Improved dendroclimatology techniques may help end climatic speculation related to tree ring analysis

For all the hubub surrounding Dr. Michael Mann’s hockey stick, the MWP, and throwing out data past 1960 because it didn’t seem to calibrate against the instrumental record, here is a way to put an end to the issue. Have Mann’s, Briffa’s and others tree ring samples submitted to isotope analysis.  Given how much UEA and Penn State want to protect their research reputations, it seems to me that this would be an excellent way to settle the issue independently. Unless of course, they threw away the original samples. – Anthony

From a press release by the Arctic Institute of North America

Carbon and oxygen in tree rings can reveal past climate information

Isotope analysis provides accurate information

Stable isotope analysis of tree ring samples at the GSC-Québec Delta-Lab

OTTAWA, DECEMBER 2009 – The analysis of carbon and oxygen isotopes embedded in tree rings may shed new light on past climate events in the Mackenzie Delta region of northern Canada.

Scientists have long looked at the width of tree rings to estimate temperature levels of past years. Larger rings indicate more tree growth in a season, which translates into warmer summer temperatures. But the analysis of carbon and oxygen isotopes in tree rings can also provide accurate data on past climate events, say researchers working in northern Canada.

In a paper published in the most recent issue of the journal of Arctic, Antarctic and Alpine Research, Trevor Porter, a PhD student in Geography and Environmental Science at Carleton University, and three other authors compared temperature data collected in Inuvik, Northwest Territories (NT) since 1957 with their own analysis of isotopes found in white spruce trees in the Mackenzie Delta region of the NT. They found a strong correlation between the two data sets and temperatures.

“Isotope analysis is a good way to measure past climate change,” says Porter about the results.

Isotope analysis is not a new way to measure past air temperatures. However, the method has not been widely used because lab costs have been prohibitive, especially when compared with the examination of tree ring width. Now, however, the cost of equipment has dropped substantially making it more affordable for researchers to use this method.

Porter’s work was carried out on the northern edge of the boreal forest in the NT where trees are small but surprisingly old. “A 15 to 20 cm. tree could be a 300 to 400 year old tree,” says Porter.

This slow rate of growth actually helps researchers because smaller trees stay standing longer. Trees that fall begin to decay making data analysis difficult or impossible.

“Once they get too large, it’s difficult for trees to persist. They are susceptible to wind and ice storms. One of the reasons trees (in the North) persist so long is because they don’t grow as much,” says Porter.

Isotope analysis allows researchers to conduct their work using a smaller sample size than needed when trying to re-construct temperature records using tree ring width. Porter explains that the width of rings can vary considerably between trees even when they are growing in the same stand. This variation can complicate reconstructions of past climate.

A number of factors influence ring size, including the age of the tree and the location of the tree within the forest. Older trees tend to have smaller rings than younger trees. And trees within the same area might not all receive the same amount of light, nutrients or even water.

“Growth is controlled by many things . . . they (trees) can all end up just a little bit different,” says Porter.

Isotope signals, on the other hand, are often very similar between trees. This means researchers can gather accurate data from three or four trees instead of the 20 they might need for tree ring width analysis.

“In ring widths there will be more variability between trees. There will be similar trends, but you have larger differences that you would find between the isotopes of different trees,” says Porter.

Porter is hoping his work will lay the foundation for a model that can be used to investigate the long-term climate history of the Mackenzie Delta region. Although the temperature record for Inuvik only dates back to 1957, the dead and live tree ring record stretches to nearly 1000 years before present. That prospect excites the young researcher.

“The tree ring record goes back almost a thousand years in this area, but it’s never been used for a temperature reconstruction. This is a really exciting time to work in climate research, especially for a young student,” he says adding, “This is a hot topic.”

###

More information can be found at www.arctic.ucalgary.ca

See this press release in PDF form here

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125 thoughts on “Improved dendroclimatology techniques may help end climatic speculation related to tree ring analysis

  1. Sunspot number: 0
    Updated 03 Dec 2009
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    speed: 365.9 km/sec

  2. Brilliant! Ask for the tree samples in a formal letter and cc the press. The ClimateGate audience will be listening…

  3. Fat chance that Briffa, Mann, et al will submit their tree ring samples to such accurate scrutiny. As you surmise, the original tree ring samples may not even exist!

  4. abbeyroad69 (15:34:38) :
    “UAE” should be “UEA”. Unless the Emirates are in on climategate too . . . . 🙂
    Nice catch.
    REPLY: Typo fixed, thanks – Anthony

  5. Excellent. As I have said in other post I think Briffa and Mann are the point persons in this whole mess. Their work is central to the whole “hide the decline” “trick”. If reputable studies are found that restore the MWP and the Little Ice Age there is no unprecedented warming, no tipping point, no crisis begging for trillions in government intervention.

  6. There is a treasure trove of climate data at the Hudson’s Bay Company archives from its traders, notably Peter Fidler, and Hudson’s Bay and Northwest Company surveyor David Thompson (his journals at the Archives of Ontario have temperature, cloud cover, precip., and wind records extending, though incomplete, from 1789 to 1812 in western North America and from around 1830 to 1845 in Montreal) who traded in Manitoba, Saskatchewan and Alberta. I am not a climatologist but would records of this sort have any relevance in this debate about temperatures in northern Canada? I have transcribed most of Thompson’s from 1790 to 1812.

  7. I understand one tree cross section is being used as a unique looking coffee table at Briffa’s house.

  8. Sorry, the original wood has been sent away to make hockey sticks and mildly comic novelty chess pieces (pawns, I think).
    You forget, the science is settled…

  9. Unless of course, they threw away the original samples. – Anthony
    Key words if they were ever spoken.
    We have a picture of Mann holding one of those slices.

  10. I am going to wait for all the details before I jump on board. What isotopes? Why should they be consistent throughout history? Etc.
    Interesting concept, but I never fell in love with the O18 in the glacier approach because it depends on assumptions about the original source of the isotope that seem shaky to me.

  11. An interesting press release and I’ll read the paper carefully when I get hold of a copy. However, I urge caution on behalf of everyone. There have been many attempts to extract an unambiguous climate signal using isotopes in tree rings. Indeed, if my memory serves me well Sam Epstein and co-workers did some early work on hydrogen isotope ratios in alpha-cellulose extracted from Bristlecone pines. I’m not saying that a climate signal is not present and that there is no measurable signal in tree rings. There is. However, one must be cognizant of the physical processes that underlie this signal. The oxygen and hydrogen isotope composition of trees is determined by the water source and subsequent evapotranspiration processes in the plant. The source is local ground and soil water which in turn derives its isotope composition from precipitation. There is a strong temperature signal in the isotope composition of precipitation which may be transferred to the tree as it grows. However it is likely that this will be modified by transpiration etc. and thus we will see other factors such as humidity, drought etc. have a bearing on the isotope composition.
    Not with standing my comments I look forward to reading this paper. Readers might also like to check the results of the Millenium project. This is an EEC funded project to look at climate variability in Europe over the past 1000 years using tree rings, tree ring isotopes, lake deposits, marine archives etc. I’m not sure what results have come from this study yet. In light of the present discussion this project assumes great importance. The project leader is Danny McCarroll at Swansea and Esper is on the team too.

