Global lake tipping vulnerability under sustained agricultural exposure

Intensive agriculture drives lake eutrophication, degrading water quality and biodiversity through harmful algal blooms, hypoxia, and costly regime shifts. It remains unclear whether agriculture triggers sudden change through expansion or instead accumulates vulnerability under long-standing land cover. Here we combine trophic state and nearshore land cover for 859 lakes worldwide to detect 125 abrupt, persistent tipping events from 2003 to 2022. We then use interpretable models to separate chronic agricultural exposure from rapid expansion, and compare simple driver-based forecasts with classical early warning signals. Near-term tipping risk is dominated by a lake’s baseline trophic state and its long-term surrounding cropland; small increases above that baseline raise the 12-month tipping risk by 16%, whereas early warning signals add little predictive power. These findings show that sustained agricultural pressure narrows the safe operating space for freshwater ecosystems and provide a versatile framework for managing other vulnerable social-ecological systems. Lakes tip into degraded states mainly because of what already surrounds them, not new developments. Chronic agricultural exposure and baseline water quality globally predict abrupt shifts better than early warning signals.