Pielke Senior on tree and thermometer divergence

by Dr Roger Pielke, Sr.

With the McShane and Wyler paper examining and questioning the method, this look at the proxy data and its problems seems like a relevant issue to review.

Comment On Tree Ring Proxy Data and Thermometer Type Surface Temperature Anomalies And Trends

There was an interesting conclusion in a New York Times article on the relationship between tree ring proxy temperature trend analyses and thermometer type measures of temperature anomalies and trends.  The article is

British Panel Clears Scientists by Justin Gillis published on July 7, 2010

The relevant text is on page 2 it is written

“But they were dogged by a problem: Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries. If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.”

There are, however, problems with this conclusion. Since the thermometers are not coincident in location with the tree ring data (in the same local area), it would not be surprising that they are different. Indeed, this is yet another example that implies unresolved biases and uncertainties in the surface temperature thermometer type data as we discussed in several of our papers (see and see), as the thermometers are measuring elsewhere then where the proxy tree data is obtained.  This obvious issue has been ignored in the assessment of this so-called divergence between the two methods to evaluate temperature anomalies and trends.

It is possible, of course, that the trees are responding differently due to the biogeochemical effect of added carbon dioxide and/or nitrogen deposition. Nonetheless, to accept the thermometer record as the more robust measurement of spatial representative temperatures is premature.

I have discussed this issue further in the posts

Comments On The Tree Ring Proxy and Thermometer Surface Temperature Trend Data

December 2007 Session ‘The “Divergence Problem’ In Northern Forests

A New Paper On The Differences Between Recent Proxy Temperature And In-Situ Near-Surface Air Temperatures

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136 thoughts on “Pielke Senior on tree and thermometer divergence

  1. Restating the obvious: since tree rings respond to lots of things, like sunlight and moisture, it seems odd to me that they matched temperature trends at all. Particularly in ‘previous centuries’. Just how in the {snip} did they measure temperature in ‘previous centuries’? (what made that proxy so good?)
    Seems like a lot of assumptions, and facts not in evidence. Or just Bad Science.

  2. Excellent snark sir. May I suggest that the supremacy of trees be vetted by an unbiased panel of Druids?

  3. In retrospect, trees are terrible proxies. Many botanists have commented on the problem. Insect, fungus, bacteria, drought, flood, rock slides, avalanches, wind, are all unrelated to temperature. Frankly, the proxies are likely falsified through the entire course. It was when temperature and correlation became possible the panic started. It was all BS to begin with.

  4. I fail to understand the great faith in tree rings as temperature proxies. Trees do better in warm years than in cool years. Trees do better in wet years than dry years. Do they do better in warm dry years than in cool wet ones?
    A close look at the rings in Dr Mann’s glamour shot show that a core taken from different azimuths can give you very different ‘temperature’ readings. Or maybe different rainfall readings. They can even give you different ages.
    Whatever they show, they show it only for daytime, and only for part of the year. And they sure didn’t mysteriously stop showing it in 1960.

  5. “Nonetheless, to accept the thermometer record as the more robust measurement of spatial representative temperatures is premature.”
    Interesting. Perhaps the tree ring results which show cooling in the area should be incorporated into the temperature record “from 1960 forward”.

  6. Trees like CO2 rather a lot. Next to a coal fired power station growth rate was found to triple. If the growth rate is x3 then the trees’ rings are thicker. Amazing!

  7. Yes…yes…here we were, going merrily, merrily for thousands of years with the tree rings being the best of the best temperature proxies until in 1960 they weren’t. I blame the thermometers, and the mystery. It’s a mystery, my friends, so methinks a novel is in order. A climate change novel, with a movie based on it. Quite an idea!

  8. “Since the thermometers are not coincident in location with the tree ring data (in the same local area)”
    Boy, stunning that such close proximity calibration hasn’t been done. How hard would it be to puta thermometer in the woods and actually callibrate tree ring data to exact temp? Or do tree ring analysis in woods near a well-sited thermometer with a long term record?
    Not glorious work, but how impotent to do.

  9. I was born in 1960 and I deliberately caused the divergence problem because I thought it might be fun.

  10. I will consider the possibility that dendroclimatology is worth even looking at when someone can provide me with a description of the exact physical mechanism by which a tree can encode a record of the ambient atmospheric temperature of the vicinity where it grows, which is even remotely plausible. Until then, if you come bearing tree ring proxies, just keep walkin’, cuz I ain’t interested.

  11. Everyone knows the trees were there in the 60’s so no wonder thay can’t remember the temperature…..man.
    Which is as supportable as any theory that tree rings are a useful proxy for temperature.

  12. Wow, relevant comments with some humor mixed in. What a nice contrast to the hockey stick thread!
    I’m amazed people still give any credence to tree rings as proxies for temp. As stated, there are so many variables that combine for the make up of a tree ring, it is impossible for me to believe anyone can reasonable discern what is temp in the tree rings and what is not. Of course, if I cared to figure out the mystery of divergence, I’d look for an event that occurred near 1960. I don’t buy the CO2 and/or nitrogen theory, because if they can indeed discern temps from the tree rings, surely they’d be able to discern known substances that directly effect tree growth. If they can’t do that, then it is just more evidence that tree rings as proxies are as reliable as reading tea leaves. Further, given the hyperbole surrounding CO2, I think if there were even a remote chance CO2 were the culprit, we’d all already heard about it.

  13. “…..but they were dogged by a problem: Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries….”
    Since around 1960, trees have stopped responding to ADJUSTED temperature increases.
    fixed

  14. Mike McMillan says:
    A close look at the rings in Dr Mann’s glamour shot show that a core taken from different azimuths can give you very different ‘temperature’ readings. Or maybe different rainfall readings.
    Not only is this tree trunk more “egg shaped” than round it also shows very asymetric growth patterns in some years. Especially when young. Can’t really see how either temperature or rainfall could account for this. An alternative possibility would be shading from other trees restricting where this tree can put its branches and leaves, this needing more mechanical support in the trunk. However as it became more mature factors such as pervailing wind and direction of sunlight became more important.

  15. Bruce of Newcastle says:
    Trees like CO2 rather a lot. Next to a coal fired power station growth rate was found to triple.
    Not really much of a suprise. Given that market gardeners have discovered that putting carbon dioxide into greenhouses increases yields.

  16. Yeah, but it was the sixties, flower power and The Beatles, and they were “cool”, no wonder the trees stopped growing.

  17. “Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries.”
    This sort of moebius lie is acceptable? ?
    I call ‘loco como mierda de murcielago’

  18. The idea that tree rings can be used as a temperature proxy is so preposterous it shouldn’t even be on the table.
    And anybody who claims to be able to measure rings to a hundredth of a mm should be locked up…
    The fact that anybody is still talking about this is a triumph of intellect over intelligence!

  19. The most prominent input to tree ring growth is atmospheric CO2 content. It is also problematic that some scientists insist that global temperatures have increased as shown by thermometers (after much fiddling with the data) and now consider that tree rings are wrong for the last 50 years when temperatures have actually shown a leveling then slight fall. But we must not be diverted from our forward march by data we do not like.

  20. Until there are thermometers co-sited with the trees to be examined we can make no reliable deductions at all Mr Goddard – concerning the so called DP. Once the divergence problem was identified I would have thought that placing thermometers beside subject trees for long term evaluation would have been the first and most obvious response. If it hasn’t been done, now would be a good time dear “scientists”, and a wee bit further down the line you can make your deductions on the divergence problem based on relevant and useful data analysis, and also of course on the long term record. But, surely, this process has already been started. If not then we should pull out all interested climatologists by their rotten roots and have them replaced by proper scientists, or even rational human beings . . . .

  21. Until there is a full confirmation by experiment of a Theory for the divergence the only explanation for the divergence is that trees do not react to higher temps post 1960 and never have before 1960. So until this tested theory is available using trees as a temp proxy will not work as high temps are unrecorded hence the Hockey Stick.

  22. For all the ills of being poorly correlated to temperature, tree rings studies in places like the Pacific Northwest, where some species go back 2,000 years, events such as the Roman Warm period, MWP and Little Ice Ages are well depicted. They also show off Super El Ninos, putting 1998 in it’s place…down the list.

  23. Oops, sorry, the above tree ring data series was done by Cook. Couple of nice videos of each year plus a comparison with temp data.
    Today’s rough climate is tame by comparison to events of the last 2000 years.

