-present? If so you’re already in trouble without going back much more than 50 years. If we can’t go back 50 years how can we go back 150 years?

    It would make more sense to compare different proxies and not let any one proxy (e.g. tree-rings) dominate the so-called science. Where is the hockey-stick in other proxies?

  63. Having cut down many trees of known age from my youth I’ve always been suspect of tree ring data. Water has just as much influence on a tree ring as does sunlight, perhaps even more.

  64. 2. Use the instrument record from 1900 to present to calibrate
    ====
    Then it will never be right, will it Mosh?

  65. Steve from Rockwood says:
    ————————————————–
    1. Take cores from tree rings going back to 1850
    2. Use the instrument record from 1900 to present to calibrate

    Regarding (1), how do you obtain a global sample?-
    You don’t- you’re measuring local temperature changes- Alan McIntire

    Regarding (2), doesn’t the proxy record diverge from the 1960-present?
    That won’t be a problem because by definition the new proxy will match temperatures 1900 to present- Alan McIntire

    It would make more sense to compare different proxies and not let any one proxy (e.g. tree-rings) dominate the so-called science. Where is the hockey-stick in other proxies?

  66. Steven Mosher says:
    August 16, 2013 at 9:12 am

    “The growth of trees is limited by several factors. When selecting a tree as a treemometer the scientist will try to

    A) select a species that is particularly temperature sensitive.
    B) select a stand of trees where the growth is temperature limited”

    I sincerely hope that you do not think that your comment does justice to the empirical questions that underlie the use of tree rings as temperature proxies. When used as a temperature proxy, a tree must be calibrated in just the same way that a thermometer is calibrated. Because trees are not manufactured you must do experiments on the individual trees to determine how they respond to changes in local environment. Does this mean that tree rings are unsuitable as proxies for temperature? Most historical records are useless because neither the tree nor its environment are available for experimentation. Some short historical records might be useful. However, because the “scientists” who use tree rings as proxies cannot bring themselves even to consider that experimentation is necessary, the question is moot.

  67. When used as a temperature proxy, a tree must be calibrated in just the same way that a thermometer is calibrated.

    Trees are calibrated against other proxy data that is also wrong else they wouldn’t agree. This isn’t rocket science.

  68. @Greg at 3:04 am:
    “There is a wilful attempt by many involved in dendroclimatology and particular dendrothermometry to confound all these terms in the hope that unscientific attempts to use trees as thermometers will get a free pass and be granted the hard-earned credibility of dendrochronology.”

    Greg, add in that botanists use the same tree rings to determine precipitation. The botanists assume constant temps year-to-year, and the dendroclimatologists assume constant precipitation. Obviously, both can’t be right. The answer is that both are major factors in tree-ring growth, and that no one can look through a crystal ball into the past and tell which of the two factors contributed how much to any single tree ring.

    This overall puts the entire “science” of dendroclimatology on very thin ice.

  69. If you sit down and actually calculate the volume of new wood laid down per year, the surprise is that Old Trees do not grow more “slowly.” In fact they tend to add wood at increasing rates as long as they remain healthy. The reduction in ring thickness is because new wood is added to entire outer surface of the tree (trunk, branches and all) and that surface steadily increases with time. The ring pattern only appears to reflect slower growth over time.

    Also, dendrochronology is perfectly serviceable as a dating tool regionally. It continues to work well for instance in the American southwest for dating construction work in Anasazi and other contemporary sites. What we don’t know and probably never will, are the precise environmental elements that create those regional patterns. Water availability almost certainly, but other things as well. Mann and his team don’t do dendrochronology but something more akin to “dendrophrenology.” They look at the bumps and slumps in growth and claim to interpret them. Lay off on dc and start picking on it’s misuse instead.

  70. Addressing the overall issues in climate science, as time has gone on and we have learned about the details that are important for each and every kind of temperature reconstruction, we keep finding out that certain assumptions that we on the sidelines thought were “settled science” simply are not valid at all. There is and has always been a wrongness to the assumption that tree ring growth over the life of a tree is constant. That is the point of this paper.

