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
For all the ills of being poorly correlated to temperature, tree rings studies in places like the Pacific Northwest, where some species go back 2,000 years, events such as the Roman Warm period, MWP and Little Ice Ages are well depicted. They also show off Super El Ninos, putting 1998 in it’s place…down the list.
Oops, sorry, the above tree ring data series was done by Cook. Couple of nice videos of each year plus a comparison with temp data.
Today’s rough climate is tame by comparison to events of the last 2000 years.
My goodness – trees arn’t thermometers – except for those that show a hockey stick shape.
Why look at the trees being the problem, couldn’t it be the thermometers’ fault?
Maybe since the 1960s thermometers have been giving inaccurate readings of temperatures, after all the tree ring based temperature record is 1500 years long and only had a problem in the last 50 years (about 3% of the record) while the thermometer based temperature record is only about 150 years long so a whole 1/3rd of that record doesn’t match the tree ring record. Overall it seems more reasonable to assume that thermometers are just a poor means of measuring temperature thus the unreliable thermometer data should be thrown out in favor of the tree ring data.
There is a saying, “putting the cart before the horse”.
Climatology is full of examples.
It seems that they have not heard of the word “calibration”. All thermometers are proxies of the temperature T which enters into equations. ALL
Some are more accurate proxies than others.
Take a mercury thermometer, and calibrate it the standard way : 0 at ice melting point and 100 at water boiling point at 1 atmosphere. That is the Celcius scale, and can be very accurate.
One now has a thermometer to calibrate against for less accurate proxies.
The scientific method for calibrating tree ring width to be used as a thermometer would require a statistically significant sample of tree samples from a region where there are thermometer readings for a number of years.
Where is this calibration curve?
The defect of the tree ring studies is not only that they compare the tree proxy temperatures to average globe temperatures, but that they have not demonstrated a calibration curve .
Putting the horse in front of the cart the fact that there is a decline after 1960, according to the logic of the anomalies, should have shown a decline in the more accurate thermometer readings. The decline in the tree ring proxy data demonstrates that the tree rings are not thermometers.
“…trees have stopped responding to temperature increases in the same way they apparently did in previous centuries…”
No they did not respond that way for “centuries” . Temperature records started only around 1850, and divergence problems before that period may have been just as common as they have been after 1960.
The best answer is still that tree rings are very poor temperature proxies.
The second best answer is that temperature records may be corrupt as well.
But Gillis’ assumption that tree rings responded to temperature variations for a thousand years and then in 1960 suddenly atopped to do so is embarrassing junk.
It really is very simple.
If you “lose temperature sentativity” after a certain date, you cannot under any circumstances be certain that it EVER had ANY temperature sensativity to begin with. I do not understand why that is so difficult to understand.
Trees make horrid thermometers.
I’m well kitted-up in a kevlar suit and tin helmet before I say this but ….
Is there any mileage in the hypothesis that tree rings may well be a lousy proxy for temperatures but that they could be a fair proxy for climatic conditions in general?
Most people, certainly on the sceptical side of the argument, appear to believe that there is more to climate change than temperatures alone. If there is a “divergence” around 1960, why would that be? And would it tell us anything important about the current state of the planet?
I only asked … 🙁
As a biologist, I will say for the umpteenth time, individual trees in the wild cannot be used for temperature proxies. Even a first year biology student, with a little reflection, can explain why. The short answer is that every tree grows in a unique ecology, sufficiently different from its neighbour to render the proxy data unquantifiable for small populations. A sufficiently large population of tree samples can point to gross local events such as large scale fires, droughts or similar events, but to look at climatic variables you have to look at forests, not trees.
This underpins the entire problem with using complex organisms as proxies for anything. Their inherent adaptability makes them unfit for the role. Its not until you can begin to evaluate the response of the population can you begin to approach any kind of statistical significance to certain measured results, and even then, with great risk. Complex biological systems are inherently chaotic. Identifying confounding variables is often a bigger problem then accurately measuring certain parameters. Complex organisms and their behavior is the result of a bewildering number of multi-causal, multi-variable effects.
