Fluctuations of vegetation and climate over the last 75 000 years in the Savanna Biome, South Africa: Tswaing Crater and Wonderkrater pollen sequences reviewed

Scott, Louis

doi:10.1016/j.quascirev.2016.05.035

Cited by 40 publications

(23 citation statements)

References 59 publications

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“…On the basis of palaeotemperature indices for this sequence, a cooling episode can be identified from at least one sample. 3,4 The calibrated date of circa 12 200 BP for this sample from Borehole 4 is almost identical to the mean date (12 433 cal BP) for the three Younger Dryas samples from Borehole 3.…”

Section: The Younger Dryas In Boreholesupporting

confidence: 52%

“…Critical in this regard are dates for the relevant deposits. Scott et al 3 and Scott 4 have used various techniques to resolve chronological issues. Whereas there is a linear relationship between age and depth for the last 16 000 years BP, the rate of deposition is not constant for earlier deposits for which the rate is slower and variable; hence the need for complex chronological modelling which presented a major challenge.…”

Section: Age-depth Relationshipsmentioning

confidence: 99%

“…Whereas there is a linear relationship between age and depth for the last 16 000 years BP, the rate of deposition is not constant for earlier deposits for which the rate is slower and variable; hence the need for complex chronological modelling which presented a major challenge. 3,4 However, for purposes of this study, attention is focused on age-depth relationships for the Terminal Pleistocene and Holocene, within the last 16 000 years, for periods in which least squares linear regression is suitable. This offers a relatively simple but robust approach for dating postglacial deposits at Wonderkrater.…”

Section: Age-depth Relationshipsmentioning

confidence: 99%

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temperature index in a Late Quaternary sequence at Wonderkrater, South Africa

Thackeray¹

2018

S. Afr. J. Sci.

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Section: The Younger Dryas In Boreholesupporting

confidence: 52%

Section: Age-depth Relationshipsmentioning

confidence: 99%

Section: Age-depth Relationshipsmentioning

confidence: 99%

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temperature index in a Late Quaternary sequence at Wonderkrater, South Africa

Thackeray¹

2018

S. Afr. J. Sci.

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“…Proxy data show spatial complexity (e.g. Baker et al, 2016;Chase et al, 2017;Chase, 2015, 2016;Dupont et al, 2011;Schefuß et al, 2011;Scott et al, 2012;Scott, 2016;Schmidt et al, 2014;Simon et al, 2015), and modelled LGM (26.5-19 ka;Clark et al, 2009) precipitation patterns for the region are highly variable and often do not even agree on the sign of precipitation change. For example, the PMIP3 model ensemble mean suggests increased LGM precipitation in the east of South Africa, with dry conditions towards the north (compared to the present day; Braconnot et al, 2007;.…”

Section: Introductionmentioning

confidence: 99%

Late Quaternary climate variability at Mfabeni peatland, eastern South Africa

et al. 2019

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Abstract. The scarcity of continuous, terrestrial, palaeoenvironmental records in eastern South Africa leaves the evolution of late Quaternary climate and its driving mechanisms uncertain. Here we use a ∼7 m long core from Mfabeni peatland (KwaZulu-Natal, South Africa) to reconstruct climate variability for the last 32 000 years (cal ka BP). We infer past vegetation and hydrological variability using stable carbon (δ13Cwax) and hydrogen isotopes (δDwax) of plant-wax n-alkanes and use Paq to reconstruct water table changes. Our results indicate that late Quaternary climate in eastern South Africa did not respond directly to orbital forcing or to changes in sea-surface temperatures (SSTs) in the western Indian Ocean. We attribute the arid conditions evidenced at Mfabeni during the Last Glacial Maximum (LGM) to low SSTs and an equatorward displacement of (i) the Southern Hemisphere westerlies, (ii) the subtropical high-pressure cell, and (iii) the South Indian Ocean Convergence Zone (SIOCZ), which we infer was linked to increased Antarctic sea-ice extent. The northerly location of the high-pressure cell and the SIOCZ inhibited moisture advection inland and pushed the rain-bearing cloud band north of Mfabeni, respectively. The increased humidity at Mfabeni between 19 and 14 cal kyr BP likely resulted from a southward retreat of the westerlies, the high-pressure cell, and the SIOCZ, consistent with a decrease in Antarctic sea-ice extent. Between 14 and 5 cal kyr BP, when the westerlies, the high-pressure cell, and the SIOCZ were in their southernmost position, local insolation became the dominant control, leading to stronger atmospheric convection and an enhanced tropical easterly monsoon. Generally drier conditions persisted during the past ca. 5 cal ka BP, probably resulting from an equatorward return of the westerlies, the high-pressure cell, and the SIOCZ. Higher SSTs and heightened El Niño–Southern Oscillation (ENSO) activity may have played a role in enhancing climatic variability during the past ca. 5 cal ka BP. Our findings highlight the influence of the latitudinal position of the westerlies, the high-pressure cell, and the SIOCZ in driving climatological and environmental changes in eastern South Africa.

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“…4g). The lithology of core MF4-12 does not exactly match with that observed from core SL6 (Baker et al, 2014;2016;, although sandy peat is observed during the LGM at both locations. This result is not surprising, multiple cores taken in transects across the bog indicate peat heterogeneity (Grundling et al, 2013).…”

Section: Resultsmentioning

confidence: 66%

The drivers of late Quaternary climate variability in eastern South Africa

Miller

Finch

Hill

et al. 2019

Preprint

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Abstract. The scarcity of continuous, terrestrial, palaeoenvironmental records in eastern South Africa leaves the evolution of late Quaternary climate and its driving mechanisms uncertain. Here we use a ~ 7-m long core from Mfabeni peatland (KwaZulu-Natal, South Africa) to reconstruct climate variability for the last 32 thousand years (ka BP). We infer past vegetation and hydrological variability using stable carbon (𝛿13Cwax) and hydrogen isotopes (𝛿Dwax) of plant-wax n-alkanes and use Paq to reconstruct water table changes. Our results indicate that late Quaternary climate in eastern South Africa did not respond directly to orbital forcing nor to changes in sea surface temperatures (SSTs) in the western Indian Ocean. The arid conditions evidenced at Mfabeni during the Last Glacial Maximum (LGM) are a consequence of both low SSTs and an equatorward displacement of the southern hemisphere westerlies due to increased Antarctic sea ice extent. The increased humidity at Mfabeni between 19–14 ka BP likely resulted from decreased Antarctic sea ice which led to a southward retreat of the westerlies and increased the influence of the moisture-bearing tropical easterlies. Between 14–5 ka BP, when the westerlies were in their southernmost position, local insolation became the dominant control, leading to stronger atmospheric convection and an enhanced tropical easterly monsoon. Generally drier conditions persisted during the past c. 5 kyrs, but were overlain by high amplitude, millennial-scale environmental variability, probably resulting from an equatorward return of the southern hemisphere westerlies and heightened ENSO activity. Our findings stress the influence of the southern hemisphere westerlies in driving climatological and environmental changes in eastern South Africa.

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Fluctuations of vegetation and climate over the last 75 000 years in the Savanna Biome, South Africa: Tswaing Crater and Wonderkrater pollen sequences reviewed

Cited by 40 publications

References 59 publications

temperature index in a Late Quaternary sequence at Wonderkrater, South Africa

temperature index in a Late Quaternary sequence at Wonderkrater, South Africa

Late Quaternary climate variability at Mfabeni peatland, eastern South Africa

The drivers of late Quaternary climate variability in eastern South Africa

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