February 6, 2014 8:00 AM EST

When it’s completed, the Grand Ethiopian Renaissance Dam on the Blue Nile will be the largest hydropower project in Africa, supplying 6,000 megawatts of much needed clean electricity to a power-starved region. But that’s if it’s completed. Construction of the dam is under threat because Egypt and Ethiopia, two countries that share the Nile, have been locked in an escalating dispute over how to control the flow of the river. (Egypt is almost completely dependent on water from the Nile, but other North African countries have bristled over Cairo’s historical hold over the river.) There are concerns that the diplomatic disagreement could even spill over to open conflict. Never mind the dam — in North Africa, water could mean war.

At least that’s what we’re supposed to think. The idea that the next world war will be fought over water is now all but taken for granted, recited by environmentalists and generals alike. But a look at the historical evidence indicates that’s not the case — and instead offers hope that water disputes could be an avenue to peace, not war.

Water experts Sandra Postel and Aaron Wolf, writing in Foreign Policy, found that there hasn’t been an actual war between two states over water for about 4,500 years, back when Lagash and Umma, two Mesopotamian city-states in what is now Iraq, took up arms over boundary canals. More than 3,600 separate water-related treaties were signed between the years 805 and 1984. Postel and Wolf further concluded that two-thirds of the 1,831 water-related events between multiple countries in the second half of the 20th century could be characterized as cooperative. India and Pakistan have abided by the World Bank – arbitrated Indus Waters Treaty since 1960, and none of the three wars the bitter rivals have fought were caused by water disputes. Even as Palestinians and Israelis kill each other, water professionals on both sides interact through the Joint Water Committee, established by the Oslo II Accords in 1995. In December, Israel, Jordan and the Palestinian Authority signed a major deal that calls for the construction of a large desalination plant and a new pipeline to the Dead Sea, with the benefits shared by all three entities.

Freshwater is a resource that is hard for any one nation to control, which is why diplomacy — however fraught — has been the usual response to water disputes. And it’s important to remember that most of the water we consume is actually virtual, embedded in the goods we consume, like fruits or vegetables. (Americans, for instance, use a thousand times more water to grow their food each year than they use to drink.) Arid countries like Israel and Egypt have long since outgrown their domestic water supplies. In 2009, science writer Helen Barnaby calculated in the journal Nature that the roughly 10 million people who live between the Jordan River and the Mediterranean Sea would need 10 billion cu m of water per year to grow all their food domestically. In reality, they have only about a third of that amount. They make up for that shortfall with virtual water, in the form of imported food.

There is more virtual water flowing into the Middle East each year in the form of imported grain than water flowing down the Nile to farmers in Egypt — the same farmers who are so worried about the impacts of the Grand Ethiopian Renaissance Dam. Nations cooperate on water through trade and treaties because they have no other choice. And that’s a good thing: it means that water is one area in which even fractious countries are forced by their own needs to negotiate with one another.

That doesn’t mean water scarcity isn’t a major global challenge and won’t be an even bigger one in the future. Global population growth — especially in already arid countries in the Middle East and sub-Saharan Africa — and climate change will only make water scarcer, which in turn could push teetering states over the edge. In Egypt, chronic water shortages and rising food prices have contributed to the state of crisis over the past two years, and Ethiopians have some of the lowest access to potable water in the world. Chances are the two countries will eventually work out their differences over the Nile without resorting to war, as nations almost always do. But if they can’t provide their restive citizens with enough water to live on — real or virtual — they may be reduced to nations in name alone.

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