Future Mediterranean Summer Drying Across Models: Opposing Dynamic and Thermodynamic Constraints

Abstract

Coupled Model Intercomparison Project Phase 6 (CMIP6) models project drier Mediterranean summers under global warming, yet exhibit substantial inter‐model spread. Notably, models with stronger global‐mean warming produce little additional drying. We show that this muted sensitivity to warming levels arises from the offset between thermodynamically driven drying and reduced regional subsidence. Moreover, the uncertainty in the subsidence response dominates the overall hydroclimate uncertainty. The subsidence response is mainly mediated by dry enthalpy advection linked to changes in tropical monsoon heating. Specifically, stronger West African summer monsoon rainfall is associated with a larger interhemispheric warming contrast, particularly excess warming in the northern mid‐to‐high latitudes, while weaker South Asian summer monsoon rainfall is associated with excess warming in the eastern tropical Pacific. These findings clarify why models diverge under identical greenhouse gas forcing and highlight the central role of the regional pattern of surface warming.