High Country News
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High Country News

As temperatures rise, Arizona sinks

Climate change and unregulated wells are depleting the West’s groundwater reserves.

The graphic shows one farming area and its subsidence zone, southwest of Salome.

Arizona is sinking. The combination of groundwater pumping and warmer temperatures is shrinking aquifers and lowering water tables. And as the land subsides, fissures open, 2-mile wounds that devour infrastructure and swallow livestock. Four of Arizona’s five economic pillars — cattle, cotton, citrus and copper — use huge amounts of water, while the fifth, the state’s climate, is changing, making water scarcer. Development and growth are intensifying the problem, despite relief from state laws and the existence of the Central Arizona Project, which began delivering Colorado River water to Phoenix and Tucson in the 1980s.

Today, where subsidence is worst, groundwater pumping isn’t even monitored, and big agricultural and anti-regulatory ideologues try to stymie any efforts to keep tabs on how much water is being pumped. Big corporate farms are sprouting in areas without CAP water and virtually no regulation on groundwater pumping. More and more farms produce alfalfa, one of the thirstiest crops on Earth; the number of acres in hay production more than doubled between 1987 and 2017, and tonnage nearly tripled. Meanwhile, Arizona is getting even hotter.

That kind of heat, according to a recent study published in Nature Communications, strains groundwater reserves, too. The study “Evapotranspiration depletes groundwater under warming over the contiguous United States” found that warming also stresses plants, forcing them to suck up more groundwater and further lowering water tables. “These changes show that even the most moderate warming projection can shift groundwater surface water exchanges and lead to substantial and persistent storage losses,” the study notes, adding that with just 1.5 Celsius (2.7 Fahrenheit) warming, the nation’s groundwater reservoirs collectively will lose about four times the total volume of Lake Powell over four years.

Read more here: https://www.hcn.org/issues/52.4/infographic-water-as-temperatures-rise-arizona-sinks

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