A response from Jeff Severinghaus on why the trees don’t make good thermometers after 1950 – “I did indeed feel at the time that Mike Mann had not given me a straight answer. “

I had a brief email exchange with Professor Severinghaus about Steve McIntyre’s recent post on his discussion with Mann and others about the divergence problem. I post it without comment, with permission and without emphasizing any of his words:

Dear James,

This is fascinating.  I had no idea these emails were in the public domain.

In general Steve has gotten most of this right.  There really is a problem

with the trees not being sensitive to temperature after about 1950.  My

current best guess is that the higher CO2 since then has caused greater

warming at night (which is corroborated by minimum temperature trends,

since minimum temperatures usually occur at night).  Trees respire more

at higher temperature, so they lose carbon when nights are warmer

than average.  So their ring width has not increased as much as it would

have if the warming had been uniformly distributed over the diurnal cycle.

I think this is all published now so it should be possible to set the whole

record straight.  But I did indeed feel at the time that Mike Mann had not

given me a straight answer.  So if there is a response written, it won’t be

one defending Mike.

Jeff

Cheers,

James Padgett

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91 Responses to A response from Jeff Severinghaus on why the trees don’t make good thermometers after 1950 – “I did indeed feel at the time that Mike Mann had not given me a straight answer. “

  1. Bernie says:

    James:
    Nicely done. If Severinghaus is correct, then there is yet another major complexity in tree rings as thermometers. It sounds like there are other players to be heard from on this.

  2. James Sexton says:

    Then allow me to put emphasis where it belongs….. “But I did indeed feel at the time that Mike Mann had not given me a straight answer. So if there is a response written, it won’t be one defending Mike.”

  3. James Sexton says:

    Of course what often gets lost in these dendro discussions is the fact that temperature reconstructions using tree rings is akin to phrenology. But, even if it wasn’t, how many years did we have local temps in the areas by the trees? Not very damned many.

    Osborn:
    Because how can we be critical of Crowley for throwing out 40-years in the middle of his calibration, when we’re throwing out all post-1960 data ‘cos the MXD has a non-temperature signal in it, and also all pre-1881 or pre-1871 data ‘cos the temperature data may have a non-temperature signal in it!

    So, for an ~ 200 year history, we’re throwing out more than half of the years, because they don’t match the actual temps, but they say they match actual temps…..lol.

    The pinheads, through statistical acrobatics, found a brief window of time where the numbers almost correlated. Then drew their sticks from that.

  4. Andre says:

    Students/post docs routinely do studies on (local) living trees on a daily basis. It’s likely that they have very detailed data on correlation with meteorological data, temps, precip, humidity and what have you, upto this year. They should publish some of that.

    Obviously it is assumed that the best place to register temperature data in treerings is where temperature is considered the most limiting factor, i.e. close to the arctic or mountain treelines. However if trees react to carbon fertilization, those trends should be visible in those contemporary studies of local trees. Is there a ‘decline’, students?

  5. Simon says:

    Overriding this all though is still the assumption that trees would be a good proxy for temperature if it wasn’t the obfuscating action of increased heat from CO2.

    The recent post containing a letter from John Daly listed no fewer than 6 completely valid other factors affecting tree ring width, meaning it will NEVER be possible to separate a temperature signal from the noise. Trees should just be forgotten about and more reliable proxies found.

  6. William Abbott says:

    Severinghaus best guess is warmer nights make the tree grow more slowly? Okay – my best guess is increased atmospheric CO2 might increase the growth rings because there is lots of empirical evidence trees grow faster (ie fatter growth rings) in a CO2 enriched atmosphere.

    I know the point is: Mann was evasive. …but trees not being sensitive to temperature after 1950 is a lame excuse for stinky data.

  7. Doug Badgero says:

    The partial list of state variables that effect tree ring growth from John Daly:

    sunlight – if the sun varies, the ring will vary.
    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

    Growth will be nonlinear in all/nearly all of these variables. In fact, some of these affects would result in discontinuities rather than just a change in growth rate (e.g. pests). Even if we knew what the nature of these nonlinear responses were we could not solve this “problem” without knowledge about initial conditions for all state variables. That is, we would need knowledge about all of the variables, at sufficient resolution and accuracy, for the last 1000+ years. And we would need this information on a spatial scale that allowed us to address the individual advantaged tree. It’s absurd.

  8. Ian H says:

    With regard to the explanation that warmer temperatures at night meaning trees respire more and lose carbon …

    If false it fails as an explanation of `divergence’.

    If true it explains divergence by completely invalidating the use of tree rings as a temperature proxy. The assumption is that the response to warming is greater growth, not less.

  9. More Soylent Green! says:

    USA Today:

    Most climate scientists, more than 97% , agree that burning fossil fuels leads to global warming. Learning that makes people more likely to call for action to address a changing climate, reports a public opinion team.

    http://content.usatoday.com/communities/sciencefair/post/2011/11/public-learning-scientists-agree-on-climate-a-game-changer/1

    But it’s not true!

  10. Kurt in Switzerland says:

    WTF?
    Wouldn’t the logical conclusion be “these particular tree rings are a poor temperature proxy” if the most recent data (which one would expect to be the highest quality of the set) showed an inverse relationship?
    What incredible twisted logic on lack of nighttime cooling And its effect on tree ring growth — has anyone else postulated this, or was he imbibing in the nectar of the vine (or perhaps one bong too many)?

    Kurt in Switzerland

  11. polistra says:

    After 1950 we have thermometers. In fact, after 1750 we have steady records from a few carefully maintained thermometers. We shouldn’t even be discussing other measurements for years when we have thermometers, and we shouldn’t even be trying to average or mix temperatures in different places.

    Remember junior-high science class? The teacher puts one hand in cold water and the other hand in hot water. He says “My left hand is at 100 degrees, and my right hand is at 40 degrees. Thus my Average Hand is at 70 degrees, which is perfectly comfortable!” The more alert students understand the fallacy immediately. None of these so-called “scientists” were alert students.

  12. APACHEWHOKNOWS says:

    So, on Mann’s and the teams trees.
    Is it possible the trees are working true with “Origin of Species” as they do not know the path set for them by the team.

    Time , tide, and trees too await evolution not hockey stick graphs.

  13. Theo Goodwin says:

    Professor Severinghaus believes that there is empirical work that will withstand scrutiny and that explains “the decline” in tree rings. I cannot wait to see this. I just cannot wait. If it exists, it will be the first empirical work done by The Team.

    Anthony, why did you not post the links that the professor provided to this empirical work? /sarc

  14. TerryS says:

    > so they lose carbon when nights are warmer than average.
    This is a hypothesis that can be verified by experimentation. It wouldn’t even take that long to test it and it would make a change for dendroclimatologists to perform an actual experiment rather than playing with stats packages.

  15. James Sexton says:

    Theo Goodwin says:
    November 28, 2011 at 2:02 pm

    Professor Severinghaus believes that there is empirical work that will withstand scrutiny and that explains “the decline” in tree rings. I cannot wait to see this. I just cannot wait. If it exists, it will be the first empirical work done by The Team.

    Anthony, why did you not post the links that the professor provided to this empirical work? /sarc
    =====================================================
    It’ll probably be published just as soon as the empirical work about the missing heat at the bottom of the ocean is published.

  16. This opens up another front – one senses a rather cold front for the Team. Well done James, thanks Professor Severinghaus.

  17. RobertInAz says:

    Dr. Severinghaus points out one mechanism that might cause trees to fail as a proxy for temperature and implies there may be others.

    For me, this begs the question of what mechanisms may have invalidated the proxies used to disappear the Medieval Warming Period.

    I found the concern about warming mind boggling in the 1990s because we are inevitably heading into another ice age.

    I found the divergence problem mind boggling in the 2000s because it means the proxies cannot detect prior warming periods.

  18. Gary Pearse says:

    I know correlation is not causation but surely divergence is another matter. As a scientist, I would have taken divergence as an indication that the pre-divergence correlation is indeed not causation.

  19. TomT says:

    So the decline is CO2 fault also. CO2 is causes everything except good things. Now I ‘ve got it.

  20. John says:

    Severinghaus’s current best guess — that warmer nights mean that trees respire more CO2, hence have less carbon to add to tree rings — is quite interesting.

    But, since the Medieval Warm Period (MWP) has now been restored, including in the Kobashi et al 2009 paper of which Severinghaus was a co-author, then I would have imagined that the same effect of warmer nights and thus smaller tree rings would have been observed back then. But it doesn’t seem to be that way. Is there a reason why CO2-caused warmth increases (today) would cause nightime temps to be higher, while non-CO2 increased warmth (the MWP) would not cause nighttime temps to be as high as with CO2-induced warmth? I can’t think of a reason.

    I may be missing something, but if I’m not, then the warmer nights hypothesis for smaller growth in tree rings doesn’t seem quite right.

    The other thing is that CO2 is a fertilizer. The Idsos and many other researchers have shown time and again that plants grow more quickly with more CO2. Tropical trees and temperate trees add more carbon lately, in our now higher CO2 environment, we’ve seen in a number of studies. So if the trees add more carbon, why would tree rings show less growth? In theory, the added carbon could be more in roots than above ground, but I know of no reason why that would be, at least not yet.

  21. Matt Skaggs says:

    Cross-posted from Climate Audit:
    Excerpt from 0237, Tim Osborn, March 2006:

    “I have co-authored a paper in Nature on the reduced response to
    warming as seen in tree-ring densitometric data at high-latitude
    sites around the Northern Hemisphere, increasingly apparent in the
    last 30 years or so.
    First, it is important to note that the phenomena is complicated
    because it is not clearly identifiable as a ubiquitous problem.
    Rather it is a mix of possible regionally distinct indications, a
    possible mix of phenomena that is almost certainly in part due to the
    methodological aspects of the way tree-ring series are produced. This
    applies to my own work, but also very likely to other work.
    The implications at this stage for the ‘hockey stick’ and other
    reconstructions are not great. That is because virtually all long
    tree-ring reconstructions that contribute to the various
    reconstructions, are NOT affected by this. Most show good coherence
    with temperature at local levels in recent decades. This is not true
    for one series (based on the density data). As these are our data, I
    am able to say that initial unpublished work will show that the
    “problem” can be mitigated with the use of new, and again
    unpublished, chronology construction methods.”