    People looking at reconstruction curves initially assume the details have all been dealt with. Yet every half year or so we find out differently. The details have NOT been considered properly.

    This paper even castigates the reconstructionists for not having properly included this extra “term” (factor) in their formulas – the ones that go into producing the curves we see. If I understand them correctly, the authors point out that without this factor figured in the older growth will be seen as slower – and therefore COOLER. This, they seem to say, tilts the curve and long-term trend lines upward, giving the ARTIFICIAL appearance that recent times are hotter.

    This is a BIG deal. Reconstructionists are not filed climatologists; they take others’ work and assume all the details have been worked out so that the field workers’ output is standardized to the final degree. All the reconstructionists do is sit at their computers and take the results and plug in the data as if it is 100% reliable. This paper argues that such is not the case.

    Excellent!

  71. The Divergence Problem.

    This paper needs to be taken into context with the Divergence Problem. The recent tree-ring data ALREADY shows far too low of a trend since 1940. If added together, the two mean the tree-ring vs measured temps is even MORE diverging.

    This is a BIG deal.

  72. @Duster at 10:38 am

    Yep. People need to stop confusing dendrochronology with dendroclimatology.

    The former is, more or less, counting rings, regardless of width, in order to date artifacts and sites.

    In order to “back-predict” temperatures, the latter makes the assumption that precipitation is constant, and that assumption is unsupportable, even if the scientific community hasn’t recognized the disconnect yet.

  73. dp says:
    August 16, 2013 at 10:32 am
    “When used as a temperature proxy, a tree must be calibrated in just the same way that a thermometer is calibrated.

    Trees are calibrated against other proxy data that is also wrong else they wouldn’t agree. This isn’t rocket science.”

    You are correct, sir. I should have extended my comment to say that a tree’s environment is dynamic and that experimentation must be continued over the entire period that the tree is used as a proxy. Other problems remain. The most notable is comparing local environments from different regions.

    A forest is dynamic. It is rarely like a stand of thousand year old Sequoias. It is no less dynamic than a beach on a barrier island on the east coast of the US, to borrow one of Willis’ examples.

  74. While the final analysis above seems to hammer another nail in the CAGW dendro addiction illness, the paper seems to avoid or blindly assume what trees do because they look at the rings. Talk about not seeing the forest for the trees, now it’s they can’t see the tree for the rings.
     
    As Gary Pearse mentions above, there is much in forestry that dendro-chronologists could learn from. Add to that what woodworkers and luthiers have learned over the centuries and perhaps much of this voodoo chronology thinking could be moderated.
     
    When I look at tree rings, all too frequently as I actively cut wood for wood stove heat in the winter, I find myself wondering just what the rings can actually indicate. One signal that is quite clear here in central Virginia is the drought cycle that is likely influenced by ENSO.
     
    Counting the years get very iffy, especially in the older trees. If one follows some of the odd rings around the tree, they seem to merge, diverge, wither away. Very puzzling, was the tree damaged on one side that year? I’ve not taken any of these curious ring cuts inside to put under the binocular microscope, to verify whether or not the rings really do merge, diverge, whatever. Just not interested in the chrono part that much. Wood inside. good, into the stove, aahhh.
     
    In all of the wood working fields and perhaps especially in luthier work, it is well known that trees grow in response to local conditions. An ideal tonewood tree is evenly grown, flexed evenly by the winds and straight as a telephone pole.
     
    Yes, a tree does grow thinner rings as the tree gets older. It’s not that the tree is tired and old. What happens is that the tree fills the ecological niche and attains it’s range of maximum leaf and root mass in it’s little competitive spot. This plateau of leaf mass and root systems are significant drivers towards thin even rings. Food, water, sunlight, fire are all major inputs that cause changes to tree mass. Did something drop a large pile of fertilizer on one tree’s root ball, then the root mass will develop complexity, leaf mass will increase and the tree will attain a brief growth spurt, perhaps indicated by micrometers in ring thickness. No fertilizer, less water, bug infestation, fire destroys leaf mass and injures the cambium layer and the tree makes a thin tree ring. As far as I know, the rings do not indicate the provider of abundance nor do they indicate meager sustenance, lack of water or physical damage, (remember, cambium is often damaged, not destroyed or seriously marred).
     
