Page 181 - Climate Change and Food Systems

chapter 5: climate change impact on key crops in africa: using crop models and general equilibrium models to bound the predictions
If climate opportunity areas are identified, further analysis need to be performed to determine any additional concerns about impacts on environmentally sensitive areas. Points to consider are a) strengthening protection for environmentally sensitive areas; and b) strengthening or clarifying property rights issues.
Southern Africa
Figure 8 shows areas where rainfed maize
is grown in Southern Africa. Much of the western portion of South Africa and all but the northernmost part of Namibia do not currently cultivate maize, but it is otherwise grown throughout most of the region.
Figure 9 shows yield change maps for rainfed maize for the areas of highest maize concentration in Southern Africa. Analysis across all the models indicates that yields will be adversely affected in most of South Africa, but the expected impacts are more positive than negative in Zambia and Zimbabwe.
The results from the ECHAM model appear to be more negative in their outlook than results for the other models – most notably in northern Mozambique, but also in South Africa.
figure 8
Rainfed maize areas for Southern Africa, 2000
< 1 ha
1 to 10 ha
10 to 30 ha
30 to 100 ha 100 to 500 ha 500 to 3 000 ha > 3 000 ha
Sources: SPAM (Spatial Production Allocation Model)
(You and Wood 2006; You, Wood, and Wood-Sichra 2006, 2009)
Note: ha = hectare
In both the ECHAM and MIROC models, areas will become unproductive in Botswana and Angola, and also in northern Namibia according to the ECHAM model.
Potential new areas that might become productive, which are found across all models, include parts of Lesotho and part of South Africa just northeast of Lesotho. These all appear to be elevated areas.
West Africa
Figure 10 shows estimated areas of rainfed maize for West Africa from the SPAM model. Most of the maize is grown south of the Sahel although it is not grown on the western coast of the region, except in and around Gambia.
Figure 11 shows productivity changes of rainfed maize resulting from the crop model analysis of the climate models. These results are focused on the areas of highest maize concentration in West Africa.
With the possible exception of the CNRM GCM, the models show productivity losses across the entire southern coastal area of West Africa (Figure 11). The maps in this Figure indicate some areas of yield increase across Burkina Faso and southern Mali, and a slight amount in northern Nigeria. Finally, there appears to be a band in the north of Sudano- Sahel zone (shown in red) in which cultivation of rainfed maize will probably cease to be feasible. It is likely that temperature increase will be the main driver of this change, making it too warm to cultivate maize.
3.2 All crops
East Africa
Table 6 presents productivity changes from climate change, based on the crop model analysis in East Africa. Computations were done using weighted averages and applying harvested areas of the respective crops from the SPAM model as weights.
Rainfed sorghum, wheat, and soybeans, along with irrigated rice, are unequivocal losers under
161