    If I am interpreting this correctly, Osborn is saying that the “divergence problem” with the hockey stick arose primarily from “methodological aspects,” and had little or nothing to do with actual tree rings. I, and many others I’m sure, have suspected this ever since MM03.

  22. Phil says:

    Hold on for a second.

    Let’s accept, for the sake of argument, that when you measure the trees rings of trees situated in extreme locations, there is a high degree of correlation between the ring growth and temperature with one exception: if the temperatures are very high, as they are now, there is some, as yet not fully explained reason why the growth is lower than one might otherwise expect.

    That assumption would fully explain the current situation—temps are up but tree ring growth is modest.

    So now lets look at the dendro chronological record over the last couple thousand years to see if there are any extreme temperatures. How do we find them? Not by looking for the very highest ring growth but by looking for modest growth. And look, there are lots of examples. To be sure, most of the examples of modest growth correspond to modest temps, but we’ve just established that extreme temps are associated with modest ring growth, so we can’t look at the ring growth record and conclude there are no extremely warm temps, we just don’t know.

    The ring scientists want us to believe that record high temps are associated with record high growth, and since there is no record high growth there must be no record high temps in the past.

    Yet we’ve established, with 30 years of empirical evidence, that record high temps are associated with modest ring growth, so one cannot use the ring growth to exclude high temps in the past.

  23. CheshireRed says:

    Daft question; has anyone else tried to re-create Manns work? Perhaps not the HS 1000 years, but what about say, the 20th century? How accurate or otherwise would other tree rings be in replicating known temparatures?

  24. Here is a e-mail from FOIA that sheds some light on the subject:
    http://foia2011.org/index.php?id=647
    A letter regarding IPCC revisions, dated 9/23/99

    My main concern here is with a reference by Mann writing that Briffa’s tree ring series shows a decline, a decline in temperature, using Briffa’s tree ring series for the MBH99(hockeystick)

    Mann,
    “Clearly there is one overiding thing to make sure of here: that
    we have the right version of your series. I *think* that we do.”
    (talking about Keith’s tree ring series.)

    Later Mann writes:
    “This directory has all the series, aligned as I described to have
    a 1961-90 base climatology (or in the case of your series, a pseudo
    1961-90 base climatology achieved by actually matching the mean of your
    series and the instrumental record over the interval 1931-60 interval).”
    (The directory no longer exists, but whats inferred here Briffa’s tree ring series is pseudo?)

    Briffa replies, in regards to the robustness of the MBH99 series.
    “Mike , I agree very much with the above sentiment. My concern was motivated by the possibility of expressing an impression of more concensus than might actually exist . I suppose the earlier talk implying that we should not muddy the waters’ by including contradictory evidence worried me . IPCC is supposed to represent concensus but also areas of uncertainty in the evidence. Of course where there are good reasons for the differences in series ( such as different seasonal responses or geographic bias) it is equally important not to overstress the discrepancies or suggest contradiction where it does not exist.”

    Is Briffa here stating that ‘we’ shouldn’t include contradictory evidence in the IPCC report?
    He later says the IPCC is suppose to represent consensus.
    Basically, the ‘we’ decided what was put in the IPCC and not the IPCC reporting the findings they received.
    Essentially making the IPCC a puppet of the “The Team”

    Here it gets a little dicey. I believe the next quote was actually a copied response by Briffa on something Mann had previously written, or so it seems.

    Mann,
    “I am perfectly amenable to keeping Keith’s series in the plot, and can ask Ian Macadam (Chris?) to add it to the plot he has been preparing (nobody liked my own color/plotting conventions so I’ve given up doing this myself). The key thing is making sure the series are vertically aligned in a reasonable way. I had been using the entire 20th century, but in the case of Keith’s, we need to align the first half of the 20th century w/ the corresponding mean values of the other series, due to the late 20th century decline.”

    Taking what they like and leaving the rest.
    If they didn’t like the result, the “team’ just spliced in whatever data they wanted to produce the desired result.

    The tone I am picking up in this e-mail, is Briffa’s concern of being left out in the cold (pun intended).

    Later Mann is saying that there are discrepancies between Phil Jones’ series and Mann’s series with Briffa’s data included.

    Mann,
    “But that explanation certainly can’t rectify why Keith’s series, which has similar seasonality *and* latitudinal emphasis to Phil’s series, differs in large part in exactly the opposite direction that Phil’s does from ours. This is the problem we all picked up on (everyone in the room at IPCC was in agreement that this was a problem and a potential distraction/detraction from the reasonably concensus viewpoint we’d like to show w/ the Jones et al and Mann et al series.”

    The ‘everyone’ in the room at IPCC said that the 2 series of graphs was a ‘potential distraction/detraction’ from Jones et al, because Briffa’s series showed a decline. That is what is inferred here.

    Then this next quote is direct collusion on Mann’s part, regarding the difference between the 2 series.
    Mann says,
    “We would need to put in a few words in this regard. Otherwise, the skeptics have an field day casting doubt on our ability to understand the factors that influence these estimates and, thus, can undermine faith in the paleoestimates.”

    Collusion, manipulation, fabrication, and omission is fraught in this one e-mail alone.

    Simply amazing.

  25. crosspatch says:

    One other pattern I find is how both Mann and Jones will come out with guns blazing when some “insignificant” person starts snooping around. If someone starts asking pesky questions, their “supervisor” and/or others at their institution are contacted, often with insulting/condescending context. Interesting. They seem to devote quite a lot of firepower to these “insignificant” pesky ones who ask questions. It is as if a hot ember has popped out of the fireplace onto the rug and they hit building halon fire suppression system to make sure the questions not only stop, but the questioner is possibly properly chastised for having the “nerve” to ask them in the first place.

    Phil Jones to Michael Wehner at Lawrence Berkeley Lab October 2007

    Hi Mike,
    Can you do a bit of discrete looking at UC Berkeley to see if this student really is a student in Physics? I’m planning to ignore the request, but am a little curious as to who the supervisor may be. I don’t think I would have had the nerve to send a request like this when I was a student. I don’t think I’d
    have the nerve to send one this blunt even now.

    It seems a pointless PhD. I would have thought that Berkeley would be above this sort of thing.

    No rush if you’re weighed under with proper work!

    Cheers
    Phil

    Insults the student, insults the PhD, insults Berkeley for even considering such a PhD. Amazing. Jones comes off with what we call in the American vernacular a little “prickishness”. There is a subtle psych play here. By insulting the institution, Jones is filling Wehner with a bunch of “oh, my God, someone is making Berkeley look bad!” sort of angst and is basically insuring that the student gets a thorough looking into.

    I would think an esteemed scientist would be above that sort of thing.

  26. DocMartyn says:

    I am not sure I buy the tmin argument. Does not altitude change the Tmin rather alot?

    Are all the tress that are merged to create a reconstruction all at the same altitude?

  27. James Sexton says:

    CheshireRed says:
    November 28, 2011 at 2:48 pm

    Daft question; has anyone else tried to re-create Manns work? Perhaps not the HS 1000 years, but what about say, the 20th century? How accurate or otherwise would other tree rings be in replicating known temparatures?
    ====================================================
    Steve McIntyre spent the better part of a decade trying to get Mann to give him the data and methodologies. Steve Mac showed the methods used would tend to give a HS graph regardless of the data. McShane and W. showed that the statistics and data used were not correct and couldn’t reasonably detect a sharp upturn in the temps. See Phil’s comment @ November 28, 2011 at 2:47 pm for a likely reason why.

    As to the question of accuracy in the 20th century, they throw out the last 40 years of the century. See my comment @ November 28, 2011 at 1:31 pm for the email stating that they do exactly that. Of course, all of this assumes one can actually detect a temp signal from tree rings. You can’t. See Doug Badgero’s comment @ November 28, 2011 at 1:45 pm for various effects on tree ring growth…also, see the growth season for the various trees. In high latitudes they don’t grow in the extended winter, regardless of the temps. So, even if one could extract a temp signal from a tree ring, it would only be representative of a partial year. So, even if you could, you can’t. Tea leaf Tree ring reading is cli-sci’s answer to phrenology.

  28. Robert Brown says:

    To follow up on John’s very cogent comment (in case Dr. Severinghaus is listening in, as he might reasonably do after posting or permitting a repost of a letter of his), there are a number of very reasonable objections one might raise to this hypothesis. One is the rather long list of things given above that are known to strongly affect tree growth and ring formation. The assumption is that everything but temperature is on average not varying, so that variation with temperature only is resolvable from the “noise” of the confounding effects across the record. This by itself seems to be a very dubious assumption, especially with regard to drought.

    Second, regarding the idea itself — that trees respire more and hence “lose more carbon at night” when night time temperatures are warmer, resulting in smaller growth rings. On the face of it, this hypothesis makes little sense. The temperature anomalies we’re talking about are what, order of 1C? Less than 1% of the overall absolute temperature. Compensating for this are: a growing season that is correspondingly longer. More moisture in the atmosphere (according to dogma associated with the high sensitivity) and less loss of water. And the really damning one — higher partial pressure of CO_2. After all, the temperature variation is a 1% effect, but the CO_2 partial pressure has increased by what, 20-30%? Isn’t that what the fuss is all about? So not only is CO_2 a fertilizer that is presumably taken up a significantly higher rate during the warmer, sunnier DAYS, but loss at night should be DIRECTLY INHIBITED by the higher partial pressure in the atmosphere compared to (say) the MWP or just the year 1900.

