Extreme Weather, Extreme Violence

“…researchers are now quantifying the causal relationship between extreme climate and human conflict. Whether their focus is on small-scale interpersonal aggression or large-scale political instability, low-income or high-income societies, the year 10,000 B.C. or the present day, the overall conclusion is the same: episodes of extreme climate make people more violent toward one another.”

… We found that higher temperatures and extreme rainfall led to large increases in conflict: for each one standard deviation change in climate toward warmer temperatures or more extreme rainfall, the median effect was a 14 percent increase in conflict between groups, and a 4 percent increase in conflict between individuals.

The studies in our analysis covered all major regions of the world and showed remarkably similar patterns across a wide range of settings. For example, they documented that spikes in temperature increased violent crime in the United States and Australia, that years of low rainfall increased domestic violence and ethnic conflict in South Asia, that extreme rainfall events increased land invasions in Brazil and that warmer temperatures increased civil conflict throughout the tropics. These studies also documented the role that climate played in the collapse of many of human history’s iconic civilizations: the Akkadian empire in Syria around 2000 B.C., the Maya in Mexico in the ninth century A.D. and Angkor Wat in the 1400s.

Weather and Violence