Hello All,
I was told of a journal article discussing the isotope ratio of carbon in the atmosphere. Supposedly, the article links the increased atmospheric CO2 concentration to anthropogenic sources through this carbon isotope ratio. 
Unfortunately, after a couple of weeks of looking for this article, I have been unable to find it. Has anyone else come across such an article? Either my searching technique is really lacking, or it doesn't exist (the article).
Thanks,
-Tom Millican


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University of Arkansas Stable Isotope Laboratory
http://www.uark.edu/ua/isotope/