A high resolution nested simulation of climate change for the western United States using CCM3 and MM5

A key goal of the climate research community is to detect and attribute climate change, using a combination of observations and numerical modeling of the climate system. The detection and attribution of climate change at the global scale provides confirmation of the effects of human activities on climate. However, global-scale detection and attribution provides very limited information regarding regional scale changes, whereas many policy decisions concerning the adaptation and response to climate change need to be made at the regional to local scales. Here we report high-resolution simulations of present and future climates in the western United States using the CCM3 global atmospheric model at T170 truncation in combination with the MM5 limited- domain model running at 9km resolution. As a result of a doubling of atmospheric CO2, we find significant shifts in wintertime precipitation patterns and warming.