Citation

Roche KR, Müller-Itten M, Dralle DN, Bolster D, Müller MF. Proc. Natl. Acad. Sci. U. S. A. 2020; ePub(ePub): ePub.

Affiliation

Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556.

Copyright

(Copyright © 2020, National Academy of Sciences)

DOI

10.1073/pnas.1914829117

PMID

31932433

Abstract

A growing empirical literature associates climate anomalies with increased risk of violent conflict. This association has been portrayed as a bellwether of future societal instability as the frequency and intensity of extreme weather events are predicted to increase. This paper investigates the theoretical foundation of this claim. A seminal microeconomic model of opportunity costs-a mechanism often thought to drive climate-conflict relationships-is extended by considering realistic changes in the distribution of climate-dependent agricultural income.

RESULTS advise caution in using empirical associations between short-run climate anomalies and conflicts to predict the effect of sustained shifts in climate regimes: Although war occurs in bad years, conflict may decrease if agents expect more frequent bad years. Theory suggests a nonmonotonic relation between climate variability and conflict that emerges as agents adapt and adjust their behavior to the new income distribution. We identify 3 measurable statistics of the income distribution that are each unambiguously associated with conflict likelihood. Jointly, these statistics offer a unique signature to distinguish opportunity costs from competing mechanisms that may relate climate anomalies to conflict.

Language: en

Keywords

agriculture; income shock; microeconomic theory; rainfall; violence