  24. Why look at the trees being the problem, couldn’t it be the thermometers’ fault?
    Maybe since the 1960s thermometers have been giving inaccurate readings of temperatures, after all the tree ring based temperature record is 1500 years long and only had a problem in the last 50 years (about 3% of the record) while the thermometer based temperature record is only about 150 years long so a whole 1/3rd of that record doesn’t match the tree ring record. Overall it seems more reasonable to assume that thermometers are just a poor means of measuring temperature thus the unreliable thermometer data should be thrown out in favor of the tree ring data.

  25. There is a saying, “putting the cart before the horse”.
    Climatology is full of examples.
    It seems that they have not heard of the word “calibration”. All thermometers are proxies of the temperature T which enters into equations. ALL
    Some are more accurate proxies than others.
    Take a mercury thermometer, and calibrate it the standard way : 0 at ice melting point and 100 at water boiling point at 1 atmosphere. That is the Celcius scale, and can be very accurate.
    One now has a thermometer to calibrate against for less accurate proxies.
    The scientific method for calibrating tree ring width to be used as a thermometer would require a statistically significant sample of tree samples from a region where there are thermometer readings for a number of years.
    Where is this calibration curve?
    The defect of the tree ring studies is not only that they compare the tree proxy temperatures to average globe temperatures, but that they have not demonstrated a calibration curve .
    Putting the horse in front of the cart the fact that there is a decline after 1960, according to the logic of the anomalies, should have shown a decline in the more accurate thermometer readings. The decline in the tree ring proxy data demonstrates that the tree rings are not thermometers.

  26. “…trees have stopped responding to temperature increases in the same way they apparently did in previous centuries…”
    No they did not respond that way for “centuries” . Temperature records started only around 1850, and divergence problems before that period may have been just as common as they have been after 1960.
    The best answer is still that tree rings are very poor temperature proxies.
    The second best answer is that temperature records may be corrupt as well.
    But Gillis’ assumption that tree rings responded to temperature variations for a thousand years and then in 1960 suddenly atopped to do so is embarrassing junk.

  27. It really is very simple.
    If you “lose temperature sentativity” after a certain date, you cannot under any circumstances be certain that it EVER had ANY temperature sensativity to begin with. I do not understand why that is so difficult to understand.
    Trees make horrid thermometers.

  28. I’m well kitted-up in a kevlar suit and tin helmet before I say this but ….
    Is there any mileage in the hypothesis that tree rings may well be a lousy proxy for temperatures but that they could be a fair proxy for climatic conditions in general?
    Most people, certainly on the sceptical side of the argument, appear to believe that there is more to climate change than temperatures alone. If there is a “divergence” around 1960, why would that be? And would it tell us anything important about the current state of the planet?
    I only asked … 🙁

  29. As a biologist, I will say for the umpteenth time, individual trees in the wild cannot be used for temperature proxies. Even a first year biology student, with a little reflection, can explain why. The short answer is that every tree grows in a unique ecology, sufficiently different from its neighbour to render the proxy data unquantifiable for small populations. A sufficiently large population of tree samples can point to gross local events such as large scale fires, droughts or similar events, but to look at climatic variables you have to look at forests, not trees.
    This underpins the entire problem with using complex organisms as proxies for anything. Their inherent adaptability makes them unfit for the role. Its not until you can begin to evaluate the response of the population can you begin to approach any kind of statistical significance to certain measured results, and even then, with great risk. Complex biological systems are inherently chaotic. Identifying confounding variables is often a bigger problem then accurately measuring certain parameters. Complex organisms and their behavior is the result of a bewildering number of multi-causal, multi-variable effects.
    From my very first year uni programs, its been clear that the physical sciences pursued by my student colleagues have always had a poor scientific appreciation of the nature and complexity of biological systems (aided, I suppose, by the late night beer sessions explaining to my engineering buddies just how it was their girlfriend got pregnant…). Mostly I chalked this up to significant lack of training in the biological sciences as they pursued their interest in the relatively simplistic (if not indeed, simple) narrow world of physical and mathematical problems. The result is the kind of worthless science produced by the current crop of “climate scientists”, which is at best , simply intellectually naive, and at worst, dangerously agendized. It pains me to see colleagues climbing on the agenda bandwagon promoting the thin-on-the-ground attitudinal bio-proxy science that is turning up. Science education is, I believe, in crisis. Not only so in the agendas that drive much of it, but in the fundamental training biology students are receiving – they simply are not getting an adequate foundational basis on what life is, a knowledge that comes from things like the “old” disciplines of comparative anatomy, phylogenetic analysis, physiology etc.
    In order to model anything, you first have to know what it is you are modeling. I believe science education has failed miserably in preparing students how to come to know about what they are doing, preferring instead to dazzle them with the bright lights of technology, rather then the bright spark of intellectual realization. The end result is the present morass of intellectual fluff being posited as grand revelations on the future of the planet.

  30. Hi there!
    Well I wonder why a layman as me react to the most obvious basic contradictions
    in cliamate proxies.For six month I wonder what the climatehistory would look with out tree ring proxies removed. What does the hockeystick and all the climatic conclusions look like without them? For me this is defenitely a “its much vorse than I thought” that this obvious circumstances doesnt hit the table until now!

  31. Proxies are theories for replacement of missing data that cannot be recovered by the past as measurements were not available.
    Widely used by scientists and a good source of funding to continue the theoretical area.

  32. The idea about treemometers is that only trees which are growing in certain limited an more or less stable conditions may respond predominantly to temperature as a main factor. The bristlecones are constantly water and nutrient-limited, the Siberian trees have a constant abundance of water (no limit there) but their growth occurs only during one month in summer.
    BTW – the Russians, when they write themselves about their tree rings, are very careful to point out, that the trees are a proxy for summer Siberian temperature. Not much talk about global temp here…

  33. My simple point has always been to point at the elephant in the room.
    If tree ring data was adequate prior to 1960 then why are they not adequate after 1960? [diverged from thermometer data]. Fine, so what degree of confidence should I have on tree ring data prior to 1960?
    In my simple mind one of the measurements is most likely producing erroneous data. UHI, “biogeochemical effect of added carbon dioxide and/or nitrogen deposition” and geographic locations only complicates matters further.

  34. Botanists have told climatologists that tree growth is not dependent on temperature so the use of tree rings as temperature proxies is unsound.
    Statisticians have told climatologists that their use of statistics is flawed both in methodology and sample sizes.
    Yet climatologists continue despite this expert advice to use tree ring temperature proxies and flawed statistics based on insignificant samples to support wild unvalidated claims.
    Is there any other branch of science where these behaviors would be accepted?

  35. Hmmmm
    Just being a Simple Red Neck, I am easily puzzled.
    If you have one set of temperature records taken in old growth forests (I.e. tree ring proxies).
    And a second set of temperatures taken in areas that have, over the years, become Urban Heat Islands.
    And you then compare them.
    Why in the world would you expect them to match?
    Befuddled in Texas,
    Steamboat Jack (Jon Jewett’s evil twin)

  36. So let’s start with the hypothesis that trees are really better thermometers than thermometers. Now someone has to explain the following to me:
    My mother has 2 red maple trees in her yard. They were the same size when they were purchased at the same nursery and planted 20 feet apart about 10 years ago. Today one is twice the diameter of the other and the larger one is nearly 3 times as tall.
    Which one is the better thermometer? Why?
    PS The real reason one is bigger than the other is because the biggest one was planted where the old outhouse used to be, and the smallest one wasn’t.

  37. It is my understanding with wide enough error bars anything can be a thermometer.

  38. Trees like CO2 rather a lot.
    I thought trees responded rather well to increased levels of CO2, that should mean that trees should show greater growth since 1960 not less, OR DO THEY.
    http://en.mercopress.com/2010/02/08/climate-change-and-higher-levels-of-c02-making-trees-grow-faster
    The Parker and McMahon’s paper focuses on the drivers of the accelerated tree growth. The chief culprit appears to be climate change, more specifically, the rising levels of atmospheric CO2, higher temperatures and longer growing seasons.
    During the past 22 years CO2 levels at SERC have risen 12%, the mean temperature has increased by nearly three-tenths of a degree and the growing season has lengthened by 7.8 days. The trees now have more CO2 and an extra week to put on weight. Parker and McMahon suggest that a combination of these three factors has caused the forest’s accelerated biomass gain.

