Cuthbert, M. O.Gleeson, TomBierkens, M. F. P.Ferguson, G.Taylor, R. G.2025-09-222025-09-222024Cuthbert, M.O., Gleeson, T., Bierkens, M.F.P. et al. Concerns regarding proposed groundwater Earth system boundary. Nature, 635, E4–E5 (2024). https://doi.org/10.1038/s41586-024-08082-9https://doi.org/10.1038/s41586-024-08082-9https://hdl.handle.net/1828/22788Groundwater, the largest store of accessible freshwater on Earth, is under increasing pressure as a resource1 and its over-exploitation can harm dependent ecosystems, increase the severity of hydrological drought, and cause land subsidence and salinization2. It is, therefore, a welcome development that groundwater has been explicitly incorporated in the endeavour to quantify safe and just Earth system boundaries (ESBs) in a recent article by Rockström et al.3. However, here we raise concerns about the proposed groundwater ESB, by showing how it is based on an incorrect conceptual understanding of groundwater system dynamics and nomenclature. The proposed boundary is thus potentially misleading, with important implications for assessing the global status of groundwater resources with regards to safe and just water management.enCC BY 4.0environmental impacthydrologyArticleSchool of Earth and Ocean SciencesDepartment of Civil Engineering