Ocean Salinities Reveal Strong Global Water Cycle Intensification During 1950 to 2000

TLDR

Climate models predict that warming will make dry areas drier and wet areas wetter, but long‑term observations of rainfall and evaporation have not yet confirmed this trend. The study demonstrates that patterns in ocean salinity provide a clear fingerprint of an intensifying global water cycle. Observed global surface salinity changes over 50 years, together with model outputs, reveal an intensification rate of 8 ± 5 % per degree of surface warming—twice the rate projected by current models—and imply a 16–24 % increase in the water cycle under a 2–3 °C warming scenario.

Abstract

Fundamental thermodynamics and climate models suggest that dry regions will become drier and wet regions will become wetter in response to warming. Efforts to detect this long-term response in sparse surface observations of rainfall and evaporation remain ambiguous. We show that ocean salinity patterns express an identifiable fingerprint of an intensifying water cycle. Our 50-year observed global surface salinity changes, combined with changes from global climate models, present robust evidence of an intensified global water cycle at a rate of 8 ± 5% per degree of surface warming. This rate is double the response projected by current-generation climate models and suggests that a substantial (16 to 24%) intensification of the global water cycle will occur in a future 2° to 3° warmer world.