Groundwater recharge is sensitive to changing long-term aridity

Sustainable groundwater use relies on adequate rates of groundwater recharge, which are expected to change with climate change. However, climate impacts on recharge remain uncertain due to a paucity of measurements of recharge trends globally. Here we leverage the relationship between climatic aridity and long-term recharge measurements at 5,237 locations globally to identify regions where recharge is most sensitive to changes in climatic aridity. Recharge is most sensitive to climate changes in regions where potential evapotranspiration slightly exceeds precipitation, meaning even modest aridification can substantially decrease groundwater recharge. Future climate-induced recharge changes are expected to be dominated by precipitation changes, whereby changes in groundwater recharge will be amplified relative to precipitation changes. Recharge is more sensitive to changes in aridity than global hydrological models suggest. Consequently, the effects of climatic changes on groundwater replenishment and their impacts on the sustainability of groundwater use by humans and ecosystems probably exceed previous predictions.