Guest Post by Willis Eschenbach
In my usual peripatetic wandering around the web, I came across an interesting paper called “Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years”, in Nature Magazine (subscription required), 28 Feb. 2008 , with Supplementary Online Information.
The paper uses “speleothems” to estimate past climate conditions. Speleothems are secondary mineral deposits formed in caves. Stalactites and stalgmites are speleothems, and they come in a wide variety of sizes and shapes. Here’s a photo of some speleothems:
Figure 1. Speleothems in a New Zealand Cave.
What can we learn from the speleothems?
The authors used the speleothem data from two caves in China to investigate the climate changes over the last two glacial periods, a quarter million years or so. Being more interested in the recent past, and noticing that one of the datasets extended up to the year 1490, I decided to see what speleothems could tell us about the temperature changes in more recent times. So I got a large group of speleothem records from the NOAA Paleoclimatology web site.
I wasn’t interested in what happened thousands and thousands of years ago, so I got all of the long records that covered all or part of the period from the end of the last ice age to the present. This gave me 20 records.
The speleothems give us a record of what is called the “delta oxygen 18” (∂18O) value. This value is related to the temperature. The paper does not give the associated temperature values, so I converted them using the relationship described here as:
This is based on the average d[delta]18O/dT relation in modern precipitation (~0.6‰ °C-1), and the water-calcite fractionation that accompanies speleothem deposition (~-0.24‰ °C-1).
Decoded, this means that the change in temperature is equal to the change in ∂18O divided by (0.6 – 0.24), or ∂18O/0.36. Using that relationship, I calculated the temperatures from the various speleothems, and graphed them all with no further adjustment.
Figure 2. Raw data from 20 speleothem records. All of them have been converted from ∂18O using the relationship Temperature = ∂18O/-0.36. Black line is a 200-point Gaussian average. Different records are different colors.
While this was interesting, it appeared to me that the various records were likely not vertically aligned quite properly. After all, there is no a priori reason to think that they would all fit together, since they were simple anomalies (data minus average of that data) over different time periods.
So how to adjust them? There are several methods that are used to make this kind of adjustment to temperature anomalies for the global temperature records. GISS takes an average of two records in the area where they overlap, and adjusts on that basis. That was possible here, but seemed inaccurate. GHCN, on the other hand, uses one type of “first difference” method. However, their method requires that all of the datasets be on the same basis (annual, monthly, etc.), where in this case the measurements are at various random times that differ between datasets.
After some thought, I realized that I could use “first differences” in another way. The “first difference” is a new dataset that is made by calculating the difference between successive datasets. For example, if the dataset is {1, 2, 4, 8, 10}, then the first difference of that dataset is {(2-1), (4-2), (8-4), (10-8)}, or {1, 2, 4, 2}. This represents the differences between the points in the original dataset.
I realized that the standard deviation of the first difference is a measure of how well the various datasets fit together. (Standard deviation, “SD”, is a measure of how scattered the data is.)
So to adjust them, I first combined all of the 20 speleothem datasets into one single large dataset. Then I took the first difference of that single dataset. I measured the SD of the first difference data.
Then I adjusted each of the individual speleothem records by moving it slightly upwards and downwards, and used the increase or decrease of the SD to indicate which way it should be moved. I repeated this until the match was not improved by further testing and moving of the individual datasets. The result is shown in Figure 3.
Figure 3. Adjusted data from the same 20 speleothem records. All of them have been adjusted vertically to give the best fit. Black line is a 200-point Gaussian average.
This has improved the accuracy of the reconstruction. This is shown by the greater vertical range of the Gaussian average line.
So, what does all this mean? Heck, I don’t know, I’m investigating, not drawing conclusions. A few comments, in no particular order:
• As is shown in the Greenland ice core records, we are currently at the cold end of the Holocene (the current interglacial).
• Recent phenomena (Roman Warm Period, Medieval Warm Period, Current Warm Period) are scarcely visible at this scale. So much for the “uprecedented” nature of the recent rise.
