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Titel |
Increased aridity in southwestern Africa during the warmest periods of the last interglacial |
VerfasserIn |
D. H. Urrego, M. F. Sanchez Goñi, A.-L. Daniau, S. Lechevrel, V. Hanquiez |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1814-9324
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Digitales Dokument |
URL |
Erschienen |
In: Climate of the Past ; 11, no. 10 ; Nr. 11, no. 10 (2015-10-20), S.1417-1431 |
Datensatznummer |
250117439
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Publikation (Nr.) |
copernicus.org/cp-11-1417-2015.pdf |
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Zusammenfassung |
Terrestrial and marine climatic tracers from marine core MD96-2098 were used
to reconstruct glacial–interglacial climate variability in southwestern
Africa between 194 and 24 thousand years before present. The pollen record
documented three pronounced expansions of Nama-karoo and fine-leaved savanna
during the last interglacial (Marine Isotopic Stage 5 – MIS 5). These
Nama-karoo and fine-leaved savanna expansions were linked to increased
aridity during the three warmest substadials of MIS 5. Enhanced aridity
potentially resulted from a combination of reduced Benguela Upwelling,
expanded subtropical high-pressure cells, and reduced austral-summer
precipitation due to a northward shift of the Intertropical Convergence
Zone. Decreased austral-winter precipitation was likely linked to a southern
displacement of the westerlies. In contrast, during glacial isotopic stages
MIS 6, 4 and 3, fynbos expanded at the expense of Nama-karoo and fine-leaved
savanna indicating a relative increase in precipitation probably
concentrated during the austral winter months. Our record also suggested
that warm–cold or cold–warm transitions between isotopic stages and
substages were punctuated by short increases in humidity. Increased aridity
during MIS 5e, 5c and 5a warm substages coincided with minima in both
precessional index and global ice volume. On the other hand, austral-winter
precipitation increases were associated with precession maxima at the time
of well-developed Northern Hemisphere ice caps. |
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