Three Hundred Thousand Years of Multi-Millennial Hydroclimate Variability in Northern Africa Revealed by Tunisian Speleothems

Hydroclimate variability in northern Africa, driven by the interactions between the mid-latitude westerlies and the West African Monsoon (WAM) and by variations in their intensity, represents a key control on hominin dispersal. However, the response of these atmospheric circulation systems to changing boundary conditions and their influence on precipitation during past climate states remain poorly constrained, largely because most well-dated terrestrial hydroclimate records are limited to the Holocene interglacial period. Here, we present a 300,000-year hydroclimate record from northernmost Africa based on speleothem growth in Tunisia. This record captures alternating humid and arid phases across multiple glacial–interglacial cycles, as well as superimposed millennial-scale variability. Speleothem growth occurred predominantly during interglacials, indicating humid conditions, whereas growth hiatuses correspond to arid glacial periods. The cave record suggests that humid phases in northernmost Africa were primarily driven by a southward displacement and intensification of the mid-latitude westerlies and the Mediterranean storm track during interglacials. Comparison with Saharan palaeolake records further indicates that both enhanced winter westerlies and a strengthened summer WAM were required to generate widespread wet conditions across northern Africa during interglacial periods. These results highlight the combined influence of winter and summer moisture sources in shaping long-term hydroclimate variability and defining habitable corridors across northern Africa over the past 300,000 years.