A plausible deep root for Africa's problems (see also this post):
"A notable scientific contribution in establishing [the] link [between rising water stress and conflict] was made by Edward Miguel and his colleagues, who found that "drops in rainfall [in Africa] are associated with significantly more conflict...
There is strong evidence that better rainfall makes conflict much less likely in Africa."* The key link seems to be that a decline in rainfall causes the economy to shrink, presumably through the adverse effects on harvests and food supply, and this in turn triggers conflict. What is important is that when the authors compared the explanatory power of rainfall with political variables (such as democracy, ethnic cleavages, religious divisions, colonial heritage) in accounting for the location, and timing of conflicts in Africa, the rainfall variable was more important than the political variables. The research team concluded as follows: "The most obvious reading of these findings is that economic factors trump all others in causing African civil conflicts, and that institutional and political characteristics have much less of an impact."**"
* Edward Miguel, Shanker Satyanath, and Ernest Sergent, "Economic Shocks and Civil Conflict: An Instrumental Variables Approach", Journal of Political Economy 112, no. 4 (2004), pp. 725-753.
** Edward Miguel, "Poverty and Violence", in Lael Brainard and Derek Chollet, eds., Too Poor for Peace? Global Poverty, Conflict and Security in the 21st Century (Washington, D.C.: Brookings Institute Press, 2007), p. 55.
Jeffrey Sachs, Common Wealth, Economics for a crowded planet, chapter "Securing our water needs".
This is a very worrying relationship, as water stress is forecasted to increase in many places on Earth, as global warming intensifies ! As Jeffrey Sachs adds:
"Water scarcity is, so far, mainly responsible for conflicts within countries rather than between them, yet cross-border confrontations will also become more likely to arise as water stress becomes more extreme."