Younger Dryas turbidites indicate increased storminess in the North Atlantic

The Younger Dryas (YD) stands as one of the most abrupt climatic perturbations during the last deglaciation, marked by rapid North Atlantic cooling and global environmental upheaval. While the associated changing ocean-atmosphere dynamics are widely documented, the cascading impacts of its climate instability on deep-sea sedimentation remain poorly constrained, partly due to limited continuous high-resolution records spanning the entire period. Here, we analyzed two sediment cores from the glacially influenced SW Grand Banks slope off Newfoundland, Eastern Canada, presenting well-preserved distinct sedimentary sequences formed by downslope and along-slope processes, respectively. Within a canyon at ∼1500 m water depth, a ∼ 3 m thick YD interval features fine-grained turbidites initiated at the YD onset, peaking at 7 events per century during mid-YD, and persisting throughout the episode. Outside the canyon, a complete typical contourite sequence characterized by reverse-to-normal grading was identified at ∼2600 m water depth. Regional comparisons indicate that neither sediment instability alone nor earthquakes likely dominated YD turbidity current triggering. Rather, shared downslope sediment sources but distinct along-slope transport signatures between the turbidites and contourites imply storm-driven cross-shelf sediment supply enhancement, based on which we propose that increased storm activity promoted sediment accumulation at canyon heads, preconditioning YD turbidity currents. A mid-YD weakening of the along-slope current provides new evidence of oceanic changes preceding atmospheric shifts. This study elucidates how YD climatic instability reconfigured glaciomarine sediment dispersal and underscores the importance of understanding abrupt millennial-scale events for forecasting future geohazards under climate change scenarios.