Drill deeply into most of the conflicts and civil wars of the past thirty years and you will find, underneath all the political, ideological, ethnic and religious divisions, people fighting over access to food, land and water.

These resources are essential to our survival—and our children’s. This simple fact is, and always has been, a primary casus belli: the emotional spark that fires the tinder of mutual antagonism between two or more competing groups or even nations. It was present in Dafur, the Rwandan genocide, the Balkans, the Horn of Africa and many other trouble spots around the globe. It triggered regime changes in Egypt and Tunisia (as well as in Russia and France, a century or two ago).

Serious disputes over food, land and water are also notably absent from Australasia, from northern Europe, from North America where food is plentiful. And so are wars, in those places. People who enjoy a sufficiency of these basic essentials for life are less inclined to resort to organised violence to solve their differences. As former US President (and farmer) Jimmy Carter once observed ‘There can be no peace until people have enough to eat. Hungry people are not peaceful people’.

In modern times hunger has barely entered the calculus of conflict, except as one of its consequences. Few analysts have grasped the potent role which it plays in triggering political and national disintegration, governance failure, internecine fears and hatreds that build into conflict, and even international wars. This is beginning to change, with the growing instability in the world food supply.

Today the world food supply is insecure because it depends on critical inputs, all of which are now starting to run short or become unaffordable to farmers: land, water, oil, fertiliser, farming technology, fish, finance and a stable climate, especially. As a result, world food output no longer keeps pace with growth in demand for food—and the risks of regional famines and conflicts are growing. Climate change, in particular, could cut grain production by up to half in key areas of the globe by the mid-century, precipitating international crises, vast outpourings of refugees and wars, possibly even nuclear.

Today, defence thinking and strategy need to embody food, land and water in the same way that they embody the other sinews of war. Without a solution to hunger, a solution to conflict is unlikely: the two go hand in hand. Today the world spends around $50 billion a year on food science—and $1.7 trillion on new weapons: as a species, we evidently consider it thirty times more important to find better ways to kill one another than to feed one another.

Yet a sufficiency of good food can ensure peace in ways that a sufficiency of weapons cannot. If the world is serious about peace, about establishing stable governance and democracy and all the benefits which they bring such as education, health care and opportunity for women and children, then it will attend to the necessity to feed humanity above all other priorities. It will devote one tenth of the world’s military budget to the task of securing peace through ensuring the global food supply, because in the world of the future, food scarcity and the conflicts that flow from it threaten the physical and economic security of us all, not only the hungry.

Julian Cribb is a former newspaper editor and a science writer. He is the author of The Coming Famine: the global food crisis and what we can do to avoid it. Image courtesy of Flickr user Agustin Rafael Reyes.