Tropical forcing and ENSO dominate Holocene climates in South Africa's southern Cape
Résumé
This paper explores the Holocene climatic dynamics of South Africa’s southern Cape, a region that supports a
large proportion of the Greater Cape Floristic Region and contains an array of important archaeological sites.
While South African climates are generally characterised by marked rainfall seasonality, the southern Cape is
currently situated at the interface between tropical and temperate climate systems, resulting in a largely aseasonal
rainfall regime. This regime, however, is thought to have been particularly sensitive to past changes in late
Quaternary boundary conditions, meaning that variability in either tropical or temperate systems could have
significant environmental impacts. Evidence of past climate change, however, remains limited.
We present a 9000-year record of hydroclimatic variability obtained from rock hyrax midden stable nitrogen
records, from Papkuilsfontein, on the southern slope of the Anysberg Mountains. Resolved to an average 6-year
resolution and spanning the period c. 9050 cal yr BP to 1990 CE, this is the highest resolution Holocene record
from southern Africa and presents a unique opportunity for the detailed study of the primary drivers and spatial
gradients of Holocene climate change in the southern Cape. The data indicate a long-term decrease in aridity
across the Holocene and a pattern of variability that reveals remarkable similarities with records from the South
African tropics and El Ni˜no–Southern Oscillation proxies, highlighting the significance of tropical systems as
drivers of Holocene climate change in the region. This substantially expands what has been previously considered
to be the zone of tropical influence, extending from a coastal phenomenon associated with heat transport via
the Agulhas Current to encompass much, if not all, of the Agulhas Plain south of the Cape Fold Mountains. These
findings provide a valuable new climatic framework for contextualizing changes in ecological and archaeological
records in the southern Cape, and contribute to a more comprehensive understanding of the spatio-temporal
dynamics of climate systems in southern Africa.
Domaines
Climatologie
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Origine : Publication financée par une institution
Licence : CC BY NC - Paternité - Pas d'utilisation commerciale
Licence : CC BY NC - Paternité - Pas d'utilisation commerciale