ASSESSMENT OF THE IMPACT OF CLIMATE CHANGE ON CROP YIELD IN BORNO STATE

ABSTRACT This study provides a comprehensive analysis of long-term climate indicators specifically rainfall and temperature and their influence on crop yields across seven Local Government Areas (LGAs) in Borno State, Nigeria (Biu, Ngala, Kukawa, Damboa, Hawul, Gwoza, and Monguno) over a 35-year period (1990–2024). The research aimed to quantify the direction of regional climate change and evaluate its impact on agricultural productivity within the vulnerable Sudano-Sahelian ecological zone. The methodology involved compiling climate variables from secondary sources and structured historical datasets, while crop yield information (for maize, millet, and sorghum) was sourced from available agricultural reports. Statistical trend analysis was employed to determine averages, variability, and long-term shifts. Key findings reveal substantial climatic variations. Mean annual rainfall across the LGAs varied widely, with Biu recording the highest long-term average (1,020 mm) and Ngala the lowest (640 mm). Overall, rainfall exhibited a consistent decreasing trend, averaging a loss of 6.2 mm annually, which was most pronounced between 2005 and 2020. Conversely, temperature analysis indicated a steady warming trend; the mean annual temperature rose from 27.1°C in the 1990s to 30.4°C by 2020–2024, an average increase of +0.11°C per year. Monguno and Kukawa experienced the highest temperatures (average 31.2°C), while Hawul remained the coolest (average 26.8°C). Crop-yield statistics directly reflected the impact of this climate variability. In drier LGAs like Ngala, Kukawa, and Damboa, major staple crops saw significant yield declines of 18–32%, attributed to unstable rainfall and high heat. In contrast, LGAs with relatively higher rainfall, such as Biu and Hawul, recorded smaller declines (5–12%). Correlation analysis confirmed a strong positive relationship between rainfall and yield (r = 0.72) and a strong negative relationship between temperature and yield (r = –0.65), solidifying the link between rising heat, erratic rainfall, and reduced crop productivity. The study concludes that climate variability has profoundly impacted agricultural output in the selected LGAs. The results highlight the urgent need for the implementation of climate-resilient strategies such as developing drought-tolerant crop varieties, improving water-harvesting systems, and adopting adaptive agronomic practices to enhance food security in Borno State.