by Dr Roger Pielke, Sr.
With the McShane and Wyler paper examining and questioning the method, this look at the proxy data and its problems seems like a relevant issue to review.
Comment On Tree Ring Proxy Data and Thermometer Type Surface Temperature Anomalies And Trends
There was an interesting conclusion in a New York Times article on the relationship between tree ring proxy temperature trend analyses and thermometer type measures of temperature anomalies and trends. The article is
British Panel Clears Scientists by Justin Gillis published on July 7, 2010
The relevant text is on page 2 it is written
“But they were dogged by a problem: Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries. If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.”
There are, however, problems with this conclusion. Since the thermometers are not coincident in location with the tree ring data (in the same local area), it would not be surprising that they are different. Indeed, this is yet another example that implies unresolved biases and uncertainties in the surface temperature thermometer type data as we discussed in several of our papers (see and see), as the thermometers are measuring elsewhere then where the proxy tree data is obtained. This obvious issue has been ignored in the assessment of this so-called divergence between the two methods to evaluate temperature anomalies and trends.
It is possible, of course, that the trees are responding differently due to the biogeochemical effect of added carbon dioxide and/or nitrogen deposition. Nonetheless, to accept the thermometer record as the more robust measurement of spatial representative temperatures is premature.
I have discussed this issue further in the posts
Comments On The Tree Ring Proxy and Thermometer Surface Temperature Trend Data
December 2007 Session ‘The “Divergence Problem’ In Northern Forests
It’s also possible the trees are not detectably responding to temperature at all.
Ian W says:
August 22, 2010 at 5:04 am
Medical science seems to be infected with similar problems (“Meta studies” for one). Take multiple studies with different parameters and small sample size and mash them together to get a result that is less than statistically significant, then publish that x is a cancer causing agent. Take mice/bacteria that have been bred to be cancer prone smear them with megadoses of a substance and pronounce the substance cancer causing when, surprise, you find cancer.
Makes sense to me, you definately have to show how, when and where all your measurements are made or else its useless. And your instruments calibration should be traceable to a certified procedure and standard.
Sam the Skeptic says:
“I’m well kitted-up in a kevlar suit and tin helmet before I say this but ….
Is there any mileage in the hypothesis that tree rings may well be a lousy proxy for temperatures but that they could be a fair proxy for climatic conditions in general?
Most people, certainly on the sceptical side of the argument, appear to believe that there is more to climate change than temperatures alone. If there is a “divergence” around 1960, why would that be? And would it tell us anything important about the current state of the planet?”
I would say that, yes, in general tree rings are probably a fair proxy for climatic conditions — for the suitability of the climate or that particular tree species. Unfortunately, trees have adapted and specialized over time. There are conifers which do best in cold climates, deciduous trees which do best in temperate, relatively damp climates, other species which do well in hot arid climates.
What is good for one species, may well be terrible for another.
It may be possible to look at species distributions and growth rates and make some generalized assessment of climate changes based upon that. So tree rings would be just one component in this evaluation.
That isn’t what they did. By a long way.
I find it absolutely amazing that people are still arguing about tree ring records of temperature as if they were the only measure of climate change. We can compare the validity of tree ring records not only with modern temperature measurements but also with a host of other temperature proxies. Fluctuations of glaciers and ice core isotope measurements are far better and a long list of other temperature proxies can also be used. So why this fixation on one tree-ring record? There are at least 3,000 scientific publications in the literature confirming the Medieval Warm Period and the Little Ice–can one tree ring record, flawed as it is, trump all of those? I think not! This very fact alone ought to be enough to show that Mann’s hockey stick is a joke. Even if it had been produced by ligitimate scientific methods, all it would show is that tree rings are not very good recorders of climate change because it is contrary to so much other, more accurate data. Let’s get over this tree ring nonsense and start using proxies that are much better.
Paul Coppin says:
August 22, 2010 at 4:15 am s
As a biologist, I will say for the umpteenth time, individual trees in the wild cannot be used for temperature proxies.
Right on Paul! As a Biologist I totally concur! It is a pleasure to be here, reading the comments of everyone who are not ‘elitist scientists’ who KNOW all the answers and have ‘drunk the cool-ade’ .
All the comments here so far are logical, and pervasive. Screw Trees as a proxy!
I was in the Cascades several years ago with a forrester working for a lumber company, collecting spruce branches for Christmas tree wreaths which he did as a ‘sideline’. He pointed out 12 Microclimates on one mountain ridge. We collected our boughs from a species which preferred high humidity and gathed from an area shrouded in fog almost all day. Move 1000 yards and the fog and that species disappeared!
