Evidence of Southern Ocean influence into the far Northwest Pacific (Northern Emperor Rise) since the Bølling–Allerød warming

Abstract

The role of the Southern Ocean in releasing CO 2 (sequestered in the global ocean during the Last Glacial Maximum) into the atmosphere during deglaciation is an important topic for investigation of Earth's climate. Changes in global deep water circulation associated with upwelling of Circumpolar Deep Water (CDW) around Antarctica may have played a part in the CO 2 release, but remain poorly studied. The potential response of the Pacific Ocean, including the North Pacific, to upwelling of CDW with its vast reservoir of CO 2 remains unresolved. Here we combine productivity proxies, oxygen and carbon isotope values in benthic and planktic foraminifera, data on the occurrence and abundance of ice-rafted debris, and benthic foraminiferal species composition in three sediment cores with published data for three cores from the Northern Emperor Rise for the Last Glacial Maximum, deglaciation and Holocene in order to elucidate the North Pacific role in CO 2 redistribution in the past. Age models of the cores are based on radiocarbon data calibrated by 14 C atmospheric plateau tuning. The calcium carbonate content in all cores increased abruptly around 14.5 ka, indicating an influx of relatively young water enriched in carbonate ion, oxygen and nutrients, and sourced in the Southern Oceans. A decrease in the extent of sea ice at the NER area during early deglaciation is reflected in sharp increases in the productivity of siliceous phytoplankton near the onset of Bølling/Allerød warming, possibly facilitated by the influx of Southern Ocean-sourced nutrient-rich waters. • Stable isotope, lithological and micropaleontological proxies of 6 cores from the Western Subarctic Gyre (WSG) were studied. • Age models of cores over the last 25kyr were modified by radiocarbon data calibrated by 14C atmospheric plateau tuning. • Multiple lines of evidences support abrupt flushing of Southern Ocean origin water into the deep WSG since 14.5 ± 0.2 ka.