Another reason trees don’t make good treemometers – new tree ring data bias discovered

[Note: My first post in which I had written commentary mysteriously lost all of its content, posting nothing but white space. This is some sort of internal wordpress error, but has never happened before. I have some elements restored below, but my original commentary is lost. -Anthony]

I’ve written before about the difficulties associated with extracting a valid temperature signal due to all of the confounding variable in Liebigs law of the minimum, which I describe in detail here:  A look at treemometers and tree ring growth

Now a new confounding variable has been introduced that does not bode well for tree ring studies such as Mann et al.

Bishop Hill writes:

A new paper by Brienen et al in the journal Global Biogeochemical Cycles suggests that there may be a whole new set of biases in tree ring studies.

Tree ring analysis allows reconstructing historical growth rates over long periods. Several studies have reported an increasing trend in ring widths, often attributed to growth stimulation by increasing atmospheric CO2 concentration. However, these trends may also have been caused by sampling biases. Here we describe two biases and evaluate their magnitude. (1) The slow-grower survivorship bias is caused by differences in tree longevity of fast- and slow-growing trees within a population. If fast-growing trees live shorter, they are underrepresented in the ancient portion of the tree ring data set. As a result, reconstructed growth rates in the distant past are biased toward slower growth. (2) The big-tree selection bias is caused by sampling only the biggest trees in a population. As a result, slow-growing small trees are underrepresented in recent times as they did not reach the minimum sample diameter. We constructed stochastic models to simulate growth trajectories based on a hypothetical species with lifetime constant growth rates and on observed tree ring data from the tropical tree Cedrela odorata. Tree growth rates used as input in our models were kept constant over time. By mimicking a standard tree ring sampling approach and selecting only big living trees, we show that both biases lead to apparent increases in historical growth rates. Increases for the slow-grower survivorship bias were relatively small and depended strongly on assumptions about tree mortality. The big-tree selection bias resulted in strong historical increases, with a doubling in growth rates over recent decades. A literature review suggests that historical growth increases reported in many tree ring studies may have been partially due to the big-tree sampling bias. We call for great caution in the interpretation of historical growth trends from tree ring analyses and recommend that such studies include individuals of all sizes.

Presumably, this new source of bias applies just as much to tree ring studies where the increase in growth is ascribed to temperature.

==================================================================

Here is the abstract from GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 26, GB1025, 13 PP., 2012 doi:10.1029/2011GB004143

Detecting evidence for CO2 fertilization from tree ring studies: The potential role of sampling biases

Key Points

  • Observed increases in tree ring widths may be caused by sampling biases
  • Standard sampling methods lead to spurious trends in historical growth rates
  • Reported increases in ring width may often not be due to CO2 fertilization

Roel J. W. Brienen

School of Geography, University of Leeds, Leeds, UK

Programa de Manejo de Bosques de la Amazonía Boliviana, Riberalta, Bolivia

Emanuel Gloor

School of Geography, University of Leeds, Leeds, UK

Pieter A. Zuidema

Programa de Manejo de Bosques de la Amazonía Boliviana, Riberalta, Bolivia

Ecology and Biodiversity, Institute of Environmental Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands

Forest Ecology and Forest Management, Centre for Ecosystem Studies, Wageningen, Netherlands

Tree ring analysis allows reconstructing historical growth rates over long periods. Several studies have reported an increasing trend in ring widths, often attributed to growth stimulation by increasing atmospheric CO2 concentration. However, these trends may also have been caused by sampling biases. Here we describe two biases and evaluate their magnitude. (1) The slow-grower survivorship bias is caused by differences in tree longevity of fast- and slow-growing trees within a population. If fast-growing trees live shorter, they are underrepresented in the ancient portion of the tree ring data set. As a result, reconstructed growth rates in the distant past are biased toward slower growth. (2) The big-tree selection bias is caused by sampling only the biggest trees in a population. As a result, slow-growing small trees are underrepresented in recent times as they did not reach the minimum sample diameter. We constructed stochastic models to simulate growth trajectories based on a hypothetical species with lifetime constant growth rates and on observed tree ring data from the tropical tree Cedrela odorata. Tree growth rates used as input in our models were kept constant over time. By mimicking a standard tree ring sampling approach and selecting only big living trees, we show that both biases lead to apparent increases in historical growth rates. Increases for the slow-grower survivorship bias were relatively small and depended strongly on assumptions about tree mortality. The big-tree selection bias resulted in strong historical increases, with a doubling in growth rates over recent decades. A literature review suggests that historical growth increases reported in many tree ring studies may have been partially due to the big-tree sampling bias. We call for great caution in the interpretation of historical growth trends from tree ring analyses and recommend that such studies include individuals of all sizes.

