Nuclear tests, nuclear reactors and the use of nuclear weapons have also changed the composition of radioisotopes in the air over the last few decades.
This human nuclear activity will make precise dating of fossils from our lifetime very difficult due to contamination of the normal radioisotope composition of the earth with addition artificially produced radioactive atoms.
Carbon dating cannot be used on most fossils, not only because they are almost always allegedly too old, but also because they rarely contain the original carbon of the organism that has been fossilized.
Also, many fossils are contaminated with carbon from the environment during collection or preservation procedures.
The mathematical premise undergirding the use of these elements in radiometric dating contains the similar confounding factors that we find in carbon-14 dating method.
Most scientists today believe that life has existed on the earth for billions of years.
All dating methods that support this theory are embraced, while any evidence to the contrary, e.g. Prior to radiometric dating, evolution scientists used index fossils a.k.a. A paleontologist would take the discovered fossil to a geologist who would ask the paleontologist what other fossils (searching for an index fossil) were found near their discovery.
Scientists attempt to check the accuracy of carbon dating by comparing carbon dating data to data from other dating methods.
Other methods scientists use include counting rock layers and tree rings.
When scientists first began to compare carbon dating data to data from tree rings, they found carbon dating provided "too-young" estimates of artifact age.
Scientists now realize that production of carbon-14 has not been constant over the years, but has changed as the radiation from the sun has fluctuated.