  12. I’d like to see a graph supporting their claim, i.e., a close coincidence between their isotope data with an instrumental temperature record for the 20th century.

  13. Sean Peake (15:45:26) :
    Relevant? Oh my, yes. The US Army nearly fell over itself setting up stations and observers to figure out the winds & climate of the US territories in the early part of the Nineteenth Century. It was certainly high on thier priorities.
    Any picture we haven’t seen of the beginning of the Dalton is better than a big fat zero or a FILNET synthesis.

  14. I personally think Deep Climate was to late. Unless some earth shattering event derails Copenhagen our nation of Canada will be forced by other nations to sign on to an agreement that will usher in an era of tyranny we have not seen since WW II. So I will finish my posts for a good while now with this very apt poem cited by Churchill on the door steps of WW II.
    Who is in charge of the clattering train?
    The axles creak and the couplings strain,
    and the pace is hot and the points are near,
    and sleep hath deadened the driver’s ear,
    and the signals flash through the night in vain,
    for death is in charge of the clattering train
    Unless Obama backs off we are doomed to a police state run by commies and greenies. But I’ll not take it lying down!

  15. re jcspe. I wouldn’t be so sceptical of high latitude ice core from Greenland and Antarctica. The temperature signal does seem to be robust, though there are some interesting issues regarding the delta 18O versus temperature gradient. i.e. the spatial 18O gradient when mapped against the spatial temperature gradient to give the d18O versus temperature relationship does appear to be different to the relationship as determined from a single site and carrying out the test by looking back through time.
    Where there are real problems with the ice core record is in high altitude, low latitude ice fields and glaciers such as studied by Thompson and co-workers. Here source region effects dominate over temperature. Moreover, it’s my contention that many of the published studies suffer from poor quality control from sampling through to analysis.

  16. A way to settle the issue? A brand new climate guessing method? Hardly.
    It needs to be proven first, withstand scrutiny and the test of time, before it can be used to ‘settle’ anything relative ot this issue.
    Chasing the results of shiny new ways of doing things (Mannian PCA, anyone?) is what got us into this mess in the first place.

  17. Splice (15:49:24) :said “However it is likely that this will be modified by transpiration etc. and thus we will see other factors such as humidity, drought etc. have a bearing on the isotope composition.”
    I don’t know the precise techniques but I assumed that relative percentages of the isotopes would give the temperature signal. If true, I would doubt transpiration, which is just the bulk flow of water, would effect the percentages at all. I would think the main issue would be how well the ground water,that supplies the transpiration stream, represents each year’s rainfall.

  18. I applaud these fine people from my home town; but I will not hold my breath. No matter how much tax I have to pay for breathing.

  19. “Isotope signals, on the other hand, are often very similar between trees. This means researchers can gather accurate data from three or four trees instead of the 20 they might need for tree ring width analysis.”
    Brilliant! We can go from “the most influential tree in the world”, to “the most influential four trees in the world.” Now that’s what I call progress!
    I’m with jcspe (15:48:42) and Splice (15:49:24) on this one: let’s make sure the methodology is sound before even semi-endorsing it.
    BTW, thanks to Anthony for drawing attention to this promising (?) proxy.

  20. Hmmm, well there are fashions in research and regardless of the merits of this approach of studying past temperatures via isotope studies of tree rings, the world may not be receptive. Indeed, it may well soon turn out that the world has had such a bellyful of temperature reconstructions of any sort based on tree rings, that it reacts with hostility to any practitioners.
    You have to time these things right and account for human nature.

  21. Im still wondering how any future analysis of any new data can truly be trusted?
    Maybe my paranoia is ramped up somewhat, but wont it just be “made” to fit the global warming hypothesis, come what may?
    How can it be avoided?

  22. I can’t help myself. The picture of all the equipment and gadgets reminded me of what a man said when we were boarding an aircraft for a flight and he looked into the cockpit. He said”, Wow,what a bunch of barometers!”

  23. Sorry, we have a binding contract with the trees that precludes us from providing samples for analysis.

  24. Bingo, it always seemed so sloppy to try and use ring width as a temperature proxy given all of the grow factors which drive them, temperature being just one of several.
    As has been said before, start over, using this method and all of the BEST available science to reconstruct the temperature record.

  25. P Walker: very stable… As I understand it, the carbon isotopes give an indication of water-use efficiency, and the oxygen and hydrogen isotopes give a fair indication of source water type & origin. This type of analysis is not entirely clean, however. For example the carbon isotopic composition can indicate water-use efficiency, but this varies with temperature, leaf-to-atmosphere vapour pressure deficit (which tends to be positively-correlated with temperature) and soil moisture availability. In a nutshell, an unstressed and well-watered C3 plant will have a relateively low, species-specific delta 13 C composition, but values increase with water stress. Often, water stress is correlated with temperature, but it doesn’t take an ecologist to figure out from the above that the relationships are imperfect. The stable oxygen and hydrogen isotope also have some issues, as eluded to above. Still, I believe the effort recommended is worthwhile, if done by people who understand how to deal with the above (and it would be). I am fairly sure that some of this has been done before… I have no idea if this has been done on these samples. Anyone?

  26. “This is a really exciting time to work in climate research, especially for a young student,” he says adding, “This is a hot topic.”
    Lots of money out there for “young students” pursuing “hot topics”!

  27. I’m planning to call my contacts at the university which granted my graduate degree and inform them that I will immediately cease all financial and volunteer support that I provide them until they announce that they will remove (or, at least, investigate the use of) graphs and charts which have now been called into question from their website. I refuse to support a university which is putting it’s scientific reputation at risk.
    I will say that it’s a risk for them to continue using such information despite the existence of investigations at Penn State and CRU.
    While I don’t think the loss of my individual support will pressure them in any way, I think some action may be taken if enough alumni did the same thing.
    I’d appreciate some feedback on this.

  28. wobble (16:35:14),
    Feedback: Most alumni associations have class lists, so you can contact other alumni. Refer them to WUWT while you’re at it.

