Last year, nearly 102,000 people were killed in armed conflicts across the world according to the Peace Research Institute Oslo. Many of them died in civil wars, and since 1946, two-thirds of civil wars have been fought between rival ethnic groups.
But climate-related problems, like crop failures, also play a role. Research published last year found that between 1980 and 2010, 23% of civil wars coincided with climate-related disasters in countries with deep ethnic divides. And worryingly global warming may make this kind of disaster more common.
Delving back into history, another study discovered that outbreaks of violence against Jews often seemed to be linked with economic shocks. The authors examined more than 1,360 pogroms or expulsions in more than 930 cities between 1100 and 1800, and plotted them against falls in temperature big enough to reduce crop yields.
They found that a fall of just one third of a degree increased the danger of a pogrom or an exclusion by half over the next five years. As we have seen recently, in times of economic difficulty or disappointment, it is very tempting to blame people who are different in some way.
For more on the link between global warming and war, see my posts of 21 September and 25 November, 2009.