Threshold behavior of millennial scale variability in deep water hydrography inferred from a 1.1 Ma long record of sediment provenance at the southern Gardar Drift

Grützner, Jens; Higgins, Sean M.

doi:10.1029/2009pa001873

Cited by 49 publications

(50 citation statements)

References 94 publications

(165 reference statements)

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“…Earlier studies speculated that the BS may have played a major role in the occurrence of these abrupt climate transitions through controlling the AMOC's response to external freshwater forcing (18)(19)(20)(21). Furthermore, in subsequent modeling studies it was demonstrated that a BS closure is likely to have affected the stability of the major Laurentide ice-sheet (24), consistent with a recent marine core study (25). With such a slow rate change, a freshwater forcing increment/ decrement of 0.1 Sv takes place over 500 y, thus maintaining the AMOC at a quasiequilibrium state throughout our simulation.…”

supporting

confidence: 49%

Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability

Meehl

Han

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80–11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the ocean conveyor belt circulation to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open.

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supporting

confidence: 49%

Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability

Meehl

Han

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…The K/Ti XRF intensity ratio reflects changing provenance of the terrigenous fraction, with an enhanced ice-rafted continental crust (high K) contribution during stadials vs. relatively more bottom current derived basaltic input (high Ti) during interstadials (cf. Ballini et al, 2006;Richter et al, 2006;Grützner and Higgins, 2010). Considerable short-term variability is superimposed upon the general stadial-interstadial pattern.…”

Section: Multiproxy Compilationmentioning

confidence: 99%

An ocean–ice coupled response during the last glacial: a view from a marine isotopic stage 3 record south of the Faeroe Shetland Gateway

et al. 2012

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Abstract. The rapid climatic variability characterising the Marine Isotopic Stage (MIS) 3 (∼ 60-30 cal ka BP) provides key issues to understand the atmosphere-ocean-cryosphere dynamics. Here we investigate the response of sea-surface paleoenvironments to the MIS3 climatic variability through the study of a high resolution oceanic sedimentological archive (core MD99-2281, 60 • 21 N; 09 • 27 W; 1197 m water depth), retrieved during the MD114-IMAGES (International Marine Global Change Study) cruise from the southern part of the Faeroe Bank. This sector was under the proximal influence of European ice sheets (Fennoscandian Ice Sheet to the East, British Irish Ice Sheet to the South) during the last glacial and thus probably responded to the MIS3 pulsed climatic changes.We conducted a multi-proxy analysis of core MD99-2281, including magnetic properties, x-ray fluorescence measurements, characterisation of the coarse (> 150 µm) lithic fraction (grain concentration) and the analysis of selected biogenic proxies (assemblages and stable isotope ratio of calcareous planktonic foraminifera, dinoflagellate cyst -e.g. dinocyst -assemblages). Results presented here are focussed on the dinocyst response, this proxy providing the reconstruction of past sea-surface hydrological conditions, qualitatively as well as quantitatively (e.g. transfer function sensu lato). Our study documents a very coherent and sensitive oceanic response to the MIS3 rapid climatic variability: strong fluctuations, matching those of stadial/interstadial climatic oscillations as depicted by Greenland ice cores, are recorded in the MD99-2281 archive. Proxies of terrigeneous and detritical material suggest increases in continental advection during Greenland Stadials (including Heinrich events), the latter corresponding also to southward migrations of polar waters. At the opposite, milder sea-surface conditions seem to develop during Greenland Interstadials. After 30 ka, reconstructed paleohydrological conditions evidence strong shifts in SST: this increasing variability seems consistent with the hypothesised coalescence of the British and Fennoscandian ice sheets at that time, which could have directly influenced sea-surface environments in the vicinity of core MD99-2281.

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“…Aiming at correcting for porosity changes and unevenness in the sediment surface, and for water condensation under the scanning foil, total counts for each element were normalized by the total counts for all elements at each depth interval following Bahr et al (). We used elemental log‐ratios to define diagenetic processes as well as enrichments and depletions of mobile elements against detrital input, following Weltje and Tjallingii () and Grützner and Higgins (). Colour records expressed in CIE‐L*a*b* colour space were obtained through image acquisition with the colour line‐scan camera integrated in the core scanner allowing (70 μm resolution).…”

Section: Methods and Method‐specific Resultsmentioning

confidence: 99%

Amplified environmental change: Evidence from land‐use and climate change in medieval Minorca

et al. 2018

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The debate on human environmental impact has often been locked into cause–effect reasoning, aiming at factoring human impact on top of climatic variability. Here we use evidence from Minorca and the Mediterranean region to show the potential for amplified environmental change emerging from complex feedbacks between climatic and historical events. Alluvial sediments collected in a gully reveal a 14‐ to 27‐fold increase in sediment accumulation rates, leading to the rapid aggradation of the valley floor from approximately ad 1300 onwards. These environmental changes coincided with the Feudal conquest of Minorca (ad 1287) and with the climatic shift from the Medieval Climate Anomaly (MCA, c. ad 900–1300) to the Little Ice Age (LIA, c. ad 1300–1850). This evidence of unprecedented sediment mobilisation, in context with climatic and historical events marking the Mediterranean region, highlights the implications for environmental vulnerability emerging from positive feedbacks between climate and land‐use. Understanding such interactions in historical contexts is paramount to increase our capacity for anticipatory learning in the face of rapid climatic, economical, and ecological transformations today.

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Threshold behavior of millennial scale variability in deep water hydrography inferred from a 1.1 Ma long record of sediment provenance at the southern Gardar Drift

Cited by 49 publications

References 94 publications

Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability

Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability

An ocean–ice coupled response during the last glacial: a view from a marine isotopic stage 3 record south of the Faeroe Shetland Gateway

Amplified environmental change: Evidence from land‐use and climate change in medieval Minorca

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