This article has been cross-posted from Carbon Brief

This month will see the civil war in Syria reach an inauspicious fourth birthday. Since the uprising in 2011, over  220,000 people have been killed and almost half the Syrian population have fled their homes.

Evidence suggests the conflict was triggered by a complex mix of  social, political, economic and  environmental factors. But new research finds that human-caused climate change could also have had an influence.

The study, published in the Proceedings of the National Academy of Sciences, suggests a severe drought that began in 2006 was a catalyst for the conflict, and that climate change has made such droughts in the region more than twice as likely.

Syrian conflict

On 15th March 2011, Syrian security services opened fire on pro-democracy protesters in the southern city of Dara’a, killing several people. The unrest that followed spread throughout the country over the ensuing months, and by  February 2012, Syria had descended into civil war.

A  study published last year found that a multi-year drought contributed to food shortages, urban migration, and unemployment in the run up to the conflict.

Now the new study says the drought had a catalytic effect on the unrest in Syria, and human-caused climate change has made the chances of such a severe drought between two and three times more likely.

Prof Richard Seager, a climate scientist at Columbia University and co-author on the new study, explains:

“We’re not saying drought caused the war. 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.”

Multi-year drought

Syria sits in a band of relatively moist and productive land in the Middle East, known as the Fertile Crescent. But between 2006 and 2010, the region was hit by the worst multiyear drought  since 1940.

Syria gets almost all of its rain during its six-month winter, from November to April. In 2007-08, winter rainfall across Syria  fell by a third, with some areas receiving no rain at all. The winter was the driest in the observed record, the researchers say.

The decreasing rainfall (shown in the top graph below) combined with rising temperatures (second graph) resulted in a decline in soil moisture (third graph), the researchers say. This had dramatic consequences for Syrian agriculture.

Long-term climate trends and population history for Syria. Graphs show A) six-month winter (November to April) rainfall, B) annual temperature, C) annual soil moisture, and D) total population. Red lines show annual trend, grey shading shows where data is taken from only a small number of stations, and brown shading indicates multiyear droughts. Source: Kelley et al. (2015)

Impacts of the drought

Syria’s economy relies heavily on agriculture, which in turn relies heavily on water. One study estimates that around 90 per cent of Syria’s freshwater is used for agriculture.

The combination of the 2006-2010 drought and widespread overuse of groundwater in previous decades meant crop yields plummeted across the country, the new study says. In 2007-08, harvests of staple crops such as barley and wheat fell by 67 per cent and 47 per cent, respectively, compared to the previous year.

The shortfall meant Syria had to import large quantities of cereals, the researchers say, causing food prices to more than double. Decisions by the Syrian government to withdraw food and fuel subsidies made food even less affordable.

As the drought continued, farmers and their families abandoned their land and headed to urban areas for work. Around 1.5 million people migrated to Syrian cities during the drought, adding to the high population growth and recent arrival of 1.2 to 1.5 million Iraqi refugees.

The growing urban populations resulted in overcrowding, unemployment and crime, but the worsening situation was neglected by the Syrian government, the study says. This growing unrest, the researchers say, was the trigger for the uprising.

Timeline of events leading up to the civil uprising in March 2011, along with a graph showing the net migration of displaced Syrians and Iraqi refugees into urban areas (in millions) since 2005. Source: Kelley et al. (2015)

Conflicting views

It’s impossible to quantify the importance of each individual factor in the conflict, lead author Dr Colin Kelley, a researcher at the University of California, tells Carbon Brief. But, he says:

“The long term trends made the recent drought more severe and there is a very clear sequence of events leading to the uprising that was initiated by this most severe drought.”

In its recent synthesis report, the Intergovernmental Panel on Climate Change (IPCC) says there is “medium confidence” that climate change can indirectly increase risks of violent conflict by amplifying poverty and economic shocks.

Dr Peter Gleick, an expert on water and conflict at the Pacific Institute, says the evidence for the impact of climate change on security is mounting:

“The war in Syria has many causes, from ancient enmities, religious and ideological disputes, economic and social pressures, and political tensions. But there is growing evidence that pressures on water resources associated with poor management, increasing populations, and human-caused climate changes are now influencing regional security in new and disturbing ways.”

But not everyone is convinced. Dr Francesca de Châtel, an academic specialising in water issues in the Arab world, says that while the drought may have made an existing humanitarian crisis worse, it didn’t drive Syrians to protest:

“The uprising has more to do with the government’s failure to respond to the drought and provide aid to affected communities, and the discontent this caused, than with the drought itself. The drought obviously worsened this situation, but I don’t think the uprising would have started in Syria if other countries in the region hadn’t set the example.”

Alex Randall, project manager of the Climate Change and Migration Coalition, says that the link between climate change and conflict is still fairly weak, and that it shouldn’t shift the responsibility of the war away from political or diplomatic failures:

“There is a risk that research like this can be misused by people wishing to justify or play down atrocities. This is clearly not the intent of the researchers. But it’s important to be alert for people abusing research like this to downplay the role of political actors who actively chose a course of violent conflict.”

Peace and security

The Syrian civil war clearly has a very specific set of circumstances that surrounds it. But if climate change is contributing in some way, these links need further research, says Gleick:

“We can no longer ignore the influence of climate change on a wide range of issues of societal concern, including peace and security.”

Glada Lahn, a senior research fellow at thinktank Chatham House, says the water issues often affect more than one country at a time, making international cooperation even more important:

“Syria is over 70 per cent dependent on water originating outside of its borders – primarily through the Euphrates. Governments have missed many opportunities to cooperate over water that might have allowed a more effective response to the drought.”

Prof Neil Adger, lead author of the Human Security chapter of the latest IPCC report, says the research prompts important questions for the future:

“The key question then is how this region can manage the step change towards a drier climate? How can countries avoid food insecurity and even displacement of rural populations given its consequences for human security? Other countries in the Fertile Crescent have not had such population displacement – let’s learn from those cases too.”

Kelley, C.P. et al. (2015) Climate change in the Fertile Crescent and implications of the recent Syrian drought, Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1421533112

Photo: Dana Bozzi via Shutterstock