The drought permeating the western United States has gone from bad to worse over the past year and a half — especially in California. As of two weeks ago, more than half of the state is considered to be in an “exceptional drought,” and the conditions are predicted to cost California $2.2 billion this year, as well as more than 17,000 jobs in the agriculture industry.
If that wasn’t enough, researchers are now reporting yet another consequence of the severe water loss in California and its surrounding states. The entire western U.S. has actually started to rise up. No, not in protest — but geographically.
Scientists at Scripps Institution of Oceanography have found that the recent water shortage has caused an “uplift” effect of approximately four millimeters, or about 0.15 of an inch, in the West. The rise is especially pronounced in California, causing the state’s mountains to rise 15 millimeters, or more than half an inch.
The phenomenon all has to do with the amount of weight being applied to the Earth in a given area. Water in reservoirs and lakes can be pretty heavy, and as the West loses more of it, there’s less weight pushing on the land.
“Think of the Earth as a big rubber ball,” Duncan Agnew, a geophysics professor at Scripps who specializes in studying earthquakes, tells Popular Science. “It’s made of material that is elastic, and if you push on it, it goes in a little bit. If that push is taken away, by water evaporating, there’s less weight on that part of the earth, and it goes up.”
Agnew says they discovered this upward shift after sifting through tons of data collected by their network of GPS stations located in the western U.S., which were set up eight years ago to measure tectonic plate activity. The stations record both horizontal and vertical movements, and the researchers noticed that within the last 18 months (coinciding with the drought), many of the sites had moved up relative to where they had been in previous years.
While all this expanding land may seem scary, Agnew says not to worry. “This will change the stress on faults, but by an amount that’s really small,” he says, not enough to cause any unwanted seismic activity. Plus, land goes up and down all the time for other reasons every day, e.g. from tidal forces or intense monsoons.
Instead, the findings mostly reveal just how much water has been lost within the past year. Through their elevation measurements, the researchers estimate that the western U.S. has suffered a deficit of nearly 62 trillion gallons of water.
“If you had a volume of water the size of the western U.S. that was 10 centimeters thick, that’s how much water has been removed,” says Agnew.
The researchers published their findings in the journal Science.