WATER SECURITYGroundwater Is Drying Out, Heating Up, and Causing Sea Level Rise
Overuse has created zones of “mega-drying” around the world —and caused more sea level rise than Greenland’s ice sheet.
The Verde River is one of the last free-flowing rivers in Arizona, winding through what’s known as the Verde Valley before feeding into the Salt River. Agriculturally, the valley is relatively fertile, supporting crops like sweet corn, alfalfa, peaches, and pecans, as well as a small wine industry. Recently, though, residents have found that the water below their feet is drying up.
Faith Kearns grew up in the area, and her mother still lives in her childhood home. This summer when they tried to turn on the garden hose, which is connected to their groundwater well — a common source for household water in the region — nothing came out.
“We’ve had some challenges here and there, but it’s definitely gotten worse over the last few years,” Kearns, who is the director of research communications for the Arizona Water Innovation Initiative at Arizona State University, told Grist.
Arizona is far from the only place where groundwater is in big trouble. According to a study released last week in the peer-reviewed academic journal Science Advances, fresh water has been declining at an alarming rate since researchers began observing global groundwater in 2002, creating areas of “mega-drying” that cover much of the Northern Hemisphere.
Although climate change is a contributing factor, with elevated temperatures sapping moisture out of the ground, the main culprit is overpumping of groundwater. After that water is put to human use, it escapes into the ocean where, the study found, it has contributed more to sea level rise than the melting of the Greenland ice sheet. Total water storage losses on land, of which groundwater is the largest component, account for 44 percent of global mean sea level rise, compared to about 37 percent from Greenland and roughly 19 percent from melting in Antarctica.
The fact that “human management of water resources has such a significant effect on sea level rise, I think that has not been seen before,” said Martin Stute, a hydrologist at Barnard College who did not contribute to the study. He pointed out that even the National Oceanic and Atmospheric Administration is still characterizing the transfer of groundwater to the ocean as a fairly minor addition to sea level rise.
