More Carbon Confusion
3 May 2005
A response to an article by "Scott" which might have been plagiarised from here -
Does Carbon Dating Prove the Earth is Billions of Years Old?
On yet another personal webpage devoted to Young Earth Creationism (YEC) we find again the same confusion, ignorance and misrepresentation of valid scientific methodology that has seemingly become the hallmark of creationists on the web.
Scott's article is off to bad start with its curious title, "Does Carbon Dating Prove the Earth is Billions of Years Old?”, and things never really improve much through its nine paragraphs. The question itself is a complete nonsense, as no one except creationists ever mention carbon-14 dating and the age of the Earth as being related topics. Add to that the rather unscientific term "prove" and the question of the title can be seen, rightly, as something of a non-sequitur.
To give Scott some credit, though, his first task in the article is to dispel the "common myth" that carbon-14 dating has any bearing on measurements of the age of the Earth. In fact, he spends the first four paragraphs giving a basic, but roughly correct, description of what C-14 is and what C-14 dating is based upon. However, he limits his myth dispelling to correcting only the misconception that C-14 dating is used for age determinations of "millions of years", which of course it is not. He also gives the correct reason for this, being that C-14 is a radioisotope with a half-life of ~5,600 years. Actually, the later established figure, known as the "Cambridge half-life", is 5730 ± 40 years, whereas the initial figure established by Libby et al. (the Libby half-life) is 5568 ± 30 years. (1)
What is curious are the conclusions that Scott reaches in his article. Having dutifully explained how C-14 is primarily created (i.e. solar/cosmic neutrons striking nitrogen in the atmosphere thus converting it to C-14*), he then manages to arrive at the odd assumption that carbon dating agrees with the YEC timescale of the Earth being only some 6,000 – 10,000 years old. Please note this is less than two half-lives of C-14, which will become important as we delve further into Scott's article. We should also note Scott's caveat that this supposed concordance is only apparent via interpretation "within a Biblical framework which includes a global flood ...". As we shall see, it takes considerably more than that to make carbon dating agree with YEC timescales. Scott concedes that scientists generally don't use the method for organic remains much older than ~40,000 years, although, had he bothered to check sources beyond YEC's he would have read that in some circumstances age determinations can be made up to ~70,000 years and possibly more with increasingly refined methods such as AMS (Accelerator Mass Spectrometry). (1, 10)
To allow Scott the most beneficial figures for his arguments, let's agree for the moment to an upper limit of detection of ~40,000 years for carbon dating, and the more generous YEC timeframe of a 10,000 year old Earth (although many creation "scientists" tend to prefer the 6,000 year age). This still requires either a fourfold increase in the decay of C-14, or a fourfold decrease in its creation in the atmosphere or its intake by life forms. Option one can be discarded as there is no data which suggests that isotopic decay rates vary except perhaps under extraordinarily extreme conditions, and such conditions would be deadly to life on Earth. Correction factors and calibration data which account for varying ratios of C-14/C-13/C-12 are discussed below.
Scott presents some curious and generally incorrect, or at least grossly overstated, arguments to support his beliefs. However, the first thing to note about Scott's article is that it contains no references to any scientific papers, publications, websites or even any creationist literature to support the assertions he makes. When discussing factors which affect C-14 levels and its uptake by living organisms, Scott merely glibly states his assertions and subsequent conclusions as fact. However, even a small amount of research into the subject shows that he put little effort into checking anything in his article. Let's examine his arguments one by one.
Since scientists know the amount of C-14 that the animal had to start with (based on the assumption that the amount of C-14 in the atmosphere has always been constant) and they know that a half-life is about 5, 600 years, they can work out how old the animal is.
On a very basic level, this is correct, but Scott ignores correction factors. In fact, Scott never mentions the correction factors used in C-14 dating at all in his article. It's true that the starting position of the method utilises the assumptions of the Libby half-life and a constant balance of C-12, C-13 and C-14 in the atmosphere. However, this is prior to adjustments made to correct any figures based on numerous factors, such as the type of sample being dated, its geographical and stratigraphic location, pre-treatment procedures, calibration adjustments, correction factors/multipliers, etc.