• The polar bears are not in any danger from the recent rise.
• What’s up with the big jump and drop about 12000 years ago? I have not seen that in the ice core records, but it is present in these speleothem records from around the planet. [Update] A number of people have pointed out that this is almost certainly the “Younger Dryas” event. I hadn’t noticed it in the Vostok record, but a closeup of that record shows it.
• The amount of the temperature change depends on the coefficient used to translate from d18O to temperature. So the numbers are likely in the right range, but may be somewhat too large or too small.
Anyhow, that’s my thoughts about what I’ve found out, I welcome yours. I continue with the investigation. It strikes me that I may be able to adjust the conversion factor (d18O/T) to see if that improves the fit of the data … should be interesting. Onwards …
DATA:
The caves used in this study were:
Cave, Location
Borneo_sch01, Borneo
Borneo_sch02, Borneo
Buckeye, Central US
Chilibrillo, Panama
Cold_Air, South Africa
Crystal, Midwest USA
Dayu, Central China
Dongge, Eastern China
Dongge04, Eastern China
Dongge05a, Eastern China
Heshang, Central China
Liang_Luar, Indonesia
Lianhua, Southern China
Lynds, Tasmania
Mystery, Midwest USA
Sanbao08, Central China
Sanbao10, Central China
Soreq_Bar, Israel
Spannagel, Austria
Venado, Costa Rica
In two cases, where there were several speleothem records from the same cave analysed by the same investigators, I have combined them into a single longer record. Data from different studies of the same cave have a year (e.g. “08”,”10″) appended to the name.
I have posted the data I used, along with the R file that I wrote to analyze the data, as a zip file here. Enjoy!
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speleo PhD student says:
May 27, 2010 at 11:24 am
Dear Willis, I am afraid William Roberts is right on this. I am doing a PhD on speleothems and climate. The interpretation of d18O depends on many factors, and primarily on cave location. ….
Please don’t get me wrong. I support scepticism and open science. However, doing a bit more research before you start your analysis will dramatically enhance your credibility. I hope you see my point.
___________________________________________________________________________
I was wondering about the rain fall dependency. However from the caves I explored, the spelothems were always wet on the bottom so although the rate of growth is related to the amount of rainfall and the width of the growth bands can be used to determine wet vs dry years, wouldn’t the O18 be dependent on how long it took for the water to move into and out of the water table into the cave?
What I find interesting is, even though there is the confounding, you get a strong signature of “something” common to all 20 data sets. Temperature? Temperature plus precipitation? Precipitation only?
It may not be what Willis was initially looking for but it is still worth seeing.
Ryan says:
May 27, 2010 at 3:10 am
Hers are in years before present (BP), mine is in BC/AD.
William Roberts says:
May 27, 2010 at 9:00 am
Oh, please, spare us the sanctimony. Yes, d18O is related to both precipitation and temperature … but unlike with the tree rings, there is no “inverted-U” shape to the response, and in addition, precipitation and temperature are directly correlated.
As a result, the d18O level is correlated to both precipitation and temperature … so what? A warmer world is a wetter world, so that’s what we are measuring with d18O.
Finally, extreme claims like yours would benefit greatly from a healthy dose of citations … without them, you look kinda naked.
speleo PhD student says:
May 27, 2010 at 11:24 am
Since as you say it was “wet and warm”, why does it matter which one we are measuring? See below for more on this question.
speleo, I showed a host of proxies from around the planet, including a number of places with no monsoons at all. The proxies agree very well with each other. So if you want to claim that d18O shows monsoon conditions, you need to stop handwaving and start explaining why the non-monsoon areas show the same pattern of results as do the monsoon areas.
Yes, d18O records do reflect rainfall … but then, as you point out above, rainfall reflects temperature. This is particularly true in monsoon areas. So I don’t understand what your point is here. Warmer temps mean more rain, so why is there an issue?
speleo PhD student:
don’t bother arguing with these writers here. While claiming to be skeptics, they are really “antis” rather than skeptics. “Anti” anything that interferes with their Objectivist and Libertarian viewpoints that an individual should be able to do whatever they wish to do free from government and societal restraints.
