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!
It has always troubled me that all of the warming periods except the one we are currently in have a very pointed peak when it comes to temperature. The current one has a flat top instead of a peak. Either something is very special about this warming period and past history is not useful or we have a problem in our current measurements. The data you present indicates we may have a problem with current measurements. This could be ground breaking.
Dena, the flat top on the charts may be a function of the number of data points [including proxies], which are much more numerous in the Holocene.
To me, the graph looks a lot like the ringing of an ECL circuit going from a low to a high. That would indicate some negative feedback mechanisms.
Ralph Woods says:
May 26, 2010 at 4:29 pm
Just an armchair observer – it seems like temperature over very long periods seeks some stability point. Sort of like a pendulum swinging back and forth and then finding its zero point.
Neither stable nor zero. The first does not seem to happen and the second better not. Other than that . . .
Willis Eschenbach
May 26, 2010 at 4:38 pm
“Indeed, that is the question … however, I don’t know the answer. ”
Are you still using that dated “Scientific Method” thing? Get with the program. The correct answer is, “Its man’s fault, and its worse then we thought!”
Willis,
Sorry, .6 not 6.
The following NOAA link has a chart of temperatures from several sources back to -20,000 years. It also has this statement:
In addition, there was probably a short-lived period of particularly high freshwater flux about 13,000 years ago that is not shown in this figure, resulting from a large discharge of freshwater from a glacial lake in North America.
http://www.ncdc.noaa.gov/paleo/abrupt/data4.html
Above that it mentions the flow of water to the North Atlantic via the St. Lawrence River.
I do not see mentioned the flow out the Mohawk River drainage of NY State, nor that down the Mississippi R., nor of the Missoula Floods. I suspect there are many other sources world wide during those same times that brought cold fresh water and ice to the rising oceans. I’ve not found a summary source nor good dates.
I think it odd that the quoted source used the singular ‘lake’ and not the plural ‘lakes’.
So, what exactly does “we are currently at the cold end of the Holocene” mean?
Historically, what’s next? Up or down? The word “end” in that sentence indicates to me the Holocene is about to end. Correct?
Willis,
Thanks! Just… Thanks.
This is the kind of information that makes Watts Up With That such a great site! It’s such a great place to learn all sorts of things. Like the word “speleothems”! That was a new one on me.
Many thanks for your efforts, and of course, to Anthony and the mods.
Always use Google Scholar to check for pdf files.
http://dky.njnu.edu.cn/geoguanli/edit/UploadFile/200822914847689.pdf
Some speculate that the cooling of the Younger Dryas was caused by melt-water from the abrupt earlier warming. I don’t know so I will remain sceptical.
http://www.ldeo.columbia.edu/res/pi/arch/examples.shtml
http://www.ace.mmu.ac.uk/resources/gcc/5-3-2-1.html
http://www.bbc.co.uk/dna/h2g2/A760240
John Hultquist wrote: “I think it odd that the quoted source used the singular ‘lake’ and not the plural ‘lakes’.”
The lake they were referring to is Lake Agassiz.
http://en.wikipedia.org/wiki/Lake_Agassiz
“Lake Agassiz was an immense glacial lake located in the center of North America. Fed by glacial runoff at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined, and it held more water than contained by all lakes in the world today.”
MattN,
I think Willis meant this. The start of the Holocene had higher average temps. We’re at the colder end of the chart.
I don’t think Willis meant the Holocene is about to end. We don’t know that. But it’s possible.
DB, I agree they likely meant Lake Agassiz but still it didn’t just drain out the St. Lawrence River nor all at once.
http://www.eeescience.utoledo.edu/faculty/Fisher/Fisher-%20Chronology%20of%20glacial%20Lake%20Agassiz%20meltwater%20routed%20to%20the%20Gulf%20of%20Mexico.pdf
And it was not the only lake contributing to the northern oceans.
The end of the Holocene is inevitable if one draws on full geologic history as a guide, Smokey.
I just don’t want to witness it.
