Study: Climate changes could reduce Sierra snowpack

Thursday, Oct. 16, 2003 | 3:52 a.m.

REGIONAL ED: Attribute to nvren

RENO, Nev.- A new report raising concerns about the impact of climate change on the snowpack in the Sierra says global warming has the potential to push the snow elevation up 500 feet in the decades ahead.

The dramatic changes are expected at a time increased population is already increasing demand for water in the region, said the study released Thursday by the Lake Tahoe-based Sierra Nevada Alliance.

The report, "Troubled Waters for the Sierra," cites studies by climatologists and university researchers. It predicts temperature increases ranging from 2.5 degrees to 10.4 degrees during the next century.

The warmer temperatures in the Sierra would cause more precipitation to fall as rain at altitudes where it previously fell as snow. That would create more runoff flowing downstream during the winter, providing less water over the summer when it is needed most, the study said.

"It's a troubling situation if we continue to keep our heads in the sand and pretend it's not happening," said Joan Clayburgh, the alliance's executive director.

"Reno, Gardnerville and Minden all depend on that snowpack, and we're concerned about it shrinking," she told the Reno Gazette-Journal.

Officials for the Reno area's primary water supplier insist that even if global warming causes problems in the future, the metropolitan area's water supply is protected by plentiful storage at high altitudes.

"Might it occur? It might," said Lori Williams, general manager of the Truckee Meadows Water Authority. "Do we have time to react to it? We do."

The report follows the release of a new survey of Sierra glaciers that shows ice slabs on many of the mountain chains highest peaks are shrinking.

That survey of seven Sierra glaciers concludes all are smaller than they were a century ago, said Hassan Basagic, a graduate student from Portland State University in Oregon.

One of them, Darwin Glacier near Bishop, Calif., is between 50 and 100 feet thinner than in the early 1900s, the survey shows.

John Tracy of Reno's Desert Research Institute said the issue of climate change and water supplies deserves more attention. Tracy appeared Oct. 1 before Washoe County's Regional Water Planning Commission to propose such a study.

"We'd better be able to put it in our plans right now because it is something that's going to manifest itself in the next century, definitely," Tracy said.

The alliance's report cites research by the Scripps Institute of Oceanography, the Lawrence Berkeley National Laboratory, the U.S. Geological Survey and the University of California, Santa Cruz, among others.

The combination of climate change and growth could spell trouble, Clayburgh said.

Six months ago, the Truckee Meadows Water Authority cut back its drought reserves to serve additional growth.

Population across the region is expected to skyrocket, with growth rates in many of California's Sierra Nevada counties expected to rise between 100 percent and 500 percent from 1990 levels by 2020, the report concludes. Washoe County's population is expected to rise to nearly 440,000 by 2020, an increase of about 21 percent from this year.

"No one has put the puzzle pieces together before and its not a pretty picture for our water future," Clayburgh said.

Her group is calling for a number of steps to address the situation, including factoring in climate change and growth into general plan updates by affected counties and in the relicensing of hydroelectric projects on the Sierras rivers. It also favors the creation of a California Sierra Nevada Conservancy to manage conservation efforts along the mountain chain.

Information from: Reno Gazette-Journal