Misconception # 1: Carbon dating can be used to date objects that are millions or even billions of years old
Carbon dating is one of the most popular radioactive dating methods used today. Ironically, despite its popularity, it is also one of the most misunderstood methods of dating. Many people mistakenly believe carbon dating can be used to date objects that are millions or even billions of years old. The fact is, carbon dating can only be used to date things up to approximately 50,000 years old. In fact, if an object contains (radioactive) carbon, this should be a clue that the object may not be any older than 50,000 years.
Misconception #2: Carbon dating can be used to date virtually anything
Another misconception people have about carbon dating is that it can be used to date virtually anything. Carbon dating can only be used to date objects that were once living or even apart of a living organism. Such things are a leaf, a bone, wood, flesh, etc. It cannot be used to directly date inorganic objects, such as rocks (other radioactive dating methods are used to date radioactive rocks).
Be cautious of accepting a carbon age
One should not accept any age from a dating method, including carbon dating, without knowing exactly how the dating method works and its limitations. Many people also don’t realize that carbon dating (along with other radioactive dating methods) is based upon unverifiable assumptions. While this doesn’t render the dating method useless, it does bring its overall accuracy into question.
How radioactive carbon is formed
Normal carbon atoms weigh 12 atomic mass units, while a radioactive form of carbon weighs 14 atomic mass units, which is called carbon-14 (C-14). C-14 is a rare form of carbon. It is estimated that only one out of every trillion carbon atoms is C-14. C-14 is formed in the earth’s upper atmosphere as a consequence of cosmic radiation bombardment. These cosmic rays shatter the nuclei in gas atoms in the upper atmosphere releasing neutrons. The displaced neutrons bond with nitrogen-14 (N-14) converting it into C-14. Because C-14 is radioactive, it is unstable, and is constantly decaying back into N-14. But, as C-14 continuously decays, it is also continuously being replaced by new C-14 being formed.
How carbon-14 enters an organism
Most C-14 will combine with oxygen to produce radioactive carbon dioxide (C-14 O-2). Since plants breath carbon dioxide, they will intake some C-14 as well and make it part of their tissue. Animals, in turn, eat plants or other animals that eat plants, receiving the C-14. Even humans contain C-14 because, of course, we also eat either animals or plants (I don’t know what else there is to eat). Throughout an organism’s life, it is constantly balancing its C-14 decay with intake so that it will always contain C-14. Since C-14 is so well distributed in the atmosphere, it is assumed the same ratio that is in the atmosphere will also be in an organism.
How carbon dating is supposed to work
Once an organism dies, its C-14 decay is no longer being replaced by intake. Therefore, all the C-14 remaining in the organism will eventually decay and disappear. If one can measure the rate in which it decays, and the amount the organism started off with, then one might be able to figure out when the organism, such as a frog, croaked.
Most authorities agree that C-14 decays at such a rate that half of it will be gone in approximately 5,730 years. This means if a specimen contained, say, a pound of C-14 (to make things understandable), in 5,730 years, half of it will be gone, and in another 5,730 years, half of the remaining C-14 will disappear. After about 8 half-lives, the remaining amount of C-14 (if there is any remaining) is too small to be measured. For this reason, it is simply impossible for carbon dating to give dates as old as millions of years. Instead, it can only give up to approximately 50,000 years.
While this dating method sounds pretty good and simple enough to understand, there are some assumptions that aren’t often pointed out. Some of these assumptions are:
1. A constant decay rate.
2. Closed systems, void of any contamination and without loss of the parent element (C-14) or daughter element.
3. Known amounts of parent and daughter elements present from the beginning.
Assumption 1: Constant decay.
If the decay rate of C-14 were not always constant, then this would be devastating to the technique's credibility. Unfortunately, dating methods such as the carbon dating method have only been around for a short period of time. So far, no known environmental factors have been able to significantly cause the decay rates to vary. For this reason, I will have to bite the bullet and accept that it is reasonable to assume the decay rate is constant (even though I give this assumption, this doesn’t mean the decay rate is constant. Rather I am conceding due to no current evidence for the contrary). With this said, it would be worth while to check out this feedback session which does seem to suggest that there might have been an accelerated decay rate in the past, at least for the uranium-lead method. (Click)
Assumption 2: Closed systems.
“It is important to realize that an accurate radiometric date can be obtained only if the mineral remained a closed system during the entire period since its formation. A correct date is not possible unless there was neither the addition nor loss of parent or daughter isotopes.” 
This assumption is not one that I am willing to concede on. In order for carbon dating to work (and this applies to other dating methods as well), the parent and daughter concentrations must have not been altered throughout the specimen’s history. Common sense would seem to indicate that this is an unreasonable assumption, especially if carbon dating can be used to ‘date’ objects up to 50,000 years old. This would mean that for 50,000 years, the specimen that is being dated must have remained in a closed system for several thousand years. If that weren’t enough, the scientists dating the specimen must also be able to make the determination of whether or not the system has remained closed.
Assumption 3: Known amounts of daughter and parent element from the start.
This is another assumption that is often made, but rarely addressed. In order for the dates from C-14 to be accurate, the starting condition must be known. How do we know that the amount of C-14 in an organism that lived 5,000 years ago is the same amount that organisms have today?
