Evidence for Submarine Landslides at Climate Transitions in a High Arctic Fjord (Grise Fiord, Nunavut)

Abstract

Arctic fjords are experiencing rapid environmental change driven by amplified high‐latitude warming, with implications for submarine slope stability. This study investigates the distribution, timing and triggering mechanisms of submarine landslides in Grise Fiord (High Arctic) to evaluate the role of past climate variability in sediment preconditioning and slope failure. High‐resolution multibeam bathymetry and sub‐bottom profiler data were combined with a multiproxy analysis of sediment cores, including physical properties, dinoflagellate cyst assemblages and geochemistry. Bathymetric mapping reveals more than 100 submarine landslides throughout the fjord, with morphologies indicating triggering by deltaic progradation, iceberg groundings and the downslope extension of subaerial debris flows. Core stratigraphy and acoustic backscatter data suggest that these slope failures are not modern, having occurred more than 1000 years ago. Available chronologies on three of the submarine landslides suggest that they were initiated during transitions from colder to warmer climatic conditions, pointing to a climatic control on slope instability, potentially linked to reduced sea‐ice cover and increased meltwater and sediment delivery. These findings contrast with lower latitude fjords on southern Baffin Island, where modern submarine landslides are already occurring, highlighting a spatial lag in geomorphic response to Arctic warming. Grise Fiord may therefore represent a fjord system in a preinstability state, with modern slope failures likely to emerge once climatic thresholds similar to those in southern Baffin Island are reached. Continued warming underscores the need for monitoring, particularly given implications for future coastal and port infrastructure in Ausuittuq.