The massive scale of the refugee crisis driven by five years of war in Syria highlights the urgency of the much broader challenge posed by population displacement to the international system. Global displacement has now reached a higher level than it has been since World War II. An effective response requires understanding not just why populations become displaced but also when. The experience of Somalia suggests that the expectation of changes of balance of power on the ground, not the actual territorial gains or the entry or exit of foreign powers, is the crucial trigger for population displacement.
There are actually very different types of refugee flows, which require quite different policy responses. Sometimes displacement occurs in massive floods, like when more than 200,000 people crossed from Rwanda into Tanzania within a 24-hour period April 29, 1994. In other cases, we see the nature of refugee flows change over time. For instance, Syria saw displacement in relatively small trickles in 2011 and part of 2012, but then a massive flood of refugees later in the conflict.
What factors influence the timing of displacement? Why do certain crises prompt displacement floods while others only elicit a trickle? Unique daily internal displacement data from Somalia in the mid-2000s, which I published in a recent article, can offer insights into these critical policy questions. Since Ethiopia’s 2006 invasion, Somalia has produced some of the world’s largest displacement flows. As Anna Lindley observes, two-thirds of Mogadishu’s population fled between the end of 2006 and the end of 2008. Somali displacement flows furthermore exhibit substantial variation over time. Its lessons may be more broadly applicable, since Somalia contains characteristics that exist in many cases of civil conflict: a weak state, proliferation of armed groups and militias, protracted conflict, poverty, and environmental challenges.