Atom used in radiocarbon dating
This can be overcome by calibration curves calculated by dating materials of precisely known age.
The best samples are tree rings, but annually laminated sediments have also produced excellent results. Chudy, Eristavi, Pagva, Povinec, Sivo, and Togonidze. Anthropogenic 14C variations in atmospheric CO2 and wines.
Therefore, radiocarbon dates are calculated to a "pre-bomb" age of 1950 A. Material which died after 1950 has such high amounts of radiocarbon its age is reported as "percent modern (1950)" (example 180% modern).
This bomb radiocarbon has been gradually removed from the atmosphere by by natural processes, but the "bomb spike" can be shown through the dating by means such as comparing the bottle date and radiocarbon age of wines.
In fact, the natural production of radiocarbon has varied as well.
Before the industrial revolution, from 1800 - 1400 AD, the natural production of radiocarbon was high, so dates are "too young." From 1400 AD to 300 BC they are "too old," and prior to 300 BC , they are too young.
Carbon atoms are incorporated into plant tissue (by photosynthesis) then into animal tissue (by ingestion) in nearly the same ratio as in the atmosphere. The Earth's magnetic field, its history, origin and planetary perspective.
3.5 decays/gram/minute of carbon would be produced by a sample 11,460 years old.