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76 thoughts on “Another reason trees don’t make good treemometers – new tree ring data bias discovered

  1. Oooookay. Am I going nuts here,Anthony? I see a title,tags,posted in,etc,but NO story. Oy.Do I need more caffiene or watt?

  2. All that is showing right now:

    Another reason trees don’t make good treemometers – new tree ring data bias discovered
    Posted on March 20, 2012 by Anthony Watts
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  3. by my count tree growth is effected by at least 4 variables: sunlight, temperature, water and soil/nutrients … since we have no historical data for sunlight, water or nutrients it is impposible to calculate historical temperature using tree growth rates … impossible … Why is this still being debated by anyone ?

  4. in a previous thread, a poster worried that all science might be tarnished by the impacts of the bogosity that has overrun the field in the last 20 years.

    Well, all science DESERVES to be tarnished for having let this nonsense go on this far. This has happened because the scientific “establishment”, such as it is, has allowed it to happen and left it up to a handful of outsiders to point out what is wrong. Until “science” starts taking serious steps to point out how compromised this entire warmista project has been, they will be rightly seen as nothing but another special interest group packed with rent-seeking apparatchik’s willing to say and do anything for money and status.

  5. It’s worth noting that for all their self declared ‘vast knowledge ‘ there is not one amongst ‘the team’ who actual understand plant physiology well.
    We been here before of course with statistics, were people with far more expertise in an area can show us how the ‘the Team’ can be totally out of its depth and its only the arrogance ,that seems to be part of being a ‘climate scientists ‘, that stops them admitting it and accepting advice form those outside their little club.

  6. Anthony,
    Try the “Lazarus” add-in for firefox. If you are doing your wordpress editing from firefox, you will be able to recover text from various text boxes even if you have navigated away. The length of time to save is configurable. You want the status bar visible to do this. To recover text, just right click the same text box and see your choices of what has been saved. Mine is set to save for 4 weeks.

    Strangely enough, I just had to use it for this post since I wasn’t logged in to wordpress…

  7. Will Mann et al review this peer-reviewed paper? He should be e-mailed a copy and asked for his comments.

  8. If it’s too cold, trees have sluggish growth.
    If it’s too hot, trees have sluggish growth.

    That sort of sums it up, trees are not thermometer material

  9. Wait for the push-back, nothing these days must be allowed to challenge or interfere with our carefully constructed and cultivated tree rings. The ready response team’s “bogus is as bogus does team”, will fix this even if they have to turn the tree ring data upside down!!

  10. So many variables influence tree growth that one has to wonder if tree rings can be interpreted as proxies for anything. Nature is seldom as simple as some would like to think it is.

  11. I think we’ll get the standard “The science is settled” statements and the authors can look forward to people going through their trash looking for their connection to Big Oil. I suppose though that they’ll just use the new methodology and make up a fake document to ‘prove’ the link.

  12. Given the wide variety of influences on any growth of anything over time; it is simply a fools journey to do anything but the most generalizing about it. Add such confounding elements as variations in genetics and the variations of genetic responses to variations in stimulation… this is all simply a waste of time and time is money.

  13. Not sure what impact it has… but in reference to the figure, an R2 value of 0.39 indicates little/no correlation between the trendline and the data.

  14. My early career was a series of “discussions” with the PTB, at the time, that most of their sampling methods introduced so much error in their studies that they were worthless…(I was not all that popular, as you can imagine.) Once I started to produce reports that showed ways to save money by accurate and precise tests that were NOT biased by sampling error, it fixed a lot of problems. :-)
    That was in natural products so I can appreciate the difficulty inherent in dealing with anything that is hard to randomize when selecting samples. That does not, however, condone the practices of the GISS gang and their cohorts.

