Linking upwelling intensity and orbital-scale climate variability in South Africa's winter rainfall zone: Insights from a ca. 70,000-year hyrax midden record - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Quaternary Science Advances Année : 2023

Linking upwelling intensity and orbital-scale climate variability in South Africa's winter rainfall zone: Insights from a ca. 70,000-year hyrax midden record

Résumé

The climate of Africa's southwestern Cape is characterised by a strongly seasonal winter precipitation regime, with late Quaternary climate variability generally considered to have been driven by the position of the southern westerlies. This paper presents a unique ~70,000 year-long palaeoclimatic record from a rock hyrax midden from South Africa's winter rainfall zone, enabling the analysis of regional climate systems since the beginning of marine isotope stage 4. The data suggest that the last glacial period was relatively humid compared to the Holocene, likely due to cooler temperatures, more extensive Antarctic sea-ice extent and an equatorward displacement of the westerly storm track. However, orbital-scale climate variability associated with the 23 kyr precessional cycle primarily correlates with changes in upwelling intensity in the Benguela system, implying an important role for the blocking of tropical easterly flow in driving long-term climatic variability. These factors combined during glacial periods to significantly amplify rainfall seasonality in the southwestern Cape, bringing more winter rainfall via mid-latitude frontal systems, while reducing the proportion of summer rainfall, particularly during the glacial periods of the late Quaternary. The results therefore highlight the need to consider a complex suite of circulation systems and dynamics when inferring drivers of long-term environmental change in the region.
Fichier principal
Vignette du fichier
Chase et al 2023_QSA_70 kyr Groenfontein upwelling & WRZ.pdf (8 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Licence : CC BY NC ND - Paternité - Pas d'utilisation commerciale - Pas de modification

Dates et versions

hal-04180429 , version 1 (15-09-2023)

Identifiants

Citer

Brian M Chase, Andrew S Carr, Arnoud Boom, Genevieve Tyrrell, Paula J Reimer. Linking upwelling intensity and orbital-scale climate variability in South Africa's winter rainfall zone: Insights from a ca. 70,000-year hyrax midden record. Quaternary Science Advances, 2023, 12, ⟨10.1016/j.qsa.2023.100110⟩. ⟨hal-04180429⟩
26 Consultations
15 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More