Sedimentary record of rapid climatic variability in the North Atlantic Ocean during the Last Glacial Cycle

Cortijo, Elsa; Yiou, Pascal; Labeyrie, Laurent D; Cremer, Michael C.

doi:10.1029/95pa02021

Cited by 62 publications

(25 citation statements)

References 43 publications

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“…Rapid climate change (Dansgaard^Oeschger (D^O) cycles) has been documented in Greenland ice cores (Johnsen et al, 1992;Chappellaz et al, 1993;Dansgaard et al, 1993) as well as in marine core records of the North Atlantic McManus et al, 1994;Cortijo et al, 1995;Adkins et al, 1997;Fronval and Jansen, 1997;Lototskaya and Ganssen, 1999). Alterations of the North Atlantic thermohaline circulation are thought to be responsible for these rapid climatic changes, and the synchronism between the North Atlantic and the Greenland ice-sheet records seems to support, at least partly, this hypothesis.…”

Section: Introductionmentioning

confidence: 76%

Radiolarian-based paleotemperatures during the last 160 kyr at ODP Site 1089 (Southern Ocean, Atlantic Sector)

Cortese

Abelmann

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

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Two cores, Site 1089 (ODP Leg 177) and PS2821-1, recovered from the same location (40 ‡56PS; 9 ‡54PE) at the Subtropical Front (STF) in the Atlantic Sector of the Southern Ocean, provide a high-resolution climatic record, with an average temporal resolution of less than 600 yr. A multi-proxy approach was used to produce an age model for Core PS2821-1, and to correlate the two cores. Both cores document the last climatic cycle, from Marine Isotopic Stage 6 (MIS 6, ca. 160 kyr BP, ka) to present. Summer sea-surface temperatures (SSSTs) have been estimated, with a standard error of ca. þ 1.16 ‡C, for the down core record by using Q-mode factor analysis (Imbrie and Kipp method). The paleotemperatures show a 7 ‡C warming at Termination II (last interglacial, transition from MIS 6 to MIS 5). This transition from glacial to interglacial paleotemperatures (with maximum temperatures ca. 3 ‡C warmer than present at the core location) occurs earlier than the corresponding shift in N 18 O values for benthic foraminifera from the same core; this suggests a lead of Southern Ocean paleotemperature changes compared to the global ice-volume changes, as indicated by the benthic isotopic record. The climatic evolution of the record continues with a progressive temperature deterioration towards MIS 2. High-frequency, millennial-scale climatic instability has been documented for MIS 3 and part of MIS 4, with sudden temperature variations of almost the same magnitude as those observed at the transitions between glacial and interglacial times. These changes occur during the same time interval as the Dansgaard^Oeschger cycles recognized in the N 18 O ice record of the GRIP and GISP ice cores from Greenland, and seem to be connected to rapid changes in the STF position in relation to the core location. Sudden cooling episodes ('Younger Dryas (YD)-type' and 'Antarctic Cold Reversal (ACR)-type' of events) have been recognized for both Termination I (ACR-I and YD-I events) and II (ACR-II and YD-II events), and imply that our core is located in an optimal position in order to record events triggered by phenomena occurring in both hemispheres. Spectral analysis of our SSST record displays strong analogies, particularly for high, sub-orbital frequencies, to equivalent records from Vostok (Antarctica) and from the Subtropical North Atlantic ocean. This implies that the climatic variability of widely separated areas (the Antarctic continent, the Subtropical North Atlantic, and the Subantarctic South Atlantic) can be strongly coupled and co-varying at millennial time scales (a few to 10-ka periods), and eventually induced by the same triggering mechanisms. Climatic variability has also been documented for supposedly warm and stable interglacial intervals (MIS 1 and 5), with several cold events which can be correlated to other Southern Ocean and North Atlantic sediment records. ß

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Section: Introductionmentioning

confidence: 76%

Radiolarian-based paleotemperatures during the last 160 kyr at ODP Site 1089 (Southern Ocean, Atlantic Sector)

Cortese

Abelmann

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…Based on a detailed and AMS-14 C-dated stratigraphy for the last glacial cycle, we particularly focus on the short-term, i.e. decadal to centennial, changes in monsoonal climate and trace their timing, phase relationship, and linkages in general to global climate changes such as Heinrich and=or Dansgaard-Oeschger (D-Oe) events defined in the North Atlantic realm (Bond et al, 1992(Bond et al, , 1997Cortijo et al, 1995) and the associated changes in the global thermohaline circulation (Broecker et al, 1988;Sarnthein et al, 1994b;Seidov et al, 1996). Similar teleconnections were recently found and=or postulated by Kennett and Ingram (1995) and Kotilainen and Shackleton (1995) by studying paleoclimatic sediment records from the eastern and northwestern Pacific margins.…”

