Long-term Analysis of Rainfall and Surface Air Temperature Trends and the Associated Impacts on Crop Yields in Tanzania

Abstract

This paper analyses long-term trends in annual rainfall and surface air temperature in Tanzania (1983–2023), and assesses their impacts on crop yields. It utilised satellite data from NASA's repository, including the Geospatial Interactive Online Visualization and Analysis Infrastructure and the Prediction of Worldwide Energy Resources. Results reveal spatial and temporal variations in both rainfall and temperature across the country. The paper identifies non- significant decreasing trends in annual rainfall in Kigoma (MK = -0.027, p = 0.82) and Kilombero (MK = -0.018, p = 0.88) over the study period. Even though the trends in areas such as Dodoma, Dar es Salaam, Geita, Same and Njombe suggest increased annual rainfall, they also exhibit many years with annual rainfall below average. Besides, the Granger causality test indicated that rainfall had a significant impact on the decrease in maize yields in Geita and Dodoma, on beans in Same, and on paddy in Dodoma. Conversely, the results revealed a significant increasing trend in annual temperature in Kilombero (MK = 0.36, p = 0.001), while Dodoma exhibited a statistically significant decreasing trend (MK = - 0.23, p = 0.003). Moreover, the results revealed a total of 22 years with annual temperature above average in Njombe; and other areas such Kigoma, Geita, Same and Kilombero exhibiting 19 years with annual temperature above average. The paper emphasizes the need for climate-resilient agricultural practices, improved weather monitoring systems, and the development of drought-resistant crops to mitigate the adverse effects of climate variability. The results also raise the need for integrating climate data into agricultural planning and policy to support sustainable food production, and ensure long-term food security in Tanzania.