Vertical Atmospheric Moisture Change Across Global Hydroclimatic Regimes During the Past 50 Years

The vertical structure of atmospheric moisture is important for understanding land–atmosphere interactions, energy exchange, and the hydrological cycle. However, how thermodynamic moistening potential is expressed in observed specific-humidity changes across the troposphere remains insufficiently understood. Here, we analyse monthly mean temperature and specific humidity from ERA5 for 1979–2025 across 37 pressure levels and five hydroclimatic regimes. We quantify the thermodynamic component using Clausius–Clapeyron (C–C) scaling and diagnose the remaining non-thermodynamic residual, with MERRA-2 and ERA5-Land used to assess consistency. Terrestrial atmospheric moistening exhibits pronounced vertical variations. The thermodynamic component remains positive across the analysed levels but decreases substantially with height, from approximately 0.22–0.34 g kg⁻¹ decade⁻¹ at 1000 hPa to 0.002–0.06 g kg⁻¹ decade⁻¹ at 500 hPa and near zero at 250 hPa. In the lower troposphere, negative residuals (approximately − 0.30 to − 0.17 g kg⁻¹ decade⁻¹) substantially offset the thermodynamic component. The relative magnitude of the thermodynamic component increases toward 500 hPa, as indicated by CR values rising from 0.05–0.46 at 1000 hPa to 0.69–1.05 at 500 hPa, before becoming less distinct near 250 hPa (− 0.12 to 0.34). Hydroclimatic differences reflect variations in the extent to which the residual offsets thermodynamic moistening potential. These results show that terrestrial atmospheric moisture change is not a vertically uniform response to warming. Instead, the realized specific-humidity response depends on both the thermodynamic moistening potential and its height- and regime-dependent offset by the residual. This framework provides vertically resolved constraints for evaluating atmospheric humidity changes in climate models and motivates further investigation of the physical processes underlying the residual.