From my very first year uni programs, its been clear that the physical sciences pursued by my student colleagues have always had a poor scientific appreciation of the nature and complexity of biological systems (aided, I suppose, by the late night beer sessions explaining to my engineering buddies just how it was their girlfriend got pregnant…). Mostly I chalked this up to significant lack of training in the biological sciences as they pursued their interest in the relatively simplistic (if not indeed, simple) narrow world of physical and mathematical problems. The result is the kind of worthless science produced by the current crop of “climate scientists”, which is at best , simply intellectually naive, and at worst, dangerously agendized. It pains me to see colleagues climbing on the agenda bandwagon promoting the thin-on-the-ground attitudinal bio-proxy science that is turning up. Science education is, I believe, in crisis. Not only so in the agendas that drive much of it, but in the fundamental training biology students are receiving – they simply are not getting an adequate foundational basis on what life is, a knowledge that comes from things like the “old” disciplines of comparative anatomy, phylogenetic analysis, physiology etc.
In order to model anything, you first have to know what it is you are modeling. I believe science education has failed miserably in preparing students how to come to know about what they are doing, preferring instead to dazzle them with the bright lights of technology, rather then the bright spark of intellectual realization. The end result is the present morass of intellectual fluff being posited as grand revelations on the future of the planet.
Hi there!
Well I wonder why a layman as me react to the most obvious basic contradictions
in cliamate proxies.For six month I wonder what the climatehistory would look with out tree ring proxies removed. What does the hockeystick and all the climatic conclusions look like without them? For me this is defenitely a “its much vorse than I thought” that this obvious circumstances doesnt hit the table until now!
Proxies are theories for replacement of missing data that cannot be recovered by the past as measurements were not available.
Widely used by scientists and a good source of funding to continue the theoretical area.
The idea about treemometers is that only trees which are growing in certain limited an more or less stable conditions may respond predominantly to temperature as a main factor. The bristlecones are constantly water and nutrient-limited, the Siberian trees have a constant abundance of water (no limit there) but their growth occurs only during one month in summer.
BTW – the Russians, when they write themselves about their tree rings, are very careful to point out, that the trees are a proxy for summer Siberian temperature. Not much talk about global temp here…
My simple point has always been to point at the elephant in the room.
If tree ring data was adequate prior to 1960 then why are they not adequate after 1960? [diverged from thermometer data]. Fine, so what degree of confidence should I have on tree ring data prior to 1960?
In my simple mind one of the measurements is most likely producing erroneous data. UHI, “biogeochemical effect of added carbon dioxide and/or nitrogen deposition” and geographic locations only complicates matters further.
Botanists have told climatologists that tree growth is not dependent on temperature so the use of tree rings as temperature proxies is unsound.
Statisticians have told climatologists that their use of statistics is flawed both in methodology and sample sizes.
Yet climatologists continue despite this expert advice to use tree ring temperature proxies and flawed statistics based on insignificant samples to support wild unvalidated claims.
Is there any other branch of science where these behaviors would be accepted?
Hmmmm
Just being a Simple Red Neck, I am easily puzzled.
If you have one set of temperature records taken in old growth forests (I.e. tree ring proxies).
And a second set of temperatures taken in areas that have, over the years, become Urban Heat Islands.
And you then compare them.
Why in the world would you expect them to match?
Befuddled in Texas,
Steamboat Jack (Jon Jewett’s evil twin)
Bad news for Mann and Briffa. We just aren’t into the tree ring readings.
So let’s start with the hypothesis that trees are really better thermometers than thermometers. Now someone has to explain the following to me:
My mother has 2 red maple trees in her yard. They were the same size when they were purchased at the same nursery and planted 20 feet apart about 10 years ago. Today one is twice the diameter of the other and the larger one is nearly 3 times as tall.
Which one is the better thermometer? Why?
PS The real reason one is bigger than the other is because the biggest one was planted where the old outhouse used to be, and the smallest one wasn’t.
It is my understanding with wide enough error bars anything can be a thermometer.
Scroll down to page 18 (of the pdf file) and take a look at the symmetry of the bristle cone pine and strip bark juniper which Mann used to create his proxies. Does anyone know what kind of tree Mann is holding in his glamor shot?
