Climate: El Niños May Inflame Civil Unrest

One in five major civil conflicts since 1950 may be linked to climate extremes associated with El Niños — periods of warming lasting a year or longer in surface waters of the central equatorial Pacific, a new study finds.

I'm one of those people who would be generally skeptical about correlating things to climate, says statistician Andrew Solow of the Woods Hole Oceanographic Institution in Massachusetts. But the new report's finding makes sense, he says: In poor countries where the economy is closely linked to agriculture — and therefore the weather — poor harvests and diminishing food supplies can leave large numbers of people available to engage in civil uprisings.

Hsiang and his colleagues analyzed 234 civil conflicts that broke out within 175 nations between 1950 and 2004. In any given year, the probability that a new conflict would erupt among the 90 or so nations whose climates can be heavily affected by El Niño events was 4.1%. That's twice the conflict rate in countries largely immune to El Niño effects, Hsiang's group reports in the Aug. 25 Nature.

This disparity in violence rates is huge, Hsiang says: It's comparable to differences that others have reported between populations where annual incomes were $1,000 per capita versus $10,000.

For more, see EL NIñOS May Inflame Civil Unrest by Janet Raloff, August 24, 2011 at ScienceNews.