The initial Conventional Radiocarbon Age (CRA) used wood from 1890 CE (prior to extensive fossil fuel pollution of the atmosphere) as an absolute radiocarbon standard, corrected to 1950 CE, which is considered as 0 years before present (BP), and the assumptions that the isotope decay is constant and that atmospheric C-14 levels have remained stable in the past. Given that one of these assumptions has since been revised, Libby (the pioneer of C-14 dating) and his team presented strong evidence for C-14 dating. Choosing samples with independently determined ages, such as acacia wood from the tomb of the Egyptian pharaoh Zoser (or Djoser), 3rd Dynasty c.a. 2700 – 2600 BCE, Libby reasoned that such an age should represent one half-life of C-14. The C-14 dating indeed produced results which agreed with the established date of the pharaoh's reign. (1, 2)
Since then new radiocarbon standards have been introduced, such as the Oxalic Acid I and II standards, which were correlated with the original standard, and after that, standards such as the Australian National University (ANU) sucrose standard. (1)
Further to this, many studies have been done which indicate that C-14 concentration in the atmosphere has not varied appreciably over the last 20,000 years or so. Studies such as Stuiver's (3) work using lake sediments in which carbon compounds are preserved, gave calibration data for the past 22,000 years and found that radiocarbon ages remained within 500 years of the magnetic ages. Stuiver also reported that C-14 concentration in the atmosphere did not vary throughout that long period by more than 10%.
There's no mention of calibration data and correction factors in Scott's article, which might lead one to suspect that he's either totally unaware of them, or has deliberately omitted their existence. No wonder, perhaps. The various methods used to calibrate and correct C-14 dating make his arguments vanish into thin air.
Dendrochronology has been the most widely used calibration method, which uses tree-ring data overlapping between various sources, where certain ages can be reliably determined independently of C-14, and then cross-checked with C-14 dating. This method has given reliable corroboration with C-14 dating for up to ~11,000 years BP. Other methods, such as dating of corals by growth bands, cross-checked with both 230Th/234U and C-14 dating have also provided reliable calibrations. (4, 4a)
Scott seems oblivious to the extensive work done in calibrating C-14 dating methods. When considered properly one discovers that calibration methods and correction factors are independent of the decay rate of C-14, and are designed precisely to take into account fluctuating ratios of the carbon isotopes in the atmosphere, reservoir effects, etc.(5)
It sounds pretty straightforward but, like all dating methods there are many assumptions and technicalities that affect the results. For example, plants absorb less C-14 that [sic] we would expect so they test much older than they really are. The amount of C-14 in the atmosphere has also not always been constant. Tests have shown that it has changed in the last 50 years! This is because burning more fossil fuels has created more Carbon dioxide which upset the balance of C-12 and C-14 in the atmosphere making things that died in that time appear older than they really are. The testing of atomic bombs also makes things appear younger than they really are. These two examples alone show that C-14 dating, based on the assumption that the C-14 in the atmosphere has always been constant, will be wrong.
This is one of only two paragraphs in Scott's article which actually discuss the supposed problems with C-14 dating, and it's based on one very large presumption: that scientists who perform C-14 dating supposedly don't know these things and don't account for them. As with most creationist assumptions, it is spectacularly wrong. Any check of relevant information on the technique will reveal that scientists are fully aware of all these factors, and take them into account when correcting C-14 dates.
The effects of fossil fuels on the C-14 balance (the Suess or Industrial effect) is known and taken into account (and is considered to have only caused ~2% dilution. (5)) The artificially produced increase in C-14 through atomic weapon tests is also accounted for in the baseline correction for year 0 BP. However, what Scott doesn't seem to realise is that both these factors are relatively contemporaneous, i.e. only affecting the C-14 balance within the last 100 years or so. Prior to that, only fluctuations in the Earth's magnetic field strength and occasional volcanic events would have effected the C-14 atmospheric balance. Calibration data suggests that C-14 levels have varied by only up to 10% – 15% over the time period relevant to C-14 dating. (3, 9) Therefore, correction factors are a mixture of adjustments for 0 BP, sample characteristics, calibration adjustments for historical variations in C-14 ratios, reservoir effects and various other factors. In fact, they are everything that Scott seems blissfully unaware of.
