Likewise, different living things absorb or reject carbon-14 at different rates.Two plants that died at the same moment, but which naturally contained different levels of radiocarbon, could be dated to drastically different times.When an organism dies, it stops taking in new carbon-14, and whatever is inside gradually decays into other elements.Carbon-14 normally makes up about 1 trillionth (1/1,000,000,000,000) of the earth’s atmosphere.In short, carbon dating is as useful as any other technique, so long as it’s done properly and the results are objectively interpreted.It is not, however, an inherently error-free or black-and-white method for dating objects.
This is perhaps the greatest point of potential error, as assumptions about dating can lead to circular reasoning, or choosing confirming results, rather than accepting a “wrong” date.
The other major factor affecting the results of carbon dating is gauging the original proportion of carbon-14 itself.
Carbon dating is based on the loss of carbon-14, so, even if the present amount in a specimen can be detected accurately, we must still know how much carbon-14 the organism started with.
Contamination and repeatability are also factors that have to be considered with carbon dating.
A tiny amount of carbon contamination will greatly skew test results, so sample preparation is critical.