Erschienen in:
Climate of the Past, 17 (2021) 1, Seite 345-360
Sprache:
Englisch
DOI:
10.5194/cp-17-345-2021
ISSN:
1814-9332
Entstehung:
Anmerkungen:
Beschreibung:
Abstract. We present a continuous and well-resolved record of climatic variability forthe past 100 000 years from a marine sediment core taken in Delagoa Bight,off southeastern Africa. In addition to providing a sea surface temperaturereconstruction for the past ca. 100 000 years, this record also allows ahigh-resolution continental climatic reconstruction. Climate sensitive organicproxies, like the distribution and isotopic composition of plant-wax lipids aswell as elemental indicators of fluvial input and weathering type provideinformation on climatic changes in the adjacent catchment areas (Incomati,Matola and Lusutfu rivers). At the transition between glacials andinterglacials, shifts in vegetation correlate with changes in sea surfacetemperature in the Agulhas Current. The local hydrology, however, does notfollow these orbitally paced shifts. Instead, precipitation patterns followmillennial-scale variations with different forcing mechanisms in glacialvs. interglacial climatic states. During glacials, southward displacement ofthe Intertropical Convergence Zone facilitates a transmission of northernhemispheric signals (e.g., Heinrich events) to the southern hemisphericsubtropics. Furthermore, the southern hemispheric westerlies become a moredirect source of precipitation as they shift northward over the study site,especially during Antarctic cold phases. During interglacials, the observedshort-term hydrological variability is also a function of Antarctic climatevariability; however, it is driven by the indirect influence of the southernhemispheric westerlies and the associated South African high-pressure cellblocking the South Indian Ocean Convergence Zone related precipitation. As aconsequence of the interplay of these effects, small-scale climatic zonesexist. We propose a conceptual model describing latitudinal shifts of thesezones along the southeastern African coast as tropical and temperate climatesystems shift over glacial and interglacial cycles. The proposed modelexplains some of the apparent contradictions between several paleoclimaterecords in the region.