Carbon-14 Decay Rate

How Good Are Those Young-Earth Arguments?
A Close Look at Dr. Hovind's List of Young-Earth Arguments and Other Claims
by Dave E. Matson
Copyright © 1994-2002

The following material has been taken from a sheet entitled Several Faulty Assumptions Are Used in all Radiometric Dating Methods. Carbon 14 is used for this example:, which was put out by Dr. Hovind.

Dr. Hovind (R1): The atmospheric (Carbon-14) C-14 is presently only 1/3 of the way to an equilibrium value which will be reached in 30,000 years. This nullifies the carbon-14 method as well as demonstrating that the earth is less than 10,000 years old.

The above is offered as a simple fact of research. Knowing how faulty creationist "facts" can be, let's do a little research of our own. One suspects that the scientific world would not be using the carbon-14 method if it were so obviously flawed. Could it be that the whole scientific community has missed this point, or is it another case of creationist daydreaming?

This argument was popularized by Henry Morris (1974, p.164), who used some calculations done in 1968 by Melvin Cook to get the 10,000-year figure. In 1968 another creationist, Robert L. Whitelaw, using a greater ratio of carbon-14 production to decay, concluded that only 5000 years passed since carbon-14 started forming in the atmosphere!

The argument may be compared to filling a barrel which has numerous small holes in its sides. We stick the garden hose in and turn it on full blast. The water coming out of the hose is analogous to the continuous production of carbon-14 atoms in the upper atmosphere. The barrel represents the earth's atmosphere in which the carbon-14 accumulates. The water leaking out the sides of the barrel represents the loss (mainly by radioactive decay) of the atmosphere's supply of carbon-14. Now, the fuller that barrel gets the more water is going to leak out the thoroughly perforated sides, just as more carbon-14 will decay if you have more of it around. Finally, when the water reaches a certain level in the barrel, the amount of water going into the barrel is equal to the amount leaking out the perforated sides. We say that the input and output of water is in equilibrium. The water level just sits there even though the hose is going full blast. (The barrel is made deep enough so that we don't have to worry about water overflowing the rim.)

Henry Morris argued that if we started filling up our empty barrel it would take 30,000 years to reach the equilibrium point. Thus, he concluded, if our Earth were older than 30,000 years the incoming water should just equal the water leaking out. That is, the equilibrium point should have long since been reached given the present rate of carbon-14 production and the old age of the earth. The next step in Henry Morris' argument was to show that the water level in our barrel analogy was not in equilibrium, that considerably more water was coming in than leaking out. To that end, he quoted some authorities, including Richard Lingenfelter. Having accomplished that, Morris concluded that the barrel was still in the process of being filled up and that, given the present rate of water coming in and leaking out, the filling process began only 10,000 years ago.

It's a great argument except for one, little thing. The water is not coming out of the hose at a steady rate as our model assumed! Sometimes it slows down to a trickle so that much more water is leaking out the barrel than is coming in; sometimes it goes full blast so that a lot more water is coming into the barrel than is leaking out. Thus, the mere fact that the present rate of water coming in exceeds that of the water leaking out cannot be extrapolated back to a starting time. And, that destroys the entire argument. (See Figure 1).

'The water in the barrel represents the c-14 in the atmosphere. The water coming in represents c-14 being added to the atmosphere. The leaking water represents the decay of the carbon-14. If the inflow is steady, and if equilibrium hasn't been reached, and exceptional water bug in the barrel could calculate how long the process has been going on.'

Water barrel analogy for carbon-14 in the atmosphere

Figure 1

Lingenfelter's paper was written in 1963, before the cycles of C-14 variation we described had been fully documented. The point is that fluctuations in the rate of C-14 production mean that at times the production rate will exceed the decay rate, while at other times the decay rate will be the larger.

(Strahler, 1987, p.158)

Lingenfelter actually attributed the discrepancy between the production and decay rates to possible variations in the earth's magnetic field, a conclusion which would have ruined Morris's argument. Henry Morris chose not to mention that portion of the paper! Creationists don't want their readers to be distracted with problems like that -- unless the cat is already out of the bag and something has to be said.

