This variation is caused by both natural processes and human activity. Cosmic rays and changes in Earth's climate can cause irregularities in the amount of. But new research shows that commonly accepted radiocarbon dating indicates that it's arguable their fundamental basis is faulty-they are.
Its presence in organic materials is the basis of the radiocarbon dating method. When an organism dies, the amount of 14C within the material slowly decreases at a known rate through radioactive decay relative to the non-radioactive, or stable, isotopes of carbon 12C and 13C in the material. As a result, measuring the proportion of radiocarbon remaining in the sample compared to amount it would have had when alive provides an objective method of determining the time ranges within which the organism died.