    Luthiers love tonewood trees with thin rings. The deal is that trees have thick rings during their early life and as the tree gets older and more massive, the outer tree rings get thinner. Only the rings closest to the cambium layer are not as stiff or stable as heartwood.
     
    Now stating as the tree gets older tree rings get thinner is an automatic blind spot in thinking about the tree. As a tree reaches it’s maximum available resource intake concurrently it achieves it’s maximum growth capability in building tree rings on an ever expanding column of wood. The newest ring may still have greater total volume than the previous year’s ring.
     
    As I explained above, I’ve never put this wood under a microscope, measured mass on a Mettler scale (it’s what I have), measured thickness and density over decadal ring growth periods and charted this out. Still, I suspect that the tree manages to slightly increase the total wood mass through a larger cambium area every year, but the rings are thinner as the tree builds over larger wood acreage every year.
     
    Again, back to the wood; there are issues that can occur in every tree. The overall term is ‘reaction wood’ as the tree’s cellulose product is in response to environment conditions. A common adverse growth condition in conifers is compression wood.
    Compression wood forms when the tree is under stress from leaning, snow loads, excessive growth on one side, hard steady winds over long periods. What happens is that the growth of the tree is affected with eccentric growth rings. (adapted from “Understanding Wood, A Craftsman’s guide to wood technology”, R. Bruce Hoadley)
     
    These are local effects from a range of conditions and like many other effects, they can be changed when conditions change. A leaning tree because the hillside slumped, straightens when the hill slumps again. Branches break off and snow loads or wind burdens shift. Every change changes the tree ring growth, often in ring thickness.
     
    Local on the tree conditions affect tree rings within those conditions. Insects, twig or branch growth, deer rutting, carnivores sharpening claws and so on change tree ring widths. What is worse, Many of these conditions are extremely difficult to spot unless one happens upon the exact source or cause.
     
    Luthiers and wood workers know that wood cut parallel to the tree’s height is strongest, especially when all of the wood grain is parallel. The best way to achieve this is to split the wood along the wood fibers. A luthier carving violin or cello tops from spruce or maple will pay a significant premium for well-cut tight grained wood. These same luthiers all too frequently spend hours carving the wood only to discover a pin-knot, bug-hole, hidden reaction wood or other flaw. As a side note, cello luthiers carve tops from wood that starts out 18 to 25mm in thickness down to 1-2mm thickness for a well sounding top.
     
    Back to the dendrochronology folks out boring a tree’s poor sacroiliac with their tiny bits and corers believing that such small looks within a tree’s life will tell them everything about that life. If people whose livelihoods depend on wood cannot tell before carving an entire piece of wood just what is in every particle of that wood; I seriously doubt that small cores can do much more than hint with huge chances for error. Just because a researcher can measure the width of a tree ring in a core, doesn’t mean that that ring is consistently that width even within a few millimeters.
     
    All trees are sensitive to temperature; but they’re far more sensitive to sunlight, water and nutrients. A small change in sunlight falling upon the tree causes major changes in tree biosphere. Consider the hard maple ‘Acer saccharum’ where sap is collected in late winter. The trigger is “…The flow of sap is triggered by a thaw following on a hard frost in the sunny days of late winter (February, March and April)…” Note that caveat of ‘sunny days’, the sap flows best on bright sunny days regardless of the temperatures. Please do not mistake ‘thaw’ for winter is over and birds are singing spring; it is literally the first warmish days concurrent with bright sun and can occur January through March. Collecting sap by hand means trudging through snow to the trees and trucks. Buckets left overnight can be ice capped, (still goes into the collecting tank). The sap season can also be spotty and not give a good run if the weather and sun don’t allow it. Spring still arrives, leaves flesh out and summer arrives. It isn’t just the warmth! We may think trees are stone cold, but the trees are still engaged in life.

