The projected changes in planted area, yield per area, net exports/imports and priced for five major agricultural crops in South Africa were simulated using the projections of four Global Circulation Models (GCMs) under three socio-economic scenarios. The GCM runs were those undertaken for the IPCC fourth assessment report. They show consistent strong warming over the subcontinent, but disagree with respect to future precipitation, from slight wetting (particularly on the eastern side) to overall slight drying. The future crop yields were simulated using the DSSAT crop model suite. The planted area, commodity prices and net exports were simulated using the IMPACT global food trade model. The results indicate slightly rising to stable yields per unit area up to 2050, despite climate change, largely due to the inbuilt assumption of ongoing agronomic and genetic improvements. The planted area remains fairly constant in both location and size. As a result of increasing food demand, net exports decline (i.e. imports increase) substantially, and so do prices due to simultaneous increases in global demand. The effects on food security in South Africa, measured as average calorific intake per person and malnutrition in children under the age of five, depends more on the assumptions regarding population and GDP growth than on climate change, since the study assumes that local shortages will be balanced by increased imports, if they are affordable. Thus the vulnerability to food insecurity at family and national level increases in the future under all but the most optimistic development scenarios, and is exacerbated by climate change, especially through global-scale, market-related mechanisms. Policies to increase local agricultural production, decrease its climate sensitivity and facilitate access to international markets are indicated, along with efforts to reduce agricultural greenhouse gas emissions.
Paper submitted to the special issue
Food Security and Climate Change