Implications of a range of climate scenarios for water resources in the Pacific Northwest

The Pacific Northwest's water resources are heavily dependent on snowmelt to transfer water from the wet winters to the dry summers, and are therefore sensitive to the snow-determining influences of climate variations and climate change. Anthropogenic climate change is expected to produce significant warming in the Northwest, and needs to be included in plans for future water resources. To quantify the responses of Northwest water resources to projected changes in both temperature and precipitation, we have implemented the Variable Infiltration Capacity (VIC) model at 1/8 degree resolution. We used projected changes in temperature and precipitation for the Pacific Northwest region from four climate models, and performed simulations with the VIC model by perturbing observed 20th century weather data. The resulting range gives better guidance to policymakers than a single climate-change scenario.