Coupled Impacts of Atmospheric Circulation and Sea‐Ice on Late Pleistocene Terrigenous Sediment Dynamics in the Subarctic Pacific Ocean.

Processes controlling environmental change in the subarctic Pacific Ocean on millennial to orbital timescales are not well understood. Here we use a 230‐kyr sedimentary record from the northwest Pacific Ocean to assess the response of late Pleistocene sediment dynamics to orbital forcing. Combining a source‐to‐sink perspective based on sedimentological records with climate model reanalysis, we reveal that fluctuations in sediment provenance were closely linked to obliquity‐forced changes in atmospheric circulation modes. Specifically, the position of the Aleutian Low controlled sediment transport from the Bering Sea and Aleutian Arc sources. Furthermore, a distinct shift in North Pacific ocean circulation during the Last Glacial Maximum may have been related to a strengthened Siberian High. The coincidence of atmospheric mode switches with changes in sea‐ice extent and North Pacific Intermediate Water formation in the marginal seas suggests that this coupled ocean‐atmosphere system may have acted as a regional amplifier of global climate variability. Plain Language Summary: We use a sedimentary record from the northwest Pacific Ocean to assess the sensitivity of regional sediment transport dynamics to orbital forcing over the last 230 thousand years. By combining the sedimentological records with climate model simulations, we suggest that changes in sediment transport could have resulted from obliquity‐scale changes in atmospheric climatic modes, and specifically the position of the Aleutian Low. Moreover, we found a shift in the location of intermediate water formation during the Last Glacial Maximum, which may have been related to a strengthened Siberian High. This coupled ocean‐atmosphere system represents a potential amplifier of climate variability, such that improved constraints on its past behavior could provide insight into how climatic signals are transferred between regional and global scales. Key Points: Source‐to‐sink studies in the subarctic Pacific Ocean based on geochemical, clay mineralogic and environmental magnetic proxiesThe glacial/interglacial transition can be interpreted to be resulted from atmospheric climatic modes induced by Aleutian low‐forcingThis ocean‐atmosphere response is an amplifying feedback mechanism within the climate system [ABSTRACT FROM AUTHOR]