Model-based insights into temperature-driven declines in groundwater recharge under global warming in Michigan’s Lower Peninsula

Global warming alters temperature and precipitation patterns, producing complex impacts on groundwater recharge. To quantify these effects, rainfall–infiltration models integrating precipitation, snowmelt, runoff, soil moisture, and evapotranspiration were applied to Michigan’s Lower Peninsula from 1972 to 2041. Path analysis was used to distinguish the direct and indirect effects of temperature and rainfall on recharge. Results indicate that rising temperatures enhance evapotranspiration, which outweighs the benefits of increased rainfall, leading to a net decline in groundwater recharge. Average annual recharge is about 27 cm, decreasing by 0.96 cm per decade in the north and 4.12–4.33 cm per decade in the south. Temperature and rainfall together explain 61.9–78.7% of recharge variability, with 1 °C warming reducing recharge by 0.74–0.85 cm a⁻1. Overall, rainfall increases under global warming are insufficient to offset evapotranspiration-driven losses, underscoring the dominant thermal control on groundwater sustainability.