Publication Date:
2024-03-06
Description:
The present-day condition of bipolar glaciation characterized by rapid and large climate fluctuations began at the end of the Pliocene with the intensification of the Northern Hemisphere continental glaciations. The global cooling steps of the late Pliocene have been documented in numerous studies of Ocean Drilling Program (ODP) sites from the Northern Hemisphere. However, the interactions between oceans and between land and ocean during these cooling steps are poorly known. In particular, data from the Southern Hemisphere are lacking. Therefore I investigated the pollen of ODP Site 1082 in the southeast Atlantic Ocean in order to obtain a high-resolution record of vegetation change in Namibia between 3.4 and 1.8 Ma. Four phases of vegetation development are inferred that are connected to global climate change. (1) Before 3 Ma, extensive, rather open grass-rich savannahs with mopane trees existed in Namibia, but the extension of desert and semidesert vegetation was still restricted. (2) Increase of winter rainfall dependent Renosterveld-like vegetation occurred between 3.1 and 2.2 Ma connected to strong advection of polar waters along the Namibian coast and a northward shift of the Polar Front Zone in the Southern Ocean. (3) Climatically induced fluctuations became stronger between 2.7 and 2.2 Ma and semiarid areas extended during glacial periods probably as the result of an increased pole-equator thermal gradient and consequently globally enhanced atmospheric circulation. (4) Aridification and climatic variability further increased after 2.2 Ma, when the Polar Front Zone migrated southward and the influence of Atlantic moisture brought by the westerlies to southern Africa declined. It is concluded that the positions of the frontal systems in the Southern Ocean which determine the locations of the high-pressure cells over the South Atlantic and the southern Indian Ocean have a strong influence on the climate of southern Africa in contrast to the climate of northwest and central Africa, which is dominated by the Saharan low-pressure cell.
Keywords:
175-1082; Abrus; Abutilon; Acacia/Parkia; Acanthaceae; Afrormosia; AGE; Aizoaceae; Alchornea; Allanblackia; Aloe-type; Amaranthaceae/Chenopodiaceae; Antidesma-type; Araliaceae undifferentiated; Arctotis-type; Arecaceae; Asphodelus; Balanites; Baphia-type; Barleria; Benguela Current, South Atlantic Ocean; Bignoniaceae; Blepharis; Blighia-type; Bombax; Borassus-type; Borreria; Boscia-type; Bosqueia; Boswellia; Botryococcus; Brachystegia; Brassicaceae; Bridelia; Burkea; Butyrospermum; Cadaba; Calligonum; Calycobolus-type; Caperonia; Caryophyllaceae; Cassia-type; Celastraceae/Hippocrateaceae; Celtis; Centaurea (Africa); Center for Marine Environmental Sciences; Chrozophora; Chrysophyllum; Cissus; Clematis-type; Cleome; Clutia; Cnestis-type; Coccinia; Coffea-type; Cola cordifolia; Colophospermum mopane; Combretaceae/Melastomataceae; Commiphora; COMPCORE; Compositae Liguliflorae; Compositae Tubuliflorae; Compositae Vernonieae; Composite Core; Corchorus; Counting, palynology; Crossopteryx; Cucurbitaceae; Cuviera; Cyperaceae undifferentiated; Daisy-type; Daniellia-type; Depth, composite; DEPTH, sediment/rock; Detarium; Dialium-type; Diodia-type; Diospyros; Dodonaea viscosa; Dorstenia; Dracaena; DSDP/ODP/IODP sample designation; Ecbolium; Entada-type; Ericaceae undifferentiated; Erythrina; Eugenia/Syzygium; Euphorbiaceae undifferentiated; Euphorbia-type; Fagonia; Fern spores; Gazania-type; Gomphrena-type; Grewia; Heliotropium; Heritiera-type; Hermannia; Hibiscus-type; Hygrophila-type; Hymenocardia; Hyphaene; Hypoestes type; Icacinaceae undifferentiated; Ilex cf.. mitis; Indeterminata/varia; Indigofera-type; Intercore correlation; Iodes; Irvingia; Isoberlinia-type; Ixora; Jasminum; Joides Resolution; Justicia/Monechma; Kedrostis; Khaya; Klaineanthus; Lannea; Leea; Leg175; Liliaceae undifferentiated; Lophira; Luffa; Lythraceae; Maerua-type; Mallotus; Manilkara; Marker, added; Marker, found; MARUM; Meliaceae; Melochia; Monopetalanthus; Morinda; Myrica; Neurada/Grielum; Newbouldia; Nitraria; Nothofagus; Nyctaginaceae; Nymphaea; Ocean Drilling Program; Ocimum; ODP; Olea; Olea capensis; Ormocarpum; Pandanus; Papilionoideae; Parinari; Pavetta; Pediastrum; Peganum; Pelargonium; Pentaclethra; Pentas; Pentzia/Cotula-type; Petalidium; Phyllanthus; Piliostigma; Plantago; Plumbaginaceae undifferentiated; Poaceae undifferentiated; Podocarpus; Pollen, total; Polycarpon; Polygala-type; Polygonum aviculare-type; Polygonum senegalense-type; Portulaca; Priva; Protea; Pseudoprosopis; Pteridium; Pteris; Pterocarpus; Pycnanthus; Raphia; Restionaceae; Rhamnaceae undifferentiated; Rhizophora; Rhus-type; Rhynchosia-type; Rubiaceae tetrade; Rubiaceae undifferentiated; Rumex; Sabicea; Salvadora persica; Sample code/label; Sapotaceae; Sesbania-type; Solanum-type; Sopubia; Spathodea; Spores, monolete; Spores, trilete; Spores, trilete reticulate; Stachytarpheta; Sterculiaceae; Sterculia-type; Stereospermum; Stipularia africana; Stoebe-type; Strophanthus-type; Strychnos; Tamarindus/Cryptosepalum; Tapinanthus; Tarchonanthus/Artemisia-type; Telephium; Tephrosia; Tetraploa aristata conidia; Teucrium; Thesium; Thymelaeaceae; Tribulus; Triumfetta; Typha angustifolia-type; Uapaca; Urticaceae; Viscum; Volume; Welwitschia; Zanthoxylum; Zygophyllum
Type:
Dataset
Format:
text/tab-separated-values, 57893 data points
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