The drought, the worst in modern record-keeping, destroyed agriculture in the breadbasket region of northern Syria, driving dispossessed farmers to cities, where poverty, government mismanagement and other factors created unrest that exploded in spring 2011. The conflict has since evolved into a complex multinational war that may have killed 200,000 people and displaced many more.
There are claims that extreme weather, including high temperatures and droughts, increases the chances of violence, from individual attacks to full-scale wars. Some believe that man-made global warming will heighten future conflicts, or argue that it may already be doing. The new paper, combining climate, social and economic data, is perhaps the first to estimate the possible effects of these issues in relation to a current war.
2006-2010, drought (brown areas) across Turkey, Syria and Iraq. Syria was especially vulnerable to its effects, according to a new paper. Credit: NASA
The recent drought affected the so-called Fertile Crescent, spanning parts of Turkey and much of Syria and Iraq, where agriculture and animal herding are believed to have started some 12,000 years ago. The region has always seen natural weather swings. But using existing studies and their own research, the authors showed that since 1900, the area has undergone warming of 1 to 1.2 degrees Centigrade (about 2 degrees Fahrenheit), and about a 10 percent reduction in wet-season precipitation.
They saw that the trend matches neatly with models of human-influenced global warming and so a correlation-causation paper was born.
Global warming has had two effects, they believe. First, it appears to have indirectly weakened wind patterns that bring rain-laden air from the Mediterranean, reducing precipitation during the usual November-April wet season. Second, higher temperatures have increased evaporation of moisture from soils during the usually hot summers, giving any dry year a one-two punch. The region saw substantial droughts in the 1950s, 1980s and 1990s. However, 2006-10 was easily the worst and longest since reliable record-keeping began. The researchers concluded that an episode of this severity and length would have been unlikely without the long-term changes.
The study's authors say Syria was made especially vulnerable by other factors, including sheer population growth--from 4 million in the 1950s to 22 million in recent years. Also, the ruling al-Assad family encouraged water-intensive export crops like cotton. Illegal drilling of irrigation wells dramatically depleted groundwater that might have provided reserves during dry years, said coauthor Shahrzad Mohtadi, a graduate student at Columbia's School of International and Public Affairs who did the economic and social components of the research.
The drought's effects were immediate. Agricultural production, typically a quarter of the country's gross domestic product, plummeted by a third. In the hard-hit northeast, livestock herds were practically all obliterated; cereal prices doubled; and nutrition-related diseases among children saw dramatic increases. As many as 1.5 million people fled from the countryside to the peripheries of cities that were already strained by influxes of refugees from the ongoing war in next-door Iraq. In these chaotic instant suburbs, the Assad regime did little to help people with employment or services, said Mohtadi. It was largely in these areas that the uprising began.
"Rapid demographic change encourages instability," say the authors. "Whether it was a primary or substantial factor is impossible to know, but drought can lead to devastating consequences when coupled with preexisting acute vulnerability."
"We're not saying the drought caused the war," said co-author Richard Seager, a climate scientist at Columbia University, "We're saying that added to all the other stressors, it helped kick things over the threshold into open conflict. And a drought of that severity was made much more likely by the ongoing human-driven drying of that region."
Citation: Colin P. Kelley, Shahrzad Mohtadi, Mark A. Cane, Richard Seager, and Yochanan Kushnir
Climate change in the Fertile Crescent and implications of the recent Syrian drought
PNAS 2015 ; published ahead of print March 2, 2015, doi:10.1073/pnas.1421533112
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