The Guardian notes:
Cyclical climatic changes double the risk of civil wars, with analysis showing that 50 of 250 conflicts between 1950 and 2004 were triggered by the El Niño cycle, according to scientists.
Researchers connected the climate phenomenon known as El Niño, which brings hot and dry conditions to tropical nations and cuts food production, to outbreaks of violence in countries from southern Sudan to Indonesia and Peru.
Solomon Hsiang, who led the research at Columbia University, New York, said: "We can speculate that a long-ago Egyptian dynasty was overthrown during a drought. This study shows a systematic pattern of global climate affecting conflict right now. We are still dependent on climate to a very large extent."
Hsiang said that pre-emptive action could prevent bloodshed because El Niño events could be predicted up to two years ahead. "We hope our study may help reduce humanitarian suffering."
The scientists are beginning work to discover the factors involved in the climate-conflict link. Food is likely to be key as crop yields and incomes from agriculture are known to fall heavily in El Niño years. "When crops fail, people may take up a gun to make a living," said Hsiang.
Other factors could include rises in unemployment and natural disasters, such as hurricanes. "Also, previous work has shown that when people get warm and uncomfortable, they are more prone to fight," said Cane.
Marshall Burke, an economist at the University of California, Berkeley, said the research gave very convincing evidence of a connection.Andrew Solow, an environmental statistician, at the Woods Hole Oceanographic Institution, said: "Careful statistical analyses such as this one, which relate complex human behaviour to environmental factors, can be invaluable."
And - in keeping with my recent slew of reports on the sun's effect on the Earth - solar activity may play a substantial role in El Nino conditions.