Quantifying the potential impacts of climate change on irrigation demand, crop yields, and green water scarcity in the New Jersey Coastal Plain

Climate change has significant implications for irrigated agriculture and global food security. Understanding how altered precipitation patterns and magnitudes, coupled with rising growing season temperatures, affect irrigation demand and crop production is a prerequisite for formulating effective water resources management strategies. This study evaluated the effects of near-term climate change (centered on 2035) on irrigation demand, green water scarcity, and row crop yields in a major agricultural watershed in southern New Jersey, USA. Downscaled precipitation and temperature from six General Circulation Models (GCMs) for two representative concentration pathways (RCP-4.5 and 8.5) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) were used to drive the Soil and Water Assessment Tool hydrological model. Temperature and precipitation increases resulted in greater surface runoff, lateral flow, groundwater recharge, and total streamflow. Seasonal ET for corn is projected to alter between −3.0 % to 0.5 %, with irrigation demand between −17 % to −1 %, and yield ranges between −4 % to +9 % depending on the GCMs in the RCP-4.5 scenario, with similar patterns projected by RCP-8.5 scenario. For soybean, the simulation also indicates a declining trend of ET and irrigation demand while increasing yield. Increasing yield for both crops is attributed to changes in agronomic management practices combined with genetically improved cultivars and higher soil fertility due to CO₂ fertilization. Green water scarcity analysis under future climate change for corn and soybean display a decreased soil moisture stress due to increased water use efficiency resulting from reduced stomatal conductance under elevated CO₂ concentration.