  29. I am assuming they mean Carbon isotopes? And in what way has this new discovery been subjected to falsifying attempts? Or is this going to be another skip-over-scientific-methods fad?

  30. Whenever the isotope discussions get going on the skeptical websites, there is always a “Splice (15:49:24) (15:59:55)” commenter who throws out just enough jargon and doubt about using the isotopes that the discussion just ends.
    Then Splice dissappears.
    Yet the climate research community are using the isotope data every day.
    Zachos 2001 dO18 isotope database has been cited in the peer-reviewed literature every second day (that is not a typo) since it was published.
    Skeptical researchers have as much right to use the information from the isotope data and if Splice thinks it is being used improperly in the climate research community, then a peer-reviewed paper describing all the problems and throwing out all the data should be prepared.

  31. What we have here is another correlation/causation argument and another, more expensive, attempt to use trees as thermometers. What is the relationship between isotopes and temperature? Is there some emperically established physical rule here?

  32. Thank God Copenhagen begins 2 days and will last till the 18th. This will insure Climategate news stays at the top of blogosphere news and perhaps be covered by the corporate networks better.

  33. Pamela Gray (16:48:22) :
    … And in what way has this new discovery been subjected to falsifying attempts? Or is this going to be another skip-over-scientific-methods fad?
    Excellent question!
    “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.” Albert Einstein

  34. “Isotope analysis is not a new way to measure past air temperatures. However, the method has not been widely used because lab costs have been prohibitive”
    Heck, what’s a few hundred thousand dollars more to the well funded climate science arena.? Subpoena the logs. Get it done.

  35. I don’t like it.. yet.
    From a mesuration point of view we were already in lala land with selecting just a couple of dozen trees.. now we accept just 3-4?
    When these guys have done a few thousand calculations on many trees on maybe 100 sites, married the results to suitable temperature recording over a number of years.. then I’ll be interested.
    I don’t know beans about this proposed science, but I know trees and how they vary sometimes quite dramatically within the same species and even clones.. thats why in a 1000ha block all planted in the same year, same species, known clones, precise spacing we don’t get decent PLEs without a 2% sample, ie, actual measurement of maybe 2000-20,000 trees in gridded plots laid over the entire area depending of stems per hectare.
    Yep, we can do a Quadi (Quick and dirty) survey of a few dozen trees that’ll give us a good indication of what we’ve got, but try telling a judge that the “science is settled” or there’s a “consensus” about the tree characteristics when we could get sued for millions for getting it wrong on a forest sale.
    And thats the point.. there’s no “balls on the line” for these jokers if they get it wrong.. no being sued for millions (or trillions in the AGW game) if they get it wrong or fudge the results.
    There’s only one defense in court, and thats if you have followed a transparent process of recognised rigour that can be repeated, plus a page of disclaimers.. then you might walk away with at least one testicle and possibly only a slightly dodgy reputation.
    JC

  36. Will astrophysicists be allowed in the debate?
    “Key Excerpts: Observations of the Sun show that as for the increase in temperature, carbon dioxide is “not guilty” and as for what lies ahead in the upcoming decades, it is not catastrophic warming, but a global, and very prolonged, temperature drop. […] Over the past decade, global temperature on the Earth has not increased; global warming has ceased, and already there are signs of the future deep temperature drop. […] It follows that warming had a natural origin, the contribution of CO2 to it was insignificant, anthropogenic increase in the concentration of carbon dioxide does not serve as an explanation for it, and in the foreseeable future CO2 will not be able to cause catastrophic warming. The so-called greenhouse effect will not avert the onset of the next deep temperature drop, the 19th in the last 7500 years, which without fail follows after natural warming.”
    http://climaterealists.com/index.php?tid=27

  37. Spenc Canada,
    Obama may do what he wishes, but his power is limited. Ratification of a Copenhagen agreement would require agreement by 2/3 of the members of the Senate. The likelyhood of that is close to zero, at least for any treaty that the green left would be happy with. Remember, Bill Clinton signed the Kyoto agreement, but fell approximately 67 votes short of Senate ratification.
    What does Obama have to do with what Canada does at Copenhagen, anyway? The failure of the US to sign on to Kyoto did not prevent Canada from doing so.

  38. Forgive me, but it looks as though they are merely constructing another house of cards. Lucy Skywalker hits home the most salient point here: Replication and transparency.
    Bill Illis raises an intriguing point as well! What a tangled mess…

  39. Oh Lord, here we go again.
    BTW, have Mann and Briffa moved lately? 😉
    Now some one is saying they can spook about a one degree difference in temperature out of a tree again.

  40. Because WUWT is becoming so popular these days, please don’t mind if I contribute some OT points for the lurkers for teaching purposes.
    CO2 Contributed by Human Activity: 12 to 15ppmv / version 1

  41. Lulo (16:27:17) : Thank you . I didn’t mean to imply that the research would not be worthwhile – it could be very enlightening . But given the problems enumerated above , how reliable would the results be ? Also , I have to assume that tree samples taken before a certain time would degrade to some extent . In other words , how long ago were the earlier samples taken and how well were they preserved ?

  42. I am stunned that this sort of research has not been done before. Paleotemperature estimates are anchored on stable isotope measurements – this sounds like a terrific idea and based in sound science.

  43. Any advancement to the science of finding usefull and reliable proxies for paleoclimates is welcome. Isotope analysis is fairly robust but previously was too expensive. This recent improvement is a good thing for those interested in the science as opposed to ideology. Let the real climate chips fall where they may. Good data analyzed properly should trump polemics. We need more science entries in this science blog.

  44. The isotope data is not the same as tree-rings.
    In tree-ring width analysis, someone cores a tree 1 to 10 times and gets out a ruler and measures the ring widths. Have you ever looked at a tree cross-section? They are not symmetrical, especially all these slow growing trees like the Yamal pines and the Bristlecone Pine trees. Have you ever seen a cross-section of a Bristlecone Pine tree – only one-quarter of the tree is alive at any one time and you can not possibly obtain a temperature signal from them.
    Here is one Bristlecone Pine cross-section.
    http://www.rmtrr.org/images/Firescar.jpg
    Then someone like Mann or Briffa puts together a new processing algorithm that artificially inflates the recent widths and discounts the Medieval Warm Period numbers and “hides the decline” in the recent ring-width figures by appending the temperature record to it. ie. one big subjective analysis that is more than a little prone to observer bias.
    The d018 and carbon isotopes, however, have been scientifically calibrated to international standards on how they vary with temperature, latitude, altitude, and local conditions in most cases.
    http://en.wikipedia.org/wiki/Vienna_Standard_Mean_Ocean_Water
    They are not subjective tree-rings.
    Zachos database contains over 14,000 individual measurements which can then be averaged out reasonably well so one can be reasonably certain about any time period.
    In this case, the researchers have to prove their measurements reflect local temperatures accurately. It does not matter how wide a ring is, they just need a sample from ring 56 which is from the year 1945. Then someone has to show the same isotope-temperature correlation exists throughout the world at different latitudes, altitudes and local condition changes.
    Viola, we move from the world of Mann to the world of real science.

