Scientists at the Lamont-Doherty Geological Laboratory of Columbia University at Palisades, N.

Y., reported today in the British journal Nature that some estimates of age based on carbon analyses were wrong by as much as 3,500 years.

Accuracy of radio carbon dating video

In order for carbon dating to be accurate, we must know what the ratio of carbon-12 to carbon-14 was in the environment in which our specimen lived during its lifetime.

during the industrial revolution more carbon-12 was being produced offsetting the ratio a bit).

Unfortunately, we aren't able to reliably date artifacts beyond several thousand years.

Scientists have tried to extend confidence in the carbon dating method further back in time by calibrating the method using tree ring dating.

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.

Since 1947, scientists have reckoned the ages of many old objects by measuring the amounts of radioactive carbon they contain.

New research shows, however, that some estimates based on carbon may have erred by thousands of years.

Example: wood found in a grave of known age by historically reliable documents is the standard for that time for the C14 content.

This standard content of C14 can then be used for wood not associated with a historically documented date.

by Helen Fryman Question: What about radiocarbon dating? Response: I asked several people who know about this field. (1.) C14 dating is very accurate for wood used up to about 4,000 years ago.