Before Syria devolved into civil war, that country experienced its worst drought on record. The consequences of this disaster included massive crop failures, rising food prices, unemployment, and a mass migration to urban areas. In a new study published in the Proceedings of the National Academy of Sciences, researchers suggest that the drought and its ensuing chaos helped spark the Syrian uprising. They go on to make the case that climate change was responsible for the severity of that drought. Colin P. Kelley, a climatologist at the University of California, Santa Barbara, was the study’s lead author. In an interview with Yale Environment 360, Kelley explains that long-term precipitation and soil temperature trends in Syria and the rest of the region known as the Fertile Crescent correlate well with climate change models, demonstrating, he says, that the record-setting drought can’t be attributed to natural variability.
Yale Environment 360: The multi-year drought in Syria that began in 2006 led to, among other things, a massive migration of farm families to urban areas and a steep rise in food prices. What were the societal effects of that upheaval?
Colin Kelley: Well, you had the drought and its severity, and it came on the heels of another severe drought in the 1990s. But in addition to that, Syria was highly vulnerable even before the drought, meaning that it had this very strong reliance on wheat production and on year-to-year rainfall variability, but also very strong reliance on groundwater for irrigation. And the groundwater had been going steadily down, partially due to the dramatic rise in population in recent decades. So there was basically a reduction in supply of water and an increase in the demand for water. And when the severe drought happened, there was an agricultural collapse in the northeastern breadbasket region. It was so severe and different than anything in the past that the farmers basically picked up their families and abandoned their villages in the northeast and went to the cities in Syria’s west to try and survive.
These up to a million-and-a half internally displaced people from the rural areas to the urban areas came shortly after the influx of as many as a million-and-a-half Iraqi refugees from when the U.S. went into Iraq [in the preceding years]. So there was a tremendous population shock, an increase in population in these urban areas in Syria’s west — a 50-percent increase in population in those cities from 2002 to 2010. That’s a dramatic rise in population in a very short period of time, and it basically occurred right before the uprising.
The drought was so severe ‘farmers basically picked up their families and abandoned their villages.’
e360: When this mass migration occurred and then there was a steep rise in food prices, this led to various levels of chaos, including unemployment and overcrowding. That’s how you are making this link to the uprising, correct?
Kelley: Yes. There were so many people and they were trying to survive, and there were not adequate resources for all of these newcomers. There was also an increase in crime and in urban slums that were on the peripheries of these cities. And so there was a tremendous amount of unrest and desire for resources directly before the beginning of the uprising. Now it’s hard to say, and we can’t even attempt to say, that any one particular or any combination of these things necessarily precipitated the uprising. There are a host of factors that play into something like that. Syria was the last of the Arab Spring uprising countries. I think many of the people [in Syria] were aware of the uprisings that had taken place in other countries.
e360: In your paper, you and your colleagues attempted to tease out the climate change signal in this drought from natural variation by looking at a couple of variables. Let’s start with the change in winter rainfall, winter being the wet season in this region. What did you find with that?
Kelley: There was a very clear significant downward trend [in precipitation] over the last 80 years, and really over the last 110 years. We had some confidence that this trend was very significant, and that it was real. What we tried to do was to say, “In the absence of this trend, how likely is it that you would have a drought of this severity?” We decided that it was two to three times more likely that a drought of this severity would occur when you include the long-term trend as opposed to when you don’t. And we attempted to corroborate that, using global climate models. Fortunately, this is a region where the global climate models had done a pretty good job of simulating the observed climate over the 20th century. And so we took the models that appeared in the most recent IPCC [Intergovernmental Panel on Climate Change] report, and we compared them to the experiments. And the models actually agreed quite well with the analysis that we observed. That gave us some confidence to say that these continued projections by the models of the 21st century that suggest that this region will continue to get dryer and hotter are reliable.
‘This is a region where the models have done a pretty good job of simulating the observed climate.’
e360: You also looked at the change in surface temperature, which influences soil moisture reserves. What did you find there?
Kelley: In particular, over the last 20 or 30 years, you can see the long-term trend is that the temperatures have really risen. In this region, there’s winter when they get all of their rainfall, and then there’s summer when most of the evaporation occurs. But as the evaporation has enhanced essentially during summer, the reserves of some moisture left over from the summer are less and less. There’s been some literature that suggests that these crops they’re growing in the winter, including the wheat in Syria, are somewhat dependent on these reserves of soil moisture. So it’s kind of a double-whammy.
In addition, with the tremendous population increase, the demand for water has been going up dramatically as the supply for water has been going down. And in Syria the farmers not only rely on the year-to-year precipitation, but they also rely strongly on groundwater and wells to be able to provide irrigation for these crops. So as the groundwater has been going down, they get less precipitation. It’s been steadily becoming a larger problem.
e360: In your paper, you and your colleagues write, “Natural variability on timescales of centuries or longer cannot be entirely ruled out for this region.” In your mind, how do you sum up your certainty that the thread going from climate change to this severe drought holds?
‘The preponderance of evidence suggests very strongly that these trends can by explained by global warming.’
Kelley: I would say that the preponderance of the evidence suggests very strongly that these long-term trends can be explained by global warming or human-induced warming, whereas there’s very little evidence to suggest that these long-term trends over the last century are related to natural variability. Nothing that we know of, anyway.
e360: You mention that this latest drought in Syria came on the heels of a severe drought in the 90s, and you write that the region never fully recovered from that drought before it was hit with the last one. Given that, what do you foresee in terms of the frequency of drought in this region and the accompanying societal effects?
Kelley: Well, it’s difficult to say anything with any kind of high statistical significance. But empirically, of the multiyear droughts that occurred in Syria or the Fertile Crescent during the 20th century, one occurred in the 1950s, there was another in the 80s and 90s, and then there was this most recent drought. So three of the four severe multiyear droughts occurred within the last 25 to 30 years, which suggests again that the long-term trend has some influence there and that these kinds of droughts have become more frequent recently.
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e360: What other regions of the world might you be studying in a similar manner? Where else do you believe societal upheaval might be exacerbated by climate change in the near term?
Kelley: Well, the project that I’m working on is Yemen. Now Yemen is a very different country than Syria in terms of its water resources. The six-month winter season is when all of the rain falls in Syria, whereas in Yemen, which is much more of a tropical country, there are two distinct rainy seasons — one in the spring, and one in the monsoon season in the summer. And so far, research indicates that there’s been a steady drying of the spring rains in Yemen over the last 35 years. Now there’s less data available in this region prior to the satellite era. So it’s difficult to say whether this is a much longer trend, or whether it’s just been a recent trend. But certainly Yemen is another example of an Arab Spring country that is strongly reliant on the rain that falls there, particularly in the west where most of the population and the cities are. You have this strong dependence on rainfall, but also on the groundwater. So there are a lot of analogies to be drawn between these two countries.