Climate variability off Africa’s southern Cape over the past 260 000 years

During the late Quaternary, the climatic conditions in southern South Africa experienced significant fluctuations, notably in temperatures and precipitation. These fluctuations were related to changes in the atmospheric and
oceanic circulation systems from the subtropics and mid latitudes, which are themselves affected by changes in orbital parameters. At the same time, this region preserves some of the most abundant Middle Stone Age (MSA) archaeological sites containing records of Homo sapiens behavioural and
technological evolution. Consequently, there is a pressing need for precise climatic reconstructions that can provide climate constraints for the region’s MSA record. However, there is a lack of continuous high-resolution climate records covering the majority of the MSA period, which spans ∼ 300 to
∼ 40 ka. In this study, we present data obtained from a marine sediment core (MD20-3592) that spans approximately the last 260 000 years (from marine isotope stages (MISs) 8 to 1) aiming to expand the spatial and temporal coverage of available climate archives in this region (including sediment cores, speleothems and hyrax middens). This marine sediment core documents both terrestrial hydroclimate and ocean variability because it is strategically positioned close to the South African coastline receiving terrestrial sediments
via riverine input as well as being located under the marine influence of the Agulhas Current at the same time. X-ray fluorescence (XRF) core scanning, calibrated with discrete samples analysed by XRF spectroscopy, was used to determine the variability in the bulk elemental composition of the core
over time. Spectral analyses reveal that the regional hydroclimate was mostly affected by local insolation changes caused by orbital precession and high-latitude forcing that varies on timescales associated with orbital obliquity and eccentricity. Increased fluvial input was associated with high local insolation due to the effects of precession on local convergence and seasonal rainfall. Comparison with other regional climate archives as mentioned confirmed the dominant influence of precession on precipitation in southern South Africa.
On glacial–interglacial timescales, lower precipitation observed during glacial intervals could be explained by a northward shift in the Southern Hemisphere Westerlies (SHW) and South Indian Ocean Convergence Zone (SIOCZ). Finally, the data from core MD20-3592 can provide a climatic context for archaeological evidence in South Africa during the MSA.