By Eric Holthaus • Slate
SEQUOIA NATIONAL PARK, CALIF.
Any story of California's convoluted water system must start where the water does: with snow in the mountains.
And this year, in many places, there just isn't any. New data show that California will be starting the summer dry season with a snowpack at about the lowest levels since record keeping began nearly a century ago. The data were collected as part of California's annual snowpack survey across the vast Sierra Nevada.
According to the U.S. Geological Survey, the Western United States gets as much as 75 percent of its water supply via snowmelt.
For cities and farms across California, the numbers show this is shaping up to be a summer like none other.
Nearly one-quarter of the latest measurements (56 of the 233, to be exact) show a snowpack that is less than 10 percent of what it usually is this time of year. At least a dozen had no snow at all, even above 7,000 feet elevation. Averaging all the measurements, the state is starting off the dry season with about 25 percent of the typical April 1 snowpack — which is where it started in 1977, the year with the least snow measured in California.
As you might guess, a warming world also means a world with less snow. After an exceptionally warm and dry winter, this year's snowpack was only 9 percent of average on slopes below 6,000 feet in elevation. Scientists expect these lower-elevation mountainsides to be the first to lose their snow as the climate warms.