Global water cycle changes in a warming climate: Projection from CMIP6 multi-model ensemble mean

Understanding the response of the global hydrological cycle to anthropogenic warming is critical for advancing water resources management and mitigating hydrological risks. This study employs a multi-model ensemble from the Coupled Model Intercomparison Project Phase 6 (CMIP6) to quantify projected changes in key global hydrological components, including evaporation, precipitation, total column water vapor (TCWV), and ocean-to-land moisture transport, under medium-emission (SSP2–4.5) and high-emission (SSP5–8.5) scenarios. Our analysis demonstrates a robust and progressively intensifying hydrological cycle throughout the 21st century, with substantially stronger changes under SSP5–8.5. Relative to 1995–2014, TCWV increases by 5.5% (2021–2040) and 16.8% (2081–2100) under SSP2–4.5, and by 6.3% and 34.8% under SSP5–8.5. A pronounced land–ocean asymmetry emerges: land regions exhibit more pronounced changes than oceans, with increases in terrestrial precipitation approximately 1.10–1.40 times greater than the corresponding oceanic rates, indicating stronger land amplification. Ocean-to-land moisture transport rises by 6.2% under SSP2–4.5 and 13.5% under SSP5–8.5 by the end of the century, contributing significantly to enhanced land precipitation and highlighting the importance of atmospheric moisture redistribution in shaping continental water availability. This study consolidates the quantitative sensitivity of the global water cycle to emission pathways and provides critical insights to support climate adaptation strategies.