Guest opinion: Dr. Tim Ball | When Did It Occur?
Lack of information is a major problem in reconstructing and understanding climate and climate mechanisms. H.H.Lamb gave it as his reason for creating the Climatic Research Unit (CRU).
“…it was clear that the first and greatest need was to establish the facts of the past record of the natural climate in times before any side effects of human activities could well be important.”
Notice he is talking about “the facts”, which includes data and other measures. Chief among the other measures are accurate chronologies, which is why he discusses dates and dating methods at some length in Volume 2 of his Climate, Present, Past and Future.
Lamb also divided climate studies into three major areas based on time and method. The secular or instrumental period covers at most 100 years. Few stations are longer and almost all are in Western Europe or eastern North America. The historical period includes the recorded works of humans and covers at most 3000 years. The biologic/geologic record covers the remainder of time. The degree of accuracy diminishes both in measures, such as temperature and precision of dates, as you go back in time. One tragedy of the “hockey stick” rarely discussed was that it misused and demeaned the value of one of the few measures that transcends two or three of these divisions.
Climate is the study of change over time, or average conditions in a region. It is almost impossible to study climate change without accurate dates. For example, a major debate in climatology is the extent to which climate is cyclical. If the dates of events are inaccurate, it is not possible to determine the length of cycles and how they interact. You can, and likely will, draw completely wrong conclusions.
For example, I participated in a fur trade history conference when a paper by an historian claimed ice conditions on Lake Michigan occurred at very different dates than today and were proof of climate change. His source was a fur trader’s journal. Questioning revealed he was unaware that the fur trader used a Julian Calendar and the British government changed to the Gregorian Calendar in 1752, adding eleven days. (Figure 1)
Calendar changes are just one example of disconnects, between our thinking, understanding, teachings, and reality. Calendars are essentially fixed, human constructs, while nature is constantly changing. The Egyptians, among others, struggled with this problem. Their calendar had 12 months of 30 days, which was so out of phase with reality after 400 years they simply declared a holiday for the missing five days. Later, they decided that flooding of the Nile, critical to their food production, was the beginning and end of their year. They tied it to a physical event, namely the rising of the Dog Star, Sirius.
The Egyptian change was triggered by the growing discrepancy with natural events. The change from Julian to Gregorian was mostly pushed by the gap between the agricultural seasons and natural events. Annual climate change is problematic, but it becomes even more complex when dealing with segments of the year, such as seasons. Most significant dates in the human calendar are related to the interaction between climate, nature and food supply. The Farmers Almanac and much folklore is accumulated empirical information about agriculture, the weather and climate. The problem is so much of it is related to a specific region. For example, English proverbs say, “If the leaves do not fall before St Martin’s (November 11), expect a cold winter.” Or, A green Christmas, a fat churchyard.” It is apparent these are related to the pattern of the Circumpolar Vortex, but the impact depends on the latitude and the longer climate pattern of the time. Conditions were quite different between the Medieval Warm Period (MWP) and the Little Ice Age (LIA). The problem is exacerbated when the proverb was created in Europe and was then transposed to another part of the world.
Another problem for calendars, and dating in general, is establishing a datum. The millennium change to the 21st century triggered much discussion about eliminating AD and BC. Radiocarbon dating, discussed later, established January 1st 1950 AD as the base year and called it 1950 BP for Before Present. The switch to the new millennium was interesting because it ushered in the era of exploitation of extreme alarmism. Known as Y2K, many claimed computers would fail because of the inability to switch to the new date sequence. They scared people so much that everyone celebrated in the wrong year. Technically, the new millennium begins in 2001, but the celebration occurred in 2000. Maybe we should have a calendar that begins with the Big Bang, but then, what would the error range be?
Robert Claiborne wrote a book (1978) titled Climate, Man and History. It received little academic attention because Claiborne was, to say the least, a man of eclectic interests. He was too diversified for the increasingly narrow, specialized, academic world. The book intrigued me because it addressed an issue that troubled me, namely that I was getting different dates and sequences of events in different university courses. Claiborne noted that anthropologists were on a different time-scale than glaciologists and climatologists. As I recall, he wanted to do a doctoral thesis on the subject, but it was rejected, so he wrote the book instead.
Two Dating Categories in Climate
Lamb identified Absolute and Relative as the two major divisions of dating in climate studies. They are the same divisions anthropologists use as they try to create an accurate chronology for pre-history. It is mandatory for understanding cause and effect.
Relative Dating is the simplest because it relates events to a fixed or known date. For example, in parts of North America archeologists, a branch of physical anthropology, determine if an event is pre- or post Mazama. This is reference to a layer of volcanic ash laid down across the continent by eruption of Mt Mazama, now marked by the enormous caldera filled by Crater Lake.