Screw trees as a proxy! It doesn’t take Paul or I to see this logical point, as others have pointed out here!
Thanks Anthony for this wonderful forum, and asking questions with boldness!
The problem is that we scientists are dealing with Political Science which does not deal in logic and is not a science. Political Science deals in $ and Votes. Currently it is purchased by elitists!
Eric
I imagine it wouldn’t be hard to find thermometer to test the divergence, any thermometer should read OK as long as its inside GISS’s 1200Km radius. 🙂
I concur with some other posters that if the tree ring proxy doesn’t agree with the thermometers after 1960 then the proxy cannot be used for temperatures before 1960 until the cause of the divergence is known. That’s just good science.
What tree rings DO show is a robust character to temperature changes, taking advantage when conditions are good, and closing in when conditions are not.
Many multiple specie tree stands develop robust responses to stress, which is why attempts to put out all fires, planting single species forests, and bug spraying may harm that very ability.
I am reminded of the lessons learned at Yellow Stone. While attempts were underway to stem the fires, they raged unopposed. When the fires were contained and eventually put out, all kinds of things were learned about how the forest and fire relationship turned out to be beneficial.
So the behavior of flora and fauna to stress and good times is a measure of the flora and fauna’s natural internal resources to survive, not the conditions surrounding it. And maybe that is the most important lesson to learn. The relatively mild stress of positive temperature changes, and the weather pattern variations that come with that (IF they do), will be rather easily handled by this Earth.
This quote is interesting. How does the divergence problem stand up against satellite temperature, rather than surface temperature? I assume the former does not exhibit some of the “adjustment” problems the latter suffers from.
Paul Coppin’s post on the whole subject of the futility of using tree rings for temperature proxies is right on the mark.
In a previous comment from a forester on the subject from another post some months ago it was stated that young trees in a forest grow very slowly due to lack of sunlight until older trees around them either die or are felled by storms, then they grow like crazy. Therefore not only must you have a significantly statistical sample of trees from a given forest, you must also have a significantly statistical sample of site conditions from that forest which include the history of neighboring trees, position in the forest, etc. It would take a knowledgeable forester teamed with an expert statistician to make such a study of a given forest. Even then you would only understand the history of the local region the forest was in.
Are there any published papers from biologists (or foresters, for that matter) that prove that? If not, for the sake of our future, some responsible forest knowledgeable biologist should do so and then get that information to the public in some manner before we legislate our way to oblivion.
If tree ring proxys from 1960 on give lower temperatures than thermometer readings it is clear that the cause of those low readings is not temperature variation. Since an unknown agent is now revealed to be present in proxy temperature measurements and since we do not know what it is all proxy measurements become suspect and should be discarded until this unknown agent is discovered and its role explained. But this is not what they did. They had a massive dataset, part of which they did not like, so they simply threw out the offending data. In science you are not allowed to arbitrarily throw out data and then substitute other data that you do like but this is what they did. It so happens that the temperature data they added included two decades of the “late twentieth century warming” which I have proven to be falsified and non-existent. The correct response would have been to declare all conclusions drawn from that collection of proxys invalid, including the entire hockey stick project. It is based upon a hypothesis that tree rings can tell temperature that has been proven to be false from their own data. To suppress key data that proves your hypothesis wrong is known as scientific fraud and they should have been brought up on charges of fraud instead of being officially whitewashed. That same gang did not hesitate to accuse Bjorn Lomborg of scientific fraud when they did not like his book “Skeptical Environmentalist.” Lomborg did not even deny warming, just urged moderation and common sense in dealing with it.
The most recent climate science work has focused on paleoclimatic archeological investigations in colonial plantations. It turns out that the divergence problem can be eliminated, vindicating the hockey stick, by reading tea leaves.
Divergence.
I liked the pic and title in the post alluding to Robert Frost’s poem:
John
” Mike McMillan says:
August 21, 2010 at 10:44 pm
I fail to understand the great faith in tree rings as temperature proxies. Trees do better in warm years than in cool years. Trees do better in wet years than dry years”
Do they? There is a relationship between longevity and fecundity in most species. You can invest in yourself (longevity) or invest in offspring (fecundity). The growth of a tree, in the form of a tree ring, is an investment in self; big trees have a bigger canopy absorb more sunlight and can have more progenitor sites.