Since it is assumed that an organism will have the same ratio of C-14 as found in the atmosphere, this is a point that must be taken into consideration also. According to Willard Libby (who invented the carbon dating method), if the influx of carbon-14 in the atmosphere were increasing at its current rate, then the atmosphere would reach equilibrium in about 20,000-30,000 years.* Evolutionists usually overlook this point because they believe the earth is around 4.55 billion years old. However, there are some studies that suggest that the C-14/C-12 ratio in the atmosphere has been increasing since the 1950s. Samples of historically known age can be used to estimate the amount of C-14 in the atmosphere at that point in time. Unfortunately, this only works for objects within the age of recorded history.
Another point to consider is the earth’s weakening magnetic field. In fact, the magnetic field of the earth loses about ½ of its strength every 1400 years. This indicates that the field was much stronger in the not too distant past. Since the magnetic field is responsible for deflecting radiation, less C-14 would have been formed during the time when the magnetic field was stronger. That means an organism that lived and died during a time when the magnetic field was stronger would have less C-14 to begin with. Such would make an organism look much older than it really is according to the carbon dating method. Evolutionists believe the reason the earth’s magnetic field appears to be weakening is because the field reverses itself. Even if this is true, it still doesn’t negate the fact that the magnetic field was stronger at some point, causing less C-14 to be formed in the atmosphere.
Have anomalous dates been known to occur?
Of course, no matter how well theories sound, the true test comes from actual experimentation. Answers In Genesis has reported of such a case where a piece of wood was found in the “Hawkesbury Sandstone” of Sydney, Australia. The Hawkesbury Sandstone has been assigned a geologic age of approx. 225-230 million years based on its position in the geologic column. It was doubtful if any detectable C-14 still remained in the wood, but a test was performed anyway to see if it contained C-14 (a sample of the wood was sent to Geochron Laboratories in Cambridge, Boston, USA). The wood came back with a C-14 age of 33, 720 ± 430 years! One might wonder if any contamination had occurred, but according to AIG, Geochron Laboratories conducted thorough tests to ensure that there was no contamination.
It has been said before that all evidence must be interpreted within a framework. Such a framework is the foundation in which we interpret our evidence upon. Starting with the Bible as our assumption, we must interpret the evidence based on a Biblical foundation. The Bible teaches the earth was covered in a watery cataclysm about 4,400 years ago. A global flood would have buried large pre-flood forests and animals. As a result of this, the flood buried large amounts of carbon. Animals that lived right after the flood may not have had as much carbon-14 available because of the global flood.
Also, many believe the Bible teaches that the earth was surrounded by a vapor canopy (otherwise known as the ‘canopy theory’). I’m not going to dogmatically say there was or wasn’t a vapor canopy. Well-known creationists seem to be split on this one. But, if there was a vapor canopy, then this extra layer of water would have helped filter out the sun’s radiation, and therefore, less C-14 would have be formed (if any).
Creationists have nothing to fear from carbon dating, as it does not disprove the young age of the earth. The carbon dating method is based largely on unverifiable assumptions that are made based upon one’s axioms. Most importantly, outside of known or recorded history, there is no way of verifying these old ages.
"If a C-14 date supports our theories, we put it in the main text. If it does not entirely contradict them, we put it in a footnote. And if it is completely 'out of date," we just drop it."
T. Save-Soderbergh and I.U. Olsson (Institute of Egyptology and Institute of Uppsala, Sweden), C-14 dating and Egyptian chronology in radiocarbon variations and absolute chronology, Proceedings of the twelfth Nobel Symposium, New York, 1970, p.35.
* Imagine you’re filling up a barrel full of water. You’re pouring the water into the barrel at a steady rate. The only problem is, the barrel has holes in the side. So, as you're pouring water into the barrel, it is also being leaked out of the barrel. Eventually you’ll reach a point where the water entering the barrel is leaking out just as fast. This is the stage we call ‘equilibrium’. Unless you decrease the amount of water leaking from the barrel, or increase the amount going in, the barrel will reach ‘equilibrium’. The same is true for the earth’s atmosphere. According to John Morris, the earth’s atmosphere will reach equilibrium in only 30,000 years. Because of this, most people who believe in long ages tend to assume the earth’s atmosphere is already in equilibrium.
1. Walt Brown, In the Beginning, 7th edition, Center for Scientific Creation, p. 244, 2001.
2. Edward J. Tarbuck & Frederick K. Lutgens, Earth 6th edition, Prentice Hall, p. 202, 1999.
3. Willard Libby, “Radiocarbon Dating”, Chicago Press, pp. 4-9, 1952.
4. John Roach, National Geographic News, “The Earth’s Magnetic Field is Failing”, Sep. 9, 2004, <http://news.nationalgeographic.com/news/2004/09/0909_040909_earthmagfield.html#main>.
5. Russell Humphreys, Impact No. 188, “The Mystery of the Earth’s Magnetic Field”, 1989,
6. John Roach, National Geographic News, “The Earth’s Magnetic Field is Failing”, Sep. 9, 2004 http://news.nationalgeographic.com/news/2004/09/0909_040909_earthmagfield.html#main>.
7. Andrew Snelling, Creation, Vol 21 Issue 3, “Dating dilemma: fossil wood in ‘ancient’ sandstone”, <http://www.answersingenesis.org/creation/v21/i3/fossilwood.asp>.