  39. From an earlier article:
    “Ultimately, any alternative explanation must fit all the observations. If the alternative hypothesis fails even only one of the observations, then the alternative is rejected.” Ferdinand Engelbeen
    Ok, tree rings as a temperature proxy, rejected.
    Gerry

  40. tree rings for Age of the tree, fine.
    for wet or dry seasons, fine.
    for fires, fine,
    for bugs, fungi,pollen, soil type and nutrition of soils, fine
    for the immediate surrounding area only, fine
    for temp?
    no way!

  41. What do you think would be more consistent over the centuries?
    1. Trees in forests
    2. Thermometers in villages and at airports
    The NY Times blindly accepts that #2 is more accurate gauge of temperature. Most objective observers would consider the possibility that the thermometers were measuring increased heat produced by human development.

  42. trees do not grow at -40C
    trees do not grow at +100C
    trees grow very well at 15C
    This cap shape must have a dependence on temperature. It may not be linear but it must be there.
    Somewhere between 15C and 100C the growth must start declining Did trees pass the optimum in the 60s?
    Uncontrolled emissions in the 60s, 70s and 80s was known to cause acid rain (to an extent that some countries were forced to add lime to lakes to prevent damage) there was plenty of evidence that trees were being damage also.
    Is it not true to say Damaged trees=slow growth
    There are many factors that can slow tree growth but apart from over temperature these effects will be diminished by limited industrialisation (before 1900?).
    Trees are rubbish thermometers, but in all the noise there MUST be a temperature signal. A large local sample will lower the noise from sickness, or damage. A large global sample will lower the noise from changes in soil fertility, etc.
    Nothing will remove the noise from CO2 fertilisation, or other global events.
    Some trees growing at the limit of their water needs may be negatively affected by rises in temperatures from their minimum growing value – growing in heat requires more water. these will always show a negative growth increase with temp. But if averaged with enough positive responders then these will be insignificant.
    But the signal that remains must, when averaged contain a temperature signal (not necessarily linear)
    wiki:
    “Overall, the Program’s cap and trade program has been successful in achieving its goals. Since the 1990s, SO2 emissions have dropped 40%, and according to the Pacific Research Institute, acid rain levels have dropped 65% since 1976.[16][17] However, this was significantly less successful than conventional regulation in the European Union, which saw a decrease of over 70% in SO2 emissions during the same time period.[18]
    In 2007, total SO2 emissions were 8.9 million tons, achieving the program’s long term goal ahead of the 2010 statutory deadline.[19]
    The EPA estimates that by 2010, the overall costs of complying with the program for businesses and consumers will be $1 billion to $2 billion a year, only one fourth of what was originally predicted.[16]”
    “However, the issue of acid rain first came to the attention of the international community in the late 1960s, having been identified in certain areas of southern Scandinavia, where it was damaging forests. The matter quickly became an international issue when it was discovered that the acid deposits in these areas were a result of heavy pollution in the UK and other parts of northern Europe.
    http://www.politics.co.uk/briefings-guides/issue-briefs/environment-and-rural-affairs/acid-rain-$366677.htm
    Acid rain and air pollution emerged from the industrial boom of the early 1900s onwards and the increasing levels of chemical production associated with these processes. The building of taller industrial chimneys from the 1960s onwards was largely held to be responsible for pollutants generated in the UK blowing as far as Scandinavia. “

  43. Ian W says:
    August 22, 2010 at 5:04 am
    Medical science seems to be infected with similar problems (“Meta studies” for one). Take multiple studies with different parameters and small sample size and mash them together to get a result that is less than statistically significant, then publish that x is a cancer causing agent. Take mice/bacteria that have been bred to be cancer prone smear them with megadoses of a substance and pronounce the substance cancer causing when, surprise, you find cancer.

  44. Makes sense to me, you definately have to show how, when and where all your measurements are made or else its useless. And your instruments calibration should be traceable to a certified procedure and standard.

  45. Sam the Skeptic says:
    “I’m well kitted-up in a kevlar suit and tin helmet before I say this but ….
    Is there any mileage in the hypothesis that tree rings may well be a lousy proxy for temperatures but that they could be a fair proxy for climatic conditions in general?
    Most people, certainly on the sceptical side of the argument, appear to believe that there is more to climate change than temperatures alone. If there is a “divergence” around 1960, why would that be? And would it tell us anything important about the current state of the planet?”
    I would say that, yes, in general tree rings are probably a fair proxy for climatic conditions — for the suitability of the climate or that particular tree species. Unfortunately, trees have adapted and specialized over time. There are conifers which do best in cold climates, deciduous trees which do best in temperate, relatively damp climates, other species which do well in hot arid climates.
    What is good for one species, may well be terrible for another.
    It may be possible to look at species distributions and growth rates and make some generalized assessment of climate changes based upon that. So tree rings would be just one component in this evaluation.
    That isn’t what they did. By a long way.

  46. I find it absolutely amazing that people are still arguing about tree ring records of temperature as if they were the only measure of climate change. We can compare the validity of tree ring records not only with modern temperature measurements but also with a host of other temperature proxies. Fluctuations of glaciers and ice core isotope measurements are far better and a long list of other temperature proxies can also be used. So why this fixation on one tree-ring record? There are at least 3,000 scientific publications in the literature confirming the Medieval Warm Period and the Little Ice–can one tree ring record, flawed as it is, trump all of those? I think not! This very fact alone ought to be enough to show that Mann’s hockey stick is a joke. Even if it had been produced by ligitimate scientific methods, all it would show is that tree rings are not very good recorders of climate change because it is contrary to so much other, more accurate data. Let’s get over this tree ring nonsense and start using proxies that are much better.

  47. Paul Coppin says:
    August 22, 2010 at 4:15 am s
    As a biologist, I will say for the umpteenth time, individual trees in the wild cannot be used for temperature proxies.
    Right on Paul! As a Biologist I totally concur! It is a pleasure to be here, reading the comments of everyone who are not ‘elitist scientists’ who KNOW all the answers and have ‘drunk the cool-ade’ .
    All the comments here so far are logical, and pervasive. Screw Trees as a proxy!
    I was in the Cascades several years ago with a forrester working for a lumber company, collecting spruce branches for Christmas tree wreaths which he did as a ‘sideline’. He pointed out 12 Microclimates on one mountain ridge. We collected our boughs from a species which preferred high humidity and gathed from an area shrouded in fog almost all day. Move 1000 yards and the fog and that species disappeared!
    Screw trees as a proxy! It doesn’t take Paul or I to see this logical point, as others have pointed out here!
    Thanks Anthony for this wonderful forum, and asking questions with boldness!
    The problem is that we scientists are dealing with Political Science which does not deal in logic and is not a science. Political Science deals in $ and Votes. Currently it is purchased by elitists!
    Eric

  48. I imagine it wouldn’t be hard to find thermometer to test the divergence, any thermometer should read OK as long as its inside GISS’s 1200Km radius. 🙂
    I concur with some other posters that if the tree ring proxy doesn’t agree with the thermometers after 1960 then the proxy cannot be used for temperatures before 1960 until the cause of the divergence is known. That’s just good science.

  49. What tree rings DO show is a robust character to temperature changes, taking advantage when conditions are good, and closing in when conditions are not.
    Many multiple specie tree stands develop robust responses to stress, which is why attempts to put out all fires, planting single species forests, and bug spraying may harm that very ability.
    I am reminded of the lessons learned at Yellow Stone. While attempts were underway to stem the fires, they raged unopposed. When the fires were contained and eventually put out, all kinds of things were learned about how the forest and fire relationship turned out to be beneficial.
    So the behavior of flora and fauna to stress and good times is a measure of the flora and fauna’s natural internal resources to survive, not the conditions surrounding it. And maybe that is the most important lesson to learn. The relatively mild stress of positive temperature changes, and the weather pattern variations that come with that (IF they do), will be rather easily handled by this Earth.

  50. Why look at the trees being the problem, couldn’t it be the thermometers’ fault?

    This quote is interesting. How does the divergence problem stand up against satellite temperature, rather than surface temperature? I assume the former does not exhibit some of the “adjustment” problems the latter suffers from.

  51. Paul Coppin’s post on the whole subject of the futility of using tree rings for temperature proxies is right on the mark.
    In a previous comment from a forester on the subject from another post some months ago it was stated that young trees in a forest grow very slowly due to lack of sunlight until older trees around them either die or are felled by storms, then they grow like crazy. Therefore not only must you have a significantly statistical sample of trees from a given forest, you must also have a significantly statistical sample of site conditions from that forest which include the history of neighboring trees, position in the forest, etc. It would take a knowledgeable forester teamed with an expert statistician to make such a study of a given forest. Even then you would only understand the history of the local region the forest was in.
    Are there any published papers from biologists (or foresters, for that matter) that prove that? If not, for the sake of our future, some responsible forest knowledgeable biologist should do so and then get that information to the public in some manner before we legislate our way to oblivion.

