When carbon-14 decays, the decay products are nitrogen-14 and an electron (and an electron antineutrino, but that's chemically irrelevant):

$\ce{^{14}_6C \rightarrow ^{14}_7N + e^- + \overline{v_e}}$

Let's assume that the carbon atom in question is part of a carbon dioxide molecule in the atmosphere. What would happen to the molecule when the atom decays into nitrogen? Will it be converted into a $\ce{NO_2}$ molecule, or will it split apart? Will the electron created in the decay have sufficient energy to escape the molecule and form a positive ion?

EDIT: Here's a somewhat related question dealing with the formation of radioactive carbon dioxide.