Assessment of future changes in water availability and aridity

• Published in: Geophysical research letters Vol. 42; no. 13; pp. 5493 - 5499
• Main Authors: Greve, P., Seneviratne, S. I.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 16.07.2015; John Wiley & Sons, Inc; American Geophysical Union; John Wiley and Sons Inc
• Subjects: 21st century; Area; Aridity; Assessments; Atmospheric; Atmospheric precipitations; Atmospheric Processes; Availability; climate change; CMIP5; Driers; dry gets drier; dry gets drier, wet gets wetter; Drying; ENVIRONMENTAL SCIENCES; Evapotranspiration; Geodesy and Gravity; Global Change; Global Climate Models; Hydroclimatology; Hydrologic cycle; Hydrological cycle; Hydrological Cycles and Budgets; Hydrology; Land; Land area; Land/Atmosphere Interactions; Latitude; Mass Balance; Natural Hazards; Paleoceanography; Precipitation; Projection; Regions; Research Letter; Research Letters; Simplification; Uncertainty; Water availability; Water Cycles; wet gets wetter; Wetting; CMIP5; aridity; dry gets drier, wet gets wetter; climate change; water availability
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL064127

Substantial changes in the hydrological cycle are projected for the 21st century, but these projections are subject to major uncertainties. In this context, the “dry gets drier, wet gets wetter” (DDWW) paradigm is often used as a simplifying summary. However, recent studies cast doubt on the validity of the paradigm and also on applying the widely used P − E (precipitation − evapotranspiration) metric over global land surfaces. Here we show in a comprehensive CMIP5‐based assessment that projected changes in mean annual P − E are generally not significant, except for high‐latitude regions showing wetting conditions until the end of the 21st century. Significant increases in aridity do occur in many subtropical and also adjacent humid regions. However, combining both metrics still shows that approximately 70% of all land area will not experience significant changes. Based on these findings, we conclude that the DDWW paradigm is generally not confirmed for projected changes in most land areas. Key Points Future changes in water availability and aridity are assessed Underlying uncertainties are explicitly taken into account The “dry gets drier, wet gets wetter” paradigm is challenged