FORECASTING THE EFFECT OF CLIMATE VARIABILITY ON YAM YIELD IN RAINFOREST AND GUINEA SAVANNAH AGRO-ECOLOGICAL ZONE OF NIGERIA

The study empirically established climate variability and forecast the effect of climate variability on yam yield in the guinea savannah and rainforest agro-ecological zone of Nigeria. Historic climate datasets were collected and analyze for a period of 120 years (1901– 2019) for the study area. Statistical methods were used to show variabilities in climate using Probability Density Function (PDF), trend analysis, and change points analysis. To establish the future effect of climate variability on yam yield in the rainforest and guinea savannah of Nigeria, the study adapts two climate forecasting scenarios (i.e., Representative Concentration Pathway (RCP) 4.5 and RCP 8.5). Comparison of thirty years (Between 1931-1960 and 1961-1990) mean rainfall shows a reduction (102.47mm/year (8.32%) in annual mean rainfall from 1232.29 mm/year to 1129.82 mm/year. The results of the simulation of the model shows that by the year 2050, the yam yield using RCP 4.5 forecast scenario will be 0.34mmt/ha and 0.21mmt/ha using RCP 8.5 forecast scenario. Over time (2030, 2040 and 2050) in the rainforest agro-ecological zone, yam yield will be negative using the two (RCP 4.5 and RCP 8.5) forecasting forcing scenario. From the result, yam will perform better in the guinea savannah than in the rainforest zone of Nigeria in the future. The result shows that there is inverse relationship between yam yield and rainfall and positive relationship between yam yield and temperature in Nigeria. Hence, the study recommended that all stakeholders should ensure policies formulation that will encourage comparative advantage of food crop production based on climate variability now and in the future in each agro-ecological zone of Nigeria.