The Permafrost CCI project is establishing Earth Observation (EO) based products for the permafrost Essential Climate Variable (ECV) spanning the last two decades. Since ground temperature and thaw depth cannot be directly observed from space-borne sensors, a variety of satellite and reanalysis data are combined in a ground thermal model. The algorithm uses remotely sensed data sets of Land Surface Temperature (MODIS LST/ ESA LST CCI) and landcover (ESA LandcoverCCI) to drive the transient permafrost model CryoGrid 2, which yields thaw depth and ground temperature at various depths, while ground temperature forms the basis for permafrost fraction.