Global Warming Influence on Major Seasonal and Intra-seasonal Rainfall Indicators for Sustainable Cocoa Production in West-central Côte d'Ivoire

Abstract

Ivorian cocoa production, which still remains the driving force of the national economy today, despite the increasingly pronounced diversification of the State's resources, has long benefited from relatively favorable climatic conditions. However, since the 1970s, recurrent disruptions in key rainfall indicators for cocoa production have posed significant risks to the yields and incomes of many Ivorians who depend directly or indirectly on the agronomic performance of this speculation. Using a methodological approach based on descriptive statistical analysis, this study provides an understanding of the evolution of the main climatic factors involved in cocoa production in the Central West, which is one of the country's natural cocoa production basins. To carry out this task, daily rainfall data from Divo and Gagnoa, covering the period 1946-2015, were collected and processed. The results of the various statistical analyses indicate that the seasonal and intra-seasonal rainfall indicators in Gagnoa and Divo are generally declining after the break-up years detected in 1972 in Divo and 1966 in Gagnoa. After the breaks, the Useful Rainy Season (URS) starts later and the ends are earlier than before, which results in a shortening of the length of the URS and a reduction in the intra-seasonal rainfall totals of the two localities. Conversely, the maximum dry sequences during the URS show a slight increase after the break-up dates. The station of Gagnoa was less affected by the rainfall recession than that of Divo where the downward trend in seasonal and intra-seasonal rainfall events is more severe. This makes the Gagnoa region the one with the best rainfall capacities for cocoa production in the study area.