A competing transport mode to the surface transport is direct or effusive transport, where a gas molecule impinges on the pores directly from the gas phase (Figure , ii). For small pores, there is no consensus in the literature on the extent of direct versus surface transport. It is convenient to model CO2 transport by assuming direct transport, where the transport rate can be calculated by adding an energy barrier term to the effusive transport rates (modified effusion model). We show that CO2 primarily transports via the surface transport mechanism. For this, the contribution of direct and surface flux to the overall transport rate is quantified. Tracking the path of CO2 in the MD simulation, we find that surface flux overwhelmingly dominates CO2 transport, with 99% of translocation events taking place by surface pathway at room temperature. Even at elevated temperatures (e.g., 423 K), surface flux contributes 90% of the total translocation events.