  45. I’m with those who are not really thrilled by this. It still involves using sampled near-surface temperatures to attempt to measure global temperature. But the atmosphere is the smallest and most variable carrier of global heat. Microclimate and micrometeorological processes make such measurements inherently very noisy and susceptible to systematic biases.
    I’d be a lot more interested in an announcement of a reliable ocean energy storage proxy, but I suppose that’s not too likely. We’ll just have to wait a few decades and see what Argosy turns up.

  46. Pamela Gray (16:05:44) :
    I am assuming they mean CO2 isotopes?
    No. They mean the carbon and oxygen isotopes of the cellulose material in the wood. The assumption is that the plant takes up the isotopes in equilibrium with the surrounding environment.

  47. OT but,; here we go again! Almost the exactly same time as last year.
    Environmental Canada:
    “There’s no indication that this cold air mass is going to move off – it’s such a large-scale system and it covers such a big portion of Western Canada . . . there’s nothing in the foreseeable future that’s going to push it off.
    “There’s no good news, whatsoever.”
    It’s been -3 to -5 here for three days already. Just going to get colder. Same large persistent mass of cold air forming up. Jet stream has gone totally kinky.

  48. They refer to the trick used to hide the decline as something trivial that covers only the tail end of the 1000+ years of climate history.
    In actuality what they are hiding is the fact that for 30% (50 years out of 160) of the period in which they have actual temperature data to compare to their proxies, including what they claim is the warmest part of that period, there is no correlation between the two.
    Why should we assume the record for the periods where there is no temperature data are any more accurate, how are we supposed to trust their claims that there are no previous warm periods that were missed like the latest one has been?

  49. Is this another attempt at doing science by press release?
    Some immediate questions not answered by the press release:
    – What is the actual physical process that maps temperature to isotope absorption?
    -What’s the method by which water-born Oxygen is distinguished from atmospheric Oxygen ( is that even possible) ?
    -What the actual frequency of the uniformity of the isotope signal within species ? What about other species within the same vicinity ?
    -Is the data available for independent review ?
    The science is not evident from the release. One assumes the paper would elaborate on those questions.
    Does anyone have access to that paper or know of a link ?


  50. Michael (16:24:41) :
    It seems some journalist with reputations to defend are beginning to do somewhat credible coverage on climate in defiance of their corporate masters wishes.

    Please; I get the impression you don’t have the slightest idea how things work in a large, vertically stacked enterprise.
    It’s as if you think things should work out as they are depicted in Super-Hero Comic books.
    .
    .

  51. No. They mean the carbon and oxygen isotopes of the cellulose material in the wood. The assumption is that the plant takes up the isotopes in equilibrium with the surrounding environment.

    Well, obviously, this is how isotope dating is done. The question I’m asking is whether or not the relative abundance of one isotope or another is strongly correlated with temperature. When I say strongly, I don’t mean in a Mannian sense, I mean strongly!

  52. Anthony,
    Do you know if Steve McIntyre would submit his bristlecone pine samples from Almagre for isotope analysis? It would be an interesting check on the stripbark issue.

  53. _Jim (18:45:22) :
    “It’s as if you think things should work out as they are depicted in Super-Hero Comic books”
    One can dream, can’t he?

  54. Ed Scott (18:19:07) :
    Rex Murphy on Climategate
    Excellent. I have only 2 small corrections to what he said. But they won’t change the essence of his talk.

  55. Ed Scott (18:35:41) :
    Climategate expert Chris Horner discusses dishonest climate scientists on Hannity
    If anyone here knows Chris Horner I have some friendly advise for him that I’d ask you to pass along, if you would: please ask him to slow down. He has a good message but it gets garbled.

  56. Non-weapons science almost to 100% died with Climategate. RIP.
    Weapons science (nuclear, and non-nuclear) is alive, and it is normally in conjunction with the scientific method, testing, hydrodynamics, computer simulation, quantum mechanics, special – and general relativity, the uncertainty principle, and in the future, if needed, with quantum fluctuations, as well.
    Say No To Climategate!!!

  57. I for one am very excited to read this paper. I am sure some of the longtime Climate Audit participants will be as well. There were some extended discussions on that site about Mackenzie River delta data years ago. The first extended discussion I remember delving into.

  58. photon without a Higgs (19:31:36)
    If anyone here knows Chris Horner I have some friendly advise for him that I’d ask you to pass along, if you would: please ask him to slow down. He has a good message but it gets garbled.
    —————————–
    I do not know Chris Horner and I did not recognize the garbled part of his message. Chris is being slowed by the good scientists at NASA by their ignoring his FOI requests for two years, which, in retrospect, is shorter than the delays in answering FOI requests made to the CRU.

  59. It is quite possible that this could be developed into a useful technique although I can also see a lot of problems over calibration etc. But it might be possible to sort all that.
    We did with radiocarbon dating after all which went from an initial plus or minus the odd thousand years, good enough for Piltdown Man of course, to, if suitable calibration samples are available, tens of years. Certainly as a student I was able to date an old wooden settle which had been in the family for centuries, it had probably been a highly ornate choir stall from a monastery which had been abolished during the dissolution, to around 900 AD plus or minus fifty years or so.
    And we could do better than that today.
    I can say with some confidence that it would certainly be far more precise than Mann style concepts which are and always were, IMHO, pure balderdash. You might as well use a set of tarot cards.
    Dendrochronology I have no problem with: but tree rings as thermometers? Really. And they sold this snake oil for vast amounts of money? Well stranger things happen at sea I suppose.
    Kindest Regards

  60. The question I’m asking is whether or not the relative abundance of one isotope or another is strongly correlated with temperature. When I say strongly, I don’t mean in a Mannian sense, I mean strongly!

    There is some discussion on the matter and in any case, the ratio of 18O:16O is dependent on where the ice/raindrop formed and fell, not what the temperature was on the ground. In other words, it can be more of a proxy for temperatures aloft but it does take more energy to vaporize water containing 18O than it does for water containing 16O to begin with.
    But it isn’t limited to only tree ring studies. The same can be done with limestone to attempt to learn the temperature when it formed.