    You might say (Dr. Severinghaus) that these effects won’t matter, but you cannot know this without direct experimental support. So I ask — are there greenhouse studies — anywhere — that support the hypothesis that warmer greenhouse nighttime temperatures in a CO_2-forced atmosphere inhibit tree growth? I rather think not — when I look at manuals produced for actual greenhouse utilization growing plants, they do not instruct one to cool the trees — rather they claim that photosynthesis rates double with a temperature rise of 10C. This means that indeed, any “loss” of carbon at night should be more than compensated for by the 10% increased growth rate from the 1C bump average temperature, the longer growing season, and the 20% bump in available CO_2. If this is not true, we’re right back to the confounding variable problem — why is there a downtrend in growth now — it cannot just be the order 1% or so higher diffusive losses at night given the order of 10% or more gains all of the rest of the time. You might see a bit less growth than a linear hypothesis would admit, but a flatlining? An actual decrease?

    Best to say “we don’t know why the rings get smaller, but it is sufficient reason to reject them as a reliable proxy of temperature alone as there are clearly other confounding variables capable of creating natural variations in tree ring growth rates that overwhelm any possible thermal signal.”

    Otherwise, the temptation to indulge in confirmation bias is almost impossible to resist. You exclude trees from the record when they disagree with what you want them to say and include them when “they behave”. Behave according to what standard? If nothing else, if included they would CORRECTLY increase the noise on in the input data on the end you are fitting to the proxy record. This would presumably weaken the reliability of the fit throughout — if large errors can occur in trees in the fit period (grounds for rejection from the fit) they can equally well occur in the trees you include, only not during the fit period! You end up with an entirely fallacious idea of the precision and reliability of the fit if you throw out the noise.

    I encounter the same problem in random number generator testing (one of my specialities). Curiously, one of the best ways to guarantee that a given sequence of numbers is non-random is to only use it if it passes all the tests in a good random number generator tester. A perfect random number generator sometimes produces sequences that are quite ordered, ordered enough to marginally fail. What matters is the distribution and frequency of failures (at any given threshold of p for rejection) as much as successes. In order to get maximally random numbers, you have to validate the generation process, not any particular output result from that process.

    You do precisely the same thing when you cherrypick the data in any way while building proxies out of hand-picked series selected by any means other than flipping a coin or rolling dice! — by trying to pick things that “look random” around the answer you want, you guarantee that your answer is in fact neither random where you need it to be (averaging over the confounding variables) nor accurate (you’ve introduced bias) nor honest (you underreport the true variances of the result and hence overestimate the reliability of the result.

    Just a friendly thought. If there is an actual double-blind controlled greenhouse-based experiment that demonstrates that 1C warmer nighttime temperatures (all things being equal) can on average suppress growth rates of trees for the species involved, I’d be perfectly thrilled to hear about it; otherwise you are indeed simply asserting an unsupported hypothesis that might or might not be correct, where the correct default belief is incorrect, not correct.

    rgb

  29. Rosco says:

    The fact that biomass is increasing shows the flaw in the “cornerstone” of climate “science” – a radiative balance for Earth – there is no such thing – never was.

    Large amounts of energy (and CO2) are stored as biomass – if there are not significant amounts of energy stored in this manner then explain fossil fuels.

    I simply refuse to believe that a few zealots can make up some computer algorithms, squeal about doubting thomases in a vindictive manner and have any chance of being right.

    They are unco=operative with their data and methods because they know they made ridiculous mistakes and tried to cover it up with lies, deceit and venom.

    Instead of acting grown up they have put their reputations into disrepute and I for one cannot wait for the discrediting to begin. This may take some time as the MSM and politicians have a lot to lose as well but I remain convinced it will happen.

    Scepticism seems to be catching on like wildfire globally.

  30. Sean Houlihane says:

    Did climex ever get published (see foia/documents)

    The climate change experiment, CLIMEX, enclosed an entire undisturbed catchment of boreal vegetation at Risdalsheia (58.4°N, 8.3°E) within a large greenhouse. The catchment was then exposed to increased CO2 (to 560 ppmv) and temperature (+5°C in winter and +3°C in summer). Using cores taken from trees in that experiment, this study set out to establish:

    i. whether net tree productivity is increased in higher CO2 and warmer conditions (i.e. applicable to plant growth in a Mesozoic ‘greenhouse’ climate).
    ii. the nature of and extent of time dependence in the relationships between climate variability and ring width, ring density and derived ring mass change before and after the greenhouse experiment began.
    iii. quantitative estimates of growth rates and climate relationships in and outside of the experiment.

  31. jae says:

    HUH?

    The Professor says:

    “I think this is all published now so it should be possible to set the whole
    record straight.”

    I would sure like to see where this is all published. In fact, I would like to see some references to his other statments about Tmin, more respiration at night, effects of more respiration on growth rate, etc. He said in the email that he was not an expert on tree rings. Is he now saying that he IS an expert??

  32. R Barker says:

    Memo to the Team: My vote is “No confidence” in existing tree ring proxies.

    Your mission is to restore confidence in tree ring proxies. To do that, you must conduct a rather extensive experiment in remote locations of your choice, where all the significant variables are measured and /or controlled over time. Specifically grow your own trees from seedlings. This should take several decades, maybe close to a century. Report back when you can show the signature of each variable on tree rings/wood independent of the others. If you leave anything out you have to start over. ;<)

  33. JeffC says:

    His best guess ??? really ? seems like a WAG to me …

  34. JeffC says:

    ahhh … didn’t it get cooler from 1950 – 1970 ?

  35. crosspatch says:

    If there is an actual double-blind controlled greenhouse-based experiment that demonstrates that 1C warmer nighttime temperatures (all things being equal) can on average suppress growth rates of trees for the species involved, I’d be perfectly thrilled to hear about it

    I am not sure anything has been done with temperatures but I do know that tests have been done on elevated CO2. My guess is this is more speculation and computer model stuff and no empirical experimental work has been done to back it up.

    I know around here we put our plants in greenhouses to stunt their growth so the tomatoes don’t grow so large as to consume the entire neighborhood and we all know that trees get much bigger the farther North you go where temperatures are good and cold [/sarc]

  36. Smokey says:

    Thirty peer reviewed studies show that tree rings are correlated much more closely to CO2 than to temperature:

    http://climatesanity.files.wordpress.com/2010/02/correlation-coefficents-sorted-by-co2.gif

  37. Sean Houlihane says:

    People seem to be forgetting that regardless of Tmin being a hypothetical mechanism, the divergence is real (so far as we can tell with the data, hidden or otherwise). This means either trees are not thermometers, thermometers are not thermometers, or both.

  38. jae says:

    Folks: If you plot growth rate vs temperature for a tree, you will obtain a quadratic function roughly the shape of an upside-down U, which means that growth rate increases with temperature up to an optimum (around 25 C for most plants, IIRC), and then growth rate declines very rapidly with temperature after that point. SO, unless the temperatures are always below the optimum, growth rates are cannot be used as some proxy for temperature. Maybe some groves of trees somewhere have stayed below that optimum for a thousand years, but I doubt it. Then there are all the other variables that affect growth, ESPECIALLY soil moisture, which is usually much more important to growth than temperature.

    The use of tree ring width (or ring density) as a temperature proxy is so fraught with problems that it should be discontinued, IMO (maybe it has!).

    Severeinghaus knows about the non-linear relationship, because he mentioned it in the first Climategate email posted at ClimateAudit. Has he changed his tune? Professor?

  39. TedK says:

    What!? Trees respire at night? You would bring biology into an important dendro analysis? Shame on you, what are you? A real scientist?

    /sarcasm /joke **(sarcasm and joking off)

    The answer, obviously, is YES! Professor Severinghaus is a real scientist.

    Let’s see if I understand this night emission theory though. The tree respires more at night (oxygen intake, CO2 expelled) because the night is warmer… Than what? Or perhaps this a suggestion of identifying the whole diurnal temperature profile and that warmer nights might cause trees to grow less than expected? Somehow, that answer leaves me trying to understand the chemistry and biology involved. Expelled CO2 is pulling carbon from the tree so the growth ring is smaller? Trees after millions of years are so inefficient in their biology that they will fail to grow if temperatures are “off balance” and they themselves become a polluting CO2 source Someone should notify Lisa Jackson, she needs to implement immediate tree controls.

    Not to mention, it is my understanding in the nursery trade that the plants have been healthier and many growers use CO2 increased air percentages to help speed up growth. For this idea (above) to be valid, all plants would have to suffer this night time reduced growth pattern also.

    Seriously, I do not expect you to defend the theory as it sounds, to me, more like an off the top of the head strawman idea. An idea that is intended to start the thought process, not be the final opinion, at least not till after proper research is done.

    Thank you for your adherence to science!

  40. Carl Chapman says:

    I think Dr. Severinghaus is a nice guy, who can’t be brutal enough to come out and say that Mann’s dendro reconstructions are worthless. Unfortunately, people like Mann and Jones just walk all over nice guys like Dr. Severinghaus.

  41. crosspatch says:

    Continental US summer temperatures (the only temperatures that really matter for tree growth) from 1950 to 1975 show a downward trend of -0.16 degF / Decade according to NCDC.

    But the more significant problem is mentioned above. Summer temperatures do not give you a picture of the overall annual temperature. For example: contiguous US winter temperatures from 1995 to 2010 have a down trend of -1.92 degF / Decade. Summer temperatures (which would be shown in tree ring growth) trend UP at 0.63 degF / Decade. Overall annual temperatures over that period trend nearly flat at 0.09 degF / Decade. So the tree rings are only really a proxy for SUMMER temperatures and summer temperatures might be trending exactly the opposite of winter temperatures, as they are over that period in the US. Tree rings can not show whether climate overall is warming or cooling.

