Tom Gleeson, Mark Olaf Cuthbert , Grant Ferguson, Debra Perrone

Groundwater is a crucial resource for current and future generations but is not being sustainably used in many parts of the world. The objective of this review is to provide a clear portrait of global-scale groundwater sustainability, systems and resources in the Anthropocene, in order to inspire a pivot towards more sustainable pathways. We examine groundwater from three different but related perspectives of sustainability science, natural resource governance and management, and Earth Systems science. We propose that groundwater sustainability can be defined with a direct link with observable data, governance and management as well as the crucial functions and services of groundwater. An Earth System approach highlights the connections between groundwater and the rest of the hydrosphere, biosphere, atmosphere and lithosphere, and how these connections are impacting, or impacted by, groundwater pumping. Regional differences in priorities, hydrology, politics, culture and economic contexts mean that different governance and management tools are important. But a global perspective can support higher level international policies in an increasingly globalised world, that require broader analysis of interconnections between regions and knowledge transfer between regions.
1. Groundwater is depleted or contaminated in some regions and ubiquitously distributed which, importantly, makes it broadly accessible, but also slow and invisible and therefore challenging to govern and manage.
2. Groundwater is the largest store of unfrozen freshwater on Earth and is heterogeneously connected to a number of Earth System processes on different timescales.
3. A coherent overarching framework of groundwater sustainability is more important for groundwater governance and management than the concepts of safe yield, renewability, depletion or stress.