How do I report radiocarbon dates?
Radiocarbon dates should always be reported either as `percent modern or years `before present (BP). The first indicates the proportion of radiocarbon atoms in the sample as compared to samples modern in 1950.
Why are radiocarbon dates calibrated?
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.