The Climate-Environment-Society Nexus in the Sahara from Prehistoric Times to the Present Day

The Sahara is a key region for studies of archaeology, human-environment interaction, global biogeochemical cycles, and global climate change. With a few notable exceptions, the region is the subject of very little international scientific research, a fact that is remarkable given the Sahara's proximity to Europe, the developmental issues facing its growing population, the region's sensitivity to climate change and the Sahara's potential for influencing global climate through the export of airborne mineral dust. This article seeks to address human-environment interaction in the Sahara from an interdisciplinary perspective, focusing on the implications of Saharan environmental variability and change for human populations both within and outside of the region on timescales ranging from decades to millennia. The article starts by addressing past climatic changes and their impacts on human populations, before moving on to consider present day water resources and rainfall variability in their longer-term context; the possibility of a 'greening' of the southern Sahara as suggested by some climate models is also discussed. The role of the Sahara as the world's largest source of airborne mineral dust is addressed in some detail, as are the impacts of dust on climate, ecosystems and human health, as well as the implications of future changes in climate for dust production and the role of the Sahara in the Earth system. The article ends with a discussion and synthesis that explores the lessons that may be learnt from a study of the physical and social sciences in the Sahara, in particular focusing on what the signature of past environmental and socio-cultural changes can tell us about human responses and adaptations to climatic and environmental change - a matter of great relevance to researchers and policy makers alike in the context of anthropogenic climate change or 'global warming'.