Climate, Terrain, Refugees and Interstate War
"The Effects of Temperature on Political Violence: Global Evidence at the Subnational Level"
w/ Alex Bollfrass.
PLOS ONE
Statistical results showing that absolute temperature level is significantly and positively correlated with incidence of conflict around the world. This relationship manifests in both non-agricultural and agricultural sample provinces.
A number of studies have demonstrated an empirical relationship between higher ambient temperatures and substate violence, which have been extrapolated to make predictions about the security implications of climate change. This literature rests on the untested assumption that the mechanism behind the temperature-conflict link is that disruption of agricultural production provokes local violence. Using a subnational-level dataset, this paper demonstrates that the relationship: (1) obtains globally, (2) exists at the substate level — provinces that experience positive temperature deviations see increased conflict; and (3) occurs even in regions without significant agricultural production. Diminished local farm output resulting from elevated temperatures is unlikely to account for the entire increase in sub- state violence. The findings encourage future research to identify additional mechanisms, including the possibility that a substantial portion of the variation is brought about by the well-documented direct effects of temperature on individuals' propensity for violence or through macroeconomic mechanisms such as food price shocks.
"Places to Hide: Terrain, Ethnicity, and Political Violence"
Journal of Politics.
Terrain ruggedness and the location of Fuerzas Armadas Revolucionarias de Colombia bases in 1964 (left) and 1995 (right).
Terrain is central to understanding why some countries have contentious ethnic divisions, while others do not. We argue that access to variable rugged terrain facilitated the development and survival of more distinct ethnic groups, even in the face of government repression. The persistence of greater ethnic diversity in highly variable rugged areas as well as the tendency for these ethnic groups to be politically excluded is also associated with civil war. Specifically, ethnicity mediates some of the eect that terrain has on civil war, a point overlooked by most of the literature. Using province-level geo-coded data on civil war, terrain and both the distribution and political status of ethnic groups, we demonstrate that rugged variable terrain directly and indirectly aects the incidence of civil war. A substantively important proportion of terrain's effects on civil conict are transmitted indirectly through the distribution and exclusion of politically relevant ethnic groups.
"Do Refugees Spread Conflict?"
w/ Yang-Yang Zhou.
Statistical results showing that, contrary to population belief, those subnational areas of the world that receive refugee communities experience a reduction in their subsequent conflict likelihood.
As the number of forcibly displaced individuals around the world continues to reach record highs, understanding how their presence affects conflict is a major outstanding academic and policy question. Using new geo-coded data on refugee sites and civil conflict data at the subnational level from 1989 to 2008, we find no support for claims that refugees increase the likelihood of civil conflict where they settle. Moreover, we find that provinces hosting refugee sites experience substantively large decreases in their likelihood of civil conflict, when there are no other provinces hosting refugee sites within the same country for a given year. We confirm these findings when examining heterogeneous effects of formal refugee camps and informal settlements. To exclude the possibility of selection on unobserved confounders, we use placebo tests to show that there are no effects of future refugee sites on conflict outcomes.
"Civil war violence and refugee outflows"
w/ James Fearon.
Conflict forces millions of individuals from their homes each year, but surprisingly little research exists on violence and forcible displacement at the global level. Using a simple structural model and new refugee data, we produce the first set of estimates relating outflows to annual conflict magnitudes. The theory underlying the structural model implies that standard panel data approaches will underestimate the impact of conflict violence, by “differencing out” the effect of prior and expected levels of violence on the decisions to flee. We estimate that whereas a shock that doubles conflict deaths in one year increases outflows in that year by 40% on average, doubling conflict deaths in all years increases annual outflowws by 100%. We further estimate an average of 30 refugees per conflict death (median 18), with higher rates for conflict closer to an OECD country and possibly for ethnic wars and in lower income countries. The analysis illustrates a broader methodological point: It is hazardous to try to identify a causal effect using shocks to a presumed causal factor if the outcome variable is the result of decisions based not only on shocks but also on levels.