During the early Holocene, northern Africa was relatively humid and supported a large human population. Around 5,500 years ago (ka), the regional climate deteriorated and the population declined significantly. Evidence suggests these changes were coeval, but it is unclear whether or not humans influenced this ecological collapse. I have developed an idealised model of the coupled climate-ecosystem, and use this to forecast the length of the Holocene African Humid Period.
The model shows that the end of the Holocene African Humid Period had a low predictability in comparison with previous instances. It also indicates that the system was most likely to collapse between 7-6 ka, which is at least 500 years before the observed collapse. This could suggest that the shift from hunter-gatherer to pastoralist human societies around 7 ka may have slowed the regional environmental deterioration caused by orbital driven climate change; supporting the emerging view that modern pastoralists are essential to the management of the world’s dryland environments.