Projections of Future Moisture Storage over the Conterminous United States Using a Simple Water Balance Approach and Statistically Downscaled Temperature and Precipitation

Global climate model (GCM) projections of future temperature over North America show significant warming across the continent in all seasons. Precipitation projections are more variable, both among models and among seasons. Even in areas projected to experience increases in precipitation, important questions are 1) whether or not any increased precipitation will be sufficient to offset the increase in evapotranspiration in the future, warmer climate and 2) whether changes in precipitation type will cause mountain snowpacks will increase or decrease. Here we use statistically downscaled temperature and precipitation from multiple CMIP3 and CMIP5 models and scenarios as input to a water balance model to project future moisture storage (as soil moisture and snow) across the conterminous United States. Soil moisture represents the water available to native vegetation and crops while mountain snowpacks represent a critical water resource, especially in the western United States. Projected changes in moisture storage, therefore, give a better indication as to whether any region will experience wetter or drier conditions in the future than do temperature and/or precipitation changes alone.