A 25,000 year record of climate and vegetation change from the southwestern Cape coast, South Africa

Abstract

The southwestern Cape of South Africa is a particularly dynamic region in terms of long-term climate change. We analysed fossil pollen from a 25,000 year sediment core taken from a near-coastal wetland at Pearly Beach that revealed that distinct changes in vegetation composition occurred along the southwestern Cape coast. From these changes, considerable variability in temperature and moisture availability are inferred. Consistent with indications from elsewhere in southwestern Africa, variability in Atlantic Meridional Overturning Circulation (AMOC) was identified as a strong determinant of regional climate change. At Pearly Beach, this resulted in phases of relatively drier conditions (~24–22.5 cal ka BP and ~22–18 cal ka BP) demarcated by brief phases of increased humidity from ~24.5–24 cal ka BP and 22.5–22 cal ka BP. During glacial Termination I (~19–11.7 ka), a marked increase in coastal thicket pollen from ~18.5 to 15.0 cal ka BP indicates a substantial increase in moisture availability, coincident, and likely associated with, a slowing AMOC and a buildup of heat in the southern Atlantic. With clear links to glacial and deglacial Earth system dynamics and perturbations, the Pearly Beach record represents an important new contribution to a growing body of data, providing insights into the patterns and mechanisms of southwestern African climate change.

Quaternary Vegetation Dynamics – The African Pollen Database

“…As pollen is found within the LGM sections of records from the western interior (e.g. the Pakhuis Pass and De Rif hyrax midden records (Quick et al 2011;Scott and Woodborne 2007a, b;) and the southwestern Cape coast within the modern WRZ (Pearly Beach record (Quick et al, 2021), the lack of preservation seems to be confined to the year-round rainfall portion of the southern Cape (Southern Cape subregion, Figure 1) and therefore likely to be tied to subregion-scale changes in moisture availability. This theory can be tested with the acquisition of new sites from both the coast and the interior.…”

<i>crestr</i>: an R package to perform probabilistic climate reconstructions from palaeoecological datasets

“…Sensitivities to other variables can also be expected but are not considered in this study. Similar sensitivity inferences can be made to define a list of temperature-sensitive taxa to reconstruct MAT (Chevalier and Chase, 2015;Chevalier et al, 2021a) or support qualitative interpretations of palaeoecological datasets (Chevalier et al, 2021b;Quick et al, 2021). A complementary diagnostic plot to assess climate sensitivities is the "violinPDFs" (Fig.…”

“…The crestr package has been designed for two independent but complementary modelling purposes. The probabilistic proxy-climate responses can be used to quantitatively reconstruct climate from their statistical combination, such as in Chevalier et al (2021a) or Chevalier and Chase (2015), or they can be used in a more qualitative way to determine the (relative) climate sensitivities of different taxa in a given area to characterise past ecological changes, such as in Chevalier et al (2021b) or Quick et al (2021). To simplify access to the functionalities, default values are provided for all parameters to enable a rapid generation of preliminary results that users can then use as a starting point to adapt the model to their data.…”

crestr An R package to perform probabilistic climate reconstructions using fossil proxies

“…Sensitivities to other variables can also be expected but are not considered in this study. Making such sensitivity inferences can be key to define a list of taxa that can be used to reconstruct temperature (Chevalier and Chase (2015), ), but also to support qualitative interpretations of palaeoecological datasets (Chevalier et al (in press), Quick et al (2021)).…”

“…climate responses can be used to quantitatively reconstruct climate from their statistical combination, such as in orChevalier and Chase (2015), or, alternatively, they can be used in a more qualitative way to determine the (relative) climate sensitivities of different taxa in a given area to characterise past ecological changes, such as inChevalier et al (in press) orQuick et al (2021). For a simpler access to the different functionalities, default values are provided for all parameters to enable a rapid generation of preliminary results that users can then use as a starting point to fine-tune the model to theirhttps://doi.org/10.5194/cp-2021-153 Preprint.…”