  42. crosspatch says:

    I believe it is stated in several places in the emails that dendrochronological data are only useful for June-July temperatures and that is what temperature data they are calibrated against. So it is quite possible for the June-July climatology for an area to be quite different from, even they opposite of, the annual climatology. So plotting tree ring proxies against anything other than June-July temperatures in any kind of a graph is intellectually dishonest. Trees don’t grow much in spring, fall, or winter but those seasons still have climate. Tree rings basically discount the climate of 10 months out of the year.

  43. Arno Arrak says:

    The argument that carbon dioxide caused the nights to be warmer and thereby influenced tree ring growth does not hold water. That is because Ferenc Miskolczi has determined that the transmittance of the atmosphere to outgoing infrared radiation has been unchanged for the last 61 years. During that same time the amount of carbon dioxide in the atmosphere increased by 21.6 percent. This means that the contribution of this added carbon dioxide to the enhanced greenhouse effect was exactly zero. Hence, increasing the amount of carbon dioxide did not warm the night air. They better start looking at the measurements that purport to show this warm night air with a more critical eye. I would like to see proof that it even exists.

  44. James Sexton says:

    JeffC says:
    November 28, 2011 at 4:07 pm

    ahhh … didn’t it get cooler from 1950 – 1970 ?
    ==============================================
    Well, during and about 1950 was marked by a particularly cold period. La Nina?……. But, you’re right, for 1940 to about the mid 70s we had a cooling trend which cause the future ice age scare….. http://www.woodfortrees.org/plot/hadcrut3vgl/from:1940/to:1977/plot/hadcrut3vgl/from:1940/to:1977/trend …… Which does call into question all the blathering about CO2. While I wasn’t alive for all of that period, I can affirm that I was alive for a good part of it. As I recall, we were industrializing even before my memory. CO2 must have been on a holiday for much of that 30+ years. It decided to quit effecting the climate then, even though it was the earlier part of the logarithmic curve. In a post I did, I “backcasted” CO2 levels to 1944 and compared them to the temps to 1977….. the assertions about CO2 sensitivity simply do not hold. Not even the most recent paper that states we overestimated the sensitivity. http://suyts.wordpress.com/2011/11/01/historical-correlations-between-temps-and-co2/ Consider the increase of CO2 emissions for over 30 years…. or nearly 40 going from under 300ppm to over 330. If the CO2 logarithmic sensitivity is correct, that should have increased the earth’s temps more than the next 30ppm, but it didn’t, the opposite occurred. And then going from 360 ppm to present, we see another gradual decrease in temps. The fact of the matter is, our temps DO NOT CORRELATE WITH CO2 EMMISIONS. For the last increase of 100 ppm ….. the first 33ppm temps went down, the next 33ppm temps went up, the next 34ppm temps are going down……

  45. Craig Loehle says:

    In 2009 I had a paper in Climatic Change Loehle, C. “A Mathematical Analysis of the Divergence Problem In Dendroclimatology” Climatic Change
    Volume 94, Numbers 3-4, 233-245, DOI: 10.1007/s10584-008-9488-8
    And analyzed the complexities of tree responses at length. The assumption of linear response MIGHT be ok for a few decades, but not when trying to detect possibly warmer periods like the MWP or colder periods like the LIA (in which more snow could cause counter-intuitive effects).

  46. Bill Illis says:

    The warmest places on the planet have no trees. The coldest places on the planet have no trees.

    Obviously, each tree species has evolved to prefer a certain temperature, a certain level of precipitation, a certain level of nutrients, a certain level of desease/insect levels, a certain level of forest fire prevalence, and all these also vary depending on the time of the year or the seasonality that each happens.

    Tree-ring widths or ring density can tell you absolutely NOTHING about temperature unless you have controlled for all the other variables and have ascertained how each one of those other variables (and temperature) can influence the data collected on ring widths or density. In March and September and for every single time of the year.

    This is, simply, an impossible task.

    Especially going back 10 years or and even more especially, 1000 years. We know nothing about desease or insects 1000 years ago for example. If you think that is not important, just search for the impacts of mountain pine beetle in the last 10 years.

    The fact that tree-rings are being used AT ALL to diagnose historical temperatures is quite frankly, RIDICULOUS.

    How this became mainstream climate science and defended to the point of actually getting people FIRED, is even more RIDICULOUS.

  47. jae says:

    Craig Lohle says:

    “In 2009 I had a paper in Climatic Change Loehle, C. “A Mathematical Analysis of the Divergence Problem In Dendroclimatology” Climatic Change
    Volume 94, Numbers 3-4, 233-245, DOI: 10.1007/s10584-008-9488-8″

    Yes. Some good evidence for obvious flaws in the ill-conceived field (?) of “dendropaleoclimatology” (funny, haven’t heard that word lately)….It is just amazing in my mind how some really, really dumb concepts gets into the mainstream thought in scientific journals. Not just in climate science. Just look at the windmill and solar cell crap!

  48. Steve Garcia says:

    [Professor Severinghaus] Trees respire more at higher temperature, so they lose carbon when nights are warmer than average.

    Huh??? Okay, the Prof just confused me.

    Our high school biology must have missed something. Don’t trees respire Oxygen? How do trees lose Carbon more at night when they respire more?

  49. crosspatch says:

    The fact that tree-rings are being used AT ALL to diagnose historical temperatures is quite frankly, RIDICULOUS.

    As I see it, it would be coincidence, at best, if a tree ring chronology anywhere matched “annual” temperature averages over any serious length of time. Imagine that a tree is a perfect thermometer for a moment. Imagine that its rings are directly related to temperature. As mentioned before, those rings are pretty much growth in only June and July.

    So instead of a tree, imagine we have several weather stations in a grid cell that only record temperatures in June and July and no other months. Those for the sake of this argument represent individual trees. Now we look at all these records and find the ones whose June-July temperatures correspond in general slope closest to ANNUAL AVERAGE temperatures over some period of time. There might actually be a few of those but that will be mostly coincidence and the fact that those stations in June-July have a series that produces a plot of about the same shape as that of average annual temperatures is chance. What are the chances that they will continue to closely match global average temperatures as we go forward in time or look at earlier times than our calibration period? Probably not very good.

    I am not saying that dendrochronology isn’t an important field of study. I am saying that plotting dendro time series data on the same graph as annual average temperatures doesn’t mean anything. They are apples/oranges. Now in the “hide the decline” graphic, Briffa’s and Mann’s dendro data first of all carry two different version of “summer” and so (I think) would have different calibration criteria. Then annual observation data are appended to the end of the graph (not “summer” observational data). So what we have is prior to the instrumentation data there are several “summer” proxies and annual instrumentation data tacked on at the end.

    Imagine taking a census of the number of students attending classes in June and July and graphing that over time and then at the end of the graph you append the annual average of the number of students that attend classes. The graph would be meaningless, wouldn’t it? Because the early part is a graph of apples and the late part is graph of oranges. But they merge them together because the picture it presents is what they want people to believe. It really, really, gets the “point” across even if it is fiction.

    What I find hard to believe is that anyone would take the graphic seriously in the first place let alone dissect it to any degree. The whole premise of the graphic is preposterous. It might have SOME modicum of validity if only June-July NH average temperatures were plotted. But the caption of the original “hide the decline” graphic said:

    Figure 6. Northern Hemisphere temperature reconstructions from paleoclimatic sources. The three series are Mann et al. [1998, 1999] (thick), Briffa et al. [1998] (medium) and Jones et al. [1998] (thin). All three annually resolved reconstructions have been smoothed with a 50-year Gaussian filter. The fourth (thickest) line is the short annual instrumental record also smoothed in a similar manner. All series are plotted as departures from the 1961–1990 average.

    That right there is reason to demand that the instrument series be removed from the graphic. You can not compare summer only data with annual data (well, you CAN, if you are trying to show a difference between them). Why didn’t that get ripped out in review? Why were they surprised that they diverged? Why were very specific regional data (the dendro time series) completed with annual averages for the entire NH? I would have chosen the instrumentation data for the grids where the trees were located for June and July and then maybe I would have had something, unless the June-July temperatures in those actually declined, too (as happened in North America after 1950). Then maybe the “divergence” problem goes away if you do that but the graph doesn’t have the desired trend anymore.

    At best tree rings can be a June-July proxy and that’s it. They reflect growing conditions during the part of the year when growing happens. They can’t much reflect conditions occurring when there isn’t much growing going on.

  50. Dave Dardinger says:

    DocMartyn said:

    I am not sure I buy the tmin argument. Does not altitude change the Tmin rather alot?
    Are all the tress that are merged to create a reconstruction all at the same altitude?

    I’m Glad you bring that up. Fairly early on at Climate Audit, Steve Mc had a post about some (Russian?) researchers who did a transit of a mountain to get cores from a group of trees at various altitudes to see how that affected the tree rings. I don’t remember the results, but the post should be looked up and we might be able to judge how Dr. Severinghaus’ idea holds up.

  51. Johnnythelowery says:

    Darlings: Um……….excuse me a minute. Trees don’t perspire Carbon. They take the C for carbon and the O(2) for oxygen and they retain carbon and expire……..Oxygen. There will only be a correlation between carbon in-take and the availability of carbon to be in-taked. There is no Out-put of Carbon and so the idea is PhilJonesean. But maybe it plots on Excel. Question: in what ‘format’ is Carbon expired???????? Cheers………… Joe Public.

  52. crosspatch says:

    Plants also have respiration and also release CO2 in addition to taking it up.

    But it is all overblown anyway. If you have a fully mature forest that is no longer putting on net biomas, it is a net zero for carbon sequestration. “Old growth” forests provide no net reduction in atmospheric CO2. For every young tree that is growing putting on carbon, one is decaying releasing carbon. For every new branch sprouted, one is broken off from wind. At some point at full maturity, the forest stops adding net carbon biomass.

