REGIONAL PATTERNS IN THE LATE QUATERNARY PALAEOENVIRONMENTS OF THE SOUTHWESTERN CAPE, SOUTH AFRICA

The southwestern Cape of South Africa experiences a winter-rainfall climate regime but is characterised by extreme environmental heterogeneity such that annual quantities and temporal distribution of precipitation are highly variable. Large expanses of the region are semi-arid. Elucidation of Quaternary palaeoenvironments is regarded as important because the region is associated with prolific levels of biological diversity, especially within a flora that has been designated as one of only six Floristic Kingdoms globally. The archaeological record provides an additional motivation to reconstruct environments of the past. Furthermore, long-term environmental changes in the region may provide vital clues as to the behaviour of the global thermohaline conveyor belt, which passes offshore in both directions and which is a major sub-Milankovitch scale mechanism of global climate change. Quaternary environmental reconstruction has been hampered by the absence of long, continuous terrestrial sedimentary archives, but many shorter, temporally fragmented, records exist for a variety of habitat types in the region. These records are employed in this paper to develop a model of evolving palaeoenvironments from the Last Glacial Maximum (LGM) and through the Holocene. They reveal that different geographical areas within the winter-rainfall region as a whole, may have reacted differently under dynamic environmental circumstances over the period in question. Nevertheless, there is an emerging pattern of cooler and wetter LGM conditions across much of the region, contrasting markedly with equivalent sites in the all-year and summer-rainfall regions of southern Africa. This may have particular significance in light of the implications of substantially reduced partial pressures of atmospheric carbon dioxide at the time. Holocene environmental conditions appear also to have been spatially and temporally variable. Since European colonisation, anthropogenic change has emerged as the dominant environmental signal. Evidence from the late Quaternary of the southwestern Cape may now be sufficiently resolved to facilitate its use, through comparison with regionally-downscaled climate model outputs, in developing climate change predictions.