The drought was the worst in the country in modern times, and in a study published Monday in Proceedings of the National Academy of Sciences, the scientists laid the blame for it on a century-long trend toward warmer and drier conditions in the Eastern Mediterranean, rather than on natural climate variability.
The researchers said this trend matched computer simulations of how the region responds to increases in greenhouse-gas emissions, and appeared to be due to two factors: a weakening of winds that bring moisture-laden air from the Mediterranean and hotter temperatures that cause more evaporation.
Colin P. Kelley, the lead author of the study, said he and his colleagues found that while Syria and the rest of the region known as the Fertile Crescent were normally subject to periodic dry periods, “a drought this severe was two to three times more likely” because of the increasing aridity in the region.
Some social scientists, policy makers and others have previously suggested that the drought played a role in the Syrian unrest, and the researchers addressed this as well, saying the drought “had a catalytic effect.” They cited studies that showed that the extreme dryness, combined with other factors, including misguided agricultural and water-use policies of the Syrian government, caused crop failures that led to the migration of as many as 1.5 million people from rural to urban areas. This in turn added to social stresses that eventually resulted in the uprising against President Bashar al-Assad in March 2011.To be sure, the refugees from drought would not have had to elicit the kind of response that they did from President Assad of Syria. So, drought is not the immediate cause of the conflict. But demographic change--in this case an unwelcome influx of rural people into urban areas--is something that societies must always deal with. As it turned out, the Syrian government did not deal well with it, and the result has been a vastly larger disaster than the drought itself.