1. Agriculture and Development in Africa
In sub-Saharan Africa (SSA), agricultural growth and productivity and economic development are intricately linked. Agriculture directly contributes to up to 34% of the gross domestic product and 64% of employment (Osbahr et al., 2008). Since 1987, agricultural growth in states in SSA has largely been modest, whereas the poverty rate has remained high (AGRA, 2014). This is particularly concerning given that, by the year 2050, the population of Africa is expected to double to 2.3 billion (PDDESA-UN, 2013), meaning there will be considerably more people to feed and livelihoods to sustain. For agriculture to meet this growing food and livelihoods demand, and needs from agribusiness in SSA, production will be required to increase from current levels at a rate twice that of the global average until 2055 (FAO, 2003).
Growth in agriculture is at least two to four times more effective in reducing poverty than in other sectors (Comenetz and Caviedes, 2002). Therefore, there is no doubt that improvement in the agricultural sectors in SSA will have positive implications on food security, livelihoods, and state economies. In recognition of the importance of agriculture in African economies, the Comprehensive Africa Agriculture Development Programme (CAADP) was initiated by African states through the Maputo Declaration in 2003. CAADP signatories committed to ensuring sustained growth of at least 6% per year in agriculture by allocating at least 10% of their national budget to agriculture (NEPAD-CAADP, 2010). This has been followed up more recently by the Malabo Declaration of 2014, which reaffirms African states’ commitment to the Maputo Declaration.
Despite the good intentions of African states regarding growth in agriculture as espoused through the Maputo and Malabo declarations, a plethora of factors has placed immense challenges on the agricultural sector and economic development in SSA; these include political instability, insecure land rights, disease burden (e.g., HIV/AIDS and malaria), poor access to markets, and fluctuating world market prices (World Bank, 2009). Large-scale land investments are also dispossessing smallholder crop farmers and pastoralists of their land rights and threatening their livelihoods (De Schutter, 2011).
To add to these challenges, agriculture in SSA (crop production, livestock rearing, fisheries, and forestry) has historically had to contend with the vagaries of climate. Climate change and variability has exposed agriculture in Africa to additional stress, largely because SSA’s agricultural systems rely heavily on the climate (AGRA, 2014). The largest contributors to growth in agriculture in SSA are smallholder crop farmers and livestock keepers operating largely under marginal, dryland conditions, contributing to more than 60% of agricultural production in countries like Zimbabwe, Zambia, and Malawi (World Bank, 2009). Climate change and variability, coupled with the marginal nature of the agricultural systems and the socioeconomic vulnerability of the ill-resourced farmers that operate in them, presents one of the leading challenges to economic development in Africa in the 21st century.
2. Climate Change and Variability and Agriculture in Sub-Saharan Africa
The fifth assessment report of the Intergovernmental Panel on Climate Change shows that the climate has been changing in SSA over the past century (IPCC, 2014). There is evidence of warming throughout the past century, with temperatures rising by 0.5–2°C. Rainfall trends in SSA since the early 1900s vary considerably, with trends of decrease in some parts of West Africa, increase in large parts of Southeast Africa, and greatly varying trends of both increase and decrease in East Africa in time and space over the past 30–60 years. Despite data challenges that make it difficult to ascertain historical climatic trends across SSA, there is a satisfactory set of evidence to suggest that there is justification for the increasing importance placed on climate change and variability and the risks it poses on productive sectors like agriculture and by extension the economies of SSA states.
Climate variability is highly reflected in the varying levels of production over time in African dryland agricultural systems. For example, a strong relationship exists between climate and crop yields, with climate variability explaining 30%–75% of all crop yield variation on the continent (Ray et al., 2015). Driven by phenomena such as the El Niño Southern Oscillation (ENSO) and monsoons, the regional seasonal climate continues to play an important role in agricultural productivity, livelihoods, and economies of SSA states. Seasonal rainfall variability in selected SSA states increases disproportionally from wetter locations to the drier semiarid parts. This is particularly concerning for SSA agriculture because the larger portion of the region receives rainfall below 1000 mm per year and is where most dryland crop and livestock farmers operate (Cooper et al., 2008). ENSO and monsoons are also related to extreme climatic events such as droughts and floods in SSA and have historically had far-reaching implications. Strong ENSO-related droughts in the past, especially in 1982/83, 1991/92, and 1997/98, had strong effects in SSA states through widespread devastation of crops and livestock, e.g., in Zimbabwe, Swaziland, Lesotho, Botswana, and Zambia. Flooding has also been known to cause severe damage in countries like Mozambique and Malawi (Zinyengere, 2016). Although farming communities in SSA have learned over time to cope with climate variability through historical experiences, climate change may present novel climates that may go beyond recent historical experiences, thereby demanding that agricultural systems adjust differently.
Despite future greenhouse gas emissions, we are already locked into some warming in the future, such that to keep global temperatures increases at below 2°C as espoused in the 2015 Paris Agreement, there will be a need for urgent concerted global efforts. As it stands, warming in SSA is projected to continue and to be larger than the global annual mean warming, especially in the more arid regions, averaging around 2°C by the end of the 21st century (IPCC, 2014). Under business-as-usual high emissions scenarios, projections show an increase in average temperatures above the 2°C set by the Paris Agreement by the mid-21st century and up to 4°C by the end of the century (IPCC, 2014). Temperatures will rise highest in the southern and northern regions of Africa and relatively less in the central regions. Rainfall projections are more uncertain than temperature projections. Projections show, however, declining average rainfall in southern Africa and increasing rainfall in parts of central and eastern Africa by the mid-21st century (IPCC, 2013). As the climate changes significantly into the 21st century, the intensity and frequency of extreme climatic events in SSA will also grow in importance. Heavy rainfall events, extreme hot days, in-season dry spells, heat waves, and droughts are likely to increase, whereas the timing of the beginning of the rainy seasons will become more uncertain. Hot days are likely to increase significantly in the Sahel and parts of western and southern Africa and heavy rainfall events are likely to increase significantly in southern and eastern Africa (IPCC, 2014). These future climatic changes will have considerable impacts on agriculture in SSA, with the greatest impact expected to occur in the most marginal agricultural areas, where low and irregular rainfall is already experienced (Davis, 2011).
3. Impacts of Climate Change on Agriculture in Sub-Saharan Africa
Climate change will present considerable challenges to agriculture in SSA owing to the climate sensitivity of the predominantly dryland farming systems across the continent and the low adaptive capacity due to high prevalence of poverty. The aggregate impacts of climate change on crop production will probably be negative. Yields for maize in southern Africa are projected to decline on average by 18% and the aggregate yield for all crops combined by as high as 30% (Schlenkler and Lobell, 2010; Zinyengere et al., 2013). Yield changes of all crops combined in West Africa are also likely to be negative, with median yield losses projected at −11% by the end of the 21st century (Roudier ...