  15. Well, darn, I like counting tree rings. I remember being astonished once when a wind storm toppled two douglas firs that were the same size on my property. They were next to each other. One had thirty rings, one had sixty. I still don’t know how that happens.

  16. Note the article isn’t talking about temperature at all (or precipitation, etc.) — just CO2. Presumably this is because it can be pitched to counter arguments that CO2 is beneficial, and hence it qualifies as OK Sceance with the granters-that-be. Also note that it is modelling; no trees were actually harmed (cut or cored) to crank out this study.

  17. Let’s be scupulous here, this study is based on models: “We constructed stochastic models to simulate growth trajectories based on a hypothetical species with lifetime constant growth rates and on observed tree ring data from the tropical tree Cedrela odorata.” If we criticize the climate models for their weaknesses, we need to do the same here. This model very well may point out a new bias but we need much more proof that in fact it makes a difference. One might hypothesize that slow-growing old trees of the same species in the same climatic zone respond to environmental factors in relatively the same ways. If so, the bias of fast-growing young trees may make no substantial difference.

  18. Color me crazy but an interesting experiment would be to place a high resolution thermometer by a tree for about 20 years with a data recorder and then compare the derived vs actual temperatures?

    Just saying….

  19. I’m surprised we haven’t seen newspaper headlines: “Global warming causes trees to put on weight”?

  20. “Several studies have reported an increasing trend in ring widths, often attributed to growth stimulation by increasing atmospheric CO2 concentration.”

    That is the first time I’ve ever heard that. Ring width was always attributed to precipitation. What this means to me is that none of these “scientists” know what they are talking about and it is just another reason to be skeptical about anything they say.

  21. Tree ring data have many problems, not least biased sampling. The bias may be induced by the researcher or the very nature of the material examined as explained so well in this post. But tree ring data can be useful. In Baille’s work, he shows a narrow tree ring occurring over several areas in the first half of the 6thC which suggest a major event leading to global cooling (and destruction) for one year. This may be volcanic but Baille argues for an extra terrestial event backed up by ammonia readings in the Greenland icecores. The use of tree rings depends very much on the nature of sampling and the context (other links) into to which they are examined. Don’t reject tree rings out of hand. They must be considered scientifically (which I have to admit, certain persons have not).

  22. Couldn’t they have just asked a botanist? And I find this intriguing: “Reported increases in ring width may often not be due to CO2 fertilization”. The effect of CO2 on biomass is well established. Are they saying the rings, however, are not affected or the reportage is flawed?
    I get the feeling that the treemometer readings are about to get ‘homogenized” much the same way thermometers were. And the underlying data will disappear and the past will have been much colder.

  23. was said, “Until “science” starts taking serious steps to point out how compromised this entire warmista project has been, ”

    Unlikely to ever happen as they would also be admitting to knowingly wasting (stealing) many billions. We would and should have to sue them for every penny to be returned, even if they have to hock their future generations that they were planning to cook with global warming.

  24. spence says:
    March 20, 2012 at 8:55 am

    On the contrary, trees might work as a themometer if you find a location where conditions are always on only one side of the tree growth rate optimum (inverted U shape response curve). Danger Will Robinson. If temperature transgresses during some period of time to the other side of the optimum, the data may appear to indicate the opposite condition. Thus, you would need to compare multiple locations further away from the optimum growth conditions to determine whether warming or cooling occurred at some time in the past. Gosh this isn’t so hard. Let’s just model it. Why should we bother with sampling? ;->

  25. It goes without saying wordpress must die. That said the evidence is equally as compelling that climate alarmism must die. Publication bias exactly parallels the tree ring data. The fast growing but unrepresentative elements of emerging climate science get undue attention while the longer lived yet less attention grabbing elements such as solar output, cloud cover, orbital divergence, etc. continue to explain ever more of the totality.

  26. Well, yes, that’s just one more reason why people should regard treeometers as a work of fiction. Biases, environmental factors for growth, and the fact that the trees only grow 6-8 weeks out of the year and cannot possibly be representative of the year except by chance, means that all of this madness needs stricken from the books and people should be made mockery of to the point of shame.