  75. Reblogged this on Public Secrets and commented:
    This is potentially a huge blow to the Cult of Anthropocentric Global Warming. Tree-rings have been used as proxies, in lieu of having direct instrumental measurements of temperature change in ages past. They’ve been foundational to the assertion of a connection between CO2 levels and warming, and thus as evidence that Man has accelerated that warming. And if it turns out the tree-ring analysis was severely biased…. Well, Al Gore won’t be pleased at all.

  76. ATheoK says:
    August 16, 2013 at 11:40 am

    Excellent little essay, ATheoK. Light is a huge variable in tree growth. Trees compete with one another for available light and put themselves through all sorts of compression to get to the light. The amount of available light for each tree changes dynamically as the competition proceeds. Also, most forests are on rather hilly ground. The effect of the hills, river gulches and such is to make the available light highly variable on the ground. Saplings ten feet apart can receive vastly different amounts of light. Pity the poor Luthier.

  77. “Theo Goodwin says: August 16, 2013 at 11:11 am


    You are correct, sir. I should have extended my comment to say that a tree’s environment is dynamic and that experimentation must be continued over the entire period that the tree is used as a proxy. Other problems remain. The most notable is comparing local environments from different regions.
     
    A forest is dynamic. It is rarely like a stand of thousand year old Sequoias. It is no less dynamic than a beach on a barrier island on the east coast of the US, to borrow one of Willis’ examples.

     
    That still only gives a tiny window of a few years against the entire lifetime of the tree. All that one could be sure of is the conditions prevalent during the proxy study period; and that only if someone is there full time to record local variables.
     
    The sequoia comment is interesting. I greatly enjoyed my stay at Sequoia National Park and hiked through several groves. I was astounded to see trees with deformities from local impacts; one tree lost a large piece of it’s top and most of it’s leaf mass (needles). Yup, they’ll sure know in another thousand years that the tree lost it’s top and tree rings are thin because of the loss in photosynthesis. Three other trees were burned, mostly on one side from a fire years before. A number of other trees were not, but they’re side by side; the difference is brush fires burn fast without much tree damage while accumulated fallen deadwood burns hot. A truly tall tree that was only five – six feet (almost two meters) thick fell and opened up a long sunlit glade…

    Even amongst the sequoias, bristlecone pines and redwoods the forests are dynamic.

  78. Steven Mosher says:
    August 16, 2013 at 9:12 am …..
    1. Take cores from tree rings going back to 1850
    2. Use the instrument record from 1900 to present to calibrate
    3. Predict the temperature from 1850 to 1900 using the calibration ( called verification)
    4. compare your prediction against the actual.

    So, when you see St. McIntyre slamming Mann because of verification statistics you see the Stronger argument against the result. The weaker argument just dismisses all tree rings.
    The weaker argument says “we cant know”. the weaker argument is anti science.
    ============================================================
    Absolutely incorrect.
    First of all, which iteration of the instrument record would you recommend for calibration? For instance, not to pick on GISS, but, because it’s handy …. http://suyts.wordpress.com/2013/08/14/gisss-first-30-years-of-our-temp-record/

    So, which one would you use for calibration? If you used the older iteration of our temps, and they give us another version which alter the historic temps, as we continually do at all levels (GISS only bringing us a final product), then we know that the calibration would necessarily be in error because the temps used to calibrate are now different. So, in that sense, it is entirely based upon strong science and argument that it can’t possibly be done.

    Every tree ring study, or any and all paleo studies using past instrument records to calibrate are in error today because the past instrument records have changed. You can use GHCN, NOAA, GISS, HadCrut …. any and all and you absolutely do know that the calibration period has been altered since the time of the study. They are not correct and cannot be correct because of the continuous history revisionism.

    But, more to the point, we also absolutely do know that dendro studies are nothing but numerology. Photosynthesis, necessary for tree growth is done through the leaf or pine needles. We know that various preceding years will directly effect the growth of the subsequent years. Meaning that each year retains a signal from the prior years irrespective of what occurred in the year being addressed. Bristle pine, for instance, can retain their needles for up to 60 years. And, probably longer. But, we don’t know, and can’t know how much each year contributes to the year being addressed as it would be different for each and every tree.

