A review of the Australian-New Zealand sector of the Southern Ocean over the last 30ka (Aus-INTIMATE project)

H. C. Bostock, T Barrows, L Carter, Z Chase, G Cortese, G. B. Dunbar, Michael Ellwood, B Hayward, W Howard, H. L. Neil, T. L. Noble, Andrew Mackintosh, P. T. Moss, A. D. Moy, D. White, M. J M Williams, L. K. Armand

    Research output: Contribution to journalArticle

    49 Citations (Scopus)

    Abstract

    The Australia/New Zealand region of the Southern Ocean is influenced by several of the major global water masses of the oceans and is the prime entry point for cold deep waters into the Pacific basin. During the last glacial there was increased sea-ice extent around Antarctica (as far north as 55°S), as well as increased iceberg presence inferred from ice-rafted debris. Evidence from microfossil assemblages suggests that sea surface temperatures (SST) were up to 7°C cooler, consistent with recent estimates of cooling for New Zealand derived from glacier modelling and other terrestrial proxies. The Subtropical Front (STF), Subantarctic Front (SAF) and Polar Front (PF) had migrated north, except where the position of the fronts were controlled bathymetrically. Despite the potential for iron fertilisation by increased dust input into the ocean during the glacial, there is limited evidence for higher total biological productivity in the Pacific sector of the Southern Ocean. The altered oceanic circulation during the glacial also decreased nutrients in the surface waters and affected the outgassing of CO2. This contributed to an increased storage of CO2 in the deep waters and lowering of the carbonate lysocline.During the deglaciation, sea-ice retreat and SST increased rapidly at ~18ka, roughly synchronous with the reinvigoration of deep water circulation in the Southern Ocean and the release of CO2 stored in the deep waters. The gradient in carbon isotopes (δ13Cbenthic) between Antarctic Intermediate Water (AAIW) and lower Circumpolar Deep Water (LCDW) was greatest at the start of the deglaciation, suggesting that the AAIW ventilation preceded LCDW ventilation, or there was a significant change in air-sea fractionation of δ13C. There was a slight enrichment in δ18Oplanktic, decrease in SSTs and a reduction in intermediate and deep water circulation between ~14 and 12.5kaBP during the Antarctic Cold Reversal (ACR), coincident with glacier advances in the New Zealand Southern Alps and other terrestrial records of cooling. Following the ACR, there was a second, more minor, release of deep water CO2, most likely related to reinvigoration of North Atlantic Deep Water (NADW). From 10ka onwards the modern intermediate and deep water circulation was established.Air temperatures and SSTs reached a maximum in the early Holocene, with the STF located at its most southerly position, and there was a widespread retreat of Antarctic ice sheets to their modern position. Adecline to modern SST and air temperatures in the mid to late Holocene followed. While millennial cycles overprinted on the SST and δ18Oplanktic records, may be the result of subtle changes in the position and strength of the westerly winds during the Holocene.

    Original languageEnglish
    Pages (from-to)35-57
    Number of pages23
    JournalQuaternary Science Reviews
    Volume74
    DOIs
    Publication statusPublished - 5 Aug 2013

    Fingerprint

    New Zealand
    deep water
    oceans
    water
    sea surface temperature
    ocean
    surface temperature
    ice
    carbon dioxide
    water flow
    Antarctic Intermediate Water
    glaciers
    intermediate water
    Holocene
    deglaciation
    air temperature
    cooling
    sea ice
    deep water ventilation
    icebergs

