Northern hemisphere permafrost loss documented through ESA CCI+ Permafrost climate data records

The objective of the European Space Agency Climate Change Initiative (ESA CCI+) Permafrost project is to develop and deliver permafrost data as Essential Climate Variable (ECV) products primarily derived from satellite measurements (https://climate.esa.int/en/projects/permafrost/). The required associated parameters by the Global Climate Observation System (GCOS) for the ECV Permafrost are 'permafrost temperature' and 'active layer thickness'. Further on, permafrost extent (as a derivative of ground temperature) needs to be quantified.Algorithms were identified which can provide these parameters of interest by ingesting a set of global satellite data products (land surface temperature and land cover), re-analysis data (snow-water equivalent) and subsurface stratigraphy in a permafrost model scheme that computes the ground thermal regime.The resulting datasets are annual products of mean annual ground temperature (MAGT) at different depths, active layer thickness (maximum thaw depth) and permafrost fraction (based on MAGT at 2m depth) from 1997 to 2023.The estimated reduction of permafrost extent in the timeframe from 1997 to 2023 was 8%. The mean annual ground temperature at 2m depth has increased from approximately -2°C to -1°C (within maximum permafrost extent of the observation period). The thickness of the active layer has increased by 30 cm on average. Distinct regional differences can be observed which will be presented.