HANS-JÜRGEN BUSS, ERNST-AUGUST NUPPENAU
Justus-Liebig-Universität Giessen, Institute of Agricultural Policy and Market Research, Germany
Climate change is a fact. At least from a farmer's perspective declining annual precipitation and higher rainfall variability is a challenge for viable farming strategies in the semi-arid region in Southern Africa. In Central Namibia cattle and game farmers face rangeland degradation. Above all, bush encroachment leads to a severe loss of pasture production potential. A local farming system with respect to both the economic decision making and the responding dynamics to natural pasture dynamics was investigated with the use of ecological-economic models. Hereby innovative technologies like new bush control measures were considered. To predict agro-ecological response and future farm developments, three different rainfall scenarios have been simulated. Within the simulation model rainfall is a stochastically appearing input factor. Main results of climate change are more extreme rainfall events. Therefore generated rainfall scenarios are based on a reduced mean precipitation (10%, 20% and 30%) but at the same time increased standard deviations (again 10%, 20% and 30%). At a 10% rainfall scenario, farm development does not significantly change when compared with an extrapolation of the current precipitation. At the 20% (and 30%) rainfall scenario, the picture changes drastically. Farmers would face less biomass production and higher risk and uncertainty. This has an impact on optimal farming strategies. Due to risk and decreasing productivity, investments in rangelands (sustainable farming techniques) get less attractive. In particular, investments in bush control do not pay anymore. This is even true for the new application of controlled bush fires although this is a rather ``cheap'' tool. As a consequence bush encroachment increases as future returns become uncertain. In fact, at climate change beyond the ecological/economic threshold (at the 20% rainfall-scenario), an optimal farming strategy would rather be to extract ``the natural assets'' quickly. As further simulations have shown, actual faming strategies also depend on the degree of indebtedness, labour costs, interest rates etc.. All in all, profi-seeking farmers might amplify the natural impact of climate change. This would lead to a self-enforcing mechanism of degradation as being dependent on risk.
Keywords: Climate change, farming strategy, livestock, model, Southern Africa