Cosmic molecular gas mass density evolution measured from ALMACAL-22 in purple. The right y axis represents the unitless density parameter for molecular gas, Ω_H2 = ρ_H2/ρ_{crit, z = 0}. For comparison, we include estimates from other surveys: COLDz (Riechers et al. 2020a), ASPECS CO (Decarli et al. 2020) and dust measurements (Magnelli et al. 2020), PHIBSS (Lenkić et al. 2020), VLASPECS (Riechers et al. 2020a), HDF-N+ASPECS-LP (Boogaard et al. 2023), xCOLD GASS (Saintonge et al. 2017; Fletcher et al. 2021), ALMACAL in absorption (Klitsch et al. 2019b), ALMACAL-22 adopting the lowest-J approach (this work, see Sect. 4.5), from the K-band of the Herschel Reference Survey (HRS) (Andreani et al. 2020), A³COSMOS (Liu et al. 2019), other estimates from dust continuum (Scoville et al. 2017; Berta et al. 2013), and from recent works reporting over-densities at z ∼ 2 in the Spiderweb galaxy protocluster (Jin et al. 2021) and at z ∼ 3 in the MUSE Quasar Nebula 01 (MQN01) field (Pensabene et al. 2024). We plot consistent estimates scaled to the same cosmology (H₀) used in this work and without helium contribution. We find overall consistency with the trend reported by other blind surveys, although slightly lower values are found at high redshift (z > 1).