Allow me to anthropomorphize; I am a tree, I have a ‘memory’ of the last few years weather conditions (information storage is trivial biologically), this year I can make a choice in spending my energy budget between longevity and fecundity.
My first priority is to survive until next year, so a minimum 30% goes on housekeeping (tree rings), now my decision to produce seeds will be based on my history and memory of the previous seasons.
If the last few years have offered ‘ideal’ conditions for my seeds to have a chance, it would make sense that I would increase my allocation of resources towards fecundity and away from longevity. In bad years, the investment decision is reversed; cut down on investment in fruiting bodies and concentrate on making myself a bigger canopy and root system.
So the distribution of tree ring widths should not be ‘normal’, but be the same size or thinner in ‘good years’ compared with ‘moderate years’.
I have seen no evidence that temperature, one of the least important viable for plant growth, should track growth.
One would probably see the relationship between temperature and tree ring data much better if, instead of average temperature to tree ring anomaly, one compared (max-min) + precipitation to tree ring anomaly.
Just because Mann installed the basement stairs in the attic doesn’t mean that basement stairs are useless.
@ur momisugly Anna V
Proper thermometers are not calibrated against ice and boiling water. They are calibrated against reference thermometers which are in turn calibrated against more accurate themometers in a chain of traceabilty back to a Reference Standard based on the triple point of water being exactly 273.16 kelvin. (This defininition is due to change next year with the kelvin being defined in terms of the Stefan-Boltzman equation).
Having said that, i agree, all temperature measuring devices, be they mercury in glass thermometers, thermocouples, pyrometers or even tree rings have a working range and must stay in agreement with the reference within that range. It is obvious that at current tempertures the trees used in MBH98 etc are outside their working range and that if such temperatures occured in the past then it is higly likely that they did not record such tempertures correctly.
Another problem mentioned. From 1960 on, CO2 concentrations have been steadily increasing (at an alarming and unprededented rated – sorry, couldn’t resist!) providing trees more of the basic ingredient they require for photosynthesis and growth. Yet they demonstrate reduced growth rates which have been interpreted as cooling temperatures. With higher temperatures and more CO2 in the atmosphere, trees should be indicating faster rising temperatures than thermometer, not declining temperatures. If they have been so far wrong since 1960 to the present, why should we have any confidence in tree ring data as a temperature proxy prior to thermometer records? Who knows how many other times the teee ring data diverged from temperature for the same reason, yet unknown, as they have since 1960. This whole approach to temperature reconstruction should be taken with a grain of salt, it is dubious at best!
Bill Yarber
Ref – Gerry says:
August 22, 2010 at 6:08 am
“From an earlier article: “Ultimately, any alternative explanation must fit all the observations. If the alternative hypothesis fails even only one of the observations, then the alternative is rejected.” (Ferdinand Engelbeen) Ok, tree rings as a temperature proxy, rejected.”
___________________________
How about tree rings as a climate proxy? Here’s what I was thinking: Ya take the diameter of the tree and divide by the total number of rings and this gives ya the average growth per year, then ya go looking for rings that are bigger than average and ya count them as good years. Of course, the rings that don’t come up to average they’s the bad years. Now we all know that good years are nice and bad years ain’t. That’d work, right?
So basically, the priciple of uniformitarianism would say that if tree rings cannot tell temperature in the present, then they couldn’t tell it in the past.
“Since around 1960, for mysterious reasons, trees have stopped responding to temperature increases in the same way they apparently did in previous centuries. If plotted on a chart, tree rings from 1960 forward appear to show declining temperatures, something that scientists know from thermometer readings is not accurate.” And tree rings were used to construct the hockey stick. Apparently these people believed that if you don’t like some of the data you collected you can throw it out and substitute other data that you do like. That was the trick to “hide the decline.” I have news for you guys: if you are a scientist you are not allowed to do this. If that part of your dataset which you can independently evaluate is defective for unknown reasons there is absolutely no way to know if those parts of your dataset that cannot be independently evaluated are free of this defect. The entire dataset is made worthless because of this and conclusions drawn from it, such as the existence of a hockey stick, must be abandoned. But this is not what we see. Instead of discarding the dataset the offending data are thrown out and data that conforms to their prejudicial judgment is grafted onto it. And it is that data graft that supplies the high point of the hockey stick we are shown. Quite a trick indeed, needed to hide the decline from proxies. It so happens that a twenty year stretch of that data graft includes the so-called “late twentieth century warming” which I have proven to be fake and which is non-existent. Throwing out undesirable data and importing data that conforms to your prejudice is called scientific fraud. They should have brought him up on charges of scientific fraud instead of whitewashing him. Perhaps another group can institute that charge that the officials chose to ignore. When Bjorn Lomborg came out with his book “Skeptical Environmentalist” the warmist clicque immediately accused him of fraud to a Danish committee against scientific fraud. And he did not even deny warming, just urged moderation and common sense in dealing with it.
