A new paper in GRL published Sep 6th Secular temperature trends for the southern Rocky Mountains over the last five centuries makes use of some tree core sample data gathered by Steve McIntyre and Mr. Pete. Readers of WUWT and Climate Audit may recall that in the summer of 2007, Steve left CA in my attendance for a couple of weeks while he went to Colorado to visit his sister, and to prove or disprove his ‘Starbucks hypothesis’ which asks:
…could a climate scientist have a Starbucks in the morning, collect tree rings through the day and still be home for dinner?
This came about because apparently RealClimateScientists™ don’t have the funds or time to get out of the office and gather new tree core samples, such as cores that would fill in the last 25 years that seems to be part of that “tricky” divergence problem. In A Little Secret (Oct 2007) Steve wrote:
Don’t you think that someone on the Team might have been a little curious as to what bristlecone ring widths have done during the past 25 years? For this, we have the classic excuse of Michael Mann and the Team for not updating bristlecone and proxy records is that it’s not practical within the limited climate budgets:
While paleoclimatologists are attempting to update many important proxy records to the present, this is a costly, and labor-intensive activity, often requiring expensive field campaigns that involve traveling with heavy equipment to difficult-to-reach locations (such as high-elevation or remote polar sites). For historical reasons, many of the important records were obtained in the 1970s and 1980s and have yet to be updated.
This new paper proves that you can do field science on vacation, while visiting Starbucks, and in a single day. It also has a thing or two to tell us about the accuracy of tree ring width and wood density records and their value as a temperature proxy.
First, the calibration of the d18Oc data with instrumental temperature data from the nearby Cheesman USHCN station.
Abstract:
Pre-instrumental surface temperature variability in the Southwestern United States has traditionally been reconstructed using variations in the annual ring widths of high altitude trees that live near a growth-limiting isotherm. A number of studies have suggested that the response of some trees to temperature variations is non-stationary, warranting the development of alternative approaches towards reconstructing past regional temperature variability. Here we present a five-century temperature reconstruction for a high altitude site in the Rocky Mountains derived from the oxygen isotopic composition of cellulose (d18Oc) from Bristlecone Pine trees. The record is independent of the co-located growth-based reconstruction while providing the same temporal resolution and absolute age constraints. The empirical correlation between d18Oc and instrumental temperatures is used to produce a temperature transfer function. A forward-model for cellulose isotope variations, driven by meteorological data and output from an isotope-enabled General Circulation Model, is used to evaluate the processes that propagate the temperature signal to the proxy. The cellulose record documents persistent multidecadal variations in d18Oc that are attributable to temperature shifts on the order of 1C but no sustained monotonic rise in temperature or a step-like increase since the late 19th century. The isotope-based temperature history is consistent with both regional wood density-based temperature estimates and some sparse early instrumental records.
Berkelhammer, M.,and L. D. Stott (2012), Secular temperature trends for the southern Rocky Mountains over the last five centuries, Geophys. Res. Lett., 39, L17701, doi:10.1029/2012GL052447.
During the 20th century, the summer surface temperatures in this region are characterized by a broadly parabolic trend, with minima during the 1930s and early 1980s
and a period of relative warmth during the late 1940s to early 1960s (Figure 1). The temperature reconstruction based on d18Oc suggests that in terms of mean temperature and multidecadal variance, the 20th century is largely comparable to
the preceding 4 centuries (Figure 3).
Despite the seemingly good correspondence between tree ring width (Figures 3 and S5) and d18Oc proxies during the instrumental period, over much of the previous 400 years
the two records exhibit very different climate histories (Figure 3). Prior to the mid 19th century the width-based reconstruction indicates temperatures at this site were
approximately 0.7C cooler than during the instrumental era while the d18Oc reconstruction suggests that temperatures have remained stable. The residual between these two reconstructions (Figure 3) is sufficiently large and sustained to suggest the existence of a significant bias in one or both of these two proxies that cannot likely be explained as arising simply from random errors in the linear transfer function.
Daux et al. [2011] also note an apparent divergence between width and isotope based temperature reconstructions in Larix decidua from France. They attribute the divergence
possibly to changes in the soil hydrology (i.e., plant utilization of soil water enriched by evaporation) or moisture stress. At this site, soils are thin and the trees are characteristically shallow-rooted and it is thus unlikely that deeper, low-residence time water would be available. Further no indication of anomalous 20th water stress or abundance is seen in either d13C from pinyon pine trees across the region [Leavitt et al., 2007] or widths from lower elevation drought-stressed trees [Cook et al., 1999].
