Climate Change, Agricultural Total Factor Productivity, and Long-Run Food Security in Nigeria: A Structural Modelling Approach

Climate change poses an existential threat to agricultural productivity and food security in Nigeria, where the agricultural sector supports over 70 percent of rural livelihoods and food availability is closely tied to domestic production outcomes. Existing climate impact studies for Nigeria predominantly rely on crop simulation models that do not account for farmer adaptation behaviour, market responses, or total factor productivity dynamics, leading to potentially biased projections. This study develops a structural model integrating a climate-modified agricultural production function with an endogenous adaptation decision model and a partial equilibrium food market module to project the long-run effects of climate change on Nigerian agricultural total factor productivity and food security indicators through 2050. The model is calibrated using historical total factor productivity estimates from state-level panel data and downscaled climate projections from three global circulation models under RCP4.5 and RCP8.5 emission scenarios. Baseline and adaptation-inclusive projections are compared for six geopolitical zone-level representative farming systems. Results indicate that under RCP8.5 without adaptation, national agricultural total factor productivity declines by 19 percent by 2050 relative to the no-climate-change baseline, with the largest losses in North East zone dryland systems. Endogenous adaptation, including variety switching, irrigation expansion, and enterprise diversification, reduces productivity losses to 9 percent under RCP4.5. Food insecurity rates increase by 8 to 22 percentage points depending on scenario and adaptive capacity assumptions. The study makes original contributions to integrated climate-agriculture-food security modelling for sub-Saharan Africa. Keywords: climate change, total factor productivity, food security, structural modelling, Nigeria 2050