Groundwater Variability Is Strongly Linked to Soil Temperature Across Global Aquifers
Groundwater plays a critical role in land‐atmosphere interactions by regulating soil moisture and surface energy fluxes, yet its contribution to land‐surface processes and heat extremes remains poorly quantified globally. Here, we combine observation‐based aquifer records with gridded groundwater table depth (GWD) model outputs (2000–2015) to assess how GWD annual fluctuations covary with soil moisture, evaporation, soil temperature, and heatwave frequency across 1,658 aquifers worldwide. Soil temperature shows the most frequently dominant correlation with GWD among statistically significant, robust relationships (37% of aquifers), followed by evaporation (28%), heatwave frequency (22%), and soil moisture (13%). Aquifers with declining GWD suggest different coupling patterns compared to stable aquifers, with more negative relationships between GWD and evaporation and positive associations between GWD and soil temperature. Our results highlight the importance of incorporating groundwater dynamics into assessments of climate extremes and land‐surface processes.