The consequences of past climate change for state formation and security in southern Africa

Abstract

Considerable research has been undertaken into the nature and consequences of contemporary and future global climate change, yet detailed regional studies concerning these dynamics prior to the twentieth century have only recently begun to emerge. This thesis investigates this historical climate-society interface over a c. 400- year period of socio-political change in southeast Africa. This spans the development, expansion and impoverishment of African state structures, and the arrival of the Portuguese and its impacts, between c. 1450-1830 in the Zambezi-Limpopo region, and the origins and events of socio-political transformation between c. 1760-1828 in the KwaZulu-Natal area. Previous hypotheses have proposed causal relationships between precipitation variability and this societal change, though these are predominantly built upon an apparent coincidence between the inferences of a narrow range of datasets. This cross-disciplinary study therefore reframes this research area by placing the interlinked concepts of vulnerability and resilience at the centre of its approach to tie past climate variability and societal development. First, past climate variability is evaluated using a wide range of proxy-documentary precipitation records over the last millennium, and then reconstructed using wind data from ships’ logbooks in the early-nineteenth century. This analysis reveals good agreement between sources on the evolution of precipitation variability. Similarly, palaeoclimatic, written and oral sources display strong coherence between the increased variability of precipitation and recorded climate impacts, such as in the onset and amelioration of Little Ice Age cool-dry conditions in the 1570s-1590s and 1790s-1820s. While this suggests that direct climatic-induced stress increased in times of regional or global climatic change, extensive analysis of food security, livelihoods and socio-political vulnerability from written and oral sources indicates that longer-term, structural vulnerabilities of individuals and communities were crucial in conditioning the plurality of human responses to and the overall significance of past climate variability across southeast Africa