    The best way to reduce CO2 is to plant fast growing trees, cut them down for paper, sequester the paper in a landfill. Paper recycling actually increases the rate of atmospheric CO2 increase by reducing the rate of tree planting for paper.

    The second best way to reduce CO2 growth is through “sustainable” logging and forest management techniques that allow selective logging of the oldest trees in a mixed age forest and forest floor fuel management by regular controlled burning of the underbrush to prevent fuel load buildup resulting in extremely destructive, very hot fires.

  53. Steve Garcia says:

    Johnny -

    That was my point, that though trees take UP Carbon, but Prof Severinghaus said “…Trees respire more at higher temperature, so they lose carbon when nights are warmer than average.” [emphasis added]

    That was what confused me. If they breathed more on warmer nights would they not gain Carbon?

    Maybe not. Hattenschwiller et al 2006, titled Tree ring responses to elevated CO2 and increased N deposition in Picea abies in its abstract reads [emphasis added]

    ABSTRACT

    Four- to seven-year-old spruce trees (Picea abies) were exposed to three CO2 concentrations (280, 420 and 560 cm3 m−3) and three rates of wet N deposition (0, 30 and 90 kg ha−1 year−1) for 3 years in a simulated montane forest climate. Six trees from each of six clones were grown in competition in each of nine 100 × 70 × 36 cm model ecosystems with nutrient-poor natural forest soil. Stem dises were analysed using X-ray densitometry. The radial stem increment was not affected by [CO2] but increased with increasing rates of N deposition. [This seems to be atlking about ring widths...] Wood density was increased by [CO2], but decreased by N deposition. [This says that though the width wasn't affected, the density WAS.] Wood-starch concentration increased, and wood nitrogen concentration decreased with increasing [CO2], but neither was affected by N deposition. The lignin concentration in wood was affected by neither [CO2] nor N deposition. Our results suggest that, under natural growth conditions, rising atmospheric [CO2] will not lead to enhanced radial stem growth of spruce, but atmospheric N deposition will, and in some regions is probably already doing so. Elevated [CO2], however, will lead to denser wood unless this effect is compensated by massive atmospheric N deposition. If can be speculated that greater wood density under elevated [CO2] may alter the mechanical properties of wood, and higher ratios of C/N and lignin/N in wood grown at elevated [CO2] may affect nutrient cycles of forest ecosystems.

    Though this doesn’t specifically address the question I asked – about Prof S’s comment about warmer night temps – it does seem to relate to increased CO2 availability and intake converting to denser tree rings. I can only assume this is is talking about atmospheric CO2. That would seem to contradict the Professor’s statement – and would seem to agree with you and me.

    I think the professor may simply have misspoke. But this applies only to spruce trees, as far as the study spells out. Still, though extrapolating it to other trees may not be quite correct, it does seem a reasonable assumption.

  54. Juraj V. says:

    Never seen serious study comparing daily minimums and maximums and attributing night warming to GHE. Of course, night warming is also prone to UHI.

  55. Don K says:

    R Barker says:
    November 28, 2011 at 4:00 pm

    Memo to the Team: My vote is “No confidence” in existing tree ring proxies.

    Your mission is to restore confidence in tree ring proxies. To do that, you must conduct a rather extensive experiment in remote locations of your choice, where all the significant variables are measured and /or controlled over time. Specifically grow your own trees from seedlings. This should take several decades, maybe close to a century. Report back when you can show the signature of each variable on tree rings/wood independent of the others. If you leave anything out you have to start over. ;<)

    ==========

    All true enough. But there is this other problem that tree ring proxies for the most recent six decades apparently aren't behaving as it is thought they should compared to older data. That implies that even decades of research on how variables affect trees growing today/tomorrow may not reveal much about older data — unless of course the older data is being misassessed.

    On top of which, I kinda, sorta, suspect that just maybe tree growth variations wrt temperature, precipitation, et al might vary with species, altitude, soil chemistry, etc.

  56. crosspatch says:

    I have seen experimental results only on conifer species. In those species, elevated CO2 does two things: 1) it accelerates growth and 2) it GREATLY increases the number of viable seeds produced. The growth increase is 2 to 4 times depending on the species. Seed production can be as much as 10x increased. That actually makes sense in other contexts. Gymnosperm species were dominant when CO2 levels were highest. Angiosperm species take over as CO2 levels drop. They (the broad leaf species) also tend to conserve their CO2. In the fall they drop their leaves. In the following year, these decompose releasing CO2 that the forest takes up again. The conifer species drop needles but these tend to decompose only very slowly often taking many years due to the resins they contain acting as a preservative. Those resins tend to act to poison the ground to make it more difficult for other species to invade. But as CO2 levels drop, the conifers produce fewer seeds. CO2 doesn’t seem to have quite as dramatic impact on seed production of broad leaf species.

    One thing I might look for if atmospheric CO2 is increasing is to look at areas such as Northern California where you might have a margin of Douglass fir meeting a mixed oak/madrone forest. I would expect to see the fir trees starting to expand their range and start moving into the areas that had been mostly oak/madrone. And in fact I do see just such an occurrence though it might just be local to that specific area. I have a friend with about 500 acres in Mendocino County, California. On this property, over the past 5 years, the Douglass fir seedlings have begin encroaching into the oak and madrone area. My friend regards the firs as weeds and they seem to be a bit vexatious in their spread into the hardwood tree area. It seems to be almost a reverse forest succession with a conifer species starting to crowd out hardwoods.

    I would also be interested in any changes recently in the populations of Araucaria globally (“Monkey Puzzle” trees, Norfolk Island pine, Bunya-bunya, etc.) These trees are a VERY old line which evolved when CO2 levels were much higher than today. I wonder if they are doing better now that CO2 levels are higher. Are wild Norfolk Island pines suddenly increasing in number?

  57. crosspatch says:

    Never seen serious study comparing daily minimums and maximums and attributing night warming to GHE. Of course, night warming is also prone to UHI.

    GHE would be expected to have its greatest impact in reducing the total radiation of infrared into space. This would have an impact of moderating nighttime low temperatures. It is also the reason why the GHE would be expected to have its greatest impact at the poles because with six months of nighttime, one would expect to see even a small change in the amount of infrared re-radiated back to the surface to have a larger impact. Greenhouse impacts would not be expected to have as much impact on daytime highs because they would also block inbound long wave IR directly from the sun. So what would be expected is actually a moderation of daytime highs and nighttime lows. In an extreme greenhouse such as venus, there would be little difference between daytime and nighttime temperatures.

  58. Ralph says:

    >>There really is a problem
    >>with the trees not being sensitive to temperature after about 1950. My
    >>current best guess is that the higher CO2 since then has caused greater
    >>warming at night (which is corroborated by minimum temperature trends,
    >>since minimum temperatures usually occur at night).

    Do I spy some circular type arguments here?

    Ok, so in the modern era, the tree rings are smaller than would be expected because of night temperatures – hence the decline that had to be hidden by YAD061.

    But the same would have happened in the Roman and Medieval warming periods. Thus Mann’s historical temperature record should have shown two decreases in temperature for these warming periods. But it does not. Methinks the technique stinks.

    .

    But I shall say it once more – if so, how on earth can dendrochronology work?

    If I had taken a core from YAD061 (the tree with exponential growth) and compared it with the reference tree-ring record, there would have been no match whatsoever. So no date comparison would be possible.

    Likewise, if I took a timber from an ancient ship, that came from a tree that was intermittently attacked by pests and had significant decreases in growth ever ten years – how on earth can I compare that to a reference tree-ring record that had no pest infestation?

    If tree-rings record local events (reeeaaaly local events, like the big tree next door being blown over), then how can they be compared to a reference record from thousands of kilometers away? And if they cannot be compared, then how on earth can dendrochronology work??

    .

  59. John Brookes says:

    I’ve occasionally wondered if the effects of air travel are adequately accounted for. A country like the US is absolutely criss-crossed with jet exhaust trails, but this has really only been from half way through last century.

    Trees at altitude might be more effected by high cloud than those nearer to sea level.

  60. tallbloke says:

    “Trees respire more

    at higher temperature, so they lose carbon when nights are warmer

    than average. So their ring width has not increased as much as it would

    have if the warming had been uniformly distributed over the diurnal cycle.

    I think this is all published now so it should be possible to set the whole

    record straight. “

    Could Jeff be more specific with some cites here?

  61. Pamela Gray says:

    Crosspatch!!! Toms grown in hothouses to prevent overgrowth? Puter screen meet coffee spit!!!!!

    On the serious side, I’m betting that winter snow pack and summer ground water affects tree-ring growth season a great deal more than nighttime summer temps. Here’s an idea. Ask an established, for profit forest land owner this question: Which variable do they lose sleep over? Oh yeh. Can’t. They haven’t published let alone been peer reviewed. They just sell trees.

  62. LazyTeenager says:

    John says
    The other thing is that CO2 is a fertilizer. The Idsos and many other researchers have shown time and again that plants grow more quickly with more CO2. Tropical trees and temperate trees add more carbon lately, in our now higher CO2 environment, we’ve seen in a number of studies. So if the trees add more carbon, why would tree rings show less growth?
    ————
    Trees photosynthesise during the day and respire both day and night. So tree growth is the net effect of photosynthesis (CO2 absorption) and respiration (CO2 expiration). Respiration increases with temperature. Photosynthesis is affected by temperature and the amount of CO2 in the air. So if nights are warm respiration may partially cancel out the increased daytime photosynthesis.

  63. coturnix says:

    that the higher CO2 since then has caused greater

    warming at night


    Increase in co2 will decrease nighttime temperatures. Explanation: nights are cooler than days because some of the heat escapes though the window(s) in the ghg absorption spectrum. CO2 increase does nothing to window(s) width, but it will decrease the depth of nighttime inversion, because in denser co2 atmosphere the ability of free troposphere above to warm surface is diminished. That’s why more co2 = more contrast between days and nights, which means either colder nights or warmer days, or increase in daily lows but not as fast as of daytime highs.