    Cite this

    Bostock, H. C. ; Barrows, T ; Carter, L ; Chase, Z ; Cortese, G ; Dunbar, G. B. ; Ellwood, Michael ; Hayward, B ; Howard, W ; Neil, H. L. ; Noble, T. L. ; Mackintosh, Andrew ; Moss, P. T. ; Moy, A. D. ; White, D. ; Williams, M. J M ; Armand, L. K. / A review of the Australian-New Zealand sector of the Southern Ocean over the last 30ka (Aus-INTIMATE project). In: Quaternary Science Reviews. 2013 ; Vol. 74. pp. 35-57.
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    abstract = "The Australia/New Zealand region of the Southern Ocean is influenced by several of the major global water masses of the oceans and is the prime entry point for cold deep waters into the Pacific basin. During the last glacial there was increased sea-ice extent around Antarctica (as far north as 55°S), as well as increased iceberg presence inferred from ice-rafted debris. Evidence from microfossil assemblages suggests that sea surface temperatures (SST) were up to 7°C cooler, consistent with recent estimates of cooling for New Zealand derived from glacier modelling and other terrestrial proxies. The Subtropical Front (STF), Subantarctic Front (SAF) and Polar Front (PF) had migrated north, except where the position of the fronts were controlled bathymetrically. Despite the potential for iron fertilisation by increased dust input into the ocean during the glacial, there is limited evidence for higher total biological productivity in the Pacific sector of the Southern Ocean. The altered oceanic circulation during the glacial also decreased nutrients in the surface waters and affected the outgassing of CO2. This contributed to an increased storage of CO2 in the deep waters and lowering of the carbonate lysocline.During the deglaciation, sea-ice retreat and SST increased rapidly at ~18ka, roughly synchronous with the reinvigoration of deep water circulation in the Southern Ocean and the release of CO2 stored in the deep waters. The gradient in carbon isotopes (δ13Cbenthic) between Antarctic Intermediate Water (AAIW) and lower Circumpolar Deep Water (LCDW) was greatest at the start of the deglaciation, suggesting that the AAIW ventilation preceded LCDW ventilation, or there was a significant change in air-sea fractionation of δ13C. There was a slight enrichment in δ18Oplanktic, decrease in SSTs and a reduction in intermediate and deep water circulation between ~14 and 12.5kaBP during the Antarctic Cold Reversal (ACR), coincident with glacier advances in the New Zealand Southern Alps and other terrestrial records of cooling. Following the ACR, there was a second, more minor, release of deep water CO2, most likely related to reinvigoration of North Atlantic Deep Water (NADW). From 10ka onwards the modern intermediate and deep water circulation was established.Air temperatures and SSTs reached a maximum in the early Holocene, with the STF located at its most southerly position, and there was a widespread retreat of Antarctic ice sheets to their modern position. Adecline to modern SST and air temperatures in the mid to late Holocene followed. While millennial cycles overprinted on the SST and δ18Oplanktic records, may be the result of subtle changes in the position and strength of the westerly winds during the Holocene.",
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    author = "Bostock, {H. C.} and T Barrows and L Carter and Z Chase and G Cortese and Dunbar, {G. B.} and Michael Ellwood and B Hayward and W Howard and Neil, {H. L.} and Noble, {T. L.} and Andrew Mackintosh and Moss, {P. T.} and Moy, {A. D.} and D. White and Williams, {M. J M} and Armand, {L. K.}",
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    Bostock, HC, Barrows, T, Carter, L, Chase, Z, Cortese, G, Dunbar, GB, Ellwood, M, Hayward, B, Howard, W, Neil, HL, Noble, TL, Mackintosh, A, Moss, PT, Moy, AD, White, D, Williams, MJM & Armand, LK 2013, 'A review of the Australian-New Zealand sector of the Southern Ocean over the last 30ka (Aus-INTIMATE project)', Quaternary Science Reviews, vol. 74, pp. 35-57. https://doi.org/10.1016/j.quascirev.2012.07.018

    A review of the Australian-New Zealand sector of the Southern Ocean over the last 30ka (Aus-INTIMATE project). / Bostock, H. C.; Barrows, T; Carter, L; Chase, Z; Cortese, G; Dunbar, G. B.; Ellwood, Michael; Hayward, B; Howard, W; Neil, H. L.; Noble, T. L.; Mackintosh, Andrew; Moss, P. T.; Moy, A. D.; White, D.; Williams, M. J M; Armand, L. K.

    In: Quaternary Science Reviews, Vol. 74, 05.08.2013, p. 35-57.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - A review of the Australian-New Zealand sector of the Southern Ocean over the last 30ka (Aus-INTIMATE project)

    AU - Bostock, H. C.

    AU - Barrows, T

    AU - Carter, L

    AU - Chase, Z

    AU - Cortese, G

    AU - Dunbar, G. B.

    AU - Ellwood, Michael

    AU - Hayward, B

    AU - Howard, W

    AU - Neil, H. L.

    AU - Noble, T. L.

    AU - Mackintosh, Andrew

    AU - Moss, P. T.

    AU - Moy, A. D.

    AU - White, D.

    AU - Williams, M. J M

    AU - Armand, L. K.

