Molecular gas depletion timescale as a function of redshift for our compilation of CO-detected MS SFGs from the literature (Dessauges-Zavadsky et al. 2015) and MACSJ0032-arc at z_CO = 3.6314 (star). The encircled data points correspond to MS SFGs with measured gas-phase metallicities. Five redshift bins are considered: z ~ 0, z = [ 0.055,0.4 ], z = [ 1,1.6 ], z = [ 2,2.5 ], and z = [ 2.7,3.6 ]. The corresponding mean values of t_depl are shown as large black crosses with the associated 1σ dispersion as standard deviation. Magenta crosses represent t_depl values from Béthermin et al. (2015) derived from the FIR dust continuum and by adopting the same mass-metallicity relation (Eq. (4)). The observed evolution of t_depl with redshift is parametrized by a power law; the best fit, 1.15(1 + z)^-0.85, is shown as a solid line.