Nonlinear Climate–Production Relationships in an Irrigation-Dominated System: A NARDL Analysis of Flood-Irrigated Rice

Climate change imposes severe constraints on global food security, yet evidence on how crops respond to climate change in irrigation-dominated systems remains limited compared with rainfed agriculture. Building on this gap, we investigated how asymmetric climate shocks influence rice production in a major irrigated setting, using Egypt’s Nile Delta as a case study. Drawing on annual data for 1961–2022, we estimated a nonlinear autoregressive distributed lag (NARDL) model in which harvested area, fertilizer use, and seasonal temperature and precipitation jointly determine rice output, with structural-break tests used to inform model specification and the historical interpretation of major water and agricultural policy reforms. Temperature and precipitation are decomposed into cumulative positive and negative partial sums to isolate the effects of warming versus cooling and of rainfall surpluses versus deficits. The results showed a stable long-run cointegrating relationship with pronounced asymmetries. Autumn temperature shocks were most strongly associated with production variation, with cooling shocks more damaging than warming shocks were beneficial, while precipitation effects were asymmetric in the opposite direction: production gains associated with above average rainfall years exceeded the losses associated with below average rainfall years, consistent with irrigation buffering rainfall shortfalls. This finding does not rule out drainage-related losses from extreme, short-duration rainfall events, which the annual precipitation total used here cannot separately identify. Land expansion and fertilizer intensification remain positively associated with rice output, yet they only partially offset climate-induced losses, underscoring the limits of input-based adaptation amid increasing climatic volatility. Overall, the findings suggest that irrigation systems face distinct climate risks often obscured in symmetric models, highlighting adaptation priorities in drainage and storage, sustainable use of marginal lands, and season-specific climate services for irrigated rice regions.