Hydrological response to climate variability, climate change, and climate extreme in the USA: climate model evaluation and projections

Water resources are sensitive to climate variability and change; predictions of seasonal to interannual climate variations and projections of long-term climate trends can provide significant values in managing water resources. This study examines the control (1975-1995) and future (19952100) climate simulated by a global climate model (GCM) and a regional climate simulation driven by the GCM control simulation for the USA. Comparison of the regional climate simulation with observations across 13 subregions showed that the simulation captured the seasonality and the distributions of precipitation rate quite well. The GCM control and climate change simulations showed that, as a result of a 1% increase in greenhouse gas concentrations per year, there will be a warming of 2-3 degrees C across the USA from 2000 to 2100. Although precipitation is not projected to change during this century, the warming trend will increase evapotranspiration to reduce annual basin mean runoff over five subregions along the coastal and south-central USA.