Sea surface temperature variability and sea‐ice extent in the subarctic northwest Pacific during the past 15,000 years

Abstract

[1] Past changes in North Pacific sea surface temperatures and sea-ice conditions are proposed to play a crucial role in deglacial climate development and ocean circulation but are less well known than from the North Atlantic. Here, we present new alkenone-based sea surface temperature records from the subarctic northwest Pacific and its marginal seas (Bering Sea and Sea of Okhotsk) for the time interval of the last 15 kyr, indicating millennial-scale sea surface temperature fluctuations similar to short-term deglacial climate oscillations known from Greenland ice core records. Past changes in sea-ice distribution are derived from relative percentage of specific diatom groups and qualitative assessment of the IP 25 biomarker related to sea-ice diatoms. The deglacial variability in sea-ice extent matches the sea surface temperature fluctuations. These fluctuations suggest a linkage to deglacial variations in Atlantic meridional overturning circulation and a close atmospheric coupling between the North Pacific and North Atlantic. During the Holocene the subarctic North Pacific is marked by complex sea surface temperature trends, which do not support the hypothesis of a Holocene seesaw in temperature development between the North Atlantic and the North Pacific.

Sediment provenance variations in the southern Okhotsk Sea over the last 180 ka: Evidence from light and heavy minerals

“…The contents of both IP 25 (highly branched isoprenoid sea ice biomarker) and diatom species (sea ice and open water) in core SO201-2-12 located at the East Kamchatka Peninsula (Fig. 1) suggest a resembled seasonal sea ice coverage between H1 and YD (Méheust et al, 2016;Max et al, 2012). Therefore, it is reasonable to speculate that detrital materials entrained in sea ice on east Kamchatka Peninsula most probably is transported to the southern Okhotsk Sea by the Kamchatka Current during MIS 6.…”

Pulses of enhanced North Pacific Intermediate Water ventilation from the Okhotsk Sea and Bering Sea during the last deglaciation

“…The physical mechanism behind this effect is the positive feedback between salinity anomalies and ocean circulation known as Stommel feedback (Saenko et al, 2004). In contrast, sea surface temperature (SST) records from the northwest Pacific suggest no shift in poleward oceanic heat transport during these intervals Max et al, 2012). Hence, the role of the PMOC in destabilizing the density-driven stratification by buffering the decrease in poleward global oceanic heat transport and associated larger northward advection of saline subtropical waters into the subarctic Pacific during HS-1 and the YD seems to have been overestimated by model simulations.…”

“…1) is presented in detail in Max et al (2012). These records are part of a stratigraphic framework for the subarctic northwest Pacific and its marginal seas (Riethdorf et al, 2013).…”

“…3). Beyond this depth, the δ 13 C DIC values rapidly decline to −0.6 to Red lines indicate correlation points to the established stratigraphy of Okhotsk Sea record LV29-114-3 and high-resolution sediment core SO201-2-12KL from the subarctic northwest Pacific (Max et al, 2012). Given are the Ca-intensity records achieved from core logging (XRF) together with raw AMS 14 C datings (red spots with vertical numbers).…”

“…Radiocarbon ages are given according to the convention outlined by Stuiver and Polach (1977) and Stuiver (1980) and summarized in Table 2. We applied reservoir age correction of +900 yr (Max et al, 2012) for core SO178-13-6, which is determined by a marine global average reservoir age correction of +400 yr (Reimer et al, 2013) and a local planktic reservoir age correction ( R) of +500 yr reported for the Okhotsk Sea environment (Kuzmin et al, 2001(Kuzmin et al, , 2007. There is increasing evidence that surface reservoir ages could have varied over the course of the last 20 kyr, due to global thermohaline reorganizations as well as changes in upper-ocean stratification.…”