Impact of the Western Pacific Warm pool and Kuroshio dynamics in the Okinawa Trough during the Holocene.

The integrated effects of the Western Pacific Warm Pool (WPWP) and the Kuroshio Current (KC) on the thermal evolution of the subtropical northwestern Pacific during the Holocene have remained elusive. This study presents new δ18O and Mg/Ca ratio records of subsurface-dwelling planktonic foraminifera Pulleniatina obliquiloculata at Site A7 in the Okinawa Trough to reconstruct thermocline-water evolution since the last deglaciation (∼18 ka) and further explore the effects of the WPWP and the KC dynamics throughout the Holocene. The Mg/Ca-based thermocline-water temperature (TWT) record displays a long-term cooling trend of ∼3 °C since the middle Holocene (∼7 ka), with a similar trend with that in the WPWP. Furthermore, two major thermocline warming events occurred with an amplitude of ∼2–3 °C in the early (∼11.8–9.5 ka) and middle (∼8–6.5 ka) Holocene, respectively. Both events are comparable with those in the WPWP. Besides, our TWT record had nine Holocene rapid cooling events with amplitudes of ∼1–2 °C around 1.7, 3.2, 4.4, 6.0, 7.2, 7.5, 8.2, 8.9, and 10 ka, respectively. The cooling events were also identified in the temperature records of the thermocline and/or intermediate waters in the WPWP within the chronological uncertainties. The comparability of these temperature records between both regions reveals that the dynamic KC transmitted thermal signals of the WPWP thermocline/intermediate waters into the Okinawa Trough on centennial to multi-millennial timescales, highlighting a crucial role of the WPWP in influencing subtropical ocean thermodynamics and climate in the Holocene. • Thermocline temperature record was reconstructed in the Okinawa Trough since 18 ka. • A mid- to late Holocene thermocline cooling trend and two major EH & MH thermocline warming events in the Okinawa Trough. • Thermal signals of the WPWP were transmitted by the KC on centennial to multi-millennial timescales in the Holocene. [ABSTRACT FROM AUTHOR]