Notorious El Nino Doubles Civil Wars, Scientists Say

The El Nino climate cycle brings not only high temperatures and dry weather, but also more chances of civil wars, a new study claims.

Between 1950 and 2004, the risk of civil wars doubled in 90 tropical countries when hit by El Nino, is the warm phase of the El Niño-Southern Oscillation, or ENSO, a periodic warming and cooling of the tropical Pacific Ocean.

While its partner La Nina is a cool, rainy period, El Nino brings high temperature and more scarce rainfall every three to seven years, impacting weather patterns across much of Africa, the Mideast, India, southeast Asia, Australia, and the Americas, which holds half the world's population. 

Interacting with other factors including wind and temperature cycles over the other oceans, El Nino can vary dramatically in power and length. At its most intense, it brings scorching heat and multi-year droughts. 

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In the study published in Wednesday's Nature, scientists from Princeton University and Columbia University's Earth Institute used statistics to link global weather observations and outbreaks of violence. 

The scientists correlated ENSO from 1950 to 2004 with onsets of civil conflicts that killed more than 25 people in a given year. The data included 175 countries and 234 conflicts, with over half of which each caused more than 1,000 battle-related deaths.

The findings suggest that the arrival of El Nino doubled the risk of civil conflict across 90 affected tropical countries, and may help account for a fifth of worldwide conflicts over the past half-century. 

Remarkable links were found between El Nino patterns and civil unrest in Peru in 1982 and Sudan in 1963.

Further, a strong link between violence and El Nino were also found in El Salvador, the Philippines and Uganda in 1972; Angola, Haiti and Myanmar in 1991, and Congo, Eritrea, Indonesia and Rwanda in 1997.

"This is the first major evidence that the global climate is a major factor in organized violence around the world," says Solomon M. Hsiang, the study's lead author, a graduate of the Earth Institute's Ph.D. in sustainable development.

While the study does not blame specific wars on El Nino, it confirms many scientists' speculation over the strong link between climate-conflict.