Water woes

Snowpack in California likely will shrink noticeably during the next 30 years and could, paradoxically, result in increased risk of flooding as well as less water available for agriculture, according to a climate change study from Stanford University researchers.

Published in the journal Nature Climate Change, the study led by climate researcher Noah Diffenbaugh forecasts big challenges ahead for the Western U.S. and California in a projection of Northern Hemisphere snowpack through the 21st century.

There will be less water available for irrigation and farming in the summer and more springtime runoff that levees and dams will have to contend with.

“The Western U.S. exhibits the strongest increases in the occurrence of extremely low snow years in response to global warming," Diffenbaugh explained in a story posted by the Stanford Woods Institute for the Environment. This phenomenon also will be accompanied by low snow accumulation. "It also exhibits some of the strongest decreases in runoff that occurs during the growing season." Diffenbaugh is a center fellow and assistant professor in Stanford's Department of Environmental Earth System Science.

The researchers used climate modeling techniques that integrated predicted future data using past data on average and extreme rates of precipitation, accumulation and runoff from 1976 to 2005. The researchers found that continued emissions of greenhouse gases such as carbon dioxide will result in “substantially” reduced snowpack during the next few decades so that low snow years could become the new normal (more than 80 percent of the time) by 2070 in the Western U.S., Alpine Europe, Central Asia and downstream of the Himalayas and Tibetan Plateau.

"Our results suggest that global warming will put increasing pressure on both flood control in the cold season and water availability in the dry season, and that these changes are likely to occur in some of the most densely populated and water-stressed areas of the planet," Diffenbaugh said.

Hydroelectric production, recreation industries dependent on snow and water, and ecosystems also could suffer, the researchers said.