Journal of Agriculture and Ecology Research International

Nigeria ranked among the world's four leading cocoa producers in 2021, with estimated output of between 250,000 and 300,000 metric tonnes, which contributed significantly to the country's non-oil export earnings. The southern states of Ondo, Cross River, Osun, Ekiti, Edo and Oyo are the main production areas. However, the sector has faced challenges such as low productivity, ageing trees and declining yields relative to those of regional peers. Among the effects of climate change experienced by Nigerian cocoa farmers are irregular rainfall, prolonged dry periods and greater pest and disease pressure on cocoa trees. These pressures have contributed to lower yields and deterioration in bean quality. Multiple linear regression was employed to identify climatic variables showing significant associations with cocoa yield. To investigate climate-related changes in cocoa production in the study area, downscaled outputs from six global circulation models (GCMs) were used. Climate and crop-yield simulations covered three periods: 1976–2005 (historical), 2021–2050 (mid-term) and 2071–2100 (long-term), under the RCP 4.5 emissions scenario. Fig. 5 illustrates the projected future changes in cocoa yield under RCP 4.5. For the study area, the GCM ensemble indicated annual yield reductions of 13,696 tonnes/year by 2050 and 20,004 tonnes/year by 2100. If these ensemble projections materialise, the resulting losses are estimated at approximately US$60,947,200 in 2050 and US$89,017,800 in 2100, respectively, on the assumption of a cocoa price of US$4,450 per tonne. Farmers should implement effective adaptation measures to limit the effects of future climate change on cocoa yield, with necessary inputs, including fungicides and pesticides, supplied to control cocoa black pod disease.