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Study Says Extreme Drought Causes Western US to Rise

The current Southwest drought has brought many problems to residents and businesses in California including water conservation restrictions and fines, decreased agricultural crop production and fewer recreational opportunities.

A new problem has surfaced as a result of the historic drought: The earth's crust is slowly rising because groundwater, which kept it weighed down, has disappeared.

The estimated loss of 63 trillion gallons of water raised California mountains by more than a half inch (15 millimeters) and on average, 0.15 inches (4 mm) across the western United States, researchers at the Scripps Institution of Oceanography at the University of California-San Diego said.

The water loss is equivalent to the yearly water loss of the Greenland Ice Sheet, the researchers said.

The Scripps study, done in conjunction with the U.S. Geological Survey, was reported in the Aug. 21 online edition of the journal Science.

Scripps researchers analyzed GPS data used for earthquake monitoring in the region from 2003 to 2014. All the stations moved upwards in the most recent years, which coincide with the drought, according to a Scripps news release.

"These results quantify the amount of water mass lost in the past few years," researcher Dan Cayan said in a news release. "It also represents a powerful new way to track water resources over a very large landscape. We can hone in on the Sierra Nevada mountains and critical California snowpack. These results demonstrate that this technique can be used to study changes in fresh water in other regions around the world, if they have a network of GPS sensors."

It will take 6 to 9 inches of rain over a four-week period for the California water conditions to stabilize, according to Senior Meteorologist Jack Boston, who quoted data from the Palmer Drought Severity Index.

Some areas need up to 12 inches of rain to reverse the drought.

An expected weak El Niño, also known as an El Niño Modoki, will not help California's drought, Boston said.

Higher sea surface temperatures will be farther west in the central tropical Pacific, keeping some of the best precipitation prospects away from California, he said.

"California will have a dry winter," he said. "They're in rough shape. You need a moderate to strong El Niño to bring sizable storms to California; otherwise, the storms will pass by California and go into Oregon and Washington."

Scripps researcher Duncan Agnew also noted that the rising crust has virtually no effect on the San Andreas Fault and doesn't increase the risk of earthquakes.