Historians have speculated for years thatglobal environmental changes caused some ancient wars to erupt, or evensocieties to collapse. Such connections may still exist—because new researchfinds that the risk of civil war in tropical countries increases during hot,dry El Nino years as opposed to cooler La Nina periods. The study is in the journal Nature.

 

Researchers used a database of global conflicts over the last six decades,which included clashes resulting in at least 25 deaths in battle. They comparedthose data to the three- to seven-year cycling of El Nino. And they found thatthe risk of conflict doubled during El Nino years—but only in tropicalcountries most affected by the climate cycle. El Nino may have played a role inspurring a fifth of the 234 conflicts studied.

 

This study can’t determine a cause. But the researchers say hot El Ninoconditions can diminish harvests, causing food shortages and sparkingconflicts. And since El Nino can be predicted up to two years in advance,governments and NGOs might be better able to plan for the possibility of acivil war.

 

Thanks for the minute. For ScientificAmerican’s 60-Second Science, I’m Christopher Intagliata.