Water, water everywhere, but not enough to farm

Robert Frederick, writing for PNAS:

Today, there are already several regions around the world where demand for food and water exceed local supply. But human populations continue to grow in these regions because of the global market for food: exporting food also virtually transfers the water needed to grow that food—called “virtual water”—from production areas to consumption areas. The problem, then, is what happens when the water-rich countries have to limit their virtual-water exports in order to meet the demands of their own growing populations. As Suweis et. al. have calculated in a new Early Edition PNAS paper, the resulting decline of trade-dependent populations could happen as early as 2030, just a few years after von Foerster’s doomsday.

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