Intensification of summer mesoscale convective systems in East China under global warming.

Mesoscale Convective Systems (MCSs) are the primary drivers of extreme rainfall and flood hazards. Understanding their response to global warming is therefore important for improving climate projections and disaster risk reduction. In East China, however, evidence remains largely limited to case studies, and long-term projections of MCSs are scarce due to their poor representation in coarse-resolution climate models. Using convection-permitting model simulations with a pseudo-global warming approach, this study presents 22-summer projections of future MCSs over East China under the SSP5-8.5 scenario. Results show that future MCSs exhibit higher precipitation intensity and wider convective areas. Convective precipitation intensifies more than stratiform precipitation, indicating a transition toward more convection-dominated systems, accompanied by enhanced mid-level updrafts and super-Clausius-Clapeyron scaling of extreme rainfall. Increases in convective available potential energy (CAPE) and total column water vapor (TCWV) largely explain the intensification of maximum convective precipitation, with vertical zonal wind shear acting as a key dynamic modulator. The product of TCWV and vertical velocity is identified as an effective predictor of MCS peak precipitation. These findings imply heightened risks of intense rainfall from MCSs in East China and highlight the combined roles of thermodynamic and dynamic processes in shaping future MCSs.