  61. Ed Scott (20:04:45) :
    He is not always understandable. That is all I am saying. He seems to be in a hurry.

  62. photon without a Higgs (19:31:36) :
    I disagree with your assessment. Chris Horner did indeed speak fast, but he did not ramble or garble.
    He covered ALOT of material, and I think knew he had to speak fast because time was limited.
    That is hard to do that in a small sound-byte interview.
    What a bulldog.
    Give NASA Goddard Institute hell, CEI!
    Smoke those rodents out of their hiding.
    GRRRRRR.
    Chris
    Norfolk, VA, USA

  63. I hate to be a nudge but I’d like to remind folks of this post from June 08
    http://wattsupwiththat.com/2008/06/13/surprise-leaves-maintain-temperature-new-findings-may-put-dendroclimatology-as-metric-of-past-temperature-into-question/#comments
    I think this is 6 times now. I used to have a link to the original paper but it was lost a while back. I do recall that one of the points made was that the theory of isotope ratios of O in tree rings relating a record of temperature was based on the notion that tree foliage was at ambient temperature, which this paper disproved. The last time I looked for the paper I wasn’t able to locate it thru Google. I’m sure the fact that it was done by people from the University of Pennsylvania, which shares a neighborhood with another prominent educational institution, has absolutely nothing to do with that.

  64. And by all means, [back to topic….sorry about that], subject Mann/Briffa raw data to this testing.
    Sorry, Michael, but you must yield to the standards of the scientist’s own “Hippocratic Oath”, the Scientific Method….i.e. can it be falsified??
    Let’s see it!
    Chris
    Norfolk, VA, USA

  65. Correction: From my last post: Should say “Michael Mann”, so as to clarify which Michael to whom I am referring.
    Thanks.
    Chris
    Norfolk, VA, USA

  66. Jason Johnson (19:57:47) :
    I recall a Climate Audit discussion on a tree ring study in the MacKenzie Mountain. Do you have a link to CA on the MacKenzie Delta study?

  67. I found the paper at Nature. It’s still behind the paywall, but here is the abstract
    The oxygen isotope ratio (18O) of cellulose is thought to provide a record of ambient temperature and relative humidity during periods of carbon assimilation1, 2. Here we introduce a method to resolve tree-canopy leaf temperature with the use of 18O of cellulose in 39 tree species. We show a remarkably constant leaf temperature of 21.4 2.2 °C across 50° of latitude, from subtropical to boreal biomes. This means that when carbon assimilation is maximal, the physiological and morphological properties of tree branches serve to raise leaf temperature above air temperature to a much greater extent in more northern latitudes. A main assumption underlying the use of 18O to reconstruct climate history is that the temperature and relative humidity of an actively photosynthesizing leaf are the same as those of the surrounding air3, 4. Our data are contrary to that assumption and show that plant physiological ecology must be considered when reconstructing climate through isotope analysis. Furthermore, our results may explain why climate has only a modest effect on leaf economic traits5 in general
    For those who may be interested, here is the link
    http://www.nature.com/nature/journal/v454/n7203/full/nature07031.html

  68. We discussed several paleoclimate records way back in October, including some ice core oxygen isotopes.
    However, it seems that Mann hasn’t been handling many tree samples. He must just be tinkering with the numbers which others create, or he wouldn’t be repeatedly using upside down data.
    However, it has become apparent that Mann’s funding would surely have better results if directed to others who have a better understanding of the trees. Start by giving the money to someone who has tree samples, so they can get more testing done.

  69. Another potential correlation. Not the same as cause. Like the length of women’s dresses and the state of the economy. Correlation but meaningless.

  70. What we need is documented tree ring data that shows temperature is a greater driver of growth than moisture.
    Trees grow more when it is wet. More moisture does not, of necessity, require warmer temperatures.
    Without hard benchmarked data, sampled from multiple species, and from multiple biomes; — that documents tree-ring-to-moisture-to-temperature parametrics — using known and validated site specific temperature and rainfall data,
    I argue that larger tree rings only mean a wetter yaer, not necessarily a warmer one.

  71. An honest study would first determine the growth rate of species of trees in different environments. Reading through the documents, they haven’t done that. There is skeptisicm among the scientists because of the small sample area and the probable growth due to fertilizers (CO2), water and warmth. To document temps with tree rings, they would have to eliminate all those factors. They haven’t. It’s a fraud.

  72. BTW, anyone notice a Google search on ‘climategate’ doesn’t produce suggested links (again). [snip] is going on at Google?

  73. If there are no “magic trees” in these samples –i.e. if there is indeed a very close regional consistency to each and every tree by this method. . . .then they may have something.
    I’d still like to know the theoretical underpinnings for why this is felt to work. . .

  74. No theory whatsoever can ever be “proved”. Proof is for mathematics, or other logical systems.
    A “real” theory has to be falsifiable. Often, the proponents of a theory put forth examples of how their theory could be falsified.
    From Wikipedia: “Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering observable, empirical and measurable evidence subject to specific principles of reasoning.[1] A scientific method consists of the collection of data through observation and experimentation, and the formulation and testing of hypotheses.[2]
    “Although procedures vary from one field of inquiry to another, identifiable features distinguish scientific inquiry from other methodologies of knowledge. Scientific researchers propose hypotheses as explanations of phenomena, and design experimental studies to test these hypotheses. These steps must be repeatable in order to dependably predict any future results. Theories that encompass wider domains of inquiry may bind many independently-derived hypotheses together in a coherent, supportive structure. This in turn may help form new hypotheses or place groups of hypotheses into context.
    “Among other facets shared by the various fields of inquiry is the conviction that the process be objective to reduce biased interpretations of the results. Another basic expectation is to document, archive and share all data and methodology so they are available for careful scrutiny by other scientists, thereby allowing other researchers the opportunity to verify results by attempting to reproduce them. This practice, called full disclosure, also allows statistical measures of the reliability of these data to be established.”
    Pretty much as I was taught scientific method, lo those many years ago.

  75. Carbon-14 date estimation is regularly used in archaeology and in soil science to date cultural features and soils respectively. C-14 dates are commonly calibrated against dendrochronologically dated assays. One of the most important is the bristlecone pine curve from the White Mountains on the California-Nevada border. The calibration curve extends some 9,000 years. Oxgen and carbon isotope ratios are normally applied as a check against anomalous conditions. Some sources such as marine shell, C-4 and CAM cycle plants. The C-4 plants have a tendency to sequester carbon isotopes differentially leading to skewed isotopic ratios. Oxygen isotope ratios are also used as checks on the nature of the formation environment. I imagine that a little cross-discipline collaboration could acquire much of the necessary data easily.

  76. Gregg E. (21:59:38) :
    The study demonstrated that contrary to the necessary assumption that foliage be at ambient temperature for the O isotope ratio to work, the foliage actually acted to maintain itself in a much narrower range, thereby contradicting the possibility of using isotope studies of tree rings for temperature proxies.

