344
G. A. Manful and Y. Opoku-Ankomah
in 2014 amounted to 558,800 metric tons, equivalent to 12.2% of African fertilizer
consumption and 2% of global fertilizer consumption (FAOSTAT 2019). The Fifth
Assessment Report of the IPCC confirms that climate change exacerbates prevailing
stress on water availability and agricultural systems, particularly in semi-arid environments of Africa, such as the northern parts of the Volta River Basin. Increasing
temperatures and changes in precipitation in the Volta Basin are very likely to reduce
cereal crop productivity, with strong adverse effects on food security (Niang et al.
2014). Crop growing periods in West Africa may decrease by an average of up to 20%
by 2050, resulting in cereal yield losses of 40% as well as cereal biomass losses for
livestock due to a decline in rainfall and frequent, long-lasting and intense droughts
(Niang et al. 2014).
In its Fifth Assessment Report, the IPCC projects increases in precipitation in
West Africa to increase millet and sorghum yields; however, projected temperature
increases greater than 2 °C (relative to the 1961–1990 baseline) are estimated to
counteract positive effects on the yields of millet and sorghum (for B1, A1B, and
A2 scenarios) (Niang et al. 2014). These adverse effects will be felt more strongly
in the savannah ecological zone than in the Sahel, with new millet and sorghum
varieties subject to greater adverse impacts compared to their traditional counterparts (Sultan et al. 2013). Cassava (Manihot esculenta) is very adaptable to relatively
marginal soils, high temperatures and erratic rainfall conditions compared to many
cereal crops, making tuberous root crop a better substitute for cereals as an adaptation
response to climate change under rain-fed agricultural conditions. For peanuts, both
positive and negative impacts have been projected by researchers under A2 and B2
scenarios. Suitable agro-climatic zones for growing economically important perennial crops such as cocoa and coffee are estimated to diminish significantly, largely as
a result of the effects of rising temperatures. Under an A2 scenario, by mid-century,
suitable agroclimatic zones that are currently classified as very good to good for
perennial crops may become marginal, and zones that are currently marginally suitable may become unsuitable. The report further concludes that crop growing periods
in West Africa may decrease by an average of 20% by 2050, causing a 40% decline
in cereal yields and a reduction in cereal biomass for livestock (Niang et al. 2014);
these findings have been largely confirmed by Zougmoré (2016). Detailed atmospheric modeling for the West African region shows that the onset of rainy season
will shift to later in the year, roughly from April to May (van de Giesen et al. 2010).
Since the end of the rainy season, as well as the total amount of rainfall, remain more
or less fixed, the rainy season is decreasing in duration, leading to reduced rain-fed
agriculture, the dominant mode of food production in the region. The IPCC Special
Report projects that warming of up to 2 °C could result in accumulated heatwave
duration up to three months; warming of up to 3 °C would lead to drastic reductions
in the maize crop in Africa (IPCC 2018).
Schroth et al. (2016) observed that within the Volta Basin, cocoa is now mostly
grown in climates that have a maximum of four consecutive dry months, defined
as less than 100 mm of rainfall per month; in Ghana and Ivory Coast, the northern
limit of the cocoa belt also coincides roughly with the 4 months of dry season. The
difference between rainfall and ETP during the driest quarter is projected to decrease
G. A. Manful and Y. Opoku-Ankomah
in 2014 amounted to 558,800 metric tons, equivalent to 12.2% of African fertilizer
consumption and 2% of global fertilizer consumption (FAOSTAT 2019). The Fifth
Assessment Report of the IPCC confirms that climate change exacerbates prevailing
stress on water availability and agricultural systems, particularly in semi-arid environments of Africa, such as the northern parts of the Volta River Basin. Increasing
temperatures and changes in precipitation in the Volta Basin are very likely to reduce
cereal crop productivity, with strong adverse effects on food security (Niang et al.
2014). Crop growing periods in West Africa may decrease by an average of up to 20%
by 2050, resulting in cereal yield losses of 40% as well as cereal biomass losses for
livestock due to a decline in rainfall and frequent, long-lasting and intense droughts
(Niang et al. 2014).
In its Fifth Assessment Report, the IPCC projects increases in precipitation in
West Africa to increase millet and sorghum yields; however, projected temperature
increases greater than 2 °C (relative to the 1961–1990 baseline) are estimated to
counteract positive effects on the yields of millet and sorghum (for B1, A1B, and
A2 scenarios) (Niang et al. 2014). These adverse effects will be felt more strongly
in the savannah ecological zone than in the Sahel, with new millet and sorghum
varieties subject to greater adverse impacts compared to their traditional counterparts (Sultan et al. 2013). Cassava (Manihot esculenta) is very adaptable to relatively
marginal soils, high temperatures and erratic rainfall conditions compared to many
cereal crops, making tuberous root crop a better substitute for cereals as an adaptation
response to climate change under rain-fed agricultural conditions. For peanuts, both
positive and negative impacts have been projected by researchers under A2 and B2
scenarios. Suitable agro-climatic zones for growing economically important perennial crops such as cocoa and coffee are estimated to diminish significantly, largely as
a result of the effects of rising temperatures. Under an A2 scenario, by mid-century,
suitable agroclimatic zones that are currently classified as very good to good for
perennial crops may become marginal, and zones that are currently marginally suitable may become unsuitable. The report further concludes that crop growing periods
in West Africa may decrease by an average of 20% by 2050, causing a 40% decline
in cereal yields and a reduction in cereal biomass for livestock (Niang et al. 2014);
these findings have been largely confirmed by Zougmoré (2016). Detailed atmospheric modeling for the West African region shows that the onset of rainy season
will shift to later in the year, roughly from April to May (van de Giesen et al. 2010).
Since the end of the rainy season, as well as the total amount of rainfall, remain more
or less fixed, the rainy season is decreasing in duration, leading to reduced rain-fed
agriculture, the dominant mode of food production in the region. The IPCC Special
Report projects that warming of up to 2 °C could result in accumulated heatwave
duration up to three months; warming of up to 3 °C would lead to drastic reductions
in the maize crop in Africa (IPCC 2018).
Schroth et al. (2016) observed that within the Volta Basin, cocoa is now mostly
grown in climates that have a maximum of four consecutive dry months, defined
as less than 100 mm of rainfall per month; in Ghana and Ivory Coast, the northern
limit of the cocoa belt also coincides roughly with the 4 months of dry season. The
difference between rainfall and ETP during the driest quarter is projected to decrease