    I love the contributions Steve Mc has made to climate science and our knowledge. But, in these instances, the elegant statistics used, clouds and confuses the discussion. And, it lends a form of legitimacy to the lunatics making proclamations about our temps using tree rings, because it allows for the possibility that one can, and puts forth an argument that it was just their maths that was wrong. It isn’t their maths!! It is their lack of understand base and fundamental science! And this paper once again establishes that the lunatics don’t have a clue as to what they’re doing.

    It isn’t a strong argument to prove the moon isn’t made of cheese with statistics. It’s a waste of time and muddles the discussion.

    Again, for clarity, I am not dismissing Steve Mc’s contribution. He can rightfully take credit as being one of the driving forces in the skeptical movement. He demonstrated alarmist fallibility and by my reckoning, humanity owes him a debt. But, we’ve moved on from that point and now we’re at the point of establishing that alarmists have zero credibility because their assumptions are not based on science.

    Who knew that trees are physically limited in their growth capacity and that as they age they grow slower? Well, just about any 4th grader out there….. well except for the poor children being taught today. God knows what they’re teaching them now.

    I love numbers. Numbers are great! But, they carry no meaning if they are not properly derived. It is numerology. Elegant and sophisticated, but numerology nonetheless.

  79. James Sexton:

    With respect to global temperature data against which treemometers are calibrated, at August 16, 2013 at 12:42 pm

    http://wattsupwiththat.com/2013/08/16/oh-mann-paper-demonstrates-that-tree-ring-proxy-temperature-data-is-seriously-compromised/#comment-1392486

    you say

    I love numbers. Numbers are great! But, they carry no meaning if they are not properly derived. It is numerology. Elegant and sophisticated, but numerology nonetheless.

    Yup! I have been trying to explain that to anybody who would listen for years;
    e.g. see http://www.publications.parliament.uk/pa/cm200910/cmselect/cmsctech/memo/climatedata/uc0102.htm

    Richard

  80. { @izen says:
    August 16, 2013 at 8:21 am
    However lumber companies use the temperature history of a stand of trees to estimate the amount of wood they can extract. There are other factors of course, but at least to a first approximation just the temperature record is a good correlate with tree growth. }

    I call B.S. they use precipitation data.
    I googled it. You can try.

  81. richardscourtney and James Sexton:
    I will add my name to those two and state that there are to many problems with Dedrochronology to be able to derive any useful temperature records. There are to many problems with the surface temperature records to accurately claim what changes have been experienced even during the time thermometers have been in use.

  82. “Theo Goodwin says: August 16, 2013 at 11:59 am

    The amount of available light for each tree changes dynamically as the competition proceeds.
     
    Also, most forests are on rather hilly ground. The effect of the hills, river gulches and such is to make the available light highly variable on the ground. Saplings ten feet apart can receive vastly different amounts of light.
     
    Pity the poor Luthier…”

     

    My apologies for the windy epistle. It is also interesting to understand how forest trees adapt and grow within a forest to achieve a mature forest. While that sounds great, it isn’t the best for wildlife in general. Deer and other ungulates are primarily grazers and broken country serves them best. From open glades through meadows, young forests and old growths, all support different creatures differently.
     
    Theo: I don’t recall where you are physically located, but here in America we have forests on flat, hilly and mountainous land. The forests in Alabama, Louisiana, Florida and parts of Mississippi are on quite level ground, old sea floor.
     
    There is a hike on a local Boy Scout campground; it is about five to seven miles from hilltop to hilltop and over the course of a week the patrol visits as many hilltops in six days as they can. The name of the hike is something like “Seven Scenic Peaks”.
    Well Virginia does have some peaks, but most of these hike hilltops were hills, just tall ones. When the hike was originally set up many years ago, the area had been logged and when one reached a hilltop there was a good view. Nowadays, one gets to see trees, tall mature trees, in all directions and I’m not going to try and climb one, seven or more hiking miles from doctoring.
     
    Ever hear of a rich luthier?
    Even the incredible ‘Antonio Stradivari’ (Stradivarius) is reputed to have searched firewood piles for possible tonewoods. Antonio personally selected his tonewoods and then air dries those woods for years.
    A comparison of tree ring widths of Stradivari instruments shows that many of his instruments, including the most famous, have wider tree ring widths than currently favored by luthiers; master grade tone wood today often boast ring widths of 30-40 rings per inch while one study has the violin masters making instruments with woods from 5-25 rings per inch.
     