Step on the poor slob in the gutter “he deserves to be there and I am better” is their motto. Ayn Rand would be proud.
There actually is no “science” reported here, just fabricated articles cherry picking data and written from their “anti” slant.
One wonders who is funding them for all their time as they seem very prodigious in the volume of crap they post.
Don Easterbrook
Who is the paper written by and which Journal is it going to be published in?
Willis, did you plot the Dongge cave record individually? What do you see? Even better, plot all the monsoon records and also the records that are INTERPRETED AS RAINFALL IN THE ORIGINAL ARTICLE altogether (for instance, Soreq cave record). You will see that, in the “wet and warm” early Holocene, d18O will turn sharply NEGATIVE, and you interpret negative d18O as cooler temperatures for the rest of the records, don’t you? So, does d18O work as a temp proxy for the rainfall-proxy regions? NO. “Wet-and-warm” argument is NOT reflected by d18O. Wet makes d18O more negative, but warm makes it more positive! Show us monsoon records and non-monsoon records seperately, and everyone will get the issue.
The first thing you should do is to skim through all the original papers associated with the data sets, eliminate all the data sets in which d18O is interpreted as a rainfall proxy. And and and.. d18O is influenced also by seasonality of rainfall, did you know? Imagine, if you have a shift to more summer rainfall with the same total annual precip amount, wouldn’t you get higher values of d18O? Even if the temperatures do not change? You should also eliminate data sets for which this effect can be important. And you CAN NOT decide before reading the original papers.
I believe that Early Holocene was warmer and wetter than present in the Northern Hemisphere. But this is no argument against the current warming, because the reason for the Early Holocene warmth is very well established. It is the increased summer-time solar irradiance due to the state of Milankovitch cycles. And: If you attempt doing paleoclimatology without any knowledge of the Younger Dryas… I don’t know what to say…
The “warmists” out there, especially the ones at realclimate, are so happy when they see posts like yours. Your analysis is invalid and your claims are easily refutable using well-known facts. I am sorry, but you give skeptic community a bad name, with “works” like this. I can’t imagine Steve McIntyre doing this.
Harvey said
“While claiming to be skeptics, they are really “antis” rather than skeptics. “Anti” anything that interferes with their Objectivist and Libertarian viewpoints that an individual should be able to do whatever they wish to do free from government and societal restraints.”
Wow Harvey you are certainly coming late to the party whilst wearing a blindfold if you believe that the nonsense you regurgitate here is a fair representation of the many and varied viewpoints of those who post on WUWT.
Why don’t you stick around, write something sensible, and get to know us a bit better THEN make a judgement.
Tonyb
speleo PhD student,
Observe harvey like one of your speleothems. He is a typical example of a closed-minded, fact-free troll. We get them here on occasion.
Rather than contribute something worthwhile to the conversation, he makes completely baseless, false accusations on the internet’s “Best Science” site.
No doubt Harvey is taking a time out from his RealClimate echo chamber home to make his hit ‘n’ run drive-by comment.
I would just like for Harvey to tell me one thing: who is supposed to be funding me, and when will my check be in the mail?
speleo PhD student,
I gave you a strange subject to consider, a species of internet troll, but you insist on sticking to your specialty.
OK then, have it your way. But don’t criticize Willis for writing interesting articles. Anthony is always looking for new articles — why don’t you write one for WUWT? I would look forward to the genuine peer review you would receive here.
You could tie in your speleo article with the low correlation that tree proxies have to temperature [you know, the same proxies that Michael Mann and Caspar Amman used to try and get rid of the MWP and LIA].
So you see, even seasoned experts often get it wrong, whether deliberately or through ignorance. My advice is that you should write that article right now, while you still know it all.
