Submergence influences higher shoreline retreat rates in complex low-lying tundra coasts (Tuktoyaktuk Peninsula, NWT, Canada)

This study assesses shoreline change dynamics in the Tuktoyaktuk Peninsula, Beaufort Sea (Canada), using aerial photography-derived orthomosaics (1950, 1985) and very high-resolution Pléiades satellite (2020) imagery. We (1) characterised backshore and foreshore morphologies, (2) analysed spatiotemporal shoreline change rates, and (3) identified the morphology influence on shoreline evolution. The average shoreline change rate was -0.77 m/yr , with a 31% increase since 1985, affecting 57% of the area. Shoreline retreat affected at least 83% of the shoreline in each sector, with the highest rates in the central sectors of the peninsula. Coastal morphology was the main factor influencing spatial variability and the dominant shoreline retreat processes. Tundra flats showed the highest retreat rates in backshore and foreshore, displaying the highest rates and 38% of land loss, despite covering 29% of the peninsula. These results challenge erosion-centric models of Arctic coastal change, highlighting submergence as a dominant process in low-lying coasts. The erosion-submergence distinction is critical for improving predictive models and adaptation strategies in vulnerable communities like Tuktoyaktuk. Future research must integrate subsidence measurements, sea-level rise, inundation impacts and coastal morphology to address gaps in shoreline change models and impacts on Arctic coastal systems.