    While the study results versus ‘consensus’ are opposite to some degree there are a number of luthiers who are seriously testing their tonewood densities and constructing their instruments accordingly.
     
    Tapping instrument wood listening to the tone tap is a very old method for judging how good a tone wood is. Perhaps what the masters tapped for was stiffness along with tone.

    Thank you for your kind praise,
    Another Theo.

  83. “But, we’ve moved on from that point and now we’re at the point of establishing that alarmists have zero credibility because their assumptions are not based on science. “

    Well Said!

  84. You put a tree ring in,
    You take a lake core out,
    You put your garbage in,
    And you shake it all about,
    You make the Hockey Stickey
    and your cash cow comes around
    That’s what it’s all about.

  85. Steve from Rockwood says:
    August 16, 2013 at 9:42 am

    Steven Mosher says:
    August 16, 2013 at 9:12 am
    ————————————————–
    1. Take cores from tree rings going back to 1850
    2. Use the instrument record from 1900 to present to calibrate

    Regarding (1), how do you obtain a global sample?
    Regarding (2), doesn’t the proxy record diverge from the 1960-present? If so you’re already in trouble without going back much more than 50 years. If we can’t go back 50 years how can we go back 150 years?

    ===================================================================
    I’ve commented before how the temperature record for my little spot on the globe has been changed (“adjusted” if you prefer) between 2007 and 2012.
    Which instrument record would you use for #2? The “raw” data or the “corrected” data?

  86. richardscourtney says:
    August 16, 2013 at 1:14 pm

    James Sexton:

    I love numbers. Numbers are great! But, they carry no meaning if they are not properly derived. It is numerology. Elegant and sophisticated, but numerology nonetheless.

    Yup! I have been trying to explain that to anybody who would listen for years;
    e.g. see http://www.publications.parliament.uk/pa/cm200910/cmselect/cmsctech/memo/climatedata/uc0102.htm

    Richard
    ================================================
    I know Richard, and you’ve done a great job at articulating this thought. What I don’t get is why it is so hard for other people to recognize this? The temp records are a huge circle of self-affirmation. As you’ve pointed out, they don’t really agree. But, in some views they can generally agree, but, that’s only after revisions.

    They revise to maintain the general agreement, and claim validity because the various data sets generally agree. How stupid is that? But, we can’t get even many of the skeptics to acknowledge this basic fact and flaw in the climate thinking.

    All of the models, all of the sensitivity calculations, all of the studies regarding historical temps are in error. They calibrate against air and imagination!

  87. When I first got interested in AGW about ten years ago, the first thing I did was get out my old college botany book. After my study, I rejected the dendro story for the reason outlined here, as well as others.

    I have to wonder if any of the dendro folks have even a nodding acquaintance with biology.

  88. I’m with Mosher on this one. With respect, some of the comments in this thread seem more scoffing (underinformed) than skeptical.

    I have a friend with an advanced degree from MIT who is a CAGW believer. When I asked him why, he replied that a local professor showed simple back-of-napkin math in a public lecture that proved to him that the earth must warm drastically as CO2 levels rise. Sadly, having been so easily persuaded, he never dug any deeper.

    In whatever direction, drawing and expressing oversimplified, underinformed conclusions only entrenches ignorance..

  89. ATheoK says:
    August 16, 2013 at 2:21 pm

    I grew up in the largest National Forest (a managed forest) outside of the Pacific Northwest. It is in northwest Alabama. My father owned a sawmill and employed logging crews. I walked tracts of timber to see if they were suitable for purchase when I was twelve years old. This was before clear cutting had been imagined. We examined thousands of trees one at a time. North Alabama, north of Birmingham, is total hills. Walking through the forests is an up and down experience. South Alabama, south of Montgomery, is where the plantations were and it is flat.