  27. You know, I have had internet hook-up problems through Firefox, ever since I let it talk me into updating to FF10. Haven’t done the upgrade to 11 yet. Symptoms are – can’t hold or loses logins, won’t go off to urls, etc , having to reload and recycle urls to get the browser to address the web. Additionally, I recently added Facebook hookups too, and when Facebook is online with me, it gets in the way of a lot of link completions. Facebook and wordpress are not happy together – WP admits it. You might be running into issues if you’re autoposting to Facebook. I do on my systems, depending on which email address is logged in to FB (paging purposes).

  28. Nothing particularly wrong with wordpress – its all of the corporate data miners it has to interract with that cause most of the problems.

  29. Re:

    Max Hugoson says:
    March 20, 2012 at 8:09 am

    All that is showing right now:
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    You’re doing better than I. Last weekend, Mark Zuckerberg’s smiling, youthful visage popped up onscreen below the opening post, urging me to get in on some deal “before Facebook goes public”… thought I was in a time warp. [With all the money Zuckerberg made, you'd think he could clean up some of that cr*p!]

  30. This is a baseless and fraudulent attack on my son. The conclusions the authors have come to are without foundation. My son’s data, which the authors sought repeatedly and which he refuseed to give them, shows clearly that they are mistaken. I can only assume that this is a witchunt against my little boy planned and paid for by Big Al (sorry, Oil). I can assure you that my son will immediately seek the dismissal of these authors from any posts that they have in which they might earn their meagre living. He will also be asking Phil Jones to email his son to see if he knows these charlatans so that pressure can be applied from above. There is a silver lining, I suppose. My boy will now be able to tour lecturing on why he is a victim of these nasty nasty people.

    I myself will personally get straight on to that nice water expert and ask him to get to the heart of this scurrilous slur as quickly as possible. He has proved quite reliable recently in obtaining dirt on evil people likek this.

    Did I mention that my little cherub is a climate change hero?

  31. The decline of “hide the decline” fame was almost certainly the result of two things, (1) some sort of sampling bias very much like what is described here, and (2) a growth curve standardization algorithm that apparently overcompensated for the bias on the outermost rings of the youngest trees in the population. Layman Lurker and Dr. Mauri Timonen have done quite a bit of excellent work on this puzzle, but it remains somewhat less than fully resolved AFAIK.

  32. Dennis Wingo (@wingod) says:
    March 20, 2012 at 9:30 am

    Color me crazy but an interesting experiment would be to place a high resolution thermometer by a tree for about 20 years with a data recorder and then compare the derived vs actual temperatures?

    Just saying….

    If you want to do this properly, find a statistically valid number of similar pine plantations – we use to have them up here, but they’ve fallen out of favour – plenty still around. Equip about 100 trees in about five(?) plantations with instrumentation that measures continuously ambient temp, absolute humidity, rainfall, and photometry, and run it for about 5 years. Core them all at the start and at the end in the same location. Pick trees of the same DBH within each plantation, and with the same ambient light level, and no tree should be further than 50 feet from one another – ideally the array of measured trees would be spatially even.

    Then, you might have some idea of what correlates with what.

  33. “Presumably, this new source of bias applies just as much to tree ring studies where the increase in growth is ascribed to temperature.”
    Not really. The bias attributed to temperature is for 2 reasons only….money and power. Or maybe the fact the “scientists” tried to use ONE sample out of how many billions of billions of samples possible/available?
    My only gripe…why the heck did they have to use a model(for above study)? sigh

  34. I proposed this kind of sampling bias mechanism on a CA thread more than two years ago. (Pats self on back.) I’m happy to see that someone had the same idea and actually developed it into a paper.

  35. This article will have no effect on Mann’s perception of the significance of his own work.

    After all, he didn’t do the sampling (It’s soooo difficult to update chronologies, ya know, unless you’re Steve McIntyre with a Starbucks in hand)

    And he can still rely on the Tiljander sediment proxies, even if he did use them upside-down

    “Robust! Robust, I tell you!!”

  36. Gary says:

    Let’s be scupulous here, this study is based on models: “We constructed stochastic models to simulate growth trajectories based on a hypothetical species with lifetime constant growth rates and on observed tree ring data from the tropical tree Cedrela odorata.” If we criticize the climate models for their weaknesses, we need to do the same here.

    You are talking about two completely different kinds of “models”. Climate models are intended to replicate real world conditions from the past, and are held to be predictive of the future. That is what we normally think of when we say “modeling” in the context of climate discussions.

