2004: Effects of climate change on the hydrology and water resources of the Colorado River basin

was used to assess potential effects of climate change on the hydrology and water resources of the Colorado River Basin based on three climate conditions: an ensemble of three 105 year transient simulations based on business as usual (BAU) global greenhouse gas emissions, a control run based on static 1995 greenhouse gas concentrations, and historic conditions. Transient monthly temperature and precipitation sequences for the Colorado River basin were extracted from the climate model simulations using a statistical bias correction and downscaling method, and were used to drive the Variable Infiltration Capacity (VIC) macroscale hydrology to produce streamflow sequences. Results for the BAU scenarios were summarized into Periods 1, 2, and 3 (2010 – 2039, 2040- 2069, 2070 – 2098). Average annual temperature changes for the Colorado River basin were 0.5 °C warmer for control relative to historical, and 1.0, 1.7, and 2.4 °C warmer for Periods 1-3, respectively, relative to historical. Basin-average annual precipitation for the control climate was slightly (1%) less than historical, and 3, 6, and 3 % less than historical for future Periods 1-3. Annual runoff in the control run was about 10 % lower than for historical conditions, and 14, 18, and 17 % less for Periods 1-3, respectively. Higher wintertime temperatures also caused peak runoff to occur about one month earlier. Analysis of VIC simulated historic, control, and probable future flows with a wate