    Any praise that I gave your post is well deserved. Also, I am always happy to encounter someone who knows forests and what some creative people can do with forests and trees. Thanks for your stories, especially about the Luthier.

  90. Mosher sed:

    The weaker argument just dismisses all tree rings.

    I believe it is more accurate to say the tree ring investigator is being dismissed, not the tree. The tree cannot help but be what it is but the investigator as often as not makes the tree what it is not. That being a stepping pad to fulfilling the CAGW agenda. Never misunderestimate the skeptic mind – we’ve learned what the climate hysteria advocates have not – It is harder for the CHA team to be more honest than accurate. That is to say, their numbers don’t add up. Briffa seems to be the only squeamish one of the bunch as revealed in the CG letters and post-CG statements.They have all lost credibility by being incredible as a group.

  91. Borderline off-topic:

    The discussion of growth variation reminds me of how tree rings work (or semi-work) for temperature reconstruction at all only because vegetation like trees typically grows significantly faster during warmer times (although also affected by carbon fertilization and non-temperature factors). Nominally such is just stating the obvious. However, CAGW-movement publications are able to report on a tree ring temperature reconstruction like the skewed hockey stick of Mann, then spin around to practically implying global warming has had no benefit or harmed the biosphere, with only a few noticing the internal contradiction (because many people don’t keep enough disparate pieces of info in the front of their mind simultaneously).

  92. Here is a tree-ring paper which is a joy to read. It was published in Ecology vol.1 no.1 Jan 1920.
    Evidence of Climatic Effects in the Annual Rings of Trees by A.E. Douglas.

    http://ltrr.arizona.edu/sites/ltrr.arizona.edu/files/bibliodocs/Douglass%2C%20AE_Evidence%20of%20Climatic%20Effects%20in%20the%20Annual%20Rings%20of%20Trees_1920.pdf

    The paper is also available here, but the above link is nicer and it is signed by the author.

    http://www.jstor.org/stable/view/1929253

    From Wikipedia: “Douglass founded the discipline of dendrochronology, which is a method of dating wood by analyzing the growth ring pattern. He started his discoveries in this field in 1894 when he was working at the Lowell Observatory. During this time he was an assistant to Percival Lowell and William Henry Pickering, but fell out with them, when his experiments made him doubt the existence of artificial “canals” on Mars and visible cusps on Venus.” Another skeptic doubts the dogma story.

    He was looking for the solar cycle in the tree rings. He found it, but it was only a small effect.
    For more history about Douglas and background for the above paper, see

    http://www.treeringsociety.org/TRBTRR/TRRvol59_1_21-27.pdf

  93. Ralfellis says: August 16, 2013 at 1:14 am
    a. Tree experiences a very cold summer, with no growth. (a temperature signal?)
    b. Tree experiences a very hot but too dry summer, with no growth. (a temperature signal?)
    c. Tree experiences a cool but nicely moist summer, with good growth. (a temperature signal?)
    d. Tree experiences a very hot and wet summer with good growing conditions but a rampant pest infestation, with no growth. (a temperature signal?)
    _________________________________________

    Steven Mosher says: August 16, 2013 at 9:12 am
    When selecting a tree as a treemometer the scientist will try to
    A) select a species that is particularly temperature sensitive.
    B) select a stand of trees where the growth is temperature limited
    _________________________________________

    Well, they did not do very well at Yamal, then, did they? No two tree rings series from Yamal looked the same – some were up, some were down. What you are saying is that despite the careful selection process, you STILL cannot find a good reference tree-ring series. So at the end of the day, you toss a coin to decide which trees to accept. (“Let’s hear it for YAD 061 – the loudest cheer wins….”)

    And your explanation also completely demolishes the pseudo-science of dendrochronology – because your test wood sample for dating was most certainly not selected by your criteria. In fact, you will most probably have no idea where the sample came from. So how can you compare it to the ‘select’ reference trees?

    And so we must turn again to the defenders of dendrochronology, like Greg, who are desperately separating it from dendrothermometry. Just what do you think the dendrochronologists are measuring?? Do you think there is a date embedded into each tree ring?

