Abstract:
Climate records along aridity gradients where manifestations of
climate change are most profound are important for testing climate models. The
Kalahari Transect spans such a gradient, but instrumental records of climate
parameters are limited in the sparsely populated region. We analysed the δ13C
and δ18O record from a Vachellia erioloba (E.Mey) tree from the southern
Kalahari Desert in Botswana to explore its potential as a climate proxy archive.
Radiocarbon dates show that the record spans the period 1758-2013 CE.
Both the δ13C and δ18O records correlate with local rainfall. The isotope proxies
show a weak positive correlation with sea-surface temperature reconstruction
from the southwestern Indian Ocean, and a stronger correlation with the El Niño
Southern Oscillation index. This appears to contradict previous evidence that
higher sea-surface temperatures are associated with reduced summer rainfall
over the southern African interior. Instead of eastward shifts in the temperate
tropical trough synoptic system during elevated southwestern Indian Ocean
temperature anomalies, the evidence supports a westwards shift. The result
demonstrates the potential of Vachellia erioloba as a climate proxy archive that
may yield past climate variability from the arid regions of southern Africa.
