Abstract. The scarcity of continuous, terrestrial, palaeoenvironmental records in
eastern South Africa leaves the evolution of late Quaternary climate and its
driving mechanisms uncertain. Here we use a ∼7 m long core
from Mfabeni peatland (KwaZulu-Natal, South Africa) to reconstruct climate
variability for the last 32 000 years (cal ka BP). We infer past
vegetation and hydrological variability using stable carbon
(δ13Cwax) and hydrogen isotopes (δDwax) of plant-wax
n-alkanes and use Paq to reconstruct water table changes. Our results
indicate that late Quaternary climate in eastern South Africa did not
respond directly to orbital forcing or to changes in sea-surface
temperatures (SSTs) in the western Indian Ocean. We attribute the arid
conditions evidenced at Mfabeni during the Last Glacial Maximum (LGM) to low
SSTs and an equatorward displacement of (i) the Southern Hemisphere
westerlies, (ii) the subtropical high-pressure cell, and (iii) the South Indian
Ocean Convergence Zone (SIOCZ), which we infer was linked to increased
Antarctic sea-ice extent. The northerly location of the high-pressure cell
and the SIOCZ inhibited moisture advection inland and pushed the
rain-bearing cloud band north of Mfabeni, respectively. The increased
humidity at Mfabeni between 19 and 14 cal kyr BP likely resulted from a
southward retreat of the westerlies, the high-pressure cell, and the SIOCZ,
consistent with a decrease in Antarctic sea-ice extent. Between 14 and 5 cal kyr BP, when the westerlies, the high-pressure cell, and the SIOCZ were in
their southernmost position, local insolation became the dominant control,
leading to stronger atmospheric convection and an enhanced tropical easterly
monsoon. Generally drier conditions persisted during the past ca. 5 cal ka BP,
probably resulting from an equatorward return of the westerlies, the
high-pressure cell, and the SIOCZ. Higher SSTs and heightened El Niño–Southern Oscillation (ENSO) activity
may have played a role in enhancing climatic variability during the past
ca. 5 cal ka BP. Our findings highlight the influence of the latitudinal
position of the westerlies, the high-pressure cell, and the SIOCZ in driving
climatological and environmental changes in eastern South Africa.
Late Quaternary micromammals and the precipitation history of the southern Cape, South Africa: response to comments by F. Thackeray, Quaternary Research 95, 154–156
