Another claim is that the inconsistency of C levels in the atmosphere over the past 60,000 years creates a validity issue.
However, calibration of carbon levels using tree rings and other sources keep these effects to an extremely small level.
Carbon dating, like other radiometric dating methods, requires certain assumptions that cannot be scientifically proved.
These include the starting conditions, the constancy of the rate of decay, and that no material has left or entered the sample.
Beyond that timespan, the amount of the original C formed by irradiation of nitrogen by neutrons from the spontaneous fission of uranium, present in trace quantities almost everywhere.For these samples, other dating methods must be used.