Dynamic adaptive capacity of coupled agriculture-water systems under Climate Change: Evidence from the Western United States

Climate change is intensifying water scarcity and increasing production risk in irrigated agriculture across arid and semi-arid areas. Understanding how coupled agriculture-water systems adapt over time is essential for effective water management and climate adaptation. Despite important advances in adaptive capacity research, relatively few studies provide long-run, multi-year empirical assessments that integrate agriculture and water systems with adaptive capacity to capture their co-evolution under persistent climate stress. This study addresses this gap by developing a Dynamic framework for the Adaptive Capacity Index (ACI) to assess long-run adaptation in coupled agriculture-water systems across western U.S. states over the period 1997–2022. Using a deductive approach informed by a comprehensive literature review and expert judgment, the framework integrates six key determinants and 21 indicators covering economic and financial, social, natural and infrastructure, cognitive and behavioral, institutional and governance, and technological capacities. The robustness of the ACI results was evaluated through sensitivity analyses of alternative weighting, normalization, and aggregation methods. Findings reveal substantial variation in adaptive capacity across the region, with ACI values ranging from 0.197 to 0.793. Most states show long-run increases in adaptive capacity, but the magnitude of growth varies substantially, ranging from approximately 29–233% across states between 1997 and 2022. Economic, social, cognitive, and technological capacities show strong upward trends, while institutional capacity shows substantial state-specific variation and divergence, and natural and infrastructure capacity remains volatile under hydroclimatic constraints. The findings demonstrate that adaptation in irrigated agriculture is temporally and spatially heterogeneous, shaped by interactions among water availability, infrastructure, governance, and technological change.