02 August, 2013

Climate and conflict may be causally related

Sergio Abranches

US scientists report a remarkable convergence of results from rigorous quantitative studies showing that climactic changes are strongly correlated with a rise in interpersonal violence (assaults, rapes and murders), as well as group conflicts and war.

Marshall Burke, from the University of California, Berkeley, told BBC News that : “This is a relationship we observe across time and across all major continents around the world. The relationship we find between these climate variables and conflict outcomes are often very large.” But, he cautioned: “We want to be careful, you don’t want to attribute any single event to climate in particular, but there are some really interesting results.”

A correlation does not  really points to a causal relation. It only says there is a relationship. The direct cause of violence could be, for instance, food or water shortage caused by climate extremes. Burke also told BBC there could be a physiological basis as well, because some studies suggest that heat causes people to be prone to aggression.

On the paper published by Science, the authors say that a rapidly growing body of research examines whether human conflict can be affected by climatic changes. Drawing from archaeology, criminology, economics, geography, history, political science, and psychology, they have assembled and analyzed the 60 most rigorous quantitative studies. Their review documents, for the first time, they argue, a remarkable convergence of results, “showing strong causal evidence linking climatic events to human conflict across a range of spatial and temporal scales and across all major regions of the world.”

The paper estimates that the magnitude of climate’s influence is substantial: for each 1 standard deviation change in climate toward warmer temperatures or more extreme rainfall, median estimates indicate that the frequency of interpersonal violence rises 4% and the frequency of intergroup conflict rises 14%. “Because locations throughout the inhabited world are expected to warm 2 to 4 standard deviations by 2050, amplified rates of human conflict could represent a large and critical impact of anthropogenic climate change.”

They estimate that a 2C (3.6F) rise in global temperature could see personal crimes increase by about 15%, and group conflicts rise by more than 50% in some regions.

Their assertion that they’ve found “strong causal evidence linking climatic events to human conflict” should be taken with a grain of salt. This kind of sociopolitical phenomena is very complex, and have several triggering causal factors, on different combinations: social, economic, physical, physiological, psychological, cultural. It is very likely a case of multivariate causation, where climatic extremes may have both a direct and an indirect causal impact on violent human and group behavior. The authors are right to say that a large avenue lies ahead to arrive at the hidden factors that would fully explain the correlation they have found.

Tags: , , ,