    The “models” discussed here are entirely different. They are not attempting to replicate anything in the real world, and certainly not to predict anything about the future. What they are doing is creating a hypothetical circumstance, and using it to test the denrdro sampling methods. It is very much like feeding Mann’s algorithym with Major League Baseball scores, and checking to see if it produces hockey sticks.

    This model very well may point out a new bias but we need much more proof that in fact it makes a difference. One might hypothesize that slow-growing old trees of the same species in the same climatic zone respond to environmental factors in relatively the same ways. If so, the bias of fast-growing young trees may make no substantial difference..

    Their point has not anything to do with comparisons between slow growing trees. The question is: what if fast growing trees have shorter life spans than slower growing trees? How would that effect dendro reconstructions? Answer: Fast growing trees would tend to be underrepresented in the early time periods, as those trees would have died before the sampling event. The closer to the time of sampling you get, the higher the proportion of fast growing trees that get included in the sample. This would make it appear that growth rates are increasing, even when they are not.

    Ditto the question about big tree bias – if your sampling scheme only uses trees that are larger than some minimum size, how might that effect results? Answer: Disgarding small trees from your sample removes young trees that are slow growing, but keeps young trees that are fast growing. This causes fast growing trees to be overrepresented in the more recent time periods of the sampling. This would make it appear that growth rates are increasing, even when they are not.

    The only purpose of the “stochastic models” used here is to quantify the potential magnitude of the bias in the results produced by these sampling methods, by feeding those methods a dataset with known properties. They aren’t “models” in the same sense that we use when referring to climate models.

  37. More than a decade ago, I read a Nat Geo article on wet and dry cycles in the American Southwest, using bristlecone rings as proxies; wide = wet. By chance, the same month, I saw a study (don’t recall the peer-review pub.) using the same area, same trees as proxies for heat cycles; wide =hot. I haven’t trusted dendro-proxies for anything since.

  38. Dennis Wingo (@wingod) says:
    March 20, 2012 at 9:30 am

    Color me crazy but an interesting experiment would be to place a high resolution thermometer by a tree for about 20 years with a data recorder and then compare the derived vs actual temperatures?

    Just saying….

    This has been done. This is what “The Team” refers to as “the divergence problem.”

  39. woodNfish said @ March 20, 2012 at 9:34 am

    “Several studies have reported an increasing trend in ring widths, often attributed to growth stimulation by increasing atmospheric CO2 concentration.”

    That is the first time I’ve ever heard that. Ring width was always attributed to precipitation. What this means to me is that none of these “scientists” know what they are talking about and it is just another reason to be skeptical about anything they say.

    Try these:

    Graybill, D.A. and Idso, S.B. 1993. Detecting the aerial fertilization effect of atmospheric CO2 enrichment in tree-ring chronologies. Global Biogeochemical Cycles 7: 81-95.

    Idso, S.B. 1995. CO2 and the Biosphere: The Incredible Legacy of the Industrial Revolution. Third Annual Kuehnast Lecture. Department of Soil, Water and Climate, University of Minnesota, St. Paul, MN.

    LaMarche Jr., V.C., Graybill, D.A., Fritts, H.C. and Rose, M.R. 1984. Increasing atmospheric carbon dioxide: Tree ring evidence for growth enhancement in natural vegetation. Science 225: 1019-1021.

  40. Dennis Wingo (@wingod) says:
    March 20, 2012 at 9:30 am
    Color me crazy but an interesting experiment would be to place a high resolution thermometer by a tree for about 20 years with a data recorder and then compare the derived vs actual temperatures?

    ////////////////////////////////////////////////////////
    QUite so.

    However, we almost certainly know the result since this is, in effect, the subject of hide the decline. As from 1960 onwards, tree ring data does not match the instrument temperature record post 1960 when the tree ring proxies are tuned to the instrument temperature data for the period about 1905 to 1960. This comfirms that tree rings are not good temperature proxies and ‘the Team’ were well aware that they were not good temperature proxies but still pushed ahead with their reconstruction of temperutures going back to 1300AD then back to about 1000AD.