To help resolve this enigma, an additional temperature proxy that is based on a regional composite of wood density measurements is considered [Briffa et al., 1992] (Figures 3 and S5). This temperature proxy is independent of both tree growth rate and the isotopic composition of cellulose and is shown to have high skill as a growing season temperature proxy in this region (Figure S5). To test the consistency between density and isotope-derived temperatures we look at the cross-wavelet [Grinsted et al., 2004] between the records (Figure S6). In the multi-decadal window, the density and isotope reconstructions are consistently in-phase with one another through the last 400 years, implying that the two proxies are likely being influenced by a common climate parameter, which we assume to be growing season surface temperature variations. With respect to the cross-wavelet between widths and isotopes, the two appear to only be commonly forced during the 20th century (Figure S6).
Further confirmation of this is garnered by looking at early instrumental data from the region (not shown), which indicate that surface temperatures between 1850–1870 were, on average, as warm as those of the 1930s–1960s [Wahl and Lawson, 1970], which is consistent with the relative thermal stability implied by the isotopic and
density reconstructions. Taken together, the d18Oc and wood density records provide a fairly consistent perspective on multidecadal temperature variations, which suggest a cool bias in the width-based temperatures prior to the mid 19th century.
Conclusions
The isotope temperature record from this site indicates relatively stable summer season temperatures amidst decadal to multidecadal temperature fluctuations. Although
the isotope reconstruction is associated with several significant sources of uncertainty that arise from the transfer function and tree-to-tree heterogeneity, the results highlight the need for, 1) additional efforts to extend a processbased network of temperature reconstructions across the region and 2) develop pre-instrumental forward model simulations (for both widths and isotopes) that could be used to test the assumptions of linearity that underlie the proxy reconstructions.
The main points of the paper are:
- Temp. trends in the SW US can be reconstructed using isotopes in tree rings
- A process model of the proxy can be used to characterize uncertainty in proxy
- Temperature trends in SW US have been relatively stable over last 5 centuries
Acknowledgments. The authors thank M. Zhu, G. Kleber and
M. Rincon for invaluable assistance in sample preparation and analysis;
Z. Gedalof and J. Franks for cross dating the samples used in this analysis;
V. Bommarito, L. Holzmann, P. Holzmann, R. Lee, N. McIntyre S.
McIntyre, L. Thomas for sample collection; A. Ballantyne for feedback
on an earlier version of the paper; K. Yoshimura for providing outputs
from the IsoGSM simulations; 2 anonymous reviewers for suggestions
on improving the manuscript and the ITRDB for tree ring data. Funding
was provided by NOAA Award NA10OAR4310129 to LDS.
This effort, peer reviewed paper, and results just goes to show that citizen science can do what RealClimateScientists™ can’t or won’t, and do it just as effectively. For those who worry about such things, it should be noted that Steve applied for, and got permission for the core sampling of the Bristlecone pines in Colorado.
h/t to Dr. Leif Svalgaard who has the full paper on his website: http://www.leif.org//EOS/2012GL052447.pdf
Anthony says: “Maybe WUWT needs to launch a Yamal expedition.”
I agree, but under the management/control of an impeccably neutral technical/scientific authority.
Let’s bury the Holy Hockey Stick once and for all.
I think you will find a lot of people prepared to fund such a exhibition and demonstrate Mann’s deception and fraud beyond all reasonable doubt.
Anthony Watts says:
September 11, 2012 at 10:39 am
Maybe WUWT needs to launch a Yamal expedition.
We allocated some time from our Eastern Sierra Trout fishing expedition this past July, and spent a couple of hours at Sheep Mountain/Patriarch Grove. I managed to catalog about twenty tagged trees (one or two trees provided a bit of a mystery), but due to time constraints I couldn’t delve in to the Graybill Bristlecones. I plan on returning next year. This might be a bit more plausible than a Yamal expedition. The Sheep Mountain area is approx. 39 mile NE of Big Pine via highway 168, the last 20 miles or so being a steep and windy dirt road, but drivable. Anyone up for it?
Perhaps the Little Ice Age doesn’t show in the rings of these bristlecones, but, as I recall, it does show in the altitude the trees grow at. There are dead bristlecones still standing, at an altitude above this grove.
