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Introduction
• IPCC identified climate change as a threat to social stability
• Climate Change– Change in average temperature and
precipitation patterns– Change in the number and severity of climate
change related disasters• Goal
– Identify and measure the potential effects of climate change that lead to violent conflict with a goal of informing policy
Introduction
Climate Change and Civil War Civil war measures
Onset or start Incidence or occurrence Duration
Climate change related disasters Income shock channel Such events decrease the opportunity costs of
using violent conflict as a method to assert power over allocation of scarce resources
Other channels
Literature Overview
• Civil War Literature (Unrelated to Climate Change)– Blattman and Christopher (2010) Literature
Review– Fearon and Laitin (2003) Civil War Onset– Fearon (2004) Civil War Duration
• Average Temperature and Precipitation Effects on Civil War– Hendrix and Glaser (2007) average precipitation
in Africa – Burke et al. (2009) average precipitation and
temperature in Africa– Zhang et al. (2006) Low average temperatures
in China– Tol and Wagner (2010) Low average
temperatures in Europe– Miguel et al. (2004)
Literature Overview
Extreme Weather Effects on Civil War Nel and Righarts (2008) single index of
disasters on civil war onset Besley et al. (2009) theoretical model
for the civil war incidence, some empirics
No research on the impacts of climate change on civil war duration
Contribution
First study to look at the differentiated effects of variety of climate change related disasters on various measures of civil war
Quantifying the costs of climate change As such it can inform climate change
mitigation and adaptation policies
Data
Civil War Fearon and Laitin (2003) Civil War Onset
161 countries, 1945-1999 Fearon (2004) Civil War Duration
73 countries, 1945-1999 Natural Disasters
Centre for Research on the Epidemiology of Disasters (CRED) Emergency Events Database (EM-DAT), a global database on natural and technological disasters, 1900 – Present
Droughts, epidemics, extreme cold temperatures, extreme hot temperatures, floods, storms and wildfires
Other controls from a variety of sources: World Development Indicators, Quality of Government
Econometric Specifications: Onset and Incidence
Panel logit specification Random effects logit Conditional (Fixed Effects) Logit
Significant loss of observations Fixed-Effects Linear Probability Model
Econometric Specification: Onset• Onset
• Disasters are: droughts, epidemics, extreme cold temperatures, extreme hot temperatures, floods, storms and wildfires
• Occurrence of civil war in the previous year, income per capita lagged one year, log(population density), log(percent of country’s terrain classified as “mountainous”), states with noncontiguous territories, oil-producing country, newly formed state, Polity IV, anocracy
itit XDisasterOnsetCivil_War_ :O1 Model it10it
ittit
s
XDisasterOnsetCivil_War_ :O8 Model3
0s-it0it
Results
Since the complete set of results is so voluminous, I will focus on just the key estimated coefficients For each 7 disaster types (and the joint
model) there are 8 regressions, and 3 types of specifications, for a total of 192 regressions
Only the significant coefficients on the disaster variables are summarized in these tables
Individual Disaster Events Regression Results: Onset
