California' ongoing drought may be causing the state the shrink -- or at least lose mass -- as it dries out and water storage levels drop, new satellite images indicate.
NASA's Gravity Recovery and Climate Experiment (GRACE) satellites have provided colorful but disturbing images of just how severe the declines in water storage have been over the last decade or so.
Different colors in the GRACE satellite images indicate changes in mass linked to variations in water amount below or on the surface of California, scientists say.
In the worst-hit central area of the state, where heavy groundwater pumping has been necessary to support agricultural activities, the Central Valley's river basins lost a combined 4 trillion gallons of water annually between 2011 and 2014, NASA reported.
In the satellite images, colors assigned to the Central Valley between 2002 and 2014 changed from green to orange to an alarming red, indicating a severe reduction in mass due to declining water storage.
More than 95 percent of California is under severe or exceptional drought, with 58 percent under the highest "exceptional" drought level as defined by the U.S. Drought Monitor.
The federal government has declared all of California's 58 counties to be natural disaster areas.
Gov. Jerry Brown declared a drought emergency earlier this year, and water agencies have been considering a daily water allocation amount for each California household.
"The drought crippling California is by some measures the worst in the state's history," the National Science Foundation has said.
As the state suffers, a Stanford University study funded by the NSF has confirmed that growing evidence supports the contention that "atmospheric conditions associated with the unprecedented drought in California are very likely linked to human-caused climate change."
The researches said a combination of computer models and statistical analysis shows a long-lasting region of high atmospheric pressure over the Pacific Ocean, which has diverted storms that traditionally bring California much of its water away from the state, was much more likely to exist in the current modern level of greenhouse gas emissions.
"Our research finds that extreme atmospheric high pressure in this region--which is strongly linked to unusually low precipitation in California--is much more likely to occur today than prior to the emission of greenhouse gases that began during the Industrial Revolution in the 1800s," says Stanford climate scientist Noah Diffenbaugh.
Climate change is being blamed for decreased precipitation in many areas of the world, including the Mediterranean and much of the U.S. southwest, the researchers note in their study published in the Bulletin of the American Meteorological Society.