@ur momisugly Smokey: I am well aware that proxies are distorted by paleoclimate scientists as well, but bad science cannot be debunked by bad science. I wonder why people like Willis are so impatient just to “write” and to “reconstruct” something, when they could do much better with a little bit more effort and attention. Fighting back with bad science only makes the “establishment” more powerful, and in turn my life more miserable. I cannot defend Willis and support skeptic community (which I would really like to), if the products are this quality.
About the article: I’ll publish some formal ones first (I must). After obtaining the PhD and getting more independent, everything will be easier. I promise to return.
Perhaps these trolls are resentful about any cave-based research.
I thought it was a very interesting article and discussion.
speleo PhD student says:
May 27, 2010 at 2:51 pm
You know, the first thing you should do is climb down off of your high horse and stop with your foolish assumptions. I did more than skim all of the original information. I also plotted a total of 46 different cave d18O records, every record I downloaded. That’s basic science on my planet. Onwards to your point:
Well … no, I don’t. Like other researchers in the field, I interpret more negative d18O as indicating warmer temperatures. Here, for example, is the graph from the Spannagel cave record:
Note that Spannagel agrees with me, that more negative d18O values indicate warmer temperatures. I thought you were studying this stuff …
Now, I’ve used that Spannagel interpretation throughout my analysis, that negative d18O shows warmer temperatures. The result is the good agreement between the records shown in the head post Figure 3. If you think that it is all upside down, well, turn it over and you can explain why (contrary to the ice core records) your interpretation is that the planet has been gradually warming since the end of the last ice age, and why the Younger Dryas event looks so funny …
Or perhaps your contention is that we are just looking at rainfall records, and that Figure 3 shows historical rainfall? Or inverted historical rainfall? Or is it your contention that some of what I used are rainfall records, and some are temperature records, and the good agreement between them all is just a coincidence?
Next, to substantiate my claim that warm = wet, here’s another quote, this one from the Wanxiang info:
… and from the Qunf cave (Oman) info:
In other words, in general, a warmer world is a wetter world … funny, huh? My interpretation is that negative d18O records indicate warmer and wetter. I don’t really care about the exact ratio between the two, because it seems to average out in the wash.
In the meantime, previously I would have said that climate scientists were the most condescending group of scientists imaginable. Now that I’ve seen a climate science PhD student, however, I’m starting to revise my opinion … dude, we’re all just trying to understand things here. Like I said,
So take a Prozac or drink a beer or something, your assumption that you have the word from on high and we’re all just fools who don’t do our homework is getting boring. You are starting from behind by posting anonymously, why make it worse? If you find errors, I’m happy to discuss them, but let’s discuss them like gentlemen. I’m always happy to learn, and I can live with being proven wrong, that’s why I’m a scientist … I get to experience both, in the most public fashion.
But don’t try to lecture me as if I were one of your teaching assistants.
Thanks, Willis, for being honest about your fudge factors and assumptions.
Refreshingly Open Source science! 🙂
Dear Willis, it is not safe for me to use my real name. Apologies for that.
Yes, I tried to lecture you, which was much needed. I don’t see why lecturing should be wrong, this is my area.
You still seem not wanting to understand the basics of this science. The correlation between “temperature” and “d18O in modern precip” is POSITIVE. Accordingly, in your text, you correctly found a value of +0.36 per mil d18O change for every degree celcius, after subtracting the deposition effect… This means, if you assume all other effects (amount effect, seasonality, precip source effect etc.) to be non-existent, you will observe 0.36 per mil more positive d18O for every degree C. This positive relationship is what we observe in all the ice core records as well, and all researchers in the field know this. This has nothing to do with caves, this is basic isotopic fractination. Spannagel cave record is a rare example of the reversed relationship, where the source effect plays a role (read the paper). And, monsoon records have their own story, through their own mechanism, which I explained above.
So, 1) if you assume an inverse relationship between temp and d18O, maybe you made a mistake. This is plain wrong. This is contrary to your very first calculation. 2) You cannot take Spannagel or Monsoon records as references for this assumption… Spannagel’s reasoning is through the “variable source effect”, due to a special geographical location, and temperature is only INDIRECTLY related to this and authors make use of that fact (read the paper). Therefore you cannot use this reasoning for all of your collected data.