  64. Well there may be some link somewhere between some tree species and local temperatures, but when we look at 150+ years of temperature records in northern Russia, the tree ring records really do not correlate at all, whereas the thermometer records correlate well with each other.

    Treering records should not be smoothed. The correspondences between years (the “lacework details” of the thermometer records are just as important as the longer-term correspondences, to determine usefulness as proxies.

    See my work on all this.

  65. Phil says:

    Craig Loehle, your paper makes (much more elegantly, and completely) the same point I made in a post up above. Nice work, it appears that my supposition has some merit.

    To use Sean Houlihane’s phrasing, what if trees ARE thermometer, but only over a modest range of temperatures? Then we can use the tree data to estimate temperature in the past, and get much of it right, but we won’t know if there are any extremes. If we only cared about the modest ranges, this would be fine, but since we are precisely interested in the extremes, and that is where the trees fail to deliver, the tree rings can’t be used to falsify the possibly of historical warm periods.

    (Nice paper, BTW)

  66. Pamela Gray says:

    CO2 can only cause indirect warming at night. Surface land and ocean temps cool at night via radiation and at different rates. In dry atmospheric conditions, that cooling can be quite impressive. Cooling is tempered by cloud cover (IE an abundance of water vapor). If diurnal temps have increased in this case, the AGW hypothesis would be of course that night time air must be anomalously humid to cause this warming, and that this additional cloud producing humidity must be caused by the portion of CO2 that is AGW CO2.

    I would ask the doctor for observational based (not modeled) references before this can be accepted. There are very powerful natural long and short term cloud producing mechanisms that readily temper night time cooling. That we can place this tempered cooling related to these trees on the back of such a tiny increase in CO2 is quite a stretch.

    There is an old saying in medical circles: You must rule out the first encountered pathology. And the first encountered pathology must be short and long term natural weather and climate variation.

  67. Red Etin says:

    What temperature is important to a tree? The outside temperature or its internal temperature? I would have thought the latter will influence its metabolic rate.
    http://www.fabinet.up.ac.za/sirexweb/sirexlit/Jamieson1957NZJFor.pdf

  68. Kay says:

    Severinghaus says that warmer nights mean that trees respire more CO2, hence have less carbon to add to tree rings? That’s very interesting, but I’m not so sure he’s right. It has less to do with CO2 and more to do with the way plants function at night under different day/night temperature conditions.

    I’m not a botanist, but I am an avid gardener. Ambient CO2 levels naturally go UP at night because the plants aren’t taking it in. But respiration doesn’t depend on sunlight and occurs not just at night but during the day, too. They not only produce CO2 but release energy and consume O2. On balance, though, the plants take in far more CO2 than they respire.

    Now, many species of flowering plants (I know, we’re talking about trees, but I can’t imagine the processes would be any different) grow well ONLY when temperatures during the part of the diurnal cycle that normally comes at night are lower than temperatures during the day. Yes, plants and trees are diurnal and certain functions and processes are more efficient at certain times. For example, cell division takes places just before dawn.

    In other words, some species only do well when there is a big enough difference between daytime and nighttime temperatures. If the nighttime minimum temperatures are too warm, it affects plant growth by not exerting enough pressure on the root systems, which affects calcium distribution (and other compounds) to the leaves, buds, and flowers by slowing it down. Too-warm nighttime temperatures also rapidly speeds up respiration, which causes the plant to burn through the assimilates (sugars) it created during the day via photosynthesis. (Cooler temps at night also promotes sugar transport.) When that happens, plant growth is severely limited.

    So I think Severinghaus is half-right. He’s in the right church, but the wrong pew. CO2 level has nothing whatever to do with it.

  69. Tilo Reber says:

    “Severinghaus says that warmer nights mean that trees respire more CO2, hence have less carbon to add to tree rings?”

    Severinghaus is simply pulling it out of his backside. If this idea made sense, then you would get smaller tree rings, even if both day and night warmed together. None of this is driven by any experimental data. It’s a theory made to fit a need, while at the same time trying to retain the idea that trees can be used as thermometers. I saw Mann give a speech at some university where he claimed that the smaller tree rings were due to pollution. What he means by pollution, especially in the remote places where these studies were made, we do not know. Basically they will say anything – make up any excuse – to keep from admitting that trees are very poor thermometers and that the problems being experienced today could well have been happening at other times in the record as well.

  70. JPeden says:

    My current best guess is that the higher CO2 since then has caused greater
    warming at night (which is corroborated by minimum temperature trends,
    since minimum temperatures usually occur at night).

    I thought the increased minimums have mostly occurred in Winter. In cities.

    Trees respire more at higher temperature, so they lose carbon when nights are warmer
    than average. So their ring width has not increased as much as it would
    have if the warming had been uniformly distributed over the diurnal cycle.

    I’ve found info indicating that roots grow at night at a rate greater than the average, according to an official summary of this question I’d have to go find again. This should help a tree grow rings. And do the rings grow at night using the same respiratory mechanism, given energy availability? Otherwise, it appears that no one knows enough about roots in general.

    If he’s talking about the increase in respiratory energy lost at night with warmer temps, then another question is, even if it is even significantly “lost”, can it be effectively compensated for, if needed, during the day by photosynthesis. Trees seem to be very specialized and adaptable at the same time.

    Too many variables, especially with wild trees, where no one knows what has gone on both below and above ground throughout each of their histories. That’s why they’re called “wild”.

  71. Gail Combs says:

    I have not read the comment yet so forgive me if this point has already been brought up.
    >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

    …..There really is a problem with the trees not being sensitive to temperature after about 1950. My current best guess is that the higher CO2 since then has caused greater warming at night (which is corroborated by minimum temperature trends, since minimum temperatures usually occur at night)…..

    >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
    ERRRRrrrr, there is directly measured evidence that this is not the case.

    This is a guest post by Philip Bradley….
    An analysis of Australian temperature data recorded at fixed times, and the implications for the ‘global average land surface temperature’ derived from minimum and maximum temperatures

    Jonathan Lowe, an Australian statistician, has performed extensive analysis of weather data recorded at fixed times by Australia’s Bureau of Meteorology (BoM). This analysis is available at his blog, A Gust of Hot Air. The data comes from 21 weather stations manned by professional meteorologists….
    1. Using a minimum and maximum temperature dataset exaggerates the increase in the global average land surface temperature over the last 60 years by approximately 45%

    2. Almost all the warming over the last 60 years occurred between 6am and 12 noon

    3. Warming is strongly correlated with decreasing cloud cover during the daytime and is therefore caused by increased solar insolation…
    Part 2 – Almost all of the warming over the last 60 years occurred between 6am and 12 noon

    Jonathan uses the simple but elegant method of subtracting the temperature at one three-hour interval from the temperature at the next three-hour interval to determine at what times of day the warming over the last 60 years has occurred. This breaks down the total warming over the last 60 years into three-hour slices of the day.

    You can see his graphs here – http://gustofhotair.blogspot.com/2009/04/analysis-of-australian-temperature-part_16.html

    He finds that warming has occurred in only three of these time slices; 6am to 9am, 9am to 12 noon and 6pm to 9pm. The other five three-hour time slices show either a cooling trend or no significant trend.

    In parts 3 and 4, I discuss physical mechanisms that would cause temperature rises to be restricted to these time periods.

    Jonathan’s analysis shows that there has been no warming occurring at nighttime at all since 1950. Although nighttime temperatures have risen due to residual heat from warmer days.

    http://bishophill.squarespace.com/blog/2011/11/4/australian-temperatures.html

  72. Theo Goodwin says:

    Tilo Reber says:
    November 29, 2011 at 7:52 am

    As many have pointed out, including Tilo, there has been no empirical research that can tell us why tree ring width declined. What The Team have offered and offers is nothing but hunches. Until there is empirical research on at least one variety of tree that can tell us about the changes in growth rates for tree rings and the environmental changes that cause them, tree ring data cannot be used as a proxy for temperature. This applies to all tree ring data extending into the past. That tree ring data has not been supported through empirical research.

    The point should be extended to all paleo data. Paleo data is used today only because it has been used in the past. But none of it, present or past, has been subjected to serious empirical research that would provide some support for the data and, more important, some scientific basis for distinguishing good paleo data from bad. By contrast, archeologists can use radiocarbon dating to assign dates to historic and pre-historic artifacts with reasonable confidence because there is a well-confirmed science that explains techniques of radiocarbon dating. There is no such thing for tree rings as proxies for temperature. For that reason, all claims based on tree ring proxies must be treated as hunches and not genuine science.

    This message came to The Team more than a decade ago from prominent scientists, such as Professor Daly, who warned them that they must adopt scientific method in the practice of paleoclimatology. I am sad to say that I have come to believe that the members of The Team truly do not understand the message. They truly do not understand that their claims about tree rings as proxies for temperature are not empirical claims at all. These studies must be rejected because there is no empirical support for them. All articles by The Team that rely on tree ring width data, past and present articles, must be withdrawn.

  73. JPeden says:

    Tilo Reber says:
    November 29, 2011 at 7:52 am

    “Severinghaus says that warmer nights mean that trees respire more CO2, hence have less carbon to add to tree rings?”

    Severinghaus is simply pulling it out of his backside.

    Amen. As usual the Climate Scientists just make it up to [not] fit. And now those increased temps. at night are gonna kill trees, QED!

    But they should have stuck to blaming the Moon. That does fit.

  74. JPeden says:

    “Gail Combs says:
    November 29, 2011 at 10:07 am”

    Dittos. http://gustofhotair.blogspot.com/2009/04/analysis-of-australian-temperature-part_16.html

    I got to Lowe’s site last night while looking for night time minimums. But it’s only Australia, dontcha know, so it doesn’t “fit”.

