Calibration of radiocarbon results is needed to account for changes in the atmospheric concentration of carbon-14 over time. These changes were brought about by several factors including, but not limited to, fluctuations in the earths geomagnetic moment, fossil fuel burning, and nuclear testing.

What does calibration mean in Archaeology?

Radiocarbon dating measurements produce ages in radiocarbon years, which must be converted to calendar ages by a process called calibration. Calibration is needed because the atmospheric 14. C/ 12. C ratio, which is a key element in calculating radiocarbon ages, has not been constant historically.