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Did pastoralism hold back desertification of the Sahara?

Nature Communications report of UCL Geography study

Did pastoralism hold back desertification of the Sahara?

During the African humid period (AHP), before the desertification of the Sahara, evidence points to human population expansion in northern Africa and the introduction of pastoralism.

A new paper in Nature Communications by UCL Geography’s Dr Chris Brierley and Professor Mark Maslin, with Dr Katie Manning of King’s College, London, examines the possible role of this population growth in the subsequent ecological collapse.

A model is developed to predict the effects of orbital forcing during the Holocene on climate-vegetation feedbacks and the drying of the Sahara. It is concluded that the natural end of the AHP should have been around 6,000 year ago, about 500 years earlier than suggested by reconstructions of actual climate change. So why the difference in timing?

While it has been suggested that increases in Saharan pastoralism around 6000 years ago accelerated desertification, a beneficial relationship is actually indicated by evidence for how pastoralists interact with the environment. It seems that the Saharan population did the right things to combat desertification at a most sensitive time - increasing pastoralism became an effective adaptation to environmental change. The system therefore stayed 'green' for longer.

Such a process exemplifies how humans can live sustainably with the Earth System, and shows how efforts such as the World Initiative on Sustainable Pastoralism offer real promise in holding back aridification, rather than simply assuming the inevitability of climate changes.


See also:


Flowchart of human delaying effects

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Chris Brierley
Mark Maslin