Toward assessing NARCCAP regional climate model credibility for the North American Monsoon: Future climate simulations

The focus is on changes in precipitation and the processes driving the projected changes from the regional climate simulations and their driving coupled atmosphere--ocean global climate models.

The effect of known biases on the projections is also examined. Overall, there is strong ensemble agreement for a large decrease in precipitation during the monsoon season; however, this agreement and the magnitude of the ensemble-mean change is likely deceiving, as the greatest decreases are produced by the simulations that are the most biased in the baseline/current climate. Furthermore, some of the greatest decreases in precipitation are being driven by changes in processes/phenomena that are less credible (e.g., changes in El Niño-Southern Oscillation, when it is initially not simulated well).