Assessment of Regional Climate Change and Development of Climate Adaptation Decision Aids in the Southwestern United States

Over the next 10-50 years, policy makers in the southwestern United States are faced with complex planning and policy issues associated with increasing water and energy demand as a result of warmer temperatures and reduced availability of water, compounded by continued rapid population growth and economic development. This study uses a top-down, end-to-end approach consisting of dynamical downscaling, a novel bias-correction technique, and custom-developed decision-aid tools to assess regional climate changes in the Southwest and to derive decision aids that are based on direct communication with the planners at four military installations in the region. Dynamical downscaling is performed with the Weather Research and Forecasting model driven by the National Centers for Environmental Prediction reanalysis and the Max Planck Institute for Meteorology's ECHAM5 general circulation model for two time periods: current (2000s) and future (2030s). A unique two-stage bias correction is developed to adjust current and future hourly temperature and precipitation to be consistent with historical reference data. The authors' assessment of regional climate change, which is based on downscaled bias-corrected fields, points to a dryer and warmer future climate in the Southwest. The energy-usage modeling produced a statistically significant increase in natural gas consumption and a possible decrease in electricity usage in two military installations in Colorado, which is a direct consequence of decrease/increase in heating/cooling degree-days resulting from warmer temperatures in the future. In addition, the results indicate an increasing number of oppressive heat days in the future, which may impact long-term planning practices with respect to heat-stress control and heat-casualty management.