Projections of East Asian summer monsoon under 1.5°C and 2°C warming goals

Based on 1.5 degrees C and 2.0 degrees C warming experiments of Community Earth System Model, this study documents future changes in the East Asian summer monsoon (EASM) and associated monsoon precipitation. The model reproduces reasonably well the climatology of East Asian summer rainfall. All ensemble means show an increase in EASM intensity and associated precipitation over most parts of the East Asian region in 1.5 degrees C never-exceed (1.5degNE), 1.5 degrees C overshoot (1.5degOS), and 2.0 degrees C (2.0degNE) experiments. There is no significant difference in the future changes in EASM intensity, EASM precipitation, and its location among the three scenarios. A moisture budget analysis demonstrates that the increased precipitation over East Asia in three scenarios should be ascribed to the changes in evaporation, vertical motion, and humidity. The contributions of these three dominant terms increase sequentially under 1.5degNE, 1.5degOS, and 2degNE scenarios. However, the differences among the three scenarios are quite small in three dominant terms. Over East Asia, the contributions of evaporation and vertical motion are generally larger than that of humidity to the domain-averaged EASM rainfall in each scenario.