USGCRP
Home 
Links to Images
Images from Our Changing Planet, FY 2003
Figure 3.2. Changes in cold season extreme precipitation and mean annual
snowpack based on simulations of current and mid-21st century climate
conditions |
| Search |
Updated
12 October, 2003
|
Images from
|
Figure 3.2
Changes in cold season extreme precipitation (left) and mean annual snowpack (right)
based on simulations of current and mid-21st century climate conditions
This figure shows the difference between three future (2040-2060) regional climate simulations based on the Penn State/National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) and a control simulation with concentrations of greenhouse gases kept constant at the 1995 level. Results show that, by the mid-21
st century, the projected average regional warming of 1-2.5oC would strongly affect snowpack in the western U.S. Along coastal mountains, reduction in annual snowpack is above 50 percent. Snowpack increases slightly over the Northern Rockies, because precipitation is found to increase while temperature remains mostly below freezing, even under these simulated future climate conditions. In addition to changes in mean temperature, precipitation, and snowpack, cold season extreme precipitation is projected to increase by 5-15 mm/day (15-20 percent) along the Cascades and Sierra Nevada ranges. Changes in snowpack and extreme precipitation suggest higher likelihood of wintertime flooding and reduced water supply in the summer. Such changes could have significant impacts on water resources in the western U.S. A pilot project is currently investigating the the potential for adapting to these changes by using alternative water management strategies in the Columbia River and Sacramento-San Joaquin Basins.The Accelerated Climate Prediction Initiative (ACPI) was funded by DOE to develop the scientific and computational infrastructures needed to carry through a full assessment of the possible effects of human-induced climate change. This information forms the scientific basis for showing how climate change might affect the U.S. and for developing strategies for adapting to such change. As part of the ACPI, this ensemble of global climate simulations was produced by NCAR, using the NCAR/DOE Parallel Climate Model (PCM). The simulations were initialized at 1995 using observed ocean conditions. Four independent simulations were obtained. Three were transient simulations of future climate conditions (1995-2100), driven by increasing greenhouse gas concentrations that followed the IPCC "business as usual" scenario. These simulations were compared to a control simulation. Two regional climate models were used to downscale the PCM control and future climate simulations. These downscaled results were then used to drive various process models to study mid-century effects of climate change on water resources in the western U.S.
[Credit: L. Ruby Leung, Pacific Northwest National Laboratory. More information on the ACPI pilot study is available at http://www.pnl.gov/ccpp/acpi.htm.]
|
