Displaced Iraqis receive food at a refugee camp in Qayyarah, south of Mosul, on Oct. 29. (Bulent Kilic/AFP/Getty Images)

For a new U.S. administration facing global security challenges, the relationship between food security — what the World Bank defines as “access to enough food for an active, healthy life” — and armed conflict deserves serious consideration. As new research shows, even an abundance of food resources can cause conflict.

Recent studies theorize that in Syria, where an estimated 250,000 to 400,000 people have died since 2011, the drought that preceded the civil war played a significant role in fueling political tensions. Increases in food prices caused by drought were also a factor in the 2011 Arab Spring uprisings in Tunisia, Jordan, Yemen and Egypt.

The fact that prolonged food shortages can lead to drastic, violent behavior is becoming increasingly evident. The relationship between food and war is both complex and multidimensional, though.

The links between food scarcity and war

Warmer countries are more war-prone — that’s what researchers studying the relationships between environmental factors and civil war argue. As global temperatures increase, prolonged heat waves reduce crop yields. The impact is strongest in tropical regions, which are more likely to experience the harshest effects of global warming.

Lower crop yields increase the competition for remaining crops. And rising prices mean that many people cannot afford to buy food to compensate for resources lost because of climatic shifts. In countries that lack a social “safety net,” the only alternative in many cases is to obtain food through stealing, looting and — frequently — fighting over fertile land.

Anecdotal evidence from eastern Africa and the Middle East, at least, supports this theory. Attempts to measure the linkages between climate change and armed conflict, however, have yielded mixed results, with some studies at least partly reaffirming these connections and others debunking them.

Some regions adapt to climate conditions better than others

Studies of the “Green Revolution” movement of the 1960s suggest that regions such as Asia were far more successful than Africa at adopting drought-resistant crops, which improved food security and helped offset the risk of war.

Similar efforts in sub-Saharan Africa and the Middle East were weak and generally unsuccessful until the late 1980s.

These efforts met with limited success because of the types of grain available and other socioeconomic complexities, which left these regions food insecure. Had Syria successfully adopted drought-resistant crops, for instance, the social unrest of 2011 might have taken a different, less-violent course.

As researchers continue to debate how climate change and its effects on global food stocks will impact food security in future decades, short-term environmental “shocks” such as droughts or floods have become more frequent in many parts of the world and are a potentially salient cause of armed conflict.

These environmental disturbances can lead to sharp price increases that, in turn, can cause another well-established tradition: the food riot, when civilians take to the streets to protest high food prices.

Low-income countries are particularly susceptible because high food prices in these situations have an especially destabilizing effect. In these countries, high food prices expose the government’s lack of ability to shield consumers. They also create opportunities for civilians to mobilize against the regime.

Even in locations where food is sourced locally, drought-induced shocks may incite violence against civilians when rebel groups seek to appropriate local food supplies. My research documents this happening not only in the Syrian conflict but also in India and Thailand during a 2004 drought. Riots, protests and massacres are among the types of unrest that can lead to civil war — and all can be linked to food conflicts.

How can an abundance of food lead to war?

Food scarcity, however, is only one aspect of food security. Whether people have easy access to food resources is also important. So even in countries where plenty of food is available, a large share of the population might still go hungry.

As Nobel Laureate Amartya Sen notes, “Starvation is the characteristic of some people not having enough food to eat. It is not the characteristic of there being not enough food to eat.”

Grievances over food and the necessity to secure access to food resources can motivate marginalized groups to participate in rebellions and wars. A number of scholars are researching how inequitable access to food affects violence within the state. As Ben Bagozzi and I show in a recent paper, armed actors worldwide are motivated to fight over local food resources.

Here’s why these conflicts tend to happen in regions with more food crops, not less. For rebel groups, securing — and controlling — food resources is vital for the insurgency to advance. And when the government is slow or unable to supply combat rations, state forces also may be forced to extract food supplies from the local population,

So scarce food resources in a region locked in conflict act as both fuel and reward for hungry combatants. Access to more local food resources, especially in the case of rebel groups, can also be used to attract recruits, as happened in Sierra Leone and Somalia. Regions where wheat and barley are grown are also an important source of support for the Islamic State in Iraq and Syria.

The focus on how the demand for food resources influences armed conflict complements the research done on the effects of food scarcity. It also explains why agricultural areas see more violence. In these regions, individuals live largely on locally grown food. If the government’s safety nets are mismanaged or weak, those who control access to food can more easily recruit individuals and operate for a longer period of time.

And this also explains why there is an uptick in violence during times of more rainfall — for instance, in sub-Saharan Africa. By providing armed groups with an added motivation to fight as well as the ability to expand their numbers and strength, local food security can therefore shape global conflict patterns.

Ore Koren is a PhD candidate at the University of Minnesota and a Jennings Randolph Fellow at the United States Institute of Peace.