    One thing that occurs to me is whether Mann’s work should be brought up to date following all the revisions to the GISS and Hadcru data sets. As I understand matters, his (and Briffa’s) tree ring proxy was tuned to the instrument record for the period ~1905 to ~1960. Well these temperatures have been revised quite a bit this last decade. They have been revised downwards (and post 1980s upwards). How has this affected the calibrtation that he used? And would the decline, ie the difference between tree ring results and instrument record for the period post 1960 be even greater? The hide the decline could now be worse than we think!!

  41. At the back end of my garden, I have 3 tallish pine trees growing within about a metre of each other. One is considerably older but two are about the same age, within a year or so. I recall them as small saplings about 10 a foot high when I bought the property.

    These two small trees are broadly similar height but one has a trunk which is about 50% bigger than the other. The reason would appear to be that the smallest is in the shade of the other two. This has not adversely affected its height, but has had a dramatic effect on its girth. Of course one might be a slow grower and the other a fast grower, but I suspect that they both seeded from the same tree and are therefore likely to have similar DNA. My guess is that it is a light issue, although it is possible that there is also competition for rainfall/soil moisture. The stark differenc ebetween these two trees does illustrate why trees are unlikely to be good proxies for recording temperature.

  42. What? No comments by Hugh Pepper? Certainly he’ll say Mann has already covered this in the book that I (and everybody else) should read. Mann the tree ring circus hero–again performing a death-defying leap over logic and verifiable science.

    At least it makes great theatre for those hooked on the CAGW circus.

    But no, Hugh–I don’t have to read Mann’s most recent book to know everything I need to know about Mann. That has been made perfectly clear to me from what other honest researchers have said about his methodology.

    And no, I don’t believe Mann has invented another type of statistics–well, let me clarify that: He’s “invented” something alright, but it isn’t statistics.

  43. There are plenty of reasons for people (here) to continue to study trees in climate.

    Backpack the high passes in the Rockies, and above 11,000 feet or so, you’ll see the skeletons of trees that lived and died. Take a moment to realized why they stand out: they are high above current timberline. Some of the bigger relict bristlecones are more than two feet in diameter, sunbleached, lying where they dropped, probably several hundreds years ago, like pieces of driftwood thrown up by the high tide of the last millennium. Whether it was warmer temps or moister soil that allowed them to achieve that elevation, their living descendants can’t and don’t – the present forests of bristlecones are hundreds of vertical feet below.

    I cored a few of the standing trees (mostly smaller than the those that died higher up) and, one dated to 1440 at the pith. Some of the dead trees had undoubtedly been there for centuries, so their lives may have overlapped, but the clear space – of scrub oak and tundra – between them is telling. If the fallen giant had comparable age when it fell, it was a seedling around the 1200’s. You don’t need to argue the significance of tree ring widths for this – just count the absolute years (it takes a hand-held magnifier) and use your reasoning to infer what it means.

    Maybe someone here can tell me I’m crazy, because otherwise I consider the implications of this clear.

  44. There is unrest in the forest
    There is trouble with the trees
    For the maples want more sunlight
    And the oaks ignore their pleas

    Words from a song by Canadian rockers Rush. Tree proxies have many more variables than temperature alone. Makes me suspicious that they’re proxies for a cause, not a climate.

  45. dorsai123 says:
    March 20, 2012 at 8:32 am
    by my count tree growth is effected by at least 4 variables: sunlight, temperature, water and soil/nutrients
    —————————

    Plus disease, fungi, parasites, fire, lightning, windstorms, (natural) acid rain, and likely several more variables. It is beyond ludicrous to believe you could reconstruct local temperatures based on tree rings, and completely absurd to use them as a proxy for global temps.

  46. I thought it was well known that slower growing trees were more “dense” than fast grown trees. Surely, it is therefore likely that slow-grow trees will show up more in the archaeological record than faster trees.

    Another thing is that far more trees were cultivated in the past than people are willing to admit. So, even in apparently “natural” woodlands, trees will be cultivated with an effect on tree growth rate.

  47. Neophyte says:
    March 20, 2012 at 3:12 pm

    There are plenty of reasons for people (here) to continue to study trees in climate.

