Future greenhouse warming is expected to influence the characteristics of global monsoon systems. However, large regional uncertainties still remain. Here we use 16 Coupled Model Intercomparison Project Phase 6 (CMIP6) models to determine how the length of the summer rainy season and precipitation extremes over the Asian summer monsoon domain will change in response to greenhouse warming. Over East Asia the models simulate on average on the earlier onset and later retreat; whereas over India, the retreat will occur later. The model simulations also show an intensification of extreme rainfall events, as well as an increase of seasonal drought conditions. These results demonstrate the high volatility of the Asian summer monsoon systems and further highlight the need for improved water management strategies in this densely populated part of the world.Plain Language Summary Future climate change is expected to influence the characteristics of the global monsoon system. However, large regional uncertainties still remain. Using 16 Coupled Model Intercomparison Project Phase 6 models, we determine the impact of greenhouse warming on the length of the summer rainy season and precipitation extremes over the Asian subregional monsoon domains (East Asia, western North Pacific, India, and Indo-China Peninsula). Over East Asia the models simulate on average an earlier inception and a later termination of the summer rainy season, whereas over India, the termination will occur later. The model simulations also show an intensification of extreme rainfall events, as well as an increase of seasonal drought conditions. Our results demonstrate the high volatility of the Asian summer monsoon system and further highlight the need for improved water management strategies in this densely populated part of the world.

Future change in summertime rainfall under a warmer climate will impact the lives of more than two-thirds of the world’s population. However, the future changes in the duration of the rainy season affected by regional characteristics are not yet entirely understood. We try to understand changes in the length of the rainy season as well as the amounts of the future summertime precipitation, and the related processes over regional monsoon domains using phase six of the Coupled Model Intercomparison Project archive. Projections reveal extensions of the rainy season over the most of monsoon domains, except over the American monsoon. Enhancing the precipitation in the future climate has various increasing rates depending on the subregional monsoon, and it is mainly affected by changes in thermodynamic factors. This study promotes awareness for the risk of unforeseen future situations by showing regional changes in precipitation according to future scenarios.

<p><span>Future greenhouse warming is expected to influence the character of global monsoon systems. However, large regional uncertainties still remain. Here we use 16 CMIP6 models to determine how the length of the summer rainy season and precipitation extremes over the Asian summer monsoon domain will change in response to greenhouse warming. Over East Asia the models simulate on average on the earlier onset and later retreat; whereas over India, the retreat will occur later. The model simulations also show an intensification of extreme rainfall events, as well as an increase of seasonal drought conditions. These results demonstrate the high volatility of the Asian summer monsoon systems and further highlight the need for improved water management strategies in this densely-populated part of the world.</span></p>