Quantification of human contribution to soil moisture-based terrestrial aridity.

Area of Science:

• Earth and Environmental Sciences
• Climate Science
• Hydrology

Background:

• Spatiotemporal patterns of terrestrial aridity changes remain uncertain.
• Soil moisture is a key indicator of aridity.

Purpose of the Study:

• To analyze historical and project future changes in soil moisture-based terrestrial aridity.
• To attribute observed aridification to human forcings.
• To improve future projections using emergent constraints.

Main Methods:

• Calculation of Standardized Soil Moisture Index (SSI) from multi-source merged data.
• Detection and attribution analysis of human forcings on SSI trends.
• Application of emergent constraint methods for future projections under SSP5-8.5.

Main Results:

• Widespread drying observed in global midlatitudes (1971-2016).
• Wetting detected in northern subtropics and specific northern latitudes during spring.
• Human forcings, especially greenhouse gases, significantly influence SSI changes across different soil depths and seasons.
• Future projections indicate continued human influence and accelerated drying in shallower soil layers (0-10 cm).

Conclusions:

• Human activities are the predominant drivers of heterogeneous terrestrial aridification.
• Findings provide a scientific basis for enhanced drought and flood risk management strategies.
• Understanding soil moisture dynamics is crucial for climate change adaptation.