Climate variability and change in mountain environments: some implications for water resources and water quality in the Sierra Nevada (USA).

This article introduces this special journal issue on climate change impacts on Sierra Nevada water resources and provides a critical summary of major findings and questions that remain open, representing future research opportunities. Some of these questions are long standing, while others emerge from the new research reported in the eight research papers in this special issue. Six of the papers study Eastern Sierra watersheds, which have been under-represented in the recent literature. One of those papers presents hydrologic projections for Owens Valley, benefiting from multi-decadal streamflow records made available by the Los Angeles Department of Water and Power for hydrologic model calibration. Taken together, the eight research papers present an image of localized climatic and hydrologic specificity that allows few region-wide conclusions. A source of uncertainty across these studies concerns the inability of the (statistically downscaled) global climate model results that were used to adequately project future changes in key processes including (among others) the precipitation distribution with altitude. Greater availability of regional climate model results in the future will provide research opportunities to project altitudinal shifts in snowfall and rainfall, with important implications to snowmelt timing, streamflow temperatures, and the Eastern Sierra's precipitation-shadow effect. [ABSTRACT FROM AUTHOR]