To radiocarbon date an organic material, a scientist can measure the ratio of remaining Carbon-14 to the unchanged Carbon-12 to see how long it has been since the materials source died. Advancing technology has allowed radiocarbon dating to become accurate to within just a few decades in many cases.

How reliable is carbon dating science?

Radiocarbon dating can easily establish that humans have been on the earth for over twenty thousand years, at least twice as long as creationists are willing to allow. They have their work cut out for them, however, because radiocarbon (C-14) dating is one of the most reliable of all the radiometric dating methods.