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Observations of gradients in the total CO<sub>2</sub> column, ⟨CO<sub>2</sub>⟩, are expected to provide improved constraints on surface fluxes of CO<sub>2</sub>. Here we use a general circulation model with a variety of prescribed carbon fluxes to investigate how variations in ⟨CO<sub>2</sub>⟩ arise. On diurnal scales, variations are small and are forced by both local fluxes and advection. On seasonal scales, gradients are set by the north-south flux distribution. On synoptic scales, variations arise due to large-scale eddy-driven disturbances of the meridional gradient. In this case, because variations in ⟨CO<sub>2</sub>⟩ are tied to synoptic activity, significant correlations exist between ⟨CO<sub>2</sub>⟩ and dynamical tracers. We illustrate how such correlations can be used to describe the north-south gradients of ⟨CO<sub>2</sub>⟩ and the underlying fluxes on continental scales. These simulations suggest a novel analysis framework for using column observations in carbon cycle science.