The Earth is getting saltier, which threatens freshwater supplies, a new study shows

On icy roads, avoiding rock-salt helps keep fresh water safe. Wisconsin
is experimenting with cheese brine. (Illustration via Modern Farmer )

Humans have disrupted the Earth's "salt cycle," resulting in saltier soil and "potentially dangerous consequences for drinking water supplies, crop production, and ecosystems," reports Kate Yoder of Grist. "That's according to a new study published in the journal Nature Reviews Earth & Environment. It's the first time scientists have documented the extent to which humans have changed the salt content of the land, water, and air across the globe."

Among their findings, "Researchers in Maryland and four other states found that 2.5 billion acres of soil around the world have gotten saltier, an area roughly the size of the entire United States, and it’s stressing out plants," Yoder explains. "Salt is even getting kicked up into the air: In arid regions, 'lakes are drying up and sending plumes of saline dust into the atmosphere,' such as the Aral Sea in Central Asia," the study says.

While all living things on Earth require water, more than 100,000 species, including humans, need fresh water. Yoder reports, "Salt pollution presents an 'existential threat to our freshwater supplies,' according to the study. It can corrode drinking water pipes, exacerbating lead pollution in water supplies, as it did in Flint, Michigan. Salinization has been supercharged by a host of factors: irrigation, deicing roads, mining, wastewater treatment, and even the use of salt-laden household items like detergent. . . . . Researchers found so much of it, they worried that salt could cause 'serious or irreversible damage across Earth systems.'"

Water sources along the coast face unique threats. "Sea-level rise can send salty ocean waters into the groundwater, making it undrinkable," Yoder reports. "It only takes 2 or 3 percent seawater to make the groundwater undrinkable, and removing salt from water is difficult and expensive."

Western states that rely on snowpack melt for fresh water can face problems from saline dust. Yoder notes, "Since salt can alter the freezing temperature of water, this salt-rich dust could accelerate snowmelt."

Road salt does the most harm. "That salt helps make roads less icy, but it eventually runs off and contaminates streams and drinking water," Yoder writes. "There are methods available to lessen the environmental impact while helping prevent cars from skidding across roads. . . . Wisconsin, playing to character, has incorporated cheese brine, preferably from provolone and mozzarella, into its efforts to deice roads with less salt."