Kinetic temperature as a function of CO column density obtained using the Meudon PDR code. The solid, dashed, and dotted lines depict models with thermal pressures of 10⁴, 10⁵, and 10⁶ cm⁻³ K, respectively, while pink, red, and green correspond to metallicities (relative to solar) Z = 0.2, 0.5, and 1, respectively. The blue (log T_K[k] = 1.2 ± 0.1) and orange (log T_K[k] = 1.7 ± 0.3) horizontal stripes show our choice of priors on the kinetic temperatures used to fit CO absorption lines towards sightlines with and without CO detections, respectively.