  52. If tree ring proxys from 1960 on give lower temperatures than thermometer readings it is clear that the cause of those low readings is not temperature variation. Since an unknown agent is now revealed to be present in proxy temperature measurements and since we do not know what it is all proxy measurements become suspect and should be discarded until this unknown agent is discovered and its role explained. But this is not what they did. They had a massive dataset, part of which they did not like, so they simply threw out the offending data. In science you are not allowed to arbitrarily throw out data and then substitute other data that you do like but this is what they did. It so happens that the temperature data they added included two decades of the “late twentieth century warming” which I have proven to be falsified and non-existent. The correct response would have been to declare all conclusions drawn from that collection of proxys invalid, including the entire hockey stick project. It is based upon a hypothesis that tree rings can tell temperature that has been proven to be false from their own data. To suppress key data that proves your hypothesis wrong is known as scientific fraud and they should have been brought up on charges of fraud instead of being officially whitewashed. That same gang did not hesitate to accuse Bjorn Lomborg of scientific fraud when they did not like his book “Skeptical Environmentalist.” Lomborg did not even deny warming, just urged moderation and common sense in dealing with it.

  53. The most recent climate science work has focused on paleoclimatic archeological investigations in colonial plantations. It turns out that the divergence problem can be eliminated, vindicating the hockey stick, by reading tea leaves.

  54. Divergence.
    I liked the pic and title in the post alluding to Robert Frost’s poem:

    Two roads diverged in a wood, and I—
    I took the one less traveled by,
    And that has made all the difference.

    John

  55. ” Mike McMillan says:
    August 21, 2010 at 10:44 pm
    I fail to understand the great faith in tree rings as temperature proxies. Trees do better in warm years than in cool years. Trees do better in wet years than dry years”
    Do they? There is a relationship between longevity and fecundity in most species. You can invest in yourself (longevity) or invest in offspring (fecundity). The growth of a tree, in the form of a tree ring, is an investment in self; big trees have a bigger canopy absorb more sunlight and can have more progenitor sites.
    Allow me to anthropomorphize; I am a tree, I have a ‘memory’ of the last few years weather conditions (information storage is trivial biologically), this year I can make a choice in spending my energy budget between longevity and fecundity.
    My first priority is to survive until next year, so a minimum 30% goes on housekeeping (tree rings), now my decision to produce seeds will be based on my history and memory of the previous seasons.
    If the last few years have offered ‘ideal’ conditions for my seeds to have a chance, it would make sense that I would increase my allocation of resources towards fecundity and away from longevity. In bad years, the investment decision is reversed; cut down on investment in fruiting bodies and concentrate on making myself a bigger canopy and root system.
    So the distribution of tree ring widths should not be ‘normal’, but be the same size or thinner in ‘good years’ compared with ‘moderate years’.
    I have seen no evidence that temperature, one of the least important viable for plant growth, should track growth.

  56. One would probably see the relationship between temperature and tree ring data much better if, instead of average temperature to tree ring anomaly, one compared (max-min) + precipitation to tree ring anomaly.
    Just because Mann installed the basement stairs in the attic doesn’t mean that basement stairs are useless.

  57. @ Anna V
    Proper thermometers are not calibrated against ice and boiling water. They are calibrated against reference thermometers which are in turn calibrated against more accurate themometers in a chain of traceabilty back to a Reference Standard based on the triple point of water being exactly 273.16 kelvin. (This defininition is due to change next year with the kelvin being defined in terms of the Stefan-Boltzman equation).
    Having said that, i agree, all temperature measuring devices, be they mercury in glass thermometers, thermocouples, pyrometers or even tree rings have a working range and must stay in agreement with the reference within that range. It is obvious that at current tempertures the trees used in MBH98 etc are outside their working range and that if such temperatures occured in the past then it is higly likely that they did not record such tempertures correctly.

  58. Another problem mentioned. From 1960 on, CO2 concentrations have been steadily increasing (at an alarming and unprededented rated – sorry, couldn’t resist!) providing trees more of the basic ingredient they require for photosynthesis and growth. Yet they demonstrate reduced growth rates which have been interpreted as cooling temperatures. With higher temperatures and more CO2 in the atmosphere, trees should be indicating faster rising temperatures than thermometer, not declining temperatures. If they have been so far wrong since 1960 to the present, why should we have any confidence in tree ring data as a temperature proxy prior to thermometer records? Who knows how many other times the teee ring data diverged from temperature for the same reason, yet unknown, as they have since 1960. This whole approach to temperature reconstruction should be taken with a grain of salt, it is dubious at best!
    Bill Yarber

  59. Ref – Gerry says:
    August 22, 2010 at 6:08 am
    “From an earlier article: “Ultimately, any alternative explanation must fit all the observations. If the alternative hypothesis fails even only one of the observations, then the alternative is rejected.” (Ferdinand Engelbeen) Ok, tree rings as a temperature proxy, rejected.”
    ___________________________
    How about tree rings as a climate proxy? Here’s what I was thinking: Ya take the diameter of the tree and divide by the total number of rings and this gives ya the average growth per year, then ya go looking for rings that are bigger than average and ya count them as good years. Of course, the rings that don’t come up to average they’s the bad years. Now we all know that good years are nice and bad years ain’t. That’d work, right?

  60. So basically, the priciple of uniformitarianism would say that if tree rings cannot tell temperature in the present, then they couldn’t tell it in the past.

  61. “Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries. If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.” And tree rings were used to construct the hockey stick. Apparently these people believed that if you don’t like some of the data you collected you can throw it out and substitute other data that you do like. That was the trick to “hide the decline.” I have news for you guys: if you are a scientist you are not allowed to do this. If that part of your dataset which you can independently evaluate is defective for unknown reasons there is absolutely no way to know if those parts of your dataset that cannot be independently evaluated are free of this defect. The entire dataset is made worthless because of this and conclusions drawn from it, such as the existence of a hockey stick, must be abandoned. But this is not what we see. Instead of discarding the dataset the offending data are thrown out and data that conforms to their prejudicial judgment is grafted onto it. And it is that data graft that supplies the high point of the hockey stick we are shown. Quite a trick indeed, needed to hide the decline from proxies. It so happens that a twenty year stretch of that data graft includes the so-called “late twentieth century warming” which I have proven to be fake and which is non-existent. Throwing out undesirable data and importing data that conforms to your prejudice is called scientific fraud. They should have brought him up on charges of scientific fraud instead of whitewashing him. Perhaps another group can institute that charge that the officials chose to ignore. When Bjorn Lomborg came out with his book “Skeptical Environmentalist” the warmist clicque immediately accused him of fraud to a Danish committee against scientific fraud. And he did not even deny warming, just urged moderation and common sense in dealing with it.

  62. My comments are disappearing into a black hole. What is going on?
    [Reply: for some reason WordPress was putting them in the Spam folder. Rescued & posted now. ~dbs, mod.]

  63. @Paul Coppin
    Sometimes tree rings correlate very well with recorded temperatures over a long time period.
    If you reconstruct temperatures you need many different proxies, and also tree rings.
    I believe that the MWP was as warm as the actual warm period in Europe. And I don’t understand why there is no progress in tree ring – climate science.
    But you MUST also use tree rings for climate reconstructions.

  64. So, determining a single variable within a multi-variable situation when you have no idea how to weight the other variables, much less the first clue about their values, differs from spilling the guts of a chicken to determine what the next fashion trend on the runways of Milan and Paris how, exactly?
    Please use small words. I’m a bit slow, and obviously unimaginative enough to grasp the nuance of the truths I’m to be enlightened with.
    And is it just me, but why wasn’t this a much better indicator that Mann is a garden variety snake oil charlatan than any dissection of deviously written crappy computer code to a lot of other folks, as well?

  65. Buntgen et al. 2008 uses trees that dont diverge until 2003 (follow warming extremely well) so I think you should point out that trees are responding differently in different places.

