Slide 23: The experiment design
Now we apply a climate experiment on top of the pattern with no climate change. The 'minimum experiment' is a high change and low change scenario (A2 and B2), and two different climate change models, chosen from the about 12 available from the IPCC Data Distribution Centre website because they behave rather differently over southern Africa. For purposes of this experiment, the upper estimate of environmental shift was provided by the Hadley A2 scenario (giving an increase in temperature of about 5 °C, and a reduction in average rainfall of approximately 6%), whilst the lower estimate of climate change was provided by the CCModel B2 scenario (an average increase of 2.2 °C and a decrease of 1.2% in average rainfall). In order to use these estimates, however, the outputs of these models had to be downscaled significantly, since at the scale of GCM outputs, the whole of South Africa falls within about 12 cells.