I’m not sure if they died at the close of the MWP, or some earlier climate optimum. However they are there.
tonyb says:
September 11, 2012 at 9:55 am
…… many LIA summers were as hot as today. It is the winters and nights that have got warmer in recent centuries.
tonyb
Hi Tony
See my comment re Steven Mosher’s
You know you can trust these people by their shoes.
Anthony Watts
Yes to a WUWT bristlecone expedition. Also an expedition following Hanibals route over the Alps which were less glaciated and more accessible in Roman times and yes to an expedition to Greenland. (not that you mentioned the last two of course)
tonyb
And this study shows that trees don’t make good thermometers?
>>>RHS says:
September 11, 2012 at 9:05 am
One question about the Cheesman USHCN station. How well situated is the site considered?
From the image here: http://gallery.surfacestations.org/main.php?g2_itemId=50424
It looks like a typical mountain setting with a low tree density.
>>>It’s the best of the USHCN sites along the Front Range. Boulder’s site has a checkered siting history, and Fort Collins was set up on a farm plot which now harbors a bus station within the city.
Cheesman itself isn’t the best rural site – note that it’s right next to the reservoir, with variable distance from the water line.
It’s good that the data analysis ends around 2002, which was the year of a traumatic event for that area – the Hayman fire, largest in Colorado’s recent history in acreage, which denuded close to 100 square miles and coming within 1000 feet of the station. Temperatures at the site have run quite a bit higher since then, and I’m sure were very high the week of the fire (although the observers were wisely evacuated). That fire generated a spectacular orange supercell firestorm that I was watching warily from my home (and co-op station) 40 miles to the north.
Steve… If you want to do some dendro studies near my place, I have good records back to 1982 and there’s bristlecones not far from my home/coop site (Coal Creek Canyon). I also have an increment borer, and need to learn how to use it!
tonyb says:
September 11, 2012 at 12:25 pm
yes to an expedition to Greenland
Hi Tony, worth a visit, but when I was there, they just were experimenting with planting several kinds of trees in the far southern part. For the rest I haven’t seen one tree there… And no Starbucks.
Figure 3 is damning for paleoclimatology. It shows three widely accepted techniques for interpreting tree ring wood as a proxy for temperature. It demonstrates that trees are useless as temperature proxies for anything other than qualitative impressions.
Reading any meaning into fractions of a degree centuries ago based on tree ring proxies is climate Rorschachism..
I think expert in tree physiology, wood anatomy and plant cell biology Prof. Rod Savidge sums it up well in his email-
“ClimateGate Email 1738
“However, there are bounds to dendrochronology, as there are to every field of investigation, and the discipline has spilled over way outside of those bounds, to the point of absurdity.”
“What troubles me even more than the inexactness attending chronological estimates is how much absolute nonsense — really nothing but imaginative speculation — about the environment of the past is being deduced from tree rings and published in dendrochronology journals.”
Correction…
The Hayman fire was 216 square miles.
RHS: One question about the Cheesman USHCN station. How well situated is the site considered?
I believe what you are looking at in the overhead views is an out-of-service Stevenson screen. The ranger I talked to this July thought it was replaced by the MMTS in 2000. The current instrument is a few feet southeast at 39.220166, -105.278233. Sorry, I’ve been slow in posting a writeup of my visit. The site seems to have the normal anomalies in NOAA’s reporting of history: Their location reports would have put it into the water well out in the reservoir during one time period. I haven’t had time to try to shake it down. Would be really helpful if we could get access to the B44’s without an act of Congress.
I suspect the site has not actually been moved since its creation. Your remarks seem to me to be valid, but I don’t evaluate these things, I just take pictures. : > )
I
Leif Svalgaard says:
September 11, 2012 at 10:13 am
John W says:
September 11, 2012 at 10:05 am
Are you saying that it did not happen?
Not necessarily, just introducing some caution in interpreting proxies. Of course, when the proxies confirm one’s pet theory they are good, right? And when not, they are bad [or other effects corrupt the data], right?
———
Yes, I saw that in the debate with the Stanford study of Organic nutrition. Saying that Organics have the same nutritional value as non-organic foods.
chris y says:
September 11, 2012 at 1:07 pm
Figure 3 is damning for paleoclimatology. It shows three widely accepted techniques for interpreting tree ring wood as a proxy for temperature. It demonstrates that trees are useless as temperature proxies for anything other than qualitative impressions.
Using the 18O isotope as the indicator is independent of the material being wood. The isotope method woks with any material containing oxygen: chalk, wood, ice, whatever. So [and that is the main point of the paper], the first graph should be fine.
