Thus, as millions of tons of Carbon are pushed into the atmosphere, the steady ratio of these two isotopes is being disrupted. Most 14C is produced in the upper atmosphere where neutrons, which are produced by cosmic rays , react with 14N atoms. Radiocarbon dating is used in many fields to learn information about the past conditions of organisms and the environments present on Earth.
Radiocarbon dating is therefore limited to objects that are younger than 50, to 60, years or so. Quaternary Science Reviews, 32 0 : Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes.