Climate cycles influence human conflict

Climate change destabilizes natural ecosystems, but does it also instigate war?

A new study in the journal Nature sheds light on the hotly contested debate about whether climate variability plays a role in the onset of violence, especially in poor countries. The researchers led by Solomon Hsiang from Columbia University’s School of International and Public Affairs focused on natural global climate cycles.

They found that the arrival of El Niño, which raises temperatures and cuts rainfall in tropical countries, is associated with a doubling of the risk of civil war in 90 tropical countries. As such, El Niño may help account for about one-fifth of worldwide conflicts during the past 50 years.

Photo: Azani Manaf on Flickr

Historians and climatologists have long associated heat and droughts with the shaking and falling of past civilizations. Just think of Jared Diamond‘s bestseller: Collapse: How Societies Choose to Fail or Succeed. But the authors claim this is the first study to make the case for contemporary societies, using broad statistical methods that show an uptick in violence around the world during the three to seven year El Niño cycle.

From 1950 to 2004, the scientists tracked 234 conflicts in 175 countries. For nations whose weather is controlled by the El Niño-Southern Oscillation, or ENSO, the chance in any given year of a breakout in civil war was 3 percent. During an El Niño year, the chance doubled to 6 percent. Countries not impacted by ENSO remained at a 2 percent chance.

Weather alone does not start wars, said Mark Cane, a climate scientist at Lamont-Doherty Earth Observatory.

“No one should take this to say that climate is our fate. Rather, this is compelling evidence that it has a measurable influence on how much people fight overall,” Cane said in a press release. “It is not the only factor–you have to consider politics, economics, all kinds of other things.”

But El Niño may add tension to an already restless place. The weather pattern often brings scorching, multi-year droughts, which can increase competition over scarce resources. Some stable countries like wealthy Australia, have never seen a civil war. But in countries like Peru (1982), Sudan (1963, 1976 and 1983), and El Salvador, the Phillipines, and Uganda (1972), El Niño years were correlated with a fresh outbreak of violence that escalated into civil war.

The study raises questions about how countries will fare under climate change, which many scientists believe will intensify extreme weather events. The analogy is not perfect since El Niño is short term, while climate change runs in the long term. Still, the study shows how climate, and its impacts on the environment, is part of the background to the picture of how societies function, or rather how they don’t.