The diminishing levels via decay means that the effective limit for using c14 to estimate time is about 50,000 years. After this time, there is little if any c14 left. Subsequent work has shown that the half-life of radiocarbon is actually 5730 ± 40 years, a difference of 3% compared to the Libby half-life.

What happens to carbon-14 when it decays?

Carbon-14 is a rare version of carbon with eight neutrons. It is radioactive and decays over time. When carbon-14 decays, a neutron turns into a proton and it loses an electron to become nitrogen-14. The length of time it will take for half the amount of carbon-14 to decay is known as its half-life.