High-resolution record of Holocene climate change dynamics from southern Africa's temperate-tropical boundary, Baviaanskloof, South Africa

Abstract

South Africa's southern Cape is a highly dynamic climatic region that is influenced by changes in both temperate and tropical atmospheric and oceanic circulation dynamics. Recent research initiatives suggest that the major elements of the regional climate system have acted both independently and in combination to establish a mosaic of distinct climate regions and potentially steep climate response gradients across the southern Cape. To consider this further, we present new high resolution δ13C and δ15N data from a rock hyrax (Procavia capensis) midden from Baviaanskloof, in the Cape Fold Mountains of South Africa's Eastern Cape Province. Spanning the last 7200 years, these data provide detailed information regarding environmental changes in the mid- and late Holocene, allowing us to assess the spatio-temporal nature of climate change anomalies across the wider region. Throughout the full duration of the record, a negative correlation between humidity and palaeotemperature reconstructions from nearby Cango Cave is observed. In conjunction with correlations with Southern Ocean sea-surface temperatures and sea-ice presence, we infer a dominant influence of the southern westerlies in determining multi-millennial scale hydroclimate variability. At shorter, multi-centennial to millennial timescales, the Baviaanskloof data indicate a clearer expression of tropical influences, highlighting a delicate balance between the mechanisms driving regional climate dynamics across timescales, and the sensitivity of the region to changes in global boundary conditions.