My comments are disappearing into a black hole. What is going on?
[Reply: for some reason WordPress was putting them in the Spam folder. Rescued & posted now. ~dbs, mod.]
@Paul Coppin
Sometimes tree rings correlate very well with recorded temperatures over a long time period.
If you reconstruct temperatures you need many different proxies, and also tree rings.
I believe that the MWP was as warm as the actual warm period in Europe. And I don’t understand why there is no progress in tree ring – climate science.
But you MUST also use tree rings for climate reconstructions.
So, determining a single variable within a multi-variable situation when you have no idea how to weight the other variables, much less the first clue about their values, differs from spilling the guts of a chicken to determine what the next fashion trend on the runways of Milan and Paris how, exactly?
Please use small words. I’m a bit slow, and obviously unimaginative enough to grasp the nuance of the truths I’m to be enlightened with.
And is it just me, but why wasn’t this a much better indicator that Mann is a garden variety snake oil charlatan than any dissection of deviously written crappy computer code to a lot of other folks, as well?
Buntgen et al. 2008 uses trees that dont diverge until 2003 (follow warming extremely well) so I think you should point out that trees are responding differently in different places.
Let’s hope veggie gardens in Central Oregon have traditional plants rated for its tough climate zone instead of the “Earth is warming” brands. Further more, this pressure system sets itself up for dry, dry, drought conditions (warm and dry during the day, falling to cold and dry at night), demonstrating that cold trends are what brings drought, not hot trends. For those gardeners who have little knowledge of history, their gardens filled with cantaloupe and grapes along with other warming Earth types of fruits and veggies, will be in for a rude awakening.
URGENT – WEATHER MESSAGE
NATIONAL WEATHER SERVICE MEDFORD OR
229 AM PDT SUN AUG 22 2010
…FROST EXPECTED MONDAY MORNING…
.A COLD UPPER LEVEL TROUGH IS EXPECTED TO LEAVE DRY AIR AND
MOSTLY CLEAR SKIES IN ITS WAKE SUNDAY NIGHT. BY EARLY MONDAY
MORNING TEMPERATURES ARE EXPECTED TO FALL LOW ENOUGH FOR AREAS OF
FROST TO FORM.
ORZ030-222300-
/O.UPG.KMFR.FZ.A.0007.100823T0900Z-100823T1500Z/
/O.NEW.KMFR.FR.Y.0019.100823T0900Z-100823T1600Z/
NORTHERN AND EASTERN KLAMATH COUNTY AND WESTERN LAKE COUNTY-
INCLUDING THE CITIES OF…BEATTY…BLY…CHEMULT…CRESCENT…
GILCHRIST…SPRAGUE RIVER
229 AM PDT SUN AUG 22 2010
…FROST ADVISORY IN EFFECT FROM 2 AM TO 9 AM PDT MONDAY…
THE NATIONAL WEATHER SERVICE IN MEDFORD HAS ISSUED A FROST
ADVISORY…WHICH IS IN EFFECT FROM 2 AM TO 9 AM PDT MONDAY. THE
FREEZE WATCH IS NO LONGER IN EFFECT.
* TEMPERATURE: TEMPERATURES WILL FALL TO BETWEEN 32 AND 36 DEGREES
FAHRENHEIT FOR 3 HOURS OR MORE AT MOST LOCATIONS. A FEW ISOLATED
AREAS…PARTICULARLY IN AND AROUND CHEMULT AND NEAR AND AROUND
CHILOQUIN…WILL EXPERIENCE LOCALIZED FREEZING CONDITIONS AS
TEMPERATURES FALL INTO THE UPPER 20S TO LOWER 30S.
* IMPACTS: AREAS OF FROST WILL FORM EARLY MONDAY MORNING.
VEGETATION SENSITIVE TO COLD TEMPERATURES AND FROST IS LIKELY
TO BE DAMAGED OR KILLED.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
A FROST ADVISORY MEANS THAT FROST IS EXPECTED. SENSITIVE OUTDOOR
PLANTS MAY BE KILLED IF LEFT UNCOVERED.
&&
$$
BTL