Relative Dating is dependent on Absolute Dating. Technically, all you can say accurately is that an event occurred before or after the Absolute Dating event. Of course, this assumes Absolute Dating has an absolute precision, but that is not the case.
Problems occur because of the early assumption that certain natural events occur with an absolute precision. This created many problems and caused many changes in understanding sequences of events. Two examples will illustrate them as they relate to climate.
Radiocarbon dating was developed from concepts proposed by Willard Libby in 1933, however, they only became established after WW II. It was quickly adopted by archaeology and gradually intruded into other disciplines, where sequence and timing of events was critical.
Milankovitch created a cycle of climate conditions that indicated a glaciation sequence in Alaska. Radiocarbon dating of trees for a region conflicted with his chronology. Since radiocarbon was ‘new’ and ‘more scientific’ it over rode Milankovitch. Prior to 1950, his theory was generally accepted, but after that it was rejected. I recall conferences in the 1960s and 70s at which any reference of a cyclical trend to Milankovitch was automatically rejected. His son, in a poignant article about his father’s lifework, claimed he died of a broken heart. It was not until the late 1980s that I heard a paper referencing Milankovitch, with no challenge.
Part of the reason for the change was that an error in assumption about radiocarbon dating was discovered. As one article explains,
Every scientific method has its limitations. This is because the fundamental assumptions or axioms, on which a method like carbon dating is based, are only approximately true or accurate. All the physical laws we know have limits of validity. The fact that scientific methods like these, fail beyond a certain domain of approximation, doesn’t make them redundant. It only means that these need to be used with caution and with a knowledge of the limits of their accuracy.
Most forms of absolute dating involve supposedly precise measurable rates of a natural process, like the rate of decay of carbon 14. It sounds precise, but all measures are presented with a range, which increases as you extend back, to the maximum range of the technique, 60,000 years. A classic example is the radiocarbon dates for the Shroud of Turin, which are given as 1260-1390 AD with a 95 percent confidence; the range of 130 years covers most of the modern instrumental record. It is a good example because the fervent and political interest means the problems and limitations of the method are discussed to an extreme level. A computer search for absolute dating methods returns many sources from a creationist perspective. Ironically, this vulnerability illustrates the problems with scientific dating techniques.
Another form of radioactive decay and the one most widely used, is Potassium/Argon (K-Ar) dating. This measures the measures the decay of Potassium- 40 to Argon-40. A list of the assumptions required for reasonable results was set out by McDougall and Harrison (1999), and puts severe limitations on the viability of the results. A general claim is an accuracy of one percent, which sounds good. However, one percent of one million years is 10,000 years and in climate that effectively covers the Holocene. In reality, none of these so-called precise methods, even radiocarbon dating, are accurate enough for climate studies.
The Holocene is an example of another problem related to dating and climate. When did it begin? Who decided what temperature threshold was met and when? Anthropogenic Global Warming (AGW) advocates exploit this problem of dating when it suits them. For example, they claim the Medieval Warm Period or the Little Ice Age did not occur because evidence shows they were not uniformly global. Climate studies try to deal with this by the procedure of relative homogeneity. In my study of climate at Churchill, Manitoba I also examined the climate at York Factory, 220 km apart, to determine and separate regional from local change.
This article cannot cover all the forms and methods of establishing absolute or relative dating. Its goal is to raise the issue of the limits of the methods and subsequent accuracy. Both are essential to understanding climate and especially climate change. However, a brief list of those that have influenced climate change studies includes: Rhythmites, such as sediment layers, tree rings, and ice layers; Lichenometry, is based on the rate of growth of lichens, which is assumed to be slow and constant; and Palynology that counts the number of pollen types in a core to provide a relative sequence of changing vegetation. Notice the dangers of autocorrelation because all of these are caused by climate change.
The right century may be enough accuracy for a shroud, but is inadequate for a climate study. Accurate dating is essential for establishing the relationship between events. The specific periodicities are crucial in achieving accurate prediction and establishing correct relationships of cause and effect. Lamb’s concerns are just as valid today as when he expressed them. If anything, they are a bigger problem because people use them without understanding the limitations. As the earlier quote said,
The fact that scientific methods like these, fail beyond a certain domain of approximation, doesn’t make them redundant. It only means that these need to be used with caution and with a knowledge of the limits of their accuracy.
Horus non numero nisi serenas. (I count only the sunny hours) – Motto on a Sundial
The only reason for time is so everything doesn’t occur at once. – Albert Einstein
I went to a restaurant that serves “breakfast at any time”. So I ordered French Toast during the Renaissance. – Steven Wright