Scott also states that "plants absorb less C-14 than we would expect", yet there is no reference to support this. In fact, only one reference I found mentions anything like this, and it says that "Some creationists, however, claim that certain plants can reject carbon-14 in favour of carbon-12". (9) Scott has grabbed an inch and run a mile, essentially converting "certain plants" into all plants. That's either poor research or comprehension, or outright dishonesty.
Scott is correct in suggesting that any dates utilising the assumption of constant C-14 levels would be wrong. Unfortunately for Scott, no one works on that assumption (except creationists, it seems). He has confused the starting point of the CRA method with results produced after correction.
The amount of radiation (cosmic rays) from the sun entering the earth's atmosphere affects the amount of C-14 formed and thus will affect the carbon-dating clock. The earth's magnetic field effects the amount of radiation entering the atmosphere. A strong magnetic field will resist cosmic rays and bounce them back into space. Studies into this area show that the earth's magnetic field is decreasing so more C-14 is being produced thus making the earth look older than it actually is.
It's true, as previously mentioned, that variations in the strength of the Earth's magnetic field (the dipole moment) directly affect the production of C-14. However, Scott's argument that "studies into this area" show a decrease in the field's strength is simplistic and only partially correct. Actually, studies show that the field has been decreasing for only the last ~3000 years. Prior to that, data indicates an increase and periods of fluctuation. Certainly, over the period of the last 40,000 – 50,000 years there is no indication of a steady decrease. (6) So much for Biblical timescales or creationist claims that only a decrease in field strength is evident.
Other creationist claims regarding the Earth's magnetic field, such as reversals and fluctuations (excursions) having occurred during the supposed ~1 year period of the "Flood", also present problems for the steady decrease argument. Reversals of polarity render unidirectional extrapolation on field strengths useless. (7) Creationists such as Dr. Russell Humphreys acknowledge that reversals have occurred (albeit all within the supposed "Flood" year), but as with most creation "science" hypotheses, one tends to cancel out another.
The Bible suggests that volcanoes erupted at the time of the flood. Volcanoes give out a lot of CO2 with no C-14 so this would make things appear older than they really are.
Perhaps Scott should have pointed out where the Bible "suggests" that volcanoes erupted at the time of "the Flood". In fact, this is only an assertion by certain YEC's to explain away the immense amounts of igneous rock, volcanic ash and debris, etc., found in the geologic record. It's true that volcanic eruptions eject large quantities of CO2 which are generally depleted of C-14, however, studies have shown that the effect is localised and that plants only a short distance away show normal C-14 results. (8)
The global flood recorded in Genesis would also have upset the carbon balance. The flood would have buried a huge amount of carbon which would have lowered the total amount of C-12. C-14 would have been lowered but would continue to be produced as it comes from nitrogen not animals. This would vastly affect the carbon dating dates and Creationists believe that the flood should be recorded at about 35, 000 – 45, 000 years in the carbon dating system.
Now we get to our favourite YEC assertion, the "Flood". The flood may well be recorded in Genesis, but it is noticeably absent from the geologic record. Any assumptions about what effects this mythical flood may or may not have had don't have much bearing on scientific data when the existence of the flood itself cannot be demonstrated. Interestingly, Scott's argument backfires on itself anyway. If the alleged flood did cause a temporary increase in C-14 levels, at least in ratio to C-12, then anything from that time should produce C-14 dates younger than they actually are, not older. However, the point is moot as it is only "flood geologists" and their fellow creationists who assert that such a flood happened.
Another interesting point to note is that Scott's previous argument about volcanic activity during the "Flood" works in opposition to this argument about the supposed burial of carbon. He acknowledges that eruptions produce large quantities of CO2 (depleted of C-14), which in fact would counter the increase of C-14. So, which is it Scott? Were C-14 ratios reduced or increased, or both at once? And what field and laboratory research have creationists provided to support any of these claims?
You may be curious as to what calibration and/or correction methods creationists have used to ascertain that a CRA of 35,000 – 45,000 years BP can be corrected to 6,000 – 10,000 years BP. However, you will remain curious, as Scott can't seem to bring himself to explain how this astounding correction works, or provide any reference to support this claim. If we take the mean of these two ranges (i.e. 40,000 years CRA and 8,000 years "Biblical"), that requires an 80% correction factor of the radiocarbon age! This is simply not credible. There is not one ounce of data which supports such enormous variation in either the atmospheric carbon balance or any other factors used to correct absolute radiocarbon dates. It is also telling to note that the creationist assertion that the "Flood" can be dated in CRA at 35,000 – 45,000 years BP, prior to their mysterious "corrections", gives a standard deviation of ±5,000 years! 20% of the mean figure!? That's hardly a reliable result.
