Many experts have predicted that as the impacts of climate change begin to take hold that the world will see an increase in refugees and violent conflict.

As drought, rising sea levels and violent storms destroy crops, reduce water availability and available cropland people will flee in search of resources and fight over what remains.

According to a new study published in the Proceedings of the National Academy of Sciences the world may have already seen a significant example of this.

From 2006-2010 the most serious drought on record ravaged the “breadbasket region” of northern Syria. As crops failed year after year, farmers were driven into cities where they were met with poverty and a lack of government assistance.

In 2011, Syria exploded into a civil war that has killed at least 220,000 people and has driven more refugees across Syria’s borders in every direction .

“We’re not saying the 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,” said Richard Seager in a statement.

Seager is a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory who coauthored the study.

The agricultural region of Northern Syria is in the so-called “Fertile Crescent” which includes parts of Syria, Turkey and Iraq. It is the part of the world where agriculture is believed to have first taken hold 12,000 years ago.

The region has been prone to periodic droughts, including one in 4,200 that is believed to have caused the fall of the Akkadian Empire. The four year drought that began in 2006 however was particularly severe and, when combined with other factors, had a destabilizing effect on the region.

The authors of the study showered that since 1900, the Fertile Crescent region has warmed by about two degrees Fahrenheit and has seen a 10 percent reduction in precipitation during the wet season. That trend closely matches the models of human-influenced global warming and cannot, according to the authors, be attributed to natural weather variations.

The researchers state that global warming has had two effects. It has weakened normal wind patterns and increased temperatures. The wind normally brings moist air and rainfall from the Mediterranean during the November to April rainy season. The increased temperatures have, at the same time, caused increased evaporation of the remaining moisture during the hot summers.

This is supported by other research, including a study by the U.S. National Oceanic and Atmospheric Administration (NOAA) that shows a long-term drying trend across the Mediterranean. The Intergovernmental Panel on Climate Change has also predicted an increase in conflict in the coming decades as agricultural lands dry out.

The reports authors do not believe that the drought, by itself, was responsible for the unrest in Syria. The country was already ripe for conflict and did little to prevent it. Among the issues plaguing the region were rapid population growth, from 4 million in the 1950s to more than 22 million when the conflict begun, government programs to encourage the growth of water-intensive crops like cotton and illegal drilling of wells for irrigation that depleted groundwater.

When the drought came and dragged on, the countries gross domestic product (GDP) plummeted, food prices increased, and nutrition-related diseases increased. The Assad government did nothing to provide services or employment for the destitute farmers. An estimated 1.5 million people fled the countryside into make-shift suburbs around large cities and it was in these overcrowded refugee settlements that the uprising began.

“Rapid demographic change encourages instability. 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,” said the authors.

The research could provide a useful case study. The true impacts of climate change have only begun to take hold in much of the world and it is likely that the Syrian situation will replay itself elsewhere.