From 2007 to 2010, Syria suffered a debilitating drought that brought crop failure and livestock mortality to as much as 60% of the country and displaced up to 1.5 million people. A year later, Syria descended into chaos. A repressive regime and the spread of the 2011 Arab Spring were the overt drivers of the conflict, but some scientists argue that drought played a powerful role. Now, a new study finds that human-induced climate change has increased the likelihood of such a severe drought occurring in the region two- to threefold. The researchers examined a century of observed trends in precipitation, temperature, and sea-level pressure in the Eastern Mediterranean and noted a long-term warming trend and decreased winter rainfall in the second half of the 20th century. That drying trend is separate from the climate’s natural (not human-induced) variability, they report online today in the Proceedings of the National Academy of Sciences. When increased greenhouse gas emissions, particularly of carbon dioxide, are included in models, they more than double the likelihood of a severe, 3-year drought in the Fertile Crescent, they found. That agrees with the conclusion of a 2011 National Oceanic and Atmospheric Administration study that linked increasing incidence of droughts in the Mediterranean region over the last 20 years to human-induced climate change. The link to conflicts is more uncertain, but previous teams have found that fluctuations in climate have been a statistically significant driver of social disturbances over centuries of human history, including war, famine, and migration.