Ingmar Nitze , Konrad Heidler, Nina Nesterova, Jonas Küpper, Emma Schütt, Tobias Hölzer, Sophia Barth, Mark Lara, Anna K Liljedahl, Guido Grosse

Retrogressive Thaw Slumps (RTS) and Active Layer Detachment Slides (ALD) are widespread thermal mass-wasting hillslope failures triggered by thawing permafrost. Despite increasing rates of these failures, knowledge about their pan-arctic spatial and temporal distribution remains limited. We present the Database of AI-detected Arctic RTS and ALD footprints (DARTS), the largest hillslope thermokarst database with over 43,000 individual features. which spans approximately 1.6 million km² for 2018 to 2023 and at least annual coverage in 2021 to 2023 for a ~900,000 km² region. DARTS is freely available in two processing levels: sub-annual and annually aggregated polygon footprints. The database was created with a fully automated workflow that leverages deep learning-based segmentation of PlanetScope multi-spectral imagery (3-5m spatial resolution) with minimum annual coverage. We validated DARTS using different datasets, achieving F1 scores ranging from 0 to 0.519, with more accurate results in RTS-rich areas. The DARTS database will be valuable for mapping, quantifying, and understanding hillslope thermokarst distribution and change over time across the circum-arctic permafrost region.