Tree-ring dating (see Topic 27) gives us a wonderful check on the radiocarbon dating method for the last 8000 years. That is, we can use carbon-14 dating on a given tree-ring (the 8000-year sequence having been assembled from the overlapping tree-ring patterns of living and dead trees) and compare the resulting age with the tree-ring date. A study of the deviations from the accurate tree-ring dating sequence shows that the earth's magnetic field has an important effect on carbon-14 production. When the dipole moment is strong, carbon-14 production is suppressed below normal; when it is weak, carbon-14 production is boosted above normal. What the magnetic field does is to partially shield the earth from cosmic rays which produce carbon-14 high in the atmosphere.

Contrary to creationist Barnes' totally discredited claims, which I've covered in Topic 11, the earth's magnetic field (dipole moment) has, indeed, increased and decreased over time. Strahler presents a graph of the earth's dipole moment going back 9000 years.

Figure 19.5, curve C, shows the dipole field strength calculated from measurements of magnetism of lava flows and of artifacts such as pottery and bricks, whose age can be determined. The curve is roughly fitted to mean values determined about every 500 to 1,000 years... The curve is roughly 180 degrees out of phase with the C-14 curve.

(Strahler, 1987, p.156)

The idea [that the fluctuating magnetic field affects influx of cosmic rays, which in turn affects C-14 formation rates] has been taken up by the Czech geophysicist, V. Bucha, who has been able to determine, using samples of baked clay from archeological sites, what the intensity of the earth's magnetic field was at the time in question. Even before the tree-ring calibration data were available to them, he and the archeologist, Evzen Neustupny, were able to suggest how much this would affect the radiocarbon dates. (Renfrew, p.76)

(Weber, 1982, p.27)

Thus, at least within the last 9000 years, the earth's magnetic field has fluctuated and those fluctuations have induced fluctuations in the production of carbon-14 to a noticeable extent. Therefore, as already noted, Dr. Hovind's claim that carbon-14 has been slowly building up towards a 30,000 year equilibrium is worthless. You now have the technical reason for the failure of Morris' model.

It may interest the reader to know that within this 9000-year period, where the radiocarbon method can be checked by tree-ring data, objects older than 400 BC receive a carbon-14 date which makes them appear younger than they really are! An uncorrected carbon-14 date of 6000 years for an object would actually mean that the object was 6700 years old. Seven hundred years or so is about as far as the carbon-14 method strays from tree-ring dating on the average. Individual dates given on a 1973 correlation chart (Bailey, 1989, p.100) show that objects with true ages between 4200 BC and 5400 BC would receive a carbon-14 date making them appear 500-900 years too young. As it turns out, we have a check on the carbon-14 production which goes back even further than 8000 years:

Evidence of past history of C-14 concentration in the atmosphere is now available through the past 22,000 years, using ages of lake sediments in which organic carbon compounds are preserved. Reporting before a 1976 conference on past climates, Professor Minze Stuiver of the University of Washington found that magnetic ages of the lake sediments remained within 500 years of the radiocarbon ages throughout the entire period. He reported that the concentration of C-14 in the atmosphere during that long interval did not vary by more than 10 percent (Stuiver, 1976, p. 835).

Thus, the available evidence is sufficient to validate the radiocarbon method of age determination with an error of about 10 percent for twice as long a period as the creation scenario calls for.

(Strahler, 1987, p.157)

Yes, the atmospheric content of carbon-14 can vary somewhat. The dipole moment of the earth's magnetic field, sunspot activity, the Suess effect, possible nearby supernova explosions, and even ocean absorption can have some effect on the carbon-14 concentration. However, these factors don't affect the radiocarbon dates by more than about 10-15 percent, judging from the above studies. Of course, when we reach the upper limit of the method, around 40,000 years for the standard techniques, we should allow for much greater uncertainty as the small amounts of C-14 remaining are much harder to measure.

Tree-ring data gives us a precise correction table for carbon-14 dates as far back as 8,000-9,000 years. The above study by Stuiver shows that the C-14 fluctuations in the atmosphere were quite reasonable as far back as 22,000 years ago. The earth's magnetic field seems to have the greatest effect on C-14 production, and there is no reason to believe that its strength was greatly different even 40,000 years ago. (For a refutation of Barnes' argument see Topic 11.)

Therefore, atmospheric variation in C-14 production is not a serious problem for the carbon-14 method. The evidence refutes Dr. Hovind's claim that the C-14 content of our atmosphere is in the middle of a 30,000-year buildup. Thus, we can dismiss this young-earth argument.

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