South African speleothems reveal influence of high- and low-latitude forcing over the past 113.5 k.y.

Variation in delta 18O and delta C-13 values in a speleothem from the Cango Caves in southernmost South Africa enable the construction of coherent regional composite records spanning the past 113,500 yr. Novel for the region in terms of both their length and detail, these records indicate environmental and climatic changes that both are consistent with records from the wider region and show a clear evolution from low- to high-latitude forcing dominance across the last glacial period. Prior to ca. 70 ka, the influence of direct low-latitude insolation forcing is expressed through increases in summer rainfall during austral summer insolation maxima. With the onset of Marine Isotope Stage 4, cooler global conditions and the development of high-latitude ice sheets appear to have supplanted direct insolation forcing as the dominant driver pacing patterns of environmental change, with records from the Southern and Northern Hemisphere tropics exhibiting a positive relationship until after the Last Glacial Maximum. These results highlight the complexity of South African climate change dynamics as a response to changing global boundary conditions and provide a critical reference for regional and global comparisons.

Automated summary

This study examines the variation in oxygen and carbon isotope values in a speleothem from the Cango Caves in southernmost South Africa, establishing a coherent regional composite record spanning the past 113,500 years. The findings reveal a complex dynamic of South African climate change, influenced by both changing global boundary conditions and environmental forcing factors from low and high latitudes.