An absorption-line blackbody distribution function for CO2 is presented which permits efficient and accurate calculation of total heat transfer rates. The model allows the local absorption coefficient to be the basic radiative property, permitting its use in arbitrary solution methods of the radiative transfer equation (RTE). A mathematical correlation is presented to approximate the function for use in computer codes. Total emissivities calculated with the correlation agree well with Hottel data. Excellent agreement is also demonstrated with line-by-line solutions of the RTE.