CLIMATE VARIABILITY AND YIELDS OF MAJOR STAPLE FOOD CROPS IN NORTHERN GHANA

Climate variability, the short-term fluctuations in average weather conditions and agriculture affect each other. Climate variability affects the agroecological and growing conditions of crops and livestock, and is recently believed to be the greatest impediment to the realisation of the first Millennium Development Goal of reducing poverty and food insecurity in arid and semi-arid regions of developing countries. Conversely, agriculture is a major contributor to climate variability and change by emitting greenhouse gases and reducing the agroecology\u2019s potential for carbon sequestration. What however, is the empirical evidence of this inter-dependence of climate variability and agriculture in Sub-Sahara Africa? In this paper, we provide some insight into the long run relationship between inter-annual variations in temperature and rainfall, and annual yields of the most important staple food crops in Northern Ghana. Applying pooled panel data of rainfall, temperature and yields of the selected crops from 1976 to 2010 to cointegration and Granger causality models, there is cogent evidence of cointegration between seasonal, total rainfall and crop yields; and causality from rainfall to crop yields in the Sudano-Guinea Savannah and Guinea Savannah zones of Northern Ghana. This suggests that inter-annual yields of the crops have been influenced by the total amounts of rainfall in the planting season. Temperature variability over the study period is however stationary, and is suspected to have minimal effect, if any, on crop yields. Overall, the results confirm the appropriateness of our attempt in modelling long-term relationships between the climate and crop yield variables.La variabilit\ue9 du climat, les fluctuations \ue0 court terme des conditions m\ue9t\ue9orologiques moyennes et l\u2019agriculture s\u2019affectent mutuellement. La variabilit\ue9 climatique affecte les conditions agro\ue9cologiques et les conditions de croissance des cultures ainsi que l\u2019\ue9levage, et serait le principal obstacle \ue0 la r\ue9alisation du premier objectif principal du \u2018Millennium Development Goal\u2019 pour la r\ue9duction de la pauvret\ue9 et l\u2019ins\ue9curit\ue9 alimentaire dans des r\ue9gions arides et semi arides des pays en d\ue9veloppement. Inversement, l\u2019agriculture contribue de fa\ue7on importante \ue0 la variabilit\ue9 climatique et changement par l\u2019\ue9mission des gaz \ue0 effet de serre et r\ue9duction du potentiel agro\ue9cologique pour la s\ue9questration du carbone. Ceci constitue une \ue9vidence empirique de l\u2019interd\ue9pendance de la variabilit\ue9 climatique et l\u2019agriculture en Afrique sub-saharienne. Cet article pr\ue9sente une relation \ue0 long terme entre les variations interannuelles de la temp\ue9rature et de la pluviom\ue9trie ainsi que les rendements annuels de la plupart des cultures de base dans le Nord du Ghana. L\u2019application d\u2019un ensemble des donn\ue9es pluviom\ue9triques, temp\ue9rature et rendements des cultures s\ue9lectionn\ue9es depuis 1976 \ue0 2O12 pour la co-int\ue9gration et simulation par le mod\ue8le de causalit\ue9 Granger, li ya une forte \ue9vidence de la co-int\ue9gration entre les saisons, la pluviom\ue9trie totale et les rendements des cultures, ainsi que la causalit\ue9 de la pluviom\ue9trie aux rendements des cultures dans les savanes soudano-Guin\ue9ennes et les savanes guin\ue9ennes du nord du Ghana. Ceci sugg\ue8re les rendements interannuels des cultures ont \ue9t\ue9 influenc\ue9 par les quantit\ue9s totales des pluies au cours de la saison culturale. La variabilit\ue9 de la temp\ue9rature pendant la p\ue9riode d\u2019\ue9tude est par ailleurs stationnaire, et aurait un effet minimal ou non sur les rendements des cultures. En somme, les r\ue9sultats confirment la pertinence de cette tentative de mod\ue9lisation des relations \ue0 long terme entre le climat et les variables du rendement des cultures