  66. Let’s hope veggie gardens in Central Oregon have traditional plants rated for its tough climate zone instead of the “Earth is warming” brands. Further more, this pressure system sets itself up for dry, dry, drought conditions (warm and dry during the day, falling to cold and dry at night), demonstrating that cold trends are what brings drought, not hot trends. For those gardeners who have little knowledge of history, their gardens filled with cantaloupe and grapes along with other warming Earth types of fruits and veggies, will be in for a rude awakening.
    URGENT – WEATHER MESSAGE
    NATIONAL WEATHER SERVICE MEDFORD OR
    229 AM PDT SUN AUG 22 2010
    …FROST EXPECTED MONDAY MORNING…
    .A COLD UPPER LEVEL TROUGH IS EXPECTED TO LEAVE DRY AIR AND
    MOSTLY CLEAR SKIES IN ITS WAKE SUNDAY NIGHT. BY EARLY MONDAY
    MORNING TEMPERATURES ARE EXPECTED TO FALL LOW ENOUGH FOR AREAS OF
    FROST TO FORM.
    ORZ030-222300-
    /O.UPG.KMFR.FZ.A.0007.100823T0900Z-100823T1500Z/
    /O.NEW.KMFR.FR.Y.0019.100823T0900Z-100823T1600Z/
    NORTHERN AND EASTERN KLAMATH COUNTY AND WESTERN LAKE COUNTY-
    INCLUDING THE CITIES OF…BEATTY…BLY…CHEMULT…CRESCENT…
    GILCHRIST…SPRAGUE RIVER
    229 AM PDT SUN AUG 22 2010
    …FROST ADVISORY IN EFFECT FROM 2 AM TO 9 AM PDT MONDAY…
    THE NATIONAL WEATHER SERVICE IN MEDFORD HAS ISSUED A FROST
    ADVISORY…WHICH IS IN EFFECT FROM 2 AM TO 9 AM PDT MONDAY. THE
    FREEZE WATCH IS NO LONGER IN EFFECT.
    * TEMPERATURE: TEMPERATURES WILL FALL TO BETWEEN 32 AND 36 DEGREES
    FAHRENHEIT FOR 3 HOURS OR MORE AT MOST LOCATIONS. A FEW ISOLATED
    AREAS…PARTICULARLY IN AND AROUND CHEMULT AND NEAR AND AROUND
    CHILOQUIN…WILL EXPERIENCE LOCALIZED FREEZING CONDITIONS AS
    TEMPERATURES FALL INTO THE UPPER 20S TO LOWER 30S.
    * IMPACTS: AREAS OF FROST WILL FORM EARLY MONDAY MORNING.
    VEGETATION SENSITIVE TO COLD TEMPERATURES AND FROST IS LIKELY
    TO BE DAMAGED OR KILLED.
    PRECAUTIONARY/PREPAREDNESS ACTIONS…
    A FROST ADVISORY MEANS THAT FROST IS EXPECTED. SENSITIVE OUTDOOR
    PLANTS MAY BE KILLED IF LEFT UNCOVERED.
    &&
    $$
    BTL

  67. The solution to the divergence problem is simple. Just rename it, call it the “dendrothermal inversion anomaly” or something. Then the problem is gone. This is fully in accord with the standards of climate science.

  68. And for the rest of us in NE Oregon, strong radiational cooling could put our gardens at risk as well. But then pressure systems that bring such cooling will NOT be tied into the global average because just the data is all that matters, not the weather pattern variations responsible for the data. Trouble is, day time temps can mask what is really a cooling trend due to the clear sky condition that brings day time heat during cooling trends. Eventually the lag will catch up and La Nina will cool even day time temps.
    HAZARDOUS WEATHER OUTLOOK
    NATIONAL WEATHER SERVICE PENDLETON OR
    525 AM PDT SUN AUG 22 2010
    ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-231230-
    EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
    CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
    WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
    NORTHERN BLUE MOUNTAINS OF OREGON-
    SOUTHERN BLUE MOUNTAINS OF OREGON-
    NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
    OCHOCO-JOHN DAY HIGHLANDS-
    EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
    YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
    FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
    NORTHWEST BLUE MOUNTAINS OF WASHINGTON-
    EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
    EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
    525 AM PDT SUN AUG 22 2010
    THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
    AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.
    .DAY ONE…TODAY AND TONIGHT
    THUNDERSTORMS
    GRANDE RONDE VALLEY, WALLOWA COUNTY, SOUTHERN BLUE MOUNTAINS
    OF OREGON, OCHOCO-JOHN DAY HIGHLANDS
    AN UPPER TROUGH WILL MOVE ACROSS THE FORECAST AREA TODAY WITH SOME
    LEFT OVER INSTABILITY AND MOISTURE ALONG THE EASTERN AND SOUTHEAST
    BORDER OF THE FORECAST AREA THIS AFTERNOON. AS A RESULT THERE IS A
    SLIGHT CHANCE OF THUNDERSTORMS ALONG THAT BORDER THIS AFTERNOON AND
    EARLY EVENING. ELSEWHERE BREEZY TO WINDY CONDITIONS WITH COOLER
    TEMPERATURES ARE EXPECTED. THE WINDS WILL DIMINISH TONIGHT WITH VERY
    STRONG RADIATIONAL COOLING WITH POSSIBLY A FEW RECORD LOW
    TEMPERATURES OVERNIGHT.
    .DAYS TWO THROUGH SEVEN…MONDAY THROUGH SATURDAY
    THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.
    HIGH PRESSURE WILL RETURN TO THE AREA WITH A WARMING AND DRYING
    TREND THAT WILL CONTINUE THROUGH WEDNESDAY. ANOTHER PACIFIC WEATHER
    SYSTEM WILL THEN MOVE INTO THE REGION BEGINNING THURSDAY WITH
    ANOTHER COOLING TREND AND INCREASING WINDS ACROSS THE AREA FOR THE
    LATTER PART OF THE COMING WEEK.
    .SPOTTER INFORMATION STATEMENT…
    SPOTTER ACTIVATION MAY BE REQUIRED.
    WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
    CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
    GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
    ARE DISPLAYED ON THE WORLD WIDE WEB AT:
    http://WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML
    ALL LETTERS IN THE ABOVE URL ARE LOWER CASE.
    $$

  69. Maybe tree rings are a poor thermometer
    OR
    On the flip side….maybe the earth where the trees were located was actually cooling!
    From Mann’s view, this is not politically correct, but it is a possibility along with the “trees are poor thermometers” explanation.

  70. Yes, dubious conclusions based on slim pickings. In summer months, in the forested NW, we leave the city, drive into the rural roads through the forests and see the temperature immediately drop 5 to even 12 degrees from what it is as we drove by the airport (where the official temp is recorded).
    Trees, along with other botanicals, are chemistry driven; affected by temperature, nutrition, water,CO2 concentration, etc. To discard tree rings based on a mismatch from 1960 forward is silly. Look at the 1000 year old trees in old growth areas on the west coast. Easy to line up the periods of favorable climate to trees, but do they indicated just temperature? Consider that temperature has a significant impact on growth; slow in winter, fast in spring and early summer.
    I do not take much heart in ground based thermometer readings parked in cities and airports. The highs and lows could exist for only a moment as the top of the hour temp is recorded. Consider frost forming close to the ground when the ambient temperatures are well above freezing. That alone is a hint that using data from a common micro climate is bad science. An inclusion of broad sources of micro climate samples would seem to improve the science of global climate, rather than the exclusive approach of current sampling.
    In conclusion, the more data from a variety of sources, the better the science. How about that?

  71. Could you please put a byline at the top of the post (or more precisely, where Dr. Pielke’s commentary starts)? Just to make the author perfectly clear.
    Thanks.
    [byline added per request. ~dbs]

  72. Occam’s Razor, when applied to:

    “But they were dogged by a problem: Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries. If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.”

    The simpler suggestion is that the way they are interpreting proxy data from trees is flawed, and/or that the homologous, “adjusted” surface temperature data as taken from thermometers is corrupted by their own confirmation bias.
    It is most unlikely, or indeed inconceivable, that trees have started responding to temperature differently since 1960 than they have for billions of years previously.

  73. “But they were dogged by a problem: Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries.”
    Isn’t that the litmus test for proxies? How well they match the present?
    Then trees are worthless.
    Not because their might not be some signal there, but because we don’t know how to find it, read it, and don’t have a clue what it means.
    Making it completely worthless……

  74. While we are at it, explaining how tree growth correlates with temperature (bogus), perhaps we can have some “nuclear expert” explain the O18/O16 ratio as a proxy for global temperature.
    Hum, the ONLY thing I know that changes that is the number of thunderstorms in tropical costal areas. (They enrich the O18, alledgedly by “fractional distillation”. I think the field effects and accelerator nature of lightning might be more likely the reason..) How and why these would correlate with global temperature ELUDES me completely.
    Max (30 years working in nuclear power/technology..)