  75. Steve Garcia says:

    @Theo Goodwin says:
    November 29, 2011 at 10:15 am

    As many have pointed out, including Tilo, there has been no empirical research that can tell us why tree ring width declined. What The Team have offered and offers is nothing but hunches. Until there is empirical research on at least one variety of tree that can tell us about the changes in growth rates for tree rings and the environmental changes that cause them, tree ring data cannot be used as a proxy for temperature.

    Actually, as to empirical studies, the Hätteneschwiler, Schweingruber and Körner 2006 paper “Tree ring responses to elevated CO2 and increased N deposition in Picea abies” (http://tiny.cc/v6fve) does this for spruce trees, for elevated CO2 and Nitrogen. That is not the only environmental change that needs to be looked at, but it is at least a start.

    I agree. NONE of the claims of tree rings as proxies – no matter how suggestive or reasonable sounding – should be considered valid until the ALL the underlying assumptions are empirically tested – and quantified. Prior to that, it is no more science than Plato and Aristotle conjecturing back in ancient Greece – it all sounds good, but it isn’t science.

  76. Theo Goodwin says:

    Steve Garcia says:
    November 29, 2011 at 10:51 am

    “Actually, as to empirical studies, the Hätteneschwiler, Schweingruber and Körner 2006 paper “Tree ring responses to elevated CO2 and increased N deposition in Picea abies” (http://tiny.cc/v6fve) does this for spruce trees, for elevated CO2 and Nitrogen. That is not the only environmental change that needs to be looked at, but it is at least a start.”

    Yes, it is a beginning. I am glad someone is beginning empirical research on tree rings.

    “I agree. NONE of the claims of tree rings as proxies – no matter how suggestive or reasonable sounding – should be considered valid until the ALL the underlying assumptions are empirically tested – and quantified. Prior to that, it is no more science than Plato and Aristotle conjecturing back in ancient Greece – it all sounds good, but it isn’t science.”

    Absolutely, the fact that non-empirical work is passed off as empirical work is one of the two great scandals of the Hockey Stick. The other is the magical statistics identified by McIntyre.

    No wonder they thought hide “hide the decline” did not matter; it was an empirical matter and they have no understanding of empirical matters at all.

  77. Tom Davidson says:

    “My current best guess is …” still just a guess.
    Empirical data is validated only by measurements, not by speculations.

  78. Steve Garcia says:

    @Theo Goodwin 11:10am:

    A true tale:
    I worked 7 years in industrial R&D, and one project was an ongoing prototype machine that was used to test principles. Amazingly, for the first few years my chief scientist did not do empirical tests using the scientific method. Whenever there were problems, he would use his understanding of all the complexities to direct us toward solutions – but there was always a lot of spinning our wheels, because many of his “solutions” happened to be hip-shooting (which only became obvious later on). Eventually they took him off that project and put someone else in his place. The first thing the new scientist did was to begin creating a matrix of what happened when ONLY one parameter was changed at a time. Within a few weeks we had a large display board that was quantified (even visual, it turned out). When problems came up, we were almost instantaneously able to identify which parameter had slipped out of adjustment. Though both were PhD level scientists, one was a hipshooter and one was a methodical scientist. In a complex environment with scores of parameters, the method man’s science worked.

    I see that experience as a direct parallel to climate science, since both are complex environments with many variables – and because the solution isn’t to go on a scientist’s speculations on what is going on, but to identify what happens when each parameter changes. Needless to say, climate science has not done its homework – yet. I am very hopeful that some day that will change. Who knows? Maybe once climate scientists do their homework they might find the hip shooters are right. I am convinced they will find the hip shooters are wrong. The Team is no more than a bunch of statistics-crunching desk jockeys, who revel in flying all over the world attending conferences and pontificating. What is needed is method men, empirically solidifying the “known” – so that, for example, water vapor is not a “great unknown greenhouse gas.” When enough knowns have been worked out, climatology will be a science; until then it is kind of like astrology. Blame that on Mann and Jones et al.

    (Perhaps The Team should even be called “The Astrologers.”)

    Until they get the numb nuts out – the hip shooters – they are just in the way. But more than just in the way, events have conspired to put the numb nuts in the ear of policymakers, whom the numb nuts have convinced to destroy the western economies, based on the hip shooting. THIS is why skeptics like myself are so hyper about getting these idiots out and putting real scientists in – and getting rid of the IPCC, out of which no good can come. It is a case of “When will they put actual adults in charge?” (Michael Mann, you know of whom I speak…)

  79. Gail Combs says:

    JPeden says:
    November 29, 2011 at 10:47 am

    “Gail Combs says:
    November 29, 2011 at 10:07 am”

    Dittos. http://gustofhotair.blogspot.com/2009/04/analysis-of-australian-temperature-part_16.html

    I got to Lowe’s site last night while looking for night time minimums. But it’s only Australia, dontcha know, so it doesn’t “fit”.
    __________________________________________
    At least it is ACTUAL DATA from ACTUAL MEASUREMENTS. Of course climate scientists wouldn’t know what actual in field measurement s ARE, much less how to make them. /snark>

  80. Steve Garcia says:

    @Theo Goodwin at 11:10 am:

    No wonder they thought hide “hide the decline” did not matter; it was an empirical matter and they have no understanding of empirical matters at all.

    Correct. When they saw the divergence, first hand, they should have stopped and asked “What does this mean?” (Perhaps they did ask – not for the science but for their agenda – and that is why they needed to hide the decline; like Judith Curry, it did “the cause” no good to put out there, for all the world to see, that there was a divergence problem. The original Climategate emails clearly showed them conspiring to not let it “weaken the message.” DO note that Briffa was strongly against this action, but in the end he crumbled under Mann’s boot heel.)

    Asking “What does this mean, would have led real scientists to institute new empircal studies to identify the reason behind the divergence. Leaving such a narrowly-focused area unclear – how in the WORLD is that science – when they were the supposed top people in their field, it was their responsibility to eliminate the uncertainty of the divergence. Leaving it to others is just not cool. Hiding its very existence from the policymakers and public was even worse.

    But, being mere desk jockeys, as you say, they had no understanding of empirical matters at all. That has become more and more clear in reading the emails. Show me ONE empirical paper – listed in the emails or elsewhere – that was authored by a Team member. They were all only “reconstructors.”

  81. Gail Combs says:

    Steve Garcia says:
    November 29, 2011 at 12:10 pm

    @Theo Goodwin 11:10am:

    A true tale:
    I worked 7 years in industrial R&D, and one project was an ongoing prototype machine that was used to test principles. Amazingly, for the first few years my chief scientist did not do empirical tests using the scientific method…..
    ____________________________________
    YES!

    I was considered a great “trouble shooter” Yet all I did was go out to the plant floor and ASK the operators what was going on, what had changed… When necessary another guy and I would set up and run fractional factorial experimental designs. This was before computers were available so the number crunching was done with hand calculators. (ARGHhhhh) It was well worth it though. We got clear pictures of what was causing problems to happen.

    This hand waving and calling it “Science” makes me sick.

  82. Theo Goodwin says:

    Steve Garcia says:
    November 29, 2011 at 12:10 pm

    Very well said. I endorse every word.

    I would add that “noble cause corruption” or something like that resides in the hearts of the Climategaters. I believe that they saw that the nascent field of climate science presented many opportunities for political gains and they took advantage of the infant and bent it to their ends.

    My main reasons for believing this are two: 1) not one of The Team has the instincts of a genuine empirical scientist and 2) they have produced 99% hype based on 1% empirical science and all of that science was inherited. They inherited items such as tree ring width as proxy for temperatures but never investigated its empirical foundations and then made outrageous claims on the basis of it, claims such as those found in the Hockey Stick.

    What skeptics have been trying to do and are trying to do is simply to call attention to the non-existence of the science that underlies mainstream climate science today. There is no empirical justification for using tree ring width as a proxy for temperature. That claim has been established beyond reasonable doubt. Yet skeptics cannot get the attention of the MSM or mainstream climate science and get them to address the matter. All we need is a fair hearing.

    By the way, I worked in situations similar to the one describe. I managed models for some time and my most difficult task was explaining to the engineer users that the model is not a description of reality. Then I had to explain to them how to observe the behavior of the models and how to create those matrices that you describe above so that we could have rational debate about what a model run shows.

  83. treegyn1 says:

    As a forester with 30+ years experience, let me add a few words about tree ring width. Radial growth of trees (and height for that matter) is driven by available resources during the growing season, a growing season that varies from year round in the case of Eucalyptus species, to only a month or so at the tree line or edge of the tundra. The key resources are: solar radiation, water availability, nutrients, and temperature. Because trees are mostly very long lived, outcrossing higher plants that are unable to migrate south for the winter, they became genetically adapted to the prevailing “environmental” conditions of the region in which they reside.

    However, consider that many tree species live for many decades, some for many centuries, so have the genetic capacity to sustain, survive, and reproduce effectively under a wide range of temperatures, dry/wet cycles, and other weather phenomena. To cut to the chase, excepting for those trees forced into genetic dead ends with limited population sizes, trees contain tremendous amounts of genetic variation that enable them to survive for long stretches of time under highly variable conditions.

    In my experience, tree ring width is limited primarily by available water, and by pandemic insect attacks (which reduces the ability of surviving trees to take up water and nutrients). Droughts and insect epidemics often run for several years, showing a characteristic reduction in tree ring width. Density of stocking is also important. 400 trees per acre won’t affect ring width much when the stand age is say, 20-40 years but eventually, competition between trees within the stand becomes intense and ring width drops dramatically. In cooler years in the temperate zone, tree growth is also reduced, but in my experience this is due more to increased cloud cover (less solar radiation). Tree radial growth can also be abruptly halted from unseasonably early (or late) hard freezes, but we rarely see this more than a year or two consecutively.

    Thus I concur, but for different reasons, that trees make lousy thermometers.

