From India to Texas, people are rapidly depleting their valuable stores of groundwater — leading to the possibility that aquifers may be emptied within decades, a NASA researcher has warned.

In a commentary published Wednesday in the journal Nature Climate Change, Jay Famiglietti, who has helped lead the use of a NASA satellite system to detect groundwater changes around the world, warned of dramatic consequences to come if changes are not made to the way that societies manage water supplies.

Currently, Famiglietti told Mashable, management of global groundwater stores is inadequate to nonexistent, as governments focus on regulating surface water supplies while tapping underground aquifers as much as they want to.

“Our overuse of groundwater puts our overall water security at far greater risk than we thought,” Famiglietti says.

GRACE satellite data showing California's groundwater depletion in recent years. Image: NASA JPL

Unlike surface water, which is replenished through precipitation, groundwater can take centuries to recharge. Yet humans are depleting groundwater at rates that far exceed the pace at which this water can be replenished.

Think of it this way: groundwater is analogous to a pension, a long-term investment that takes many years to pay off. If you withdraw more than you put in, you'll go bankrupt in the long run. Dams and reservoirs, meanwhile, are more like a checking account.

"Groundwater is being pumped at far greater rates than it can be naturally replenished, so that many of the largest aquifers on most continents are being mined, their precious contents never to be returned," Famiglietti, a researcher at NASA's Jet Propulsion Laboratory in California, wrote.

Famiglietti has used NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite system, which is capable of detecting the most subtle changes in Earth's gravitational field to spot land elevation changes, and thus water depletion, to publish a number of studies on groundwater in recent years.

During the summer, for example, he contributed to a study that revealed that water users throughout the Colorado River Basin are tapping into groundwater supplies to make up for the lack of adequate supplies of surface water.

The study found that more than 75% of the water loss in the Colorado River Basin since 2004 came from groundwater.

GRACE showed that between December 2004 and November 2013, the Colorado River basin lost nearly 53 million acre feet of freshwater, which is double the total volume of the country’s largest reservoir — Lake Mead in Arizona. More than three-quarters of the total — about 41 million acre feet — was from groundwater.

Other GRACE data has shown that the Sacramento River and San Joaqin River basins have lost a total of 4 trillion gallons of groundwater per year, which has caused the land surface to sink.

NASA's Grace satellites measured the depletion of groundwater in northwestern India between 2002 and 2008. Image: NASA

Groundwater, Famiglietti told Mashable, accounts for more than half of the irrigation water used to grow the world's food. Aquifers of particular concern to Famiglietti include the North China Plain, Australia's Canning Basin, the Northwest Sahara Aquifer System, the High Plains and Central aquifers in the U.S., and aquifers between northwestern India and the Middle East.

"Because the gap between supply and demand is routinely bridged with non-renewable groundwater, even more so during drought, groundwater supplies in some major aquifers "will be depleted in a matter of decades," Famiglietti wrote.

Famiglietti says that groundwater depletion in northwest India is at the top of his list of concerns, in part because of the population growth.

Water shortages could lead to political instability

As climate change redistributes water around the planet, with wet areas getting potentially wetter and dry areas drier, it could further stress water supplies, Famiglietti said. This could lead to conflicts, particularly in countries that lack resiliency to such shocks.

A key factor in groundwater depletion is that water laws do not do much to manage aquifers. In California, the ongoing drought has forced state leaders to pass a bill meant to track groundwater supplies and encourage their sustainable use — but not before the state has actually sunk in elevation, because so much groundwater has been used for agriculture.

The consequences of poorly managing groundwater supplies in the coming decades could be extremely disruptive, in the form of declining agricultural production, reductions in energy generation and the possibility of huge spikes in food prices.

“The handwriting is on the wall for all the bad things that can result from that," he said.