The potential impacts of climate variability and change on water resources and food security are receiving growing attention especially in regions that face growing challenges meeting water demands for agricultural, domestic and environmental uses. Rainfed agriculture regions exhibit higher vulnerability to climate variability and change, where aquifer storage and food security are under stress. Little research has attempted to investigate the consequences of climate variability and change on water availability and social livelihoods jointly. Employing available data on precipitation, farm budget data, and aquifer characteristics, a dynamic nonlinear optimization framework that maximizes the economic likelihoods of irrigation activities and food security under several climatic assumptions is developed and applied for Barbados as a numerical example. Our framework accounts for technological adaptation measure, drip irrigation, with the context of variable yield and cost of water demand under governmental subsidy schemes. Results indicate significant negative impacts of climate variability, change, and double exposure on future water resources and food security. However, some climate assumptions provide opportunity for some food producers who respond positively to technological adaptation programs, while consumers could face the major negative consequences by experiencing higher food prices. Our findings provide policymakers and stakeholders a comprehensive tool for economically efficient and sustainably reliant policy design, implementation, and evaluation facing the potential climate variability and change impacts.