Link between the North and South Atlantic during the Heinrich events of the last glacial period

Vidal, Laurent; Schneider, Ralph R; Marchal, Olivier; Bickert, T.; Stocker, Thomas F.; Wefer, Gerold

doi:10.1007/s003820050321

Cited by 118 publications

(53 citation statements)

References 55 publications

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“…This is greater than the frequently cited −125 m (e.g., 24, 80) that is usually based on observations uncorrected for isostatic effects. Heinrich event H2 at ∼19.5-22 14 C ka (∼25 ka BP) (77,81,82) is not associated with a recognizable sea-level signal. iii) Onset of deglaciation at ∼21-20 ka BP with a short-lived global sea-level rise of ∼10-15 m before 18 ka.…”

Section: Discussionmentioning

confidence: 99%

Sea level and global ice volumes from the Last Glacial Maximum to the Holocene

Lambeck

Rouby

Purcell

et al. 2014

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

1,924

1,613

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The major cause of sea-level change during ice ages is the exchange of water between ice and ocean and the planet's dynamic response to the changing surface load. Inversion of ∼1,000 observations for the past 35,000 y from localities far from former ice margins has provided new constraints on the fluctuation of ice volume in this interval. Key results are: (i) a rapid final fall in global sea level of ∼40 m in <2,000 y at the onset of the glacial maximum ∼30,000 y before present (30 ka BP); (ii) a slow fall to −134 m from 29 to 21 ka BP with a maximum grounded ice volume of ∼52 × 10 6 km 3 greater than today; (iii) after an initial short duration rapid rise and a short interval of near-constant sea level, the main phase of deglaciation occurred from ∼16.5 ka BP to ∼8.2 ka BP at an average rate of rise of 12 m·ka −1 punctuated by periods of greater, particularly at 14.5-14.0 ka BP at ≥40 mm·y −1 (MWP-1A), and lesser, from 12.5 to 11.5 ka BP (Younger Dryas), rates; (iv) no evidence for a global MWP-1B event at ∼11.3 ka BP; and (v) a progressive decrease in the rate of rise from 8.2 ka to ∼2.5 ka BP, after which ocean volumes remained nearly constant until the renewed sea-level rise at 100-150 y ago, with no evidence of oscillations exceeding ∼15-20 cm in time intervals ≥200 y from 6 to 0.15 ka BP.he understanding of the change in ocean volume during glacial cycles is pertinent to several areas of earth science: for estimating the volume of ice and its geographic distribution through time (1); for calibrating isotopic proxy indicators of ocean volume change (2, 3); for estimating vertical rates of land movement from geological data (4); for examining the response of reef development to changing sea level (5); and for reconstructing paleo topographies to test models of human and other migrations (6). Estimates of variations in global sea level come from direct observational evidence of past sea levels relative to present and less directly from temporal variations in the oxygen isotopic signal of ocean sediments (7). Both yield modeldependent estimates. The first requires assumptions about processes that govern how past sea levels are recorded in the coastal geology or geomorphology as well as about the tectonic, isostatic, and oceanographic contributions to sea level change. The second requires assumptions about the source of the isotopic or chemical signatures of marine sediments and about the relative importance of growth or decay of the ice sheets, of changes in ocean and atmospheric temperatures, or from local or regional factors that control the extent and time scales of mixing within ocean basins.Both approaches are important and complementary. The direct observational evidence is restricted to time intervals or climatic and tectonic settings that favor preservation of the records through otherwise successive overprinting events. As a result, the records become increasingly fragmentary backward in time. The isotopic evidence, in contrast, being recorded in deep-water carbonate marine sediments, extends further...

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Section: Discussionmentioning

confidence: 99%

Sea level and global ice volumes from the Last Glacial Maximum to the Holocene

Lambeck

Rouby

Purcell

et al. 2014

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

1,924

1,613

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“…In fact, the role of the ocean and atmosphere as transmission agents is highly debated (e.g. Vidal et al 1999). It is pre-empted that climate signals seem to reach the northern Benguela both through the ocean, i.e.…”

Section: The Global Propagation Of Climate Signalsmentioning

confidence: 99%

“…Kim et al (2002) and Vidal et al (1999) report rising temperatures during 'Heinrich Event 1', a period when the North Atlantic experienced prominent cooling ($15000 BP). This inter-hemispheric asynchrony is attributed to decreased (or increased) heat transport from the South into the North Atlantic when the conveyor slows down (or accelerates) (Stuiver et al 1995;Rçhle-mann et al 1999;Kim et al 2002).…”

