Impacts of groundwater level change on ecosystems and societies worldwide

Groundwater is vital to human and ecosystems, yet it is largely affected by anthropogenic activities, including groundwater extraction and climate change, which have modified groundwater processes and behaviour. This has led to changes in groundwater level long-term trends. Through a collaborative effort involving 47 countries distributed across a range of climatic, geographic, hydrogeological and socioeconomic contexts worldwide, we have collated updated groundwater level data from national monitoring networks. This unprecedented in-situ dataset provides a unique opportunity to conduct a harmonized assessment of groundwater level trends worldwide over the past 20 years. Based on a novel quantitative analysis, we identified regional patterns and hotspots. We conducted a targeted review, linking observed trends to their actual consequences, offering insights into who and what is affected by groundwater changes and how.  We show that almost one third of the groundwater levels trends are declining – thus reflecting overexploitation of groundwater – while groundwater levels are rising in 18% of wells – not always indicating a recovery but also the consequence of human impact on the environment. We show that both rising and falling groundwater levels have substantial impacts on water and food security, ecosystems, infrastructure and socioeconomic wellbeing. By linking global groundwater trends with their practical impacts, our work provides the foundation for evaluating whether the adverse impacts of groundwater use and human activities outweigh the benefits, supporting a more effective, evidence-based sustainable groundwater management. It highlights the need for broader international participation and data sharing to ensure continuous refinement of groundwater assessment. Understanding and analysing the impacts at different scales can support decision-making on which impacts are acceptable, which are not, thus supporting the estimation of sustainable groundwater extraction. The extent of the impacts of GWL changes in so many aspects of life underscores the urgent need to integrate and mainstream groundwater in development plans.