Abrupt changes of intermediate-water oxygen in the northwestern Pacific during the last 27 kyr

Ishizaki, Yui; Ohkushi, Ken’ichi; Ito, Takashi; Kawahata, Hodaka

doi:10.1007/s00367-008-0128-0

Cited by 16 publications

(12 citation statements)

References 20 publications

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“…Nonetheless, the timing of the authigenic U decrease is very similar within multiple deep cores from the region (Figure 3) and is also broadly coincident with the first sharp rise of d 13 C at 3300 m ( Figure 2). This sequence of change was previously observed in North Pacific geochemical records from 3300 and 3610 m depth [Galbraith et al, 2007;Jaccard et al, 2009;Keigwin, 1998] Ikehara et al, 2006;Ishizaki et al, 2009;Jaccard and Galbraith, 2012;Shibahara et al, 2007]. We note that Gebhardt et al [2008] inferred deep water formation in the NE Pacific during HS1 based on their interpretation of the planktonic Δ 14 C record; however, this is inconsistent with the much higher-resolution planktonic-benthic data of Lund et al [2011].…”

Section: Resultssupporting

confidence: 43%

“…This sequence of change was previously observed in North Pacific geochemical records from 3300 and 3610 m depth [ Galbraith et al ., ; Jaccard et al ., ; Keigwin , ], and is supported by the new data, consistent with a poorly‐ventilated deep ocean throughout this time interval that extended to within 2400 m of the surface. In contrast, bottom water oxygen concentrations appear to have been relatively high during HS1 at <1400 m depths on both sides of the North Pacific, including the Bering Sea [ Addison et al ., ; Caissie et al ., ; Cook et al ., ; Crusius et al ., ; Ikehara et al ., ; Ishizaki et al ., ; Jaccard and Galbraith , ; Shibahara et al ., ]. We note that Gebhardt et al .…”

Section: Resultsmentioning

confidence: 99%

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Direct ventilation of the North Pacific did not reach the deep ocean during the last deglaciation

Jaccard

Galbraith

2013

Geophysical Research Letters

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Despite its tremendous size, the deep North Pacific has received relatively little attention by paleoceanographers. It was recently suggested that the deep North Pacific was directly ventilated by dense waters formed in the subarctic Pacific during Heinrich Stadial 1 (HS1) of the early deglaciation. Here we present new redox‐sensitive trace metal data from a sediment core at 2393 m in the subarctic Pacific, in comparison with previously published data from elsewhere in the region. The combined picture shows no sign of ventilation during the early deglaciation in any available core from water depths of 2393 m and deeper, while the deepest core to display clear signs of enhanced ventilation during HS1 was raised from 1366 m water depth. Thus, it appears likely that, although the North Pacific was well ventilated to intermediate depths during HS1, the deep ocean did not receive a significant input of dense waters from a local source, but remained isolated from the surface waters above.

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Section: Resultssupporting

confidence: 43%

Section: Resultsmentioning

confidence: 99%

Direct ventilation of the North Pacific did not reach the deep ocean during the last deglaciation

Jaccard

Galbraith

2013

Geophysical Research Letters

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“…The YD marked a hiatus in laminae deposition in 3JPC and 51JPC. This hiatus is attributed to an increase in oxygenation due to changes in North Pacific Intermediate Water ventilation (Kennett & Ingram, ; Max et al, ; Okazaki et al, ; Zheng et al, ), primary productivity (Crusius et al, ; Mix et al, ; Schlung et al, ), or a combination of both (Gorbarenko et al, ; Hendy & Pedersen, ; Ishizaki et al, ; Kim et al, ). The massive sediment character of the YD is marked by decreased productivity in all three Bering Sea cores with decreased sedimentation rate, TOC, N org , and depletion of δ 13 C org .…”

Section: Discussionmentioning

confidence: 99%

Oceanographic and Climatic Change in the Bering Sea, Last Glacial Maximum to Holocene

Pelto

Caissie

Petsch

et al. 2018

Paleoceanog and Paleoclimatol

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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.

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“…The increase in dissolved oxygen in O-LGM was considerable but agreed well with proxy reconstructions for the upper ocean. The oxygen-poor intermediate waters of the western North Pacific (Ishizaki et al, 2009;Shibahara et al, 2007), eastern North Pacific (Cannariato and Kennett, 1999;Cartapanis et al, 2011;Chang et al, 2014;Dean, 2007;Nameroff et al, 2004;Pride et al, 1999;Ohkushi et al, 2013;van Geen et al, 2003), eastern South Pacific (Martinez et al, 2006;Muratli et al, 2010;Salvatteci et al, 2016), equatorial Pacific (Leduc et al, 2010) and Indian Ocean (Reichart et al, 1998;Suthhof et al, 2001;van der Weijden et al, 2006) were better oxygenated at the LGM relative to the PI climate. An important consequence of oxygenating the upper ocean is a reduction in the strength of denitrification in these regions.…”

Section: Dissolved Oxygenmentioning

confidence: 95%

The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

et al. 2016

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Abstract. The ocean's ability to store large quantities of carbon, combined with the millennial longevity over which this reservoir is overturned, has implicated the ocean as a key driver of glacial-interglacial climates. However, the combination of processes that cause an accumulation of carbon within the ocean during glacial periods is still under debate. Here we present simulations of the Last Glacial Maximum (LGM) using the CSIRO Mk3L-COAL (Carbon-OceanAtmosphere-Land) earth system model to test the contribution of physical and biogeochemical processes to ocean carbon storage. For the LGM simulation, we find a significant global cooling of the surface ocean (3.2 • C) and the expansion of both minimum and maximum sea ice cover broadly consistent with proxy reconstructions. The glacial ocean stores an additional 267 Pg C in the deep ocean relative to the pre-industrial (PI) simulation due to stronger Antarctic Bottom Water formation. However, 889 Pg C is lost from the upper ocean via equilibration with a lower atmospheric CO 2 concentration and a global decrease in export production, causing a net loss of carbon relative to the PI ocean. The LGM deep ocean also experiences an oxygenation (> 100 mmol O 2 m −3 ) and deepening of the calcite saturation horizon (exceeds the ocean bottom) at odds with proxy reconstructions. With modifications to key biogeochemical processes, which include an increased export of organic matter due to a simulated release from iron limitation, a deepening of remineralisation and decreased inorganic carbon export driven by cooler temperatures, we find that the carbon content of the glacial ocean can be sufficiently increased (317 Pg C) to explain the reduction in atmospheric and terrestrial carbon at the LGM (194 ± 2 and 330 ± 400 Pg C, respectively). Assuming an LGM-PI difference of 95 ppm pCO 2 , we find that 55 ppm can be attributed to the biological pump, 28 ppm to circulation changes and the remaining 12 ppm to solubility. The biogeochemical modifications also improve model-proxy agreement in export production, carbonate chemistry and dissolved oxygen fields. Thus, we find strong evidence that variations in the oceanic biological pump exert a primary control on the climate.

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Abrupt changes of intermediate-water oxygen in the northwestern Pacific during the last 27 kyr

Cited by 16 publications

References 20 publications

Direct ventilation of the North Pacific did not reach the deep ocean during the last deglaciation

Direct ventilation of the North Pacific did not reach the deep ocean during the last deglaciation

Oceanographic and Climatic Change in the Bering Sea, Last Glacial Maximum to Holocene

The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

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