Thanks for the discussion by the way. What I say is: study more before publishing.
By the way, Willis, why didn’t you include Sofular cave data (Fleitmann et al, also on the NOAA web page) in your analysis ? With your assumption, the d18O values of that record would indicate a warm glacial and a cold Holocene.. interesting.
speleo PhD student says:
May 27, 2010 at 7:05 pm
Not safe for you to post under your real name? What has science come to, when an man can’t freely express his scientific opinions?
In any case, you’re arguing with the wrong guy on this question. I showed above that the people who analyzed the temperatures in the Spannagel cave say the opposite of what you say … go argue with them. You say that they say temperature is only INDIRECTLY related to d18O in their study … but they show it is linearly and inversely related.
Nor do I find in their text your claim that temperature is only INDIRECTLY related to d18O. The text is here, perhaps you can point out to me where it says that the Spannagel cave is unlike other caves in that there is an inverse relationship between d18O and temperature, and why it is unlike other speleothems. In section 3.1 they say that
But I can’t find anywhere that they say that the relationship is usually the inverse of the relationship that they find in Spannagel.
The relationship is in fact positive in the ice cores. But in the cave data, and in carbonates, it is negative.
Here’s a quote from “A 780-year annually resolved record of Indian Ocean monsoon precipitation from a speleothem from south Oman”, which is here (emphasis mine):
In other words, the stronger the temperature, the stronger the vertical convection, the more rainfall, and the lower the d18O. Here’s another citation:
So I don’t see why you are comparing caves to ice cores, when it is well known that carbonate precipitates in general go the other direction from ice cores.
I didn’t include it because, of all of the cave records I looked at, it was the only one that showed your “more d18O = higher temperature” relationship. I didn’t understand this (and still don’t), since all of the other caves showed the opposite. The paper related to the Sofular cave shows that it has the opposite response to the Hulu cave (see Figure 1) … but they didn’t say why it should be that way.
Since Sofular was opposite in sense to all of the other caves I looked at, and since the authors didn’t say why that was the case, I left it out rather than flip it over. However, if you have an explanation of why the Sofular cave is an outlier, I’m happy to listen.
I note that you did not answer my questions, which in a person who seems determined to lecture is a very bad habit. So I’ll ask again:
If my interpretation is wrong, wrong, wrong as you say … then surely my questions must have simple answers.
speleo PhD student, here’s some more information. This is from How to “calibrate” speleothem proxy data: a critical review. Note the negative slope of the line, which clearly shows that for calcite (speleothems), as temperatures warm, d18O drops …
So I may be wrong … but if so, I’m in good company.
I love it here, there is always more to learn in these discussions. Caves swing both ways. From here:
So it looks like all of the caves that I looked at had negative d18O[speleothem]—MAT relationships (more positive d18O[speleothem] values indicate lower temperatures), with the exception of the Sofular cave that speleo PhD student mentioned above. So I have oriented them correctly.
Contrary to the advice of speleo PhD student, I often publish to learn, rather than to lecture, and this is an excellent example. I have learned an enormous amount through all of this. As I said at the top of the thread, “So, what does all this mean? Heck, I don’t know, I’m investigating, not drawing conclusions.”
