California’s Drought Is Over, but the Rest of the World’s Water Problems Are Just Beginning – TOM PHILPOTT APR. 8, 2017 6:00 AM


And the global food trade means that we’re all in it together.

After California’s wetter-than-normal winter—and the official end to its drought—you’re probably not thinking much about water scarcity and the food supply. But our food-and-water woes go well beyond the Sunshine State’s latest precipitation patterns, as this new Nature study from a global team of researchers—including two from the NASA Goddard Institute for Space Studies—shows.

Water reserves in California’s Central Valley are still in a long-term state of decline.

The paper notes that the globe’s stores of underground water, known as groundwater—the stuff that accumulates over millennia in aquifers—is vanishing at an “alarming” rate, driven mainly by demand for irrigation to grow crops. You can think of such reserves as “fossil” water, since it takes thousands of years to replenish once it’s pumped out. Once it’s gone, some of the globe’s key growing regions—the breadbaskets for much of Asia and the Middle East—will no longer be viable. Here in the United States, we rely heavily on California’s Central Valley for fruit, vegetables, and nuts—which in turn relies on some of the globe’s most stressed aquifers for irrigation. Tapped-out aquifers point to a future marked by high food prices and geopolitical strife.

The Nature researchers found that the most severe depletion is concentrated “in a few regions that rely significantly on overexploited aquifers to grow crops, mainly the USA, Mexico, the Middle East and North Africa, India, Pakistan and China, including almost all the major breadbaskets and population centres of the planet.”

The group mapped global food trade flows from these areas with the most-stressed aquifers—places like the California Central Valley, the Midwest’s High Plains (where farmers have for years been draining the Ogallala aquifer to grow corn and cotton), India’s breadbasket, the Punjab, and China’s main growing region, the North Plain. That these crucial resources are being rapidly used up is well established—for example, see the 2014 Nature paper, using satellite data by NASA water scientist James Famiglietti, which I discussed here.

What the new paper adds to that chilling assessment isn’t comforting to US eaters, or people who look at long-term geopolitical trends. They name the seven countries where farmers are drawing the most from overstressed aquifers: India, Iran, Pakistan, China, the United States, Mexico, and Saudi Arabia. Together, agriculture within these countries is responsible for more than 90 percent of the globe’s irrigation water taken from overdrawn aquifers

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