During the early Holocene, northern Africa was relatively humid and supported a large human population. Around 5,500 years ago (5.5 ka) the regional climate deteriorated and the population declined substantially. Evidence suggests these changes were coeval, but it is unclear whether or not humans influenced this ecological collapse. Using a climate-vegetation model driven by global forcings, we forecast the length of the Holocene African Humid Period (AHP). The model indicates that the system was most likely to collapse between 7-6 ka, which is at least 500 years before the observed collapse. Archaeological and ethnographic evidence from northern Africa, suggests that the shift from hunter-gatherer to pastoralist societies around 7 ka was an effective adaptation to the orbitally-driven regional environmental changes. The pastoralist strategy may even have slowed the deterioration caused by orbital driven climate change. This supports the view that modern pastoralists are beneficial for the management of the world’s dryland environments.
I am interested in how the climate evolved in the past and will do so going into the future. Like the climate, my career path has steadily evolved since its start in physics (BSc, Durham, 2002). I then studied coupled climate modelling (PhD in Meteorology, University of Reading, 2007), which combines physical oceanography with atmospheric physics. A post-doc in the Geology & Geophysics department at Yale exposed me to the true scale of Earth history. I am especially in how we can use studies of past climate variability to quantify the uncertainty in future projections.