Comparisons of Historical and Projected Trends in Extreme Temperatures in CMIP5 and Observations over the U.S

Average temperatures over the past 50 years have risen more than 2°F in the United States. In addition, the frequency of extreme heat events is rising over much of the U.S. while the number of extreme cold events is decreasing. This study is aimed at analyzing the latest climate model results from CMIP5 (Coupled Model Intercomparison Project Phase 5) to that of observations to determine how well the various climate models represent the observed trends in extreme temperatures. We will also analyze the future projections for such extreme events under different emissions scenarios. The analyses include investigation of the days above 90°F, 95°F, and 100°F and cold waves below 32°F (how many freezing days). Multiple day events, e.g., those associated with heat waves and cold waves are also investigated. Changes in the frequency of extreme temperature events can have important implications on various societal sectors (e.g., energy production, agriculture, infrastructure) and on ecosystems.