We present new high-resolution oxygen isotope (δ18O) records from three NW African speleothems located at ~31°N. The present-day rainfall patterns at 31°N in NW Africa are linked to negative winter North Atlantic Oscillation phases. However, on multimillennial time scales, our δ18O records, together with other hydroclimate records, provide new evidence of humid conditions during the mid-Holocene, a period that was presumably characterized by arid climate. Thus, the apparent increase in moisture during the mid-Holocene is interpreted better as an increase in summer rainfall. This is most likely linked to the expansion of the West African summer monsoon fringe during the African Humid Period, which terminated in our record abruptly around 4 Kyr BP. The temporospatial difference with speleothem records from N Morocco suggests that the High-Atlas Mountains might have been a topographic barrier to further expansion of the West African summer monsoon fringe into higher latitudes.
Bibliographical noteFunding Information:
This work was supported by grants from NSFC (41888101, 41472140, 41731174, and 41561144003), U.S. NSF Grant 1702816, and the Postdoctoral Science Foundation of China (Grant 2018M640971) to Yassine Ait Brahim.
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- African Humid Period
- West African summer monsoon
- abrupt climate change
- speleothem δO records