  75. “But they were dogged by a problem: Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries. If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.”
    This is not a problem. You simply use Mike’s Nature trick to hide the decline. Prroblem solved.

  76. Arno Arrak says:
    August 22, 2010 at 8:33 am
    “………Apparently these people believed that if you don’t like some of the data you collected you can throw it out and substitute other data that you do like. That was the trick to “hide the decline.” I have news for you guys: if you are a scientist you are not allowed to do this.”
    Yeh, well, only if you’re a run of the mill scientist. That’s because run of the mill scientists don’t have the inherent insights to climate data like climatologists do. For evidence, I present the arguments against the M&W paper. Those guys are just statisticians and while they may be good with general numbers, there’s no way they can know all of the nuances of the magical climatological numbers. So, they’re wrong, just like the other statisticians (M&M) that take issue with the way climatologist handle their numbers.

  77. From the ‘Climategate’ emails …. an email from John Daly says it all really.

    Dear Chick & all
    > the first is Keith Briffa’s rather comprehensive treatment of getting
    > climate variations from tree rings: Annual climate variability in
    > the Holocene: “interpreting the message of ancient trees”, Quaternary
    > Science Reviews, 19 (2000) 87-105. It should deal with many of the
    > questions people raise about using them to determine temperatures.
    Take this from first principles.
    A tree only grows on land. That excludes 70% of the earth covered by
    water. A tree does no grow on ice. A tree does not grow in a desert. A
    tree does not grow on grassland-savannahs. A tree does not grow in
    alpine areas. A tree does not grow in the tundra
    We are left with perhaps 15% of the planet upon which forests
    grow/grew. That does not make any studies from tree rings global, or
    even hemispheric.
    The width and density of tree rings is dependent upon the following
    variables which cannot be reliably separated from each other.
    sunlight – if the sun varies, the ring will vary. But not at night of
    course.
    cloudiness – more clouds, less sun, less ring.
    pests/disease – a caterpillar or locust plague will reduce
    photosynthesis
    access to sunlight – competition within a forest can disadvantage or
    advantage some trees.
    moisture/rainfall – a key variable. Trees do not prosper in a drought
    even if there’s a heat wave.
    snow packing in spring around the base of the trees retards growth
    temperature – finally!
    The tree ring is a composite of all these variables, not merely of
    temperature. Therefore on the 15% of the planet covered by trees, their
    rings do not and cannot accurately record temperature in isolation from
    the other environmental variables.
    In my article on Greening Earth Society on the Hockey Stick, I point to
    other evidence which contradicts Mann’s theory. The Idso’s have produced
    more of that evidence, and a new article on Greening Earth has
    `unearthed’ even more.
    Mann’s theory simply does not stack up. But that was not the key issue.
    Anyone can put up a dud theory from time to time. What is at issue is
    the uncritical zeal with which the industry siezed on the theory before
    its scientific value had been properly tested. In one go, they tossed
    aside dozens of studies which confirmed the existence of the MWE and LIA
    as global events, and all on the basis of tree rings – a proxy which has
    all the deficiencies I have stated above.
    The worst thing I can say about any paper such as his is that it is `bad
    science’. Legal restraint prevents me going further. But in his case,
    only those restraints prevent me going *much* further.
    Cheers
    John Daly

  78. I planted an Ash tree for a friend yesterday. Her Maple tree died, as most do in this part of the world. She was convinced it is due to global warming.
    The guy at the nursery who sold us the tree says that Maple trees have always done poorly here, and that it is not a wise choice to plant them.
    People attribute everything to CO2, because they have been brainwashed to do so.

  79. Wow! I sense a really great cartoon here!
    Imagine: Dr. Mann is standing in the middle of a forest, jumping up and down like two-year-old having a temper tantrum, shaking his fists at the trees and wailing “You’re not cooperating!!”
    And of course the trees will have their hands (branches” on the hips (trunk), or crossed like crossed arms, and are giving him a roll-eyed look.
    Oh hey, and here’s another suggestion: One of the trees —facing away from him— has a branch (hand) down and extended in his direction, and with the caption “Talk to branch (hand)!”
    :o)
    Other than that, whenever a scientist is heard —or said— to remark that a natural process ‘isn’t cooperating’ with him, that’s tantamount not getting his way with matters.
    And isn’t that the essence of the matter, what with UHCN and GISS knocking off stations which don’t render up data with which they would agree?

  80. Did it occur to anyone that you have to find a live tree that is hundreds of years old, and any evidence of climate change would be in dead trees.

  81. for trees to be used as a proxy there needs to be some calibration done. Thats is take tree tring data and temperature data for the same timeframe and correlate tree ring to temperature …
    Then you get a factor that allows you to equate a certain size of tree ring to a temperature …
    It appears that the tree ring fools did some calibration from about 1900-1960 and then froze their calibration process.
    If they continued to use the temps from the ’60’s forwasrd then their “historical” temperatures would have had to change and they like their historical temps just the way they are … all cooked up and fraudulent …
    lets say that ring size 10 = 14 degrees based on their original calibration … from the ’60’s forward they are seeing tree rings of 8=14 degrees … (old factor would have said temp was 12 degrees) …
    If they use the new temperature data to improve their proxy calculation then the old historic temperatures would rise alot … so much so that they would look silly … thus they must throw out the data …

  82. foley hund says:
    August 22, 2010 at 9:49 am
    [–snip for brevity–]
    In conclusion, the more data from a variety of sources, the better the science. How about that?

    There is a problem with using a wide variety of indicators: Each are subject to a broad range of differing effects.
    The very nice thing about instrument data is that they afford a high degree of repeatability. That is, you may use a particular thermometer to measure temperature in many different locations, and it will perform that task admirably well provided the siting is the same in all locations.
    If you are intent upon using flora as a means of measurement, then of necessity you must resort to measuring all manner of other things in that particular local environment in order to accurately assess what else is affecting the flora.
    As has been pointed out priorly in other topics, tree growth is affected by precipitation, sunlight, the character of the earth in which they grow, their surroundings, insect predation, disease, etc.
    Since all of those things are affected by the externalities of what causes weather to happen to begin with, then it arises that measuring those things and quantifying them is all the more the better way to understand what happens down the line.

  83. In defense of tree rings, they’ve kept a great record of temperatures from the 1850’s to the 1990’s when pulped into paper sheets and used to record thermometer readings.

  84. George Turner says:
    August 22, 2010 at 12:33 pm
    In defense of tree rings, they’ve kept a great record of temperatures from the 1850′s to the 1990′s when pulped into paper sheets and used to record thermometer readings.

    Heh heh. It’s funny ’cause it’s true.

  85. “Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries”.
    ————————————————————————————–
    Anyone who finds this statement credible has left science (and reality) behind and entered wonderland…….
    Its worse than we thought….
    DFM

  86. Reading the various comments Mr. Mann would probably smile , because in reality next to nobody is asking Mr. Mann to start verifying his own theories and in a way that the particulars can be verified by the whole scientific community . Mr. Mann as far as i am aware has always used funds of the community to signal his crazy prophesies . The best thing which could happen to him is to be given the opportunity to prove himself with contemporary data visible and fully identifyable for others .
    Since he is working with funds from our society , our society is entitled to an open verification process by Mr. Mann himself . If he is really that good , he should receive the opportunity to whitewash himself and if he refuses than he should no longer be given any grants .

  87. 899 says:
    “There is a problem with using a wide variety of indicators: Each are subject to a broad range of differing effects.”
    Exactly why we use a variety. Else we put one only indicator at a location of whose choosing?
    How else do we provide for the climate millions of years in the past? Ice core has limits, rock/geological has limits, trees have limits, ocean sediments, as well as all other measures to date. When they do not agree we investigate a hypothesis of reason.
    I have to stay with more sampling is better. I enjoy my traveling thermometer; it says a lot about localized temperatures and why stationary instruments fixed at micro climates are in fact the obvious reason the tree rings do not jive with instrument data. Right? Wrong?

  88. Hi all. Please search for “D’Arrigo” and read her summary papers on “the divergence problem”. The presentation above fails to mention that it affects a small percentage of far northern tree samples only. Trees closer to the equator do not exhibit this behaviour. Prior to ~1970 the northern and southern trees are highly correlated and their match to the instrumental record prior to 1970 is strong. Many possible causes of divergence for the individual stands affected have been postulated with no definitive answer. Note that proxy reconconstructions of past temperature follow a similar patter whether or not tree ring data are included.
    Practice skepticism. Go to the source to see if this commentary is a fair reflection of the state of play.

