You see it in the headlines: Yemen, Syria, South Sudan, Nigeria – the world is experiencing a rise in conflict, instability and human suffering. More people are currently displaced from their homes because of violence, conflict and persecution than any other time since the World War II. One of the consequences is that we’ve seen an uptick in the number of hungry people on the planet for the first time in over a decade.

That war and conflict produce poverty and hunger is something that we’ve long understood – it has been proven in every major sustained violent confrontation in human history. By some accounts, more people died in World War II from starvation than from fighting. What we are learning in the context of modern crises is that hunger is not simply a byproduct of war, but can be the root cause of instability. From competition over land and water for food production to violent protest in urban centers from food prices spikes, food-related instability features in many modern conflicts.

Food security is a fundamental requirement of any stable society. Senator Pat Roberts from Kansas once said: “Show me a nation that can’t feed itself, and I’ll show you a nation in chaos.” More and more countries today face this precise challenge. Over 124 million people are in need of lifesaving humanitarian food assistance today, up from 80 million just two years ago.

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Hunger produces profound desperation, the type that can cause a parent to put a child in a raft on a perilous journey to Europe; or that forces a young man with no income, limited opportunity and a hungry family to pick up arms for a cause he doesn’t even believe in. In a comprehensive review of the work on this topic, a new report from World Food Program USA shows that food insecurity has been empirically linked to at least nine separate types of instability, ranging from protest to interstate conflict, with terrorism and civil war in between.

When we think of food-related instability, food riots very often come to mind. Food riots have played a role in the French Revolution and have been captured in headlines worldwide for generations – pasta riots in Italy, tortilla riots in Mexico, bread riots in the Middle East. Americans spend only 10 percent of their income on food, while citizens in the world’s poorest countries spend closer to 60 percent. Global food price spikes can have major effects on political stability in these settings.

Food price spikes were responsible for social unrest in at least 40 developing and middle-income countries in 2008 in what has been termed the “silent tsunami.” These spikes and the resulting unrest are widely recognized as leading to regime change in Haiti during this period. A second wave of price spikes owing to agricultural commodity production shocks in China and Russia in 2011 has also been linked to the rise of the Arab Spring in the Middle East.

We also see food-related instability playing out in conflicts between pastoralists and farmers over dwindling agriculture resources and territory. This is the modern story of the African Sahel. In the decades leading up to the 2003 outbreak of war in Sudan, for example, the Sahel region of northern Sudan had witnessed the Sahara Desert advance southward by almost a mile each year, forcing Arab herders into ethno-African farming communities and producing unrest.

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Price spikes and resource competition are increasingly driven by the impacts of climate change. Climate change disproportionately impacts the agricultural sector –especially in the global south – and is the subject of a growing body of research on the climate-conflict nexus. It is estimated that 80 percent of agricultural production in developing countries does not employ any form of irrigation.

In the lead-up to the civil war in Syria, more than 1 million farmers were affected by crop loss from long-term drought. One author called this “the worst long-term drought and most severe set of crop failures since agricultural civilizations began in the Fertile Crescent many millennia ago.” As a result, the southwestern city of Daraa, situated in one of the traditionally fertile areas of Syria, saw a large influx of migrants and was one of the first sites of social unrest in the country in 2011.

Meanwhile, the rise of Boko Haram in Northern Nigeria has been linked by some to prolonged drought conditions in the Lake Chad Basin of West Africa. In recent decades, the water surface of Lake Chad has shrunk by over 90 percent compared with its size in the 1960s, contributing to a loss of livelihoods and threatening food security in the region. Climate impacts are expected to worsen as the Earth faces a 3 degrees Celsius rise in mean temperature in the coming decades, forcing another 122 million people into poverty and hunger.

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Modern crises are almost never driven by a single cause. But when food insecurity meets with poor governance, a lack of economic opportunity and existing societal grievances, the conditions for conflict to emerge – or re-emerge – can be met.

Legislation has also been introduced to encourage further collaboration between the traditional “instruments” of U.S. foreign power – defense, diplomacy and development – in order to tackle these same root causes.

Breaking the cycle of hunger and conflict is among the great challenges of our day. Doing so, however, begins with acknowledging the link between food insecurity and global instability. Surely, one of the best investments we can make in global stability is to help people who can’t feed themselves or their families.

With the rise in state fragility and a proliferation in conflicts involving non-state actors, the U.S. defense and intelligence communities are beginning to turn their eyes toward non-traditional security threats and root causes of instability like food insecurity. As a salient example, U.S. Marine Corps Gen. Thomas Waldhauser, commander of U.S. Africa Command, said in the AFRICOM 2018 posture statement to Congress, “None of Africa’s challenges can be resolved through the use of military force as the primary agent of change. Therefore, our first strategic theme is that AFRICOM activities directly support U.S. diplomatic and development efforts in Africa.”

This article originally appeared on Malnutrition Deeply. You can find the original here.

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