Variables Significant Coefficients Models Significant Coefficients ModelsDroughtt-1 0.589* O3 -- --Extreme Coldt 1.226** to 1.438*** O1,O2,O3,O4 1.209*** to 1.381*** O5,O6,O7,O8Extreme Heatt-1 1.098* to 1.427** O2,O3,O4 1.273* to 1.581** O6,O8Extreme Heatt-2 1.091* O3 -- --Extreme Heatt-3 1.102* O4 1.135* O8Epidemict 0.299* to 0.380** O1,O2,O3,O4 0.346* to 0.379** O5,O6,O7,O8Stormt-2 0.235* to 0.316** O3,O4 0.353* O8Stormt-3 -- -- -0.511* O8Wildfiret 1.125** to 1.247*** O1,O2,O3,O4 1.133** to 1.234** O5,O6,O7,O8Control VariablesTime Fixed EffectsNote: Summary of selected coefficients from Appendix A Tables A1 through A7. Only significant coefficients are presented. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Table 7. Determinants of Civil War Onset : Significant Coefficients from Individual Event Panel Logit Models, 1945-1999 (n=6278)
Yes YesNo Yes
Individual Disaster Events Regression Results: Onset
Variables Significant Coefficients Models Significant Coefficients ModelsDroughtt-1 0.589* O3 -- --Extreme Coldt 1.226** to 1.438*** O1,O2,O3,O4 1.209*** to 1.381*** O5,O6,O7,O8Extreme Heatt-1 1.098* to 1.427** O2,O3,O4 1.273* to 1.581** O6,O8Extreme Heatt-2 1.091* O3 -- --Extreme Heatt-3 1.102* O4 1.135* O8Epidemict 0.299* to 0.380** O1,O2,O3,O4 0.346* to 0.379** O5,O6,O7,O8Stormt-2 0.235* to 0.316** O3,O4 0.353* O8Stormt-3 -- -- -0.511* O8Wildfiret 1.125** to 1.247*** O1,O2,O3,O4 1.133** to 1.234** O5,O6,O7,O8Control VariablesTime Fixed EffectsNote: Summary of selected coefficients from Appendix A Tables A1 through A7. Only significant coefficients are presented. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Table 7. Determinants of Civil War Onset : Significant Coefficients from Individual Event Panel Logit Models, 1945-1999 (n=6278)
Yes YesNo Yes
Individual Disaster Events Regression Results: Onset
Variables Significant Coefficients Models Significant Coefficients ModelsDroughtt-1 0.589* O3 -- --Extreme Coldt 1.226** to 1.438*** O1,O2,O3,O4 1.209*** to 1.381*** O5,O6,O7,O8Extreme Heatt-1 1.098* to 1.427** O2,O3,O4 1.273* to 1.581** O6,O8Extreme Heatt-2 1.091* O3 -- --Extreme Heatt-3 1.102* O4 1.135* O8Epidemict 0.299* to 0.380** O1,O2,O3,O4 0.346* to 0.379** O5,O6,O7,O8Stormt-2 0.235* to 0.316** O3,O4 0.353* O8Stormt-3 -- -- -0.511* O8Wildfiret 1.125** to 1.247*** O1,O2,O3,O4 1.133** to 1.234** O5,O6,O7,O8Control VariablesTime Fixed EffectsNote: Summary of selected coefficients from Appendix A Tables A1 through A7. Only significant coefficients are presented. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Table 7. Determinants of Civil War Onset : Significant Coefficients from Individual Event Panel Logit Models, 1945-1999 (n=6278)
Yes YesNo Yes
Many Disaster Events Regression Results: Onset
Variables Significant Coefficients Models Significant Coefficients ModelsDroughtt-2 -- -- -0.862* O7Extreme Coldt 0.913* to 1.205*** O1,O2,O4 0.949* to 1.226*** O5,O6,O8Extreme Heatt-1 -- -- 1.400* O8Epidemict 0.300* O1 0.345* to 0.391* O5,O6,O7,O8Stormt-2 0.358** O4 0.417** O8Stormt-3 -0.478* O4 -0.624** O8Control VariablesTime Fixed Effects
Table 8. Determinants of Civil War Onset : Significant Coefficients from All Events Panel Logit Models, 1945-1999 (n=6278)
Yes YesNo Yes
Note: Summary of selected coefficients from Appendix A Table A8. Only significant coefficients are presented. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Econometric Specification: Incidence• Incidence
• Disasters are: droughts, epidemics, extreme cold temperatures, extreme hot temperatures, floods, storms and wildfires
• Income per capita lagged one year, log(population density), log(percent of country’s terrain classified as “mountainous”), states with noncontiguous territories, oil-producing country, newly formed state, Polity IV, anocracy
itit XDisastersin_ProgresCivil_War_:P1 Model it10it
ittit
s
XDisastersin_ProgresCivil_War_:P8 Model3
