We can only make assumptions about past atmospheric carbon nuclide regimes, which introduces a significant unknown variable.
Dendrochronology has documented major variations in past carbon regimes. The decay rate is expressed in the half-life of radioactive substances.
The corruption imposed on the first meaning becomes apparent when the term is used in the second meaning but the precision implicit in the first meaning is often attributed to such usage.
Significant problems also arise when the scientific (i.e.
For instance, it is commonly assumed that charcoal excavated in sediment strata provides secure dating for such deposits.