The US has pumped so much groundwater that it's literally splitting the ground open across the American Southwest

• The United States has been pumping so much groundwater it's splitting the ground open.
• The giant cracks occur when the ground sags and splits as natural water levels lower beneath it.
• Freshwater from groundwater is used for everything from food to farming.

The United States has been pumping so much groundwater that the ground is beginning to split open across southwestern parts of the country for miles on end.

These giant cracks, aka fissures, have been spotted in states including Arizona, Utah, and California.

Groundwater is one of the main sources of freshwater on Earth — it provides almost half of all drinking water, and about 40% of global irrigation.

But humans are pumping groundwater faster than Earth can naturally replenish it. 

When too much groundwater gets pumped up from the natural aquifers below the surface, it causes the land to sag and create these cracks, Joseph Cook, who researches Earth fissures at the Arizona Geological Survey, told Insider.

The fissures "are not a naturally occurring thing," Cook said. "It's something we've caused to form."

The cracks are signs of tension in the Earth, Cook said. They rim large flat areas of ground that sunk when it lost the support of groundwater.

Fissures commonly occur in the basins between mountains and can damage homes, roads, canals, and dams as well as threaten property values, livestock, and humans.

Arizona has known about this problem for a long time and has been monitoring it since at least 2002.

There are 169 miles of fissures currently charted by the Arizona Geological Survey.

A national crisis

A recent New York Times investigation noted that the fissures are evidence of a national crisis. 

The Times investigated water levels at tens of thousands of sites across the US. It reported that the aquifers, which supply about 90% of US water systems, are being depleted so severely they may not be able to recover.

Almost half of the monitored sites have "declined significantly" in the past 40 years. And four out of every 10 sites hit "all-time lows" in the past decade as American groundwater pumping outpaces water replenishment, per the Times.

Aquifers could take centuries or even thousands of years to recover if they can recover at all, the Times reported.

Some sites in Arizona are already beyond saving, according to Cook.

Our water use has been so consistent and extreme that it hasn't allowed enough time for rainwater to replenish underground aquifers, he said. 

"Basically, some of these basins in Arizona are so far beyond that point that it's never going to bounce back," Cook added.

Climate change makes it worse

When climate change is added into the mix, the makings of a "crisis" are well underway, University of Tulsa law professor and water expert Warigia Bowman told the Times.

As global temperatures rise, rivers shrink, forcing farmers to rely even more on groundwater reserves for freshwater, per the Times.

The Colorado River, which supplies freshwater for farmers across the Southwest including Arizona, has already declined by nearly 20% since 2000.

And if global temperatures in the Colorado River Basin rise another 2-5 degrees Fahrenheit by 2050, as predicted, it could reduce river flow by 10% to 40%, according to The Climate Reality Project.

How did it get this bad?

One of the main issues in addressing over-pumping is the lack of regulation that exists across the country.

The federal government has almost no regulations against groundwater pumping, and individual states have weak, variable rules from region to region, per the Times.

Arizona is no exception. For most of its history, groundwater has been unregulated in much of the state, operating on a first come first serve basis, according to the National Audubon Society.

This means no limit on how much groundwater can be used, and people can simply drain the groundwater until it runs out, Cook said.

Also, it's rare to find studies of groundwater on a national scale. Most of the time research focuses on a single source or region.

As a result, the severity of excessive groundwater pumping nationwide is not as easy to recognize and may help explain why regulation on pumping is so limited.

Meanwhile, damaging practices, like farming crops in dry areas, are allowed to continue.

If we don't change our habits and allow underground aquifers to naturally replenish themselves, these fissures will keep growing, Cook said.