Specimens which lived and died during a period of intense volcanism would appear older than they really are if they were dated using this technique.
The ratio can further be affected by C-14 production rates in the atmosphere, which in turn is affected by the amount of cosmic rays penetrating the earth's atmosphere.
The amount of cosmic rays penetrating the earth's atmosphere is itself affected by things like the earth's magnetic field which deflects cosmic rays.
Precise measurements taken over the last 140 years have shown a steady decay in the strength of the earth's magnetic field.
So, if we find the remains of a dead creature whose C-12 to C-14 ratio is half of what it's supposed to be (that is, one C-14 atom for every two trillion C-12 atoms instead of one in every trillion) we can assume the creature has been dead for about 5,730 years (since half of the radiocarbon is missing, it takes about 5,730 years for half of it to decay back into nitrogen).
If the ratio is a quarter of what it should be (one in every four trillion) we can assume the creature has been dead for 11,460 year (two half-lives).
Plants and animals naturally incorporate both the abundant C-12 isotope and the much rarer radiocarbon isotope into their tissues in about the same proportions as the two occur in the atmosphere during their lifetimes.
uninformed claim that ' Dr Austin carefully designed the research to counter all possible objections', Austin clearly demonstrated his inexperience in geochronology when he wasted a lot of money using the K-Ar method on the wrong type of samples.
This man-made fluctuation wasn't a natural occurrence, but it demonstrates the fact that fluctuation is possible and that a period of natural upheaval upon the earth could greatly affect the ratio.
Volcanoes spew out CO which could just as effectively decrease the ratio.
It is naturally unstable and so it will spontaneously decay back into N-14 after a period of time.
It takes about 5,730 years for half of a sample of radiocarbon to decay back into nitrogen.
Search for carbindating:
First of all, it's predicated upon a set of questionable assumptions.