Projection of the global monsoon (GM) system is essential for water resource management, food security, and policymaking. Here we investigate projected changes in global monsoon area (GMA) and global monsoon intensity (GMI) with specific global warming levels, using two datasets of large-ensemble simulations. Both datasets project quasi-linear increases in GMA and GMI with global warming. The GMI over Northern-Hemisphere continents is consistently enhanced, while the GMI over Southern-Hemisphere continents are dominated by opposite changes in the GMI over South America. In addition, both datasets show enhanced monsoon intensity over most parts of regional monsoon domains, except for the North American monsoon. The different changes of the North American monsoon are up on projected temperature differences between the equatorial eastern Pacific and the tropical Atlantic. Moisture budget shows that the thermodynamic component always makes a large positive contribution to the increase in monsoon precipitation, while evaporation has a smaller positive contribution, except for the East Asian monsoon. The contribution of the dynamic component shows large differences for different regional monsoons. Therefore, the different changes in regional monsoon precipitation are mainly caused by the dynamic component.

Based on the observational dataset SA-OBS and model outputs from the Community Earth System Model Large Ensemble project, this study investigates heatwaves in Southeast Asia in the current and future warmer climate. A heatwave is detected when the daily maximum temperature exceeds the 90th percentile threshold at each grid for at least three consecutive days. Three characteristics describing the frequency, duration, and amplitude of heatwaves are examined, including the sum of heatwave days per year (HWF) satisfying the heatwave definition, the length of the longest yearly heatwave event (HWD), and the hottest amplitude of the hottest yearly heatwave event (HWA). Results indicate that increased global warming is associated with substantial changes in heatwave characteristics over Southeast Asia, with more frequent heatwaves, longer heatwave duration, and higher extreme temperatures. The increase in HWA has a linear growth against global warming levels with distinct regional differences between the Maritime Continent and the Indochina Peninsula due to their different heat content of lower atmospheric boundaries. In contrast, those in HWF and HWD have nonlinear growth characteristics. The projected warmer future tends to be associated with a higher risk ratio value with the occurrence of rarer extreme heatwaves relative to the current climate. These results reiterate the potential risks of extreme regional heatwaves if global warming is unrestricted.