Social tipping points in global groundwater management.

Groundwater is critical to global food security, environmental flows, and millions of rural livelihoods in the face of climate change 1 . Although a third of Earth's largest groundwater basins are being depleted by irrigated agriculture 2 , little is known about the conditions that lead resource users to comply with conservation policies. Here we developed an agent-based model 3,4 of irrigated agriculture rooted in principles of cooperation 5,6 and collective action 7 and grounded on the World Values Survey Wave 6 (n = 90,350). Simulations of three major aquifer systems facing unsustainable demands reveal tipping points where social norms towards groundwater conservation shift abruptly with small changes in cultural values and monitoring and enforcement provisions. These tipping points are amplified by group size and best invoked by engaging a minority of rule followers. Overall, we present a powerful tool for evaluating the contingency of regulatory compliance upon cultural, socioeconomic, institutional and physical conditions, and its susceptibility to change beyond thresholds. Managing these thresholds may help to avoid unsustainable groundwater development, reduce enforcement costs, better account for cultural diversity in transboundary aquifer management and increase community resilience to changes in regional climate. Although we focus on groundwater, our methods and findings apply broadly to other resource management issues.