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This study focuses on Pleistocene–Holocene sediments from the Shatsky Rise (Ocean Drilling Program Site 1209B, NW Pacific Ocean). We quantify the contribution of calcite made by coccoliths in oceanic sediments, investigating the role of calcareous nannoplankton during the last 450 ka. Coccolith carbonate constitutes 60–90% of bulk carbonate. Coccolith carbonate accumulation rates (CARs) and CaCO3 fine fraction confirm that coccolithophores are major contributors to the carbonate export and accumulation. Primary productivity shows highest values from marine isotope stage (MIS) 12 to 8. Thereafter, although coccolith calcite content remains high, other sediment components, such as as foraminifera and biogenic opal, seem to be favored, perhaps related to an increase in fertilization by eolian dust. Our results demonstrate the important role of coccolithophore production and sedimentation on the regulation of ocean carbonate chemistry on time scales >1000–100 000 years. On glacial–interglacial scales, coccolithophore productivity could have affected deep‐water saturation by buffering deep‐sea CO2 through increased carbonate dissolution episodes. Spectral and wavelet analyses are consistent with CARs primarily driven by glacial–interglacial variability and obliquity‐controlled changes. Coccolith‐based paleoceanographic reconstructions allow us to establish that during the last 450 ka the mid‐latitudes of the NW Pacific are controlled by the dynamics of the El Niño Southern Oscillation perturbations and Boreal Monsoon system.

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Western boundary currents flow along the western edge of ocean basins, transporting vast amounts of heat and moisture from equatorial regions to higher latitudes. The Kuroshio Current (KC) and the Kuroshio Current Extension (KCE) is the western boundary current system of the North Pacific Subtropical Gyre (Figure 1). The KC originates from the westward-flowing North Equatorial Current and has an estimated volume transport of 23.7-25.0 Sverdrup (Sv; 1 Sv = 1 million cubic meters per second) (Ichikawa & Beardsley, 1993). The current flows past the Izu Ridge until it separates from the Japan coast at approximately 36°N, 141°E flowing east into the Pacific Ocean (Imawaki et al., 2013) where it becomes the KCE. Maximum transport volume of the KCE has been estimated to reach up to 130 Sv (Wijffels et al., 1998). Thus, the KCE jet alone provides massive amounts of heat and moisture for North Pacific midlatitude cyclones. By modifying the path and intensity of storm tracks, changes to the dynamic state of the KCE can alter the stability and pressure gradient within the local atmospheric layers and basin-scale wind stress patterns (Frankignoul & Sennechael, 2007;Kwon et al., 2010) which, in turn, influences atmospheric processes affecting precipitation patterns over Japan and the west coast of North America (Latif & Barnett, 1994).The KCE region is one of the most dynamic and important regions of the world's ocean. Meeting of subtropical water masses brought north by the KC with southward flowing subpolar waters by the Oyashio Current (Figure 1) creates a relatively steep temperature gradient across these currents in the northwest Pacific. This condition leads to annual average water temperatures differing by about 8°C from 35°N to 40°N across the KCE and Oyashio Current (Locarnini et al., 2013). Measurements of air-sea CO 2 fluxes over