Soil moisture in the Anthropocene: a tipping component in planetary boundary transgressions

Abstract In the Anthropocene, soil moisture emerged as a critical tipping component in the stability of Earth’s systems. Within the planetary boundary framework, which defines safe operational limits for human activity to sustain the stability of the Earth system, soil moisture plays an essential role as a core component of the water cycle. It governs key ecohydrological processes, regulates land-atmosphere energy exchange, and supports carbon and water cycling, which are vital for climate resilience and biodiversity. This study explores global, regional, and river basin scale changes in soil moisture, hot spot regions of soil moisture change, and its multifaceted influence across several planetary boundaries, particularly those related to freshwater availability, land-system change, and climate regulation. Reanalysis and remote sensing evidence reveal significant declines in soil moisture across major global river basins, driven by intensifying climate change and land use transformations. These shifts signal increasing pressure from human activities on Earth system resilience and highlight the urgent need to integrate soil moisture into global sustainability assessments. Recognizing soil moisture as a dynamic and interconnected boundary variable is essential for enhancing environmental monitoring, maintaining ecological balance, informing policy interventions, and safeguarding the planet’s life-support systems in an era of accelerating change.