Vulnerability assessment of the maize and sorghum crops to climate change in Botswana

This study examines the sensitivity of maize and sorghum crops to global warming in Botswana, a country with arid climatic conditions and shortfalls in locally produced grain. The vulnerability of the maize and sorghum crops to climate change were studied using crop simulation models while climate change scenarios were generated from Global Circulation Models. Simulated yields indicated that rain-fed crop production under the observed climate was a small fraction of what could be produced under optimal conditions. The gap was attributed to both physical (especially lack of rain) and socio-economic constraints. Using the southern African core climate change scenario, simulated yields declined by 36% in the case of maize and 31% for sorghum in the sand veldt region. Yield reductions from the hard veldt region were in the order of 10% for both maize and sorghum. The growing season became shorter, the average reduction in days in the sand veldt region being 5 and 8 days for maize and sorghum respectively, and correspondingly, 3 and 4 days over the hard veldt region. The food security option currently followed in Botswana was found to be a good adaptive strategy under a changed climate.