0s-it0it
Individual Disaster Events Regression Results: Incidence
Variables Significant Coefficients Models Significant Coefficients ModelsExtreme Coldt 0.94** to 1.159*** P1,P2,P3,P4 -- --Extreme Heatt-1 1.008* to 1.029* P2,P3,P4 1.003* to 1.053* P6,P7,P8Extreme Heatt-2 1.526*** to 1.543*** P3,P4 1.511*** to 1.564*** P7,P8Extreme Heatt-3 1.265** P4 1.193*** P8Floodt 0.152* to 0.218*** P1,P2,P3 -- --Floodt-1 0.139* to 0.169** P2,P3 -- --Floodt-3 0.164* P4 -- --Stormt 0.142** P1 -- --Control VariablesTime Fixed Effects
Note: Summary of selected coefficients from Appendix D Tables D1 through D7. Only significant coefficients are presented. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Table 9. Determinants of Civil War Incidence : Significant Coefficients from Individual Event Panel Logit Models, 1945-1999 (n=6278)
Yes YesNo Yes
Many Disaster Events Regression Results: Onset
Variables Significant Coefficients Models Significant Coefficients ModelsExtreme Coldt 0.797* to 0.951** P1,P2,P3,P4 -- --Extreme Heatt-1 -- -- 1.022* to 1.06* P6,P7,P8Extreme Heatt-2 1.489** to 1.501** P3,P4 1.601*** to 1.627*** P7,P8Extreme Heatt-3 1.181* P4 1.258** P8Floodt 0.152* to 0.218*** P1,P2,P3 -- --Floodt-1 0.165** P1 -- --Control VariablesTime Fixed Effects No YesNote: Summary of selected coefficients from Appendix D Table D8. Only significant coefficients are presented. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Table 10. Determinants of Civil War Incidence : Significant Coefficients from All Events Panel Logit Models, 1945-1999 (n=6278)
Yes Yes
Econometric Specification: Duration
• Duration– I allow climate-change-related disasters to vary
over the duration of a war– Specifications
– Cox proportional hazards model– Exponential– Weibull– Gompertz– a discrete time proportional hazards model (Prentice-
Gloeckler, 1978) – Logistic regression models
Econometric Specification: Variables
Duration Disasters: droughts, epidemics, extreme
cold temperatures, extreme hot temperatures, floods, storms and wildfires
Controls: Coups, anti-colonial wars, Eastern Europe, “Sons of soil”, contraband production and trade, income, democracy,
Individual Disaster Events Regression Results: Duration
Models Droughtt
Cox -0.117*Exponential -1.377**Weibull -1.485**
Gompertz -1.415**
Discrete Time Proportional Hazards -1.400**Logit -1.460**
Table 11. Determinants of Civil War Duration Controlling for Frequency of Drought Events,
1945-1999 (n=1102)
Note: Summary of selected coefficients from Appendix G Tables G1 through G7. Only significant coefficients are presented. All six models include a full set of controls. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Many Disaster Events Regression Results: Duration
Models Droughtt
Cox -0.128**Exponential -1.377**Weibull -1.488**Gompertz -1.412**Discrete Time Proportional Hazards -1.418**Logit -1.462**
Table 12. Determinants of Civil War Duration Controlling for Frequency of All
Disaster Events, 1945-1999 (n=1102)
Note: Summary of selected coefficients from Appendix G Table G8. Only significant coefficients are presented. All six models include a full set of controls. Standard errors in parentheses, *** p<0.01, ** p<0.05, * p<0.1.
Conclusion
First evidence on the impact of individual climate-change-related natural disasters on various measures of civil war Extreme cold events and epidemic outbreaks
increase the probability of civil war onset Previous years’ extreme heat events increase the
probability of civil occurring Drought events prolong civil war duration
Results can inform policy makers as they contemplate policies to mitigate and adapt to climate change