  77. Bill Illis, I didn’t disappear. I went to bed. You mustn’t conflate the Zachos study with the tree ring isotopes. Yes they are both measuring the isotope composition of things but the controlling factors on the isotope composition of these things are different.
    Let’s take the Zachos study first. This study reports the isotope composition of the calcium carbonate excreted by marine foraminifera. The isotope composition of the calcium carbonate has two signals: i) temperature and ii) the isotopic composition of the ocean water. The dominant signal is the isotopic com[osition of the source water which is the oceans. At any one time the ocean is relatively well mixed in terms of isotope composition with a range of less than 1 part per thousand variation. However, over time the ocean varies in isotope composition. The dominant effect is ice volume. i.e. when forming large high latitude ice sheets water that is depleted in 18O is locked up as ice. This ice, which is sourced from the oceans, mean that the oceans become enriched in 18O. It is bevcause of this we see the pulse of the ice ages.
    It is difficult to disentangle the temperature signal.
    For tree rings you measure oxygen, hydrogen and carbon isotope compositions. The oxygen and hydrogen isotopes are sourced from groundwater and the carbon from atmospheric CO2. Thus my statement that the oxygen and hydrogen isotopes are controlled by source water. However, during photosynthesis there is diffusion through the stomata. Diffusion leads to an isotopic separation and a change in the isotope composition of the water. This process is affected by physiological factors such as stomatal density which in turn responds to water availability. Hence my concern that the signal in tree rings will not be readily decoded in terms of temperature.
    Measuring the isotope composition of tree rings using automated mass spectrometry systems has been possible for over a decade now. There are a large number of studies of isotopes in tree riings, including many that have a strong plant physiology basis. Few have shown a strong and unambiguous temperature signal. Dave Wendt’s citing of the Nature article shows the problems.
    I agree that we need a way to determine proxy temperatures. That method needs to depend on a process that has a strong thermodynamic connection to temperature and our bewst option is using stable isotopes. However, I hope my discussion above shows that the problems are many when dealing with multi-phase systems (water-tree rings, or water-carbonates). Work is progressing on a new isotope thermometer that is referred to as ‘clumped’ isotope thermometry. This relies on measuring the ordering of 13C and 18O isotopes in the carbonate lattice and is very promising. But precision is as yet about +/- 1 to 2 degrees C and the measurement is technically difficult and expensive.

  78. Geo makes a very good point about ‘magic’ trees.
    I’m writing as a palaeoclimate scientist who has published over 60 papers in this area. There is a tendency in palaeoclimate science to ‘pick’ those proxies which are perceived to respond to temperature. We’ve seen this to be endemic in the tree ring literature. This is not satisfactory. The bottom line is if we need to posteriori pick proxies then the method has no scientific validity and we must reject the whole sample and method.. This is because we cannot be sure that they have responded to temperature in the past as it does today. Indeed we have a beautiful example in the divergence problem. We have a calibration period and as soon as one moves beyond the calibration period we see that tree rings do not respond to temperature.
    One should note, however, that this is also the case for many other proxies. A good example is cave deposits, so called speleothems and their isotope composition. These are often picked because one responds better to temperature than others. Indeed in the same cave it is possible to find 2 or more speleothems responding differently to the presumed same set of environmental factors. One often reads of site specific studies needing to be done to understand the local control on isotope composition. This is really another from of the divergence problem, except here we have speleothems diverging from each other and the poulation is even smaller. Again if a spleothem responds to temperature nowadays there is no guarantee it will in the past. I can show you records from long lived speleothems that grew for the past 200 thousand years that show one oxygen isotope response to the last interglacial and a different one to the present interglacial. This is hardly a recipe for a well behaved thermometer.
    It is for this reason that much of palaoclimate science is what I call, arm waving and wiggle matching.
    Interestingly the one proxy that we fully understand is that of oxygen isotopes in marine foraminifera and the ice volume record. However, this is not a direct record of local temperature.
    The goal has to be to find a proxy that we fully understand in terms of physics and chemistry and spend the money to develop the right analytical methods to make robust measurements that can be used to accurately and precisely assess temperature. It must be possible to choose any sample, at random from a population, to arrive at this robust estimate of temperature. Until we do we cannot assess past temperatures with any degree of confidence.

  79. When we’re talking about tenths of a degree and varying shade/forest cover, then trees can never be used as accurate thermometers for temperature reconstructions. It’s impossible. Scientists should have some integrity and accept that instead of being blinded by fame and money.

  80. For those doubting the O18 isotope method, Andrew Lorrey used that method on New Zealand cave speleo ring analysis which firmly put the MWP and LIA back in the climate record and proved both were global climate phenomena, not just european, and tied the climate swings to long term variations in ENSO, NOT to CO2 levels. I support this method and join in demands that it be applied to Yamal’s cores.

  81. Well done young Trevor Porter. Good luck and good Science in your research.
    An outstanding example to your seniors in the field.

  82. Mike Lorrey, the Andrew Lorrey (any relation?) paper looks interesting. Yes, one often finds a good relationship between precipitation amount and the carbon isotope composition of speleothems. Similarly, one also often finds a good relationship between oxygen isotope composition and temperature and this may give good qualitative, and semi-quantitative information on temperature in the past. However I pose the following questions:
    1) Has the empirical relationship between cave temperature and oxygen isotope composition of speleothems for the New Zealand caves been determined. I haven’t had a chance to read the paper but my reading of the abstract and contents suggests that the oxygen isotope record has been compared to other proxies and not directly to temperature.
    2) How does this relationship compare with what we know of equilibrium oxygen isotope partitioning between water and carbonate? If it is different it indicates that there is disequilibrium in the system that may vary over time.
    3) Has the record been subject to testing by use of a calibration period and then a period in which the temperature is predicted and compared to actual temperatures?
    4) Are their truly independent and accurate age models for each of the proxies. Perhaps growth layer counts, tree ring chronology, U-series and 14C dating that allow cross correlation of the records? If not then we are ‘wiggle matching’.
    If not then as I’ve said in earlier posts the speleothem proxy, whilst very useful, doesn’t allow us accurately and robustly to estimate temperature.
    We must ask these questions and be very careful of not falling into the trap of ‘confirmation bias’. Just because the speleo record matches (wiggle matches?) other proxies doesn’t mean it is a true record.
    I’m not doubting the value of the Lorrey record and will read it when I can get free access tomorrow. It is another piece of the jig saw but in all probability is not able to answer positively to some, if not all, the questions I pose above.
    I hope readers don’t get me wrong. I have been, and am still an speleothem researcher but have a realistic outlook on what these archives can tell us.