  89. @earthdog says August 21, 2010 at 11:08 pm:
    As for changing the way they (trees) respond to temperature increases, I call upon the concept of uniformitarianism.
    Yes, this isn’t pure geology, but I believe the concept is sound.

    Very valid criticism.
    Uniformitarianism dictates that what happened in the past are the same processes and mechanisms that occur in the present, that we cannot assume different processes in the past.
    If we prove that such differences existed, then uniformitarianism is shot in the foot. It is also shot in the head.
    So, in them claiming something different for the period when instruments overlap with tree rings, they ARE saying, “Well, yeah, but you see, uniformitarianism doesn’t really apply unless we agree to LET it apply.”
    So, not only do they cherry pick their data, they cherry pick the underlying scientific principles.
    The rest of science should be all over this like flies on cow turds.
    Oh? They won’t do that? Then someone else has to. . . . Enter Steve M and Anthony W…

  90. Botanists have told climatologists that tree growth is not dependent on temperature so the use of tree rings as temperature proxies is unsound.
    Statisticians have told climatologists that their use of statistics is flawed both in methodology and sample sizes.
    Yet climatologists continue despite this expert advice to use tree ring temperature proxies and flawed statistics based on insignificant samples to support wild unvalidated claims.
    Is there any other branch of science where these behaviors would be accepted?

    ————————————————————————————-
    Paleontology-
    We can date the relative age of certain index fossils based on the ages of the rocks that contain them based on their relative location in the geologic column.
    We can date the relative age of certain rocks in the geologic column based on the ages of the index fossils they contain.
    While this is not the only way in which the ages are assigned to either rocks or fossils, and these other methods are more or less in agreement (there are notable exceptions in recent recorded history) there is more or less a consensus that the geologic column (as currently understood) to be a fairly reliable proxy to use in dating either fossils or rocks. It does not matter that at no one place on the earth do significant portions of this column exist or that at other locations the order of rock layers are out of sequence or even inverted. Such divergences are dealt with by many (sometimes complicated) theories about never observed events in the name of preserving the integrity of the idea of a geologic column as a proxy for recorded ancient history.
    I am not arguing the truth or falsity of the idea of a geologic column just pointing out a few similarities between it and the idea of a “treemometer”.

  91. I always thought that plants responded to ground temp not air temp.
    Maybe we need to bury the thermometers!!

  92. “Since the thermometers are not coincident in location with the tree ring data (in the same local area), it would not be surprising that they are different.”
    If I read this right, I would disagree with this statement. It is not the DATA itself, but the TREND in the data that is at issue.
    Using this logic, we can’t compare temps in any place with ones in any other place. But, of course, we do. Heck, we let Kola tree rings represent the whole planet, for God’s sake.
    Was this the real intent of this sentence? To say we can’t compare the tree rings to instruments? What am I missing?

  93. @ JohnH says August 22, 2010 at 1:55 am:
    Until there is a full confirmation by experiment of a Theory for the divergence the only explanation for the divergence is that trees do not react to higher temps post 1960 and never have before 1960.

    Absolutely. As earthdog says, uniformitarianism DICTATES that the overlap period GOVERNS. Therefore, all past tree ring proxies must be re-calibrated to match the overlap period – the post 1960 period. This is the only period when we can compare them. If not individual trees, then at least the overall trends.
    As per Jim Hogg — But there SHOULD be thermometers placed right AT the trees. This is such a basic scientific method! Why has it not been done?
    Dr. Pielke? On both co-locating trees and thermometers? Has it been done? And on the overlap period being the governing/calibrating period?

  94. @James Patterson –
    Briefly OT:
    THANKS for pointing out the paleontological circular reasoning. YES, so many sites around the world have inverted geologic columns, and YES, the theories are all ad hoc affairs, none of which cover all the bases.
    Archeologists do the same kind of thing. They are still wedded to the same chronology that was pegged to ceramics and paleography, the ones dreamed up long before C14 and radiometric dating. The latter truly scientific dating methods were calibrated against the less scientific methods, as I understand it all – the exact opposite of real scientific methodology would dictate.
    And, BTW, for any that don’t know it, C14 does NOT diminish linearly. That was a VERY early assumption, and one that is still the public’s understanding of it.
    End of slight OT there. Sorry…

  95. Pielke didn’t quote the best part. Gillis in NYT:

    If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.
    Most scientific papers have dealt with this problem by ending their charts in 1960 or by grafting modern thermometer measurements onto the historical reconstructions.
    In the 1999 chart, the C.R.U. researchers chose the latter course for one especially significant line on their graph. This technique was what Dr. Jones characterized as a “trick.”

    “Grafting,” not “splicing”!

  96. Rob Dawg says:
    August 21, 2010 at 10:28 pm
    Excellent snark sir. May I suggest that the supremacy of trees be vetted by an unbiased panel of Druids?
    Wow. That’s hilarious! But hey, why stop stop there?
    “Talk with a rock, a plant or a tree at least once a week. They have heard and seen everything and have much to teach you about patience, reliability and age old wisdom.” Maya Magee Sutton, Ph.D.
    http://www.dwij.org/forum/cerritomni/r3_maya.html
    rofl..!

  97. I submit that even if this proxy theory were valid in the first place, this mechanism breaks down over the years no matter what. You see, the theory is that only certain trees respond well to temperature, as opposed to other things. They do it while they are at the timberline, right on the edge, starved for basically everything else, such as water, nutrients, and sunshine. If the other factors wiggle a bit, the trees respond weakly, because they are still pretty much starved. But if the temperature goes up, the trees respond to that.
    Now here’s the problem. This theory only works as long as the trees remain right on the ragged edge for centuries, never falling off in either direction. They never get happy about anything, they never get dead, and they never get very warm. They never get much more or less water, and so on. If they ever got happy about any of the the other factors, they would start responding strongly to those factors instead.
    So the entire proxy theory requires that while the trees stay in place near the timber line (remember trees outside Middle Earth can’t move themselves), the timber line itself never, ever moves. Never. For centuries.
    How unlikely is this?

  98. Tree rings growth responds to several environmental factors, true; especially, to incident solar radiation upon the Earth’s surface (insolation). Tree rings growth width is a weak proxy to represent ancient atmospheric temperatures:
    http://www.biocab.org/Insolation_Treerings_Growth.html
    Next, a subtext from my article:
    “Notice that the width of the treerings is primarily a response to insolation rather than temperature. The reason being that Siberian Larch Trees are C3 plants, whose growth is more closely linked with insolation than it is with environmental temperature.
    It is clear that C3 plants achieve better growth when the proportion of insolation does not exceed 50% of the total insolation; for values above 50%, the growth of Siberian larch trees, which are C3 plants, is slowed progressively as solar luminosity increases.”
    Of course, as a biome evolves, its productivity decreases. The extinction of a local species means an increase in the biodiversity of bioma in the long term by competitive post-extinction replacement, in this case, of the coniferous forest. Therefore, each individual in that biome is put under higher interspecific and intraspecific competitive stress, which reduces its production. The latter also confirms that, to wide biodiversity, minor productivity in the biome.

  99. The quote of Daly says it all (thanks Ian W) and Pielke sen. makes it complete.
    There is no science close to being settled, if the tree ring technique is science at all.
    Unbelievable how this is used to cheat the whole world.
    Btw., German Prof. Schellnhuber, Chief Climate Change Advisor to chancellor Merkel in a recent interview: “One third of Hawaiian beaches are already endangered by sea level rise.” (http://www.spiegel.de/international/world/0,1518,712113,00.html)
    Any alarming signals from the Hawaiians?
    And, has Al Gore already bought beach front property there?

  100. How could any Warmist possibly respond to this scene:
    It’s mid January, we’re sitting in a ski vacation lodge, by the fire, looking out at the snow & ice covered floria… & I ask… “Why don’t we go outside & take a core & see what the winter was like here last year?!” “What was the weather like here then?”
    Are Warmist’s really that thoughtless, that uncreative, that uninquisitive? Really?

  101. If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.
    Hey, guess what started around 1960? Urban sprawl.
    So, what’s more likely, that trees suddenly stopped responding to temperature or the UHI proportion of the signal increased?

  102. Jimmy Haigh says:
    August 21, 2010 at 11:55 pm
    I was born in 1960 and I deliberately caused the divergence problem because I thought it might be fun.
    BEAUTIFUL! HAH!