    Backpack the high passes in the Rockies, and above 11,000 feet or so, you’ll see the skeletons of trees that lived and died…..
    ________________________________________________
    Tree line advance and retreat at high altitudes is a decent proxy for temp/growing conditions. It is a heck of a lot better proxy than tree rings. Also used is the extent of other plant species. Orange groves in Florida for example. History of Florida’s Citrus Groves

  48. Before dismissing all tree-ring studies, it might be worthwhile to consider the recent study published by the Chinese. Their study of trees on the Tibetan plain showed a different result than what Mann found. They DID pick up the LIA, and the MWP. What they did NOT pick up was a hockey stick.

  49. And this means nothing to global warming believers and their politics. The Mann Hockey stick will still be said to be very solid science.

    Get ready for the poorly thought out rebuttals to this work to be posted on some web site and quoted verbatim everywhere on the web.

  50. Another factor that impacts tree ring growth is the proximity of other trees and plants. And like the other variables mentioned, there is simply no way to take that into account over tens or even hundreds of unobserved years.

  51. Dendrochronology is a vegetarian form of Extispicy, and works just as well.

    ——————————————————————————–

    Extispicy

    The term is derived from extra and spiere, meaning to view or consider. It applied cheifly to the inspection of entrails for the purposes of augury.

    The practice of extispicy came to the Etrurians from the Babylonians as most forms of divination were derived from Mesopotamia. The practiced also was employed throughout Greece where the priesthood was confined to two families.

    The Roman auspieces had four distinct duties: to examine the victim or animal before it was opened, to examine the entrails, to observe the flame of the sacrificial fire, and to examine the meat and drink offered in accompaniment of the sacrifice.

    It was a fatal sign when the heat of the fire was wanting. This occurred when two oxen were immolated on the day Caesar was killed.

    Signs predicting a potential instant disaster were if the priest let the entrails fall, if there was more bloodiness than usual, or they entrails were of a livid color.

  52. One phenological phenomenon going on right now in Washington DC is the Centennial (100-year) Cherry Blossom Festival.

    http://www.nationalcherryblossomfestival.org/about/bloom-watch/

    The Japanese trees sent in 1912 are reaching “full blossom” this week. The claim is that the warmer the springtime and preceding winter, the earlier the blossom. So, with an unusully early bloom this year, the warmists are making the most of the moment.

    The buds typically appear in late February – early March, and petals bloom fully by early April. But over the last century, there have been at least six early blooms comparable to or earlier than this year’s: 1920, 1926, 1944, 1976, 1990, and 2000.

    http://www.washingtonpost.com/blogs/capital-weather-gang/post/dcs-cherry-blossoms-have-shifted-5-days-earlier-in-last-90-years-what-about-the-future/2012/03/16/gIQARvtTPS_blog.html

    With no record of the blossom dates between 1912 and 1919, and the recent warm-weather blooms, this Washington Post environmental writer apparently feels justified in extrapolating his declining line out into the 22nd century when cherry trees will be blossoming at Christmas.

    It never ceases to amaze me that there are people in the world whose florid fantasies are fuelled by the banal and beautiful coming of springtime. This year’s relatively early bloomtime seems to have unleashed people’s imaginations.

    Reports last night on the News Hour, and in various Washington papers predict more and more precocious blossoms… on into the future.

  53. dorsai123 says:

    by my count tree growth is effected by at least 4 variables: sunlight, temperature, water and soil/nutrients … since we have no historical data for sunlight, water or nutrients it is impposible to calculate historical temperature using tree growth rates … impossible … Why is this still being debated by anyone ?

    Tree rings only record growth on one part of a tree. Trees can vary in growth of leaves, branches, fruit, etc from year to year.

  54. KNR says:

    It’s worth noting that for all their self declared ‘vast knowledge ‘ there is not one amongst ‘the team’ who actual understand plant physiology well.
    We been here before of course with statistics, were people with far more expertise in an area can show us how the ‘the Team’ can be totally out of its depth and its only the arrogance ,that seems to be part of being a ‘climate scientists ‘, that stops them admitting it and accepting advice form those outside their little club.

    As shown by the attitude “If your not a climate scientist you are not qualified to comment at all”.
    The obvious question then being what is “the team” actually well qualified in…

  55. My personal favorite “un accounted tree ring bias” is the Bear Poo Problem…

    In the Pacific Northwest, at least, a very large part of the nitrogen delivered into the forest is from bears eating fish. And bears, after catching fish, like to take them over near a tree, where they eat some and leave some. Then, time passes, and so does the, er, bear dinner… when the bear is even further from the stream.