I’m guessing the 2nd low in the graph is the time of the grassland Sahara.
Extend the graph back another 5-10,000 years should take it to the end of the Laurnetide.
Seems a shame so few southern hemisphere records. WRT Australia, would it be possible for the CSIRO to put more effort into collecting this type of raw data? Perhaps the resources they put into computer modelling could be diverted. The CSIRO might get more original multi-cited papers out of SH data collection, since they have better access to the study areas. In the computer modelling side the CSIRO is competing with huge resources from other countries. Much less chance of ground breaking multi-cited papers. Can anyone suggest a person with influence who could be contacted with these thoughts?
“This is open source Science”
ALL SCIENCE IS OPEN SOURCE.
Anything that is not open source is not science, don’t let any PhD tell you otherwise.
MattN says:
May 26, 2010 at 6:38 pm
Sorry for the lack of clarity. There’s two ends to the Holocene, the start of it, and where we are now. The start was the warm end, and the part where we are now I called the cold end. Doesn’t mean that the Holocene is about to end, we don’t know that. The general assumption is that we are due or overdue for an ice age … but the Earth seems to pay little attention to assumptions.
rbateman says:
May 26, 2010 at 7:19 pm
Well, there was a time when there were no regular ice ages. Then regular ice ages started. Someday, I assume that regular ice ages will end … so I would hardly call another ice age “inevitable”. “Very probable”, sure, but inevitable, no.
Complacent Liberal Media Coverage of the Gulf Oil Spill
The Younger Dryas event as discussed earlier may have something to do with a large impact on the North American ice sheet. As it turned things cooler for a millennia, perhaps it was the event that truncated the expected post-glacial spike. That cooling and the death of the mega-fauna in North America is consistent with the after effects of a large impact.
There was also a large post-glacial lake that spilled in the Western US – glacial Lake Missoula – that formed and broke many times, scouring the land down to the bedrock.
The 18O shows up in the rocks courtesy of the water that preciptates and deposits the rock that forms the stalagmites / stalactites in the caves. All the cave rock is water-based; either cut or depositied via the action of water over an extended period of time.
The most interesting thing about the analysis is the right side of the graph showing our slow (perhaps not so slow) and accelerating move toward the next glacial cycle. At some (perhaps all) levels, that tends to bum me out.
That bump would have been around the time Lake Missoula drained across Idaho, Washington, and Oregon, leaving us the Channeled Scablands among other things. It left an incredible place to marvel at and to imagine about the scale of it. It’s not often you see erratics the size of houses out in the middle of a high prairie.
http://wapedia.mobi/en/Glacial_erratic
Another great analysis, and another piece of the puzzle from an unexpected place.
And this is very interesting:
“These diamonds provide strong evidence for Earth’s collision with a rare swarm of carbonaceous chondrites or comets at the onset of the Younger Dryas cool interval, producing multiple airbursts and possible surface impacts, with severe repercussions for plants, animals, and humans in North America.”
Always wondered why the Younger Dryas was such a sudden event and something like this could theoretically explain it.
Willis Eschenbach says:
May 26, 2010 at 7:44 pm
rbateman says:
May 26, 2010 at 7:19 pm
The end of the Holocene is inevitable if one draws on full geologic history as a guide, Smokey.
Well, there was a time when there were no regular ice ages. Then regular ice ages started. Someday, I assume that regular ice ages will end … so I would hardly call another ice age “inevitable”. “Very probable”, sure, but inevitable, no.
Well, as the energy environment of our planet has not changed since the ice ages started , no new planets, no great sun energy variation, … I would vote for inevitable.
Sitting by the shore and watching waves coming in, after one recedes it is inevitable that the next one will come in. Not that the sea has not been calm or will not be becalmed again, but in the time frame watched the boundary conditions are such that the next wave is inevitable.
Willis says
“Well, yeah, but since the isotopes presumably formed in very different parts of the planet, and different parts have different temperatures, I would assume that the relationship d18O/T would not necessarily be the same around the world.”
Let us all remember that you used… ahem… anomaly