Page 190 - Climate Change and Food Systems

climate change and food systems: global assessments and implications for food security and trade
table 10
Change (%) in productivity, East Africa, 2010-2050, IMPACT model
Crop
No Climate Change
CSIRO A1B
MIROC A1B
CSIRO B1
MIROC B1
Cassava 54.7
Groundnuts 12.9
Maize 54.0
Millet 137.7
Rice 120.1
Sorghum 77.4
Sweet potatoes 161.3 and yams
Wheat 128.6
46.1
15.8
51.1
139.9
136.6
83.0
145.0
119.1
51.4 53.0 47.7
23.5 16.5 21.6
73.5 54.7 62.7
163.8 134.4 147.0
140.3 136.5 137.4
111.6 75.5 90.7
188.2 162.9 179.2
127.2 123.3 118.9
affected by climate change to increase in yield sufficiently well to have higher yields than without climate change. We would not expect this to be universally true – it would be unrealistic to expect that all farmers across the globe would be able to increase their yields to that degree in response to a price rise. But in Africa, where fertilizer use is low, it is plausible that a significant and sustained price rise could lead to farmers spending more on inputs such as fertilizer, leading to a rise in productivity.
In Table 10, productivity is projected to be higher in East Africa under climate change for groundnuts, maize, millet, rice, sorghum, and sweet potatoes and yams; however, climate change is anticipated to have a negative impact on cassava and wheat.
Table 11 shows the same type of results found in Table 10, except the projections are for Southern Africa. Millet is anticipated to have by far the largest productivity gains between 2010 and 2050, increasing by almost 250 percent. This is followed, in a distant second place, by cotton, which is projected to increase by more than 150 percent. Cassava is projected to have the lowest productivity gains among the crops for Southern Africa.
Source: Based on analysis conducted for Nelson et al. (2010) Note: Values are for the baseline economic-demographic scenario
4.3 All crops
Table 10 summarizes the productivity changes for a number of crops analysed for East Africa, based on the IMPACT model. It includes the no climate change scenario as well as four climate change scenarios.
The highest productivity gains were observed for sweet potatoes and yams, with more than a 160 percent increase expected between 2010 and 2050 (Table 10). This is followed by millet and rice. The lowest productivity gains are anticipated for groundnuts, followed by cassava and maize.
Averaging the results across climate models,
it appears that productivity for many crops in East Africa will be higher with climate change than without. This is not attributable to direct impacts of climate on yields, at least not in some of the cases. The direct impacts of climate change on some crops in East Africa are presented in Table 6.
On average, climate change across the globe will have negative effects on productivity, which will drive prices higher (Table 9). In response to the higher prices, farmers will endeavor to increase productivity – for example, through increased
use of fertilizers. This second-order effect will
then lead to some crops that were adversely
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