Willis, I wish I could continue discussing in much more detail but I don’t have time. You raised good points, however at the end, you will refute your own very first assumption, if you go on investigating. First of all, your first calculation reveals a positive d18O-temp relation, but you seem to be ignoring your own assumption. Second, d18O-Temp relationship may be in both ways, this is true, but you cannot take the inverse relationship out of context and use it as you want. For instance, time scale matters. On the very long term (the time frame of your analysis), if there is a relationship between temp and d18O, it must be a positive one – that’s why Sofular cave record is the other way around. All the other data sets you include are either rainfall records, or have something special to interpret the opposite. Again: rainfall cannot be regarded going always hand in hand with temperature… this is, believe me, a very bad assumption. Please don’t be the Michael Mann of the skeptic community, he does similar things. About Spannagel: inverse temp-d18O relationship is NOT assumed for the longer record… It is just for a part of the Holocene. In fact, for another stalagmite record from the same cave, which spans longer times and includes glacial/interglacial shifts (as in your analysis), the interpretation is the opposite:
“Part of the stalagmite shows three prominent δ18O maxima which according to the age model represent the three interglacials”
http://www.uibk.ac.at/geologie/pdf/spoetl08a.pdf
Willis
All credit to you for producing this article. I can’t help wondering that if only Al Gore had invented the internet earlier, what the debate would have been like if young and inexperienced Dr Mann had put up his tree rings work for open discussion on a forum such as this.
To me his findings were always ‘work in progress’ that begged many questions and much debate. Instead it was fast tracked to glory.
tonyb
—
Writes Willis Eschenbach: “Not safe for you to post under your real name? What has science come to, when an man can’t freely express his scientific opinions?”
Er, Willis…. Where the hell have you been for the past thirty years or so? speleo PhD student has every possible good and credible reason to fear for his professional life when posting honest opinion – whether he is in error or not – on a forum such as this one.
One of the great values of anonymity (or pseudonymity) is that it facilitates this kind of wrangle. A scientist who does not have to worry about “going on the record” is not only able to blue-sky stuff that is brutally suppressed by superiors and other lictors but must also make his arguments intrinsically lucid, logical, and supported.
The writer functioning under a pseudonym has no “clout.” What you see in his posts is what you get, and his credentials don’t matter.
Dunno about anybody else, but I think that’s a major good thing.
The ability to hang stuff out there without fear of any consequences other than getting your nose yanked is also a major good thing, no? For any speleo PhD student who is in the process of trying his professional muscles, participation under a false name in a venue like this one is golden.
What, you think he’s gonna get this kind of feedback – or opportunity to speak freely – among his careerist peers and preceptors?
—
” if there is a relationship between temp and d18O, it must be a positive one”
Why MUST it be positive, when other sources say that it can go either way depending on location? If you’re going to educate, lets get to the crux of the matter instead of simply stating something as fact, shall we?
@BBk: Why do you take my words out of their context? I said:
“ON THE VERY LONG TERM (the time frame of your analysis), if there is a relationship between temp and d18O, it must be a positive one – that’s why Sofular cave record is the other way around.”
This is so, because the temperature difference between glacial/interglacial is so high that the first-order temp-d18O relationship (temp+ -> d18O+, which Willis derived correctly at the very beginning, but strangely utilized in the opposite way) dominates, unless your record comes from an area where the d18O-precip amount relationship (precip + -> d18 -) dominates even the first-order temp effect. The inverse relationship is, on the long term, not with temp but with precip.
I did not say “if there is a relationship between temp and d18O, it must be a positive one”, alone.
@Rich Materese: Thanks for understanding my concerns. You are spot on.
Willis, apologies for my earlier remark. I clearly didn’t have my brain engaged when I didn’t spot the difference in horizontal scales used!
I think it is key here to understand if this proxy is “bang-up-to-date” i.e. the last data is indicative of the state of present day temps rather than 1000 yrs ago. The ice-core data is not so0 up to date, because ice-cores take time to freeze in the record of the temp proxies.
However, I notice with interest that the orange dots appear to have the same pattern as the purple dots but displaced by about 1500 yrs. Could that be because they are caves in different hemispheres? – there was a comment earlier in this thread that climate patterns in the northern hemisphere follow the southern hemisphere by 1500yrs, according to the ice-core record. or maybe the cave is just deeper?
As I said before, the thing that interests me more is the fact that we seem to be about 1/3rd of the way through a linear decline from the peak temperatures immediately after the end of the last ice-age to the worst part of the next ice-age. This is what the ice-cores say should be happening, in which case the CO2 clearly isn’t doing nearly enough to stop the next ice-age happening!