Manuscripts 2014
The effects of temperature and precipitation variability on the risk of violence in sub-Saharan Africa, 1980-2012
O'Loughlin, J., A. Linke, F. Witmer
Proceedings of the National Academy of Sciences 111(47):16712-16717 (2014).
Abstract:
Ongoing debates in the academic community and in the public policy arena continue without clear resolution about the significance of global climate change for the risk of increased conflict. Sub-Saharan Africa is generally agreed to be the region most vulnerable to such climate impacts. Using a new database of conflict events and detailed climatological data covering the period 1980-2012, we employ a multilevel modeling technique that allows for a more nuanced understanding of a climate-conflict link than has been seen heretofore. In the aggregate, high temperature extremes are associated with more conflict; however, different types of conflict and by different sub-regions do not show consistent relationship with temperature deviations. Precipitation deviations, both high and low, are generally not significant. The location and timing of violence are influenced less by climate anomalies (temperature or precipitation variations from normal) than by key political, economic and geographic factors. We find important distinctions in the relationship between temperature extremes and conflict by using different methods of analysis and by exploiting our large time-series cross-sectional dataset for disaggregated analyses.
Modeling and data choices sway conclusions about climate-conflict links
O'Loughlin, J., A. Linke, F. Witmer
Proceedings of the National Academy of Sciences 111(6):2054-2055 (2014).
Manuscripts 2012
Climate variability and conflict risk in East Africa, 1990-2009
O'Loughlin, J., F. Witmer, A. Linke, A. Laing, A Gettelman, and J. Dudhia
Proceedings of the National Academy of Sciences 109(45): 18344-18349 (2012).
Abstract:
Recent studies concerning the possible relationship between climate
trends and the risks of violent conflict have yielded contradictory
results, partly because of choices of conflict measures and modeling
design. In this study, we examine climate-conflict relationships using
a geographically disaggregated approach. We consider the
effects of climate change to be both local and national in character,
and we use a conflict database that contains 16,359 individual geolocated
violent events for East Africa from 1990 to 2009. Unlike
previous studies that relied exclusively on political and economic
controls, we analyze the many geographical factors that have been
shown to be important in understanding the distribution and causes
of violence while also considering yearly and country fixed effects.
For our main climate indicators at gridded 1° resolution (~100 km),
wetter deviations from the precipitation norms decrease the risk of
violence, whereas drier and normal periods show no effects. The
relationship between temperature and conflict shows that much
warmer than normal temperatures raise the risk of violence,
whereas average and cooler temperatures have no effect. These
precipitation and temperature effects are statistically significant
but have modest influence in terms of predictive power in a model
with political, economic, and physical geographic predictors. Large
variations in the climate-conflict relationships are evident between
the nine countries of the study region and across time periods.