    No, they are measuring the width of tree-rings, and the changes in the width of successive rings to build up a graphic of good and poor growth. And what causes those tree-ring changes, eh? Ah, yes, temperature and moisture – as well as nutrients, pests, tree age, and canopy cover. So please do tell me, how the test sample of wood (which came from a balmy glade in southern France) can compare with the reference sample that came from a select micro-climate in California or the wetlands of Southern Ireland? Just what is the link between the two? None. And so how can you compare them?

    Oh, and I forgot to say that the test sample had a five-year pest infestation, which resulted in 5 years of no growth in the middle of the sample (which looks like 5 years of cold or dry weather). Now how do you match the test and reference samples? Ah, yes, I know – you find 5 successive years of no growth in the reference sample, which equates to 687 BC. But then the archaeologist complains that the boat was built in the 17th century…..

    Voodoo science.

    .

  94. “A likelihood perspective on tree-ring standardization: eliminating modern sample bias”

    This is a very interesting paper. The conclusion is that it is possible for a biased climate ‘researcher’ to cherry pick data dendro chronological data to push one’s own climate change agenda.

    Mann cherry picked inaccurate dendro chronological data, hide that cherry picked data from other researchers, hide the faulty application of a mathematical algorithm that was used to enable the cherry picked inaccurate data dendro chronological data to create the ‘hockey’ stick. An indicate that Mann’s paper is incorrect scientifically and appears to be the work of an advocate is the hockey stick is not supported by other proxy data, is not supported by previous analysis by prominent scientists, not supported by the historical record written by people at time (which note climate facts such as the Medieval warm period was a warm period or the Little Ice Age was a cold period) and is not supported by agriculture practices at the time (such as which Northern regions could or could not grow grapes for wine production and famines due to crop failures during the cold times, such as the Little Ice Age.).

    To eliminate sampling bias from ‘modern’ climate research, there needs to be a test to determine if the research is done by a scientist rather than an advocate who is trying to create propaganda. There needs to be another paper written on the problem of climate advocates posing as climate scientists. There needs to be a paper written on the climate advocates blocking so called ‘skeptical’ papers in climate research publications. There needs to be a paper written that explains how and why Mann’s hockey stick graph was used by the IPCC to push an agenda.

    http://wattsupwiththat.com/2013/08/16/historic-variations-in-temperature-number-four-the-hockey-stick/

    Greenland ice temperature, last 11,000 years determined from ice core analysis, Richard Alley’s paper.

  95. Isn’t the fact that the paper is published a reason for celebration? It shows that the stranglehold the AGW crowd had on the peer review system is weakening.

  96. ralfellis says:
    August 17, 2013 at 3:34 am

    What a bracing argument. Woke me from my dogmatic slumber. Maybe dendrochronology is not sound after all.

  97. Two comments regarding reading the tree rings
    1) All plants have an optimum temp growing range, too cold = slow growth – too warm = slow growth. How do you differentiate between small tree rings due to being too cold and being to hot
    2) global temps (ave) vary only slightly from year to year (.02 c or less). However, local temps can very immensely from year to year. For example, the temp difference in north texas during 2011 was approx 2.0c or more warmer than 2013. However, when reviewing the tree ring reconstructions, you almost never see a temp variation from year to year greater than .3c

    Not to harp on the famous bristlecone pines, but my recollection is they did not pick up the north american heat wave of the 1930’s. But hey climate scientists note that would be cherrypicking.

  98. August 16, 2013 at 2:52 am

    If this is the basis of debunking Mann’s hockey stick, then one can only say it has been recreated using different methods with the same conclusions”

    The truth behind Mann’s hockey stick!

    [ http://www.youtube.com/watch?v=r9jtVZ3RUCU ]

    Well, that was disappointing. I waited for 4 minutes for him to give me something convincing that the hockey stick is legit and that temperature reconstructions like it are just as legit, but all I got was “Mann’s hockey stick is legit because other people did the same thing and got similar results.”

  99. Juice says:

    “…all I got was ‘Mann’s hockey stick is legit because other people did the same thing and got similar results’.”

    But Nature was forced to print a Correction to Mann’s Hokey Stick chart. If others got the same results, then they were wrong, too.

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