Scott concludes his article with this comment:
So, in conclusion, while Creationists do not believe that C-14 dating is completely useless, it is based on many assumptions. But, interpreted within a Biblical framework which includes a global flood, C-14 dates do make sense.
It seems obvious that if we employed the methods of creationists, then C-14 dating would be completely useless, as YEC "theories" contain more assumptions than you can shake a stick at. What does "interpreted within a Biblical framework" mean anyway? That one should use 2,500 – 3,000 year old stories as a basis for deciding which scientific data you'll allow and which you'll reject!? Such an approach might be acceptable for a dogmatic religious belief, but it is not acceptable in science. Radiocarbon dates make complete sense as they are, a YEC "Biblical framework" would render them nonsensical. The logical approach would be to discard the hypothesis which has little or no evidential support and requires the most extreme corrections of the data, i.e. the YEC Biblical Creation/Flood "hypothesis".
If we go back to title of the article, "Does Carbon Dating Prove the Earth is Billions of Years Old?”, we discover that C-14 dating has nothing to do with the age of the Earth. With a normal upper detection limit of ~50,000 – 60,000 years BP, C-14 dating was never going to tell us anything about the age of the Earth, or about "billions of years". There is, of course, another little thing which Scott neglected to mention. Radiocarbon dating is not the only radiometric dating method we have. There are several methods, utilising isotopes with half-lives far in excess of C-14, which do indeed give ages of millions, and even billions of years, such as Uranium-Lead, Argon-Argon and Potassium-Argon methods. These methods are not affected by the Earth's magnetic field, or pollution in the industrial age, or A-bomb tests, or even by mythical floods. There are even methods of dating which do not rely on radioisotopes at all, and provide ages from thousands to millions of years. Interestingly, it's these non-isotope dependent methods (amongst other data) that have helped to establish calibration data which confirms the reliability of methods such as radiocarbon dating.
In summary, it's obvious that Scott was woefully negligent in his research of radiocarbon dating. Although he has listed no references for his material, I think it a safe bet that his "knowledge" was likely obtained exclusively from creationist sources. The complete lack of detail and his apparent limited understanding of how C-14 dating methods actually work suggest this quite strongly. Radiocarbon dating has proven itself as a strong and reliable method. The preponderance of data supports this beyond any reasonable doubt, and through this method we have established robust chronologies for the late Pleistocene and Holocene.
* Cosmic/solar ray neutrons strike atmospheric nitrogen in the following reaction: 14N+n ==> 14C+p. The 14C is rapidly oxidised to form 14CO2. This is the C-14 which plants take in, and continues through the food chain.
2. Libby, WF. Arnold, JR. 1949. "Age Determinations by Radiocarbon Content: Checks with Samples of Known Age", Science, December 23, 1949, Vol.110. (http://hbar.phys.msu.su/gorm/fomenko/libby.htm)
3. Stuiver, Minze. 1976. "First Miami conference on isotope climatology and paleoclimatology", EOS, Vol.57, No.1, pp.830-836.
4. Burr, J. et al. 1998. "A High-Resolution Radiocarbon Calibration Between 11,700 and 12,400 Calendar Years BP Derived from 230Th Ages of Corals from Espiritu Santo Island, Vanuatu", Radiocarbon, Vol.40, No.3.
4a. Bard, E. et al. 1998. "Radiocarbon Calibration by Means of Mass Spectrometric 230Th/234U and 14C Ages of Corals: An Updated Database Including Samples from Barbados, Mururoa and Tahiti", Radiocarbon, Vol.40, No.3.
6. Meert, J. http://gondwanaresearch.com/hp/magfield.htm
8. Bruns, M. et al. 1980. "Regional Sources of Volcanic Carbon Dioxide and Their Influence on 14C Content of Present-day Plant Material", Radiocarbon, Vol.22, No.2.