  103. tree rings from 1960 forward appear to show declining temperatures
    The trees tells us temperatures are falling…
    The peer review gang tells us temperatures are rising…
    So we are probably somewhere in the middle… business as usual… natural variability.
    But if you put a gun to my head and asked me to choose between TREE and MANN then I would go with the trees… because trees don’t lie… they can only be misunderstood… which reminds me of a song from the 60s by the ANIMALS 🙂

  104. We could get a good feel for the tree ring/temp relationship by doing a serious tree ring study in the English Midlands, where we have the CET record going back to the 1600’s. Those temps are from several sources, but the study could core trees from the neighborhoods, many species, many locations. The data set could be enlarged over time, somewhat like the SurfaceStations.org data set. Other researchers could use the data for their own papers (also somewhat like SurfaceStations.org, ouch!)
    Other records might show rainfall/drought/stresses. Tax records might show crop yields as a general indication of growing conditions for a year.
    Then we could do a real PCA, and see what counts with tree rings.

  105. Should we be asking why did the trees for a short time happen to track with temperature. Is there an environmental reason or a problem with the data collection and analysis?

  106. It should be obvious that tree-ring width is primarily an indicator of the overall optimization of growing conditions in any given year. Narrow rings can be caused by conditions being too dark, too dry or too hot, as well as being too cold. Thus the use of these ring-widths to indicate average annual temperatures must be highly speculative without other independent corroborating evidence. Perhaps a detailed isotopic or chemical analysis of the material in each ring might give better results.

  107. I am now convinced that tree rings provide a better measure of temperature than thermometers.
    I hope I am there next time Mike Mann needs his temperature taken for a medical check up.
    “Bend over please sir…”

  108. Personaly I am really impressed with some scientists. Using a very small sample he has produced vast funding streams from a few wood shavings, he is pure magic!

  109. It may be that some forest ranger stations have a record of thermometer readings that could be co-related to tree-rings adjacent. These rangers would be pretty disciplined in taking down the data, but not necessarily trained in standards of thermometer siting. Yet, providing the instruments are not simply hung on the outside wall, the data might still work to compare tree-trends with thermometer trends.

  110. pps. Logging companies, too. When I went a-logging at Franklin River here in British Columbia, I had to take a thermometer reading and relative humidity calculation every morning at 10:00am, or as close to that as I could possibly get. But in this case I was there only in the summer, and the purpose of the readings was to determine if the woods were too dry for safe logging. I don’t know if the readings were continued in winter, but maybe they’ve been done elsewhere.

  111. I don’t see how you can infer temperature from tree rings. Tree rings vary with a lot of variables including rainfall, the fertility of the soil, the amount of sunlight (numbers of cludy days) and the amount of carbon available to soak up.

  112. Derryman says:
    August 22, 2010 at 8:12 am
    Thermometers, when they first appeared as an instrument, were calibrated against the triple point of water as 0C and the boiling point of water, all at 1 atmosphere. These two points set the scale which was divided by 100.
    Even on a desert island with no contact to the rest of the world one can construct a thermometer compatible with the rest of the world because of this definition.
    from wikipedia:
    From 1744 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water, both at a pressure of one standard atmosphere.[citation needed] Although these defining correlations are commonly taught in schools today, by international agreement the unit “degree Celsius” and the Celsius scale are currently defined by two different points: absolute zero, and the triple point of VSMOW (specially prepared water). This definition also precisely relates the Celsius scale to the Kelvin scale, which defines the SI base unit of thermodynamic temperature (symbol: K).
    It was the need for precision in relating the Kelvin an Celsius scales that changed the definition in international standards, certainly not a precision relate to tree rings as thermometers.

  113. I regret I did’nt build my house using timber. I could have read the temperature straight of the walls!

  114. Many temp sensors are now in urban areas or on airports and there is a strange habit of cutting down trees to build houses and I haven’t seen many trees on or around the runway at Heathrow my “local” airport.

  115. I may be, from ignorance of the research literature, be asking a silly question, but I’ll ask it nonetheless.
    ‘Why is tree growth linked to annual temperature??’
    To me, there are numerous factors at play:
    1. Temperature in the growing season
    2. Sunlight.
    3. Rainfall, both amount and distribution through the growing season.
    4. Pests.
    5. Soil nutrients.
    6. Competitor plants nearby.
    This year, we conducted a little experiment with tomato plants. My mother bought 4, but only three would fit in the special tomato grow bag, so we put one in the front garden. The effects are striking: after 3 months with the same sunlight and same temperature, the one in the front garden is about 2 feet high, whilst those in the special nutrient bag are 5 foot high.
    I would also ask you to consider the effect on growth of a few hard winters, which both reduce temperatures but may also wipe out pests. Has work been done to correlate summer growth with cold winters and what results are there? Since it is clear that, in the case of some trees like apple, crop yields are best with a hard winter, a mild spring and a warm but watery summer……is that true also for main tree growth?
    I am sure that all would agree that there is a great difference between annual temperature and seasonal temperature and it might be useful to readers to hear what the position is in research circles on that issue……

  116. James Bull
    Heathrow is frequently the warmest place in the country. According to the coordinates the temperature sensor is at the end of the runway near the perimeter fences. Are you able to confirm this visually?
    tonyb

  117. I think I can get a grant into looking into mushroom growth rings , it can all be carried out in the dark, you only need 3 mushroom heads to study them” no shortage”

  118. I once had a look at Ostrov Dikson temperatures (quite close to both Yamal and the Polar Ural sites) to see if there really was any divergence. I downloaded the June-July-August temperatures from GISS for the station Ostrov Dikson and averaged with a 3-year period to remove some of the noise: http://i45.tinypic.com/2ns6jk6.jpg
    Made me think that the divergence problem is really a problem with the temperature record, not the proxies…

  119. The problem with tree ring data is that temperature is not the only thing that affects tree growth because rain and soil (mostly rain) and genetics, also affect growth. Another big problem is that tree growth is non-linear (a bell curve) and not matched to temperature. There is a “sweet spot” in temperature where growth is highest and everything less or more than that will show less growth. For example if temperature increase were infinite, tree growth would not be. Tree growth is constrained by genetics and other environmental factors. So, of course, tree growth will not follow temperature, and therefore tree rings samples are a very poor proxy for temperature. Thus Michael Mann’s “hockey stick’ is founded on unreliable data and is therefore mostly useless except to show how NOT to do science.

  120. Ryan Welch says:
    August 23, 2010 at 11:13 am
    The problem with tree ring data is that temperature is not the only thing that affects tree growth because rain and soil (mostly rain) and genetics, also affect growth.
    Ryan, I agree. Perhaps a “multi-species” approach is best when seeking to reconstruct the historical climate pattern of any region through the use of tree ring data.

  121. The “tree and thermometer divergence problem” is improperly named. It should be named the “Tree and Hansen/Jones temperature record divergence problem.” Since we have repeated estimates that up to half of the warming in the thermometer record is due to land use changes, we do not know if there is a real tree and temperature divergence.
    If we were to assume that the tree ring data is a somewhat valid measure of temperature, then we be able to use the tree ring data as a measure of how the HADCRUT and GISS temperature records diverge from real temperatures.
    I wonder which way Dr. Briffa would care to argue this idea? 🙂

  122. Quite relevant comments in general. Single trees are terrible proxies, as there are likely hundreds of variables impacting the growth. However the idea of using masses of tree samples is that local variables are averaged out. I would call this ‘cross-sampling’, which is common method in scientific signal processing, to strenghten phenomena and average noise away.
    But actually what then tends to happen with tree samples is that northern and southern extream condition areas begin to dominate that signal. This is because changes or signal is more visible there than in more stable equatorial or lower latitudes. This is exactly why Mann’s work does not have much value. Samples were selected wither by nature or the team and cross-sampling criteria does not fulfill sceintific requirements for global temperature. It is surpricing, that this type of cornerstone criteria can be supressed in science
    Tree rings are valueble source anyway, please check check some very high quality work done with Scandinavic trees, that actually leads just to opposite conclucions when compared to Mr. Mann:
    http://lustiag.pp.fi/
    Maybe most interesting
    http://lustiag.pp.fi/treerings_and_climate-part1.pdf
    pages 17 and 18
    or
    http://lustiag.pp.fi/viljavaranto_mt.pdf
    Also Mann’s team has even revearsed some sedimentation data observed and published reversed data to match it better to their model, which is actually a clear scientific fraud.

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