Section: Pathway Oceanmentioning

confidence: 99%

Nutrient regime and upwelling in the northern Benguela since the middle Holocene in a global context - a multi-proxy approach

et al. 2011

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The last 5500 years of climate change and environmental response in the northern Benguela Coastal Upwelling are reconstructed by means of three sediment cores from the inner shelf off central Namibia. The study is based on nutrient (delta(15)N, delta(13)C) and productivity proxies (accumulation rates of total organic carbon; AR(TOC)). Reconstructed sea surface temperatures (alkenone-derived SST) and temperatures at subsurface depths (T(delta 18O); based on tests of planktonic foraminifers) reflect the physical boundary conditions. The selection of proxy indicators proved a valuable basis for robust palaeo-climatic reconstructions, with the resolution ranging from multi-decadal (NAM1) over centennial (core 178) to millennial scale (core 226620). The northern Benguela experienced pronounced and rapid perturbation during the middle and late Holocene, and apparently, not all are purely local in character. In fact, numerous correlations with records from the adjacent South African subcontinent and the northern hemisphere testify to global climatic teleconnections. The Holocene Hypsithermal, for instance, is just as evident as the Little Ice Age (LIA) and the Roman Warm Period. The marked SST-rise associated with the latter is substantiated by other marine and terrestrial data from the South African realm. The LIA (at least its early stages) manifests itself in intensified winds and upwelling, which accords with increased rainfall receipts above the continental interior. It appears that climate signals are transferred both via the atmosphere and ocean. The combined analysis of SST and T(delta 18O) proved a useful tool in order to differentiate between both pathways. SSTs are primarily controlled by the intensity of atmospheric circulation features, reflecting changes of upwelling-favourable winds. T(delta 18O) records the temperature of the source water and often correlates with global ocean conveyor speed due to varying inputs of warm Agulhas Water. It seems as though conveyor slowdown or acceleration not only affected the temperature of the source water but also its nutrient content. This relationship between source water quality and conveyor speed is already known from glacial times

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“…While the formation of NADW is related to northern hemispheric insolation and ice-sheet dynamics (Broecker and Denton, 1989;Berger and Wefer, 1996), the intensities of the Agulhas Current and the ACC depend on temperatures and the con¢g-urations of the major wind ¢elds in the southern hemisphere (Shannon et al, 1990;Klinck and Smith, 1993). Latest reconstructions from icecore data and marine proxy records from the southern hemisphere indicate changes in atmospheric CO 2 and variations in air and sea-surface temperatures to have preceded changes in global ice volume on short and long time scales (Charles et al, 1996;Little et al, 1997;Blunier et al, 1998;Brathauer and Abelmann, 1999;Vidal et al, 1999). This phase lead on the Milankovitch time scale is not evident from our data, which suggest a more or less synchronous response of regional conveyor circulation to global ice-volume changes, as also inferred from other sediment records in the southeastern South Atlantic by means of clay mineralogy (Diekmann et al, 1996(Diekmann et al, , 1999.…”

Section: Regional Conveyor Circulation In Response To Climate Variabimentioning

confidence: 99%

Late Quaternary variability of ocean circulation in the southeastern South Atlantic inferred from the terrigenous sediment record of a drift deposit in the southern Cape Basin (ODP Site 1089)

Kuhn

Diekmann

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

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During Leg 177 of the Ocean Drilling Program, an expanded sequence of Pliocene to Holocene calcareous muds was recovered at Site 1089 on a drift deposit in the southern Cape Basin (SE South Atlantic). The reconstruction of detrital sources and modes of sediment transport gives insight into the operational modes of regional current systems in response to climate variability over the last 590 kyr, as inferred from sedimentological and mineralogical parameters of the terrigenous sediment fraction. Terrigenous sediments mainly originate from African sources with minor contributions from distant southern sources (South America and Antarctica) and are supplied by circumpolar water masses, North Atlantic Deep Water (NADW), and surface currents of the Agulhas Current. Changes in clay mineralogy as tracers of deep and shallow ocean circulation, best displayed by variations in quartz/feldspar ratios and kaolinite/chlorite ratios of clay, reflect both the northward displacement of NADW injection into the Antarctic Circumpolar Current and a weakening of Agulhas Current leakage from the Indian Ocean around South Africa to the South Atlantic during glacial stages, sub-stages, and stadials. Modifications of these regional current patterns are consistent with perturbations in global conveyor circulation and climate variability on Milankovitch and subMilankovitch time scales. Elevated mass-accumulation rates of terrigenous matter generally document high particle fluxes and focusing effects by bottom-current action throughout the late Quaternary. Current sorting and coarsening of terrigenous mud, independently of its source signals, prevails during interglacial periods and is linked to a stronger flow of Antarctic Bottom Water and the invigoration of deep contour currents in response to long-term changes (100-kyr cyclicity) in Antarctic ice-sheet dynamics, high-amplitude fluctuations in global sea level, and increased bottomwater formation. ß

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Link between the North and South Atlantic during the Heinrich events of the last glacial period

Cited by 118 publications

References 55 publications

Sea level and global ice volumes from the Last Glacial Maximum to the Holocene

Sea level and global ice volumes from the Last Glacial Maximum to the Holocene

Nutrient regime and upwelling in the northern Benguela since the middle Holocene in a global context - a multi-proxy approach

Late Quaternary variability of ocean circulation in the southeastern South Atlantic inferred from the terrigenous sediment record of a drift deposit in the southern Cape Basin (ODP Site 1089)

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