The past and future climatic suitability of arabica coffee (Coffea arabica L.) in East Africa.

Abstract

Coffea arabica (arabica coffee) is a socially and economically important commodity crop in countries throughout East Africa. The distribution and productivity of coffee is dependent upon climate, the environment, and socio-economic factors. Previous studies involving a wide range of plant and animal species have shown that climatic changes affect species distributions. Global circulation models suggest climatic change over the next century, and predict warmer temperatures, and increasingly variable precipitation in East Africa. Whilst several studies have modelled the potential impacts of future climatic change on global food crops, there is a lack of information on the potential suitability and likely productivity of arabica coffee in East Africa. Using information from previous studies this study suggested optimal and tolerable climatic thresholds of mean annual temperature, and total precipitation, for arabica coffee. Using a bioclimatic envelope model, the past, present, and future areas of climatic suitability of arabica coffee were determined in eight East African countries. A declining trend in the number of optimal and tolerable locations was identified over the past forty years in all eight countries. Using modelled future temperatures and precipitation from a range of global circulation models, it was shown that the number of optimal coffee locations will continue to decline over the next century. The number of future tolerable locations did not decline greatly, and increased in some regions. Correlating seasonal and mean annual temperatures and precipitation, with annual country-level yields from the past forty years, showed that some of the variance in yield could be explained by changes in temperature and precipitation. Socio-economic factors are of importance in determining arabica coffee productivity and the negative effects of future climatic changes may be mitigated through a range of management options.