  84. Steve Garcia says:

    Yes, Gail -

    It is amazing when solid work is done, because it can be then used in the real world. I like to remind people that engineering is science, too – the term I was taught is “applied science.” But I take it one step further and say that when it is nailed down 100% it stops being science and becomes engineering. And the corollary to that is that until it is engineering it is just playing around with lab equipment or running around in fields. That in no way, though, puts engineering above theoretical science (the non-engineering side of science). It is just that the purpose of science in the first place is to serve mankind in a practical way. The discovery aspect is only a phase on the way to making it all work – and nothing but empirical results are important toward that end. Theories are nice and models are nice – BUT DO THEY WORK? Until they work they are farts in a windstorm.

    One of the scientists with whom I worked (Oxford educated) was really good about taking what he called “intuitively correct ideas” and coming up with finding ways to prove them out. He knew the difference between what sounded right and what was proven to BE right.

    MUCH of what an engineer does is knowing what does not work. Much of what a “scientist” does is finding reasons why an idea won’t work. Sometimes that takes experiments. Sometimes he can run it through his mind and see enough clear flaws to reject the idea. In Prof. Severinghaus’ emails, one can see that he saw flaws in the premise of tree ring proxies, due to the divergence problem and it alarmed him.

    I think the divergence problem should actually be called the Divergence Paradox. What Severinghaus saw was a paradox – something that didn’t fit. And when paradoxes exist, something in the underlying paradigm (or stated premises) has to be wrong. It is then important to find out what premises are wrong.

  85. Steve Garcia says:

    @Theo 12:44 pm:

    I would add that “noble cause corruption” or something like that resides in the hearts of the Climategaters. I believe that they saw that the nascent field of climate science presented many opportunities for political gains and they took advantage of the infant and bent it to their ends.

    My understanding is that this all goes back to Hansen, to Lovelock’s Gaia concept, the “Small is beautiful” (SIB) ideas of EF Shumaker, plus the types of people who went into the environmental earth sciences like oceanography – all basically adherents of Gaia and SIB. (The “coming ice age” concept of the middle 1970s came from Woods Hole and from East Anglia.) I think that nearly 100% of the participants came into the field with the idea that mankind was raping the natural world. The Gaia and SIB concepts included the idea that the Earth as a consciousness would some day strike back. Lovelock came up with the concept ironically just as the U.S. Congress was passing the Clean Air Act and the Clean Water Act. If you are old enough, you know what real pollution is (and it ain’t what we have now!). Lovelock’s ideas were going to come from someone at that time, if not him. The SIB principle is what much of the goals of the warmers and the IPCC is based – to shrink western technological society to the backyard organic farmer level – a completely unsustainable concept in a world of (then) 4 billion or (now) 7 billion, without lowering the population to 1 or 2 billion. But the warmers don’t understand that what they propose is magnitudes worse than Stalin’s 35 million dead. Every aspect of what they want is to return the world to pre-Inustrial Revolution times – and that simply isn’t possible without a horrible killing off of people.

    Along with the above ideas, let us not leave out the Malthusian “genius” of Paul Ehrlich, who predicted we’d be out of iron, coal, oil, copper, land, food. Ehrlich did not give any credence to future improvements in crop yields or oil finds. We are, in fact, no worse off now than when he spouted those dire predictions of gloom and doom. We are probably better off now, since so much of he world’s prosperity has actually increased since he wrote in the 1970s. I wouldn’t have believed then the world could sustain 7 billion, but here we are.

    So, these folks have all that running around in their heads – all Chicken Littles, feeding off each other and denying the evidence all around them. It is my definite impression that they WANT the world to collapse, to prove their mentors’ predictions. I think they expect it any day, very much like the 2012 end of the world stuff or the Jamestown people.

    My main reasons for believing this are two: 1) not one of The Team has the instincts of a genuine empirical scientist

    That seems true.

    and 2) they have produced 99% hype based on 1% empirical science and all of that science was inherited.

    If not true 100%, then at least not far wrong. But don’t forget that to them it is not hype – it is what they believe: The world stands on the brink. But since Malthus, the world has had people rending their clothes about this. This just happens to be the first time they’ve been in a position to affect government policies.

    …There is no empirical justification for using tree ring width as a proxy for temperature.

    Actually, not true. The proxy has been fairly reliable and documented. It is only that it is not always linear that has caused problems.

    As Craig Loehle points out in his paper, if today’s warming is not reflected in the tree rings, then what does this tell us about such periods as the MWP and the Roman Warm Period? If it has flattened out since 1950 or 1960 (actually declined by 0.4C, based on the linearity assumption), then the linearity in the 900AD-1400AD period has to be in question, too. it suggests that the MWP may have been as warm or warmer than today – and that the tree rings wouldn’t even tell us. THIS is one of the real big problems for climatology – a really big deal.

    Without linearity, is the tree ring proxy status endangered? I think so.

    By the way, I worked in situations similar to the one describe. I managed models for some time and my most difficult task was explaining to the engineer users that the model is not a description of reality. Then I had to explain to them how to observe the behavior of the models and how to create those matrices that you describe above so that we could have rational debate about what a model run shows.

    Funny how drudge work actually produces real results, isn’t it?

  86. Peter H. says:

    So trees are sensitive to a few parts per million of CO2 only after 1950?

    If I had presented the ‘Hockey Stick’ graph in college I would have received an F.
    Splicing different data sets, i.e. proxy vs measured on the same graph is outrageous or dishonest at worst.

  87. P.G. Sharrow says:

    @Jeff Severinghaus;
    “Trees respire more at higher temperature, so they lose carbon when nights are warmer than average. So their ring width has not increased as much as it would have if the warming had been uniformly distributed over the diurnal cycle.”

    This is BS (bad science) All plants lose carbohydrates in cooling or colder conditions, more or less. Tree rings are a proxy for overall growing conditions. The soft thicker part is the “summer ” wood and the hard thin part the “winter” wood. Tropical woods have little or no rings.
    If the tree rings are thinner after the 1950s, then the growing conditions in that area have become less favorable. pg

  88. DocMartyn says:

    treegyn1, you missed something out. Trees are by nature, in the business of begetting more trees. One can spend ones wealth on horizontal and vertical growth, increasing ones resistance to storms and increasing total photosynthetic area.
    However, trees are long lived species and ‘know’ that generally the odd are poor that any but a tiny fraction of their seeds will make it into mature, fertile trees.
    In evolutionary terms, what should a mature, storm secure, tree do when the weather is optimal for seeds to grow?
    My guess is that trees sense and remember the past weather and then calculate which is the most appropriate balance of resources between seeds and growth.

  89. Steve Garcia says:

    @Peter H. 6:29 pm:

    If I had presented the ‘Hockey Stick’ graph in college I would have received an F.
    Splicing different data sets, i.e. proxy vs measured on the same graph is outrageous or dishonest at worst.

    Peter – I am no fan of the Team or Micheal Mann, but in attempting the goal of multi-century temperature records, there simply is no other choice but to splice together proxies and instrument data. I do give Mann due credit for attempting something on so vast a scale. In saying that it doesn’t mean I think he got it 100% right, and the MM2003 paper shows that he did not get it right.

    I think Mann – and anyone else who tries it – should present each proxy separately as fully as possible, then show how each proxy was homogenized to allow for merging the data, and, finally, to show the end result. Not only that, but each data set should have also been presented in its raw data stage and all adjustments applied should have been clearly labeled and explained. In this way any variations in the trends of each proxy would be clear to all who looked at the paper, and then everyone (most of all the authors) could peruse anomalous periods or trends for possible errors in methodology.

    What Mann basically did – transparency-wise – was to dump all the data into a black box, and then VIOLA! out came some numbers and graphs. And anyone trying to replicate had several layers of adustments, all of which were unidentified. In addition, the actual data used was not revealed, so we had a paper with a pretty picture, and none of what went in nor what happened inside the black box was revealed. It was Wizard of Oz shazzam-ship.

    That wouldn’t have been so bad, if he had kept good records of the data used and the methods applied, so that when others wanted to peruse it and possibly replicate all or parts, then he could have simply sent them a Zip file. As I understand it the journal’s rules required this, so it all should have not even had to involve Mann, anyway – only the journal.

    But as for merging proxies with instrument data – I do see it as necessary – if for no other reason than to show that in the overlap period the trends are the same (thus providing confidence in the other periods) and that the constants used to size the curves are correct.

  90. Philip Bradley says:

    which is corroborated by minimum temperature trends,

    since minimum temperatures usually occur at night

    No they don’t. They usually occur after dawn when solar insolation exceeds outgoing LWR.

    That a professor in a climate related discipline doesn’t know this is troubling.

  91. LKMiller says:

    DocMartyn says:
    November 29, 2011 at 7:20 pm

    treegyn1, you missed something out. Trees are by nature, in the business of begetting more trees. One can spend ones wealth on horizontal and vertical growth, increasing ones resistance to storms and increasing total photosynthetic area.
    However, trees are long lived species and ‘know’ that generally the odd are poor that any but a tiny fraction of their seeds will make it into mature, fertile trees.
    In evolutionary terms, what should a mature, storm secure, tree do when the weather is optimal for seeds to grow?
    My guess is that trees sense and remember the past weather and then calculate which is the most appropriate balance of resources between seeds and growth.

    Sorry Doc, but trees aren’t anthropomorphic. You are correct that the successful stands of trees that we see in natural forests are the result of successful sexual reproduction between the most genetically adapted individuals of the preceding generation. Thus, trees contain an extremely complex set of genes that allow such reproductive success under the widely ranging climatic and environmental conditions that occur on decades- and centuries-long time scales.

    Like many higher plants, those successful genotypes evolved the capability (necessity) to produce large numbers of seeds when they do flower because of the low success rate of seeds (it’s a cold cruel world out there). But, trees do not have brains and thus, do not “know” what they are doing. They possess the genetic capacity to respond to various environmental cues that stimulate flowering, the most common of which are abundant sunlight and drought.

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