    Bears like to, ur, “use” a tree then….

    So, if a bear poos in the forest, does anyone counting tree rings notice?

    As folks don’t like to be eaten by bears, we tend to kill them. Bear populations vary inversely with human hunting.

    All this means that to properly calibrate your tree rings, you really must now what the bear population was and how much “bear poo” was “deposited” on those particular trees. Which varies with human population, fish runs, water in the streams, bear populations, and weather.

    Or, in summary, “Poo Happens” and you need to know just how much it happens…

  56. Yup that is what we need. Another adjustment, from Mannian forces, to the tree ring data to show how much near the boiling point of water, we will soon be.

  57. Neophyte says:
    March 20, 2012 at 3:12 pm

    There are plenty of reasons for people (here) to continue to study trees in climate.

    Backpack the high passes in the Rockies, and above 11,000 feet or so, you’ll see the skeletons of trees that lived and died.

    I noticed the high percentage of dead pinion pine trees in several mountainous areas where I’ve worked as a geologist and upon close inspection, found the vast majority displayed blackened trunks and limbs–obviously the victims of lightning strikes. I’ve also scurried from these locations several times as summer thunderstorms generated such intense lightning displays that it sounded like one continuous peal of thunder–no wonder there were so many dead, charred trees. I also wonder what impact all that lightning has on the growth rate of trees–obviously those receiving the full brunt are terminated but those around the strikes would also be affected.

  58. Anthony,

    RE: WordPress dumping your original post.

    I’ve noticed this happening to my posts recently, too. In my case, I have discovered that if I leave a New Post page up overnight and then use that same New Post page to write a post in the morning, the entire post gets eaten by the “NETherworld monster.” The solution, at least for me, has been to start out with a fresh New Post page whenever writing. If I am writing something late at night and I haven’t finished it, I save it as a Draft and then edit that draft in the morning when I wake up. So far, that seems to have kept the NETherworld monster at bay—knock on wood rings…

    Cheers

  59. RE: WordPress : the rule is always write in a backed up way, by either typing into a text editor ..preferably with autosave on, or something like Yahoomail which also autosaves drafts as you type. (actually Chrome is quite good at keeping form data, often when I click back the typing is still there)
    sorry for you Antony…. it’s an awful feeling when it disappears & you have to type it all in again.

  60. [Note: My first post in which I had written commentary mysteriously lost all of its content, posting nothing but white space. This is some sort of internal wordpress error, but has never happened before. I have some elements restored below, but my original commentary is lost. -Anthony]

    Yeah, that just happened to me twice on comments. I don’t think I am going to post on my blog for a day or so…

    Steve Garcia

  61. This seems to argue that the Divergence Problem doesn’t exist – that the tree-rings still tell everybody the temps are going up. WTF is with that? Don’t they pay attention to the actual dedroclimatology crisis?

    Steve Garcia

  62. @Stew Green (@stewgreendotcom):
    “RE: WordPress : the rule is always write in a backed up way, by either typing into a text editor”

    Yeah, but for the entire time WUWT has been here – YEARS – it never blanked stuff out before. It gave a sense of false security.

    It is probably as well with my comment on another thread, because I ripped into a guy a LOT. Not my style really…

    So everyone here can still think I am not an a**hole. So some good came of it!

    Steve Garcia

  63. @Anthony, feet, steve;
    If you are writing with the Firefox browser, install Lazarus, and it saves all typing in its own data base, searchable and with page links. Use version 2.x; less flexible but still effective 3.x versions for Safari and Chrome. The 2.x version allows modification of the default 14-hr ‘save’ period. I set mine to 54 weeks. :)

    A true a**-saver.

  64. feet2thefire says:
    March 21, 2012 at 5:39 pm

    @Stew Green (@stewgreendotcom):
    “RE: WordPress : the rule is always write in a backed up way, by either typing into a text editor”

    Yeah, but for the entire time WUWT has been here – YEARS – it never blanked stuff out before. It gave a sense of false security.

    It is probably as well with my comment on another thread, because I ripped into a guy a LOT. Not my style really…

    So everyone here can still think I am not an a**hole.
    So some good came of it!

    Steve Garcia

    And whatever gave you the idea any of us had that misapprehension?
    >:p

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