Radio carbon dating facts
This is calculated through careful measurement of the residual activity (per gram C) remaining in a sample whose age is Unknown, compared with the activity present in Modern and Background samples. Thus 1950, is year 0 BP by convention in radiocarbon dating and is deemed to be the 'present'.You can get an idea of the relationship between C14 and age at the Carbon Dating calculator page. 1950 was chosen for no particular reason other than to honour the publication of the first radiocarbon dates calculated in December 1949 (Taylor, 19).
Obviously, this activity is additional and must be removed from calculations.Unfortunately, tree ring dating is itself not entirely reliable, especially the "long chronology" employed to calibrate the carbon dating method.The result is that carbon dating is accurate for only a few thousand years. This fact is born out in how carbon dating results are used by scientists in the scientific literature. Furthermore, the ratio is known to fluctuate significantly over relatively short periods of time (e.g. Unfortunately the ratio of carbon-12 to carbon-14 has yet to reach a state of equilibrium in our atmosphere; there is more carbon-14 in the air today than there was thousands of years ago.