Observed column densities for H₂O, CO₂ and CH₃OH and their uncertainties as derived in Boogert et al. (2011) towards the background star 2MASS J18170957-0814136, shown in dark blue. We also plot the column densities predicted by three different models aiming to reproduce the observed CO₂ column density. Except the dust temperature, they all share the same physical parameters retrieved from Herschel data of the cold core L429-C (see text). Grey squares correspond to a model with the dust temperature computed with the parametrisation from (Hocuk et al. 2017) with T_dust = 6.6 K; cyan triangles correspond to a model with a fixed temperature of T_dust = 10.3 K, and red stars correspond to a dust temperature retrieved from Herschel data, with T_dust = 14 K.