All spring it's been snowing in California’s Sierra Nevada -- a steady onslaught of storms dumping foot upon foot of fresh powder on the peaks. Local weathermen and state water officials are hailing the late-season squalls as a boon to the state's water supply. They don't quite end the three-year statewide drought, the experts say, but they bring this year's statewide snowpack to right around normal.
Welcome as they may be, the spring storms are just a temporary break in a weather pattern that, without attention, will become a water crisis. An increase in temperature over the last century is affecting climates and ecosystems worldwide. In the Sierra, rising temperatures are taking a particular toll on the snowpack. The results affect far more than ski bums. The winter snow that blankets these granite peaks acts as a reservoir, freezing and holding back the water content until the spring sun warms the slopes and melts the snow. The rivers that flow out of the Sierra provide 65 percent of California's developed water supply.
This historic water regime is in flux. As temperatures rise, snow is falling higher on the Sierra slopes and rain is drenching lower elevations that historically got snow. The snow that does fall is melting earlier. Climate scientists predict the Sierra snowpack will decline by as much as 40 percent by 2050, and by up to 90 percent by the end of the century. The timing of the peak snowmelt in the Sierra Nevada has been getting earlier and could occur a full two weeks earlier by 2100.
For skiers that means a shorter ski season. By the end of the century, it could be only seven weeks long, climate scientists say. They predict a shorter season for river rafters, too. The combination could deprive local economies of millions of dollars in tourist revenue.
The downstream impacts are even more ominous, fueling the state's ongoing water crisis. A reduced snowpack means less water for agriculture, California's economic mainstay. The great Central Valley has already seen a 25 percent reduction in the spring runoff. That will affect anyone who eats the fruits, nuts, grains and dairy products grown here, where eight percent of the nation's crops are produced. It will also affect taxpayers. Providing a reliable water supply to Californians could cost the state an additional $560 million a year by 2085. Climate change is also projected to increase the number and size of wildfires by as much as 128 percent.
Communities throughout the Sierra Nevada are working to adapt to the effects of climate change in a way that protects alpine wildlife and ecosystems as well as statewide water supplies. Led by the Sierra Nevada Alliance, they have embarked on hundreds of local planning efforts that include reviewing timber harvest plans, restoring watersheds, relicensing hydroelectric power facilities and updating county general plans. Part of the challenge is persuading state officials to recognize the importance of protecting the watersheds that provide so much of the state's water supply.
Meanwhile, the storms that are bringing temporary relief to the region are backed up over the Pacific just waiting to continue their dramatic deluges. So let the spring snow fall! Keep the skis handy. It could be worse.