Global groundwater dependent wetland dynamics affected by climate variability and groundwater extraction over the last recent decades

Groundwater-dependent wetlands (GDWs) are important ecosystems that are increasingly affected by climate change and groundwater abstraction. Despite their ecological importance, GDWs remain inadequately mapped and monitored at the global scale. This study presents the first spatially explicit and temporarily dynamic global assessment of GDWs extent using a high-resolution, physically based groundwater model. We apply thresholds of saturated area fractions and water table depths to simulate spatiotemporal dynamics of GDWs at a 5 arcminutes (~10 km) resolution and monthly time step from 1979 to 2019. Validation against the intersection of the Global Lakes and Wetlands Database (GLWD v2) and the global groundwater-dependent ecosystems in drylands map by Rohde et al. (2024) confirm that our modelled GDW locations show strong agreement with independent GDE reference data (precision = 0.91, recall = 0.6 and f1 = 0.7). Simulation results reveal persistent GDW loss in regions with intensive groundwater abstraction (e.g., USA Central Valley, North China Plain and parts of Australia), and moderate increases in GDW extent in the biomes Montane grassland & shrublands and Boreal Forest/taiga, driven by climate-induced recharge increases. Despite high interannual variability, the global GDW extent declined by about 3–4% over the past 40 years, equivalent to a loss of ~300,000 km 2 , around the size of Italy, with losses exceeding 20% in biomes in the Cape region of South Africa, and southwestern Australia. Additionally, we found a potential relationship between GDW extent and El Niño-Southern Oscillation (ENSO) events, with declines in GDW extent in the southern hemisphere during and after ENSO events. Our model framework and results fill a critical gap in understanding the dynamics of GDWs, providing an efficient tool for conservation planning, climate impact assessments and policy development aligned with the Ramsar convention, sustainable development goals (SDGs), as well as other global biodiversity goals.