    PY - 2013/8/5

    Y1 - 2013/8/5

    N2 - The Australia/New Zealand region of the Southern Ocean is influenced by several of the major global water masses of the oceans and is the prime entry point for cold deep waters into the Pacific basin. During the last glacial there was increased sea-ice extent around Antarctica (as far north as 55°S), as well as increased iceberg presence inferred from ice-rafted debris. Evidence from microfossil assemblages suggests that sea surface temperatures (SST) were up to 7°C cooler, consistent with recent estimates of cooling for New Zealand derived from glacier modelling and other terrestrial proxies. The Subtropical Front (STF), Subantarctic Front (SAF) and Polar Front (PF) had migrated north, except where the position of the fronts were controlled bathymetrically. Despite the potential for iron fertilisation by increased dust input into the ocean during the glacial, there is limited evidence for higher total biological productivity in the Pacific sector of the Southern Ocean. The altered oceanic circulation during the glacial also decreased nutrients in the surface waters and affected the outgassing of CO2. This contributed to an increased storage of CO2 in the deep waters and lowering of the carbonate lysocline.During the deglaciation, sea-ice retreat and SST increased rapidly at ~18ka, roughly synchronous with the reinvigoration of deep water circulation in the Southern Ocean and the release of CO2 stored in the deep waters. The gradient in carbon isotopes (δ13Cbenthic) between Antarctic Intermediate Water (AAIW) and lower Circumpolar Deep Water (LCDW) was greatest at the start of the deglaciation, suggesting that the AAIW ventilation preceded LCDW ventilation, or there was a significant change in air-sea fractionation of δ13C. There was a slight enrichment in δ18Oplanktic, decrease in SSTs and a reduction in intermediate and deep water circulation between ~14 and 12.5kaBP during the Antarctic Cold Reversal (ACR), coincident with glacier advances in the New Zealand Southern Alps and other terrestrial records of cooling. Following the ACR, there was a second, more minor, release of deep water CO2, most likely related to reinvigoration of North Atlantic Deep Water (NADW). From 10ka onwards the modern intermediate and deep water circulation was established.Air temperatures and SSTs reached a maximum in the early Holocene, with the STF located at its most southerly position, and there was a widespread retreat of Antarctic ice sheets to their modern position. Adecline to modern SST and air temperatures in the mid to late Holocene followed. While millennial cycles overprinted on the SST and δ18Oplanktic records, may be the result of subtle changes in the position and strength of the westerly winds during the Holocene.

    AB - The Australia/New Zealand region of the Southern Ocean is influenced by several of the major global water masses of the oceans and is the prime entry point for cold deep waters into the Pacific basin. During the last glacial there was increased sea-ice extent around Antarctica (as far north as 55°S), as well as increased iceberg presence inferred from ice-rafted debris. Evidence from microfossil assemblages suggests that sea surface temperatures (SST) were up to 7°C cooler, consistent with recent estimates of cooling for New Zealand derived from glacier modelling and other terrestrial proxies. The Subtropical Front (STF), Subantarctic Front (SAF) and Polar Front (PF) had migrated north, except where the position of the fronts were controlled bathymetrically. Despite the potential for iron fertilisation by increased dust input into the ocean during the glacial, there is limited evidence for higher total biological productivity in the Pacific sector of the Southern Ocean. The altered oceanic circulation during the glacial also decreased nutrients in the surface waters and affected the outgassing of CO2. This contributed to an increased storage of CO2 in the deep waters and lowering of the carbonate lysocline.During the deglaciation, sea-ice retreat and SST increased rapidly at ~18ka, roughly synchronous with the reinvigoration of deep water circulation in the Southern Ocean and the release of CO2 stored in the deep waters. The gradient in carbon isotopes (δ13Cbenthic) between Antarctic Intermediate Water (AAIW) and lower Circumpolar Deep Water (LCDW) was greatest at the start of the deglaciation, suggesting that the AAIW ventilation preceded LCDW ventilation, or there was a significant change in air-sea fractionation of δ13C. There was a slight enrichment in δ18Oplanktic, decrease in SSTs and a reduction in intermediate and deep water circulation between ~14 and 12.5kaBP during the Antarctic Cold Reversal (ACR), coincident with glacier advances in the New Zealand Southern Alps and other terrestrial records of cooling. Following the ACR, there was a second, more minor, release of deep water CO2, most likely related to reinvigoration of North Atlantic Deep Water (NADW). From 10ka onwards the modern intermediate and deep water circulation was established.Air temperatures and SSTs reached a maximum in the early Holocene, with the STF located at its most southerly position, and there was a widespread retreat of Antarctic ice sheets to their modern position. Adecline to modern SST and air temperatures in the mid to late Holocene followed. While millennial cycles overprinted on the SST and δ18Oplanktic records, may be the result of subtle changes in the position and strength of the westerly winds during the Holocene.

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    KW - Alkenones

    KW - Antarctic Circumpolar Current

    KW - Antarctic Cold Reversal

    KW - Antarctic ice-sheets

    KW - Australia

    KW - Diatoms

    KW - Dust

    KW - Foraminifera

    KW - Glaciers

    KW - Holocene

    KW - INTIMATE

    KW - LCDW

    KW - LGM

    KW - Mg/Ca

    KW - Moraines

    KW - New Zealand

    KW - Opal

    KW - Pacific

    KW - PF

    KW - Pollen

    KW - SAF

    KW - Sea-ice

    KW - Southern Ocean

    KW - SST

    KW - STF

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    U2 - 10.1016/j.quascirev.2012.07.018

    DO - 10.1016/j.quascirev.2012.07.018

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    EP - 57

    JO - Quaternary Science Reviews

    JF - Quaternary Science Reviews

    SN - 0277-3791

    ER -