Section: Introductionmentioning

confidence: 99%

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

et al. 1999

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Based on the study of 10 sediment cores and 40 core-top samples from the South China Sea (SCS) we obtained proxy records of past changes in East Asian monsoon climate on millennial to bidecadal time scales over the last 220,000 years. Climate proxies such as global sea level, estimates of paleotemperature, salinity, and nutrients in surface water, ventilation of deep water, paleowind strength, freshwater lids, fluvial and=or eolian sediment supply, and sediment winnowing on the sea floor were derived from planktonic and benthic stable-isotope records, the distribution of siliciclastic grain sizes, planktonic foraminifera species, and the U K 37 biomarker index. Four cores were AMS-14 C-dated. Two different regimes of monsoon circulation dominated the SCS over the last two glacial cycles, being linked to the minima and maxima of Northern Hemisphere solar insolation. (1) Glacial stages led to a stable estuarine circulation and a strong O 2 -minimum layer via a closure of the Borneo sea strait. Strong northeast monsoon and cool surface water occurred during winter, in part fed by an inflow from the north tip of Luzon. In contrast, summer temperatures were as high as during interglacials, hence the seasonality was strong. Low wetness in subtropical South China was opposed to large river input from the emerged Sunda shelf, serving as glacial refuge for tropical forest. (2) Interglacials were marked by a strong inflow of warm water via the Borneo sea strait, intense upwelling southeast of Vietnam and continental wetness in China during summer, weaker northeast monsoon and high sea-surface temperatures during winter, i.e. low seasonality. On top of the long-term variations we found millennial-to centennial-scale cold and dry, warm and humid spells during the Holocene, glacial Terminations I and II, and Stage 3. The spells were coeval with published variations in the Indian monsoon and probably, with the cold Heinrich and warm Dansgaard-Oeschger events recorded in Greenland ice cores, thus suggesting global climatic teleconnections. Holocene oscillations in the runoff from South China centered around periodicities of 775 years, ascribed to subharmonics of the 1500-year cycle in oceanic thermohaline circulation. 102=84-year cycles are tentatively assigned to the Gleissberg period of solar activity. Phase relationships among various monsoon proxies near the onset of Termination IA suggest that summer-monsoon rains and fluvial runoff from South China had already intensified right after the last glacial maximum (LGM) insolation minimum, coeval with the start of Antarctic ice melt Wang et al. / Marine Geology 156 (1999) prior to the δ 18 O signals of global sea-level rise. Vice versa, the strength of winter-monsoon winds decreased in short centennial steps only 3000-4000 years later, along with the melt of glacial ice sheets in the Northern Hemisphere.

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“…Ici, nous utilisons une échelle de gris étalonnée linéairement de 0 (noir) à 100 (blanc). Cette échelle de gris a été élaborée par Cortijo et al (1995) pour mettre en évidence la sédimentation biogénique carbonatée dans des carottes océaniques.…”

Section: Analyses Physiquesunclassified

Caractérisation des sédiments récents du Fjord du Saguenay (Québec) à partir de traceurs physiques, géochimiques, isotopiques et micropaléontologiques

St‐Onge¹,

Leduc²,

Bilodeau³

et al. 2002

gpq

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Résumé Des analyses physiques (susceptibilité magnétique, densité, porosité et couleur), géochimiques (C org. , C inorg. , N), isotopiques ( 13 C et 15 N de la matière organique) et micropaléontologiques (foraminifères, diatomées, kystes de dinoflagellés, pollen, spores etc.) ont été réalisées dans les sédiments d'une carotte de ~2 m prélevée dans le bassin supérieur du fjord du Saguenay. La séquence étudiée représente environ 330 ans de sédimentation. Deux unités sédimentaires peuvent y être définies. Elles indiquent des changements majeurs dans la dynamique sédimentaire. La base de la séquence (endessous de ~70 cm) renferme des apports terrigènes dominants dont témoignent de faibles teneurs en 13 C et 15N de la matière organique, des rapports C/N élevés, la présence de carbonates détritiques et une faible concentration de microfossiles marins. Cette unité aurait été mise en place à la suite du tremblement de terre de 1663. La deuxième unité (~70-0 cm) présente de fortes teneurs en C org. , des apports biogéniques marins notables et évoque une sédimentation de type hémipélagique. Les assemblages diversifiés de dinokystes et les concentrations élevées de diatomées y témoignent d'une productivité planctonique autotrophe et hétérotrophe. L'abondance des réseaux organiques de foraminifères révèle une productivité benthique considérable, mais la rareté de leurs tests indique une dissolution du carbonate de calcium. Enfin, les profils polliniques illustrent, au sommet de la séquence (30-0 cm), l'augmentation des apports rudéraux en relation avec le déboisement récent.

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Sedimentary record of rapid climatic variability in the North Atlantic Ocean during the Last Glacial Cycle

Cited by 62 publications

References 43 publications

Radiolarian-based paleotemperatures during the last 160 kyr at ODP Site 1089 (Southern Ocean, Atlantic Sector)

Radiolarian-based paleotemperatures during the last 160 kyr at ODP Site 1089 (Southern Ocean, Atlantic Sector)

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

Caractérisation des sédiments récents du Fjord du Saguenay (Québec) à partir de traceurs physiques, géochimiques, isotopiques et micropaléontologiques

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