Groundwater Is Drying Out, Heating Up, and Causing Sea Level Rise
Unless stringent water management policies are implemented on a global scale, the Science Advances study’s principal investigator, Jay Famiglietti, warns that the consequences could trigger extreme political instability, given that 75 percent of the world’s population resides in countries affected by this extreme drying. “What this study makes clear is that the world is looking at incredible sea level rise,” he said. “I think threats to food security and food production [aren’t] receiving enough attention.”
Such policies may not be forthcoming anytime soon. The United States, which sources half of its drinking water from groundwater, has no unifying water management plan, instead relying on a piecemeal local network of regulations. California passed the Sustainable Groundwater Management Act, which aims to regulate water withdrawals and prevent aquifer exhaustion, in 2014, but the state isn’t expected to reach sustainable water use patterns until the early 2040s. Other states like Louisiana and Maine grant landowners “absolute dominion” over groundwater under their property — meaning any landowner can draw endlessly from their well, even at the expense of their neighbor, even as aquifers are depleted and threatened by saltwater intrusion.
In some areas of the country, so much water has already been drained that the aquifers have collapsed in on themselves, explained the study’s lead author, Hrishikesh Chandanpurkar. This causes land subsidence, damage to infrastructure, and compounding sea level rise in coastal areas. Sometimes, the collapse is irreversible, meaning a given region has no chance at recovering their lost aquifer by recharging the groundwater supply. Instead, the dead aquifer becomes a public nuisance, creating large sinkholes that can dot the area like asteroid craters. A recent study by researchers at the University of California, Riverside found that homes built in subsiding regions lost 2.4 percent to 5.8 percent of value compared to homes on more stable ground.
Last month’s study on global groundwater loss was conducted using a pair of NASA satellites collectively known as the Gravity Recovery and Climate Experiment, or GRACE, which Famiglietti referred to as “a scale in the sky,” because the system is designed to respond to miniscule variations in the Earth’s groundwater storage. The genesis of the new research came just after the COVID-19 pandemic, when Famiglietti was working with some colleagues who asked him to review Germany’s groundwater levels.
As he reviewed the data, Famiglietti became alarmed: There appeared to be a tipping point after a particularly strong El Niño event in 2014 caused widespread drought. The Western United States, Europe, and Central and South America all saw vastly increased drying during that period. Global dry areas are currently growing by an area roughly twice the size of California every year, even after the end of the drought.
Other research shows that groundwater depletion is only part of the story: What’s left of that water, another recent study in the peer-reviewed journal Nature Geoscience shows, is heating up. Study author Susanne Benz explained that the effects of global warming have started to penetrate underground, 40 or 50 meters deep in some areas. Warming could degrade groundwater quality by increasing microbial production, and warmer water makes it easier for dangerous chemical elements usually locked safely away in rock, such as arsenic, to dissolve into drinking water. It could also upend freshwater habitats in lakes, ponds, and rivers — allowing more harmful algae blooms and killing off aquatic life.
The larger problem, Stute explained, is making it clear to people that groundwater — like oil — is a finite resource. “It will be gone. What do we do then?” he said. “In principle, we are aware of [these] issues, and we’re not doing anything.”
A previous version of this article misstated the percentage groundwater contributes to sea level rise and Jay Famiglietti‘s, Hrishikesh Chandanpurkar‘s, and Faith Kearns’ titles, Famiglietti is the principal investigator on the study, not the lead author. Hrishikesh Chandanpurkar is the lead author on the study. Kearns is the director of research communications for the Arizona Water Innovation Initiative at ASU, not for Arizona State University itself.
Rebecca Egan McCarthy is Climate News Reporting Fellow at Grist. This story was originally published by Grist. You can subscribe to its weekly newsletter here.
