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Proactive disclosure Print version   | |  Radiocarbon Dating Ambient Levels The Geological Survey of Canada Radiocarbon Dating Laboratory ceased operation at the end of 2005. This site will be maintained to provide reference information on the samples dated during the 45 years of operation of the GSC laboratory from 1960 to 2005. Ambient C-14 Levels Carbon has one naturally occurring radioisotope, C-14, which is continually produced in the upper atmosphere (stratosphere) by cosmic rays. This radioactive carbon is rapidly oxidized to CO2 and mixes with the nonradioactive CO2 in the lower atmosphere (troposphere). The breakdown of this naturally occurring C-14 allows the dating of carbonaceous materials. All radiocarbon dates are related to the 1950 (prebomb) activity of C-14 (Modern Carbon). Unfortunately, bomb-generated C-14 undergoes the same fate as naturally occurring C-14 and is integrated into the global carbon cycle. Thirty years of environmental data was published in 1994 as environmental monitoring data [PDF, 294.7 kb, viewer] McNeely, R. The table of 1960 to 1994 data has been updated to 2004 and is available as an EXCEL file.
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