  83. So Splice, since there are too many uncertainties in using the isotope data, I think the climate science community should close down all Stable Isotope Labs (like the one at the University of East Anglia) and save some money for better research that has more certainty. Maybe someone wants to write a letter to the UEA about this.
    The last times the isotopes got discussed at Climate Audit and Jeff Id’s site, a poster made the exact same points as you did in exactly the same way, using the same terminology and effectively just short-circuited the discussion. Then he disappeared never to post on any other topics. He might have thought he was being helpful or he might have thought it would be good to turn the sceptical community off using the isotope data.
    In my last PaleoClimate post, Paul Dennis of the University of East Anglia promised to write an Isotope Primer for us within a week and it is now 7 weeks later. I said I would wait on posting Part II of the series until Paul Dennis posted up his article and Paul Dennis has not posted on any other topics that I am aware of. Obviously, other events might have taken over since then but this just effectively short-circuited the discussion again.
    The sceptical community should be using this data since it is far better than tree-rings and we should also move forward on using isotope analysis from trees as proposed in this article.
    It might actually be able to prove the WMP and the LIA and the Roman Warm Period were real climate events and then the hockey sticks can be put away for good.

  84. Bill Illis, I think you are misrepresenting my views and taking an unecessarily combative position. The sceptical community should be using the best available science and some of this involves isotopes. But we have to talk from a position of authority and knowledge and that means we have to have a full understanding of these isotope systems.
    Now to your point about closing down labs. First stable isotope geochemistry is about much more than palaeotemperatures. It is about tracing sources, sinks and processes in the natural environment. Palaeotemperatures and geothermometry are but a small part of this. Ergo your statement about closing labs down is meaningless and lacks rigor.
    Now to back to stable isotopes and palaeothermometry. They are our BEST option of getting anywhere near to being able to determine past temperatures. However, my point is that interpretation is not easy and we would be foolish to think otherwise. You readily cite Zachos and tree rings together and my point was they are measuring different things and not just temperature.
    We readily criticise others for confirmation bias and it would be easy to go down that route with respect to isotopes.

  85. Michael (17:36:59) :
    Because WUWT is becoming so popular these days, please don’t mind if I contribute some OT points for the lurkers for teaching purposes.
    CO2 Contributed by Human Activity: 12 to 15ppmv / version 1
    Great Video Michael!
    That’s what’s needed. Now we need another that shows people how much temperature change these bozos are talking about/ A Tenth of A Degree, here and there, whether F or C. A diagram of the depth of the atmosphere and the corresponding temperatures as altitudes increase…

  86. ******
    Gregg E. (21:59:38) :
    We show a remarkably constant leaf temperature of 21.4 2.2 °C across 50° of latitude, from subtropical to boreal biomes.
    A main assumption underlying the use of 18O to reconstruct climate history is that the temperature and relative humidity of an actively photosynthesizing leaf are the same as those of the surrounding air

    Now wait just a minute! How can the leaf temperature be constant across this wide range of latitudes and the same as those (temperature and humidity) of the surrounding air.
    That implies that the air temperature and humidity of the air would be constant across this latitude range, which just ain’t so, as any nightly TV weather report shows.
    ******
    I’m no expert, and just going from memory, but my take on this is that leaves are evaporation “machines”, regulated by the stomata openings, and that these openings act to keep leaf temps near a fairly constant ~70F (~21C), no matter where it’s at, tropic or sub-arctic. The purpose, I’d guess, is that photosynthesis is most efficient around 70F.
    Remember, sun striking the leaves will, without this evaporation, cause them to be fairly hot, like any dry surface under the sun. So even leaves in the sub-arctic would otherwise be hotter than 70F in the sun even when air temp is lower than that.
    So this would seem to throw a monkeywrench into the oxygen or carbon-isotope method. Except that the leaves are building sugars, and cellulose for stems, branch, trunk, etc, is produced in the cambium of the stems themselves (using the sugar as fuel), and the stems supposedly are at or near ambient temps, so perhaps the method could work.

  87. Splice (04:28:07) :
    “Mike Lorrey, the Andrew Lorrey (any relation?) paper looks interesting. ”
    Yes, he is my cousin, got his BS in Geology from Boston U, MS in hydrogeology from U Maine Orino, and PhD in climatology from U of Auckland. As for your questions about the isotope science specifically, I would refer you to talk to someone like him, whose geology and climatology training combines to be most qualified to answer your questions. He’s very sharp. I recall one time after we had a ski trip to Sugarloaf, he returned to the mountain to do snow cores at the summit and did mm by mm isotope analysis of the snow, defining where the storm for every layer of snowfall originated by the isotope distribution of the dust in the snow.

  88. Gregg E
    Re your posting at 20:51 today . I saw the video of Ben Santer at Caltech ( except for the discussion) . He sums up the present science the IPPC has used to conclude AGW.
    His lecture does not really address the methods other than atmospheric data collection in detail.
    I realize there are big problems with some of the surface area temperatures re the urban heat island effect, but can you or others critique some of the other data he presents, in particular the atmospheric and oceanic data?
    Thanks

  89. I never bought the ring-width as a proxy for temperature hypothesis. Too many variables. On my small spread I find shade and precipitation to be two monster variables. The isotope idea sounds interesting, but totally out of my league.

  90. It is also well known among tree survey personnel that vastly varied growth rates can be observed in trees located only a few hundred meters distant from eachother.
    A simple visit to one of the huge tracts of pine planted for lumber and paper (all the same age chronologically) will show significant variation among trees.
    Furthermore, issues such as soil composition, depth of the water table, precipitation drainage rates, location with respect to floodplain, etc; can and do cause signficant variation within a forest (separations of kilometers).

  91. Dave Wendt (21:44:08) :
    I managed to locate a full version of the leaf temp paper I referenced above
    http://www.sas.upenn.edu/earth/pdf/nature07031.pdf

    Thanks for bringing this up again. I remember discussing it here when it first appeared.
    What it is saying actually is that trees have a way of keeping their ambient temperature constant, and actually, if there is any thermometer function in the tree ring width data, that is what it is also saying: trees give constant temperatures.
    In view of this, even measuring tree temperatures with isotopes should show this constancy ( and the so called decline, which is a decline, considering the errors, only if one expects a rise).
    Let us make a gedanken experiment: suppose one took all those nicely documented bones all over the museums, and go to graveyards that exist from the middle ages and take bone samples and measure the temperature given by the isotope ratio versus time.
    You laugh?
    Of course, because we know that humans have an internal temperature of 38.something and of course the plot over the years would be constant.
    It seems that trees have a constant temperature of 20.something in a similar manner, ie biologically controlling temperature of their growth.
    I think it is important that the measurements of the link are repeated and verified by independent experiments. That would end the trees as thermometers attempts.

