Climate-Driven Changing Groundwater Depth across North America

Groundwater provides a critical freshwater resource for agriculture, industry, and drinking water across North America. However, the long-term impacts of climate variability and change on groundwater availability remain poorly constrained at continental scales. Here, we evaluate how changing climate variability impacts North American groundwater table depths under three different future climate scenarios. We use the Water Table Model (WTM), a large-scale, physically based hydrological model, to simulate depth to water table at an annual scale from 1800 to 2100 CE. The model is forced by changing precipitation and evapotranspiration based on climate simulations and data from TraCE-21ka (past), CMIP6 (historical and future), and Terraclimate (present). Model results for the historical period (1800–2015) are evaluated against available lake, wetland, and groundwater well observations. Based on this, we find patterns of historical groundwater variability across North America. We then quantify spatial and temporal changes in depth to groundwater and identify regions of long-term groundwater stability, rise, or decline in response to climate forcing under three future scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5). Our results reveal strong regional heterogeneity, with relatively stable or rising groundwater levels in humid and high-latitude regions, in contrast to persistent declines in arid and semi-arid zones. Future groundwater availability depends strongly on the emission scenario simulated, highlighting increasing climate-driven groundwater vulnerability across large parts of North America. This work provides a novel, annually resolved, continental scale assessment of climate impacts on groundwater availability and offers valuable insights for large-scale water balance studies, drought assessment, and sustainable groundwater management under a changing climate.