| Abstract: | In the last 4 years we have witnessed a surge of measurements of the gas content in galaxies at increasing redshifts. This wave has been driven by new and upgraded instruments in the far-infrared and sub-millimeter that are able to perform such measurements in z>0.5 galaxies. CO observations receive special attention these days as ALMA enters routine operation phase. But does CO emission trace all the molecular gas? I will present the state of current molecular gas measurements up to z=3 and discuss the structure of molecular clouds and the so called 'dark gas' that we may(?) be missing. |
