Geologist commonly use speleothem δ¹⁸O_c records to reconstruct past North African monsoon variability based on “amount effect” relationship between δ¹⁸O_c and monsoon rainfall. However, the interpretation of these records has been challenged in recent years. Here, we use isotope-enabled climate model to simulate climate change during the past 150,000 years. We find that changes in δ¹⁸O_p across North African region are caused by multiple atmospheric processes, rather than by “amount effect”.