  92. I can only think of margarine and eggs. Margarine was the healthy substitute for butter until trans fat was discovered. Eggs were the ‘unholy grail’ until it was discovered there was a ‘good’ cholesterol. As we learn more about climate, I feel the current hysteria may be viewed as quite silly.

  93. anna v (12:43:18) :
    It is a bit more complicated, because trees are found in many species, but that is a durned good point if a Wal-mart working, denier, beer-swilling redneck has not never seen one.

  94. “The sceptical community should be using this data since it is far better than tree-rings …”
    It’s still tree rings. Its just a different way of measuring them. All of the surface temp to biology issues still obtain, they just manifest a bit differently. The leaf temp vs air temp issue presented above is an example. Lack of temp info outside the growing season is another. Length of growing season is a related but different effect. This isnt like reading a geiger counter …

  95. I believe that isotope analysis should be a more reliable tree thermometer than gross ring width. If it works in ice-cores, why not in trees especially when bound fast in carbohydrates. I think it would be best to have all tree-samples prepared with a thorough vacuum drying process to remove all volatile contamination.

  96. I’ve now had a chance to read the Lorrey et al (2007) paper referred to above:
    Speleothem stable isotope records interpreted within a multi-proxy framework and implications for New Zealand palaeoclimate reconstruction. Quarternary International, V187, 52-75.
    I posed 4 questions above and can answer those now:
    “1) Has the empirical relationship between cave temperature and oxygen isotope composition of speleothems for the New Zealand caves been determined.”
    No. An empirical relationship between cave temperature and speleothem oxygen isotope composition has not been determined. Thus it is not possible to estimate temperatures other than by using qualitative terms such as warmer, colder etc.
    “2) How does this relationship compare with what we know of equilibrium oxygen isotope partitioning between water and carbonate? If it is different it indicates that there is disequilibrium in the system that may vary over time.”
    It’s not possible to determine if these speleothems are in isotopic equilibrium or not.
    “3) Has the record been subject to testing by use of a calibration period and then a period in which the temperature is predicted and compared to actual temperatures?”
    No
    4) Are their truly independent and accurate age models for each of the proxies. Perhaps growth layer counts, tree ring chronology, U-series and 14C dating that allow cross correlation of the records? If not then we are ‘wiggle matching’.
    Yes
    So in summary this paper does provide evidence of a mediaeval warm period, followed by a cooler, wetter period and finally a degree of modern warming.
    It is not possible to use the isotope data to estimate temperatures. Indeed the comparison with temperatures in this multi-proxy study is with temperatures estimated from tree rings.

  97. Splice (04:16:10) :
    “I’ve now had a chance to read the Lorrey et al (2007) paper referred to above:

    It is not possible to use the isotope data to estimate temperatures. Indeed the comparison with temperatures in this multi-proxy study is with temperatures estimated from tree rings.”
    I’ll note that he seems to have intentionally excluded data later than the early 19th century. I have not discussed this with him so I don’t know why he did that, or whether the speleo source had such data. I suspect, however, that if it was intentional it was done so as to get the paper published by the peerruhveewdliturchur by not directly challenging any modern claims of warming by the Team relative to the actual temperature record, which would obviously raise flags and cause the Hockey Team as evinced in the CRUtape Letters, to go into supression mode. Now the paper is part of the scientific record and helped the MWP and LIA become reestablished as being climate phenomena that existed, and did so beyond northern europe, despite Team claims to the contrary.
    Again, this is my personal speculation only.
    I suspect that there needs to be some modern standards set as to what isotope levels correlate with what temperatures, if that is possible. O18 should behave the same in response to temperature and altitude around the world, as well as to carbon levels, which is also in the record. The very fact that O18 and C14 levels vary out of synch with each other should be evidence enough that carbon levels, which are a proxy for precipitation, not temperature, do not determine temperature.

  98. Mike, I think Andrew’s paper is very good and an excellent addition to the palaeoclimate science. I hope that he didn’t feel he had to exclude modern data to get the paper published. If so then this is a terrible indictment on science in the present day.
    With regard to your last point about 18O levels and temperature. This is not an easy question to resolve. It is not the 18O concentrations in a sample per se that allows us to estimate growth temperatures of speleothems. It is the partitioning of 18O between the parent drip water and the carbonate of the speleothem. Thus to determine temperatures one needs to know the isotope composition of the drip water from which the speleothem grew and the isotope composition of the carbonate. One then needs to prove isotope equilibrium between the speleothem and the water.
    To recover the isotope composition of carbonate and its parent drip water is not an easy measurement and has only been successfully done in a handful of studies.
    I’m sure if you talk with Andrew about this he can give you the full low down on isotope thermometry and the problems inherent with speleothems. It’s a fascinating problem and one that keeps many scientists occupied full time!
    I do agree with you, and all others here that isotopes are probably our best route to temperature estimates but one needs to be aware of the limitations as well as the promise.
    There are some very exciting developments in what is called ‘clumped’ isotope thermometry and I predict that over the next 2 to 3 years a number of papers will be published showing robust temperature estimates for speleothem growth. These will have precisions of about +/- 2 degrees C. Such precisions are only really useful for studying major temperature transitions such as from glacial maximum to interglacial optimum. For studies of climate over the last millenium the precision will need to improve to be better than sub degree, and ideally on the order of 0.2 degrees. This is some way off and depends on improvements in measurement technology, either mass spectrometrically or spectroscopically. However, I do believe such improvements are possible.

  99. Obama can sign up for whatever he wants but treaties require a two thirds majority in the Senate and he will never be able to muster the votes. He’s going to backdoor compliance with the treaty by getting the EPA to issue CO2 regs that will produce the same effect.
    With CO2 defined as a pollutant, your every breathe will be regulated as well as your lawn mower, barbeque, fireplace, stove, furnace, car, boat etc. Expect the prices on all of those to go up to as the EPA imposes a carbon tax and then the money will get shipped over to Somalia to help fund ship hijacking or China to fund their replacment of our remaining industries there.

  100. “I believe that isotope analysis should be a more reliable tree thermometer than gross ring width. If it works in ice-cores, why not in trees especially when bound fast in carbohydrates.”
    Gross tree ring width is carbohydrates. The biological processes of wood production, and their inherent confounding of temp signal, are still depended upon. Ring by ring or atom by atom, it is still a tree. Rushing from one shiny new metric to another doesnt necessarily gain anything. It might, but only time and testing will tell.

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