Is it me or do I see a negative temp trend starting in the early 1950’s to present day?
Leif and Steven, you have to admit that tree rings as a temperature proxy are a fail. This has been known for decades. Steve Mc has spent his vacation showing the lunacy of tree rings as a temperature proxy. This he did in spades. Why would it show the LIA if it did not show a hockey stick? Your point is moot.
For supposedly learned men, you both seem rather obtuse sometimes.
Sent from my phone. The growing season here in NE Oregon has been extremely short. Yet we have had hot daytime temps and dry conditions. Be careful how u interprete tree rings.
David Ball says:
September 11, 2012 at 1:33 pm
you have to admit that tree rings as a temperature proxy are a fail. This has been known for decades.
Using the 18O isotope as the indicator is independent of the material being wood. The isotope method works with any material containing oxygen: chalk, wood, ice, whatever. So [and that is the main point of the paper], the first graph should be fine.
Now see if you can find a rainfall record and compare that to the tree ring data.
“Not necessarily, just introducing some caution in interpreting proxies. Of course, when the proxies confirm one’s pet theory they are good, right? And when not, they are bad [or other effects corrupt the data], right?”
I think that’s the whole point this brings up. What is the proxy really showing us? It’s flattish from end to end, using any of the measures from the trees.
I don’t envy the job of paleoclimatologists. But one thing is for sure, temperatures by these tree types don’t go spiking in the 20th century, or.. anywhere really. Seems they are happy to chug along whatever the “average” global temperature ranges.
Three rings at high latitudes follow the summer NAO (atmospheric pressure difference) rather than temperatures, see graph for 1700-1850
http://www.vukcevic.talktalk.net/TreeRingsNAO.htm
ABSTRACT:
Summer climate in the North Atlantic-European sector possesses a
principal pattern of year-to-year variability that is the parallel
to the well-known North Atlantic Oscillation in winter. The summer
North Atlantic Oscillation (SNAO) is defined here as the first
empirical orthogonal function (EOF) of observed summertime
extratropical North Atlantic pressure at mean sea level…….
Reconstruction based on 7 tree ring chronologies in Norway
and the UK:
data: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/snao-folland2009.txt
Why did’nt they just saw through the legs of the plastic tables in Starbucks and count the rings? The results would have been just as relevant and the vandalism to Starbucks would reflect the vandalism to proper science
SanityP says (September 11, 2012 at 10:59 am): “To me that indicates the uselesness of treating trees as proxies for temperatures.”
I seem to recall a paper discussed here on WUWT claiming that plants tend to maintain an internal temperature that varies less than their external environment. Sorry, can’t remember details.
Leif Svalgaard wrote:
But some indication of the MWP has been found in Bristlcone pines, and was even reported on -before it became heretical.
And in foxtail pines
The rest of that article is worth reading.
To anybody asking where is the LIA or hot 1930’s. Tree-rings aren’t great proxies for temperature. They’re not worthless, but relying on a small sample for any geographical area or time period, is almost worthless. Michael Mann’s hockey stick was front and centre in the warmist propaganda. His claims of difficulty and expense in obtaining samples is frankly absurd. Billions have been spent on global warming research and trillions are at stake in the global economy, yet they can’t send a few guys out with a simple tool costing at most $350 to do a basic task any carpenter, handyman or indeed anyone could do after a morning’s training.
Increment borer
http://en.wikipedia.org/wiki/Increment_borer
Increment Borers
http://web.utk.edu/~grissino/borers.htm
Specifications:
Available effective length: 200, 250 350 and 400 mm. Bit diameter (measured as the diameter of the inside opening): 5.15-5.20mm, three threads.
Price term: according to the effective working length of the increment borers, the FOB China port price is:
ssz-40: US$ 64/set (effective working length is 400mm)
ssz-35: US$ 61/set (effective working length is 350mm)
ssz-30: US$ 58/set (effective working length is 300mm)
ssz-25: US$ 49/set (effective working length is 250mm)
ssz-20: US$ 45/set (effective working length is 200mm)
Haglöf Increment Borers
Using An Increment Borer
vukcevic says:
September 11, 2012 at 2:23 pm
Three rings at high latitudes follow the summer NAO (atmospheric pressure difference) rather than temperatures
You [and many others] missed the whole point of the paper: The 18O isotope method has nothing to do with the growth of tree rings, but with the temperature of the water that produced the water vapor that condensed to rain which watered the tree. http://en.wikipedia.org/wiki/Oxygen_isotope_ratio_cycle