By Rong-Gong Lin II
21 August 2014
(Los Angeles Times) – The ongoing drought in the western United States has caused so much loss of groundwater that the Earth, on average, has lifted up about 0.16 inches over the last 18 months, according to a new study.
The situation was even worse in the snow-starved mountains of California, where the Earth rose up to 0.6 inches.
Researchers from UC San Diego’s Scripps Institution of Oceanography and the U.S. Geological Survey estimated the groundwater loss from the start of 2013 to be 63 trillion gallons — the equivalent of flooding four inches of water across the United States west of the Rocky Mountains.
The study, published online Thursday by the journal Science, offers a grim accounting of the drought’s toll.
“We found that it’s most severe in California, particularly in the Sierras,” said coauthor Duncan Agnew, professor of geophysics at UC San Diego’s Scripps Institution of Oceanography. “It’s predominantly in the Coast Ranges and the Sierras showing the most uplift, and hence, that’s where we believe is the largest water loss.”
That’s also about how much ice is lost from the Greenland ice cap every year from global warming. [more]
By Adrian Antal Borsa, Duncan Carr Agnew, Daniel R. Cayan
8 August 2014
ABSTACT: The western United States has been experiencing severe drought since 2013. The solid earth response to the accompanying loss of surface and near-surface water mass should be a broad region of uplift. We use seasonally-adjusted time series from continuously operating GPS stations to measure this uplift, which we invert to estimate mass loss. The median uplift is 4 mm, with values up to 15 mm in California’s mountains. The associated pattern of mass loss, which ranges up to 50 cm of water equivalent, is consistent with observed decreases in precipitation and streamflow. We estimate the total deficit to be about 240 Gt, equivalent to a 10 cm layer of water over the entire region, or the annual mass loss from the Greenland Ice Sheet.