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# Agroforestry: An adaptation measure for sub-Saharan African food systems in response to increased weather extremes due to climate change

Abstract

This paper examines the impact of increasing weather extremes due to climate change on African food systems. The specific focus lies on agroforestry adaptation measures that can be applied by smallholder farmers to protect their livelihoods and to make their food production more resilient against the effects of those weather extremes. The adoption potentials for agroforestry is evaluated, taking into consideration regional environmental and socio-economic differences, and possible barriers for adoption with respect to extrinsic and intrinsic factors are outlined. According to the indicators that approximate extrinsic factors, a high adoption potential for agroforestry is likely to be found in Angola, Botswana, Cameroon, Cabo Verde, Gabon, Ghana, Mauritania and Senegal. A very low potential exists in Somalia, Eritrea, South Sudan and Rwanda.

# Introduction

Several decades of scientific work on a better understanding of the earth’s climate system have led to increasing certainty that changes in the climate system are influenced by human activity. As the 5th Assessment Report of the IPCC notes, there is 95% confidence that the increase in global surface temperature is caused by the anthropogenic increase in greenhouse gas concentrations (Stocker, 2013). As a result, more extreme weather occurrences have been predicted for many regions for the upcoming decades. Successfully coping with changes in weather patterns requires mitigation measures for future GHG emissions reductions along with adaptation measures, the latter adopted particularly in those regions that will be severely affected by future weather extremes.

In most of the developed Annex I countries, a well-functioning governance system provides financial resources and institutional stability for potentially large-scale investments in adaptation and mitigation measures within the national territories. In many developing countries, however, governance and institutions are poorly developed, resulting in a lack of financial investments to cope with climate change. Given these circumstances, affordable adaptation measures are required to be taken by citizens themselves on a local level to avoid adverse effects on their livelihoods.

An important field for investigating the effectiveness of adaptation measures against climate change are African smallholder, or subsistence farmers. In many parts of the African continent, smallholder farmers cultivate more than 70% of the arable and permanent cropland and are responsible for a very high proportion of local food and crop production (Morton, 2007). However, their lack of economic resources restricts them access to alternative livelihoods (Slingo et al., 2005). Given these circumstances, a worsening of climate variability, primarily decreases in precipitation and increases of droughts that have been predicted for large parts of Africa, highlight the importance for cost-effective adaptation measures for the agricultural sector in Africa. Without these measures, severe effects on food production are to be expected that greatly endanger the livelihood of local farmers and the people that to a great extent dependent on local food supply (Waha et al., 2013). If not adopted successfully, African food systems are unlikely to provide sufficient nutrition to a population that is growing by 4% annually, and that will thus further increase the stress on arable land (The World Bank, 2012).

This paper examines agroforestry as an adaptation measure that can be applied by smallholder farmers in order to increase the resilience of African food systems against increasing climate variability. In doing so this paper aims at responding to the following research question:

What is the adoption potential of agroforestry for smallholder farming in different countries of Sub-Saharan Africa to strengthen the resilience against increasing climate variability?

The paper proceeds as follows. Firstly, based on a literature review the predicted impacts following from climate change are synthesized for different African regions. Secondly, agroforestry is being introduced as a cost-effective adaptation measure. Lastly, adoption potentials for different regions are quantified and advice is given on increasing the adoption of agroforestry methods by addressing several identified barriers.

# Predicted impacts for Africa

Several studies have modeled and assessed the potential environmental and socio-economic impacts on the African content from climate change. Table \ref{table:literatureReview} provides a summary of the different studies. de Wit (2006) assess that predicted precipitation changes will significantly affect present surface water access across 25% of Africa’s land surface by the end of this century. They estimate that a 10% decrease in precipitation in regions with more than 1000 millimeters precipitation per year would reduce drainage by 17%, regions with less than 500 millimeters would experience reduced drainage by up to 50%. Hulme et al. (2001) estimate a temperature increase between 2 to 6 $$^{\circ}$$C by 2100. Temperature changes will have different impacts on different regions in Africa and are strongly related to changes in precipitation. As such, Burke et al. (2006) predict increased droughts over Northern Africa and a wetting over central Africa.

Most smallholder farmers in sub-Saharan Africa practice rain-fed agriculture and depend on local hydrological feedbacks (Lasco et al., 2014). Therefore increasing climate variabilities will have significant socio-economic impacts and several studies attempted to estimate these. A study done by Schlenker et al. (2010) showed that damages to yields of typical crops such as maize, sorghum, millet and groundnut are likely to exceed 7% by 2050 whilst yields from tropical crops such as rice could increase in regions with increasing flooding. This corresponds to other studies such as Jones et al. (2003) who predict a 10% decrease in maize production until 2050. Zinyengere et al. (2013) predict even more severe yield reductions, with a 18% decline for maize and an average crop decline of 30% for wheat, beans and sugarcane until 2100. Overall, crop responses to increasing climate variability tend to be negative for sub-Saharan Africa. Kurukulasuriya et al. (2006) did an economic estimate in which 10% temperature increase leads to a 13% decline in net revenue for smallholder famers. 10% increase in precipitation would in turn, according to their calculations, lead to a 40% net increase in revenue.

XX Study & Predicted impact
(de Wit 2006) & Decreased drainage 17% - 50%
(Schlenker 2010) & Increased crop damage 7% - 27%
(Jones 2003) & Decreased maize production by 10% until 2055
(Hulme 2001) & Temperature increase 2 - 6 $$^{\circ}$$C by 2100
(Kurukulasuriya 2006) & 10% temperature increase leads to 13% decline in net revenue. 10% increase in precipitation leads to 40% increase in net revenue
(Burke 2006) & Increased droughts over Northern Africa & wetting over central Afric