[1] The Bering Sea gateway between the Pacific and Arctic oceans impacts global climate when glacialinterglacial shifts in shore line position and ice coverage change regional albedo. Previous work has shown that during the last glacial termination and into the Holocene, sea level rises and sea ice coverage diminishes from perennial to absent. Yet, existing work has not quantified sea ice duration or sea surface temperatures (SST) during this transition. Here we combine diatom assemblages with the first alkenone record from the Bering Sea to provide a semiquantitative record of sea ice duration, SST, and productivity change since the Last Glacial Maximum (LGM). During the LGM, diatom assemblages indicate that sea ice covered the southeastern Bering Sea perennially. At 15.1 cal ka B.P., the diatom assemblage shifts to one more characteristic of seasonal sea ice and alkenones occur in the sediments in low concentrations. Deglaciation is characterized by laminated intervals with highly productive and diverse diatom assemblages and inferred high coccolithophorid production. At 11.3 cal ka B.P. the diatom assemblage shifts from one dominated by sea ice species to one dominated by a warmer water, North Pacific species. Simultaneously, the SST increases by 3°C and the southeastern Bering Sea becomes ice-free year-round. Productivity and temperature proxies are positively correlated with independently dated records from elsewhere in the Bering Sea, the Sea of Okhotsk, and the North Pacific, indicating that productivity and SST changes are coeval across the region.

The uncertain response of marine terminating outlet glaciers to climate change at time scales beyond short-term observation limits models of future sea level rise. At temperate tidewater margins, abundant subglacial meltwater forms morainal banks (marine shoals) or ice-contact deltas that reduce water depth, stabilizing grounding lines and slowing or reversing glacial retreat. Here we present a radiocarbon-dated record from Integrated Ocean Drilling Program (IODP) Site U1421 that tracks the terminus of the largest Alaskan Cordilleran Ice Sheet outlet glacier during Last Glacial Maximum climate transitions. Sedimentation rates, ice-rafted debris, and microfossil and biogeochemical proxies, show repeated abrupt collapses and slow advances typical of the tidewater glacier cycle observed in modern systems. When global sea level rise exceeded the local rate of bank building, the cycle of readvances stopped leading to irreversible retreat. These results support theory that suggests sediment dynamics can control tidewater terminus position on an open shelf under temperate conditions delaying climate-driven retreat.

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Post‐glacial sea level rise led to a direct connection between the Arctic and Pacific Oceans via the Bering Strait. Consequently, the Bering Sea experienced changes in connectivity, size, and sediment sources that were among the most drastic of any ocean basin in the past 30,000 years. However, the sedimentary response to the interplay between climate change and sea level rise in high‐latitude settings such as Beringia remains poorly resolved. To ascertain changes in sediment delivery, productivity, and regional oceanography from the Last Glacial Maximum (LGM) to the Holocene, we analyzed sedimentological, geochemical, and isotopic characteristics of three sediment cores from the Bering Sea. Interpretations of productivity, terrestrial input, nutrient utilization, and circulation are based on organic carbon isotopes (δ13Corg), total organic carbon (TOC), bulk nitrogen isotopes, total organic nitrogen, carbon/nitrogen ratios, elemental X‐ray fluorescence data, grain size, and presence of laminated or dysoxic, green intervals. Principal component analysis of these data captures key climatic intervals. The LGM was characterized by low productivity across the region. In the Bering Sea, deglaciation began around 18–17 ka, with increasing terrestrial sediment and TOC input. Marine productivity increased during the Bølling‐Allerød when laminated sediments revealed dysoxic bottom waters where denitrification was extreme. The Younger Dryas manifested increased terrestrial input and decreased productivity, in contrast with the Pre‐Boreal, when productivity markedly rebounded. The Pre‐Boreal and Bølling‐Allerød were similarly productive, but changes in the source of TOC and a δ13Corg depletion suggest the influence of a gradually flooding Bering Shelf during the Pre‐Boreal and Holocene.

Deglacial sea surface conditions in the subarctic North Pacific and marginal seas are the subject of increasing interest in paleoceanography. However, a cohesive picture of near-surface oceanography from which to compare inter and intra-regional variability through the last deglaciation is lacking. We present a synthesis of sea surface temperature covering the open North Pacific and its marginal seas, spanning the past 20 ka using proxy records from foraminiferal calcite (δ18O and Mg/Ca) and coccolithophore alkenones (Uk'37). Sea surface temperature proxies tend to be in agreement through the Holocene, though Uk'37 records are often interpreted as warmer than adjacent δ18O or Mg/Ca records during the Last Glacial Maximum and early deglaciation. In the Sea of Okhotsk, Holocene discrepancies between δ18O and Uk'37 may be the result of changes in near-surface stratification. We find that sea-surface warming occurred prior to the onset of the Bølling-Allerød (14.7 ka) and coincident with the onset of the Holocene (11.7 ka) in much of the North Pacific and Bering Sea. Proxy records also show a cold reversal roughly synchronous with the Younger Dryas (12.9-11.7 ka). After the onset of the Holocene, the influence of an intensified warm Kuroshio Current is evident at higher latitudes in the Western Pacific, and an east-west seesaw in sea surface temperature, likely driven by changes in the strength of the North Pacific Gyre, characterizes the open interglacial North Pacific.