22
concern for food security and nutrition. While adaptation in the short- and mid-term
may help some areas to continue growing these crops, by the end of the century it is
estimated that over 30% of the area where maize is grown and over 60% of the area
where beans are grown would need to grow entirely different crops (Rippke et al.
2016).
Some crops are much more resilient than maize and beans to changes in climate.
In southern Africa, Ramirez-Villegas and Thornton (2015) showed that the suitable
area for beans decreased greatly and maize decreased slightly, whereas other
crops—banana, yam and pearl millet—increased in range. Similar results were
found in East Africa, where maize and beans are projected to experience major
decreases in suitable area, whereas cassava, groundnut, pearl millet and banana are
projected to increase. These more resilient crops could be promoted as replacement
options for areas that require adaptation.
Under climate change, pressures from pests, weeds and diseases are also expected
to increase. In the highland regions of East Africa, warming trends could lead to the
expansion of crop pests—such as the coffee berry borer—into previously coldlimited areas (Jaramillo et al. 2011). Threats to banana production could come from
range expansion of burrowing nematodes (Nicholls et al. 2008) and black leaf streak
disease. Striga weed, a major cause of cereal yield reduction in sub-Saharan Africa,
could become a more widespread problem because of changes in temperature, rainfall and seasonality (Niang et al. 2014). By contrast, climate change may reduce the
range of major cassava pests including whitefly, cassava mealybug, cassava brown
streak virus and cassava mosaic geminivirus (Jarvis et al. 2012). However, certain
areas of current cassava production—including Southeast Africa and Madagascar—
may see an increase in whiteflies, mites and mealybugs (Bellotti et al. 2012). In the
case of livestock, changes in temperature and rainfall could increase the suitability
of the main tick vector of East Coast fever across much of Southern Africa (Olwoch
et al. 2008).
2.4 Implications for Development
2.4.1 Adapting African Agriculture to Climate Change
African agriculture must adapt in order to ensure food and nutritional security.
Management adjustments and crop breeding will be critical in the short- and midterm, whereas at longer timescales planned transformations will likely be necessary
(Rippke et al. 2016; Rickards and Howden 2012). Farmers and agricultural service
providers—input suppliers, extension, financial services, safety net programs,
etc.—will need to become resilient to new climate variability.
Although there is uncertainty in future climate projections, we have a great deal
of solid information regarding how climate is already changing and the types of
impacts farmers will need to address into the future. It is certain that temperatures
E. Girvetz et al.
concern for food security and nutrition. While adaptation in the short- and mid-term
may help some areas to continue growing these crops, by the end of the century it is
estimated that over 30% of the area where maize is grown and over 60% of the area
where beans are grown would need to grow entirely different crops (Rippke et al.
2016).
Some crops are much more resilient than maize and beans to changes in climate.
In southern Africa, Ramirez-Villegas and Thornton (2015) showed that the suitable
area for beans decreased greatly and maize decreased slightly, whereas other
crops—banana, yam and pearl millet—increased in range. Similar results were
found in East Africa, where maize and beans are projected to experience major
decreases in suitable area, whereas cassava, groundnut, pearl millet and banana are
projected to increase. These more resilient crops could be promoted as replacement
options for areas that require adaptation.
Under climate change, pressures from pests, weeds and diseases are also expected
to increase. In the highland regions of East Africa, warming trends could lead to the
expansion of crop pests—such as the coffee berry borer—into previously coldlimited areas (Jaramillo et al. 2011). Threats to banana production could come from
range expansion of burrowing nematodes (Nicholls et al. 2008) and black leaf streak
disease. Striga weed, a major cause of cereal yield reduction in sub-Saharan Africa,
could become a more widespread problem because of changes in temperature, rainfall and seasonality (Niang et al. 2014). By contrast, climate change may reduce the
range of major cassava pests including whitefly, cassava mealybug, cassava brown
streak virus and cassava mosaic geminivirus (Jarvis et al. 2012). However, certain
areas of current cassava production—including Southeast Africa and Madagascar—
may see an increase in whiteflies, mites and mealybugs (Bellotti et al. 2012). In the
case of livestock, changes in temperature and rainfall could increase the suitability
of the main tick vector of East Coast fever across much of Southern Africa (Olwoch
et al. 2008).
2.4 Implications for Development
2.4.1 Adapting African Agriculture to Climate Change
African agriculture must adapt in order to ensure food and nutritional security.
Management adjustments and crop breeding will be critical in the short- and midterm, whereas at longer timescales planned transformations will likely be necessary
(Rippke et al. 2016; Rickards and Howden 2012). Farmers and agricultural service
providers—input suppliers, extension, financial services, safety net programs,
etc.—will need to become resilient to new climate variability.
Although there is uncertainty in future climate projections, we have a great deal
of solid information regarding how climate is already changing and the types of
impacts farmers will need to address into the future. It is certain that temperatures
E. Girvetz et al.