Yes, this is a tree you can trust!
oops, here is McIntyre’s file referred to above. How it all started.
Trees like CO2 rather a lot.
I thought trees responded rather well to increased levels of CO2, that should mean that trees should show greater growth since 1960 not less, OR DO THEY.
http://en.mercopress.com/2010/02/08/climate-change-and-higher-levels-of-c02-making-trees-grow-faster
The Parker and McMahon’s paper focuses on the drivers of the accelerated tree growth. The chief culprit appears to be climate change, more specifically, the rising levels of atmospheric CO2, higher temperatures and longer growing seasons.
During the past 22 years CO2 levels at SERC have risen 12%, the mean temperature has increased by nearly three-tenths of a degree and the growing season has lengthened by 7.8 days. The trees now have more CO2 and an extra week to put on weight. Parker and McMahon suggest that a combination of these three factors has caused the forest’s accelerated biomass gain.
From an earlier article:
“Ultimately, any alternative explanation must fit all the observations. If the alternative hypothesis fails even only one of the observations, then the alternative is rejected.” Ferdinand Engelbeen
Ok, tree rings as a temperature proxy, rejected.
Gerry
tree rings for Age of the tree, fine.
for wet or dry seasons, fine.
for fires, fine,
for bugs, fungi,pollen, soil type and nutrition of soils, fine
for the immediate surrounding area only, fine
for temp?
no way!
What do you think would be more consistent over the centuries?
1. Trees in forests
2. Thermometers in villages and at airports
The NY Times blindly accepts that #2 is more accurate gauge of temperature. Most objective observers would consider the possibility that the thermometers were measuring increased heat produced by human development.
trees do not grow at -40C
trees do not grow at +100C
trees grow very well at 15C
This cap shape must have a dependence on temperature. It may not be linear but it must be there.
Somewhere between 15C and 100C the growth must start declining Did trees pass the optimum in the 60s?
Uncontrolled emissions in the 60s, 70s and 80s was known to cause acid rain (to an extent that some countries were forced to add lime to lakes to prevent damage) there was plenty of evidence that trees were being damage also.
Is it not true to say Damaged trees=slow growth
There are many factors that can slow tree growth but apart from over temperature these effects will be diminished by limited industrialisation (before 1900?).
Trees are rubbish thermometers, but in all the noise there MUST be a temperature signal. A large local sample will lower the noise from sickness, or damage. A large global sample will lower the noise from changes in soil fertility, etc.
Nothing will remove the noise from CO2 fertilisation, or other global events.
Some trees growing at the limit of their water needs may be negatively affected by rises in temperatures from their minimum growing value – growing in heat requires more water. these will always show a negative growth increase with temp. But if averaged with enough positive responders then these will be insignificant.
But the signal that remains must, when averaged contain a temperature signal (not necessarily linear)
wiki:
“Overall, the Program’s cap and trade program has been successful in achieving its goals. Since the 1990s, SO2 emissions have dropped 40%, and according to the Pacific Research Institute, acid rain levels have dropped 65% since 1976.[16][17] However, this was significantly less successful than conventional regulation in the European Union, which saw a decrease of over 70% in SO2 emissions during the same time period.[18]
In 2007, total SO2 emissions were 8.9 million tons, achieving the program’s long term goal ahead of the 2010 statutory deadline.[19]
The EPA estimates that by 2010, the overall costs of complying with the program for businesses and consumers will be $1 billion to $2 billion a year, only one fourth of what was originally predicted.[16]”
“However, the issue of acid rain first came to the attention of the international community in the late 1960s, having been identified in certain areas of southern Scandinavia, where it was damaging forests. The matter quickly became an international issue when it was discovered that the acid deposits in these areas were a result of heavy pollution in the UK and other parts of northern Europe.
http://www.politics.co.uk/briefings-guides/issue-briefs/environment-and-rural-affairs/acid-rain-$366677.htm
Acid rain and air pollution emerged from the industrial boom of the early 1900s onwards and the increasing levels of chemical production associated with these processes. The building of taller industrial chimneys from the 1960s onwards was largely held to be responsible for pollutants generated in the UK blowing as far as Scandinavia. “