When I read about carbon sinks and the production of CO2, I am puzzled by the trust we have in carbon dating. If I understand correctly, C14 is produced by cosmic rays and nitrogen and is considered a very steady process thus carbon dating is trusted. But if C14 is brought into biological systems as a percentage of C14 in the atmosphere, why does the C14 percentage not change with atmospheric CO2 levels and thus give conflicting dating information. If CO2 levels have doubled in the last several hundred years, is the C14 level not half of what it would have been? Do I misunderstand how C14 is incorporated into biological systems? Is there some mechanism in the biosphere that keeps a steady ratio of C12 to C14? Once the C14 is captured, the whole thing makes sense but I do not see how the capture can be steady over time.