The CRYOspheric STudies of Atmospheric Trends in stratospherically and radiatively important gases (CRYOSTAT) will undertake the first combined measurements of virtually all significant Greenhouse gases (GHGs)(other than water vapour), ozone-depleting substances (ODSs), and related trace gases in contiguous firn and ice profiles, spanning as much as 200 years, from both the northern and southern polar ice caps. The dataset contains concentrations of isotopes (CH4, N20, CO, CO2, N20, SF6, CH3Br, halocarbons, and hydrocarbons) in firn, N2O concentrations in ice, ice core density, firn diffusivity, and weather measurements. CRYOSTAT is an evolution of the FIRETRACC/100 project, the data from which is also held at BADC.